The effect of rearing environment on sexual behavior of young beef bulls.

Fifty-eight Polled Hereford bull calves were weaned at an average age of 196 d. They were penned individually after weaning and contact was limited to fenceline exposure to bulls in adjacent pens, except when grouped for weighing every 28 d. Six months after weaning they were allotted to one of the following 10-wk rearing treatments: 1) individually penned; 2) individually penned, but exposed to a heifer in estrus for 30 min every 2 wk; 3) group penned; 4) group penned, but each bull exposed to a heifer in estrus for 30 min every 2 wk. The week after allotment was designated wk 0. All 58 bulls, penned together after wk 12, had single-bull mating tests during wk 10, 22 and 32 and multi-bull mating tests during wk 12, 24 and 34. Mean serving capacity and mean serving efficiency were both greater (P less than .05) for individually-penned bulls than for group-penned bulls during the first single-bull and the first multi-bull mating test. No significant serving-capacity differences were present in subsequent single-bull or multi-bull mating tests, but serving efficiency was greater (P less than .05) for group-penned bulls in all subsequent tests, except the last multi-bull mating test. Mean serving capacity was greater (P less than .05), as was mean serving efficiency (P less than .01), for bulls in single-bull mating tests than for those in multi-bull tests. Exposure to heifers during rearing did not affect libido or mating ability.(ABSTRACT TRUNCATED AT 250 WORDS)