Effect of a Single Injection of GnRH Analog Alone and at the Time of AI on Reproductive Performance of Nili Ravi Buffaloes

Abstract

Introduction: The gonadotropin-releasing hormone (GnRH) is a decapeptide hormone released from basal neurons of the hypothalamus. It stimulates the production of follicle-stimulating hormone (FSH) and luteinizing hormone (LH) in the pituitary. The objective of the study was to evaluate the effect of a single injection of gonadotropin-releasing hormone (GnRH) analog at the time of artificial insemination (AI) on buffalo estrus, conception, pregnancy, and calving rate. Materials and methods: The anestrus nulliparous Nili Ravi buffalo heifers (n=80) were divided into 4 groups randomly. Group A (n=20) received only a single injection of GnRH analog at start of the experiment (Day 0), group B (n=20) received a single injection of GnRH analog at Day 0 and prostaglandine (PGF2α) at Day 7, group C (n=20) received progesterone sponge for 7 days, and group D (n=20) received progesterone sponge for 7 days and PGF2α at Day 9. In 2nd study, buffaloes (n=60) expressing first (n=20), second (n=20), and third (n=20) postpartum estrus were enrolled. Moreover, heifers (n=20), expressing estrus first time were also included. Animals (n=10) from each group, received a single injection of GnRH analog at the time of AI were named as treatment group and the control (n=10) did not receive any treatment. Pregnancy tests were performed with the help of ultrasound on days 35 and 65 post-AI. Results: The pregnancy and calving rates were lower in GnRH group compared to other treatments. Similarly, the administration of GnRH analog did not increase pregnancy rates in treatment groups. Conclusion: The single injection of GnRH analog alone at the time of AI did not improve the reproductive performance of buffaloes.