Fertility of Male Syrian Hamsters Paired with One, Two and Four Proestrous Females Each

Comparison of Copulatory Behavior in Male Syrian Hamsters Paired with One, Two and Four Proestrous Females Each

“…These results are substantially the same as those of our previous study on the male fertility after overnight mating (6/7 in the 1 : 1, 7/14 in the 1 : 2 and 4/28 in the 1 : 4 mating groups) [10]. The median frequency of mounting, intromission and ejaculation in the 1 : 1 mating group was 27, 36 and 2, respectively.…”

“…The frequency of both intromission and ejaculation in the 1 : 4 mating group was significantly lower than that in the 1 : 1 and 1 : 2 mating groups (P<0.01 and P<0.05) ( Table 1). The male fertility rates for the males caged with 1, 2 or 4 females for 30 minutes in the present study were similar to those observed in our previous study of overnight mating [10]. To clarify the cause of the lower male fertility rates in the 1: 2 and 1: 4 mating groups, we further observed copulating behaviors for 30 minutes in Experiment II.…”

“…Of the 7 males in this group, there was only 1 whose both partners became pregnant to term. When this finding is combined with the results of our previous experiment on overnight mating [10], we can conclude that males do not have the ability to successfully copulate with 2 females at a time.…”

“…These findings allow us to presume that if the male fertility rate after 30-minute mating does not differ from that after overnight mating [10], observation of copulating behaviors for 30 minutes will allow determination of the causes of the reduced fertility rate. Based on this presumption, the following experiments were undertaken.…”

Copulatory Behavior and Fertility of Male House Musk Shrews (Suncus murinus) Paired with One, Two and Four Females Each

“…Therefore, improved husbandry of house musk shrews is needed to support research into this animal. In past studies, the reproduction rate of rats was successfully improved using polygamous mating [12], but that of Syrian hamsters was not [13]. There has been no report about the improvement of reproduction in house musk shrews.…”