Caracterização de parâmetros bioquímicos e histológicos do rúmen de bezerros holandeses mestiços pré e pós desmame

• Autor(a) principal: Lopes, Déborah Romaskevis Gomes
• Data de Publicação: 2014
• Tipo de documento: Dissertação
• Idioma: por
• Título da fonte: LOCUS Repositório Institucional da UFV
• Texto Completo: http://locus.ufv.br/handle/123456789/5374
• topic: Bezerro - Alimentação; Rúmen; Fermentação ruminal; Calf - Food; Rumen; Ruminal fermentation; CNPQ::CIENCIAS AGRARIAS::ZOOTECNIA::NUTRICAO E ALIMENTACAO ANIMAL

At birth, ruminant animals have a non-functional rumen. The maturation of the forestomachs involves colonization by anaerobic microorganisms, establishment of ruminal fermentation, increase in volume, muscle strengthening and papillae growth (which increases absorptive area). Studies suggest that the introduction of solid feeds in the diet aids the anatomical and physiological development of the rumen. In this work, Holstein crossbred calves fed different levels of milk (2, 4, 6 and 8 liters/day) and concentrate ad libitum during the breast-feeding period were used to evaluate the weight gain, dry matter intake and ammonia and volatile fatty acids (VFA) concentration in the rumen. Additionally, the thickness of the epithelium, conjunctive, muscle tissues, and height and density of the rumen papillae at weaning and 30 days after weaning was also determined. The increase in average daily gain (ADG) was associated with increased daily intake of total dry matter (TDMI). The daily dry matter intake of concentrate (DMIc) and the daily milk intake of animals sacrificed at weaning showed a high quadratic correlation (r = 0.83), whereas the maximum DMIc (0.27 kg/d) was observed when the animals were fed four liters of milk daily. The TDMI after weaning did not differ (P > 0.05) for animals fed 4, 6 and 8 liters of milk/day during the breast-feeding period. The concentration of volatile fatty acids (VFAs) in the rumen increased (P < 0.05) with animal age, but the proportion of acetate, propionate and butyrate (4.5 : 3: 1) did not differ (P> 0.05) at weaning and 30 days after weaning. Animals with larger ADG sacrificed at weaning had lower proportions of propionate in the rumen. The mean ammonia concentration in the rumen of animals sacrificed at weaning was 2.5 times larger (P < 0.05) than that observed in animals sacrificed three days old and 30 days after the introduction of hay in the diet. The ammonia concentration in the rumen increased with TDMI and was related to a greater ADG of the animals. The thickness of the epithelial and conjunctive tissue did not differ (P > 0.1) with age, whereas the height of the papillae increased (P <0.1) and the density of the papillae reduced (P < 0.1). The ADG of the animals sacrificed at weaning increased with the reduction of papillae density (enlargement of the absorption surface of the rumen epithelium). The increase in DMIc of animals sacrificed at weaning did not influence the thickness of the muscle tissue. However, it was associated with increased papillae height. The propionate concentration and papillae height of the ventral sac of the rumen of animals sacrificed at weaning showed a quadratic correlation (r = 0.82), and higher papillae were observed when the propionate concentration was about 30 mmol/l. These results indicate that different levels of milk intake during the breast-feeding period influence the intake of concentrate, which reflected in the development of the rumen papillae. In addition, the ability to consume concentrate feeds increased with age, making more substrates available for rumen microbial fermentation.