Effect of early fenceline exposure to estrous ewes on the sexual performance of yearling rams

• Published in: Applied animal behaviour science Vol. 64; no. 4; pp. 241 - 247
• Main Authors: Price, Edward O, Borgwardt, Reid, Dally, Martin R
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01-08-1999
• Subjects: ejaculation; libido; Mating; mating ability; mating behavior; prediction; rams; Reproduction; Sexual behavior; Sheep; Mating; Sheep; Reproduction; Sexual behavior
• ISSN: 0168-1591; 1872-9045
• DOI: 10.1016/S0168-1591(99)00040-4

Previous research has demonstrated that early heterosexual (mating) experience improves the sexual performance of yearling rams. The present study examines the effect of early
fenceline (FL) contact of young ram lambs with estrous females on their sexual performance as yearlings. A total of 104 rams, 7–8 months of age, were given either no contact (NC), direct contact (DC) or FL exposure to estrous ewes during a 3-week period in the fall breeding season. When initially tested for sexual performance as yearling rams at 18–19 months, 8 of 21 (38%) FL rams exhibited no sexual interest in estrous females (did not court or mount females), a result that was intermediate to and not significantly different from (
P>0.05) the incidence of sexual disinterest exhibited by NC (59%) and DC rams (15%). The difference between NC and DC rams was significant (
P<0.002). In addition, 12 of 21 (57%) yearling FL rams initially mounted estrous ewes, a result that was intermediate to and not significantly different from (
P>0.05) the incidence of mounting by NC and DC males (41% vs. 85%, respectively). Again, NC and DC rams differed from one another (
P<0.002). Treatment did not affect frequencies of mounting with and without ejaculation by the sexually active rams (
P=0.11 and 0.36, respectively). FL rams that were sexually inactive in year 2 spent less time (
P<0.02) in year 1 within a body length of the fence separating them from the ewes than FL rams that were sexually active in year 2. FL proximity scores in year 1 were positively correlated (
r
s=0.49;
P<0.05) with ejaculation frequencies in year 2. It was concluded that early FL contact with ewes only partially substitutes for direct heterosexual (mating) experience in enhancing the sexual performance of yearling rams. Also, measures of FL proximity to estrous ewes can serve as an aid in predicting relative levels of sexual performance in rams.