Beef breed response to dietary energy level: in vivo digestibility
1989
Prichard, D.L. | Essig, H.W. | Teare, I.D.
Six steer calves/breed representing Bos taurus [Hereford and Charolais] and crosses or breeds with increasing amounts of Bos indicus [Three Breed Cross (TBC) [50% Hereford, 25% Angus, 25% Brahman], Santa Gertrudis, Barzona, Brahman] were used to investigate breed (in vivo) differences in utilization of diets varying in energy and roughage content. All steer calves were approximately the same age (10 mo) and weight (264 kg) at the beginning of the study. Diets were formulated on a constant calorie to protein ratio of 220 kcal of digestible energy (DE) per percentage unit of protein. The caloric density of the high medium, and low diets were 3086, 2756, and 2427 kcal/kg. Breed of steers did not significantly influence apparent digestible energy, digestible dry matter (DDM), energy digestion coefficient (EDC) or nitrogen retention (N Ret.) of diets. No significant breed-by-diet interaction was observed. Apparent digestibility energy values of steers fed the high energy diet were higher (P > 0.05) than those of steers for the medium or low energy diets. Feces excreted by Charolais and Brahman steers was dryer (P < 0.05) than feces from Barzona, Hereford, Santa Gertrudis, and TBC steers. Fecal dry matter percentages were not influenced by diet.
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