Degradabilidade ruminal da cama de frango e do feno de capim coast-cross e avaliação de modelos matemáticos para estimativa da taxa de passagem de partículas

O experimento foi realizado para avaliar a cinética de degradação ruminal da matéria seca (MS), proteína bruta (PB) e fibra em detergente neutro (FDN) e os diferentes modelos para estimativa da taxa de passagem, em novilhos recebendo dietas com 15,0% de cama de frango, associada a dois níveis de suplemento à base de flora ruminal liofilizada de bovinos adultos (0 e 10 g/animal•dia). Quatro novilhos fistulados no rúmen e abomaso foram distribuídos em delineamento inteiramente casualizado. A taxa de passagem foi determinada por intermédio da técnica do cromo complexado à parede celular do feno de coast-cross, como indicador, e a degradabilidade, por intermédio da técnica do saco de náilon. Os modelos matemáticos foram avaliados por meio do estudo dos desvios padronizados e do número de corridas de sinal. A ingestão diária de 10 g do suplemento, por animal, não influiu na taxa de passagem das partículas e na degradabilidade ruminal. A cinética de passagem apresentou comportamento tempo-dependente. O modelo Dhanoa mostrou-se mais eficiente na determinação dos parâmetros relativos à taxa de passagem.The experiment was conducted to evaluate the dry matter (DM), crude protein (CP) and neutral detergent fiber (NDF) degradation kinetics and different models to estimate the passage rate in steers fed diets with 15.0% of broiler litter associated to two levels of a supplement based on bovine lyophilized ruminal microbiota (0 and 10 g/animal•day). Four steers with ruminal and abomasal fistulae were allotted to a completely randomized experiment. The passage rate was determined using chromium complexed to the cellular wall of the coast cross hay, as a marker, and the degradability, by means of the nylon bag technique. The mathematical models were evaluated by means of standardized deviations and of the number run signals. The daily intake of 10 g of the supplement per animal did not affect the passage rate and ruminal degradation. The passage kinetics had a time-dependent behavior. The Dhanoa model showed to be the most efficient in the determination of the parameters related to the passage rate

The value of trace minerals in a fattening ration.

This is the fourth in a series of experiments conducted to determine the value of trace minerals in a typical fattening ration. Three previous experiments, similar to this one, were reported in Kansas Agr. Exp. Sta. Cirs. 297, 308 and 335. Chemical analyses of feeds commonly used in cattle rations in this area show there is no deficiency in any of the trace minerals: cobalt, copper, iodine, iron, manganese and zinc. It is possible the minerals may not be adequately balanced or available to the animal at all times. The objective of this test is to determine if trace minerals, when fed at a commonly used level, will influence rate of gain and feed efficiency