Abstract
The results of an experiment to determine the effectiveness of prostaglandin analogues to induce estrous synchronization of cattle are presented. There were 257 experimental animals and 119 control animals. 44 cattle that had histories of fertility disturbances were studied separately to determine if the estrous synchronization could improve fertility. The 257 experimental animals were given 2 .5 mg injections im of ICI 80,996 (ICI) with an interval of 10 or 11 days between injections. Then artificial insemination was administered 63 or 75 hours after the 2nd ICI injection. 1 group of cattle underwent artificial insemination both 75 and 99 hours after the 2nd ICI injection. 47 cattle received a 1.5 mg injection im of gonadotropin-releasing hormone (GnRH) in conjunction with artificial insemination. Fertility was not significantly higher among the animals treated with prostaglandin analogues than among the control animals. 61% of the experimental animals had mature follicles at the time of artificial insemination with a 65% conception rate. The animals given GnRH showed a higher rate of conception compared with the control group, and the animals showed the highest rate of conception. Intensive tests done on 16 cattle showed that a complete luteolysis occurred 15-24 hours after treatment, the luteinizing hormone (LH) peak occurred 51-100 hours after treatment, and ovulation occurred 69-120 hours after treatment. The cattle that received GnRH injections in conjunction with artificial insemination showed a peak LH level 3 hours after the GnRH injection.
| Original language | English |
|---|---|
| Pages (from-to) | 7-18 |
| Number of pages | 12 |
| Journal | Zuchthygiene |
| Volume | 11 |
| Issue number | 1 |
| State | Published - 1976 |