Effect of laidlomycin propionate on beef bull growth performance and reproductive development

The effects of laidlomycin. propionate (LP) on, beef bull growth performanc e and sexual development were determined in, all. 84 day study. Forty embry o transfer Angus bulls were fed three complete diets containing LP levels o f either 0, 10 or 20 g/t. Bulls were fed daily using electronic feeders to obtain individual feed intake. Full weight and scrotal circumference (SC) w ere evaluated at 28 day intervals, Breeding soundness examinations were con ducted to characterize semen. Muscle mass and body fat were estimated using real-time ultrasonography. Laidlomycin propionate did not influence daily gain, dry matter intake, feed efficiency, subcutaneous or intramuscular fat deposition, but Longissimmus muscle deposition was enhanced. Among treatme nts, bulls had similar (P>0.05) SC measurements and no detrimental effects on semen quality or sperm morphology were observed. Supplementing growing b ulls with laidlomycin propionate for improved performance did not detriment ally affect sexual development.