Effect of exogenous GnRH, semen volume, and artificial insemination technique on reproductive performance of Saanen goats in Sri Lanka

The global demand for goat production is rising to meet the growing needs for meat and milk. Artificial insemination (AI) using elite buck semen enhances herd productivity but often faces suboptimal success rates influenced by semen type, oestrous synchronization, insemination method, geographical region, breed, etc. The objective of this study was to assess the pregnancy rate in Saanen goats following three distinct interventions: the administration of GnRH at the time of AI, the use of two semen straws/doses (0.25 ml × 2) for insemination, and the use of a makeshift AI gun for insemination. In this experiment, clinically healthy, non-pregnant does (n = 148), 2–4 months after kidding, were randomly assigned to four groups: a Control Group (CG) and three Treatment Groups (TG1, TG2, and TG3). Oestrous synchronization involved intravaginal progesterone-releasing devices (CIDR) and 400 IU Pregnant Mare Serum Gonadotropin at device removal, with AI performed 48–56 hours later. Control Group (n=52), TG1 (n=48), and TG2 (n=22) were inseminated using a conventional AI gun, while TG2 received two semen doses. TG1 received 100 µg GnRH intramuscularly at AI, and TG3 (n=26) used a makeshift AI gun with the same single dose of semen. Pregnancy confirmation was carried out via transrectal ultrasound at 45-days post-insemination. Pregnancy rates were TG1: 75.0%, TG2: 81.8%, TG3: 50.0%, and CG: 42.3%. GnRH administration and two semen straws/doses protocols significantly improved the pregnancy rates (p<0.05), while GnRH also significantly increased twinning rates (p<0.05). The makeshift AI gun showed remarkable cost-effectiveness for large-scale use. These findings highlight strategies to enhance reproductive performance in goats, particularly in upcountry farms in Sri Lanka.