Abstract
The aim of this study was to determine the effectiveness of an intravaginal drug-releasing device commercially produced for use in goats and sheep (CIDR-G device) at inducing estrus in sows. Thirteen Landrace sows were used in the this study, and the sows were randomly divided into three groups: group A (n=5), group B (n=4) and group C (n=4). Two CIDR-G devices were inserted into the vagina of each sow in groups A and B, and one CIDR-G device was inserted into the vagina of each sow in group C. The device was removed from each sow on the seventh day after insertion, and 0.2625 mg of PGF2α was applied to the vulva of each sow in groups A and C. All five sows in group A and all four sows in group C, the two groups of sows that were administered PGF2α, showed onset of estrus 3-5 days and 2-4 days after removal of the CIDR-G device, respectively. Three of the four sows in group C showed onset of estrus on the second day after removal of the device. On the other hand, onset of estrus was observed (on day 3 after removal of the device) in only one of the four sows in group B, the group of sows that were not administered PGF2α. Saliva progesterone concentrations continued to rise in both groups A and C after insertion of the device, and the saliva concentrations of progesterone on day 5 after insertion in these two groups were significantly higher than those just prior to insertion of the device (p<0.05). The number of devices inserted had no effect on the saliva progesterone concentration. The results of this study showed that insertion of a CIDR-G device for a period of seven days followed by application of PGF2α to the vulva is effective for induction of estrus in the swine.
