The effect of administering equine chorionic gonadotropin (eCG) and human chorionic gonadotropin (hCG) post artificial insemination on fertility of lactating dairy cows.

The research examines the impact of using equine chorionic gonadotropin (eCG) and human chorionic gonadotropin (hCG) post artificial insemination (AI) on the fertility rates of lactating dairy cows, revealing the fertility enhancement, especially for cows in low body condition, and decrease in pregnancy losses when eCG is given 7 days prior to hCG.

Introduction

• The study aimed to evaluate the effects of administering equine chorionic gonadotropin (eCG) and human chorionic gonadotropin (hCG) after artificial insemination (AI) on the fertility of lactating dairy cows.
• It was hypothesized that the use of these hormones might increase the chances of successful pregnancies in these animals.

Methodology

• The research was split into three distinct experiments, involving the treatment of cows with either eCG, hCG, a combination of both, or no treatment.
• In the first experiment, a selection of cows were treated with eCG 22 days after AI. On day 29, pregnant cows were treated with hCG. The levels of pregnancy and progesterone were evaluated on days 29 and 45.
• The second experiment involved similar treatments with smaller sample sizes, with blood sampling and ultrasonography conducted between days 22 and 45.
• In the third experiment, cows were treated with eCG on day 22 post-AI and pregnancy results were evaluated on Day 36 and 85.

Results

• In the first experiment, the use of eCG on Day 22 resulted in a significant increase in the number of pregnant cows by Day 29 and Day 45. The fertility increase was notably higher in cows with timed AI than in cows AI at detected estrus.
• Pregnancy losses were found to be reduced by eCG and hCG administration, but increased in the group of cows that were not given eCG but were treated with hCG subsequently.
• In the second experiment, hCG contributed to an increase in the number of accessory corpus luteum (a structure in the ovary related to fertility) on Day 35 and a higher level of progesterone.
• The third experiment demonstrated an increase in fertility in cows treated with eCG, but only in those cows which had a low body condition.

Conclusion

• The results suggest that eCG administration 22 days post insemination increased fertility, particularly in cows with low body condition and reduced pregnancy losses if given 7 days before hCG.
• The hCG treatment induced accessory corpus luteums and slightly increased progesterone, but when given in the absence of a prior eCG treatment, it reduced fertility.