Dissertations / Theses on the topic 'In vitro gas production'

At the Forage Research Centre, Swedish University of Agricultural Sciences in Umeå a technique has been developed to describe the degradation of feeds in ruminant animals. The development of this technique has been made in collaboration with Dr J.W. Cone, Nutrition and Food, Animal Sciences Group of Wageningen UR, Lelystad, the Netherlands. Experiments have been performed in laboratories where feed samples have been incubated with rumen fluid and the amount of gas produced during the digestion has been measured continuously. These feed samples were analysed at three separate occasions. The purpose of this thesis was to identify and describe statistical procedures for detecting differences between feeds analysed within the same laboratory as well as differences between the same feeds analysed in two different laboratories (in Sweden and the Netherlands). To determine the rate of digestion and to describe to what extent feeds are digested in the rumen a gas production model was fitted, using non linear regression. In order to test whether there are significant differences between the feeds, three methods were applied. For each method, the variances were estimated differently. In the first method, Hotelling’s T2 tests and two sample t tests were performed. From these tests, differences between the feeds that were analysed within the same laboratory were detected whereas no differences between the same feeds analysed in two different laboratories could be found. In the other two methods, tests were performed using an assumption of normality. These two methods detected a larger number of differences between the feeds than the first method, primarily due to extremely underestimated variances. The first method is to be preferred since the estimated variances in this method are unbiased. This causes the result to be more reliable. For future experiments it is recommended that the feed samples are analysed at considerably more than three occasions. This would lead to better estimations in the first method and consequently the result would be enhanced.

The aim of this thesis was to investigate the suitability and application of an in vitro gas production technique as a routine analytical tool in animal nutrition studies. Firstly, the effect of several biological, chemical and physical factors on the measurement of gas production were investigated. These factors included incubation temperature, head-space pressure, shaking movement of the in vitro cultures, the nature of the feedstuff (chemical composition, particle size and drying process), the source of the microbial inoculum and the apparatus used to measure gas production. Secondly, two potential applications for the technique were investigated; (1) as a routine feed analysis tool for the prediction of the digestible energy (DE) content of equine feeds and (2) as a screening method for investigating the potential use of novel feed additives. The first application was investigated by incubating sixteen feedstuffs of known DE. Gas production parameters, DM loss and VFA production were then used to derive prediction equations. The best prediction equation was DE = -0.68 + 0.01087 DML + 6.82 Z - 2.297 log L_T (R² = 0.878; RSD = 0.99; where DML is dry matter loss in vitro, Z is a rate parameter and L_T is the lag time for gas production). The second application was investigated using four antibiotics; monensin, avoparcin, penicillin G and chloramphenicol in the automated gas production system. Differences in gas production profiles were detected between antibiotic supplemented and control fermentations suggesting that the technique can be used to screen feed additives. Results presented in this thesis inform the development of standardised methodologies and procedures for use during in vitro gas production studies, thus enabling this technique to be adopted as a robust, reliable and routine analytical tool in animal nutrition studies.

This study was aimed to assess the effect of fecal inocula from horses fed on concentrate (restricted amount daily) and oat straw (ad libitum) supplemented with fibrolytic enzymes on in vitro hindgut activity. Cellulase (CE), xylanase (XY) and CE+XY (1:1 v/v; CX) were tested at three levels (μL/g DM): 0, 1 and 3, in addition to control without enzyme addition (EP0). Fecal inocula were collected from 16 Quarter Horse mares supplemented with enzyme at 0 (FCOwithout enzyme), or fed 10 ml enzyme/mare/day of CE (FCE), XY (FXY) or CE+XY (1:1 v/v; FCX) for 15 days. The fecal content mixed with the culture media were used for incubation in bottles containing 1 g DM of substrate (a mixture of concentrate and oat straw (1:1 DM)). Gas (GP), methane (CH4) and carbon dioxide (CO2) productions were measured at 2, 4, 6, 8, 10, 12, 24 and 48 h post-incubation. Interactions occurred (P˂0.05) between fecal type × enzyme product for the asymptotic GP, the rate of GP, CH4 production, and fermentation kinetic parameters. Moreover, interactions were observed (P˂0.05) between fecal type × enzyme product × enzyme dose for the rate of GP, CH4 production and DM digestibility. Xylanase at 3 μL/g DM with FXY fecal increased (P˂0.05) the asymptotic GP and calculated fermentation parameters. At 24 h and 48 h and without enzyme, FCX and FXY, respectively, had the highest (P˂0.05) CH4 production. It can be concluded that xylanase enzyme at 3 μL/g DM was the most effective compared to other treatments.

The purpose of this thesis was to adapt the in vitro gas production technique (IVGPT) to estimate the rumen degradation profile of feed protein and to investigate the effect of sample preparation on the estimated kinetics of silage carbohydrate and protein degradation in the rumen.

The influence of microbial activity on the pattern of gas production and the possibility of developing a protocol for standardising the microbial activity of ruminal fluid were investigated (chapter 2). Firstly, ruminal fluid was diluted 1:2, 1:5, 1:9 and 1:20 (v/v) with buffer solution and the in vitro gas production from cellulose, glucose, hay and ryegrass studied. Gas production at 4, 24 and 120h were significantly decreased as the ratio of buffer solution to ruminal fluid increased. For each substrate, incubation with ruminal fluid diluted 1:2 (v/v) gave a higher (P<0.5) asymptotic value 'B', rate 'C' of gas production and lower lag time than when incubated in the 1:5, 1:9 and 1:20 dilutions. Secondly, the effect of frequency of ovine ruminal sampling on microbial activity and substrate fermentation was investigated. The bacterial DM, bacterial absorbance and blank's gas volume were significantly affected by daily sampling of ruminal fluid. Daily sampling of rumen fluid did not significantly affect the gas production degradability parameters (B,C and Lag) until the bacterial DM fell below 0.09 g DM/10 cm³ strained rumen fluid. Bacterial DM was strongly related to the absorbance of ruminal fluid (R² = 0.99, p<0.001), suggesting that standardisation of the level of microbial activity between days and laboratory can be achieved by estimating the bacterial DM from the absorbance of the strained ruminal fluid. The influence of donor diet on initial microbial concentration and gas production degradability was studied (chapter 3). Bacterial DM, bacterial absorbance and the blanks' gas volume increased significantly as the ratio of sheep pellet to hay increased. The gas production degradability parameters (B, C and Lag) were also affected by changing the donor diet ratio of sheep pellets and hay. NDF digestibility of cellulose and hay was not significantly affected by donor diet. Bacterial DM was strongly related to the absorbance of ruminal fluid and the blanks' gas volume (R² = 0.99, p<0.001). These results suggest that changing the ratio of concentrate to hay reduced the initial bacterial concentration and affected the gas production degradability parameters.

ABSTRACT: The study aimed to assess the nutritive value in vitro of 4 feeds (grains and forages) commonly used in horses nutrition in Mexico, in the absence or presence of Saccharomyces cerevisiae at 4 mg/g DM. Fecal inoculum was obtained from 4 adult English Thoroughbred horses fed on restricted amount of concentrate and oat hay ad libitum. The incubated substrates included were corn gluten meal, soybean meal, oat grain and alfalfa hay. Gas production was recorded at 2, 4, 6, 8, 10, 12, 14, 24, 48 and 70 h using the Pressure Transducer Technique. Some ingredient × yeast interactions were observed (P < .020) for the asymptotic gas production (GP) and GP at 48 and 70 h of incubation. Yeast addition increased (P < .001) the asymptotic GP of concentrates compared to forages. Concentrate feeds had higher (P < .05) GP and lower (P < .001) rate of GP compared to forages without yeast. From 24 to 70 h of incubation, forages with or without yeast had lower (P < .05) GP compared to concentrates with yeast addition. Forages had higher fermentation pH compared to concentrates, but lower (P < .05) metabolizable energy (ME), in vitro organic matter digestibility (IVOMD) and microbial protein production (MBP) compared to concentrates. Yeast addition increased (P < .05) the asymptotic GP of oat grain and soybean meal, without affecting the rate of GP or lag time of both. Yeast treatment improved fermentation of feeds with higher effects on concentrates compared to forage. It was concluded that concentrate feeds had higher nutritive value than forages commonly fed to horses

Purple threeawn (Aristida purpurea Nutt.) is a native bunch grass that is avoided by grazers. It is capable of dominating old cropland and overgrazed pastures, limiting livestock carrying capacity, and degrading wildlife habitat. Traditional management tools have had little impact on threeawn dominance in semiarid regions of the west. Our objectives were to: 1) assess fire and nitrogen treatment effects on threeawn forage quality at various phenological stages to test their potential as pretreatments in a grazing strategy and 2) examine a threeawn-dominated plant community?s response to prescribed fire, nitrogen addition, and clipping. Fire improved threeawn forage quality with greater improvements in early phenological stages. Nitrogen had little effect on forage quality. Fire and nitrogen reduced threeawn while increasing cool season grasses. Light and moderate clipping following fire did not improve the efficacy of fire. Fire appears to an effective preliminary treatment to improve the chance of herbivory.

Due to the warming of the climate system, public opinion has increased its interest in greenhouse gas, with particular predilection for methane (CH4 ) and their relationship with livestock sector. For this reason, several researches have proposed different nutritional strategies to reduce methane production in ruminants. The two main aims of this thesis were: i) to study methodological factors affecting in vitro CH4 production and to develop a new approach to measure in vitro CH4 production; ii) to evaluate effectiveness of some nutritional strategies on in vitro CH4 reduction. The objectives have been achieved through the research activities and reported in five experimental contributions. The first contribution aimed to analyse specific factors affecting in vitro gas production (GP), CH4 production and their ratio by a meta-analysis approach using 274 control treatments from 39 scientific papers published over 12 years. The common factors included in the analysis were: the pressure in the GP equipment (constant or increasing), the incubation time (24 or ≥48 h), the timing of rumen fluid collection (before or after feeding of donor animals), the presence of N in the buffer solution (presence or absence), and the ratio between amount of buffered rumen fluid and feed sample (<130 or 130-140 or >140 ml/g DM). The NDF content of feed sample incubated (392 ± 175.3 g/kg) was considered as a continuous variable. Results showed that GP measures were influenced mainly by the incubation time; values of CH4 production were affected mainly by the ratio between amount of buffered rumen fluid and feed sample; values of CH4 proportion (CH4 /GP) were mainly affected by timing of rumen fluid collection. Results suggest that factors considered in the meta-analysis explained a significant part (about 65%) of variability of GP and CH4 measures obtained in vitro. Thus, a higher standardization of specific methodological protocols would be desirable in order to compare results of different trials. The second contribution compared two in vitro techniques (closed or vented bottles) of sampling and measuring CH4 production from ruminant feeds. Five feeds (meadow hay, ryegrass hay, corn grain, dry sugar beet pulp, and expeller flaxseed) were tested. The experimental design was: 2 incubations×5 feeds×3 replications×2 gas sampling techniques, plus 4 blanks (bottles without feed sample), for a total of 64 bottles incubated. Half of the bottles were not vented during the incubation, whereas the remaining were vented at a fixed pressure and gas was collected into a tight bag connected to each bottle. At the end of each incubation, gas samples were sampled from the headspace of closed bottles or from headspace and bags of vented bottles and analyzed for CH4 concentration. GP values were adjusted or not for the amount of CO2 solubilized in the fermentation fluid. Values of CH4 concentration (ml CH4 /100 ml gas) and production (ml CH4 /g DM) were computed using corrected or uncorrected GP values. Closed bottles showed lower uncorrected GP (−18%) compared with vented bottles, whereas the correction for dissolved gas reduced but did not remove differences between techniques. Closed bottles showed unadjusted CH4 concentrations 23% greater than that of vented bottles, but the adjustment of measurements for solubilized CO2 reduced but did not remove this difference. Adjusted CH4 production was not influenced by technique. Closed bottles provide good measurements of CH4 production but not of GP. Venting of bottles at low pressure permits a reliable evaluation of total GP and CH4 production. The third contribution evaluated the influence that changes in main dietary constituents (starch:ADF ratio, protein and lipid contents) could have on in vitro GP, CH4 concentration and production. All changes have been made within ranges of diets used in intensive farms of the North Italy. A reference diet was used (273, 361, 158, and 33 g/kg DM of starch, aNDF, CP, and lipids, respectively). Other 6 diets had a smaller or a greater starch:ADF ratio (0.40 or 1.77, respectively), CP content (115 or 194 g/kg DM, respectively), or lipid content (26 or 61 g/kg DM, respectively), compared to the reference diet. The experimental design was: 4 incubations × 7 diets × 5 replications, plus 20 blanks (5 blanks/run), for a total of 160 bottles. Bottles were vented at fixed pressure and at the end of each incubation, gas samples were collected from the bottle headspace and analyzed for CH4 . The proportion of CH4 lost with venting was estimated. An increasing starch:ADF ratio reduced GP per g DM and per g TDMd, increased the amount of CH4 produced per g DM, whereas CH4 produced per g TDMd was unchanged. The increase of CP content decreased GP, whereas CH4 production was reduced in low protein diet only when expressed as proportion of GP. The increase of lipid content reduced GP per g DM, but no influences were observed on CH4 values. Results of this study showed that the magnitude of effects exerted by the dietary changes on in vitro fermentation was small. The fourth contribution aimed to explore effects of 4 pure plant extracts (allyl-sulfyde; cinnamaldehyde; eugenol; limonene) and 1 synthetic compound (monensin), all with antimicrobial properties, added to a commercial diet for dairy cows, on GP, CH4 concentration and production. Two dosages were tested: 3 or 30 mg/g of diet for pure plant extracts, 0.015 or 0.030 mg/g of diet for monensin. Incubation procedures were the same as the previous experiment. The experimental design was: 4 incubations×5 additives×2 dosages×3 replications, plus 12 bottles as control (without additive; 3/run) and 12 bottles as blanks (3/run), for a total of 144 bottles. Results showed that low dosages of all compounds did not exert any effect on in vitro GP and CH4 production. Compared to the control, high dosage of allyl-sulfyde, cinnamaldehyde, eugenol, limonene, and monensin significantly reduced in vitro GP (ml/g DM; -16%, -12%, -9%, -38%, -12%, respectively). In vitro CH 4 production was significantly reduced only by high dosage of allyl-sulfyde, cinnamaldehyde, limonene, and monensin (-32%, -12%, -43%, -18%, respectively, compared to the control). Only high dosage of allyl-sulfyde and limonene significantly reduce CH4 proportion (-18%, -12% respectively, compared to the control). The most promising results were observed for cinnamaldehyde, as the depression of CH4 production was not accompanied by a reduction of in vitro degradability. The fifth contribution investigated the possibility to reduce in vitro gas and CH4 production by combining a direct inhibitor of methanogenisis (chloroform) with two indirect inhibitors: i) nitrate, acting as a H2 sink, and ii) saponins, acting as antiprotozoal agent. The experiment was conducted using a semi-continuous flow system (RUSITEC ®). A diet, based on grass hay, was incubated alone (diet 1) or supplemented with 31.5 g/kg of nitrate (diet 2) or with 50 g/kg of saponins extracted from ivy extract (diet 3). Three diets were incubated without or with chloroform (2 µL/L), obtaining a total of 6 dietary treatments. Each of the 6 dietary treatments was incubated in four vessels, for a total of 24 vessels. Each vessel was inoculated with 800 ml of buffered rumen fluid. Whole incubation lasted 21 d. Total GP (on average 2.56 L/d) was not affected by diet or chloroform addition. When incubated alone, chloroform, nitrate and saponins reduced daily CH4 production by 96, 66 and 22%, respectively. However, when chloroform was combined with indirect inhibitors, neither nitrate or saponins had any additional effect in chloroform treated vessels on in vitro CH4 production. Results suggest that no synergistic effects emerged between the direct inhibitor and the two indirect inhibitors.
Il recente scenario del riscaldamento climatico globale, ha portato ad un maggiore interesse dell’opinione pubblica riguardo ai gas che causano l’effetto serra, ponendo particolare attenzione al gas metano (CH4 ) e alla sua relazione con il settore zootecnico. Per questa ragione, numerosi gruppi di ricerca hanno proposto delle strategie nutrizionali per ridurre le emissioni di CH4 da parte dei ruminanti. Nella presente tesi sono stati sviluppati due obiettivi principali. Il primo riguardava lo studio dei fattori metodologici che influenzano la produzione in vitro del CH4 e lo sviluppo di un nuovo approccio per la misurazione dello stesso gas prodotto durante delle fermentazioni in vitro. In secondo luogo, si è inteso valutare l’efficacia di alcune strategie nutrizionali sulla riduzione della produzione di CH4 . Tali obiettivi sono stati raggiunti attraverso cinque diverse attività di ricerca. Nel primo lavoro è stato valutato l’effetto che specifici fattori metodologici possono avere sulla produzione in vitro di gas e di CH4 (espresso sia in termini di produzione che di proporzione). Questa analisi è stata effettuata attraverso un approccio di meta-analisi utilizzando 274 osservazioni, che rappresentavano i trattamenti di controllo di 39 articoli scientifici pubblicati negli ultimi 12 anni. I fattori considerati erano: la pressione che si forma nello spazio di testa dello strumento utilizzato per le fermentazioni in vitro (costante o incrementale), il tempo di incubazione (24 o ≥48 ore), il momento di raccolta del liquido ruminale (prima o dopo la somministrazione del pasto agli animali donatori), la presenza di azoto nella composizione della saliva artificiale (presenza o assenza), e il rapporto tra la miscela di liquido ruminale e saliva artificiale sul campione alimentare incubato (130 or 130-140 or >140 ml/g DM). Questi cinque fattori sono stati considerati come variabili discrete, invece il contenuto di NDF del campione alimentare incubato (392 ± 175.3 g/kg) è stato considerato come variabile continua. I risultati hanno mostrato che la produzione totale di gas è principalmente influenzata dal tempo di incubazione, mentre la produzione di CH4 è influenzata soprattutto dal rapporto tra la miscela di liquido ruminale e saliva artificiale sul campione alimentare incubato. Quando invece il CH4 viene espresso in termini di proporzione sul gas totale prodotto, i valori sono principalmente influenzati dal momento di raccolta del liquido ruminale. Inoltre, questa meta-analisi dimostra che i fattori considerati spiegavano una parte considerevole (circa il 65 %) della variabilità dei dati di gas e CH4 prodotti durante le fermentazioni in vitro. Quindi, sarebbe desiderabile una maggiore standardizzazione dei protocolli metodologici internazionali, in modo da facilitare il confronto di dati ottenuti in diversi sperimentazioni. Il secondo contributo sperimentale ha inteso mettere a punto una procedura di raccolta e di misurazione del CH4 prodotto, utilizzando due diverse tipologie di fermentazione in vitro: i) un “sistema aperto”, con sfiato regolare del gas all’interno di un sacchetto connesso alle bottiglie di fermentazione, dal quale viene prelevato il campione di gas per l’analisi del CH4 ; ii) un “sistema chiuso”, con accumulo progressivo dei gas di fermentazione nello spazio di testa delle bottiglie, dal quale viene prelevato il campione per l’analisi del CH4 . Per le fermentazioni sono stati usati cinque alimenti singoli utilizzati nell’alimentazione dei ruminanti (fieno polifita, loietto, farina di mais, panello di lino e polpe di bietola). Il disegno sperimentale prevedeva: 2 incubazioni × 5 alimenti × 3 replicazioni per alimento × 2 tecniche di campionamento del gas, più 4 bianchi (bottiglie incubate senza campione alimentare), per un totale di 64 bottiglie incubate. Metà delle bottiglie non venivano sfiatate, mentre le rimanenti venivano sfiatate a pressione fissa e il gas era raccolto in un sacchetto a tenuta connesso ad ogni bottiglia. Alla fine di ogni incubazione, il gas veniva campionato dallo spazio di testa delle bottiglie utilizzate per il sistema chiuso o dallo spazio di testa e dal sacchetto delle bottiglie utilizzate per il sistema aperto. Tutti i campioni sono stati poi analizzati per quantificare la concentrazione di CH4 . I valori di gas prodotto venivano o meno corretti per la quantità di CO2 che si era disciolta nel liquido di fermentazione. I valori di produzione (ml CH4 /g DM) e di proporzione (ml CH4 /100 ml gas) di CH4 sono stati calcolati utilizzando i valori corretti o non corretti di produzione di gas totale. Il sistema chiuso ha mostrato una produzione di gas totale non corretto inferiore (-18%) rispetto al sistema aperto, mentre la correzione del gas ha ridotto ma non rimosso le differenze tra le due tecniche. Le bottiglie chiuse hanno mostrato una proporzione di CH4 non corretto superiore (+23%) rispetto al sistema aperto, mentre la correzione ha ridotto ma non rimosso le differenze tra le due tecniche. La produzione di CH4 corretto non è stata influenzata dalla tecnica utilizzata. Concludendo, il sistema chiuso non offre buone misurazioni della produzione del gas, mentre il sistema aperto consente una valutazione attendibile sia del gas che del CH4 prodotto. Nel terzo contributo sperimentale è stato valutato l’effetto che le variazioni quantitative dei principali componenti chimici (rapporto amido:ADF, contenuto proteico e contenuto lipidico) di diete per vacche da latte, posso avere sulla produzione di gas e CH4 . Le variazioni sono state fatte tenendo conto degli intervalli di fibra, amido, proteina e lipidi effettivamente utilizzate negli allevamenti intensivi del Nord Italia. La dieta di riferimento utilizzata aveva la seguente composizione chimica: 273, 361, 158, e 33 g/kg SS di amido, NDF, CP, e lipidi, rispettivamente. Le altre 6 diete avevano un minore o maggiore rapporto di amido:ADF (0.40 or 1.77, rispettivamente), o di contenuto proteico (115 or 194 g/kg DM, rispettivamente), o di contenuto lipidico (26 or 61 g/kg DM, rispettivamente), rispetto alla dieta di riferimento. Il disegno sperimentale prevedeva: 4 incubazioni × 7 diete × 5 replicazioni per dieta, più 20 bianchi (bottiglie incubate senza campione alimentare), per un totale di 160 bottiglie incubate. Il gas prodotto veniva regolarmente sfiatato a pressione fissa e alla fine di ogni incubazione un campione di gas veniva raccolto dallo spazio di testa delle bottiglie e veniva analizzato per misurare la concentrazione di CH4 . La quantità di CH4 perso durante lo sfiato del gas di fermentazione è stata stimata. I risultati mostrano che all’aumentare del rapporto amido:ADF si riduce la produzione di gas (per g di SS e per g di degradabilità "vera" della SS), aumenta la produzione di CH4 (per g di SS), mentre la produzione di CH4 espressa come g di degradabilità "vera" della SS non varia. All’aumentare del contenuto proteico si riduce la produzione di gas, mentre la proporzione di CH4 è stata ridotta solo nella dieta ipoproteica. L’aumento del contenuto lipidico ha ridotto la produzione di gas (per g di SS), ma non ha influenzato i valori di CH4 . Si può quindi concludere che l'entità degli effetti, esercitati dalle variazioni quantitative dei principali componenti chimici delle diete sulla fermentazione in vitro, è stata quasi inesistente. Il quarto lavoro ha inteso valutare l’effetto di quattro estratti puri di piante (allil-sulfide, cinnamaldeide, eugenolo e limonene) e di un composto sintetico (monensin), tutti con proprietà antimicrobiche, utilizzati come additivi di una dieta per vacche da latte, sulla produzione di gas e CH4 . Sono stati utilizzati due diversi dosaggi: 3 or 30 mg/g di per gli estratti puri di piante, 0.015 or 0.030 mg/g di dieta per il monensin. Le procedure di incubazioni utilizzate erano le stesse dell’esperimento precedente. Il disegno sperimentale prevedeva: 4 incubazioni × 5 additivi × 2 dosaggi × 3 replicazioni, più 12 bianchi (bottiglie incubate senza campione alimentare, 3 per incubazione), e 12 controlli (dieta incubata senza additivi, 3 per incubazione) per un totale di 144 bottiglie incubate. I risultati hanno mostrato che tutti i composti testati con il basso dosaggio non hanno mai influenzato la produzione in vitro di gas e CH4 . Rispetto al controllo, gli alti dosaggi di allil- sulfide, cinnamaldeide, eugenolo, limonene, e monensin hanno ridotto significativamente la produzione in vitro di gas (ml/g DM; -16%, -12%, -9%, -38%, -12%, rispettivamente). La produzione in vitro di CH4 è stata significativamente ridotta solo dell’alto dosaggio di allil-sulfide, cinnamaldeide, limonene, e monensin (-32%, -12%, -43%, -18%, rispetto al controllo). Solo gli alti dosaggi di allil- sulfide e limonene hanno ridotto significativamente anche la proporzione di CH4 (-18% e -12% rispetto al controllo). I risultati più promettenti sono stati osservati per la cinnamaldeide, che ha depresso la produzione CH4 senza influenzare negativamente gli altri parametri fermentativi. Il quinto e ultimo contributo sperimentale ha valutato la possibilità di ridurre la produzione in vitro di gas e CH4 attraverso la combinazione di un diretto inibitore del CH4 (cloroformio) con due inibitori indiretti: i) i nitrati, che agiscono come accettori di idrogeno e ii) le saponine, dei noti agenti antiprotozoari. L’esperimento è stato condotto utilizzando un sistema di simulazione ruminale a flusso semi-continuo (RUSITEC®). Una dieta base è stata incubata singolarmente (dieta 1) o addizionata con 31.5 g/ kg di nitrati (dieta 2) o con 50 g/kg saponine ottenute dall’estratto d’edera (dieta 3). Queste tre diete sono state incubate senza o con l’aggiunta di cloroformio (2 µL/L), ottenendo un totale di 6 trattamenti testati. Ogni trattamento è stato incubato in quattro bottiglioni, per un totale di 24 bottiglioni. L’intera incubazione è durata 21 giorni. I risultati mostrano che la produzione totale di gas (in media 2.56 l/d) non è stata influenzata dalla dieta o dalla presenza del cloroformio. Quando utilizzati singolarmente, cloroformio, nitrati e saponine riducono la produzione giornaliera di CH4 del 96, 66 e 22%, rispettivamente. Nonostante ciò, quando il cloroformio era combinato con inibitori indiretti, non si è evidenziato nessun effetto addizionale sulla riduzione di CH4 prodotto. Concludendo, si può quindi affermare che nessun effetto sinergico è emerso tra l’inibitore diretto di CH4 e i due inibitori indiretti.

Com o objetivo de estudar o uso de inóculo de fezes em substituição do conteúdo ruminal de bubalinos na técnica in vitro de produção de gases, este presente trabalho comparou as avaliações realizadas em três ensaios. Foram utilizados três bubalinos da raça Mediterrâneo, machos, adultos, castrados, fistulados no rúmen com média de peso vivo de 450 (± 18,7) kg. Estes animais receberam uma dieta basal, composta de silagem de milho (70%) e concentrado (30%). Estes animais foram os doadores dos 2 tipos de inóculos, que foram conteúdo ruminal (CR) e fezes. O primeiro ensaio realizado foi com alimentos concentrados: grão de milho, farelo de soja, farelo de trigo e farelo de algodão; o segundo ensaio foi com leguminosas forrageiras: alfafa (Medicago sativa L. ), estilosantes pioneiro (Stylosanthes macrocephala cv. Pioneiro), soja perene (Neonotonia wightii) e leucena (Leucaena leucocephala); e o terceiro e último ensaio foi realizado com gramíneas forrageiras: capim braquiarão (Brachiaria brizantha cv. Marandu), capim buffel (Cenchrus ciliaris L. cv. Biloela), estrela africana (Cynodon plectostachyus) e capim mombaça (Panicum maximum Jacq. cv. Mombaça). Os valores médios obtidos de produção potencial de gases em cada ensaio foram menores (P<0,05) para as amostras fermentadas com inóculos de fezes que com conteúdo ruminal, sendo respectivamente, para concentrados (140,23 e 194,08 mL.g-1MS), gramíneas (161,99 e 230,25 mL.g-1MS) e leguminosas (141,78 e 170,70 mL.gm-1MS). Conclui-se que inóculos de fezes não apresentam condições satisfatórias para substituição do inóculum com conteúdo ruminal para uso na técnica de produção in vitro de gases.
In order to study the use of faeces as inoculum as alternative for buffalo rumen contents in the in vitro gas production technique, the present work evaluations of three tests. We used three Mediterranean buffalos, male, adult, neutered, fistulated in the rumen, with an average live weight of 450 (± 18.7) kg. These animals received a basal diet composed of corn silage (70%) and concentrated (30%). These buffalo were the donors of the two types of inocula, rumen content (CR) and faeces. The first test was carried out with concentrate foods: corn grain, soybean meal, wheat bran and cottonseed meal, the second test was with legumes: alfalfa (Medicago sativa L. ), Pioneiro estilo (Stylosanthes macrocephala cv. Pioneiro) , perennial soybean (Neonotonia wightii) and leucaena (Leucaena leucocephala) and the third and last test was carried out with grasses: Marandu grass (Brachiaria brizantha cv. Marandu), buffel grass (Cenchrus ciliaris L. cv. Biloela), African Star grass (Cynodon plectostachyus) and Mombasa grass (Panicum maximum Jacq. cv. Mombasa). The average values of potential production of gas in each test were lower (P<0.05) for samples fermented with an inoculum of faeces with rumen contents, being respectively, for concentrates (140.23 and 194.08 mL.g-1MS), grasses (161.99 and 230.25 mL.g-1MS) and legumes (141.78 and 170.70 mL.g-1MS). It follows that fecal inoculum unsatisfactory condition for replacing the inoculum with rumen technique for use in the in vitro production of gases technique.

Os animais contribuem para o aumento da concentração de metano na atmosfera através da fermentação de tanques de esterco e da fermentação do trato digestivo (fermentação entérica). A fermentação entérica dos ruminantes, pseudo-ruminantes (cavalos, asno, mulas) e não ruminantes produzem em média 80 Tg/ano de metano e representam 28 % do metano antropogênico global emitido, dos quais 95 % provêm dos ruminantes. Os objetivos destes trabalhos foram (i) rastrear novos materiais com potencial forrageiro que contenham tanino e que promovam redução de metano entérico; (ii) estudar a influência dessas plantas sobre a produção de metano e parâmetros fermentativos in vitro; e (iii) estudar a influência dessas plantas sobre a população de Fibrobacter succinogenes e a comunidade metanogênica no meio de fermentação. Os resultados são apresentados na forma de capítulos, sendo o primeiro objetivo descrito no Capítulo 3, no qual é descrita a caracterização das leguminosas taniníferas Styzolobium aterrimum (STA), Styzolobium deeringianum (STD), Leucaena leucocephala(LEU), Mimosa caesalpiniaefolia Benth (MIC). Estas plantas foram avaliadas pela composição química e quantificação de compostos fenólicos e bioensaio até 96 h de incubação in vitro; tendo Cynodon x cynodon (CYN) como controle para avaliar a produção de gás potencial (A), a fase lag (L), a taxa fraccional de fermentação (\'mü\') e o incremento de gás devido à adição de PEG após 8, 24 e 48 h de incubação nas cinco plantas. As leguminosas tiveram melhor desempenho fermentativo que a gramínea, com exceção de MIC. Entretanto, a fermentação de todas leguminosas foi limitada diferentemente pela presença de tanino, da fibra indigestível ou pela ação aditiva de ambos. Entre todas as plantas, LEU mostrou ser uma forragem de boa qualidade para suplementação protéica em dietas de ovinos, assim como STA e STD, contanto que para estas haja um melhor manejo de produção para evitar o alto conteúdo de fibras, especialmente de FDA. MIC poderia ser incluído na dieta de ovinos em baixa concentração, não com a finalidade principal de suplementação protéica, mas explorando esta leguminosa como aditivo para mitigação de metano. No Capítulo 4 são apresentados os resultados de outro ensaio in vitro (segundo objetivo). A técnica in vitro de produção de gás foi utilizada para avaliar as quatro leguminosas taniníferas (STA, STD, LEU e MIC) e o CYN como controle em dois horários, no t1/2 (tempo para obtenção da metade da GP) e após 24 h de incubação, medindo a produção total de gás, metano, amônia, ácidos graxos de cadeia curta (AGCC), massa microbiana (MM) e a degradabilidade verdadeira da matéria seca (VDMS). A produção de metano em t1/2 foi reduzida (P < 0,05) com adição das leguminosas em 17% e quando relacionado à VDMS, esta redução alcançou em média 50% com LEU e STA e 37% com MIC e STD. LEU e STA causaram aumento significante na MM seguida por STD, MIC e CYN. A relação MM/SCFA em t1/2 foram maiores para LEU (14,7) e STA (14,1) seguida por STD (6,1), MIC (5,6) e CYN (4,6). A maior MM para LEU e STA sugere uma produção de ATP maior, porém, as diferentes proporções de AGCC demonstraram diferentes rotas de aquisição de ATP. O Capítulo 5 se refere à quantificação de linhagens de bactéria ruminal, a qual foi realizada utilizando primers específicos para detecção de seqüências de gene 16S rDNA para metanogênicas e para a bactéria celulolítica Fibrobacter succinogenes através da reação em cadeia da polimerase em tempo real (qPCR). Foi também investigado a influência das leguminosas na comunidade metanogênica através da eletroforese em gel com gradiente denaturante (DGGE) de seqüências de gene 16S rDNA. As metanogênicas em t1/2 foram 2,0 e 0,9 vezes menores que com STA e LEU comparadas com o controle, mas foram 2,5 e 0,5 vezes maiores com MIC e STD. A população de F.succinogenes foi 2,3 e 1,8 vezes menores do que o controle quando LEU e STA foram incubadas. A análise de DGGE para metanogênicas resultou em diferente distribuição de bandas com os tratamentos. CYN apresentou algumas bandas mais fortes, as quais se tornaram fracas com as leguminosas, exceto em STA. Algumas bandas tanto desapareceram, como em LEU, STA e MIC, ou se tornaram mais fracas, especialmente em STA. MIC apresentou ligeiro aumento no número de bandas fracas. É confirmado que as plantas taniníferas estudadas foram capazes de reduzir a emissão de metano com diferentes proporções dos produtos finais de fermentação, afetando negativamente a população de F. succinogenes e causando alterações na estrutura da comunidade metanogênicas
Animals contribute to increasing the methane concentration in the atmosphere through the fermentation of livestock manure and the fermentation in the digestive tract, e.g, enteric fermentation. The enteric fermentation of ruminants, pseudoruminants (horses, donkeys, mules) and non-ruminants produce an average of 80 Tg/year of methane and comprise 28 % of global anthropogenic methane emission, from which 95% arise from ruminants. The aims of this study were (i) to scan new potential forage containing tannin, which may reduce enteric methane emission; (ii) to study the influence of those plants on methane production and fermentative parameters in vitro; (iii) to study the influence of those plants on the population of Fibrobacter succinogenes and the methanogen community in the fermentation fluid. The results are presented in the form of chapters, being the first objective studied described in the Chapter 3, in which refers to the characterization of the tannin-rich legumes Styzolobium aterrimum (STA), Styzolobium deeringianum (STD), Leucaena leucocephala(LEU), Mimosa caesalpiniaefolia Benth (MIC). They were appraised for the chemical composition, quantification of phenolic compounds and bioassay up to 96 h in vitro incubation using Cynondon x cynodon (CYN) as control, to evaluate the potential gas production, (A), lag phase (L), fractional rate of gas production (\'mü\') and the gas increment due to PEG addition after 8, 24 and 48 h incubation of the five plants. Legumes showed better fermentative performance (except MIC) than the grass. However, each legumes fermentation was limited diferently by the presence of condensed tannin or the indigestible fiber or by the additive action of both. Among the plants, LEU showed good quality forage for protein supplementation in sheep diets as well as STA and STD as long there is an agriculture management to reduce indigestible fiber, specially ADF. MIC could be included in a sheep diet in low concentration, aiming not the protein supplementation, but exploiting it as an additive to methane mitigation. In Chapter 4 the second object is discussed describing an in vitro gas test to evaluate the four tannin-rich legumes (STA, STD, LEU and MIC), and CYN as control at two main time points: t1/2 (time of half maximal gas production) and 24 h, measuring total gas production , methane, ammonia, short chain fatty acids (SCFA), microbial mass growth (MM) and true substrate degradability (TSD). Methane production at t1/2 was reduced (P < 0.05) with addition of legumes by 17 % but when related to TSD this reduction reached on average 50 % with LEU and STA and 37% with MIC and STD. LEU and STA caused a significant increase in MM followed by STD, MIC, and CYN. Additionally, high MM/SCFA ratios in t1/2 were found in LEU (14.7) and STA (14.1) and followed by STD (6.1), MIC (5.6) and CYN (4.6). The higher MM in LEU and STA suggested higher ATP production; however, the different proportion of the SCFA demonstrated different routes of ATP acquisition. Chapter 5 refers to the quantification of specific strains of rumen bacteria, which was performed using designed primers for detecting 16S rDNA gene sequences for methanogens and the cellulolytic bacteria Fibrobacter succinogenes by real-time polymerase chain reaction (qPCR). Also, the influence of those four legumes on the methanogenic community was investigated using denaturing gradient gel electrophoresis (DGGE) of 16S rDNA gene. Methanogens at t1/2 were 2.0 fold and 0.9 fold lower with STA and LEU compared to the control, but they were 2.5 fold and 0.5 fold higher with MIC and STD. F. succinogenes population was 2.3 and 1.8 fold lower than the control when LEU and STA was applied. DGGE analysis of the methanogenic population resulted in different band patterns with treatments. CYN presented some strong bands, which became weaker with the legumes, except in STA. Some bands either disappeared, as in LEU, STA and MIC, or became weaker, especially in STA. MIC increased slightly the number of weak bands. It is confirmed that the studied taninniferous plants were able to reduce enteric methane with different fermentation products proportions, as well negatively affected F. succinogenes population and caused changes in the methanogenic community structure

Na alimentação animal, o sorgo pode ser explorado de diversas formas. Além dos grãos, a planta pode ser oferecida na forma de silagem, rolão, verde ou ainda pastejada; embora o valor nutritivo pode sofrer algumas variações pela presença ou ausência de compostos fenólicos como os taninos condensados. O objetivo deste trabalho foi avaliar a composição química-bromatológica, qualidade fermentativa e produção de gases in vitro nas silagens de sorgo granífero adicionados com diferentes níveis de guandu. O estudo foi dividido em dois experimentos. O primeiro estudo (Capítulo 3) avaliou os efeitos da adição de forragem de guandu sobre a composição química-bromatológica e fermentativas da silagem de sorgo granífero. Os tratamentos foram compostos por: T1 - Silagem com 100% de sorgo, T2 - Silagem com 25% de guandu e 75% de sorgo, T3 - Silagem com 50% de guandu e 50% de sorgo, T4 - Silagem com 75% de guandu e 25% de sorgo e T5 Silagem com 100% de guandu. As variáveis estudadas para a composição química e fermentativas das silagens foram: matéria seca (MS), proteína bruta (PB), fibra em detergente neutro (FDN), fibra em detergente neutro (FDA), carboidratos totais (CHOT), matéria mineral (MM), fenóis totais (FT), taninos totais (TT), taninos condensados (TC), pH, capacidade tampão (CT), perdas fermentativas e ácido lático. A adição de guandu promoveu efeito linear (P<0,01) nas silagens para os teores de MS, PB, FDN, FDA, FT, assim como para as perdas fermentativas de MS da silagem. Enquanto para os teores de CHOT, MM e TC verificaram-se respostas quadráticas (p<0,01) entre as silagens. Inclusões de 25, 50 e 75% de guandu, com base na matéria fresca, seriam suficientes para melhorar o valor nutricional assim como para se obter melhor padrão fermentativo da silagem de sorgo. O segundo estudo (Capítulo 4) avaliou a produção total de gases, metano, degradabilidade da MS (DMS) e degradabilidade da MO (DMO) em silagens de sorgo granífero com níveis crescentes de guandu através da técnica in vitro de produção de gases. Foram avaliadas as cinco silagens de sorgo granífero com níveis crescentes (0, 25, 50, 75 e 100%) de guandu utilizados como substratos. Para avaliar o efeito do tanino nas silagens sobre a produção de gases, procedeu-se um bioensaio, no qual os substratos foram incubados na presença de polietileno glicol (PEG), macro molécula capaz de ligar-se aos taninos presente no substrato, liberando os nutrientes para a fermentação; sendo o efeito do tanino medido pelo incremento na produção de gases. Não houve diferença estatística para a produção total de gases e metano para os níveis de inclusão do guandu, entretanto houve diferença significativa para o contraste nível zero e a inclusão do guandu. Para os incrementos também não houve diferença significativa para as variáveis (PG, CH4, DMS e DMO). Por outro lado, houve maior PG e maior incremento para o nível de 25% de guandu com a presença do PEG. Foi encontrado maior emissão de metano e incremento de metano para o nível 50% de guandu, quando comparado com os demais níveis. Houve maior DMS e DMO no substrato com 100% de guandu com a presença do PEG. Concluiu-se que a adição de forragem de guandu na silagem de sorgo aumentou o conteúdo de PB e reduziu os teores de FDN, implicando um melhor valor nutritivo das silagens, contudo os taninos condensados precisariam ser monitorados para futuros experimentos in vivo
In animal nutrition, sorghum can be used in various ways. Besides grain, the plant can be offered as silage, pollard, green or even grazed. Although the nutritional value may undergo some changes by the presence or absence of phenolic compounds such as condensed tannins. The objective of this study was to evaluate the chemical composition, fermentation quality and gas production in vitro in sorghum silage added with different levels of pigeon pea. The study was divided into two experiments. The first study (Chapter 3) evaluated the effects of the addition of pigeon pea grass on the chemical composition and fermentation of sorghum silage. The treatments were: T1 - silage with 100% sorghum, T2 - silage with 25% of pigeon pea and sorghum 75%, T3 - silage with 50% of pigeon pea and sorghum 50%, T4 - silage with 75% pigeon pea and 25% of sorghum and T5 - silage with 100% pigeon pea. The parameters of chemical composition and fermentation of the silage were: dry matter (DM), crude protein (CP), neutral detergent fiber (NDF), acid detergent fiber (ADF), total carbohydrates (TCHO), ash, total phenolics (TP), total tannins (TT), condensed tannins (CT), pH, buffer capacity (BC), losses of fermentation and lactic acid. The addition of pigeon pea showed linear effect (P <0.01) in silage for DM, CP, NDF, ADF, TP, as well as the levels of CT and fermentation losses in DM of silage. As for the contents of TCHO, CT and MM there were quadratic responses (p <0.01) among silages. The results observed that, inclusion of 25, 50 and 75% pigeon pea, based on fresh weight, are sufficient to improve the nutritional value and to achieve better fermentation pattern of sorghum silage. The second study (Chapter 4) evaluated the production of gases, methane, DM degradability and degradability of OM in silage sorghum with increasing levels of pigeon pea using the technique of bioassay gas production. Five types of grain sorghum silage with increasing levels (0, 25, 50, 75 and 100%) of pigeon pea were used as substrates and evaluated by gás production technique. There were no significant differences with and without the presence of PEG within each level using regression, for (GP, CH4 and DMD), but there were significant effect for using of contrast for the variables (GP, CH4 and OMD). No significant difference was observed for the increments for the variables (GP and CH4,). On the other hand GP was more increase in the level of 25% of pigeon pea in the presence of PEG. Compared with the other levels of pigeon pea the level 50% showed higher emissions of methane. In the presence of PEG,DMD and OMD Showed higher percentage on the substrate with 100% of pigeon pea . it can be concluded that ,the addition of pigeon pea in sorghum silage increased the PC content and decreased the NDF, implying a higher nutritive value of silages, but the tannins need to be monitored for future experiments in vivo

As técnicas in vitro de produção de gases são usualmente empregadas em pesquisas na nutrição de ruminantes com a finalidade de simular a fermentação ruminal, possuindo diversas vantagens como facilidade de adoção, repetibilidade, uso minimizado de animais e baixo custo. Para tanto, é necessário a coleta de conteúdo ruminal, a qual geralmente é obtida com o uso de animais fistulados no rúmen, no entanto este tipo de cirurgia esta cada vez mais contestada. Frente a esse duelo, há um crescente interesse científico por pesquisas que forneçam alternativas ao inóculo ruminal. Sendo assim, o objetivo deste trabalho foi avaliar o uso de inóculo fecal submetidos à pré-incubações em substituição ao inóculo ruminal de bovinos na técnica in vitro de produção de gases em bioensaio de metanogênese (24 h) e de cinética fermentativa (72 h). Como doadores de inóculos ruminal e fecal foram utilizadas quatro novilhas Nelore portadoras de cânulas ruminal. O delineamento experimental utilizado foi o de blocos casualizados, com cinco tratamentos e quatro blocos com duas réplicas analíticas para cada repetição. Sendo os tratamentos os inóculos: conteúdo ruminal (CR), fezes sem pré-incubação (F0), e fezes com 12, 24 e 36 h de pré-incubação (F12, F24 e F36, respectivamente). Foram avaliados os efeitos da pré-incubação das fezes quando utilizado como inóculo fecal sobre a estimativa da degradabilidade ruminal, produção de metano e parâmetros de fermentabilidade. Os dados foram analisados pelo programa estatístico SAS 9.3 verificando a normalidade dos resíduos e a homogeneidade das variâncias, em seguida foram realizadas as comparações das médias pelo teste de Tukey. Em ambos os bioensaios (24 e 72 horas), os inóculos fecais pré-incubados por 24 ou 36 horas mostraram-se bom substituto ao inóculo ruminal para análises de degradabilidade in vitro da matéria seca e orgânica. Para as variáveis produção de total de ácidos graxos, perfil de ácidos graxo de cadeia curta, relação acético:propiônico e nitrogênio amoniacal, o inóculo sem pré-incubação (FE0) foi o que mais se aproximou do inóculo referência. Para as produções de gases, produção de metano e fator de partição da matéria seca e matéria orgânica as fezes não foram eficientes.
The in vitro techniques of gas production are usually used in ruminant nutrition research with the purpose of simulating ruminal fermentation. This technique has several advantages such as ease of adoption, repeatability, minimized use of animals and low cost. Therefore, is necessary the collection of ruminal content, which is usually obtained with the use of fistulated animals in the rumen, however this type of surgery is increasingly challenged. Faced with this duel, there is a great scientific interest in research that provides alternatives to the ruminal inoculum. The objective of this research was to evaluate the use of fecal inoculum submitted to preincubation to replace rumen inoculum of Nelore in the in vitro technique of gas production in bioassay of methanogenesis (24 h) and fermentative kinetics (72 h). Four Nellore carrying ruminal cannula were donors of ruminal content and feces. The experimental design was a randomized block, with five treatments and four blocks with two analytical replicates for each replicate. The treatments were the inocula: ruminal contents (RC), faeces without preincubation (F0), and faeces with 12, 24 and 36 hours of preincubation (F12, F24 and F36, respectively). Estimates of ruminal degradability, methane production and ruminal fermentability were evaluated. The data were analyzed by the statistical program SAS 9.3 verifying the normality of the residues and the homogeneity of the variances, the averages were compared by the Tukey test. In the two bioassays (24 and 72 hours), the fecal inocula preincubated for 24 or 36 hours were good substitute for the ruminal inoculum in analyzes of in vitro degradability of dry and organic matter. For the variables production of total fatty acids, short chain fatty acid profile, acetic: propionic and ammoniacal nitrogen, the inoculum without pre-incubation (FE0) approached the reference inoculum. For gas production, methane production and partitioning factor of dry matter and organic matter were not efficient.

Com o objetivo de estudar a espécie bubalina quanto ao desempenho de machos bubalinos do nascimento ao abate em regime de pastejo e as características de carcaça em dois pesos de abate, assim como o metabolismo ruminal de dietas com diferentes níveis de proteína e energia e a produção de gases in vitro, o presente trabalho apresenta-se avaliações feitas em quatro partes. A parte 1 foi realizada com búfalos em crescimento criados à pasto, do nascimento até atingirem dois pesos distintos de abate (517 e 568 kg). Avaliações do desempenho foram realizadas com medição do peso vivo, perímetro torácico, altura de cernelha e comprimento corporal e as avaliações das características da carcaça e carne com determinação do rendimento de carcaça quente e fria, perda no resfriamento, peso da gordura, peso do fígado, temperatura e pH da carcaça, área de olho de lombo, espessura de gordura subcutânea, marmorização, maciez e coloração. A segunda parte avaliou dietas com três níveis de proteína (9%, 12% e 15%) no metabolismo ruminal. Os Itens analisados foram: consumo de nutrientes, pH, amônia e ácidos graxos voláteis no rúmen e degradabilidade in situ. Na parte 3, foram avaliadas dietas com dois níveis de proteína (9 e 15%) e dois de energia (65 e 69% NDT) no metabolismo ruminal. Além dos Itens avaliados na parte 2 foram ainda analisados a digestibilidade com uso de marcador, taxa de passagem de liquido ruminal e volume do rúmen e síntese de proteína microbiana. Na última parte foi realizada avaliação de produção de gases in vitro com estudo da cinética da degradabilidade in vitro no tempo de 72 horas. Animais abatidos com diferentes pesos apresentaram desenvolvimento ponderal diferenciado desde o início do crescimento. Não houve diferença entre os dois grupos de animais nas características de carne e carcaça, mas os búfalos abatidos mais pesados (568 kg) apresentaram maior deposição de gordura interna. Níveis de proteína de 9%, 12% e 15% não influenciaram na degradabilidade in situ dos nutrientes e no pH ruminal. A concentração de amônia e AGV foram maiores com níveis de 15% de proteína na dieta. Os níveis de energia (alta ou baixa) combinados com teores de proteína (alto ou baixo) e as correlações entre os níveis de energia e proteína não promoveram efeitos significativos sobre o pH ruminal concentração de amônia, taxa de passagem de líquido e volume ruminal em búfalos, entretanto, dieta com teor de 15% de proteína bruta, independente dos níveis de energia na dieta apresentaram melhores degradabilidades efetivas dos nutrientes. Os níveis de energia não influenciaram significativamente na concentração amônia ruminal ao contrário dos níveis de proteína em que a maior quantidade de proteína na dieta produziu maior concentração de amônia. Não houve diferença significativa na taxa de passagem e volume ruminal entre as quatro dietas fornecidas aos animais. Dietas com diferentes níveis de energia e proteína não influenciaram na qualidade do inóculo para a produção de gases in vitro.
With the aim of studying the buffalo on the performance of males from birth to slaughter in buffalo grazing and carcass characteristics in two slaughter weights, as well as the metabolism of diets with different levels of protein and energy and the production of gases in vitro, this work presents evaluations conducted in four parts. Part 1 was performed with buffalo raised in pasture from birth until they reach two different slaughter weights (517 and 568 kg). Performance assessments were performed with measurement of body weight, chest girth, height and body length and evaluations of carcass characteristics and meat with determining the hot and cold carcass, the cooling loss, fat weight, liver weight, temperature and pH of the carcass, ribeye area, fat thickness, marbling, tenderness and color. The second part evaluated diets with three protein levels (9%, 12% and 15%) on rumen metabolism. Items discussed were the amount of nutrients, pH, ammonia and volatile fatty acids in the rumen and degradability in situ. In Part 3, were evaluated diets with two protein levels (9 and 15%) and two energy (65 and 69% of TDN) on rumen metabolism. Besides the items evaluated in Part 2, were also analyzed the digestibility, passage rate and ruminal volume and rumen microbial protein synthesis. In the last part was done evaluation of gas production in vitro with study of the kinetics of degradation in 72 hours. Animals slaughtered at different weights showed differential weight performance since the beginning of growth. There were no differences between the two groups of animals on meat and carcass characteristics, but the buffaloes slaughtered heavier (568 kg) had higher deposition of internal fat. Protein levels of 9%, 12% and 15% did not influence the in situ degradability of nutrients and rumen pH. The concentration of ammonia and VFA levels were higher with 15% protein diet. Energy levels (high or low) combined with protein levels (high or low) and the correlations between the levels of energy and protein did not cause significant effects on rumen pH, ammonia concentration, liquid passage rate and ruminal volume in buffalo, however, dietary content of 15% crude protein, independent of the energy levels in the diet showed better effective degradability of nutrients. Energy levels did not significantly modify the rumen ammonia concentration unlike the protein levels where in the higher protein diet resulted in higher ammonia concentration. There was no significant difference in passage rate and ruminal volume between the four diets fed to the animals. Diets with different levels of energy and protein did not influence the quality of inoculum for the gas production in vitro.

Mestre em Ciências Veterinárias
Os efeitos benéficos da adubação com silício (Si) têm sido observados em várias espécies vegetais, especialmente quando estas são submetidas a estresse, seja ele biótico ou abiótico. Aumentos de produtividade e resistência a pragas e doenças estão entre os principais benefícios do Si para as plantas que o absorvem e o acumulam na parte aérea, uma das possíveis razões para maior adaptabilidade e resistência do capim braquiária nas áreas de acidez e baixa fertilidade do solo das regiões do cerrado brasileiro. Objetivou-se avaliar o efeito da adubação superficial com silicato e calcário sobre algumas características químicas do solo; concentração de Si na folha, produção de matéria seca, composição bromatológica, produção de gases e degradabilidade ruminal in vitro da gramínea Brachiaria decumbens. Para tal foi utilizado o delineamento em blocos casualizado, com cinco doses de silicato: 0, 880, 1320, 1760 e 2640 kg.ha-1 e uma dose de 1760 kg.ha-1 de calcário, aplicados superficialmente com leve incorporação em pastagem de Brachiaria decumbens na região do Triângulo Mineiro. Foram realizados cinco cortes na parte aérea da braquiária aos 45, 75, 103, 166 e 382 dias após a instalação do experimento, sendo analisadas as variáveis: matéria seca, concentração de Si foliar e Si acumulado na parte aérea. O material proveniente do terceiro corte foi usado nas avaliações bromatológicas, de produção de gases e degradabilidade ruminal in vitro. Procederam-se também duas amostragens de solo nas profundidades de 0-10, 10-20 e 20-40 cm aos 5 e 12 meses após a implantação do experimento, para avaliar o pH (CaCl2), Ca, Mg e Si no solo. Os resultados demonstraram que o silicato não afetou a produção de matéria seca, porém aumentou as concentrações de Si na parte aérea da planta, comprovando ser a Brachiaria decumbens uma espécie acumuladora de Si. O silicato também elevou os teores de Si e Ca no solo, entretanto o mesmo não se mostrou significativo para os valores de pH e Mg no solo. Com relação à comparação entre o silicato e o calcário este não apresentou diferenças entre as médias estudadas, tanto na análise das variáveis relacionadas ao solo como à parte aérea da braquiária. Não houve efeito da concentração de Si na folha sobre a composição bromatológica, a não ser na fração mineral do material estudado. A presença do Si em altas concentrações na folha da gramínea Brachiaria decumbens (12,7 g.kg-1 na dose testemunha e 16,0 g.kg-1 na dose de 2640 kg.ha-1 de silicato) não afetou a cinética de fermentação na produção de gases ou sua degradabilidade ruminal in vitro.

La " biotransformation ruminale " est un concept qui regroupe l'ensemble des réactions se produisant dans le rumen (dégradation, synthèse et conversion). Ces réactions sont pilotées par trois forces motrices majeures : les lois de la cinétique chimique, de la thermodynamique et de la dynamique des populations microbiennes. Cette thèse a pour objectif d'étudier l'impact d'un facteur alimentaire (pourcentage de concentrés incorporés dans la ration, supplémentation en huile) sur le fonctionnement du rumen et la biotransformation ruminale des constituants alimentaires en termes de dynamique et d'intensité. Cette thèse a combiné trois types d'approches : un essai in vivo sur des chèvres en milieu de lactation, deux essais in vitro (méthode du gaz-test) et une approche de modélisation mécaniste. In vivo, les réactions de biotransformation ont été évaluées par un suivi de la dynamique postprandiale et des mesures de bilans duodénaux. De plus, nous avons étudié l'influence réciproque des phénomènes ruminaux et de l'animal-hôte (comportement d'ingestion, métabolisme, paramètres zootechniques, et qualité du lait) sur le long terme (6 semaines). Nos résultats sont en accord avec la plupart des études antérieures effectuées chez la chèvre ou la vache laitières. Les modifications du comportement d'ingestion observées après 6 semaines avec le régime riche en concentrés ont eu un effet sur les phénomènes digestifs ruminaux. Les flux duodénaux d'acides gras ont expliqué les profils en acides gras du lait. Les études in vitro ont donné des résultats très cohérents par rapport à l'in vivo lorsque les animaux donneurs recevaient les régimes incubés. Enfin, nous avons développé un modèle mécaniste de fonctionnement de rumen in vitro décrivant de manière spécifique les lois physico-chimiques expliquant les dynamiques d'évolution du pH et de formation de gaz. Ce modèle aboutit à des résultats satisfaisants et pourrait être intégré à un modèle de rumen plus complet. La modélisation semble être le meilleur moyen pour intégrer toutes les réactions de biotransformation observées lors d'expérimentations.

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As a result of pasture seasonality during the Brazil dry season forages do not provide sufficient amounts nutrients, to the animals production rates and because of this it is recommended the retention of quality forage as silage. Always aiming at the low cost of silage production, alternatives arise for forage conservation with the addition of wastes, allowing improvement of the chemical characteristics of the silage mass. Aiming chemical-bromatological determination, pH, gas production, recovery of DM, titratable acidity, ammonia nitrogen, aerobic exposure and in vitro digestibility of sorghum silage added with soybean crop residue, performed a experiment at the Federal University of Goias, Regional Jataí, characterized by 10 mini-silos containing 1 kg of dry fine sand at the bottom, separated by a silage cotton fabric and fitted with Bunsen valve cap with type. After 50 days, the mini-silos were opened and made the analyzes. For evaluation of aerobic exposure, 500 g silage were separated into plastic buckets capacity 2 L in duplicate, one of which consisted of a mercury thermometer inserted into the mass. These buckets remained in an incubator at 25°C, with measurement of temperature (mercury thermometer and digital thermometer) of 12 in 12 hours to observe the increase of 2°C above ambient temperature. All data analyzes were performed using SAS version 9.3 (2010) a 5% probability program. For the effect of the addition of soybean residue on the compositional characteristics of the silage was considering completely randomized with six replications, and the comparison of levels of addition of soybean crop residue was orthogonal contrast. To evaluate the performance of aerobic exposure, used it as a split plot design, considering the effect of the addition of the residue in the plot and sampling day in the sub-plot. Comparisons between means were performed using the Tukey test. To compare the values of rate stability depending on the type of thermometer (mercury or infra red) was used regression equation between the two estimates, Y (Tdigital) = ß0+ ß1X (Tmercury), using the "t" test, to verify if the slope of the line obtained by regression differs from the ideal straight equality between techniques (Y = X). Also, analysis of variance was performed on the evaluation of the level of waste additions separately for each thermometer.
Em consequência da estacionalidade das pastagens no período seco no Brasil, as forrageiras não fornecem quantidades de nutrientes suficientes em todas as épocas do ano para manter os índices produtivos dos animais, sendo recomendável a conservação da forragem de qualidade na forma, por exemplo, de silagem. Visando o baixo custo no processo de ensilagem, alternativas surgem para a conservação de forragens com a adição de resíduos ou co-produtos agroindustriais que possibilitem a melhoria das características químicas da massa ensilada. Objetivando a determinação químico-bromatológica, o pH, a produção de gás, a recuperação da MS, a acidez titulável, o nitrogênio amoniacal, a estabilidade aeróbia e a digestibilidade in vitro da silagem de sorgo com diferentes níveis do resíduo da colheita da soja, foi realizado um experimento na Universidade Federal de Goiás, Regional Jataí, pelo uso de 10 minissilos contendo 1 kg de areia fina seca no fundo, separada da silagem por um tecido de algodão e providos de tampa com válvula tipo Bunsen. Após 50 dias, os minissilos foram abertos para a avaliação da estabilidade aeróbia, 500 g de silagem foram separadas em baldes plásticos de capacidade de 2 L em duplicada, sendo que uma era composta por um termômetro com mercúrio inserido na massa. Estes baldes permaneceram em estufa a 25ºC, com aferição das temperaturas (termômetros de mercúrio e digital) de 12 em 12 horas até observação do aumento de 2ºC acima da temperatura ambiente. Todas as análises dos dados foram realizadas no programa SAS versão 9.3 (2010) a 5% de probabilidade. Para o efeito da substituição do resíduo da colheita da soja nas características de composição da silagem foi considerando o delineamento inteiramente casualizado com seis repetições e a comparação dos tratamentos realizada por contraste ortogonal. Para avaliar o comportamento de exposição aeróbia utilizou-se parcela subdividida, considerando o efeito da substituição do resíduo na parcela e o dia de amostragem na sub-parcela. As comparações das médias foram realizadas utilizando o teste de Tukey. Para comparar os valores da taxa de estabilidade em função do tipo de termômetro (mercúrio ou infra vermelho) foi utilizada equação de regressão entre as duas estimativas, Y(Tdigital) = ß0+ ß1X (Tmercúrio), empregando o teste “t”, para verificar se a inclinação da reta obtida pela regressão difere da reta ideal de igualdade entre as técnicas (Y=X). Também, foi realizada análise de variância na avaliação do nível de substituição do resíduo separadamente para cada termômetro.

The general aim of this thesis was to study the effect of lactobacillus inoculants and exogenous fibrolityc enzymes on ensiled forages. The thesis includes the results of three experiments. The first experiment investigated the effects of a microbial inoculum containing homofermentative lactobacillus (hoLAB) ( a strain of Pediococcus pentosaceus and a strain of Lactobacillus plantarum) as maize silage additive, alone (L) or in combination with a pool of fibrolityc enzymes (LE) in comparison with untreated silage (C) on fermentative profile at 2, 5, 40 and 110 days of ensiling, dry matter (DM) losses at the same time points, and multiple points in vitro Gas Production (GP) after 110 days of ensiling. Results evidenced that, the hoLAB inoculant and hoLAB+ enzymes treatments determined a significant effects relative to a shifting of silage fermentation: reduced pH, increased lactic acid concentration and decreased ethanol production; dry matter recovery was also positively affected by the treatments. hoLAB inoculum is also able to affect the rumen fermentability of the silage increasing the potential GP and the fractional rate of gas production during in vitro test. The addition of fibrolytic enzymes to hoLAB inoculant seems instead to inhibit this capacity to increase GP. The second study was performed relative to whole crop cereals silages: in a first part of this study we determined fermentative profile, DM losses, chemical composition, in vitro dry matter digestibility (DMD) and neutral detergent fibre digestibility (NDFD) and in vitro GP of whole crop silages made from wheat (var. Artico and var. Sollario) , triticale (var. Magistral) and wheat–barley-triticale mixture (WesternTM) harvested at two different maturity stages (Early vs Late). In the second part the aim was relative to determine the effects, on the same parameters of the first part, of the addition at ensiling of an inoculum of lactobacillus and fibrolitic enzymes mixture on a selected wheat ( var. Artico) harvested at two different maturity stage in comparison with the untreated silage (C). All forages resulted well preserved. Neutral Detergent Fibre (NDF) content was influenced by maturity stage and crop. NDFD was reduced with increasing of maturity stage (50.5 vs 45.0%, P<0.001). Gas production (GP) at 8 h of incubation was positively influenced by maturity stage (P<0.001), showing a linear relationship with starch content. Inoculum addition reduces dry matter losses during the ensiling period, and seems to slightly reduce the fibre fractions. The significantly higher GP value at 8 h at early stage suggests a release of carbohydrates from fibre fraction to a fraction with higher degradability. From this point of view further investigations would be desirable in order to better clarify the action of the inoculum of lactobacilli and fibrolytic enzymes on the fibre components of the ensiled crop. The third experiment was conducted to investigate the effect of a lactobacillus inoculum (containing a blend of Lactobacillus plantarum , Pediococcus pentosaceus and Lactobacillus brevis) or, two different pool of exogenous fibrolityc enzymes (conteining different concentration of ß-glucanase, Cellulase, Mannanase e Xylanase), alone or in combination, on fermentation characteristics, in situ NDF degradability and in vitro OM Gas production of two maize stove silage harvested at different stage of maturity. The corn plants without cobs were harvested at two different stages of physiological maturity (dought and advanced dought) in order to test the action of the treatments on two fibrous matrices with a supposed diversity of fiber degradation due to the different degree of lignification (High vs. Low). The ensiling of two different fibrous matrices has been done in 2 liters microsilos from, which were then stored at controlled temperature for 110 days. The primary effect of all the treatments was in modifying the fermentative profile of the silages after 110 days of incubation, specially increasing the lactic acid concentration and reducing the ethanol production . In addition, in vitro ruminal fermentation indicated that LAB have a potential for increasing gas production, whereas this is not the case of enzymes treatments. The combination of LAB and enzymes resulted in an higher GP than control only for the highest dosage of enzymes, but without any benefit compare to LAB treatment. Results suggest that microbial inoculants can consistently improve fermentation profile and positively alter ruminal in vitro fermentation and thus potentially improve animal performance. Enzymes, alone seems to have an effect just on the fermentative process during the ensiling period, whereas the combination of LAB and enzymes need to be further investigated in order to explore better the interactions between the two additives.

Foi realizado no Laboratório de Ciências Agrárias da Faculdade de Zootecnia e Engenharia de Alimentos, um bioensaio de fermentação in vitro para avaliar a inclusão de doses crescentes de ureia de liberação controlada (ULC) em lâminas foliares de Brachiaria brizantha cv. Marandu em duas idades de rebrotação. Amostras colhidas em duas idades de rebrotação (28 e 65 dias, S28 e S65, respectivamente) foram incubadas em frascos com doses crescentes de ureia de liberação controlada (ULC - D0, D5, D10 e D20), em três inóculos distintos. O delineamento experimental foi em blocos casualizados fatorial 2 x 4. Foram realizadas análise de regressão e comparação entre médias pelo teste Tukey 5%. Durante 96 horas de fermentação foram colhidas s informações de leitura da produção de gases (tempos 4, 8, 12, 18, 24, 30, 36, 48, 60, 72, 84 e 96 h), concentração de N-NH3 (tempos 6, 12, 24, 48 e 96 h), e AGCC no fluido ruminal (tempos 24 e 48 h), pH (tempo 0 e 96h) e desaparecimento da FDN e MO (tempos 24, 48 e 96 h). Foram calculadas e analisadas as variáveis matemáticas geradas a partir do modelo exponencial indicando tempo de colonização (L), assíntota da curva de produção de gases (A), taxa de fermentação (µ), relação entre os tempos 48 e 96 h (R1), relação entre o tempo 96 h e Assíntota A (R2), t ½ da curva de produção de gases, Fatos de Partição MOD e AGCCtot com a produção acumulada de gases. Não foi observado efeito de doses sobre a produção total ou fracionada de AGCC em 24 e 48 horas de fermentação. Houve efeito de substrato para a síntese de AGVCR - valerato, isovalerato e outros, sendo maiores para o substrato S28, em 24 e 48 horas, indicando maior fermentação proteica. Em 24 horas, frascos contendo substrato S28 mantiveram níveis mais baixos de N-NH3 no fluido ruminal que aqueles contendo substrato S65 para doses 0, 5 e 10. Em 48 horas, as concentrações de N-NH3 indicam que a fermentação do substrato S65 foi mais eficiente na utilização de N-NH3, com concentrações significativamente inferiores de N-NH3 no fluido. O pH encontrado ao final da incubação indica adequação do processo fermentativo favorecendo microrganismos celulolíticos no fluido ruminal. Em relação à cinética fermentativa, S28 apresentou menor tempo de colonização, menor potencial de produção de gases e maiores taxas de fermentação (µ) em todos os tempos estudados. DIVMO e DIVFDN apresentaram efeito cúbico de doses para o substrato S28 durante as 24 horas de incubação. Embora o substrato S65 tenha apresentado taxa fermentativa mais lenta e apresentado menor degradação de MO e FDN nos períodos de 24, 48 e 96 horas, foi mais eficiente quando avaliado quanto ao Fator de Partição. Em conclusão, o fornecimento de Ureia de Liberação Controlada em lâminas foliares de capim-marandu foi mais eficiente na redução de N-NH3 em substratos com 65 dias de idade de rebrotação entre 24 e 48 horas de fermentação, que pode indicar maior conversão em proteína microbiana.
Was conducted at the Laboratory of Agricultural Sciences, Faculdade de Zootecnia e Engenharia de Alimentos, a in vitro fermentation bioassay to assess the inclusion of increasing doses of urea slow-release ( USR ) in leaf blades of Brachiaria brizantha cv. Marandu in two regrowth ages. Samples collected in two regrowth ages (28 and 65 days, S28 and S65, respectively) were incubated with increasing doses of slow-release urea ( USR - D0, D5, D10 and D20 ), in three different inocula. The experimental design was a randomized block factorial 2 x 4. Regression analysis and comparison of means by Tukey test 5 % were performed. During 96 hours of fermentation were reading information by gas production (4, 8 ,12, 18, 24 ,30, 36, 48, 60, 72, 84 and 96 h), concentration of NH3-N ( 6, 12, 24, 48 and 96 h ), and SCFA in ruminal fluid (24 and 48h ), pH (time 0 and 96 h ) and disappearance of NDF and OM (24, 48 and 96 h ). Were calculated and analyzed the mathematical variables generated from the exponential model indicating colonization time ( L ), asymptote of gas production ( A), fermentation rate (µ), relationship between times 48 and 96 h ( R1 ), relationship between time 96 and asymptote A (R2), t½ of the gas production curve, Factors of Partition from MOD, FDNcD and AGCCtot with the total gas production. No dose effect was observed on total production of SCFA and fractionated at 24 and 48 hours of fermentation. An effect of substrate for the synthesis of AGVCR - valerate, isovalerate and others being higher for substrate S28, 24 and 48 hours, indicating higher protein fermentation. In 24 hours, flasks containing substrate S28 maintained lower levels of NH3-N in rúmen fluid than those containing substrate S65 for doses 0, 5 and 10. Within 48 hours, the concentrations of NH3-N indicate that fermentation substrate S65 was in more efficient use of NH3-N, with significantly lower concentrations of NH3-N in the fluid. The pH found at the end of the incubation indicates suitability of the fermentation process favoring cellulolytic microorganisms. Regarding the fermentation kinetics, S28 showed lower colonization time, less potential for gas production and higher fermentation rates ( µ ) at all time points. DIVMO DIVFDN and had a cubic effect doses for the substrate S28 at 24 hours of incubation. Although the substrate S65 has shown slower fermentation rate, and showed less degradation of OM and NDF in periods of 24, 48 and 96 hours, was more efficient when assessed for Factor Partition. On 24 and 48 hours of incubation was more efficient in the degradation of OM and NDF. At 96 hours remained greater efficiency for degradation of NDF, however, no significant differences for the degradation of MO. In conclusion, the supply of urea slow-release in leaf blades of Marandu-grass was more effective in reducing NH3-N substrates 65 days old regrowth between 24 and 48 hours of fermentation, which may indicate higher conversion protein microbial.

General aim of this thesis was to study canola expellers (CE) extracted by cold pressing in a small plant (on farm) and to evaluate the validity to use this by-product in ruminant feeding. The thesis includes the results of four experimental contributes: the first one aimed to evaluate the stability of CE at different times and temperatures of storage in order to determine if the conditions usually found in the farms, especially during the hot season, can result in changes in fatty acids profile and in some oxidative parameters. Results found that under different temperatures (12, 24, and 36°C) and times of storage (10, 20, and 30 d), CE maintained a good oxidative stability, as evidenced by low peroxide values (< 10 mEq/kg fat) in all samples collected, by negative response for Kreis test and by low changes in fatty acids profile. From these results it could be hypothesized that the storage of these by-products did not change the characteristics of the lipid fraction. In the second contribute in vitro gas production (GP) values obtained from the incubation of CE, whole soybean seed (WSS) and soybean meal (SBM) were compared, incubating feed samples with two media containing N-rich buffer or N-free buffer, in order to compare the effect of the availability of feed as unique protein source. Results of the experiment showed that CE is an easily degradable protein source. In the first hours of incubation with limiting N availability, higher gas production was recorded compared to the two soybeans. On this basis, CE could be interesting in diets at low protein content, currently suggested in order to reduce nitrogen excretion. No toxic effects on the microbial yield were observed during the fermentation of the three different feeds. The third contribute compared four diets formulated for beef cattle, based on corn silage and containing WSS or CE as protein sources at two different inclusion levels, in order to obtain 15 and 11 % CP of DM in the diets. Diets were tested using Rusitec fermenter. Compared to WSS, CE provided greater NDF degradability (P < 0.01), produced less acetate and propionate (P < 0.001) but more butyrate and branched-chain VFA. The total VFA production was similar for the two protein sources. With regard to nitrogen balance, CE showed greater 15N enrichment in the non-ammonia N (P < 0.01) and nominally lower values of microbial N derived from ammonia compared to WSS (P = 0.06). At high inclusion level, the 15N enrichments for ammonia N, non-ammonia N and total bacteria N were also greater than observed at low inclusion levels (P < 0.001). In conclusion, the two feeds showed different fermentation patterns. The manipulation of dietary protein level seemed to lead primarily to a variation of bypass protein, without effects on the synthesis of microbial N. In the fourth contribute the same diets tested in Rusitec fermenter (third contribute) were evaluated using RF system (Ankom Technology, Macedon, NY, USA) in order to evaluate their gas production kinetics. Results showed that both NDFd and TDMd values were greater (P<0.05) for CE diets compared to WSS, confirming the results obtained with Rusitec and as expected were lower (P=0.04) for L compared to H diets. Compared to WSS, CE inclusion in the diets increased the rate of GP (P<0.05;) but did not affect the total amount of GP. The reduction of CP level in the diets from 15 to 11% decreased the rate of GP without effects on total GP. Ammonia content increased (P<0.01), as expected, with the level of dietary CP. In conclusion, when diets with low CE levels are used, the inclusion of rapeseed cake in replacement to soybean seeds could improve the rate of degradation during the first hours of fermentation. In general CE obtained by cold extraction on farm could be an interesting feed in ruminant feeding with economical and environmental benefits.
Obiettivo generale di questa tesi è stato quello di studiare e valutare il panello di colza (CE) estratto a freddo in impianti aziendali di piccole dimensioni per un potenziale utilizzo nell'alimentazione dei ruminanti. Nella tesi sono riportati i risultati di quattro prove sperimentali: nel primo contributo è stata valutata la stabilità  della frazione lipidica del CE a temperature diverse e per diversi periodi di tempo al fine di valutare se la conservazione in condizioni anche particolari (durante la stagione estiva) in azienda, possa modificare il profilo degli acidi grassi e alcuni parametri di ossidazione lipidica. I risultati hanno evidenziato che a diverse temperature (12, 24, e 36°C) e tempi di stoccaggio (10, 20, e 30 d), CE ha mantenuto una buona stabilità ossidativa, come evidenziato dai bassi valori del numero di perossidi (<10 mEqO2/kg grasso), dal test di Kreis sempre negativo, e dalle scarse variazioni del contenuto di acidi grassi. Da questi risultati preliminari si può ipotizzare che lo stoccaggio aziendale per i panelli sottoprodotti ottenuti dal colza in azienda, non determina grosse variazioni della componente lipidica. Nel secondo contributo sono state valutate, in vitro, le produzioni di gas prodotti da campioni di CE e da semi di soia integrale incubando i questi alimenti con due differenti media: uno ricco in a N e uno senza N in modo da confrontare l’andamento delle fermentazioni quando l’unica fonte di N risulta l’alimento. I risultati hanno evidenziato che CE è una fonte proteica rapidamente degradabile; in caso di diete ipoproteiche come quelle suggerite per ridurre l’escrezione azotata, la sua inclusione potrebbe favorire l'€™attività  microbica ruminale. Non sono sati rilevati effetti tossici sulla microflora ruminale durante la fermentazione dei due alimenti. Nel terzo contributo sono state confrontate in vitro quattro diete per bovini da carne a base di silomais con 2 livelli di inclusione di CE e WSS, in modo da ottenere un livello di proteina grezza paria al 15% e all’11% PG sulla sostanza secca. In questa prova è stato utilizzato il sistema semicontinuo di fermentazione Rusitec. Le diete contenenti CE hanno mostrato una maggior (P <0.01) degradabilità  dell'€™NDF, e prodotto meno (P <0.01) acetato e propionato ma più butirrato e acidi grassi ramificati. La produzione totale di AGV non è risultato diversa tra le due fonti proteiche. Il bilancio dell’N ha mostrato un maggior quantità (P <0.01) di arricchimento in15N nell’azoto non ammoniacale e valori tendenzialmente (P = 0.06) inferiori di N microbico derivato dall'€™uso di ammoniaca rispetto alle diete con inclusione di WSS. Nelle diete ad alto livello di inclusione i valori di arricchimento in 15N delle varie frazioni azotate sono risultati, come atteso, più alti (P <0.01) rispetto a quelle a basso livello di inclusione. In conclusione i due supplementi hanno mostrato andamenti fermentativi molto diversi. I due diversi livelli di inclusione hanno influito principalmente sulla disponibilità di proteina by pass senza effetti sulla sintesi microbica. Nel quarto contributo sono state testate, con la tecnica della gas production, le stesse quattro diete usate nel precedente esperimento. E’ stato utilizzato il sistema RF Ankom® per testare la cinetica della produzione di gas nel corso della fermentazione. I risultati hanno mostrato che sia i valori di degradabilità dell'NDF che della SS sono stati maggiori (P < 0.05) per le diete contenenti CE rispetto a quelle con WSS e, come atteso, sono risultati inferiori nella diete a basso livello di inclusione delle due fonti proteiche. Le diete CE sono state caratterizzate da una produzione oraria di gas superiore (P < 0.05) in, ma non è variata la quantità totale di gas prodotto. La riduzione del livello di CP da 15 all'11% SS ha diminuito il tasso di produzione di gas ma non la quantità totale. Il contenuto di ammoniaca nel liquido ruminale al termine dell’incubazione è risultato più alto (P < 0.001) nelle diete ad alto livello di inclusione. Concludendo possiamo affermare che con diete a basso livello di proteina, l'€™uso di CE in sostituzione alla soia, può migliorare la velocità di degradazione durante le prime ore di fermentazione. In generale, il panello di colza ottenuto per estrazione a freddo in azienda potrebbe essere un alimento interessante nell'€™alimentazione dei ruminanti con effetti favorevoli sia dal punto di vista economico che ambientale

A vegetação nativa do sertão nordestino é rica em espécies forrageiras nos estratos herbáceo, arbustivo e arbóreo. Estudos têm revelado que acima de 70% das espécies botânicas da caatinga participam significativamente da composição da dieta dos ruminantes domésticos. Estrategicamente, as espécies lenhosas são fundamentais no contexto de produção e disponibilidade de forragem no semiárido Nordestino. Objetivou-se com este trabalho: (1) Quantificar a composição química bromatológica e os compostos fenólicos de leguminosas nativas; (2) Avaliar as características de degradação ruminal e o efeito biológico de plantas taniníferas baseado na técnica de produção de gás in vitro (bioensaio); (3) Estudar os efeitos de dietas constituídas de forrageiras nativas na síntese de nitrogênio microbiano in vitro com marcador 15N e nos parâmetros de fermentação pela técnica de produção gases. Os resultados quanto à composição química e quantificação dos compostos fenólicos das leguminosas taniníferas catingueira (Caesalpinea bracteosa), aroeira (Astronian urundeuva), leucena (Leucaena leucocephala), jureminha (Desmanthus virgatus) e do capim buffel (Cenchrus ciliaris L.) são apresentados. Estas plantas também foram avaliadas por incubação in vitro, juntamente com feno de alfafa (Medicago sativa) como controle, para avaliar o incremento de gás devido à adição de polietilenoglicol (PEG). As leguminosas apresentaram na produção de gases menor atividade biológica dos taninos com adição do PEG, sendo positivos os coeficientes de correlações entre o incremento na produção de gases na presença do PEG e os parâmetros de produção de metano, demonstrando o potencial destas plantas taniníferas para reduzir a produção de metano ruminal, com destaque para leucena e aroeira, com elevado teor proteic e menores teores de fibras. No capitulo 4 são apresentados os resultados do ensaio in vitro para avaliar os efeitos de dietas constituídas de forrageiras nativas da região de Caatinga do NE Brasileiro na síntese de nitrogênio microbiano, utilizando o marcador 15N; e os parâmetros de fermentação pela técnica in vitro de produção gases. As dietas foram constituídas com as espécies catingueira (Caesalpinea bracteosa), aroeira (Astronian urundeuva), leucena (Leucaena leucocephala), jureminha (Desmanthus virgatus) e capim buffel (Cenchrus ciliaris L.), oriundas de três coletas (Agosto de 2008, Março de 2009 e Agosto de 2009). Dois níveis (50% e 30%) de plantas foram usadas em cada dieta simulando sistema CBL (Caatinga, Capim buffel + Leucena). Em geral, as dietas experimentais apresentaram em sua composição química, elevado teor de proteína bruta baixa concentração de compostos fenólicos. Quando estas dietas foram avaliadas através da técnica de produção de gás in vitro, as dietas mostraram redução na emissão de metano, e os parâmetros fermentativos sugeriram que houve mudanças nas rotas de fermentação das dietas. O uso de leguminosas nativas da caatinga pode ser uma alternativa na região semi-árida, principalmente, oferecendo características favoráveis como: valor nutricional, potencial produtivo e rusticidade. No entanto, a viabilidade, no ponto de vista nutricional pode limitar o uso de algumas espécies, devido à alta concentração de compostos fenólicos, principalmente os taninos condensados.
The native vegetation of Northeastern region of Brazil is rich in forage species in the herbaceous, shrubby and arboreal strata. Studies have revealed that over 70% of botanical species from the caatinga participate significantly in the composition of the diet of domestic ruminants. Strategically, the woody species are fundamental in the context of production and availability of forage in such semi-arid area. The objectives of this work were: (1) to quantify the chemical composition and the phenolic compounds of native legumes form the semi-arid region of Pernambuco; (2) to assess the rumen degradation characteristics and biological effect of such tanninferous plants based on in vitro gas production technique (bioassay); (3) to study the effects of diets consist of the native forage on microbial nitrogen synthesis in vitro using 15N as marker and the parameters of fermentation by gas production technique. Chapter 4 presented the results of the in vitro test to assess the effects of diets consist of native forage of Caatinga region of Brazilian NE upon the synthesis of microbial nitrogen using the 15N as tracer, and fermentation parameters. Diets were formed by the species catingueira (Caesalpinea bracteosa), aroeira (Astronian urundeuva), leucena (Leucaena leucocephala), jureminha (Desmanthus virgatus) e capim buffel (Cenchrus ciliaris L.), from three collections (August 2008, March 2009- August 2009). Two levels (50 and 30%) of the plants were used in each diet simulating CBL system (Caatinga + Buffel Grass + Leucena). In general, the experimental diets presented in their chemical composition high crude protein content and low concentration of phenolic compounds. When these diets were evaluated by the in vitro gas production technique, diets showed reduction of methane emission, and the fermentative parameters suggested that there have been changes of fermentation routes of diets. The use of legumes native to caatinga may be an alternative in the semi-arid region, primarily by offering favorable characteristics as: nutritional value, productive potential and homeliness. However, the viability, in nutritional point of view the use of some species can be limiting, because of high concentration of phenolic compounds in particular the condensed tannins.

Efecto de especias sobre producción de gas en rumiantes
El objetivo de este estudio fue evaluar el efecto de la inclusión de 1, 2 y 3 % de eucalipto (Eucalyptus spp), clavo (Syzygium aromaticum) y menta (Mentha piperita), así como 0.20 ppm de monensina sódica en una dieta para ovinos en finalización sobre la fermentación ruminal y producción de metano in vitro. Se registraron las lecturas de presión y volumen de gas a las 3, 6, 9, 12, 24, 36, 48, 60 y 72 h, evaluando volumen máximo de gas, tasa de producción de gas, fase lag, degradabilidad de la materia seca, CH4, CO2 y ácidos grasos volátiles (AGV). Los datos obtenidos fueron analizados mediante un diseño completamente al azar, comparando las medias con una prueba de Tukey (P<0.05), además de realizar un arreglo factorial 3 x 4, determinando las interacciones entre las tres plantas y los cuatro niveles. Las dietas con monensina sódica y eucalipto presentaron una disminución en el volumen máximo de gas (P=0.0001), así como menor producción de CH4 (P=0.01) y CO2 (P=0.004); la producción de AGV mostró diferencias (P=0.01) en ácido acético con el 1 % de eucalipto, además de menor producción de ácido butírico (P=0.01), mientras que con el 2 % aumentó (P=0.01) el ácido propiónico y se obtuvo una menor relación acético:propiónico. Al emplear eucalipto sin monensina, se presentó una disminución en tasa de producción de gas (P=0.0008), así como menor producción de gas (P=0.0001) y degradabilidad (P=0.0007), por otro lado al emplear menta la fase lag fue menor (P=0.0001) y se observó mayor reducción en CO2 y CH4 (P=0.0001), finalmente la adición del clavo redujo la tasa de producción de gas (P=0.0004). Por lo cual se concluye que el uso de eucalipto al 3 % disminuye el volumen máximo de gas, tasa de producción de gas así como producción de CH4, además de incrementar la producción de ácido propiónico.

The concept which led to the establishment of the research in natural gas hydrate production, was born by Dr. Robert Amin (currently Professor of Petroleum Engineering at Curtin University and Chair of the Woodside Research Foundation) and Alan Jackson of Woodside Energy. The intended research in this field is to establish the viability of utilizing a synthesised natural gas hydrate as a means to allow a cheaper form of transportation of natural gas from the wellhead to the customer in direct competition with liquefied natural gas (LNG). Natural gas exists in ice-like formations called hydrates found on or under sea-beds and under permafrost. Hydrates trap methane molecules inside a cage of frozen water, where the amount of hydrates trapped is dependent on surrounding formation pressure. The amount of natural gas trapped in hydrates is largely unknown, but it is very large. A number of scientists believe that hydrates contain more than twice as much energy as all the world's coal, oil, and natural gas combined, hence making it a viable option of fuel in the 21st century, in a world constantly seeking cleaner sources of energy. The feasibility of production of natural gas hydrates on offshore installations and onshore facilities makes this development a viable option. As such this technology requires detailed research and development in a laboratory environment coupled with a pilot plant construction for commercial operation. Current estimates for onshore based facilities for the production of hydrates show a cost reduction of approximately 25% compared with LNG plants of the same energy capacity.
There are two major issues which require detailed research and development in order to progress this technology. First is the enhancement of the hydrates production by the use of other additives, and second, the continuous production at near atmospheric pressures. Other research related to transport methodology and re-gasification will be essential for the overall success of this technology, however, this work is outside the scope of this research.

The concept which led to the establishment of the research in natural gas hydrate production, was born by Dr. Robert Amin (currently Professor of Petroleum Engineering at Curtin University and Chair of the Woodside Research Foundation) and Alan Jackson of Woodside Energy. The intended research in this field is to establish the viability of utilizing a synthesised natural gas hydrate as a means to allow a cheaper form of transportation of natural gas from the wellhead to the customer in direct competition with liquefied natural gas (LNG). Natural gas exists in ice-like formations called hydrates found on or under sea-beds and under permafrost. Hydrates trap methane molecules inside a cage of frozen water, where the amount of hydrates trapped is dependent on surrounding formation pressure. The amount of natural gas trapped in hydrates is largely unknown, but it is very large. A number of scientists believe that hydrates contain more than twice as much energy as all the world's coal, oil, and natural gas combined, hence making it a viable option of fuel in the 21st century, in a world constantly seeking cleaner sources of energy. The feasibility of production of natural gas hydrates on offshore installations and onshore facilities makes this development a viable option. As such this technology requires detailed research and development in a laboratory environment coupled with a pilot plant construction for commercial operation. Current estimates for onshore based facilities for the production of hydrates show a cost reduction of approximately 25% compared with LNG plants of the same energy capacity.There are two major issues which require detailed research and development in order to progress this technology. First is the enhancement of the hydrates production by the use of other additives, and second, the continuous production at near atmospheric pressures. Other research related to transport methodology and re-gasification will be essential for the overall success of this technology, however, this work is outside the scope of this research.

Molecular spectroscopy at radio wavelengths is a tool well suited for studying the composition and outgassing kinematics of cometary comae. This is particularly true for distant comets, i.e. comets at heliocentric distances greater than a few AU, where the excitation of molecules is inefficient other than for rotational energy levels. At these distances, water sublimation is inefficient, and cometary activity is dominated by outgassing of carbon monoxide.

An observing campaign is presented, where the millimeter-wave emission from CO in comet 29P/Schwassmann-Wachmann 1 has been studied in detail using the Swedish-ESO Submillimetre Telescope (SEST). Coma models have been used to analyse the spectra. The production of CO is found to have two separate sources, one releasing CO gas on the nuclear dayside, and one extended source, where CO is produced from coma material, proposed to be icy dust grains.

Radio observations of many molecules in comet C/1995 O1 (Hale-Bopp) have been carried out in a long-term international effort using several radio telescopes. An overview of the results is presented, describing the evolution of the gas production as the comet passed through the inner Solar system. Spectra recorded using the SEST, primarily of CO, for heliocentric distances from 3 to 11 AU are analysed in detail, also using coma models.

The concept of icy grains constituting the extended source discovered in comet 29P/Schwassmann-Wachmann 1 is examined by theoretical modelling of micrometre-sized ice/dust particles at 6 AU from the Sun. It is shown that that such grains can release their content of volatiles on timescales similar to that found for the extended source.

In this study
gas production by depressurization method from a hydrate reservoir containing free gas zone below the hydrate zone is numerically modeled through 3 dimensional, 3 phase, non-isothermal reservoir simulation. The endothermic nature of hydrate decomposition requires modeling to be non-isothermal
hence energy balance equations must be employed in the simulation process. TOUGH-Fx, the successor of the well known multipurpose reservoir simulator TOUGH2 (Pruess [24]) and its very first module TOUGH-Fx/Hydrate, both developed by Moridis et.al [23] at LBNL, are utilized to model production from a theoretical hydrate reservoir, which is first studied by Holder [11] and then by Moridis [22], for comparison purposes. The study involves 2 different reservoir models, one with 30% gas in the hydrate zone (case 1) and other one with 30% water in the hydrate zone (case 2). These models are further investigated for the effect of well-bore heating. The prominent results of the modeling study are: &
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In case 1, second dissociation front develops at the top of hydrate zone and most substantial methane release from the hydrate occurs there. &
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In case 2 (hydrate-water in the hydrate zone), because a second dissociation front at the top of hydrate zone could not fully develop due to high capillary pressure acting on liquid phase, a structure similar to ice lens formation is observed. &
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Initial cumulative replenishment (first 5 years) and the replenishment rate (first 3.5 years) are higher for case 2 because, production pressure drop is felt all over the reservoir due to low compressibility of water and more hydrate is decomposed. Compared to previous works of Holder [11] and Moridis [22], amount of released gas contribution within the first 3 years of production is significantly low which is primarily attributed to the specified high capillary pressure function.

Decay and accumulation of blanket peat in the Northern Pennine region of England are considered, both in quantitative and qualitative terms. Productivity on the surface of these peat bogs is not unusually high, suggesting that a low decay rate may be responsible for the accumulation of the peat. Considerable study has formerly been made of the aerobic decay processes, at the expense of the parallel anaerobic processes, which have largely hitherto been considered negligible. Yet a current mathematical model of peat accumulation suggests that it is likely to be the anaerobic decay rate which determines the total depth of peat which may accumulate. Further, such models intimate that a very small absolute change in the anaerobic decay rate will have an unexpectedly large effect on the potential steady state depth of peat. The present study concentrates on obtaining measurements of anaerobic decay rates, and on identifying the possible limiting environmental factors of the decay. The design of a sampler to collect gas samples in situ from blanket peat is described. The components of particular interest in the samples are CH4 and C02. Gas concentrations down eight peat profiles at two sites are monitored over two seasons. Simultaneous surface flux measurements above pool, lawn and hummock microhabitats are also made. Water level, temperature, pH, redox potential, depth of the sulphide zone and total sulphide concentration are recorded on each field visit. The results from the gas sample analyses are discussed in relation to the environmental factors and in relation to our present understanding of peat decay rates and their consequences on peat accumulation. The anaerobic decay rate is calculated, and is confirmed to be several orders of magnitude less than that in the overlying aerobic peat. It is shown that the methane is not fossil, but is continually being produced at all depths. Rates of gas production are calculated. Annual methane and carbon dioxide losses from entire peat bogs are calculated to contribute a significant amount to carbon cycling, on a site-specific and global scale.

Natural gas hydrates are solid crystalline substances found in the subsurface. Since gas hydrates are stable at low temperatures and moderate pressures, gas hydrates are found either near the surface in arctic regions or in deep water marine environments where the ambient seafloor temperature is less than 10°C. This work addresses the important issue of geomechanical stability in hydrate bearing sediments during different perturbations. I analyzed extensive data collected from the literature on the types of sediments where hydrates have been found during various offshore expeditions. To better understand the hydrate bearing sediments in offshore environments, I divided these data into different sections. The data included water depths, pore water salinity, gas compositions, geothermal gradients, and sedimentary properties such as sediment type, sediment mineralogy, and sediment physical properties. I used the database to determine the types of sediments that should be evaluated in laboratory tests at the Lawrence Berkeley National Laboratory. The TOUGH+Hydrate reservoir simulator was used to simulate the gas production behavior from hydrate bearing sediments. To address some important gas production issues from gas hydrates, I first simulated the production performance from the Messsoyakha Gas Field in Siberia. The field has been described as a free gas reservoir overlain by a gas hydrate layer and underlain by an aquifer of unknown strength. From a parametric study conducted to delineate important parameters that affect gas production at the Messoyakha, I found effective gas permeability in the hydrate layer, the location of perforations and the gas hydrate saturation to be important parameters for gas production at the Messoyakha. Second, I simulated the gas production using a hydraulic fracture in hydrate bearing sediments. The simulation results showed that the hydraulic fracture gets plugged by the formation of secondary hydrates during gas production. I used the coupled fluid flow and geomechanical model "TOUGH+Hydrate- FLAC3D" to model geomechanical performance during gas production from hydrates in an offshore hydrate deposit. I modeled geomechanical failures associated with gas production using a horizontal well and a vertical well for two different types of sediments, sand and clay. The simulation results showed that the sediment and failures can be a serious issue during the gas production from weaker sediments such as clays.

Natural gas from organic rich shales has become an important part of the supply of natural gas in the United States. Modern drilling and stimulation techniques have increased the potential and profitability of shale gas reserves that earlier were regarded as unprofitable resources of natural gas. The most prominent property of shale gas reservoirs is the low permeability. This is also the reason why recovery from shale gas wells is challenging and clarifies the need for stimulation with hydraulic fracturing. Shale gas wells typically exhibit a high initial peak in the production rate with a successive rapid decline followed by low production rates. Liquid accumulation is common in shale wells and is detrimental on the production rates. Shut-ins of shale gas wells is used as a means to prevent liquid loading and boost the production. This strategy is used in a model-based production optimization of one and multiple shale gas well with the objective of maximizing the production and long-term recovery. The optimization problem is formulated using a simultaneous implementation of the reservoir model and the optimization problem, with binary variables to model on/off valves and an imposed minimal production rate to prevent liquid loading. A reformulation of the nonlinear well model is applied to transform the problem from a mixed integer nonlinear program to a mixed integer linear program. Four numerical examples are presented to review the potential of using model-based optimization on shale gas wells. The use of shut-ins with variable duration is observed to result in minimal loss of cumulative production on the long term recovery. For short term production planning, a set of optimal production settings are solved for multiple wells with global constraints on the production rate and on the switching capacity. The reformulation to a mixed integer linear program is shown to be effective on the formulated optimization problems and allows for assessment of the error bounds of the solution.

Gas hydrates are crystalline compounds made of gas and water molecules. Methane hydrates are found in marine sediments and permafrost regions; extensive amounts of methane are trapped in the form of hydrates. The unique behavior of hydrate-bearing sediments requires the development of special research tools, including new numerical algorithms (tube- and pore-network models) and experimental devices (high pressure chambers and micromodels). Hydraulic conductivity decreases with increasing variance in pore size distribution; while spatial correlation in pore size reduces this trend, both variability and spatial correlation promote flow focusing. Invading gas forms a percolating path while nucleating gas forms isolated gas bubbles; as a result, relative gas conductivity is lower for gas nucleation than for gas invasion processes, and constitutive models must be properly adapted for reservoir simulations. Physical properties such as gas solubility, salinity, pore size, and mixed gas conditions affect hydrate formation and dissociation; implications include oscillatory transient hydrate formation, dissolution within the hydrate stability field, initial hydrate lens formation, and phase boundary changes in real field situations. High initial hydrate saturation and high depressurization favor gas recovery efficiency during gas production from hydrate-bearing sediments. Even a small fraction of fines in otherwise clean sand sediments can cause fines migration and concentration, vuggy structure formation, and gas-driven fracture formation during gas production by depressurization.

Introduction Short-lived isomer 83mKr (T½ = 1.83 h) is an ideal calibration source in several low-energy experiments like or KATRIN (determining the neutrino rest mass, monitoring high voltage stability and investigation of the main spectrometer properties) or XENON (detection of the dark matter). The isomer 83mKr is formed by decay of 83Rb (T½ = 86.2 d) that can be produced predominantly via the reaction 84Kr(p,2n)83Rb by irradiation of natKr (57 % abundance of 84Kr). The design and construction of the new gas target for effective production of radionuclide 83Rb as well as target processing will be shortly described. Material and Methods For the target design, we selected the following criteria: minimizing activation of target components; efficient cooling system allowing higher beam currents; easy handling; high life-time of the target chamber (low impact of the irradiation and radionuclide separation process on the target chamber surface and 83Rb recovery). The target consists of three parts: 1. Water cooled aluminium (alloy EN 6082) mechanical interface for easy connection of the target to the beam line. It also serves as a beam collimator (diameter 9 mm). 2. Holder of He-cooled foils (vacuum separation foil – Havar 0.025 mm, target body window – Ti 0.1 mm). 3. Aluminium (alloy EN 6082) water cooled target body with 150mm long cone-shaped target chamber of the volume 27.1 ml. Internal surface of the chamber is nickel-coated. The target filled with natural Kr of purity 0.9999 and absolute pressure 13 bar was irradiated on the external beam of the isochronous cyclotron U-120M of the NPI AS CR. The proton beam energy was set so that it is decreased after deg-radation in the separation foils to 25.6 MeV. Beam energy loss in the natural Kr gas filling is 9.6 MeV. The target was tested up to 25 µA beam current. After irradiation, the target is left for a week to let the short-lived activation products to decay. Then, 83Rb is washed out from the target walls by two portions of freshly prepared de-ionized water, target is rinsed by high-purity ethanol and dried. The two portions of 83Rb aqueous solution are then connected and activity and radionuclidic purity of the product is determined via γ-spectrometry (HPGe detector). Large-distance sample-detector measurements of the target prior and after the separation are used in order to determine recovery of 83Rb. Results and Conclusion The new gas target for routine production of 83Rb was successfully designed, tested and im-plemented for regular 83Rb production. Six-hour irradiation with 15 µA proton beam resulted repeatedly in ca 300 MBq of 83Rb (EOB). Besides 83Rb, we identified in the separated product also 84Rb (T½ = 32.82 d) at levels ca 31 % of the 83Rb activity (EOB) and 86Rb (T½ = 18.631 d) at levels ca 8 % of the 83Rb activity (EOB). Both radionuclidic impurities do not disturb the use of 83Rb, since none of them emanates any radioactive krypton isotope. Moreover, their relative content decreases in time. Rubidium isotopes are recovered from the target almost quantitatively (98–99 %).

Thesis (M.S.)--West Virginia University, 2000.
Title from document title page. Document formatted into pages; contains xii, 131 p. : ill. (some col.). Includes abstract. Includes bibliographical references (p. 81-82).

Artemisinin is produced in the leaves of Artemisia annua and is currently one of the most valuable antimalarial treatments. A. annua is of Asian origin but many other family members have been identified worldwide. A. annua however, is the only one that produces artemisinin. Synthetic production of artemisinin is not yet feasible, not to mention very expensive and the product yields are relatively low. The aims of this study were threefold: 1) To regenerate callus, cell cultures and plants from genetically modified root cultures of A. afra into which an artemisinin biosynthetic gene was inserted from A. annua 2) To investigate the probability that fungal endophytes are responsible for the production of artemisinin and 3) To establish two fields of high yielding varieties of A. annua plants and evaluate whether artemisinin production of these two locations will remain high. Callus and cell cultures of the genetically modified A. afra root cultures were established, but no shoots have been produced as of yet and this is an on-going investigation. Fungal endophytes were sampled and none of the endophytes produced artemisinin. Five different lines of A. annua were cultivated, successfully grown and harvested. Measurements were taken at different stages of processing, these were compared and analysed using various methods such as height and mass comparisons. Comparisons revealed that the production of artemisinin is correlated to local sets of conditions rather than the variety of individual lines. The genetic potential to produce high quantities of artemisinin appears to have been lost, instead of being maintained. We confirmed that secondary compound production and specifically, artemisinin, is enhanced by certain stress factors on the plants.
Dissertation (MSc)--University of Pretoria, 2013.
gm2014
Plant Science
unrestricted

Natural gas obtained during the extraction of liquid hydrocarbons is often undesired due to the lack of infrastructure to transport the natural gas to an onshore location. As a result the natural gas is often flared causing economic waste and environmental concern. It would therefore be desirable to either convert the natural gas into some other substance which can be transported easily, or transport the natural gas in a liquid state. In that way, new field development will be more financially viable through the use of the extensive infrastructure and technology already in place in the offshore industry for transporting liquid hydrocarbons. It is considered that one feasible way of utilising offshore produced natural gas, is to convert it into synthetic gas (syngas) which can in turn be used to produce gases and fluids such as methanol, ammonia or a synthetic crude oil that can be readily pumped through the same pipelines as the produced oil. For the production of synthetic gas, membrane technology presents an attractive advantage improving conversion efficiency by operating as catalyst support, which then also increases the catalyst dispersion, resulting in optimal catalyst load and complete consumption of oxygen and methane in the partial oxidation. In the present investigation, an enhanced catalyst-dispersed ceramic membrane for low-cost synthesis gas production suitable for gas-to-liquids has been prepared, characterised and tested in a self-designed membrane reactor. The effect of temperature and feed flow rates has been studied and a kinetic model has been developed. In the novel membrane reactor, an active porous layer is located on both sides facing the oxygen and methane containing gas, adjacent is a second active porous layer and is supported by layers with increasing pore radii. Here the active porous layer on the bore side enhances the reaction between permeated oxygen and fuel species. In this study, it has also been demonstrated that the oxygen is activated prior to contacting the methane inside the membrane. This often results in 100% oxygen conversion, CO selectivity higher than 96% and syngas ratio (1-1/2 C O) of 2.2 to 1.8. Another advantage of the developed membrane system is that it can be used in high temperatures (> 1273.15K) and high pressure (80bars) processes with no variation on the flow rates, due to the mechanical strength of the ceramic support used.

Improving methods of hydrocarbon production and developing new techniques for the creation of natural gas storage facilities are critically important for the petroleum industry. This dissertation focuses on two key topics: (1) mechanisms of sand production from petroleum reservoirs and (2) mechanical characterization of caverns created in carbonate rock formations for natural gas storage. Sand production is the migration of solid particles together with the hydrocarbons when extracted from petroleum reservoirs. It usually occurs from wells in sandstone formations that fail in response to stress changes caused by hydrocarbon withdrawal. Sand production is generally undesirable since it causes a variety of problems ranging from significant safety risks during high-rate gas production, to the erosion of downhole equipment and surface facilities. It is widely accepted that a better understanding of the mechanics of poorly-consolidated formations is required to manage sand production; which, in turn, enables the cost effective production of gas and oil resources. In this work, a series of large-scale laboratory experiments was conducted in fully saturated, cohesionless sand layers to model the behavior of a petroleum reservoir near a wellbore. We directly observed several key characteristics of the sand production phenomenon including the formations of a stable cavity around the wellbore and a sub-radial flow channel at the upper surface of the tested layer. The flow channel is a first-order feature that appears to be a major part of the sand production mechanism. The channel cross section is orders of magnitude larger than the particle size, and once formed, the channel becomes the dominant conduit for fluid flow and particle transport. The flow channel developed in all of our experiments, and in all experiments, sand production continued from the developing channel after the cavity around the borehole stabilized. Our laboratory results constitute a well constrained data set that can be used to test and calibrate numerical models employed by the petroleum industry for predicting the sand production phenomenon. Although important for practical applications, real field cases are typically much less constrained. We used scaling considerations to develop a simple analytical model, constrained by our experimental results. We also simulated the behavior of a sand layer around a wellbore using two- and three-dimensional discrete element methods. It appears that the main sand production features observed in the laboratory experiments, can indeed be reproduced by means of discrete element modeling. Numerical results indicate that the cavity surface of repose is a key factor in the sand production mechanism. In particular, the sand particles on this surface are not significantly constrained. This lack of confinement reduces the flow velocity required to remove a particle, by many orders of magnitude. Also, the mechanism of channel development in the upper fraction of the sample can be attributed to subsidence of the formation due to lateral extension when an unconstrained cavity slope appears near the wellbore. This is substantiated by the erosion process and continued production of particles from the flow channel. The notion of the existence of this surface channel has the potential to scale up to natural reservoirs and can give insights into real-world sand production issues. It indicates a mechanism explaining why the production of particles does not cease in many petroleum reservoirs. Although the radial character of the fluid flow eventually stops sand production from the cavity near the wellbore, the production of particles still may continue from the propagating surface (interface) flow channel. The second topic of the thesis addresses factors affecting the geometry and, hence, the mechanical stability of caverns excavated in carbonate rock formations for natural gas storage. Storage facilities are required to store gas when supply exceeds demand during the winter months. In many places (such as New England or the Great Lakes region) where no salt domes are available to create gas storage caverns, it is possible to create cavities in limestone employing the acid injection method. In this method, carbonate rock is dissolved, while CO₂ and calcium chloride brine appear as products of the carbonate dissolution reactions. Driven by the density difference, CO₂ rises towards the ceiling whereas the brine sinks to the bottom of the cavern. A zone of mixed CO₂ , acid, and brine forms near the source of acid injection, whereas the brine sinks to the bottom of the cavern. Characterization of the cavern shape is required to understand stress changes during the cavity excavation, which can destabilize the cavern. It is also important to determine the location of the mixture-brine interface to select the place of acid injection. In this work, we propose to characterize the geometry of the cavern and the location of the mixture-brine interface by generating pressure waves in a pipe extending into the cavern, and measuring the reflected waves at various locations in another adjacent pipe. Conventional governing equations describe fluid transients in pipes loaded only by internal pressure (such as in the water hammer effect). To model the pressure wave propagation for realistic geometries, we derived new governing equations for pressure transients in pipes subjected to changes in both internal and external (confining) pressures. This is important because the internal pressure (used in the measurement) is changing in response to the perturbation of the external pressure when the pipe is contained in the cavern filled with fluids. If the pressure in the cavern is perturbed, the perturbation creates an internal pressure wave in the submerged pipe that has a signature of the cavern geometry. We showed that the classic equations are included in our formulation as a particular case, but they have limited validity for some practically important combinations of the controlling parameters. We linearized the governing equations and formulated appropriate boundary and initial conditions. Using a finite element method, we solved the obtained boundary value problem for a system of pipes and a cavern filled with various characteristic fluids such as aqueous acid, calcium chloride brine, and supercritical CO₂ . We found that the pressure waves of moderate amplitudes would create measurable pressure pulses in the submerged pipe. Furthermore, we determined the wavelengths required for resolving the cavern diameter from the pressure history. Our results suggest that the pressure transients technique can indeed be used for characterizing the geometry of gas storage caverns and locations of fluid interfaces in the acid injection method.

Gas hydrate consists of guest gas molecules encaged in water molecules. Methane is the most common guest molecule in natural hydrates. Methane hydrate forms under high fluid pressure and low temperature and is found in marine sediments or in permafrost region. Methane hydrate can be an energy resource (world reserves are estimated in 20,000 trillion m3 of CH4), contribute to global warming, or cause seafloor instability. Research documented in this thesis starts with an investigation of hydrate formation and growth in the pores, and the assessment of formation rate, tensile/adhesive strength and their impact on sediment-scale properties, including volume change during hydrate formation and dissociation. Then, emphasis is placed on identifying the advantages and limitations of different gas production strategies with emphasis on a detailed study of CH4-CO2 exchange as a unique alternative to recover CH4 gas while sequestering CO2. The research methodology combines experimental studies, particle-scale numerical simulations, and macro-scale analyses of coupled processes.

In the production of boron fibers using CVD technique, boron deposition and dichloroborane formation reactions take place in a reactor. Boron deposition reaction occurs at the surface while formation of dichloroborane is the result of both gas phase and surface reactions. A CSTR type of reactor was designed and constructed from stainless steel to investigate the gas phase reaction kinetics and kinetic parameters of boron fibers produced from the reaction of boron trichloride and hydrogen gases in a CVD reactor. The gases were heated by passing through the two pipes which were located into the ceramic furnace and they were mixed in the CSTR. The effluent gas mixture of the reactor was quenched by passing through a heat exchanger. An FT-IR spectrophotometer was connected to the heat exchanger outlet stream to perform on-line chemical analysis of the effluent gas mixture. Experiments were carried out at atmospheric pressure and a reactor temperature range of 300-600 º
C with different inlet reactant concentrations. The analysis of the FT-IR spectra indicated that the gas phase reaction and the surface reaction started at reactor temperatures above 170 º
C and 500º
C, respectively. It was concluded that reaction rate of the product increased with an increase in the inlet concentration of both reactants (BCl3 and H2) and with an increase in the reactor temperature. The gas phase reaction rate was expressed in terms of a th and b th orders with respect to the inlet concentrations of BCl3 and H2. The activation energy of the gas phase reaction, a and b were found to be 30.156 , 0.54 and 0.64, respectively. The correlation coefficient was 0.9969.

Soot production in gas turbine combustors is not desirable since it is the major source of exhaust smoke emission and its thermal radiation to the combustor liner deteriorates the liner durability. Soot formation involves comparatively slow chemistry and equilibrium can not be applied to soot modelling in the combustor flow field. . The exact sooting process in the combustor is poorly understood given both the complexity and the limited experimental data available. The work reported in this thesis seeks to first develop in-situ techniques for retrieving spatially-resolved soot properties, mainly soot particle volume fraction, from within the combustor and also to apply the measured results to comparisons with predicted soot concentrations. Two probing methods have been demonstrated which also incorporate a laser absorption technique. The sight probe proves to be more reliable in the present measurements. The evaluation of the physical probing techniques in sooty laboratory flames reveals that the flame structure will not be substantially distorted by the probe. The disturbance caused by the probe is localised, a feature which is evident in the reported water flow visualization test. The necessary inert gas purge can be minimised to reduce the local aerodynamic perturbation. The measured soot volume fraction distributions are comparable with sooting levels reported in flame studies in the literature. The peak soot volume fractions are located off-axis, characteristic of the fuel atornization. The measurementsin the primary zone are restricted by the multi-phase character of the flow, where soot absorption can not be readily discriminated from fuel droplet scattering. Measurements are reported over a range of air-fuel ratios, inlet pressures and temperatures. Time-averageds calard istributionsa t the nominald ilution sectionh ave beeno btained in addition to the soot measuremenut sing probe sampling and standard gas analysis. Correlationso f carbond ioxide with mixture fraction reveala clear relationshipa t overall lean conditionsc onsistenwt ith widely usedm odelleda ssumptions.T here are less well-correlated relationshipsb etweent emperaturea ndm ixture fraction, possiblyd ue to the influenceo f scalar fluctuationsa nda lsoo f the scalard issipationr ate. Sootl oadingi n the presentf low conditions is characteristicallylo w, basedo n the mixture fraction ands ootv olumef raction data. Thermal radiation in the visible spectrum shows a distinct narrow band spectra in addition to the soot continuum, which is believed to arise fromC2radical emission. The mean radiation intensities, predictedb y usingt he measuredte mperaturea nds ootc oncentrationre sults,a rei n generallo wer than the measured mean intensities. Temperature fluctuation levels may be particularly influential in some of these calculations. Sootm odellingi n the combustohr asb eenu ndertakenb y applyinga n extendedla minar flamelet concept. The two-equations oot formation model has beenp rimarily developedo n laminar flames. The comparisono f the computationa nd measuremenstu ggeststh at this soot model holds promise in the context of prediction in the combustor. In the absenceo f a satisfactoryt heoreticald escriptiono f the fuel-air burning in the combustor,w heret he liquid kerosinee mployedis replacedb y gaseoups ropane,t he computeds calarp rofiles are inconsistent in some importantr espectsw ith the measuredo nes. This exerts a major effect on the soot predictioni n terms of the quantitatived etail in the computationw, hich is howeverc rucial for the soot model development. The original flow field modelling needs to be improved for the purpose of further soot model refinement.