Ram sexual preferences and estrous behavior expression in ewes with different reproductive status

Abstract

: The hypothesis was that the level of sexual experience and reproductive status of ewes affect the time that rams dedicate to courtship. Ewes (n = 40) were separated into four groups according to their reproductive status: maiden, empty, under continuous and restricted suckling ewes. Rams (n = 8) were separated into four groups according to their sexual experience: experienced-I and -II and inexperienced-I and -II. Each group of ewes was exposed at the same time to a different group of rams at 10–12 h intervals for 22 days, an injection of prostaglandin was given to ewes at the end of this period. The response variables were the time that each group of rams spent courting each group of ewes during the first 22 days of the experiment and the number of ewes from each group that showed estrous behavior during and after the 22 days of the experiment. Sexually inexperienced rams spent more time courting maiden ewes than any other group of ewes (p ≤ 0.05) (39.59 ± 3.01, 29.41 ± 3.01, 26.31 ± 3.01 and 23.36 ± 3.01 minutes for the maiden, continuous, restricted and empty groups, respectively). Experienced rams dedicated more time to courting the group of empty ewes (p ≤ 0.05) (13.55 ± 3.01, 17.68 ± 3.01, 14.9 ± 3.01 and 20.05 ± 3.01 minutes for the maiden, continuous, restricted and empty groups, respectively). Expression of estrous behavior was affected (p ≤ 0.05) by the reproductive status of the ewes during the first 22 days of the experiment; the higher difference was in favor of ewes from the empty group. In addition, a higher display of estrous behavior was observed after prostaglandin injection (p ≤ 0.05). In conclusion, the level of sexual experience and the reproductive status of the ewes affects the time that rams spend in courtship.