Author
 |
Stellflug, John |
|
BERARDINELLI, J. - MONTANA STATE UNIV. |
|
Submitted to: Journal of Animal Science
Publication Type: Peer Reviewed Journal Publication Acceptance Date: 6/12/2002 Publication Date: 10/12/2002 Citation: Stellflug, J.N., Berardinelli, J.G. Ram mating behavior after long-term selection for reproductive rate in Rambouillet ewes. Journal of Animal Science. 2002. v. 80. p. 2588-2593. Interpretive Summary: Mating behavior is heritable in several species, but it is not known if selection for ewe traits affect ram mating behavior. Our objectives were to determine if divergent (high vs low) selection of a female trait (lambs born) affects mating behavior of male offspring when trained to service an artificial vagina in a less than natural setting or during serving capacity tests in simulated natural mating conditions. For Exp. 1, five, 30-min observations were conducted to assess mating behavior on 29, 22-mo-old rams being trained to service an artificial vagina. In Exp. 2, rams were evaluated by exposing each 22-to 24-mo-old ram (n = 48) to three unrestrained estrous ewes for 18, 30-min tests. Each ram that had not mounted or ejaculated in 18 tests was observed in a 30-min sexual preference test with access to restrained rams and estrous ewes to identify male-oriented(homosexual)rams. In Exp. 1, more rams mounted (73 vs 36%) and ejaculated (67 vs 29%)in high than in low ewe selection line rams, respectively. In Exp. 2, there was no difference in rams mounting (92 vs 78%) and ejaculating (88 vs 74%) between high and low ewe selection line rams, respectively. We identified one male-oriented ram. In Exp. 2, six tests were required for 95% reliability in sexual performance scores. Our results indicate that long-term selection of ewes for lambs born did not alter ram performance in serving capacity tests in simulated natural mating conditions or affect incidence of male-oriented rams. Mating behavior when training to service an artificial vagina was decreased in low compared to high ewe selection line rams. Thus, selection for lambs born did not alter mating behavior of male offspring, and test number and conditions can affect the outcome. Technical Abstract: Mating behavior is heritable in several species, but it is not known if selection for ewe traits affect ram mating behavior. Our objectives were to determine if divergent (high vs low) selection of a female trait (lambs born) affects mating behavior of male offspring when trained to service an artificial vagina (AV) in a less than natural setting or during serving capacity tests in simulated natural mating conditions. For Exp. 1, five, 30-min observations were conducted to assess mating behavior on 29, 22 mo-old rams being trained to service an AV. In Exp. 1, rams mounting (73 vs 36%) and ejaculating (67 vs 29%) differed (P < 0.05) between high and low ewe selection line rams, respectively. In Exp. 2, rams were evaluated by exposing each 22 to 24 mo-old ram (n = 48) to three unrestrained estrous ewes for 18, 30-min tests. Each ram that had not mounted or ejaculated in 18 tests was observed in a test with access to restrained rams and estrous ewes to identify male-oriented rams. In Exp. 2, there was no difference (P > 0.2) in rams mounting (92 vs 78%) and ejaculating (88 vs 74%) between high and low ewe selection line rams, respectively. There was no difference (P > 0.33) between high and low line rams for mounts or ejaculations for 18 tests. We identified one male-oriented ram. In Exp. 2, six tests were required for 95% reliability in sexual performance scores. Our results indicate that long-term selection of ewes for lambs born did not alter (P > 0.1)ram performance in serving capacity tests in simulated natural mating conditions or affect incidence of male-oriented rams. Mating behavior when training to service an AV was decreased in low compared to high line rams. Thus, ewe selection for lambs born did not alter mating behavior of male offspring, and test number and conditions can affect the outcome. |
