Dissertations / Theses on the topic 'Forage maize'

Orientador: Carlos Alexandre Costa Crusciol
Coorientador: Rogério Peres Sotatto
Banca: Juliano Carlos Calonego
Banca: Heitor Cantarella
Banca: Rafael Otto
Banca: Aildson Pereira Duarte
Resumo: O sucesso do sistema de plantio direto depende do conhecimento do sistema agrícola como um todo. O uso de gramíneas do gênero Urochloa como planta de cobertura resulta em lenta decomposição do material orgânico devido à alta produção de matéria seca e alterações nos microrganismos do solo, em particular nos processos biológicos relacionados ao nitrogênio (N). Como o N é um nutriente presente nas principais reações bioquímicas em plantas e microrganismos, o manejo deste nutriente requer atenção especial. Portanto, este trabalho de pesquisa teve como objetivo melhorar a eficiência do uso do manejo do N. O principal objetivo foi avaliar o impacto do adubo nitrogenado aplicado nas duas espécies de gramíneas ou nos seus resíduos para suprir a demanda e aumentar a produtividade de grãos do milho no sistema plantio direto. O experimento de campo foi conduzido durante três anos, no qual Urochloa brizantha e U. ruziziensis foram cultivadas com 4 manejos da adubação nitrogenada. Os manejos da adubação nitrogenada foram: (i) controle (zero aplicação de N), (ii) N aplicado 35 dias antes da semeadura do milho (35 DAS), (iii) N aplicado 1 dia antes da semeadura do milho (1 DAS), e (iv) método convencional (N aplicado em cobertura no crescimento do milho), com a dose de 120 kg ha-1 de N da fonte sulfato de amônio. A hipótese no Capítulo 1 de que o N aplicado nas plantas de cobertura ou nos resíduos destas plantas de cobertura poderiam ser substituir a aplicação de N em cobertura do atual método convencional para cultura do milho foi confirmada quando o N foi aplicado na U. brizantha aos 35 DAS ou em seus resíduos 1 DAS e quando o N foi aplicado nos resíduos da U. ruziziensis 1 DAS. Devido aos resultados observados no primeiro capítulo, o Capítulo 2 objetivou avaliar se a aplicação antecipada de N (nas plantas de cobertura ou nos resíduos das plantas de cobertura) e a ...
Abstract: The success of no-tillage system depends on the knowledge of the agricultural system as a whole. The use of grass Urochloa sp. as cover crop in agriculture results in slow organic material decomposition due to high biomass production and changes in soil microbe, in particular in biological processes related to nitrogen (N). Because N is a nutrient present in the main biochemical reactions in plants and microorganisms, N management requires special attention. Therefore, this research aimed to improve N-use efficiency from both agronomic and biological perspectives. The main objectives were to (i) assess the impact of N fertilizer and forage species on maize in the NT system, and (ii) determine the interactions between microbes x N x environmental factors. A field experiment was evaluated, in which palisade grass (Urochloa brizantha) and ruzigrass (U. ruziziensis) grown with four N management, included: (i) control zero-N (no N application), (ii) N applied on green cover crops at 35 days before maize seeding (35 DBS), (iii) N applied on cover crop residues at 1 day before maize seeding (1 DBS), and (iv) conventional method of N applied at sidedressing in maize growth), at a rate of 120 kg N ha-1 as ammonium sulfate. The hypothesis of Chapter 1 that N applied on alive cover crops or cover crop residues could replace N-sidedressing application (conventional method) for maize was confirmed when: (a) N was applied on palisade grass at 35 DBS or its residues at 1 DBS, and (b) N was ... (Resumo completo, clicar acesso eletrônico abaixo)
Doutor

During the last ten years the cultivation of maize in Sweden has increased and is expected to grow further. Most of the maize in Sweden becomes silage which is used to feed animals at farms. Maize has in other countries been shown to be a substrate for growth of mould and especially Aspergillus spp., Fusarium spp. and Pencillium spp. has been reported. Members of all three of these species can, during favorable conditions, produce mycotoxins which can cause a number of different health problems in both animals and man. The aim of this study was to investigate the occurrence of mould and mycotoxins to increase our knowledge of the hygienic quality of Swedish maize silage. Microbiological analyses were made to study the growth of fungi. To analyze for fumonisin B₁, B₂ and zearalenone, HPLC with fluorescence detection was made. The mycotoxins mycophenolic acid, roquefortine C, gliotoxin, penicillic acid, penitrem A, fumitremorgen C and verrucologen were analyzed with LC-MS/MS. The results showed that 47 % of the samples were contaminated with Penicillium spp. and 6 % had growth of Aspergillus fumigatus. A small amount of zearalenone was found in one sample and 0.01ppm of roquefortine C was detected in one sample. The data obtained indicate that Swedish maize silage has a moderate growth of fungi with a very low production of mycotoxins. More studies have to be performed to make more decisive conclusions.

Le maïs occupe une place centrale dans le système fourrager français, son rendement et sa valeur énergétique étant deux critères clés pour l'inscription des variétés hybrides de maïs au catalogue officiel français. Des recherches antérieures ont montré une corrélation directe entre la valeur énergétique et la digestibilité de la matière sèche (MS), influencée par la digestibilité de la paroi, elle-même affectée par le déficit hydrique. Des études sur des lignées de maïs ont montré que le déficit hydrique sévère augmente la digestibilité de la MS et de la paroi, liées à une diminution de la teneur en lignine et à des changements dans sa distribution tissulaire. Cependant, comme la teneur en lignine a déjà été fixée dans les variétés hybrides, elle semble avoir peu de potentiel pour améliorer davantage la digestibilité de la paroi. Pour explorer d'autres cibles et l'impact du déficit hydrique sur ces caractères, ce travail de thèse a été mené dans le cadre du projet Carnot Plant2Pro INRAE-ARVALIS MAMMA MIA. Des variétés de maïs hybrides modernes, représentatifs du marché français actuel (maïs S0-S1 très précoces à précoces), ont été cultivés pendant deux ans dans seize conditions environnementales contrastées, dont six en conditions d'irrigation contrôlée. Tout d'abord, un indice de stress (SID) simple mais robuste a été établi, tenant compte du déficit hydrique du sol et de la température de l'air. Ce SID s'est révélé être un outil crucial en classant les différents environnements, mettant en évidence l'impact d'un stress sévère dû à des températures élevées sur la digestibilité de la MS par rapport à des conditions de stress modéré. Pour être en mesure d'étudier une large gamme de conditions environnementales, plusieurs équations de prédiction par spectroscopie proche infrarouge (NIRS) ont également été développées, capables de prédire de manière robuste et précise des caractères de la paroi et leurs relations, similaires à celles mesurées en biochimie au laboratoire. Bien que ces équations se révèlent suffisamment robustes pour être utilisées dans les programmes de sélection, une vigilance s'impose quant à l'exactitude des prédictions en conditions de stress, en particulier dans le cas des variétés hybrides où la gamme de variation des caractères est souvent limitée. L'ensemble des données obtenues a ensuite permis une analyse multi-échelle, intégrant des caractères agroclimatiques, agronomiques, biochimiques et histologiques, ainsi que des données expérimentales in sacco obtenues sur des vaches fistulées. Des cibles biochimiques et histologiques ont pu être proposées pour améliorer la qualité du maïs fourrager en fonction de l'intensité du stress. Nous avons montré qu'en condition de stress sévère, bien que la production d'épis diminue significativement, la digestibilité de la MS peut être maintenue grâce à une augmentation de la digestibilité de la paroi, due à une réduction de la teneur en acides p-hydroxycinnamique, alors que la teneur en lignine reste stable comme attendu. Nous avons également montré qu'en condition de stress modéré les caractères histologiques jouent un rôle aussi important que les caractères biochimiques, mais qu'une fois qu'un seuil est atteint, seuls les caractères biochimiques modulent les variations de la digestibilité de la paroi. Une fenêtre environnementale a donc pu être mise en évidence où le rôle accru de la distribution de la lignine aux côtés des caractères biochimiques permet une augmentation du rendement digestible. Ainsi, les agriculteurs pourraient exploiter cette fenêtre pour augmenter la productivité, en régulant l'irrigation en condition de sécheresse modérée et en intégrant le SID dans un outil de gestion de l'irrigation
Maize stands as a pillar of the French forage system, with its yield and silage feeding value serving as key criteria for the registration of maize hybrid varieties in the official French catalogue. Previous research on this topic has revealed a direct correlation between silage feeding value and dry matter (DM) digestibility, which is, in turn, constrained by cell wall (CW) digestibility and significantly affected by water deficit. Studies on maize inbred lines have shown that under severe water deficit conditions, both DM and CW digestibilities increase. This increase correlates with a decrease in lignin content and changes in lignin distribution. However, it is noteworthy that breeding efforts have already fixed lignin content in hybrid varieties. Therefore, lignin content is unlikely to be a source of future digestibility improvement. To explore other CW targets and the impact of water deficit on these traits, this PhD study was conducted as part of the Carnot Plant2Pro INRAE-ARVALIS MAMMA MIA project. We grew a range of modern forage maize hybrids representative of the current S0-S1 (very-early to early flowering earliness) French market for two years under sixteen contrasted environmental conditions, including six in controlled irrigation conditions. First, we established a simple but robust stress index (SID) that considers the water deficit in the soil and the air temperature. This SID provided a key environmental ranking tool, highlighting severe stress due to high temperature that significantly impacted DM digestibility compared to moderate stress conditions. Secondly, to encompass a wide range of environmental conditions in biochemical quantifications, we developed several predictive near-infrared spectroscopy (NIRS) equations capable of robustly and accurately predicting fine cell wall traits and relationships, mirroring levels observed in laboratory experiments. While these equations prove sufficiently robust for use in selection programs, we emphasize the need for vigilance in accurately estimating prediction accuracy under stress conditions, particularly in equations applied to hybrid material where trait variation ranges are often limited. The core dataset of this work enabled a multiscale analysis, integrating agroclimatic, agronomic, biochemical, and histological traits, along with in sacco experimental data on cows. We proposed biochemical and histological traits to improve the quality of forage maize depending on stress intensity. We demonstrated that under severe stress, ear production decreases significantly, but DM digestibility can be maintained by increasing CW digestibility. This boost in CW digestibility was due to a reduction in p-hydroxycinnamic acid content, while lignin content remained stable, as anticipated. The significance of lignin distribution increased with the severity of stress, reaching an extreme threshold where biochemical parameters solely account for digestibility variations. This two-threshold model presents a window of opportunity located at the first threshold between non-stressed and moderately stressed environments, where the increased role of lignin distribution alongside biochemical traits enabled an increase in digestible yield. By controlling irrigation doses in the field under moderate drought conditions and integrating the SID into an irrigation management tool, farmers could exploit this window to increase productivity

Three experiments were carried out to determine i) the quantity and composition of maize forage harvested at different stages of growth, ii) the effect on the milk yield of dairy cows fed on maize forage silages harvested at two stages of maturity together with two levels of dairy concentrate, iii) the effect of supplementing early and late cut silages with either dairy concentrate or cottonseed cake on dry matter intake and milk yield of dairy cows. Forage dry matter yield showed a small non-significant increase with advancing maturity. The contents of dry matter, ash, acid detergent fibre and lignin increased significantly with crop maturity. Crude protein content and dry matter degradability declined significantly as the crop matured. Grain and stover production were significantly reduced by early defoliation. The effects of stage of maturity on the composition of forage and the yields of grain and stover were smaller in the last three stages of defoliation. The effect of type of silage on dry matter intake was inconsistent in the three feeding trials. Dairy cows consumed similar amounts of either early or late cut maize silage in the first year. In the second trial, cows that were fed on early silage ate significantly higher amounts of silage dry matter than those fed on late silage. In the third year the opposite trend was observed. Within each silage, level and type of concentrate offered to the animals had no influence on silage intake. There were no substitution effects in the two feeding trials when different amounts of concentrate were fed with the silages. Milk production from cows that were fed on early silage was about 10% higher than that of cows fed on late silage. This difference was significant in two years. The higher level of concentrate supplementation gave 9% more milk than the lower level. Feeding the silages with dairy concentrate rather than cottonseed cake gave more milk per cow per day. There were no interactions between silage and concentrate effects on milk yield. Milk production when cows were grazing followed similar trends to those recorded in the silage feeding periods. The cows that were supplemented with four kg of concentrate partitioned more energy towards body weight gain than those fed on two kg of concentrate. Efficiency of utilisation of energy for milk production was lower when cows received four rather than two kg of concentrate. Metabolisable energy in early silage was better utilised for milk production than that in late silage. Feeding the two silages with cottonseed cake improved efficiency of energy utilisation for milk production.

Kenntnisse zur Blattflächenentwicklung von Silomaissorten während der Vegetationsperiode sind erforderlich, um die Ausreife der Pflanzen charakterisieren und neue Sorte bewerten zu können. Die Blattfläche ist eine Funktion von Blattzahl und Blattfläche und kann den Ertrag und die Futterqualität von Silomais in Abhängigkeit von den Umweltbedingungen in unterschiedlichem Ausmaß variieren. Ein maßgebliches Kriterium für das Erreichen einer guten Futterqualität ist die Prognose des optimalen Erntetermins. In den Jahren 2002 und 2003 wurden zwei Experimente am Standort Berge des Institutes für Pflanzenbauwissenschaften (Landwirtschaftlich-Gärtnerische Fakultät der Humboldt-Universität zu Berlin) durchgeführt, um zu zeigen, wie sich Silomaissorten der Reifegruppen früh und mittelfrüh im Blattflächenindex, in der Blattentwicklung sowie spezifischen Blattfläche unterscheiden und welche Unterschiede zwischen zwei Messmethoden zur Bestimmung des Blattflächenindexes bestehen. Unter Beachtung von Ertrag und Futterqualität haben sich bei limitiertem Wasserangebot unter den gegebenen Standortbedingungen Sorten mit einer geringeren Anzahl von Blattgenerationen (13 bis 16) als geeignet erwiesen. Um Trockenmassegehalte in der Gesamtpflanze im optimalen Bereich von 30 bis 35 % im Erntegut garantieren zu können, sollte Silomais speziell unter trocken-heißen Abreifebedingungen dann geerntet werden, wenn mindestens zwei Blätter unterhalb des Kolbenansatzes noch grün sind.
Knowledge of leaf area development of silage maize varieties during the vegetation period is useful in the characterisation of the maturity conditions of plants and in the evaluation of new varieties. Leaf area, which is a function of leaf number and leaf size may affect yield and quality parameters of silage maize at varying levels, depending on the environmental conditions under which the crops are grown. One of the criteria for obtaining good quality forage is prognosis for optimum harvest time. Two experiments were conducted in 2002 and 2003 at Berge research station, belonging to the Institute of Crop Science (Faculty of Agriculture and Horticulture, Humboldt-University Berlin) with the aim to assess how silage maize varieties of maturity group early and mid early differ in LAI, leaf area development, specific leaf area, what differences exist between the two methods used to measure LAI. Considering yield and forage quality, under the condition of location Berge, with limited water availability, varieties with fewer leaves (13-16) may be suitable. To maintain the whole plant dry matter content within the optimum range (30-35%), especially under drought condition, harvest time must fall within the period when at least a minimum of two leaves below the cob leaf are still green.

In intensive beef cattle production feeding plans are based on Total Mixed Ration (TMR) rich in concentrate feedstuff to promote high daily gain and a limited portion of fibrous ingredients is included to promote rumination. In these type of diets, the requirement of fiber is fulfilled by roughages such as straw or hay while farmers do not consider maize silage (MS) as a possible alternative. The suitability of MS for beef cattle nutrition is amply recognized, however the present project was developed through different approaches to support the thesis of the use of MS as sole forage source in beef cattle diets. The project started with a survey on a conspicuous sample of intensive Italian beef cattle farms, placed in an area in which most of the farming activities involve cereals and in particular maize. The data collected were about the current use of MS, the characteristics of its utilization, the quality of the product and the diets in which the silage is included. A sample of 406 commercial beef cattle farms located in the Po Valley were selected in order to cover the most diverse rearing situations, in terms of farm size and cattle genotype, in which MS was fed to beef cattle during the finishing period. Each farm was visited to collect information about the feeding regimen and representative samples of TMR and MS were collected for chemical and physical analysis. Regardless of chop length, the quality of MS population was satisfactory both by a nutritional and a preservation standpoint, as indicated by principal chemical parameters and fermentation profile. A physical analysis of MS samples showed a wide range of particle size, as result of the different chopping lengths during harvest. On average, MS content in diets accounted for 8 kg of fresh weight or 33.4% to the total dietary dry matter (DM) but a large standard deviation (11.4%) was observed across farms. The decision about the amount of MS to be included in the TMR has shown to be independent on both chemical composition and particle size of the roughage. In diets with a high quantity of MS the risk of occurrence of rumen acidosis due to the additional starch brought by this silage resulted balanced either by a significant reduction in the amount of other starch sources or by the higher fiber content and the coarser size of the dietary particles which should promote a prolonged rumination. A method of estimation of risk for forage damages during diet preparation was applied and results showed that in more than 30% of the farms MS was damaged during this phase with a loss of long particles. A logistic analysis demonstrated that the relative risk of MS damage was significantly increased either by a larger inclusion of the roughage in the TMR or by the use of silage with coarser particles. From the outputs of the survey, a study was made to verify if different levels of inclusion of MS in diets fed to finishing bulls had any effects on their carcass traits and meat quality. The top level of inclusion of the forage in diets could be considered high as compared to the averages registered in the first survey, and this helped to verify in specific any negative effect of pushing on the quantity of the silage in diets. A further interesting aspect of this study was the fact that animals tested were reared in beef farms on common market conditions, without interventions by researchers on diets or farm managing. A sample of 6 intensive beef farms was selected according to the feeding plan adopted during the fattening period of Charolais bulls. Two farms did not include any MS in the diet (MS0), while MS represented 22% of the dietary DM in the second group of 2 farms (MS22), and it raised up to 44% of the dietary DM in the last 2 farms (MS44). Five bulls were randomly selected from each farm to be slaughtered at a standard commercial finishing condition in the same abattoir. Carcass quality evaluation as well as meat physical characteristics and chemical analysis showed no variations due to the different silage inclusion in the diet. Since few parameters were slightly influenced by the difference in diets composition, therefore, based on these findings, there were no substantial arguments against the use of a large amount of MS in the fattening diets of Charolais bulls. The subsequent experimental study was set to verify on the possibility of a conventional MS, chopped at harvest and ensiled through common market practices, was able to partially or totally substitute wheat straw (WS), the commonly used poor forage considered by operators suitable, or even essential, to prevent risks of feeding misbehaviours or onset of rumen acidosis. Four isofibrous, isocaloric and isonitrogenous diets, formulated with stepped substitution of WS with MS were fed as TMR to 4 Simmental bulls in their finishing phase according to a latin square design with periods of 28 days. The stepped substitution of WS with MS, at time of diet balancing, offered the chance to progressively reduce the need for energy concentrates increasing the forage:concentrate ratio. Dry matter intake (DMI) and bulls’ average performance were not significantly affected by the changes in the composition and the physical characteristics of diets. An effect in feeding behaviour was noticed in the fact that bulls took longer to consume the diet without silage (MS0) than any other diet while the time spent ruminating was similar across diets. Even when fed only a conventional MS as dietary roughage bulls did not seemed to try to select for the longest particles in TMR as effect of a potential symptom of acidosis. Total tract apparent digestibility was influenced by diet type: the diet with the higher content of MS showed the highest values for all digestibility parameters. Rumen fluid parameters and blood indicators of acid-base status of bulls were similar across diets and they were at all time within safety range as the risk of acidosis is concerned. The results suggested that conventional market quality MS can be used as sole roughage source in beef cattle diets, without adverse effects on performance, feeding behavior and health status of the animals. The last study was a different approach to sustain the use of MS in beef production. In this case the rearing model was the North American feedlot system, in which diets are based on a higher content of concentrates compared to those used in Central Europe. A study was carried out based on the concept of ability of cattle to express preferences in feeding behaviour. The suitability of MS was tested through the interpretation of the choices of cattle allowed to chose between ingredients offered individually or as a standard TMR. A total of 160 continental crossbred beef heifers was used in a 52-d feeding period; animals were offered 4 diet choices each one consisting on free access to 2 ingredients placed in adjacent tubs and being: TMR vs TMR (choice TMR), MS vs tempered barley grain (BG) (choice MSBG), wheat dry distillers grain (DG) vs BG (choice DGBG) and MS vs DG (choice MSDG). Performance of cattle did not differ by treatment while some differences were recorded in DMI in favour to the MSDG choice. According to results coming from analysis of feeding behaviour some differences were found especially between TMR heifers and the other animals fed other associations of ingredients: they showed higher bunk attendance durations, highest values of average meal length, higher average meal size and largest number of meals within a 24 h period. The preference was clearly shown when heifers free to choose their diets ate twice the quantity of forage than when fed the ingredients premixed; it was also shown when considering the behaviour within each association of 2 ingredients: time spent by heifers per day and per meal eating, and quantity of ingredients consumed were all different depending on feed associations. When considering the health status, in general, heifers fed TMR had the highest chance to have their rumen pH to drop to dangerous thresholds in term of subclinical acidosis while those fed MSDG seemed to be the less exposed to the risk. A trend was easily evidenced also in the case of volatile fatty acids (VFA): total VFA concentration was higher in heifers offered TMR while when considering the concentrations of individual acids a general prevalence of C2 over C3 acids was clearly shown in the rumen of heifers fed MSDG. This study submitted previous results on the ability of cattle to choose between specific feed ingredients and confirmed the suitability of MS as fiber source for high grain beef cattle diets. As a general final conclusion, the answer to the question raised at the beginning of this project about the possibility of a large use of MS in beef cattle diets is positive. The critical points of MS utilization in feeding plans for beef cattle are the managing and handling of the forage during plant harvesting, silage making and diet preparation. All these phases require attention and precision by the operators since the properties and advantages that MS can provide to the beef producer can be easily impaired by errors that can alter nutritional and physical characteristics of the forage.
Nel sistema di allevamento intensivo del bovino da carne i piani di razionamento sono basati su diete preparate con la tecnica dell’unifeed, una miscela unica ricca di alimenti concentrati per permettere alti accrescimenti e con una limitata parte di alimenti fibrosi per promuovere il comportamento naturale della ruminazione. In questo tipo di diete il fabbisogno di fibra è soddisfatto da foraggi come la paglia o il fieno di cereali mentre il silomais (SM) non è solitamente considerato dagli allevatori come possibile alternativa. Il SM è sempre stato ampiamente riconosciuto come alimento adatto alla nutrizione del bovino da carne e il presente progetto è stato sviluppato attraverso diversi approcci sperimentali a sostegno della tesi di un utilizzo di questo insilato come unico foraggio nelle razioni. Il progetto ha avuto inizio con un’indagine su un cospicuo campione di allevamenti intensivi di bovini da carne situati in un’area in cui la maggior parte delle attività agricole riguarda i cereali ed in particolare il mais. I dati raccolti riguardavano l’uso corrente del SM, le caratteristiche del suo utilizzo, la qualità del prodotto e delle diete in cui esso viene incluso. Un campione di 406 allevamenti commerciali situati nella Pianura Padana sono stati selezionati in modo da rappresentare le più diverse situazioni di dimensioni aziendali e tipi genetici in cui il SM viene fornito ai vitelloni nella fase di finissaggio. Ogni azienda è stata visitata per raccogliere informazioni sui piani di razionamento e campioni rappresentativi di unifeed e di SM sono stati raccolti al fine di sottoporli ad analisi fisica e chimica. Indipendentemente dalla lunghezza di taglio, la qualità della popolazione di SM raccolti è risultata soddisfacente sia dal punto di vista nutrizionale che da quello dello stato di conservazione, come indicato dai principali parametri chimici e del profilo fermentativo. Un’analisi della distribuzione particellare del SM ha mostrato un’ampia variabilità di dimensione delle particelle, a testimonianza delle diverse lunghezze di taglio ottenute al momento della trebbiatura. In media, il contenuto di SM nelle razioni si è attestato intorno agli 8 kg di tal quale o il 33.4% della sostanza secca (SS) totale della razione pur con un’ampia deviazione standard registrata tra allevamenti (11.4%) . La decisione sulla quantità di SM da inserire nella razione si è rivelata essere indipendente sia dalla composizione chimica che dalle caratteristiche fisiche del foraggio. In diete con alta inclusione di SM il rischio di insorgere di acidosi ruminale, dovuta all’apporto di amido portato da questo insilato è risultata bilanciata sia da una significativa riduzione dell’inclusione di alter fonti energetiche sia dal maggior contenuto fibroso e dalla maggior lunghezza di particelle che avrebbero il compito di stimolare la ruminazione. Un metodo matematico di stima del rischio della perdita di struttura del SM nelle fasi di preparazione della razione ha mostrato che in oltre il 30% degli allevamenti l’insilato ha subito tale danno con la conseguente riduzione del contenuto di particelle lunghe. L’analisi logistica ha poi dimostrato che il rischio relativo del danno era accresciuto sia da una maggior inclusione dell’insilato nella razione che dall’utilizzo di SM con maggior contenuto di particelle lunghe. Partendo dai risultati dell’indagine, un successivo studio ha verificato se diversi livelli d’inclusione di SM nelle razioni di vitelloni in finissaggio potesse avere effetti sulle caratteristiche qualitative della carcassa e della carne. Il livello massimo di inclusione del foraggio nelle razioni poteva essere considerato alto, alla luce dei dati registrati nella precedente indagine, e questo ha permesso di verificare nello specifico l’esistenza di effetti negativi in risposta ad una eventuale spinta sulla quantità di SM nelle razioni. Un ulteriore aspetto interessante dello studio è stato il fatto che gli animali presi a campione erano allevati in condizioni normali di mercato, senza interventi dei ricercatori sulle diete o sulla gestione delle pratiche aziendali. Un campione di 6 allevamenti di bovini da carne è stato selezionato in base ai piani di razionamento applicati durante la fase di finissaggio di vitelloni Charolais. Due aziende non facevano uso di SM, due ne utilizzavano il 22% e due il 44% della SS totale della razione. Cinque vitelloni sono stati presi a random da ogni allevamento e sono stati macellati a maturazione commerciale nello stesso macello. Le caratteristiche della carcassa, come le qualità organolettiche e l’analisi chimica della carne non hanno mostrato variazioni dovute al diverso quantitativo di SM nelle razioni. Dato che pochi parametri sono stati lievemente influenzati dalle differenze delle razioni, non sono state trovate prove a discapito dell’utilizzo di alte quantità di SM nelle razioni per vitelloni Charolais. Il successivo studio è stato predisposto per verificare la possibilità che un SM convenzionale, tagliato in campo e insilato tramite normali pratiche comuni nel settore dell’allevamento, fosse in grado di sostituire parzialmente o totalmente la paglia di frumento, ovvero il foraggio di bassa qualità la cui presenza è considerata irrinunciabile dagli allevatori per prevenire i problemi di acidosi ruminale. Quattro diete bilanciate per il contenuto di fibra, energia e proteina, formulate con progressive sostituzione di paglia con SM, sono state fornite a quattro vitelloni Simmental in fase di finissaggio seguendo lo schema sperimentale del quadrato latino con periodi di 28 giorni. Fin dal momento della formulazione delle razioni l’aumento del SM nella razione a danno del contenuto di paglia ha dimostrato il vantaggio di poter ridurre progressivamente anche l’apporto di alimenti concentrati grazie alle caratteristiche di questo insilato di apportare fibra ma anche un discreto contenuto di amido. Il consumo di SS e le performance medie dei vitelloni non sono state significativamente influenzate dalle suddette differenze di razionamento. È stato invece riscontrato un effetto nel comportamento alimentare degli animali nel fatto che essi hanno impiegato maggior tempo a consumare la razione senza SM a cui non ha corrisposto un aumento del tempo speso a ruminare la stessa razione. Anche quando alimentati con un SM di tipo convenzionale rispetto alle condizioni di mercato i vitelloni non hanno dimostrato necessità di selezionare le particelle più lunghe della razione come ad evitare di cadere in situazione di acidosi ruminale. La sostituzione tra foraggi ha influenzato la digeribilità totale apparente delle razioni: la formulazione con il maggior contenuto di SM ha fatto registrare i più alti valori per tutti i parametri di digeribilità. I parametri relativi all’ambiente ruminale e gli indicatori sanguigni dell’equilibrio acido-base sono risultati simili nei vitelloni alimentati con le diverse razioni e allo stesso tempo erano entro margini di sicurezza per quanto riguarda il rischio di acidosi. I risultati hanno suggerito che un SM di tipo convenzionale rispetto alle condizioni di mercato ha le caratteristiche adatte all’utilizzo come unico foraggio nelle razioni per bovino da carne, senza generare effetti negativi a livello fisiologico e produttivo. L’ultimo studio ha rappresentato un approccio diverso a sostegno dell’utilizzo del SM nella produzione del vitellone da carne. In questo caso il modello produttivo era quello dei grandi allevamenti del Nord America, nei quali i piani di razionamento sono basati su contenuti di alimenti energetici maggiori rispetto a quelli comuni in Europa Centrale. Lo studio è stato svolto nell’ambito delle comprovate teorie sulla capacità dei bovini di esprimere preferenze alimentari. L’idoneità dell’uso del SM nelle razioni per bovini all’ingrasso è stata testata attraverso l’interpretazione delle preferenze di animali a cui è stata offerta libertà di scelta tra alimenti offerti singolarmente o mescolati in un unifeed standard per le condizioni produttive locali. Un gruppo di 160 manze di incroci di razze da carne inglesi è stato utilizzato in uno studio della durata di 52 giorni: agli animali sono state offerte 4 alternative ognuna consistente nel libero accesso a 2 alimenti posti individualmente in mangiatoie adiacenti. Le associazioni erano unifeed vs unifeed, (scelta unifeed), SM vs granella schiacciata d’orzo (GO)(scelta SMGO), distillers secchi di frumento (DF) vs GO (scelta DFGO) e SM vs DF (scelta SMDF). Le performance dei bovini non sono variate mentre alcune differenze sono state registrate nel consumo di SS di SMDF. Dai risultati dell’interpretazione del comportamento alimentare sono state trovate alcune differenze specialmente tra le manze alimentate con la scelta unifeed e gli altri gruppi: le prime hanno mostrato maggiori tempi di presenza alla mangiatoia, maggiori valori di lunghezza media dei pasti e maggior numero di pasti durante un periodo di 24h. La preferenza è stata chiaramente manifestata nei confronti di alcune associazioni di alimenti, ad esempio nel caso in cui le manze potendo scegliere hanno consumato il doppio del foraggio rispetto a quando avevano a disposizione una razione con foraggi e concentrati mescolati tra loro; un altro evidente esempio è venuto dal comportamento nel caso di ogni associazione di alimenti: il tempo speso dagli animali in un giorno, la durata del pasto e la quantità di ingredienti assunta sono risultate spesso diversi a seconda delle diverse alternative offerte. A livello di stato di salute, in generale le manze che accedevano alla scelta unifeed hanno mostrato la più alta tendenza all’avvicinarsi del loro pH ruminale a soglie di rischio per l’insorgere di acidosi subclinica mentre gli animali del gruppo MSDG sono apparsi quelli meno esposti al rischio. Anche nel caso degli acidi grassi volatili è risultato esserci un legame con il tipo di scelta alimentare: la concentrazione degli acidi totali è risultata più alta nelle manze del gruppo unifeed mentre a livello di singoli acidi si è verificata una generale prevalenza dei composti C2 su quelli C3 a livello del rumine degli animali della scelta MSDG. Questo studio ha convalidato i precedenti risultati riguardo la capacità dei bovini di manifestare preferenze nei confronti di alimenti specifici ed ha confermato i risultati positivi ottenibili dall’utilizzo del SM come foraggio nelle diete per bovini da carne ad alto contenuto di concentrati. Come conclusione generale si ritiene di poter rispondere positivamente al quesito posto a inizio progetto riguardo la fattibilità di utilizzo di alte quantità di SM nelle razioni per bovini da carne. I punti critici di questo impiego dell’insilato sono individuabili nella gestione del foraggio durante le fasi di taglio in campo della pianta, della preparazione della trincea e della preparazione della razione. Tutte queste operazioni richiedono particolare attenzione e precisione da parte degli operatori dato che le proprietà ed i vantaggi che il SM può offrire agli allevatori di bovini da carne possono essere facilmente compromessi da errori che possono alterare le caratteristiche nutrizionali e fisiche dell’insilato.

L’ensilage de maïs, fourrage principal dans les rations hivernales des ruminants à haut niveau de production, est composé de deux fractions énergétiques : l’amidon et les parois végétales. Les proportions relatives de ces deux fractions varient selon le stade de maturité de la plante à la récolte, la variété cultivée et les conditions de culture. Proposé dans les années 1990, le système de prévision de la valeur nutritive de l’ensilage de maïs, basé sur l’estimation de la digestibilité de la matière organique (dMO) dans le tube digestif total, nécessite d’être amélioré pour prendre en compte de façon explicite la contribution respective de l’amidon et des parois végétales à la MO digérée, et permettre d’estimer la part de l’amidon dégradée dans le rumen. Par ailleurs, la validité des équations actuellement utilisées doit être vérifiée sur les nouvelles variétés de maïs et pour des pratiques de récolte qui ont sensiblement évolué par rapport aux années 1980. Les objectifs de la thèse étaient 1) d’acquérir de nouvelles données de référence de la dMO et des fractions amidon et parois végétales de l’ensilage de maïs mesurées in vivo, 2) de préciser la partition de la digestion de l’amidon et des parois végétales entre le rumen et les intestins et 3) de rechercher de nouveaux critères de prévision du devenir de l’amidon et des parois végétales dans le tube digestif. La digestibilité in vivo chez le mouton a été mesurée pour 36 ensilages de maïs résultant pour 32 d’entre eux de la culture 2 années consécutives en un même site de 4 variétés récoltées à 4 stades de maturité ; 4 ensilages supplémentaires ont été réalisées sur un second site de culture avec 2 variétés et 2 stades de maturité. La dégradabilité ruminale in sacco de l’amidon et des parois a également été mesurée chez la vache pour ces 36 maïs avec une méthodologie mise au point pour les fourrages riches en amidon. Pour les 4 ensilages de maïs cultivés sur le second site, un bilan digestif complet au niveau du rumen et des intestins a été réalisé sur vaches. Par rapport aux données des Tables INRA 2007 issues des mesures réalisées sur le maïs en vert à la fin des années 1980, les maïs utilisés dans cette thèse se caractérisent par une teneur en amidon plus élevée, une teneur en parois végétales plus faible, une dMO comparable, mais une digestibilité des parois végétales plus faible. La relative stabilité de la dMO avec le stade de maturité à la récolte s’explique par un phénomène de compensation entre l’augmentation de la quantité d’amidon digestible et la diminution de la quantité de parois digestibles. Le type de variété et le stade de maturité à la récolte influencent la partition de la digestion avec une dégradabilité ruminale de l’amidon plus faible pour les stades de récolte tardifs, ce qui induit des profils fermentaires différents. Bien que la composition chimique des maïs ait évolué, l’équation de prévision de la dMO proposée par l’INRA en 1996, à partir de la digestibilité pepsine-cellulase mesurée au laboratoire, a pu être validée sur les données in vivo et reste pertinente pour prévoir la dMO en pratique. Les nouvelles données de référence acquises sur animaux qui ont été mises en relation avec des critères chimiques et enzymatiques mesurés au laboratoire et avec des critères agronomiques seront utilisées pour mieux caractériser la valeur nutritive des maïs fourrage dans SYSTALI, le nouveau système d’alimentation proposé par l’INRA
Maize silage, commonly used in the diet of high-yielding ruminants, provides two energetic fractions: starch and cell wall (NDF). The proportion of the two energetic fractions in the whole plant varies with the stage ofmaturity at harvest, type of hybrid and climatic conditions. The prediction system of maize silage’s nutritive value developed in the 1990s, is based on the estimation of in vivo total tract organic matter digestibility (Omd). This system needs to be revised to better take into account the respective contribution of starch and cell wall in the digested organic matter and therefore to allow the prediction of the starch degradation in the rumen. Moreover, validity of prediction equations requires to be tested with current hybrids of maize and harvest practices which changed compared to 1980s. The aims of the thesis were to 1) obtain new references on Omd and on in vivo digestibility of starch and cell wall, 2) specify partition of starch and cell wall digestion between rumen and intestines, 3) investigate new prediction criteria of starch and cell wall digestion. In vivo digestibility in sheep was measured on 36 maize silages. Thirty-two maize silages were obtained from 4 hybrids that were cultivated for 2 consecutive years in the same location and harvested at 4 stages of maturity. Four additional silages (2 hybrids and 2 maturity stages) were produced in different location. In sacco starch and cell wall degradability in the rumen was measured in cows for the 36 maize silages with an adapted methodology developed in this thesis for high starch content forages. For the 4 maize silages harvested in the second location, the digestion in the rumen and in the intestines was quantified in vivo on cows. Maize silages of this thesis were characterized by higher starch content, lower cell wall content, similar OMd but lower in vivo digestibility of cell walls compared to INRA 2007 data, obtained from measures on fresh plant in 1980s. The relative stability of OMd with stage of maturity was explained by the compensation between the increase in the content of digestible starch and the decrease in digestible cell wall content. Type of hybrid and maturity stage at harvest affected digestive partition with lower starch degradability in the rumen for late maturity stages involving differences in fermentation profiles in the rumen. Although chemical composition of maize has changed, the INRA equation used to predict OMd from laboratory pepsin-cellulase digestibility has been validated on the in vivo data of the thesis and, therefore remains relevant for OMd prediction. New in vivo datas, in relation to chemical, enzymatic and agronomy parameters, will allow better evaluation of the nutritive value of maize silage in the future feed evaluation systems developed by INRA

162 leaves printed on single pages, preliminary pages i- vii and numbered pages 1-152. Includes bibliography and abbreviations.
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Thesis (PhD(Agric))--University of Stellenbosch, 2000.
ENGLISH ABSTRACT: Maize, forage sorghum, lucerne, oats, barley and triticale are the most common silage crops in South Africa, while tropical grasses like Eragrostis curvula and Digitaria eriantha are ensiled to a lesser extent. The aim of this study was to determine the effect of adding a lactic acid bacterial inoculant to E. curvula, D. eriantha, lucerne, forage sorghum, maize and oat silage. The effect of the addition of a lactic acid bacterial inoculant when ensiling E. curvula on the fermentation dynamics during ensiling and the aerobic stability of the silage was determined. The addition of the lactic acid bacterial inoculant to E. curvula at ensiling resulted in a more rapid lowering in pH and improved preservation. Inoculated silage had a higher lactic acid content, less protein breakdown and a lower butyric acid content compared to that of the control silage. Both silages were stable when exposed to air for five days. Digitaria eriantha was ensiled, with or without the addition of a lactic acid bacterial inoculant containing Lactobacillus plantarum. Streptococcus faecium and Pediococcus acidilactici together with the enzymes, cellulase, hemicellulase and amylase. The addition of the inoculant resulted in a more rapid drop in pH, a higher level of lactic acid, an increase in the number of lactic acid bacteria, less protein breakdown and lower numbers of enterobacteria, clostridial spores, yeast and mould compared to the control silage. Digitaria eriantha hay, control and inoculated silage diets were fed to 24 Merino rams (n = 8 per treatment) to determine intake and digestibility. The intake of diets consisting of 90.9% D. eriantha hay, control silage or inoculated silage, differed significantly (p<0.05) at 1395, 1540 and 1848 g DM/day, respectively. The in vivo organic matter digestibility (glkg) of D. eriantha hay, untreated silage and inoculated silage diets was 561, 546, 574, respectively. The addition of the bacterial inoculant when ensiling D.eriantha resulted in better preservation, improved aerobic stability, as well as a higher in vivo organic matter digestibility and intake of D. eriantha silage. The addition of an inoculant or molasses to lucerne (Medicago sativa), ensiled in laboratory silos was investigated. The addition of the additives resulted in an increased preservation rate as indicated by a more rapid lowering of pH, a faster rate of lactic acid production and less protein breakdown compared to control silage. The inoculant was more effective than the molasses in improving the rate of preservation. The aerobic stability of lucerne silage was not affected by inoculation or the addition of molasses. The addition of an inoculant to wilted big bale lucerne silage was studied. The inoculant improved silage quality as indicated by a lower pH, higher lactic acid content, lower ammonia nitrogen content and lower level of butyric acid in inoculated silage compared to the control lucerne silage. The composition of big round bale lucerne silage differed markedly from that of lucerne ensiled in laboratory silos as the former had a higher pH, ammonia nitrogen, butyric acid and acetic acid content and a lower lactic content. Whole crop forage sorghum cultivar FS2 was harvested at the late bloom (20.7% DM) and soft dough (28.9% DM) stages of maturity and ensiled in laboratory silos with the addition of commercial silage inoculants. At both stages of maturity the inoculants caused a more rapid rate of pH decline and a higher amount of lactic acid production. All the silages were well preserved. Silages of the sorghum ensiled at the late bloom stage with all treatments were stable after 5 days of aerobic exposure, whereas sorghum ensiled at the soft dough stage with the addition of the inoculants deteriorated upon aerobic exposure. It is concluded that addition of lactic acid bacterial inoculants to mature sorghum at ensiling might impair the aerobic stability of the silage. The yield, nutritional value and production potential of silage made from twenty one maize hybrids was compared. It was concluded that maize hybrids did differ in metabolizable energy content, rate of digestion, predicted intake and predicted milk production potential. The content of NDF and ADF did not differ between the maize hybrids used in this study and could therefore not be used to predict nutritional value or production potential. Maize was harvested at the hard dough stage and ensiled with or without the addition of a lactic acid bacterial inoculant in laboratory silos and in 210 litre drums. The adding of the inoculant to maize at ensiling did not result in a more rapid drop in pH and higher levels of lactic acid. The intake and growth of South African Mutton Merino lambs fed inoculated and untreated maize silage diets was determined. The average daily gain of lambs fed a diet consisting of either 60% control or inoculated maize silage over a growth period of 60 days was 239 ± 26 and 255 ± 44 g/day, respectively. Although the laboratory study showed very little effect of adding a lactic acid bacterial inoculant to maize at ensiling, lambs tended to consume more of the inoculated silage. In the second study the effect of the addition of a lactic acid bacterial inoculant with an enzyme to maize at ensiling on the fermentation dynamics during ensiling, aerobic stability of the silage, the intake, milk production and milk composition of Jersey cows fed maize silage diets was determined. The inoculant did not result in a more rapid lowering of the pH or a more rapid lactic acid production compared to untreated maize silage made in laboratory silos. Both the control and inoculated maize silages were well preserved. The addition of the inoculant to maize at ensiling improved the palatability, intake and the aerobic stability of maize silage compared to the untreated control maize silage. Milk production, milk composition, live weight and condition score of Jersey cows was not significantly affected by the addition of the inoculant to maize silage. The effect of the addition of an enzyme containing lactic acid bacterial inoculant to big bale oat (Avena sativa, cv Cederberg) silage on silage composition, silage intake, milk production and milk composition of Jersey cows was determined. The crop was cut at the bloom stage, wilted and ensiled in big round bales. The inoculant, Sil-All, was applied during the baling process on half of the bales. Silages were fed to Jersey cows in an intake and milk production study. Both the control and inoculated oat silages were well preserved. The inoculated oat silage had a lower level of butyric acid than the control oat silage. Cows fed the inoculated oat silage produced more (P=O.05) milk (17.7 kg/day) than cows fed the control oat silage (16.7 kg/day). The addition of a lactic acid bacterial inoculant to big bale oat silage improved silage composition and animal performance. This study clearly showed that the composition of silages made in bunker silos under commercial farm conditions differ largely from that of silages made in small scale laboratory silos. When the effect of silage additives on aerobic stability of silage is determined the evaluation should include studies on large scale bunker silages. Evaluation of silage additives should include intake and animal production studies.
AFRIKAANSE OPSOMMING: Mielies, voersorghum, lusem, hawer, gars en korog word algemeen as kuilvoer gewasse benut terwyl tropiese grasse soos Eragrostis curvula en Digitaria eriantha tot 'n mindere mate ingekuil word. Die doel van hierdie studie was om die invloed van 'n melksuurbakterieseinokulant op E. curvula-, D. eriantha-, lusem-, voersorghum-, mielie- en hawerkuilvoer te bepaal. Die invloed van 'n melksuurbakteriese-inokulant op die fermentasiedinamika en die aerobiese stabiliteit van E. curvula-kuilvoer is bepaal. Die toediening van die melksuurbakterieseinokulant tot E. curvula tydens inkuiling het 'n vinniger tempo van pH daling en beter preservering tot gevolg gehad in vergelyking met kontrole kuilvoer. Inokulant behandelde kuilvoer het 'n hoer melksuurinhoud, minder protei'en afbraak en 'n laer bottersuurinhoud as kontrole kuilvoer gehad. Beide kuilvoere was stabiel tydens blootstelling aan lug vir vyf dae. Digitaria eriantha is ingekuil met ofsonder die toediening van 'n melksuurbakteriese-inokulant wat Lactobacillus plantarum. Streptococcus faecium en Pediococcus acidilactici sowel as die ensieme, sellulase, hemisellulase and amilase bevat het. Die inokulant het 'n vinniger tempo van pH-daling, hoer vlakke van melksuur en melksuurbakterie, minder protei'en afbraak en laer getalle van enterobakterie, klostridiale spore, giste and swamme in vergelyking met die kontrole tot gevolg gehad. Digitaria eriantha hooi, kontrole kuilvoer en gei'nokuleerde kuilvoer diete is aan 24 Merino ramme (n = 8 per behandeling) gevoer vir bepaling van inname en verteerbaarheid. Die inname van diete wat uit 90.9% D. eriantha hooi, kontrole kuilvoer of gei'nokuleerde kuilvoer bestaan het, het betekenisvol (p<0.05) verskil en was 1395, 1540 en 1848 gDM/dag, respektiewelik. Die in vivo organiesemateriaal verteerbaarheid (gIkg) vanD. eriantha hooi, kontrole kuilvoer en geYnokuleerde kuilvoer was 561, 546, 574, respektiewelik. Die toediening van die bakteriese-inokulant tydens inkuiling vanD. eriantha het beter preservering, verbeterde aerobiese stabiliteit asook 'n hoer in vivo organiesemateriaal verteerbaarheid van D. eriantha kuilvoer tot gevolg gehad. Die effek van toediening van 'n melksuurbakteriese-inokulant en van molasse tot lusem (Medicago sativa) ingekuil in laboratoriumsilos is ondersoek. Die inokulant toediening en molasse toediening het die tempo van preservering versnel, die pH het vinniger gedaal, melksuur is teen 'n hoer tempo geproduseer en minder proteYen afbraak het plaasgevind in vergelyking met die kontrole kuilvoer. Die tempo van preservering is meer effektief deur toediening van die inokulant verhoog as deur die toediening van molasse. Die aerobiese stabiliteit van lusernkuilvoer is nie beYnvloed deur die toediening van inokulant ofmolasse nie. Die effek van die toediening van 'n melksuurbakteriese-inokulant tot groot rondebaal lusernkuilvoer is ondersoek. Die inokulant het die kwaliteit van die kuilvoer verbeter en het 'n laer pH, hoer melksuur, laer ammoniak stikstofen laer bottersuurinhoud in rondebaallusernkuilvoer tot gevolg gehad in vergelyking met kontrole kuilvoer. Groot rondebaallusernkuilvoer het grootliks verskil van lusernkuilvoer wat in laboratoriumsilos ingekuil is. Die rondebaal kuilvoer het 'n hoer pH, hoer ammoniak-stikstof-, bottersuur- en asynsuurinhoud en 'n laer melksuurinhoud gehad as laboratorium lusernkuilvoer. Voersorghum kultivar FS2 is op die laat blom (20.7% DM) en op die sagte deeg (28.9% DM) stadium met die byvoeging van melksuurbakteriese-inokulante ingekuil in laboratoriumsilos. Toediening van beide inokulante tot sorghum hetop beide die inkuilstadiums gelei tot 'n vinniger tempo van pHdaling en meer melksuurproduksie. Aile kuilvoere insluitend die kontrole kuilvoer was goed gepreserveer. Kontrole sowel geYnokuleerde sorghumkuilvoer ingekuil op die laat blomstadium was stabiel tydens aerobiese blootstelling vir 5 dae. Sorghumkuilvoer ingekuil op die sagtedeegstadium met die byvoeging van inokulante was onstabiel tydens aerobiese blootstelling. Die toediening van melksuurbakteriese-inokulante tot sorghum wat op die sagtedeegstadium ingekuil word kan aerobiese stabiliteit van die kuilvoer grootliks benadeel. Die opbrengs, voedingswaarde en produksiepotensiaal van kuilvoer gemaak van 21 mielie hibriede is vergelyk. Verskille in metaboliseerbare energie inhoud, tempo van vertering, voorspelde inname en voorspelde melkproduksie het tussen mielie hibriede voorgekom. Die neutraalbestandevesel- en suurbestandeveselinhoud het nie verskil tussen hibriede nie en derhalwe kon dit nie gebruik word om voedingswaarde ofproduksiepotensiaal te beraam rue. Mielies is op die hardedeegstadium met of sonder die toediening van 'n melksuurbakterieseinokulant in laboratoriumsilos en 210 liter dromme ingekui!. Die toediening van die inokulant het geen invloed op tempo van pH-daling ofproduksie van melksuur gehad nie. Die inname en groei van SA Vleismerino lammers wat 'n dieet bestaande uit 60% kontrole of inokulant behandelde mieliekuilvoer ontvang het, is bepaa!. Die gemiddelde daaglikse toename van lammers was 239 ± 26 and 255 ± 44 g/dag vir die kontrole en inokulant mieliekuilvoer dieet respektiewelik. Alhoewel die laboratoriumstudie weinig verskille tussen die kontrole en die geYnokuleerde mieliekuilvoer getoon het, het lammers geneig om meer van die geYnokuleerde mieliekuilvoer in te neem. In die tweede studie met mieliekuilvoer is die effek van toediening van 'n melksuurbakteriese-inokulant met ensieme, op die ferrnentasiedinamika tydens inkuiling, die aerobiese stabiliteit van mieliekuilvoer asook die inname, melkproduksie en melksamestelling van Jersey koeie bepaa!. Die inokulant het nie die tempo van pH daling en produksie van melksuurverhoog nie en beide kontrole en geYnokuleerde mieliekuilvoerwas goed gepreserveer. Die toediening van die inokulant tot mieliekuilvoer het die smaaklikheid, inname en die aerobiese stabiliteit van mieliekuilvoer verhoog in vergeiyking met kontrole mieliekuilvoer. Melkproduksie, melksamestelling, liggaamsmassa en kondisiepunt van Jersey koeie is nie betekenisvol beYnvloed deur die toediening van die inokulant tot mieliekuilvoer nie. Die effek van die toediening van 'n ensiem bevattende melksuurbakteriese-inokulant tot groot rondebaal hawer (Avena sativa, cv Cederberg) kuilvoer op die samestelling van kuilvoer, kuilvoerinname, melkproduksie en melksamestelling van Jersey koeie is bepaa!. Die gewas is gesny op die blomstadium, verwelk en as rondebaalkuilvoer gepreserveer. Die inokulant, Sil-All, is tydens die baalproses toegedien op die helfte van die bale. Kuilvoere is aan Jersey koeie gevoer in 'n inname en melkproduksiestudie. Beide die kontrole en geYnokuleerde hawerkuilvoer was goed gepreserveer. Die bottersuurinhoud van geYnokuleerde hawerkuilvoer was laer as die van die kontrole hawerkuilvoer. Koeie wat geYnokuleerde hawerkuilvoer gevoer is het meer (P=0.05) melk (17.7 kg/dag) geproduseer as koeie wat kontrole hawerkuilvoer ontvang het (16.7 kg/dag). Die toediening van 'n melksuurbakteriese-inokulant het kuilvoer kwaliteit en diereproduksie verbeter. Hierdie studie wys duidelike verskille uit tussen kuilvoer wat in bunkersilos onder kommersiele toestande ingekuil is, en kuilvoer wat in laboratoriumsilos gemaak is. Wanneer die effek van kuilvoerbymiddels op die aerobiese stabiliteit van kuilvoer bepaal word behoort finale evaluasie gedoen te word op kuilvoer gemaak in bunkersilos soos onder plaastoestande plaasvind. Evaluasie van kuilvoerbymiddels behoort inname en diereproduksiestudies in te sluit.