Stilbestrol Responses in Lambs Fed Rations Differing in Calorie to Protein Ratios

Abstract

Eighteen rations differing with respect to amount of protein, stilbestrol, and net energy were fed in a 3×3s×2 factorially designed experiment to 144 growing and fattening lambs. Individual feed records and liveweight gains of the lambs were recorded, and at the termination of the feeding period the animals were slaughtered and detailed physical and chemical measurements were made upon the carcasses together with measurements of certain blood constituents and selected endocrine glands. Stilbestrol stimulated liveweight gains and improved feed conversion in most instances. It gave somewhat more stimulation with high energy and high protein rations than with low energy and low protein rations. Carcass fatness was unaltered by stilbestrol feeding when the Calorie-protein ratio of the rations was near 56. With rations of higher Calorie-protein ratios, stilbestrol increased carcass fatness and with rations of lower ratios it resulted in leaner carcasses with less fat. Dressing percent was increased slightly by the high protein rations, decreased slightly by stilbestrol, and increased substantially by the high energy rations. In general, the lambs fed the high energy and the high protein rations had higher live and carcass grades. Stilbestrol did not affect live or carcass grades. The weights of the anterior pituitary, kidneys, liver and secondary sex glands were all increased by stilbestrol feeding. The high energy rations produced lambs with heavier kidneys and livers. The weights of the thyroids, kidneys and liver were increased as the level of protein was increased. Serum glucose was significantly increased by stilbestrol and by the high energy rations, and reduced by the high protein rations. Serum amino nitrogen was not affected appreciably by the various treatments; however, it was somewhat lower when stilbestrol was fed and higher when the high protein rations were fed. Copyright © . .