TWO SEXUALLY ACTIVE BUCKS HOUSED WITH FOUR SUCCESSIVE GROUPS OF ANOVULATORY DOES INDUCED HIGH PREGNANCY RATES DURING SEVEN-DAY MATING PERIODS

Abstract

Background. In seasonally anovulatory goats, sexually active bucks led a high pregnancy rate during a mating period of 36 days. Progesterone priming of does can reduce the length of the mating period while maintaining high fertility by allowing oestrous behaviour at the first male-induced ovulation. Objective. To determine whether high fertilization rates could be achieved by using two sexually active bucks, alternated daily for a period of seven days in four successive groups of does. Methodology. Two control bucks were used only with one group of does (n = 19), whereas two experimental bucks were successively housed with four groups of does (n = 18 or 19 each). One of the control and experimental bucks was introduced to their respective groups in the morning and removed 24 h later to rest for 24 h. Immediately after the removal of the first buck, the second buck was placed with the group of does. Each doe was treated with 25 mg of progesterone im 48 h prior to the first introduction of bucks to reduce short ovulatory cycles. Results. In each group, the proportion of does that ovulated was higher than 93%. These proportions did not differ among groups exposed to the control or experimental bucks (P > 0.05). In each group, the proportion of pregnant does was higher than 78%; proportions did not differ among groups (P > 0.05). Implications. At farms with few bucks, efficient management of sexually active bucks can yield a high percentage of pregnant females. Conclusion. These results indicate that two sexually active bucks housed with four successive groups of progesterone-treated anovulatory does during a mating period of seven days were able to achieve high pregnancy rates.