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1
Wiryawan, I. Komang Gede. "Microbial control of lactic acidosis in grain-fed sheep." Title page, contents and summary only, 1994. http://web4.library.adelaide.edu.au/theses/09PH/09phw799.pdf.
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Bibliography: leaves 122-138. Investigates the use of microbial inoculants to prevent the onset of acidosis in acutely grain fed animals; and, the most effective combination of virginiamycin and lactic acid utilising bacteria (selenomonas ruminantium subsp. lactilytica and Megasphaera elsdenii) in controlling lactic acid accumulations in vitro.
2
Snyman, Leendert Dekker. "Qualitative characteristics of selected Atriplex nummularia (Hatfield Select)." Pretoria : [s.n.], 2006. http://upetd.up.ac.za/thesis/available/etd-04022007-162554.
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Yakub, Guliye Abdi. "Energy sources and amino acids in rumen fermentation." Thesis, University of Aberdeen, 2004. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.408786.
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In a rumen simulation technique (RUSITEC), the availability and timing of energy (maltose) supply to amino acids/peptides from thawed (frozen) grass was examined in order to determine if continuous (synchronous), rather than transient (asynchronous, with maltose infused 6 h prior to, or 6 h after feeding RUSITEC with grass), availability of energy was required for optimum ruminal fermentation. The addition and pattern of energy supply (synchronous or asynchronous) did not influence either fibre (DM) degradation or microbial numbers, although there was an indication of increased total volatile fatty acids (TVFA) and acetate production in the continuous (synchronous) maltose supply. However, the supply of energy (maltose), irrespective of the pattern of supply, improved the capture of ammonia. The effects of amino acid supplementation on mixed microorganisms fermenting a range of substrates (maize and grass silages, barley straw, avicel and xylan) that usually form part of ruminant diets were examined using gas syringe incubations. Gas production, measured at 4, 6, 8, 12 and 18 h incubation, increased by 15.6, 18.7, 18.9, 15.0 and 5.4% respectively, in the xylan substrate, suggesting xylan fermentation was stimulated by amino acids supply. This implied xylanolytic organisms within the mixed population benefited more from the amino acids. A subsequent <i>in vitro </i>(syringe) experiment was conducted to identify amino acids that may be simulatory, using a deletion approach where individual amino acids were deleted from a complete mixture of all 20 amino acids normally found in protein. Amino acid additions, either as the complete mixture or with single amino acid deletions, stimulated microbial growth and fermentation rate compared to only ammonia as the N source. Although the individual deletion of aromatic amino acids (notably tyrosine and tryptophan), as well as leucine, seemed to decrease fermentation rate, microbial yield was not affected. The mixed microbial population achieved the highest growth rate and fermentation when complete mixtures of amino acid were provided.
4
Holder, Vaughn. "The effects of specific Saccharomyces cerevisiae strains and monensin supplementation on rumen fermentation in vitro." Pretoria : [s.n.], 2008. http://upetd.up.ac.za/thesis/available/etd-08192008-131813.
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Edwards, Nicholas John. "Nitrogen assimilation by rumen microorganisms: a study of the assimilation of ammonia by rumen bacteria in vivo and in vitro." Title page, table of contents and abstract only, 1991. http://web4.library.adelaide.edu.au/theses/09PH/09phe2657.pdf.
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Carson, Mark T. "Diet, rumen fermentation pattern and butyrate metabolism in sheep." Thesis, Queen's University Belfast, 1989. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.336040.
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Karnati, Sanjay Kumar Reddy. "Application of molecular techniques to assess changes in ruminal microbial populations and protozoal generation time in cows and continuous culture." Columbus, Ohio : Ohio State University, 2006. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=osu1164662405.
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Embaby, Mohamed GalalEldeen. "EFFECTS OF UNCONVENTIONAL PLANT OILS AND RUMEN ADAPTATION ON METHANE GAS EMISSION AND RUMEN FERMENTATION CHARACTERISTICS." OpenSIUC, 2018. https://opensiuc.lib.siu.edu/theses/2353.
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The objectives of this work were to investigate the effects of unconventional oils rich in phenolic compounds and rumen adaption on methane (CH4) gas production and rumen fermentation characteristics under in vitro rumen conditions. For this purpose, two sets of trials were conducted. In the first trial, the effects of blackberry, blueberry, raspberry, pomegranate, black seed and hemp oils on CH4 production and fermentation were examined in three 24 h batch culture experiments. Treatments in each experiment consisted of control (no oil supplement), control plus corn oil, or control plus two of the unconventional oils. Oils were added to rumen cultures at 500 mg/L (equivalent to 3.3 g oil/kg of diet dry matter (DM)). After 24 h of incubation, CH4 production was not different between the control and the corn oil treatments. Of the six unconventional oils tested, only hemp and blueberry oils reduced (P<0.05) CH4 production by 9-16% relative to the control and corn oil treatments. No significant differences were observed between treatments in dry matter digestibility (DMD) or total volatile fatty acids (tVFA). Except for a reduction (P<0.05) in acetate concentration with the raspberry oil, and an increase (P<0.05) in valerate concentration with the pomegranate oil, all other treatments had similar VFA concentrations. In the second trial, the effects of adding oregano essential oil (OEO) to adapted and unadapted rumen cultures on CH4 production and rumen fermentation were evaluated under in vitro condition. Rumen cultures were obtained from continues culture fermenters fed a control diet or control diet plus OEO at 250 mg/day for 10 days. The addition of OEO decreased (P<0.05) ii CH4 production only in adapted cultures. Total VFA and acetate concentrations were greater (P<0.05) in the unadapted than adapted cultures and their concentrations decreased (P<0.05) with the addition of OEO particularly when added to the adapted cultures. Propionate concentrations were also greater (P<0.05) in the unadapted than the adapted cultures and concentrations decreased (P<0.05) with the addition of OEO. Dry matter degradability and total gas production decreased (P<0.03) with the addition of OEO in both cultures and total gas production tended (P<0.13) to be lower when added to the adapted cultures. In conclusion, our results showed that hemp and blueberry oils were moderately effective in reducing rumen CH4 formation without compromising rumen fermentation and digestibility. Oregano Essential oil addition negatively affected rumen fermentation in both adapted and unadapted cultures and the effect was greater in the adapted cultures. The greater effects of OEO on CH4 production in the adapted cultures most likely due to the lower fermentation efficiency in these cultures.
9
Zhang, Ning. "Molecular characterization of the ruminal bacterial species Selenomonas ruminantium : a thesis submitted to the University of Adelaide for the degree of Doctor of Philosophy /." Title page, contents and abstract only, 1992. http://web4.library.adelaide.edu.au/theses/09PH/09phn714.pdf.
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Thesis (Ph.D.)--University of Adelaide, Dept. of Animal Science, Waite Agricultural Research Institute, 1993.<br>Includes two of author's articles in pocket inside back cover. Includes bibliographical references (leaves 133-150).
10
Yohe, Taylor. "Performance and Development of the Rumen in Holstein Bull Calves Fed an Aspergillus oryzae Fermentation Extract." The Ohio State University, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=osu1397769968.
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Frumholtz, Pierre Paul. "Manipulation of the rumen fermentation and its effects on digestive physiology." Thesis, University of Aberdeen, 1991. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.293122.
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The aims of the present study were to determine the effects of various forms of rumen manipulation on rumen fermentation, blood metabolites and circulating gastrointestinal hormones in ruminants, and to assess any post-ruminal effects of manipulating agents. The mechanism of gut hormone release in steers fed by intragastric infusion was also examined. A long term study of defaunation in sheep indicated that a steady state was reached six months after defaunation. Whereas at the end of this period ruminal concentrations of end products of rumen fermentation and blood metabolites were similar in both faunated and defaunated animals, after only one month defaunated animals had lower rumen ammonia and blood urea concentrations than their faunated counterparts. In general the plasma concentrations of the gastrointestinal hormones gastrin and CCK remained similar between faunated and defaunated animals, although the gastrin concentration in defaunated sheep increased at one year when compared to six months after defaunation. In steers the reintroduction of protozoa increased blood glucose, which increase plasma insulin secretion. The addition of the fungal feed additive, <i>Aspergillus oryzae</i> increased the viable count of bacteria and the molar proportion of propionate in the rumen of sheep, but did not alter gut hormones or blood metabolites. The inclusion of <i>Saccharomyces cerevisiae</i> fermentation extract, monensin and their combination altered rumen fermentation and microbial populations in both sheep and bulls, but gastrointestinal hormones and blood metabolites remained unchanged. Post-ruminal infusion of yeast culture had no effect on either gastrointestinal hormones or blood metabolites. However, post-ruminal infusion of monensin increased gastrin and blood urea concentrations, suggesting a post-ruminal role of monensin in nitrogen recycling. In the current study rumen manipulations likely to affect both the supply of protein from the rumen and the end products of rumen fermentation had no significant effects on hormonal secretion. The pattern of gastrin and insulin stimulation by protein and protein breakdown products in steers fed by intragastric infusions indicated that the stimulation of these hormones by luminal contents is different in ruminants compared with monogastric animals.
12
Altaye, Belete Teferedegne. "The use of foliage from multipurpose trees to manipulate rumen fermentation." Thesis, University of Aberdeen, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.322477.
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Asiegbu, Frederick Obioma. "Fungal delignification of lignocelluloses : physiological aspects and enhancement of rumen fermentation." Thesis, University of Strathclyde, 1991. http://oleg.lib.strath.ac.uk:80/R/?func=dbin-jump-full&object_id=24262.
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This project was primarily concerned with clarifying the extent to which fungal delignification in solid substrate fermentations could be optimised and applied to enhancing the nutritional value of high-fibre lignocellulosic ruminant feeds. Ten fungi were assessed for their ability to grow on media containing cell-wall related phenolic compounds and polysaccharides. Five strains were selected as being particularly active in secreting enzymes depolymerising native insoluble crystalline celluloses and lignins. The key cell wall phenolic ferulic acid was shown to exhibit differential patterns of inhibition of saccharification of cell wall carbohydrates with differential effects on cellulose depolymerisation, endoglucanase and B-glucosidase production. Two strains were shown to secrete phenol oxidases, which were presumed to be laccases, and three produced lignin oxidases, assayed as ability to decolourise polymeric dyes in surface agar culture. Solid substrate fermentation of hay and b arley straw with lignocellulose-degrading fungi (Pleurotus sajo-caju, Chaetomium cellulolyticum and Trichoderma harzianum) gave increases in acid detergent lignin except with Coriolus versicolor or Phanerochaete chrysosporium. P. sajo-caju,C. versicolor and P. chrysosporium reduced the lignin content of spruce and birch sawdust but had no marked effect on that of rice bran. All the five fungi reduced polysaccharide contents of lignocelluloses, but depletion was not at a rate directly related to period of fermentation. Fermentations with mixed cultures of three lignolytic fungi (C. versicolor, P. sajo-caju and P. chrysosporium) led to greater reduction in lignin content than did with monocultures. Although synergistic attack was observed on total insoluble polysaccharides and hemicelluloses, this was not found with depolymerisation of celluloses. Accumulation of total solubles, both carbohydrates and phenolics, was also markedly higher with mixed than with monocultures. Five lignocelluloses were evaluated as feeds in a simulated rumen model system (RUSITEC). The lignocelluloses were supplied prior to and following fungal delignifications. Fungal pretreatment of spruce sawdust enhanced feed digestibility and daily carbon dioxide production; with untreated sawdust production of total gas and volatile acids, and bacterial population decreased with incubation in the rumen. Addition of chitin and D(+) glucosamine, major components of fungal cell walls, had no adverse effect on digestibility, production of acetate or fermentation gases except when concentrations reached >30% chitin and >1% glucosamine. The influence of cell-wall related phenolic compounds and a toxic fungal metabolite, aflatoxin, on fibre digestion and the output of rumen fermentation end products was studied. Addition of the phenolics or fungal metabolite led to varied effects on bacterial populations, volatile acid and gas (CH₄ & CO₂) evolution.
14
McMurphy, Casey Paul. "Effects of Humic/Fulvic Acid on Rumen Fermentation in Holstein Steers." Thesis, The University of Arizona, 2007. http://hdl.handle.net/10150/193335.
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Six ruminally fistulated steers (average BW 317 kg) were used in a 5 X 5 + 1 Latin Square design to determine effects of humic/fulvic acid (HFA) on serum urea nitrogen (SUN), rumen pH, rumen ammonia nitrogen (RAN), and rumen VFA production in Holstein steers. Treatments included a control (0%), 0.5, 1.0 or 1.5% HFA, and a diet containing monensin (33 mg/kg). A quadratic feed intake response was observed; with intake lowest for 0.5 and 1.0 and highest for 1.5 relative to control steers. No treatment x time interaction was observed for RAN, pH, SUN, total VFA or individual VFA. No treatment differences were observed for total VFA concentrations (mM), or for molar proportion of acetate, propionate, butyrate or valerate. A quadratic response was observed for butyrate and isovalerate. However, HFA does not alter rumen fermentation in the same mode of action as monensin.
15
Wingard, Sheryl. "EFFECT OF DIRECT-FED MICROBIALS AND MONENSIN ON IN VITRO RUMEN FERMENTATION." UKnowledge, 2014. http://uknowledge.uky.edu/animalsci_etds/42.
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The impact of supplying a mixed culture of lactate producing bacteria on in-vitro rumen fermentation of forage- (Experiment 1) and concentrate- (Experiment 2) based diets in the presence and absence of monensin was explored. In experiment 1, interactions between DFM and MON were absent (P>0.10) for gas production and fermentative end products. Gas production and fermentative end products were unaffected by DFM alone (P>0.10). Monensin decreased (P<0.001) CH4 and NH3 production, rate and total gas production, as well as total VFA concentration and molar proportions of acetate and butyrate. However, MON increased (P<0.001) proportions of propionate, valerate, isobutyrate and isovalerate. Independently, DFM and MON increased (P<0.001) end point pH. In experiment 2, DFM x MON interactions or tendencies (P=0.07, P<0.01, P<0.01) were present, DFM effects were abated by MON, for rate, total gas production and total VFA concentrations. Acetate:propionate ratio was decreased (P<0.01) with MON and was unaffected by DFM. Ammonia-N concentration was increased (P<0.01) by DFM and unaffected (P=0.75) by MON. Both DFM and MON treatment increased (P<0.01) ruminal pH levels. These studies suggest the effects of DFM and MON of in-vitro fermentation are dependent on the substrate being fermented and the observed interactions provide means for further research.
16
Yan, Tianhai. "The effects of feeding molasses on rumen fermentation, intake and milk production." Thesis, University of Glasgow, 1993. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.281907.
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Godoy, Montanez R. H. "Rumen fermentation and blood metabolites in animals fed diets based on molasses." Thesis, University of Newcastle Upon Tyne, 1986. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.372932.
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Fard, Ebrahim Rowghani Haghighi. "Chemical and nutritional characteristics of whole-crop barley ensiled at different dry matter contents with or without silage additives." Thesis, University of Newcastle Upon Tyne, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.307930.
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Loveland, Jennifer. "Hindgut fermentation in ruminating Holstein calves." Diss., Virginia Polytechnic Institute and State University, 1986. http://hdl.handle.net/10919/49826.
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The effects of quantity of dietary starch and type of dietary protein
on hindgut fermentation were evaluated. Thirty—two Holstein bull calves
were fed diets containing variable amounts of orchardgrass hay and a grain
mixture. The amount of starch and types of protein were: [L1] low starch,
soybean meal (SBM); [L2] low starch, fishmeal plus dried brewers' grains
(FBG); [Hl] high starch and SBM; [H2] high starch, FBG. The percentages
of acid detergent fiber (ADF) and crude protein were: [L1] 19.2%, 15.1%;
[L2] 18.0%, 15.6%; [H1] 9.5%, 14.9%; [H2] 9.6%, 15.4%. After calves were
fed the diets for 17 days, they were slaughtered to obtain their
intestinal tracts. Ileal, cecal, and colonic digesta and feces of calves
fed Hl and H2 versus Ll and L2 contained less water and ADF. Concentration
of nitrogen in digesta and feces did not differ. Ileal, cecal,
and colonic digesta from calves fed H1 and H2 had significantly greater
numbers of viable anaerobic bacteria and lower pH._ Cecal digesta from
calves fed high fiber diets (L1 and L2) had lower total VFA, propionate,
and buytrate concentrations than calves fed high starch diets. Colonic
and cecal digesta of calves fed diets H1 and H2 contained less ammonia.
Acetate and propionate flux across cecal epithelium ro vrtro was faster
for diets H1 and H2. Results indicate that high dietary starch stimulated anaerobic bacterial growth and fermentation in the hindgut, and enhanced
acetate and propionate flux across the cecal epithelium. Acetate and
propionate transport across the cecal wall probably is not due solely to
passive diffusion, but it may involve a carrier. Replacement of SBM by
FBG also altered cecal fermentation to a lesser extent. Calves fed H2
had significantly greater numbers of viable anaerobic bacteria in cecal
and ileal digesta and 2 to 10 times the number of bacteria associated with
“
cecal epithelium than calves fed the other diets. Butyrate cecal concentration
and production was significantly increased when calves were
fed diets containing FBG. Cecal VFA production may account for approximately
3 to 5% of digestible energy intake.<br>Ph. D.<br>incomplete_metadata
20
Brown, V. E. "An investigation of methods to predict rumen fermentation products from in vivo measurements." Thesis, Queen's University Belfast, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.368459.
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Ankrah, Peter. "Contribution of ciliate protozoa to the rumen fermentation and nutrition of the ruminant /." The Ohio State University, 1989. http://rave.ohiolink.edu/etdc/view?acc_num=osu1487598303839471.
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Cassiano, Eduardo Cuelar Orlandi. "Avaliação de anticorpos policlonais em bovinos adaptados ou não à dietas com alta proporção de carboidratos prontamente fermentescíveis após indução à acidose." Universidade de São Paulo, 2012. http://www.teses.usp.br/teses/disponiveis/10/10135/tde-17042014-100147/.
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O objetivo deste trabalho foi avaliar o efeito de um preparado de anticorpos policlonais (PAP) contra bactérias ruminais específicas, Streptococcus bovis e Fusobacterium necrophorum, em parâmetros ruminais da fermentação, em vacas canuladas, adaptadas ou não a uma dieta de alta proporção de carboidratos prontamente fermentescíveis, após indução à acidose. O delineamento experimental utilizado foi o quadrado latino 3X3 replicado em arranjo fatorial de tratamentos 3X2, sendo 2 aditivos alimentares (PAP na apresentação em pó - PAPP e PAP na apresentação líquida - PAPL) mais um grupo controle (CON) e dois manejos de adaptação à dieta, resultando em seis tratamentos. O primeiro quadrado latino foi submetido a um protocolo de adaptação à dieta do tipo gradual ou step-up: dos dias D0 a D4 os animais receberam 100% de forragem; do D5 ao D9, 30% de concentrados e do D10 ao D14, 60% de concentrados. O segundo quadrado latino recebeu 100% de forragem do D0 ao D14 (sem adaptação). Nos D15 e D16, todos os animais receberam dieta com 80% de concentrados. Para as análises foram coletadas amostras de líquido ruminal a cada 3 horas a partir da 0h antes da alimentação até as 36h (D15 e D16) durante o desafio com uma dieta de 80% de concentrados. Os dados foram analisados pelo procedimento Mixed do SAS com nível de significância de 0,05. Foi observada interação entre tempo e adaptação (P<0,05) para pH ruminal com diferença entre método de adaptação nas 0, 3, 6, 9, 12 e 36 horas pós alimentação, quando o grupo não adaptado teve valores maiores que o grupo adaptado, sendo que na hora 24 ocorreu o contrário. Para a concentração de ácidos graxos de cadeia curta (AGCC), nas horas 0, 3, 6, 9 e 36 pós alimentação o grupo adaptado obteve maiores valores comparado ao grupo não adaptado. Para proporção molar de acetato, a 0 hora o grupo sem adaptação obteve valores maiores comparado ao grupo adaptado. Já nas horas 24, 27 e 30 o grupo com adaptação que obteve maiores valores. Para a proporção molar de propionato o grupo sem adaptação teve valores mais altos em comparação ao outro grupo das 3 às 36 horas pós alimentação. Quanto à proporção acetato:propionato (Ac:Pr) às 6, 12, 24, 27, 30 e 36 horas pós alimentação, o grupo de animais adaptados teve valores mais altos que o grupo não adaptado. Na proporção molar de butirato, o grupo de animais adaptados obteve maiores valores nas horas 0, 3, 6, 9, 12, 33 e 36. Para os valores de nitrogênio amoniacal (N-NH3), às 6 horas pós alimentação, o grupo não adaptado obteve maiores valores que o grupo adaptado (26,1 vs. 19,3, respectivamente). Nas horas 9, 30, 33 e 36 ocorreu o contrário. Observou-se também interação entre tempo e aditivo (P=0,0430) para a proporção molar de butirato. Porém, quando a análise foi realizada por tempo, nenhum efeito foi observado. Para os valores relativos de protozoários mensurados (Dasytricha, Isotricha, Epidinium, Diplodinium e Entodinium) apenas o Entodinium apresentou efeito de adaptação (P<0,0236) tendo sua proporção maior no grupo adaptado. Os valores de haptoglobina também não foram influenciados nem por aditivo nem por adaptação. O preparado de anticorpos policlonais não foi tão eficaz quanto a adaptação gradual à dieta de alto concentrado para controlar alterações dos parâmetros ruminais.<br>The objective of this trial was to evaluate the effects of polyclonal antibodies preparation (PAP) against specific rumen bacteria Streptococcus bovis and Fusobacterium necrophorum on rumen fermentation parameters in ruminally cannulated cows adapted or not to highly fermentable carbohydrates diets (HFC) after an acidosis challenge. The experimental design was two 3X3 Latin squares in a factorial arrangement of treatments 3X2 regarding two feed additives (PAP in powder presentation - PAPP and PAP in liquid presentation - PAPL) plus control group (CON) and two managements of diets adaptation, resulting in six treatments. The first Latin square had a step-up diet adaptation: from D0 to D4 100% forage; D5 to D9 30% of concentrates and D10 to D14 60% of concentrates. The second Latin square received 100% forage from D0 to D14. On D15 and D16, all animals received a diet with 80% of concentrates. For analysis, rumen fluid was sampled at 0 and every 3 h posfeeding totaling 36 h (D15 and D16) of challenge with a diet with 80% of concentrates. Data were analyzed by MIXED procedure with a significance level of 0.05. An interaction between time and adaptation (P<0,05) was observed for ruminal pH. At 0, 3, 6, 9, 12 and 36 h postfeeding, the non-adapted group had higher values compared to the adapted group and at 24 h postfeeding, the inverse was observed. For total short-chain fatty acids concentration, at 0, 3, 6, 9 and 36 h postfeeding, the adapted group had higher values compared to non-adapted group. For molar proportion of acetate at 0h postfeeding, the non-adapted group had higher values than the adapted group, and at 24, 27 and 30h, the adapted group had greater values than the non-adapted group. For molar proportion of propionate the non-adapted group had greater values compared to the adapted group from 3 to 36h postfeeding. For acetate:propionate (Ac:Pr) ratio at 6, 12, 24, 27, 30 and 36 h postfeeding, the adapted group had greater values compared to the nonadapted group. For butyrate molar proportion at 0, 3, 6, 9, 12, 33 and 36h postfeeding the adapted group had greater values than the non-adapted group. For ammonia nitrogen (NH3- N) concentration at 6h, the non-adapted group had greater values than the adapted group (26.1 vs. 19.3, respectively), however at 9, 30, 33 and 36h postfeeding, the adapted group had higher values compared to the non-adapted group. It was also observed an interaction between time and additive (P=0.0430) for butyrate molar proportion, but when the analysis was performed by time no effect was observed. For the relative values of protozoa measured (Dasytricha, Isotricha, Epidinium, Diplodinium and Entodinium) only Entodinium presented adaptation effect (P<0.0236) with a higher proportion in the adapted group. Haptoglobin values was also not influenced (P>0.05) by additive or adaptation effect. Polyclonal antibodies preparation was not as effective as the gradual adaptation to the diet high concentrate to control changes of ruminal parameters.
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Nienaber, Herman. "Effect of roughage to concentrate ratio on ruminal fermentation and protein degradability in dairy cows." Diss., Pretoria : [s.n.], 2008. http://upetd.up.ac.za/thesis/available/etd-02122009-151435.
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Atasoglu, Cengiz. "Regulation of amino acid and ammonia utilisation by ruminal microorganisms." Thesis, University of Aberdeen, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.327300.
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Lehmkuhler, Jeffrey W. "Feedlot cattle responses to ruminally undegradable protein /." free to MU campus, to others for purchase, 2001. http://wwwlib.umi.com/cr/mo/fullcit?p3036841.
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Guyader, Jessie. "Manipulation of the hydrogen pool available in the rumen to reduce methane emissions from ruminants." Thesis, Clermont-Ferrand 2, 2015. http://www.theses.fr/2015CLF22543/document.
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La réduction des émissions de méthane (CH 4) des ruminants permet de limiter les impacts environnementaux négatifs de leur élevage et d’améliorer leur efficacité digestive. Dans le rumen, le CH 4 est majoritairement produit par les méthanogènes à partir de l’hydrogène (H 2). La disponibilité de l’H 2 pour ces micro-organismes est réduite en limitant sa production par les protozoaires (via un apport de lipides ou extraits de plantes dans la ration) ou en stimulant des voies utilisatrices d’H 2 compétitives à la méthanogenèse (via un apport alimentaire de nitrate). Aucune étude n’a porté sur l’association de stratégies alimentaires jouant à la fois sur la production et l’utilisation d’H 2 pour diminuer les émissions de CH 4 . Notre objectif était de comprendre l’importance des différentes voies métaboliques de l’H 2 dans le rumen. Nous avons émis l’hypothèse que manipuler simultanément la production et l’utilisation de l’H 2 permet une diminution plus importante des émissions de CH 4 plutôt que d’agir sur un seul niveau. Nos résultats expérimentaux ont montré l’additivité de l’association lipides du lin-nitrate sur la méthanogenèse des bovins. Cet effet était persistant mais non bénéfique pour les performances digestives et laitières des animaux. L’association saponine de thé-nitrate n’a pas été efficace pour réduire les émissions de CH 4 car l’effet dépressif de la saponine sur les protozoaires n’a pas été observé. Cette thèse ouvre la possibilité d’étudier le potentiel anti-méthanogène de nouvelles associations de stratégies alimentaires ayant des mécanismes d’action différents dans le rumen. Les conditions d’utilisation de ces stratégies en élevage devront être délimitées, et leur rentabilité prouvée, pour être acceptées par l’éleveur<br>Reduction of methane (CH 4) emissions from ruminants may limit the negative environmental impacts of their breeding and may improve their digestive efficiency. In the rumen, CH 4 is mainly produced by methanogens from hydrogen (H 2). Hydrogen availability for these micro-organisms is reduced by limiting its production by protozoa (via lipids or plants extracts supplementation in diets) or by stimulating pathways competing with methanogenesis for H 2 consumption (via nitrate supplementation in diets). No study tested association of dietary strategies acting on both H 2 production and consumption to reduce CH 4 emissions. Our objective was to understand the importance of the different H 2 metabolic pathways in the rumen. We assumed that simultaneous manipulation of H 2 production and consumption reduces CH 4 emissions to a higher extent than acting on a single pathway. Our experimental results showed the additive CH 4 -mitigating effect of the association lipids from linseed-nitrate supplemented to bovine. This effect was persistent but not beneficial for digestive and lactating performances of animals. The association tea saponin-nitrate was not efficient to reduce CH 4 emissions, as the depressive effect of saponin towards protozoa has not been observed. This PhD thesis opens the possibility to study the anti-methanogenic potential of new association of dietary strategies having different mechanisms of action in the rumen. Conditions of use of these strategies at the breeding scale will have to be delineated, and their cost effectiveness proved to be accepted by farmers
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Armato, Leonardo. "Yeast cell walls and live yeasts diet supplementation in beef cattle: effect on rumen fermentations and ultrasonographic rumen wall findings." Doctoral thesis, Università degli studi di Padova, 2017. http://hdl.handle.net/11577/3422409.
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The objective of this thesis was to determine the effect of yeast supplements on the performance and health of beef cattle during the receiving and finishing period. Furthermore, another aim of this study was to evaluate the applicability of rumenocentesis on beef cattle and the viability of transabdominal ultrasonography of the rumen mucosa as a suitable, non-invasive diagnostic tool to identify beef cattle affected by SARA. Three trails were conducted in order to do achieve that. Trail I and Trail II were conducted simultaneously using the same animals, while the third trail used a larger sample but always in the same herd. Trail I and II assessed the effect of dietary supplementation of yeast cell wall (YCW) and live cell yeast (LY) at different dosages on rumen’s metabolites. Sixty Charolaise steers were divided into two groups on the basis of their feeding phase: growing and finishing. Growing and finishing groups were each randomly divided into equal three subgroups (n = 10): no supplement (growing control), supplemented with YCW, and supplemented with LY + YCW, no supplement (finishing control), supplemented with LY and supplemented with LY + YCW. Ruminal fluid has been collected before, after 21 and 42 days of experimental period in order to evaluate the volatile fatty acids concentrations and pH values. Faeces samples were collected before (T0), after 21 (T1) and 42 (T2) days of the start of the study, which took place simultaneously and analysed for dry matter (DM), Ash, crude protein (CP), ethereal extract (EE), neutral detergent fibre (NDF), acid detergent fibre (ADF), acid detergent lignin (ADL) and Starch detection. Dietary supplementation of LY and YCW increased (P<0.05) DM, ADF and ADL faecal concentrations in the growing phase; DM, ADL and Starch faecal concentrations in the finishing phase. T2/FC Diet showed a significant effect (P<0.001) of different diets respect to T2/FB in the finishing stage. The obtained results suggest that yeast supplementation do not have beneficial effects with all type of diet condition. Statistical analysis of VFA's data showed a significant effect of time (P < .05) on all studied parameters except iso-valeric acid both in growing and finishing groups. Changes among growing subgroups (P < .05) on propionic acid, acetic acid, iso-butyric acid and n-butyric acid were found, whereas no statistical significances were found among finishing subgroups. Trail III was conducted on 478 beef cattle of Charolaise breed, they were monitored three times during the livestock cycle in order to evaluating the rumen fluid pH and to assess the measures of the rumen wall: T0: 5±3 d after the arrival in farm;T1: 60±10 d after arrival; T2: 1 month before slaughter. Period effect (P<0.001) were found between the three periods after 10 days from the housing, rumen pH values were lower than the threshold value of 5.71 in T0 than in T1 and T2. Pearson’s analysis showed interaction between pH and total ultrasound thickness of rumen wall (-0.700; P<0.0001) and rumen mucosa (-0.7921; P<0.0001). Both differentiation efficiency of mucosal and submucosal layer thickness and rumen wall thickness between healthy and ruminal acidosis affected animals, as a result of ROC curve analysis, was excellent. Using a cut-off value of 5.4 mm, sensitivity was 96.30% and specificity was 91.60% on mucosal and submucosal layer. Using a cut-off value of 8.2 mm, sensitivity was 91.36% and specificity was 91.60 % on rumen wall thickness.
The study show that transabdominal ultrasonography of the rumen mucosa has the potential to be a suitable diagnostic tool to identify fattening bulls affected by SARA.<br>L'obiettivo di questa tesi era di determinare l'effetto degli integratori lievito sulle prestazioni e la salute dei bovini da carne durante il periodo di ricevimento e finissaggio. Inoltre, un altro obiettivo di questo studio era di valutare l'applicabilità di ruminocentesi sui bovini da carne e la possibilità di utilizzare l'ecografia transaddominale della mucosa ruminale come uno strumento diagnostico non invasivo per identificare i bovini affetti da SARA. Tre prove sono state condotte al fine di fare raggiungere questo obiettivo. Trail I e II sono stati condotti simultaneamente utilizzando gli stessi animali, mentre per la terza prova utilizzato un campione più grande, ma sempre nella stessa azienda zootecnica. Trail I e II ha valutato l'effetto della supplementazione alimentare di pareti di lieviti (JWC) e lievito cellule vive (LY) a diversi dosaggi di metaboliti nel rumine. Sessanta vitelloni di razza Charolaise sono stati divisi in due gruppi sulla base della loro fase di alimentazione: accrescimento e finissaggio. Il fluido ruminale è stato raccolto al tempo zero e dopo 21 e 42 giorni del periodo sperimentale al fine di valutare le concentrazioni degli acidi grassi volatili e del pH. I campioni di feci sono stati raccolti prima (T0), dopo il 21 (T1) e 42 (T2) giorni dall'inizio dello studio, e sono stati analizzati per sostanza secca (DM), ceneri, proteina grezza (CP), estratto etereo (EE), fibra neutra detergente (NDF), fibra detergente acido (ADF), acido detergente lignina (ADL) e amido.I risultati ottenuti suggeriscono che la supplementazione di lievito non hanno effetti benefici con tutti i tipi di condizione di dieta. L'analisi statistica dei dati di VFA ha mostrato un effetto significativo di tempo (P <.05) su tutti i parametri studiati, eccetto l'acido iso-Valerianico sia nei gruppi di crescita e di finissaggio. 408/5000
Sono stati riscontrati cambiamenti tra sottogruppi crescita (P <.05) su acido propionico, acido acetico, acido iso-butirrico e l'acido n-butirrico, mentre non è stata trovata significatività statistica tra sottogruppi del finissaggio. Trail III è stato condotto su 478 bovini da carne di razza Charolaise, sono stati monitorati per tre volte durante il ciclo di bestiame al fine di valutare il pH del fluido ruminale e per valutare le misure della parete ruminale.Effetto Periodo (P <0.001) è stato riscontrato tra i tre periodi dopo 10 giorni dall'arrivo. Valori di pH ruminale erano inferiori al valore di soglia di 5.71 in T0 rispetto al T1 e T2. L'analisi di Pearson ha mostrato interazione tra il pH e spessore ad ultrasuoni totale di parete ruminale (-0,700; p <0,0001) e del rumine mucosa (-0,7921; p <0,0001). Lo studio dimostrano che l'ecografia transaddominale della mucosa ruminale ha il potenziale per essere uno strumento diagnostico adatto per identificare i tori da ingrasso affetti da SARA.
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Mackintosh, E. D. "The effect of monensin on in vitro rumen fermentation and in vivo rumen and total tract digestion and milk production in the dairy cow." Thesis, University of Reading, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.265711.
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Olvera, RamiÌrez Andrea Margarita. "The effect of yeast (Saccharomyces cerevisiae) on pathogen survival and fermentation parameters in the rumen." Thesis, University of Aberdeen, 2007. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.487335.
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Enteric pathogens such as Escherichia coli 0157:H7 and Listeria monocytogenes have been identified as an important cause of human intestinal disease. Cattle and other ruminants appear to be the main reservoir of these food-borne pathogens. Reducing the carriage and shedding of these food-borne pathogens from their animal host would be of significance both for public health and economically. The objective of the present study was to investigate the effect of S.· cerevisiae on growth and/or survival of E coli 0157:H7 and L. monocytogenes in the rumen, using a combination of in vitro and in vivo experiments. Batch culture incubations showed that not all strains of S. cerevisiae could prevent the proliferation of E. coli 0157:H7 strain 12900R and L. monocytogenes in rumen fluid. This was confirmed in continuous culture (using the Rumen Simulation Technique: Rusitec) which demonstrated that somibut not all strains of yeast, could prevent the proliferation of E. coli 0157:H7 and L. monocytogenes and this anti-pathogenic effect seemed at least in part related to ability of the different strains of yeast to stimulate bacterial numbers in rumen. However, the distribution of the main bacterial species as indicated by 16S rDNA PCR-DGGE did not respond to yeast addition. Inoculation of pathogens into the rumen of multicannulated sheep in controlled feeding trials showed that 5 g d-1 of yeast tended to prevent the numbers of Listeria innocua from the rumen and this was associated with an increased total bacteria population. However, again the yeast did not have an effect on bacterial diversity assessed by 168 rONA PCR-DGGE. Furthermore, despite the decrease in pathogens leaving the rumen; yeast had no effect on shedding in the faeces. In a cattle trial with animals exposed to constant natural challenge of 20 g d-1 of yeast decreased the flow of Listeria leaving rumen and seemed to have an effect on pathogen shedding in faeces. In conclusion some but not all strains of S. cerevisiae reduced pathogen survival in the rumen; however, this was not always reflected in a decrease in faecal shedding.
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Ningrat, Rusmana Wijaya Setia. "Studies on Sapindus rarak DC as a defaunating agent and its effects on rumen fermentation." Thesis, University of Nottingham, 2005. http://eprints.nottingham.ac.uk/14437/.
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The aim of the work described here was to examine the antiprotozoal activity of the pericarp from Sapindus rarak DC (Sapindaceae) for its potential to defaunate the rumen, either partially or completely, without having a detrimental effect on the bacterial population and on rumen fermentation, and hence enhancing rumen productivity. An approach to improving microbial efficiency in the rumen is to eliminate protozoa (defaunation). Elimination of protozoa by chemical means is potentially the most convenient method. However, it is likely that some chemicals are not toxic specifically to the protozoa and probably kill other microorganisms and host cells in the rumen, therefore novel natural antiprotozoal agents are being sought. A possible role for saponins has been of interest to many researchers as saponins induce marked reductions in rumen protozoa numbers, particularly when the animal is fed on high-concentrate diets. The susceptibility of rumen protozoa and lack of susceptibility of rumen bacteria to saponins is explained by the reaction of saponins with membrane sterols, which are present only in eukaryotic membranes and not in prokaryotic bacterial cells. Recent in vitro results suggest that S. rarak exhibited higher immobilising activity and produce higher activity to lyse the cells compared to other saponin-containing plants. A preliminary study on the antiprotozoal activity of the active agent present in the pericarp of fruits of S. rarak, well known for the high saponin content of its fruits, was carried out. An antiprotozoal assay was developed. The results were consistent within experiments, but not between experiments, possibly due to the number of protozoa fluctuating widely with time. A study on the effect of Sapindus rarak on rumen bacteria, using a quantitative plating method, showed that there was no effect on rumen bacteria. Raw material and extract of pericarp of S. rarak were screened for their effects on rumen protozoa and bacteria (with a view to predicting its safety as a feed supplement and for its potential to defaunate the rumen, either partially or completely). The pericarp of S. rarak was extracted using selective extraction of saponins with CIS support. The fractions were collected and monitored by Thin Layer Chromatography (TLC). The active compounds were tested in vitro for toxicity to rumen protozoa by visual assessment of protozoal viability (Nottingham studies) and by measuring the degradation of labelled bacterial protein by rumen protozoa (Aberdeen studies). The influence of methanol extract of S. rarak on growth of pure cultures of rumen bacteria was also examined (Aberdeen studies). The results showed that the saponin fractions of S. rarak exhibit antiprotozoal activity as confirmed by visual assessment as well as by measurement of the breakdown of 14C-Ieucine-Iabelled Prevotella bryantti in rumen fluid incubated in vitro. No evidence was found of protozoal resistance to S. rarak. Inclusion of methanol extract of S. rarak in the growth medium of pure cultures of rumen bacteria had no effect, except that cellulolytic bacteria showed susceptibility. Extracts appeared in this study to prolong the lag phase following inoculation of Streptococcus bovis or inhibit the growth of Butyrifibrio fibrisolvens, Ruminococcos albus, and Ruminococcos flavefaciens. It seems that antibacterial properties were more pronounced against gram-positive bacteria, similar to the action ofionophores (McGuffey et al., 2001). A study on the effects of S. rarak on ruminal digestion, fermentation and ammonia concentration, using ruminally and duodenally cannulated dairy cows, showed that direct administration of S. rarak into the rumen did not decrease protozoal numbers in vivo. However, there were some indicators of selective activity against holotrichs. Changes in propionate concentration in the rumen and lack of change in microbial flow parameters suggest no adverse effects on other fermentation measures. Increased production of propionate is beneficial to the animal by affecting the capture of fermentation energy in the rumen. S. rarak caused a decrease in ammonia concentration. The observed ammonia levels represent a balance between the processes of degradation of feed protein and uptake of ammonia for synthesis of microbial protein. The lower ammonia levels could be due to higher incorporation of ammonia, peptide, or amino acids into microbial protein. In conclusion, S. rarak tested in this study has a great potential for suppressing rumen ciliate populations, but exerted negligible general effects on ruminal fermentation. Therefore, controlling rumen ciliate protozoa would be expected to lessen the dependence on protein supplementation under high-production conditions and would also be beneficial under conditions where the quantity of protein absorbed from the post-ruminal gut limits animal productivity, which occurs frequently in animals receiving low-quality tropical forages.
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Castagnino, Pablo de Souza. "Performance, carcass traits and rumen fermentation from feedlot nellore cattle fed crude glycerin and virginiamycin /." Jaboticabal, 2018. http://hdl.handle.net/11449/152871.
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Orientador: Telma Teresinha Berchielli<br>Coorientador: Giovani Fiorentini<br>Banca: Saulo da Luz e Silva<br>Banca: Otavio Rodrigues Machado Neto<br>Banca: Paulo Henrique Moura Dian<br>Banca: Juliana Duarte Messana<br>Resumo: O glicerol é um substrato utilizado por bactérias que metabolizam o lactato ruminal e a virginiamicina é um antibiótico não ionóforo que inibe o crescimento de bactérias gram-positivas produtoras de lactato. Foram realizados dois experimentos para avaliar os efeitos da glicerina bruta (GB) e da virginiamicina (VM) na ingestão, digestibilidade, fermentação ruminal, população microbiana, desempenho, características de carcaça e perfil de ácidos graxos da carne de bovinos Nelore. Os tratamentos experimentais foram organizados em um arranjo fatorial 2 × 2: dietas sem virginiamicina (VM-) ou 25 mg de virginiamicina/kg de matéria seca (VM+) combinadas com dietas sem glicerina bruta (GB-) ou 100 g de glicerina bruta/kg de matéria seca (GB+). O bagaço de cana-de-açúcar foi usado como forragem na proporção de 20% na matéria seca (MS) da dieta e a GB substituiu o milho na formulação da dieta. No primeiro experimento, foram utilizados oito bovinos Nelore fistulados no rúmen (Peso corporal = 600 ± 34 kg, 26 ± 3 meses) em um quadrado latino 4×4 replicado (período= 21 dias) para se avaliar a digestibilidade dos nutrientes, fermentação ruminal e população microbiana. A ingestão de MS teve uma tendência a aumentar em dietas com GB (P = 0,07). As digestibilidades aparentes totais dos nutrientes foram semelhantes entre as dietas (P ≥ 0,10). As dietas com GB ou VM apresentaram valores de pH similares (média = 6,15; P ≥ 0,10). A proporção de propionato aumentou 27,5% nas dietas com GB+, independ... (Resumo completo, clicar acesso eletrônico abaixo)<br>Abstract: Glycerol is a substrate used for bacteria that metabolize ruminal lactate and virginiamicyn is a non-ionophore antibiotic that inhibits the growth of gram-positive lactate-producing bacteria. Two experiments were conducted to evaluate the effects of crude glycerin (CG) combined with virginiamycin (VM) on intake, digestibility, ruminal fermentation, microbial population, performance, carcass traits and fatty acid profile of meat from feedlot Nellore cattle. Treatments were arranged in 2 × 2 factorial design: diets without virginiamycin (VM-) or virginiamycin at 25 mg/kg DM (VM+) combined with diets without crude glycerin (CG-) or CG (80% glycerol) at 100 g/kg DM (CG+). The sugar cane bagasse was used as the exclusive roughage in the proportion of 20% in the dry matter (DM) of diet and crude glycerin replaced corn in the diet formulation. In the first experiment, eight rumen fistulated bulls (BW= 600 ± 34 kg; 26 ± 3 months) were used in a replicated 4 × 4 Latin square (21-d periods) to evaluate the digestibility, ruminal fermentation and microbial population. The intake of DM had a tendency to be greater in CG+ than CG- diets (P = 0.07). Apparent total tract digestibilities of nutrients were similar among diets (P ≥ 0.10). Diets with CG or VM had similar values of pH (mean=6.15; P ≥ 0.10). The proportion of propionate increased 27.5% in CG+ diets, regardless of VM inclusion (P = 0.01). In the second experiment, forty-eight bulls with initial BW (408.4 ± 22.2 kg; 21 ± 2 months) ... (Complete abstract click electronic access below)<br>Doutor
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Gomez-Alarcon, Rogelio Alfonso. "Effects of Aspergillus oryzae on milk production, feed utilization and rumen fermentation in lactating dairy cows." Diss., The University of Arizona, 1988. http://hdl.handle.net/10150/184589.
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Two production trials were conducted for 84 d each. The first with 22 Holstein cows in late lactation. The second with 46 Holstein cows in early lactation. Treatments were C (control) and AO (A. oryzae 3g/d). Diets were for production trial 1 a 1:1 forage: concentrate ratio; for trial 2 was 2:3. Milk production in trial 1 was higher (P > .05) in AO fed cows during the first weeks of the trial. In trial two AO cows consistently produced more milk (P < .03). Rectal temperatures during hot weather (over 35°C) were consistently lower in AO fed cows, though not significant (P > .10). Two digestibility trials followed the production trials. For all digestion trials, Cr₂O₃ was used as digesta marker. In trial one AO tended to increase digestibility of DM (P > .10). In trial two digestibilities of DM, NDF and ADF were higher in AO fed cows (P < .05). Three other trials were conducted with mature Holstein cows fitted with ruminal and duodenal cannulae. The first trial tested two levels of forage (1:2 vs 2:1; forage to concentrate) and C vs AO in a 4x4 latin square design. AO increased (P < .05) ADF digestibility in the high concentrate died. No change (P > .10) in rumen pH, concentrations and proportions of VFA, and ammonia concentrations resulted from AO treatments. In the second trial C, AO and SC (Saccharomyces cerevesiae 3 g/d) were compared in a repeated 3x3 latin square design. A 1:2 forage to concentrate diet was fed to six lactating cows. Both AO and SC increased (P < .05) rumen NDF digestibility. The third trial compared C vs AO in a swithchback design with four lactating cows fed a 2:3 forage to concentrate diet. AO increased (P < .05) rumen fiber digestion. AO did not affect rates of passage of corn or alfalfa hay; or the potentially digestible DM of milo, alfalfa hay or wheat straw. AO did increase (P < .05) digestion rate of alfalfa DM. In vitro AO increased DM digestibility. That effect can be reproduced by incorporation of the additive at the time of inoculation.
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Silva, Zinaldo Firmino da [UNESP]. "Digestão e fermentação ruminal em vacas leiteiras recebendo glicerina bruta na dieta." Universidade Estadual Paulista (UNESP), 2011. http://hdl.handle.net/11449/104045.
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silva_zf_dr_jabo.pdf: 288941 bytes, checksum: c6a44e855aa5751be49544caeb8b11a1 (MD5)<br>Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)<br>Fundação de Amparo à Pesquisa e ao Desenvolvimento Científico do Maranhão (FAPEMA)<br>Avaliou-se efeito da inclusão de 0, 15 e 30% de glicerina bruta (GB) na matéria seca (MS) de dietas em substituição ao milho grão moído sobre o consumo de MS, produção de leite (PL), fermentação ruminal e digestibilidade da MS (DMS) em vacas leiteiras. Foram utilizadas seis vacas multíparas, da raça Holandesa providas de cânula permanente de 4” no rúmen, estando no início do experimento com peso médio de 587 ± 39 kg, com 114 ± 29 dias em lactação e produzindo média de 20 ± 1,5 kg/leite em duas ordenhas diárias. As vacas foram distribuídas em dois quadrados latinos 3 x 3 com períodos de 21 dias, sendo 14 de adaptação. As dietas continham silagem de milho, milho grão, farelo de girassol, glúten de milho, uréia, vitaminas, minerais e GB (86% de glicerol, 95% MS, 6% sais e <100 g/kg de metanol) e foram oferecidas ad libitum, duas vezes ao dia, na forma de dieta total. A dieta controle - ausência de GB, continha 36% de milho; a dieta com 15% e 30% de GB continham, respectivamente, 19,3 e 2,8% de milho. A utilização da GB na dieta reduziu a PL (P=0,10), o consumo de MS (P=0,08), os tempos gastos com atividade mastigatória (P<0,03), a digestibilidade da FDN (P<0,04) e a produção de bactérias associadas à fase líquida do rúmen (P=0,04). Não foram observadas diferenças quanto a cinética de degradação e passagem. Porém, houve aumento na concentração de metano quando a GB foi incluída na dieta. A utilização de glicerina bruta (86% de glicerol) em 15% da matéria seca da dieta de vacas em lactação deprime produção de bactérias de fase líquida, digestibilidade da fibra e desempenho. A sua inclusão em até 10% parece ser o limite ótimo<br>The purpose of this work was to evaluate the effect of the inclusion of 0, 15 and 30% crude glycerin (CG) in the MS diet in replacement of corn grain (diet control) on the ground on the dry matter intake (DMI), milk production (MY), rumen fermentation and dry matter digestibility in dairy cows . We used six multiparous Holstein cows rumen cannulated, being at the experiment with 587±39 kg BW, 114±29 DIM and with average 20±1.5 kg/d MY in two daily milkings, distributed in two 3x3 Latin Square with 21-days periods. The diets contained corn silage (45% DM), corn grain, sunflower meal, corn gluten meal, urea, vitamins, minerals and CG (86% glycerol, 95% DM, salts 6% and <0.1ppm of methanol). Cows were individually fed on total mixed ration in twice daily. The control diet - no glycerin, containing 36% corn, the diet with 15% and 30% contained GB, respectively, 19.3 and 2.8% of the corn. The use of the CG in the diet reduced the MY (P=0.10), DMI (P=0.08), the time chewing activities (P<0.03), NDF digestibility (P=0.04) and the liquid-associated bacteria content (P=0,04). There were no differences in the kinetics of degradation and passage. However, increased methane output when GB was in the diet. The use of crude glycerin (86% glycerol) in 15% of the diet dry matter for lactating cows depresses production of bacteria in the liquid phase, fiber digestibility and performance. Inclusion in up to 10% seems to be the optimum limit
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Romagnolo, Donato. "Ruminal degradability of subfractions of protein sources as determined by gel electrophoresis." Thesis, Virginia Tech, 1988. http://hdl.handle.net/10919/45176.
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Degradability in the rumen of several protein sources was determined by suspending from 12 to 13 g of feedstuff in dacron bags into the rumen for 0, 2, 6, 12, 24, 36, 48, and 72 h. Rumen cannulated lactating Holstein cows consuming a diet of corn silage, alfalfa, soybean, and high moisture corn were used. Degradability of protein varied from 18.6% for corn gluten meal to 72.3% for soybean meal. Gel electrophoresis was used to monitor rates of degradation in the rumen of fractions of corn gluten (CGM), CORN, cottonseed (CSM), peanut (PM), and soybean meal (SBM) protein fractions. Fractional degradation rates in the rumen were determined from densitometric analysis of stained polypeptides bands on SDS-PAGE gels. Acidic subunits of soybean glycinin were degraded at a faster rate than basic subunits (.144 vs .104 h⁻¹). Rates of degradation of zein in corn and corn gluten meal were .026 and .015 h⁻¹, respectively. Protein degradability estimated by using B subfractional components did not differ from degradability measured using total B fractions. Lag phase associated with dacron bags suspension technique did not change effective degradability. Protein solubility in SDS-PAGE sample buffer was highly correlated (R²=.958) with in situ protein degradability of CORN, CSM, DBG, FM, PM, and SBM. Different rates of degradation of each fraction may directly influence protein and amino acid contribution to the animal.<br>Master of Science
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Restrepo, P. Ricardo J. "Dry matter digestibility and VFA production of selected feedstuffs using RUSITEC /." free to MU campus, to others for purchase, 1998. http://wwwlib.umi.com/cr/mo/fullcit?p9901273.
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DELFINO, FRANCIS JOSEPH. "IDENTIFICATION AND CHARACTERIZATION OF CEREAL GRAIN TISSUES RESISTANT TO RUMEN MICROBIAL DIGESTION USING IN SITU, IN VITRO AND SCANNING ELECTRON MICROSCOPY TECHNIQUES." Diss., The University of Arizona, 1986. http://hdl.handle.net/10150/183909.
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A series of studies was conducted using SEM in conjunction with chemical analysis, in situ and in vitro digestion techniques, to characterize the anatomical components from barley, corn, sorghum and wheat grains which constitute "fiber" and investigate their susceptibility to rumen microbial digestion. Fractured grains were used to identify anatomical features and cell types prior to and after extraction or digestion. Certain anatomical features, including pericarp tissue, aleurone cells, endosperm cell walls, corneous and floury endosperm tissue and lemma and palea from barley, were easily identifiable in fractured and ground grains, and in neutral detergent extracted or digested residues. In situ and in vitro incubation conditions were varied to assess the effect of concentrate and/or reduction of pH on the disappearance of identifiable grain fractions. In situ incubations were conducted using steers adapted to 0-, 30- and 90% concentrate diets. In vitro inoculum buffered at pH 7 or 6 was provided by a steer fed 0- or 90% concentrate. Tissues resistant to rumen microbial digestion during extended (144-h) in situ incubations and shorter term (12- to 48-h) in vitro incubations were primarily those identified in NDF, and included pericarp, lemma and palea, and small amounts of corneous endosperm. Remaining tissues identified included barley lemma, palea and pericarp; corn pericarp, tip cap and small amounts of corneous endosperm; sorghum pericarp and corneous endosperm with matrix and protein bodies; and wheat pericarp. In vitro disappearance of isolated NDF after 48-h ranged from 43% for barley to 89% for corn. Labile structures included embryonic tissue and portions of endosperm cell walls, protein matrix and residual starch. Resistant tissues included pericarp, aleurone cell walls, tip cap and portions of the corneous endosperm. Relative rankings of NDF digestibility under all conditions studied were similar (corn > sorghum > wheat > barley) whether determined using isolated NDF or calculated from TIVDMD residues. Neither concentrate level fed to the host animal nor pH of the in vitro incubation flask affected rankings among grains, although increasing concentrate level and/or reducing pH appeared to reduce in vitro NDF disappearance. Evaluation of electron micrographs of fractured grains suggested that similar anatomical structures in the various grains differed in their resistance to microbial digestion. For example, pericarp from barley and wheat appeared to be more resistant than that from corn or sorghum. Endosperm of barley was less resistant than that of sorghum.
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Barbi, Jose Henrique Tostes. "Use of the Rumen Simulation Technique (RUSITEC) to provide micro-organisms to assess in vitro rate of fermentation of forages." Thesis, University of Reading, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.309503.
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Deml, Mirko [Verfasser], Wilhelm [Akademischer Betreuer] [Gutachter] Windisch, and Michael [Gutachter] Pfaffl. "Effects of supplementing amylase and potease to ruminant diet on rumen fermentation characteristics and the rumen microbiota / Mirko Deml ; Gutachter: Wilhelm Windisch, Michael Pfaffl ; Betreuer: Wilhelm Windisch." München : Universitätsbibliothek der TU München, 2017. http://d-nb.info/1135385548/34.
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Ruseckaitė, Irena. "Pašarų organinės medžiagos virškinamumo priklausomybė nuo karvių didžiojo prieskrandžio turinio fermentacijos lygio." Master's thesis, Lithuanian Academic Libraries Network (LABT), 2008. http://vddb.library.lt/obj/LT-eLABa-0001:E.02~2008~D_20080318_135555-53731.
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Bandymas atliktas siekiant ištirti didžiojo prieskrandžio biocheminius ir mikrobiologinius rodiklius, šeriant karves skirtingos sudėties racionais; įvertinti didžiojo prieskrandžio fermentacinį aktyvumą; ištirti žolinių pašarų – šieno, šienainio, kukurūzų siloso virškinamumą in vitro, inkubuojant juos su skirtingo fermentacinio aktyvumo didžiojo prieskrandžio turiniu.
Iš gautų rezultatų galime teigti, kad skirtingos sudėties racionai turi įtakos karvių didžiojo prieskrandžio turinio mikrobiologiniams ir biocheminiams rodikliams. Nustatyta, kad I (kontrolinės) grupės karvių didžiojo prieskrandžio turinio ph buvo 10,5 proc. (p<0,0001) mažesnis; redukcinis bakterijų aktyvumas vyko 131 s (p<0,0001) greičiau; gliukozės rūgimo reakcija buvo 71,4 proc. (p<0,0001) didesnė; pirmuonių rasta 120 103/ (p<0,0001) daugiau; LRR gamyba padidėjo 27,2 proc. palyginant su II (bandomosios) grupės karvėmis, kurios buvo šeriamos nesubalansuotu racionu.
Subalansuoto raciono įvairesni ir maistingesni pašarai nulėmė, kontrolinės grupės aktyvesnį didžiojo prieskrandžio turinio fermentacinį procesą. Subalansuotame racione vyravo šienainis (55 proc.), kukurūzų silosas (20 proc.) ir kombinuotieji pašarai (20,7 proc.). Racionas buvo praturtintas melasa (0,62 proc.) ir BVMP (0,37 proc.).
Bandomosios karvės iš sultingųjų pašarų gavo tik kukurūzų siloso, kuris ir sudarė didžiausią raciono dalį (75 proc.). Jų racione nebuvo šienainio, kuris yra 2-3 kartus maistingesnis palyginti su kukurūzų silosu (2... [toliau žr. visą tekstą]<br>Aim of thesis: to analyse the dependence of forage organic material digestion on the level of cows’ long prestomach fermentation.
Tasks: 1. To estimate biochemical and microbiological factors of large prestomach content of cows, fed by different consist rations and to evaluate fermentational activity; 2. To examine herby forage- hay, haylage and maize silage- organic material digestion in vitro by incubating them with different fermentational activity content of long prestomach.
In the course of work the following was identified: 1. Ph of long prestomach content of cows fed by balanced ration was 10,5 % (p<0,0001) lower, the reaction of bacteria reductional activity was 131 s (p<0,0001) faster, the reaction of glucoses fermentation was 71,4 % (p<0,0001) higher, protoza was found 120 103 / ml (p<0,0001) more, the production of free fatty acids increased by 27,2 % (p<0,0001) in comparison with cows, which were fed by unbalanced ration. 1.1. Therefore fermentational processes of long prestomach of cows fed by balanced ration were active, and of those fed by unbalanced ration- slowed down. 2. When incubating hay, haylage and silage in vitro with different fermentational activity content of long prestomach, organic material digestion (OMD) of all examined forage was highest by incubating them with active fermentation long prestomach content: 2.1. organic material digestion (OMD) was of hay 5,52 % (p<0,0001) higher; organic material digestion (OMD) was of haylage 5,5 % (p<0,0001)... [to full text]
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Batallas, Carlos Eduardo. "The Effects of Feeding a High Level of Rumen Protected Fat with Rumen Undegradable Protein With or Without Niacin on Rumen Fermentation Characteristics, Apparent Nutrient Digestibility, and Milk Production in the Early to Mid Lactation Holstein Cow." DigitalCommons@USU, 1992. https://digitalcommons.usu.edu/etd/4075.
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Forty high producing early to mid lactation Holstein cows were blocked according to stage of lactation and previous two-week milk yield (experiment 1) . Eight ruminally and duodenally cannulated nonlactating Holstein cows were used for experiment 2. The objective was to determine the effects of the ration's high fat content (11.53%) when rumen degradable or rumen undegradable protein is fed with or without added niacin. Cows received one of five treatments: 1) basal ration (TMR); 2) basal ration with added rumen undegradable fat (RUF) (1.6 kg); soybean meal (SBM) (1.73 kg), and niacin (12 g); 3) same as treatment 2, without niacin; 4) same as treatment 2 but replacing the soybean meal with undegradable protein (UIP) (1.9 kg ) ; and 5) same as treatment 4, without niacin. Rations and water were offered ad-libitum for 10 weeks. Intake for experiment 2 was limited to 18 kg TMR, 0 .76 kg RUF, 0 .88 kg SBM or UIP, and 6 g niacin. All cows in experiment 2 received the five treatments by the end of five collection periods separated by 21 d adaption. RUF increased dry matter intake (22.95 vs. 23 . 72 kg/d ) and mean body weight (607 vs. 637 kg ) , but decreased milk protein, lactose and SNF (proportion and yield); and 4% FCM without affecting daily milk yield. RUF, SBM, and N did not affect milk production. Milk protein percentage, protein yield, lactose percentage, SNF percentage, and yield were decreased by UIP supplementation. Niacin had a negative effect on milk fat percentage and yield, and milk protein percentage when fed with RUF and UIP . Supplements did not affect milk protein components. RUF increased plasma glucose (56.8 vs. 63.5). RUF addition increased AD and ND digestibility while decreased fatty acid digestibility. UIP improved ND digestibility in the lactation trial. For experiment 2, UIP increased rumen propionate percentage, thus reducing acetate to propionate ratio. Niacin increased total VFA production (128.6 vs. 114.3 umol/ml) . RUF, UIP, and niacin increased total bacterial population. RUF reduced cellulolytic bacteria in rumen fluid. Nutrient rate of passage and digestibility were unaffected by treatments except for dry matter and RUF digestibility that were reduced by RUF supplementation.
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Guy, Christine. "Etude et modélisation des produits du métabolisme microbien et de la dégradation des composés pariétaux en fermenteur semi-continu par les microorganismes du rumen." Toulouse, INPT, 1988. http://www.theses.fr/1988INPT018G.
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Wettstein, Hans-Rudolf. "Influence of plant lecithins on rumen fermentation, lipid digestion and quality of milk and body fat in cattle /." [S.l.] : [s.n.], 2000. http://e-collection.ethbib.ethz.ch/show?type=diss&nr=13721.
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Grimsell, Ashley. "Effect of protein source and quality on feedlot growth performance and rumen fermentation characteristics of Dohne Merino lambs." Diss., University of Pretoria, 2020. http://hdl.handle.net/2263/77824.
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The importance of protein quality in the formulation of ruminant rations has been regarded as inconsequential in the past. Moreover, the use of agro-industrial by-products as feed ingredients have become attractive alternatives in the animal feed industry, whereby several of these products characteristically have alternative protein qualities. Dried brewer’s grains (DBG) is a by-product originating from the beer manufacturing industry, frequently incorporated in the diets of feedlot lambs, however, has caused obstacles in some feed mills in South Africa. The oilseed by-products: canola-, soybean- and cottonseed meal, have all been proposed as suitable protein sources which can be included lamb feedlot diets. In this study, DBG, canola meal, soybean meal and cottonseed meal were incorporated as protein sources into concentrate-rich feedlot lamb diets. All experimental diets were formulated to contain 14% crude protein (CP) and 10.2 MJ ME/kgDM. The four experimental treatments differed in terms of the inclusion of the primary protein source which was either DBG, canola meal, soybean meal or cottonseed meal. Two experiments were conducted. The first experiment, comprising a feedlot growth experiment, utilized a randomised complete block design (RCB) as the experimental design. It was conducted using 200 Dӧhne-Merino lambs in order to investigate the effect of protein quality on the growth performance, feed intake and carcass parameters. The average total weight gained over the duration of the feedlot growth trial, as well as the average daily gain (ADG) of the canola meal treatment, was lower (P<0.05) than the other three treatments. Higher (P<0.05) feed intakes were realised on the cottonseed meal diet as opposed to the other three treatments. Additionally, lower (P<0.05) feed intakes were realised on the DBG diet when compared to the other three treatments. The feed
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conversion ratio (FCR) of the DBG diet was better (P<0.05) than the canola-, soybean- and cottonseed meal treatments, respectively. Conversely, the FCR realised for the canola meal diet was poorer (P<0.05) than the other three treatments. The lower (P<0.05) final live weights of the lambs from the DBG treatment, in comparison to those from the canola meal and cottonseed meal treatments, translated into lower (P<0.05) hot and cold carcass mass. Carcass classification remained unaffected (P>0.05) by treatment. Nevertheless, dissimilarities (P<0.10) were detected in the dressing percentages of the canola meal treatment and cottonseed meal treatment, whereby the dressing percentages of the former were higher. The second experiment entailed four mature cannulated wethers being subjected to a 4×4 Latin square design in order to investigate the effect of protein quality on the intake, apparent total tract digestibility, degradability and some rumen fermentation parameters of the sheep. Feed intake was greater (P<0.05) for the DBG diet as opposed to the soybean meal diet. Thus, the feed intake results of the two separate experiments differed from one another. The apparent DM digestibility of the DBG diet was lower (P<0.10) than the soybean meal diet. A higher (P<0.05) apparent CP digestibility was realised on the soybean meal diet, as opposed to the DBG and canola meal diets. The apparent total tract starch and NDF digestibility remained unaffected (P>0.05) by treatment for the current study. A lower dry matter (DM) degradability estimate (P<0.05) was realised for DBG, when compared to the other three treatments. No differences (P>0.05) were detected in the CP degradability estimates between the four respective protein concentrates, however could have been predisposed to experimental error. Average ruminal pH was higher (P<0.05) for the cottonseed meal diet, as opposed to the other three treatments and average ruminal ammonia nitrogen concentration did not differ (P>0.05) between treatments. The results advocate that protein quality has the potential to influence growth parameters, digestibility and rumen fermentation in sheep. Further research needs to be conducted on the inclusion levels of the respective protein concentrates and the breakpoint in the feeding period, where protein quality can be regarded as not important anymore.<br>Dissertation (MSc (Agric))--University of Pretoria, 2020.<br>Animal and Wildlife Sciences<br>MSc (Agric)<br>Unrestricted
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Ramihone, Bruno. "Facteurs limitant la fermentation dans le rumen des pailles de céréales (à petits grains) traitées à l'ammoniac anhydre." Montpellier 2, 1987. http://www.theses.fr/1987MON20281.
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Le traitement des pailles a l'ammoniac augmente leur digestibilite, leur ingestibilite et leur teneur en equivalent matieres azotees, mais la valorisation de ces pailles par les ruminants pose encore des problemes lies a la mauvaise cellulolyse dans le rumen. Les causes possibles de cette derniere sont recherchees: action des acides phenoliques et de l'azote
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Ramihone, Bruno. "Facteurs limitant la fermentation dans le rumen des pailles de céréales (à petits grains) traitées à l'ammoniac anhydre." Grenoble 2 : ANRT, 1987. http://catalogue.bnf.fr/ark:/12148/cb37609088s.
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Dschaak, Christopher M. "Use of Rumen Modifiers to Manipulate Ruminal Fermentation and Improve Nutrient Utilization and Lactational Performance of Dairy Cows." DigitalCommons@USU, 2012. https://digitalcommons.usu.edu/etd/1238.
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Overall hypothesis in a series of lactation studies reported in this dissertation was that supplementing different rumen modifiers would have consistent responses on ruminal fermentation and lactational performance under optimal ruminal fermentative conditions. First experiment investigated the influence magnesium exchanged zeolite on ruminal fermentation and lactational performance. Intake of dry matter (DM), milk yield, milk fat concentration, and feed efficiency were not affected. Milk protein concentration tended (P = 0.15) to be higher for the zeolite total mixed ration (TMR). Ruminal pH tended to increase (P = 0.11) by feeding the sodium bicarbonate or the zeolite. A second lactation experiment determined the influence of quebracho condensed tannin extract (CTE) on ruminal fermentation and lactational performance. Supplementing CTE decreased intakes of DM and nutrients regardless of forage level thereby increasing feed efficiency. Milk yield and components were not affected. Milk urea N (MUN) and total VFA concentration decreased by supplementing CTE. Cows fed CTE had decreased ruminal ammonia-N and MUN concentrations, indicating that less ruminal N was lost as ammonia. A third lactation trial assessed whole safflower seeds (SS) on ruminal fermentation, lactational performance, and milk fatty acids. Feeding the Nutrasaff SS TMR (NSST) decreased intake of neutral detergent fiber. Digestibilities of nutrients, milk yield and components, ruminal pH, ruminal VFA, and ammonia-N were similar. Ruminal C16:0 fatty acid (FA) concentration increased with the cottonseed TMR (CST), while C18:1 cis-9 and C18:2 n-6 tended (P = 0.10 and P = 0.09, respectively) to increase with SS supplementation. Supplementing SS decreased milk C16:0 concentration, whereas it increased C18:1 cis-9 and C18:1 trans-9. Milk C18:1 trans-11 FA and cis-9, trans-11 conjugated linoleic acid increased and tended (P = 0.07) to increase with feeding the NSST. Feeding zeolite would cost-effectively replace sodium bicarbonate as a ruminal buffer, whereas CTE may change the route of N excretion, having less excretion into urine, but more into feces. Whole SS can be an effective fat supplement to lactating dairy cows without negative impacts on lactational performance and milk FA. These studies demonstrate that the three rumen modifiers can positively manipulate ruminal fermentation.
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Yang, Chongwu. "Evaluation of Inhibitors of Lysozyme and Peptidases as New Approaches to Control Growth of Rumen Protozoa." The Ohio State University, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=osu1500471429645685.
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Silva, Zinaldo Firmino da. "Digestão e fermentação ruminal em vacas leiteiras recebendo glicerina bruta na dieta /." Jaboticabal : [s.n.], 2011. http://hdl.handle.net/11449/104045.
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Orientador: Jane Maria Bertocco Ezequiel<br>Banca: Juliana Borsari Dourado Sancanari<br>Banca: Weber Vilas Bôas Soares<br>Banca: Mauro Dal Secco de Oliveira<br>Banca: Atushi Sugohara<br>Resumo: Avaliou-se efeito da inclusão de 0, 15 e 30% de glicerina bruta (GB) na matéria seca (MS) de dietas em substituição ao milho grão moído sobre o consumo de MS, produção de leite (PL), fermentação ruminal e digestibilidade da MS (DMS) em vacas leiteiras. Foram utilizadas seis vacas multíparas, da raça Holandesa providas de cânula permanente de 4" no rúmen, estando no início do experimento com peso médio de 587 ± 39 kg, com 114 ± 29 dias em lactação e produzindo média de 20 ± 1,5 kg/leite em duas ordenhas diárias. As vacas foram distribuídas em dois quadrados latinos 3 x 3 com períodos de 21 dias, sendo 14 de adaptação. As dietas continham silagem de milho, milho grão, farelo de girassol, glúten de milho, uréia, vitaminas, minerais e GB (86% de glicerol, 95% MS, 6% sais e <100 g/kg de metanol) e foram oferecidas ad libitum, duas vezes ao dia, na forma de dieta total. A dieta controle - ausência de GB, continha 36% de milho; a dieta com 15% e 30% de GB continham, respectivamente, 19,3 e 2,8% de milho. A utilização da GB na dieta reduziu a PL (P=0,10), o consumo de MS (P=0,08), os tempos gastos com atividade mastigatória (P<0,03), a digestibilidade da FDN (P<0,04) e a produção de bactérias associadas à fase líquida do rúmen (P=0,04). Não foram observadas diferenças quanto a cinética de degradação e passagem. Porém, houve aumento na concentração de metano quando a GB foi incluída na dieta. A utilização de glicerina bruta (86% de glicerol) em 15% da matéria seca da dieta de vacas em lactação deprime produção de bactérias de fase líquida, digestibilidade da fibra e desempenho. A sua inclusão em até 10% parece ser o limite ótimo<br>Abstract: The purpose of this work was to evaluate the effect of the inclusion of 0, 15 and 30% crude glycerin (CG) in the MS diet in replacement of corn grain (diet control) on the ground on the dry matter intake (DMI), milk production (MY), rumen fermentation and dry matter digestibility in dairy cows . We used six multiparous Holstein cows rumen cannulated, being at the experiment with 587±39 kg BW, 114±29 DIM and with average 20±1.5 kg/d MY in two daily milkings, distributed in two 3x3 Latin Square with 21-days periods. The diets contained corn silage (45% DM), corn grain, sunflower meal, corn gluten meal, urea, vitamins, minerals and CG (86% glycerol, 95% DM, salts 6% and <0.1ppm of methanol). Cows were individually fed on total mixed ration in twice daily. The control diet - no glycerin, containing 36% corn, the diet with 15% and 30% contained GB, respectively, 19.3 and 2.8% of the corn. The use of the CG in the diet reduced the MY (P=0.10), DMI (P=0.08), the time chewing activities (P<0.03), NDF digestibility (P=0.04) and the liquid-associated bacteria content (P=0,04). There were no differences in the kinetics of degradation and passage. However, increased methane output when GB was in the diet. The use of crude glycerin (86% glycerol) in 15% of the diet dry matter for lactating cows depresses production of bacteria in the liquid phase, fiber digestibility and performance. Inclusion in up to 10% seems to be the optimum limit<br>Doutor
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Doherty, John Gerard. "The effect of differences in silage fermentation and concentrate source on rumen and milk production parameters in dairy cows." Thesis, Queen's University Belfast, 1994. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.241388.
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Huang, Yayu. "Effect of live yeast on the fermentation and microbiological physico-chemical parameters of the rumen, depending on the nature of the diet : modeling and validation in ruminant." Thesis, Toulouse, INPT, 2018. http://www.theses.fr/2018INPT0003.
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L'acidose ruminale est l'une des préoccupations majeures des exploitations laitières actuelles. Les levures vivantes (LV) ont été largement étudiées et utilisées chez les vaches laitières pour stabiliser la fermentation ruminale. Récemment, la mesure du potentiel redox ruminal (Eh, en mV) a été considérée comme un outil intéressant pour indiquer le trouble de la fermentation ruminale. L'effet positif de LV sur Eh ruminal a été rapporté, mais il reste variable selon les conditions expérimentales. Les objectifs de ce travail étaient de fournir une meilleure compréhension du mode d'action de LV et de définir la condition optimale de l'utilisation de LV chez les vaches laitières. La première partie de ce travail a consisté en une analyse quantitative des résultats de 22 expériences avec des vaches laitières canulées. La deuxième partie de ce travail a consisté à vérifier certains des résultats de l'analyse quantitative par une expérience chez des vaches en lactation. En utilisant l'analyse quantitative de données existantes provenant d'expériences antérieures, nous avons clarifié la relation entre le Eh ruminal et d'autres paramètres ruminaux principaux tels que le pH et le profil VFA, et suggéré que les variations de Eh pourraient être liées au transfert d'électrons dans les réactions dans le rumen. En outre, la réponse du Eh après la supplémentation en LV était également liée à celle du profil AGV ruminal, suggérant que l'effet de LV sur le profil VFA était atteint par l'augmentation du pouvoir réducteur, reflétant un meilleur transfert d'électrons dans le rumen. L'analyse a en outre démontré que la régulation du Eh ruminal par LV serait particulièrement efficace lorsque le risque de troubles digestifs est élevé. Puisque l'influence des caractéristiques de la ration sur le Eh ruminal a été quantifiée, l'effet de LV dans un régime donné pourrait être estimé indirectement. En outre, l'analyse quantitative a également révélé que la réponse de Eh suite à la supplémentation en LV était associée à la quantité de sucres solubles ingérée. L'expérience in vivo chez des vaches en début de lactation a confirmé un effet plus important de LV sur Eh ruminal avec une ration riche en sucres solubles, et a démontré que la supplémentation en LV avait un impact sur la richesse des bactéries, et que les métabolites ont également été influencés par la supplémentation en LV, probablement associée à la diminution du Eh ruminal<br>Ruminal acidosis is one of the major concerns of current dairy farms. Live yeasts (LY) have been extensively studied and used in dairy cows for stabilization of rumen fermentation. Recently, measurement of ruminal redox potential (Eh, in mV) has been considered as an interesting tool to indicate ruminal fermentation disorder. The positive effect of LY on ruminal Eh has been reported, but it remains variable according to the experimental conditions. The aims of this work was to provide better understanding of mode of actions of LY, and to define the optimal condition of LY utilization in dairy cows. The first part of this work consisted to quantitative analysis of existing results from 22 experiments with cannulated dairy cattle. The second part of this work consisted to verify some of the results from quantitative analysis by an in vivo experiment in lactating cows. By using quantitative analysis of existing data from previously conducted experiments, we clarified the relationship between ruminal redox and other main ruminal parameters such as pH and VFA profile, and suggested that Eh variations might be related to the transfer of electrons in the reactions producing VFAs in the rumen. Moreover, response of ruminal Eh following live yeast supplementation was also related to that of ruminal VFA profile, which suggested that the effect of LY on VFA profile was achieved via the increase of reducing power, possibly reflected improved electron transfer and use in the rumen. The analysis further demonstrated that the regulation of ruminal Eh by LY would be particularly effective when risk of digestive disorder is high. Since the influence of dietary characteristics on ruminal Eh was quantified, the effect of LY in a given diet could be indirectly estimated. In addition, quantitative analysis also associated the response of ruminal Eh following LY supplementation to the intake of soluble sugars. The in vivo experiment in early-lactating cows confirmed greater effect of LY on ruminal Eh in diet rich in soluble sugars, and further demonstrated that i) LY supplementation tended to impact the richness of ruminal bacteria, and ii) some unidentified metabolites were also influenced by LY supplementation, probably associated to the decrease of ruminal Eh