Sexual behavior of donkey jacks: Influence of ejaculatory frequency and season

Abstract

The courtship of 5 jacks was evaluated weekly for 12 mo. The characteristics of sexual behavior were recorded before the collection of 2 ejaculates, at 4-h intervals, into an artificial vagina in the presence of a female in either natural or induced estrus. The maximum time given to the jack to perform the ejaculatory mount was 1h. If the jacks did not ejaculate, another attempt was made the following week. At the time of collection, the male and female remained free in a paddock (20 m 2). The data presented in this study is based on results in which the first and second ejaculates occurred successively. Statistical analysis was done by a 2 × 2 factorial design in randomized blocks. The mean ± SEM of sexual behavior characteristics for the first and second ejaculate were, respectively: time until first mount = 0.7 ± 0.2 and 0.9 ± 0.2 min; time until first erection = 11.9 ± 1.1 and 11.6 ± 1.1 min; time until ejaculation = 15.0 ± 1.2 and 13.6 ± 1.2 min; frequency of partial exposure of penis = 3.4 ± 0.4 and 3.2 ± 0.4; frequency of total exposure of penis = 1.0 + 0.2 and 1.1 ± 0.2; frequency of flehmen responses = 6.6 ± 0.5 and 4.6 ±0.5; frequency of erections = 1.3 ± 0.1 and 1.2 ± 0.1; frequency of retreats away from the female = 1.8 ± 0.2 and 1.0 ± 0.2; frequency of mounts with erection but without ejaculation = 0.3 ± 0.1 and 0.1 ± 0.1; frequency of mounts without erection = 2.0 ±0.1 and 1.2 ± 0.1 ; and frequency of pelvic copulatory movements = 4.8 ± 0.4 and 4.4 ± 0.4. Individual differences were observed (P<0.05) for partial and total exposure, flehmen responses, mounts without erection and pelvic copulatory movements. The variables flehmen responses, retreats away from the female and mounts without erection showed significant differences (P<0.05) between ejaculates. Seasonal effects on sexual behavior characteristics were not found. However, a monthly effect was noted for flehmen responses, partial exposure of the penis, mounts without erection, retreats away from the female and pelvic copulatory movements when the 2 ejaculates were combined.