Inducing Ovulation with hCG Improves Fertility Outcomes of Co-Dominant Follicle Drainage to Avoid Twin Pregnancy in Dairy Cows

SIMPLE SUMMARY: In dairy herds, twin pregnancies considerably compromise cow welfare, reducing their lifespan and leading to the increased use of antibiotics postpartum. In cows with follicles of pre-ovulatory size at insemination, twins can be avoided by puncturing and draining one follicle. In this report, we propose the use of a recently described manual method of follicular drainage without the need for ultrasound guidance and its association with treatment of the animal with human chorionic gonadotrophin (hCG), thus also increasing fertility compared to the use of Gonadotrophin releasing hormone (GnRH). The manual follicular drainage technique is simple, takes less than 1 min, and can be performed by a clinical veterinarian. In this study, even during heat stress periods follicle drainage plus hCG treatment gave rise to nearly 50% of pregnancies relative to conception rates, compared to 29% observed in non-drained, non-treated control animals or 20% in animals drained and treated with GnRH. This approach is recommended for weekly reproductive program visits. ABSTRACT: Twin pregnancies are undesirable in dairy cattle as they dramatically compromise cow lifespan and, consequently, herd economy. Clinical problems in cows arise from the time of pregnancy diagnosis to pregnancy loss, abortion, or parturition. The drainage of co-dominant follicles in cows with two or more follicles at insemination prevents twin pregnancy. The objective of this study was to compare the effectiveness of draining the smaller of two follicles through a simplified maneuver not requiring ultrasonography in cows in their third or more lactation, and then inducing ovulation immediately before artificial insemination (AI) with GnRH or human chorionic gonadotrophin (hCG). Animals were monitored by ultrasound at AI and randomly assigned to the groups: follicular drainage and treatment with GnRH (Deph; n = 60), follicular drainage and treatment with hCG (hCG; n = 60), and non-drainage (ND; n = 60) as control cows. On the basis of odds ratios, cows treated with hCG were 2.1 times more likely to become pregnant than control animals. Our results reveal the efficacy of hCG treatment at AI in cows with two follicles of pre-ovulatory size subjected to a simple follicular drainage procedure.