Sexual performance of rams reared with or without females after weaning

The objective of this study was to determine the effect of postweaning exposure to females on the subsequent sexual performance of young rams. Twenty-five crossbred rams were reared in a group with ovariectomized females from 4.5 to 9 mo of age. Ewes were brought into estrus every 2 wk during this period. A companion group of 23 crossbred rams was not exposed to females following weaning. Four 30-min sexual performance tests were administered at 10 mo of age. Rams reared with males and females (RMF) exhibited more mounts (P less than .001) and more ejaculations (P less than .002) than rams reared only with males (RM). The frequency of successful matings by the latter group did not increase with experience. Nine rams were sexually inactive in the sexual performance tests. Follow-up tests revealed that two of the RMF rams and one RM ram developed and maintained a sexual preference for males. The six remaining rams eventually mated with females when tested in familiar pens and subsequently exhibited normal levels of sexual performance even when tested in an unfamiliar enclosure. Exposure to ewes during the postweaning prepubertal period enhanced sexual performance. However, early exposure to females did not ensure that all males developed sexual preferences for females. The environmental context in which sexual performance tests are administered may inhibit the expression of heterosexual behavior in a small percentage of animals. After heterosexual behavior was expressed, the rams continued to show normal levels of sexual performance.(ABSTRACT TRUNCATED AT 250 WORDS)