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Doctoral Thesis
DOI
https://doi.org/10.11606/T.11.2020.tde-12082020-160723
Document
Author
Full name
Gercino Ferreira Virginio Júnior
E-mail
Institute/School/College
Knowledge Area
Date of Defense
Published
Piracicaba, 2020
Supervisor
Committee
Bittar, Carla Maris Machado (President)
Gomes, Viviani
Mantovani, Hilario Cuquetto
Title in Portuguese
A composição de diferentes dietas e a idade de bezerros leiteiros afetam o microbioma ruminal e intestinal
Keywords in Portuguese
Diversidade microbiana
Genômica
Microbiota fecal
Saúde intestinal
Abstract in Portuguese
Em teoria, bezerros leiteiros nascem com o trato gastrintestinal estéril e durante o nascimento, inicia-se a colonização microbiana. A partir desse momento, a dieta torna-se um importante fator de manutenção da população microbiana, além de servir de substrato para a mesma. No entanto, pouco se sabe como diferentes dietas podem modificar o microbioma gastrintestinal em bezerros leiteiros durante a fase de aleitamento e desaleitamento. Com base nisso, dois estudos foram realizados. O primeiro estudou avaliou diferentes níveis e fontes de FDN no concentrado inicial. Foram utilizados 18 bezerros Holandeses, alimentados com um dos três tratamentos: 22FDN - concentrado convencional contendo 22% de FDN; 31FDN - concentrado com 31% de FDN, substituindo parte do milho por casca de soja; e 22Feno - concentrado convencional com 22% de FDN e feno coast cross a vontade. Foram alojados em gaiolas suspensas, sem cama até a 8ª semana de vida, desaleitados e depois alojados em abrigos do tipo tropical até a 10ª semana de vida. Foram avaliados o microbioma ruminal, nas semanas 2, 4, 6, 8 e 10, e o microbioma fecal nas semanas 0, 1, 2, 4, 8 e 10. O microbioma ruminal não mostrou diferenças em função da dieta, idade ou interação de ambos os fatores. O microbioma fecal foi afetado tanto pela idade quanto pela dieta. A inclusão de feno na dieta pode promover maior diversidade microbiana fecal. O segundo estudou avaliou diferentes dietas líquidas durante o aleitamento. Foram utilizados 15 bezerros Holandeses alimentados com uma das três dietas líquidas: leite integral, sucedâneo lácteo, e leite integral acidificado a pH 4,5 com ácido fórmico. Os animais foram alojados em abrigos tropicais, recebendo 6 litros de dieta líquida por dia, sendo desaleitados a partir da 8ª semana de vida, e alojados em abrigo coletivo a partir do desaleitamento. O microbioma fecal foi avaliado nas semanas 0, 1, 2, 4, 8 e 10. A diversidade microbiana foi afetada pela idade e dieta. A diversidade foi crescente a partir da semana 1. O leite promoveu maior diversidade microbiana fecal em comparação as demais dietas, além de promover o crescimento de bacterias benéficas e comensais no instetino. No entanto, após os animais deixarem de receber as dietas líquidas e serem alojados em conjunto, o microbioma fecal desses animais convergiu para uma maior similaridade.
Title in English
The composition of different diets and the age of dairy calves affect the ruminal and intestinal microbiome
Keywords in English
Fecal microbiota
Intestinal health
Microbial diversity; Genomics
Abstract in English
In theory, dairy calves are born with a sterile gastrointestinal tract and at birth, microbial colonization begins. From that moment on, the diet becomes an important factor for maintaining the microbial population, in addition to serving as a substrate for growth. However, it is necessary to know how different diets can modify the gastrointestinal microbiome in dairy calves during the pre-weaning and weaning phase. Based on that, two studies were performed. The first study evaluated different levels and sources of NDF in the starter concentrate. Eighteen Holstein calves were used, fed with one of three treatments: 22NDF - conventional starter concentrate containing 22% NDF; 31NDF - starter concentrated with 31% NDF, replacing part of the corn with soybean hull; and 22Hay - conventional concentrate with 22% NDF and coast cross hay at will. The animals were housed in suspended not-bedded cages, until the 8th week of life, weaned and then housed in tropical shelters until the 10th week of life. The rumen microbiome was evaluated at weeks 2, 4, 6, 8 and 10, and the fecal microbiome at weeks 0, 1, 2, 4, 8, and 10. The ruminal microbiome had no differences depending on diet, age, or interaction of both factors. The fecal microbiome was affected by both age and diet. The supply of hay in the diet can promote greater fecal microbial diversity. The second studied evaluated different liquid diets during the pre-weaning phase. Fifteen Holstein calves fed one of the three liquid diets were used: whole milk, milk replacer, and whole milk acidified to pH 4.5 with formic acid. The animals were housed in tropical shelters, receiving 6 liters of liquid diet per day, being weaned after the 8th week of life, and housed in a collective shelter from weaning. The fecal microbiome was evaluated at weeks 0, 1, 2, 4, 8, and 10. Microbial diversity was affected by age and diet. Diversity increased from week 1. Whole milk promoted greater fecal microbial diversity compared to other diets, in addition to promoting the growth of beneficial and commensal bacteria in the feces. However, after the animals stopped receiving liquid diets and were housed together, the fecal microbiome of these animals converged towards greater similarity.
 
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Publishing Date
2020-08-13
 
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