eng Rovedar Farm Animal Health and Nutrition 2980-7905 2024-03-25 3 1 17 21 10.58803/fahn.v3i1.38 40 Muhammad Binyameen 0 https://orcid.org/0000-0002-4403-2480 Muhammad Imran 0 Muhammad Waseem 0 Saba Anwar 1 https://orcid.org/0009-0008-9134-0110 Hina Tahir 0 https://orcid.org/0009-0002-3967-2341 Burhan Azam 2 Muhammad Asim Tauseef 3 https://orcid.org/0000-0003-1971-409X Muhammad Saleem 4 https://orcid.org/0000-0002-0858-9169 Buffalo Research Institute, Pattoki District Kasur 55300, Pakistan Buffalo Research Institute, Pattoki District Kasur 55300, Pakistan Livestock Experiment station Bhunikey, Pattoki District Kasur 55300, Pakistan Livestock Experiment station Bhunikey, Pattoki District Kasur 55300, Pakistan Theriogenology Department, Faculty of Veterinary and Animal Sciences, Islamia University, Bhawalpur, 63100, Pakistan 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.        https://fahn.rovedar.com/index.php/FAHN/article/view/38 Buffalo Heifer Pregnancy rate Sponge Synchronization