Impacts of diet inversion on voluntary intake, digesta and fecal composition, and bacterial community composition in rumen of cattle fed tropical forage-based diets

• Ano de defesa: 2015
• Autor(a) principal: Machado, Marcelo Grossi
• Tipo de documento: Dissertação
• Tipo de acesso: Acesso aberto
• Idioma: eng
• Instituição de defesa: Universidade Federal de Viçosa
• Palavras-chave em Português: Bovino - Alimentação e rações; Digestão; Rúmem; Fermentação; Fezes - Análise; Ciências Agrárias; Zootecnia; Avaliação de Alimentos para Animais
• Link de acesso: http://www.locus.ufv.br/handle/123456789/7310

The objective of this study was to evaluate the impact of the diet inversion on voluntary intake, ruminal digesta and feces composition, ruminal fermentation, and bacterial community composition in cattle fed tropical forage-based diest and to establish the minimal length of the adaptation period that could be applied to changeover or crossover design protocols. Twelve rumen-cannulated crossbreed (B. taurus × B. indicus) bovines were used in this experiment (four young bulls, four steers, and four heifers). The experiment lasted 60 d and two diet inversions were done at d 21 and d 41. Four diet sequences were evaluated (one animal of each category per sequence): sugarcane-corn silage-sugarcane, corn silage-sugarcane-corn silage, high-low-high concentrate diets, and low-high-low concentrate diets. All diets were adjusted to 110 g crude protein per kg of dry matter by using urea. Four group of variables were evaluated along experimental days: voluntary intake characteristics, fecal excretion and composition, ruminal digesta compostion, and ruminal fermentation profile. The pattern of the groups along time was interpreted through a non-hierarchical clustering procedure. The diversity of the liquid-associated rumen bacterial community was evaluated by PCR-DGGE in the young bulls from 6 days before to 20 days after the second diet inversion. The pattern of microbial diversity was evaluated through a clustering procedure using the unweight pair group method with arithmetic mean. Stabilization of the voluntary intake, ruminal digesta, fecal excretion and composition, and rumen fermentation profile was achieved within 9-13, 9- 14, 6-13, and 4-11 days after diet inversion, respectively. The bacterial community in the liquid phase stabilized within 3-9 days after diet inversion. The maximum required adaptation period among all characteristics must be chosen to assure the utilization of a robust experimental protocol. From the results of this experiment, among all obtained times to adapt intake, fecal and digesta composition, and ruminal fermentation and microbial diversity, a 14- days adaptation period is recommended for changeover and crossover experiments with cattle fed tropical forage-based diets.