Effects of trenbolone acetate and resorcylic acid lactone on protein metabolism and growth in steers

Abstract

ABSTRACTTwenty-four castrate male cattle were used in two nutritional balance and slaughter experiments to measure the effects of two implantations with 300 mg trenbolone acetate and 36 mg resorcylic acid lactone over the live-weight range 250 to 400 kg. Control and implanted animals were pair-fed barley-based diets of differing protein concentration in the first experiment and the lower protein diet at two levels of feeding in the second experiment.Daily live-weight gain and nitrogen retention were significantly increased by implantation in both experiments. The carcasses of implanted animals contained significantly more lean meat and a higher proportion of meat in the forequarter. The edible portion of these carcasses contained significantly more protein and water and less fat.Live-weight gain and carcass composition were not influenced by dietary protein intake. Increased feeding level improved live-weight gain, suggesting that a higher metabolizable energy intake would give an increased response to implantation.