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O objetivo deste estudo foi avaliar a ocorrência de diarreia e suas consequências no metabolismo animal em bezerros consumindo concentrado inicial contendo coprodutos como polpa cítrica, melaço e xarope de glicose; ou bezerros suplementados com probiótico. Dois experimentos foram conduzidos para avaliar o efeito da substituição de milho por coprodutos. No primeiro experimento, 24 bezerros com idade média de 2 semanas, foram distribuídos em 3 tratamentos e receberam concentrado inicial contendo doses crescentes de polpa cítrica em substituição ao milho. No segundo experimento, 32 bezerros foram divididos em 4 tratamentos, recebendo concentrado inicial contendo xarope de glicose e doses crescentes de melaço em substituição ao milho. Em ambos os experimentos, os animais foram alojados em abrigos individuais, receberam 4 L de sucedâneo lácteo por dia, dividido em duas refeições e tiveram livre acesso à água e concentrado. Após o diagnóstico da ocorrência de diarreia, foram realizadas avaliações de escore fecal, escore clínico, além de medição dos parâmetros fisiológicos, nas seguintes 24, 48 e 72 horas. Foram colhidas amostras de sangue para realização de hemograma, análises bioquímicas, análises gasométricas e eletrolíticas. A adição de coprodutos no concentrado inicial não afetou (P>0,05) o escore fecal, as características das fezes e os sinais clínicos dos animais diarreicos. As análises plasmáticas bioquímicas (glicose, proteínas totais, albumina, ?-hidroxibutirato, nitrogênio ureico plasmático, lactato total, D- e L-lactato) apresentaram valores normais e não sofreram efeito negativo (P>0,05) em resposta da substituição de milho por coprodutos no concentrado. Não houve diferença entre os tratamentos (P>0,05) nas análises gasométricas e no eritrograma, com resultados indicando ausência ou baixo nível de acidose metabólica e desidratação nos animais. De acordo com o leucograma realizado, foi constatada leucocitose e neutrofilia na maioria dos casos, significando que a diarreia foi de origem infecciosa, descartando a possibilidade que o consumo de coprodutos no concentrado fosse a etiologia da diarreia. Um terceiro experimento foi realizado para avaliar o desempenho geral de bezerros suplementados com probíóticos contendo bactérias ruminais. Foram utilizados 20 bezerros divididos em 2 tratamentos (controle e fornecimento oral de 2 gramas de probiótico/dia), sendo os animais avaliados até a 10ª semana de vida. Os animais alojados em abrigos individuais, receberam 6 L de sucedâneo lácteo por dia, e tiveram livre acesso à água e concentrado. O desaleitamento foi realizado na 6ª semana de vida, de forma a causar uma situação de estresse nos animais. O consumo diário de concentrado, ganho de peso, desenvolvimento corporal e escore fecal foram avaliados. Nas semanas 2, 4, 6, 8 e 10 foram colhidas amostras de sangue para determinação de parâmetros bioquímicos e realização do hemograma. O fornecimento de probióticos via oral não afetou (P>0,05) o escore fecal, o desempenho dos animais (ganho de peso e consumo de concentrado). Como conclusão, a substituição de milho por polpa cítrica, melaço ou xarope de glicose no concentrado inicial não apresentou efeitos negativos relacionados à diarreia e não agravou os quadros de desidratação e acidose metabólica. O fornecimento de 2 gramas diários de probióticos de bactérias ruminais não resultou em melhorias no desempenho de bezerros desaleitados precocemente. / The objective of this study was to evaluate the occurrence of diarrhea and the consequences on animal metabolism of calves consuming starter feed containing coproducts such as citrus pulp, molasses and glucose syrup; or calves supplemented with direct-fed microbial (DFM). Two trials were performed to evaluate the effect of replacing corn by coproducts. In the first trial, 24 calves were divided into three treatments, and received starter feed containing increasing doses of citrus pulp replacing corn. In the second trial, 32 calves were divided into four treatments, and received starter feed containing glucose syrup and increasing doses of molasses replacing corn. In both experiments, animals were housed in individual hutches, received 4 L/d of milk replacer, divided into two meals and had free access to water and starter feed. After the diagnosis of the occurrence of diarrhea fecal score, clinical score, and the measurement of physiological parameters were evaluated during the following 24, 48 and 72 hours.Blood samples were taken for complete blood count (CBC), biochemical, electrolytes and gases analysis. The addition of coproducts in the starter feed had no effect (P>0.05) on fecal score, characteristics of the faeces and clinical signs of diarrheic animals. The plasma biochemical analysis (glucose, total protein, albumin, ?-hydroxybutyrate, urea nitrogen, lactate total D-and L-lactate) showed normal values and were negativelly affected (P>0.05) in response to the substitution of corn by coproducts in the stater feed for calves. No alterations (P>0.05) were noted in the erythrocyte and blood gases results, suggesting absence or low level of dehydration, and metabolic acidosis in animals. According to the white blood cell count (WBC), leukocytosis and neutrophilia were observed in most cases, suggesting infectious diarrhea and rejecting the possibility that the consumption of coproducts in the starter feed were the etiology of diarrhea cases. A third trial was performed to evaluate the overall performance of dairy calves supplemented with a probiotic containg ruminal bacterias. Twenty calves divided into two treatments (control and oral and daily supply of 2 grams of probiotic), animals were evaluated up to 10 weeks of age. Animals were housed in individual hutches, received 6 L/d of milk replacer, and had free access to water and starter feed. Weaning was done at the 6th week of age, as a meaning of causing stress in animals. Daily starter feed intake, weight gain, body development, and fecal score were evaluated. At 2nd, 4th, 6th, 8th and 10th weeks, blood samples were collected for biochemical analysis and WBC. The oral supply of probiotic had no effect (P>0.05) on fecal score or animal performance (weight gain and starter feed intake). In conclusion, the substitution of corn by citrus pulp, molasses or glucose syrup in the starter feed for dairy calves had no negative effects related to diarrhea or the agravation of dehydration and metabolic acidosis. The oral and daily supply of 2 grams of probiotics containg ruminal bacteria resulted in no improvements in performance of early-weaned dairy calves.

Les Escherichia coli enterohémorragiques (EHEC) sont responsables de maladies graves comme la colitehémorragique (CH), le syndrome hémolytique et urémique (SHU) ou le purpura thrombotiquethrombocytopénique (PTT). Les infections humaines sont principalement dues à la consommationd’aliments contaminés, en particulier la viande d’origine bovine, le lait ou les légumes. Le principalréservoir naturel des EHEC est le tractus gastro-intestinal (TGI) des bovins. Les fèces de bovins sont, parconséquent, responsables de la contamination de plusieurs types d’aliments mais également de ladissémination environnementale de ces bactéries pathogènes. En relation avec cette problématique, lesdeux objectifs de ce projet étaient (i) de développer une nouvelle méthode d’immuno-capture pouraméliorer l’isolement des principaux sérogroupes de EHEC impliqués dans les infections humaines; et (ii)de développer un nouveau DFM (direct fed microbial) utilisable chez les bovins pour diminuer laprévalence des EHEC chez les animaux. Cette thèse a permis le développement d’une méthoded’immuno-capture basée sur l’utilisation d’une microplaque à 96 puits, coatée avec des anticorpsspécifiquement dirigés contre E. coli O157 ou d’autres sérogroupes. Cette méthode, appelée immunomicroplatecapture (IMC) est efficace et facile d’utilisation pour l’isolement de souches d’E. coli O157 ;O26 ; O103 et O111 dans les produits alimentaires. L’IMC pourrait être une alternative à l’utilisation desbilles immuno-magnétiques qui sont classiquement utilisées pour la détection des EHEC dans lesproduits alimentaires, mais qui représentent une technique longue et fastidieuse lors de l’analysesimultanée de nombreux échantillons. La seconde partie de cette thèse a permis de sélectionner 5souches de bactéries lactiques qui présentent une activité antagoniste vis-à-vis d’E.coli O157 et d’autressérogroupes in vitro. La résistance de ces souches aux conditions du tractus gastro-intestinal (conditionsacides, présence de sels biliaires, présence de jus de rumen) a été évaluée in vitro. Leur innocuité a étévérifiée chez des souris Balb-C par l’administration de chacune des souches incorporées à la nourriture(109 cfu/g). Enfin, la lyophilisation des souches n’a pas affecté leur activité antagoniste in vitro. Lesrésultats obtenus dans les différents tests in vitro suggèrent que les 5 souches pourraientpotentiellement être utilisées comme DFM chez les bovins pour diminuer la colonisation de leur TGI parles EHEC et par conséquent diminuer le risque de contamination des aliments et le risque dedissémination environnementale. / Enterohemorrhagic E. coli (EHEC) are responsible for important diseases such as hemorrhagic colitis,hemolytic and uremic syndrome or thrombotic thrombocytopenic purpura. Human infections occurprincipally by consumption of contaminated food particularly beef meat, milk or vegetables. The mainnaturally reservoir of EHEC is the gastro-intestinal tract of cattle. Cattle feces are therefore responsiblefor contamination of various types of food but also environment dissemination of the pathogenicbacteria. Related to this problematic, the two objectives of this project were (i) to develop a newimmuno-capture method to improve the isolation of the main serogroups of EHEC involved in humaninfections in food; and (ii) to develop a new direct fed microbial usable in cattle to decrease prevalenceof EHEC in animals. This thesis allowed the development of an immuno-capture method based on theuse of 96-well microplates coated with specific antibody directed against E. coli O157 and otherserogroups. This method, called immuno-microplate capture (IMC) was efficient and user-friendly forthe isolation of E. coli O157; O26; O103 and O111 in foods. This could be an alternative to the use ofimmuno-magnetic beads which are currently used for the detection of EHEC in foods, but are timeconsumingand labor intensive when large number of samples is analyzed simultaneously. The secondpart of this thesis allowed the selection of 5 lactic acid bacteria strains which presented highantagonistic activity against E. coli O157 and other serogroups in vitro. Resistance of these strains togastro-intestinal conditions (acidic conditions, presence of bile salts and rumen fluid) was evaluated invitro. The safety of the 5 strains was checked in Balb-C mice by administration of each strain mixed infeed at 109 cfu/g. Finally, freeze-drying did not affect the antagonistic activity of the 5 strains, suggesteda possible large scale use of these strains. According to the various results obtained in vitro, the 5 strainscould potentially be used as DFM in cattle to decrease colonization of their gastro-intestinal tract byEHEC and consequently decrease the risk of food and environment contaminations.

O objetivo deste estudo foi avaliar a ocorrência de diarreia e suas consequências no metabolismo animal em bezerros consumindo concentrado inicial contendo coprodutos como polpa cítrica, melaço e xarope de glicose; ou bezerros suplementados com probiótico. Dois experimentos foram conduzidos para avaliar o efeito da substituição de milho por coprodutos. No primeiro experimento, 24 bezerros com idade média de 2 semanas, foram distribuídos em 3 tratamentos e receberam concentrado inicial contendo doses crescentes de polpa cítrica em substituição ao milho. No segundo experimento, 32 bezerros foram divididos em 4 tratamentos, recebendo concentrado inicial contendo xarope de glicose e doses crescentes de melaço em substituição ao milho. Em ambos os experimentos, os animais foram alojados em abrigos individuais, receberam 4 L de sucedâneo lácteo por dia, dividido em duas refeições e tiveram livre acesso à água e concentrado. Após o diagnóstico da ocorrência de diarreia, foram realizadas avaliações de escore fecal, escore clínico, além de medição dos parâmetros fisiológicos, nas seguintes 24, 48 e 72 horas. Foram colhidas amostras de sangue para realização de hemograma, análises bioquímicas, análises gasométricas e eletrolíticas. A adição de coprodutos no concentrado inicial não afetou (P>0,05) o escore fecal, as características das fezes e os sinais clínicos dos animais diarreicos. As análises plasmáticas bioquímicas (glicose, proteínas totais, albumina, ?-hidroxibutirato, nitrogênio ureico plasmático, lactato total, D- e L-lactato) apresentaram valores normais e não sofreram efeito negativo (P>0,05) em resposta da substituição de milho por coprodutos no concentrado. Não houve diferença entre os tratamentos (P>0,05) nas análises gasométricas e no eritrograma, com resultados indicando ausência ou baixo nível de acidose metabólica e desidratação nos animais. De acordo com o leucograma realizado, foi constatada leucocitose e neutrofilia na maioria dos casos, significando que a diarreia foi de origem infecciosa, descartando a possibilidade que o consumo de coprodutos no concentrado fosse a etiologia da diarreia. Um terceiro experimento foi realizado para avaliar o desempenho geral de bezerros suplementados com probíóticos contendo bactérias ruminais. Foram utilizados 20 bezerros divididos em 2 tratamentos (controle e fornecimento oral de 2 gramas de probiótico/dia), sendo os animais avaliados até a 10ª semana de vida. Os animais alojados em abrigos individuais, receberam 6 L de sucedâneo lácteo por dia, e tiveram livre acesso à água e concentrado. O desaleitamento foi realizado na 6ª semana de vida, de forma a causar uma situação de estresse nos animais. O consumo diário de concentrado, ganho de peso, desenvolvimento corporal e escore fecal foram avaliados. Nas semanas 2, 4, 6, 8 e 10 foram colhidas amostras de sangue para determinação de parâmetros bioquímicos e realização do hemograma. O fornecimento de probióticos via oral não afetou (P>0,05) o escore fecal, o desempenho dos animais (ganho de peso e consumo de concentrado). Como conclusão, a substituição de milho por polpa cítrica, melaço ou xarope de glicose no concentrado inicial não apresentou efeitos negativos relacionados à diarreia e não agravou os quadros de desidratação e acidose metabólica. O fornecimento de 2 gramas diários de probióticos de bactérias ruminais não resultou em melhorias no desempenho de bezerros desaleitados precocemente. / The objective of this study was to evaluate the occurrence of diarrhea and the consequences on animal metabolism of calves consuming starter feed containing coproducts such as citrus pulp, molasses and glucose syrup; or calves supplemented with direct-fed microbial (DFM). Two trials were performed to evaluate the effect of replacing corn by coproducts. In the first trial, 24 calves were divided into three treatments, and received starter feed containing increasing doses of citrus pulp replacing corn. In the second trial, 32 calves were divided into four treatments, and received starter feed containing glucose syrup and increasing doses of molasses replacing corn. In both experiments, animals were housed in individual hutches, received 4 L/d of milk replacer, divided into two meals and had free access to water and starter feed. After the diagnosis of the occurrence of diarrhea fecal score, clinical score, and the measurement of physiological parameters were evaluated during the following 24, 48 and 72 hours.Blood samples were taken for complete blood count (CBC), biochemical, electrolytes and gases analysis. The addition of coproducts in the starter feed had no effect (P>0.05) on fecal score, characteristics of the faeces and clinical signs of diarrheic animals. The plasma biochemical analysis (glucose, total protein, albumin, ?-hydroxybutyrate, urea nitrogen, lactate total D-and L-lactate) showed normal values and were negativelly affected (P>0.05) in response to the substitution of corn by coproducts in the stater feed for calves. No alterations (P>0.05) were noted in the erythrocyte and blood gases results, suggesting absence or low level of dehydration, and metabolic acidosis in animals. According to the white blood cell count (WBC), leukocytosis and neutrophilia were observed in most cases, suggesting infectious diarrhea and rejecting the possibility that the consumption of coproducts in the starter feed were the etiology of diarrhea cases. A third trial was performed to evaluate the overall performance of dairy calves supplemented with a probiotic containg ruminal bacterias. Twenty calves divided into two treatments (control and oral and daily supply of 2 grams of probiotic), animals were evaluated up to 10 weeks of age. Animals were housed in individual hutches, received 6 L/d of milk replacer, and had free access to water and starter feed. Weaning was done at the 6th week of age, as a meaning of causing stress in animals. Daily starter feed intake, weight gain, body development, and fecal score were evaluated. At 2nd, 4th, 6th, 8th and 10th weeks, blood samples were collected for biochemical analysis and WBC. The oral supply of probiotic had no effect (P>0.05) on fecal score or animal performance (weight gain and starter feed intake). In conclusion, the substitution of corn by citrus pulp, molasses or glucose syrup in the starter feed for dairy calves had no negative effects related to diarrhea or the agravation of dehydration and metabolic acidosis. The oral and daily supply of 2 grams of probiotics containg ruminal bacteria resulted in no improvements in performance of early-weaned dairy calves.

The aim of this study was to evaluate the effects of M. elsdenii (Me) dosing on dairy heifer performance. A secondary set of data (feed intake, heifers birth weights, age and Weight at insemination, and first lactation milk performance) of heifers (dosed and not dosed with Me) was obtained from the dairy herd of the Agricultural Research Council – Animal Production. Data were arranged in a complete randomised design and analysed as repeated measures. Milk, pre-weaning starter and metabolised energy intake did not differ between the control and the Me groups. Post-weaning starter feed intake was higher (p=0.03) for Me fed heifers than control heifers. The post-weaning metabolisable energy intake was also higher (p=0.03) for heifer fed Me than control heifers. The average daily weight gain of heifers dosed with Me was higher during the pre-weaning period (0.66 kg/day; p=0.04) and after weaning (1.12 kg/day; p=0.03) compared to control (0.60 and 0.65 kg/day, respectively). At 42 and 70 days old, the BW of Me-heifers was greater (75.8 ± 2.6 and 91.2 ± 4.6 kg) than control heifers (61.9 ± 2.6 and 77.2 ± 4.6 kg) (p<0.05). There was no difference (P>0.05) in BW at insemination, number of insemination and milk yield between the two groups of cows (p>0.05). Early feeding of Me to heifers in the present study positively affect heifer growth during and early after milk feeding period, confirming previous report. Animal weight at puberty and the subsequent milk production were not influenced by feeding Me. It is possible that Me did not survive long after weaning to continue to express its influence on animal performance. / Agriculture and  Animal Health / M. Sc. (Agriculture)