Consumo de nutrientes e parâmetros ruminais de vacas alimentadas com diferentes níveis de energia na dieta

Abstract

RESUMOAvaliou-se a influência de níveis de concentrado na dieta de bovinos. Utilizaram-se quatro vacas fistuladas no rúmen, distribuídas em quadrado latino 4x4, sobre o consumo, pH ruminal e nitrogênio amoniacal (N-NH 3 ). Foi utilizada a silagem de milho, como volumoso, e concentrado, à base de milho, sorgo, farelo de soja, casca de soja, ureia e gordura protegida. As dietas foram isoproteicas com 18,6% de proteína bruta, utilizando valores crescentes de extrato etéreo (5,7; 6,6; 7,5 e 8,4%) para os níveis de concentrado de 30; 40; 50 e 60%. Os valores médios de pH ruminal foram 6,71; 6,64; 6,63; 6,69 e as concentrações médias de N-NH 3 de 37,40; 39,62; 35,59 e 34,13mg/100mL de líquido ruminal. O tratamento com 7,5% de extrato etéreo apresentou média de consumo de fibra detergente neutro mais alto que os demais tratamentos, com máximo consumo de matéria seca estimado em 10,47kg/dia. Dietas com gordura protegida não interferiram no ambiente ruminal, até níveis de 8,4% de extrato etéreo, apresentando melhor eficiência com relação ao consumo de 55% de concentrado.Palavras-chave: vaca de leite, rúmen, extrato etéreo, nível de concentrado, pH ruminal, nitrogênio amoniacal ABSTRACT The influence of concentrate levels in the diet of cattle on intake, rumen pH, and ammonia nitrogen (NH3-N) using four cows fistulated in the rumen and distributed in 4x4Latin square was evaluated. Corn silage was used as roughage and concentrate was maize, sorghum, soybean hulls, soybean rules, urea, and protected fat. Diets were isonitrogenous with 18.6% crude protein, using increasing amounts of ether extract (5.7, 6.6, 7.5, and 8.4%) to the levels of concentrate, 30, 40, 50 and 60%. The average values of rumen pH were 6.71, 6.64, 6.63, 39.62, 35.59, and 34.13mg

Ruminal parameters of bovines fed diets based on sugar cane with doses of calcium hydroxide

“…Goularte et al (2010) found average concentrations of N-NH 3 of 37.40, 39.62, 35.59 and 34.13 mg/100 mL of rumen fluid for concentrate levels of 30, 40, 50 and 60%, respectively. It is noteworthy that high levels of N-NH 3 can mean bigger losses of nitrogen in the system, since, in order for there to be synthesis microbial protein and, consequently, use of N-NH 3 , there should be availability of carbon skeletons in synchrony with degradation protein in the rumen, which does not occur in diets with reduced starch and non-structural carbohydrates and/or sources of energy from fat, which should lead to loss of energy in the form of ATP, for processing into urea by the liver to urinary excretion, which probably did not occur in the present experiment, due to the lower concentrations of N-NH 3 .…”