Proceedings of the New Zealand Society of Animal Production.
1987, 47: 65-68
Proceedings of the New Zealand Society of Animal Production.
1987, 47: 65-68
The prostaglandin injection did not alter interval from calving to first oestrus (48.5 d), start of the artificial breeding (AB) programme to first insemination (12.9 d), AB start to conception (24.8 d), calving to insemination (77.2 d), calving to conception (88.3 d), or the pregnancy rate to first insemination (58.5%), even though there were large differences in each of these parameters among the 5 herds in Trial 1.
The pregnancy rate to first insemination among cows induced to calve prematurely was 47.2% compared to 56.7% in normally calving herdmates with similar calving dates (Trial 2. A prostaglandin injection around 20 d post-partum did not affect this difference. In Trial 3, induced cows injected with prostaglandin from 28 to 34 d post-partum did have a higher pregnancy rate to first insemination than untreated induced herdmates (69.2% v 42.3%). None of the parameters used to measure reproductive efficiency were affected by a prostaglandin injection given from 28 to 34 d post-partum to normally calving cows in Trial 3.
The comparatively high level of fertility in the cows, combined with efficient breeding management in the herds included in these trials, may have minimised the potential usefulness of this form of prostaglandin therapy previously demonstrated in herds with less fertile cows.
Keywords: NZSAPAB; Prostaglandin; post-partum; fertility; conception; pregnancy
