Evaluation of the Efficiency of Different Oestrous Syncharonisation Protocols Used in Dairy Goats: A Pilot Study in Sri Lanka

Hormonal control of ovulation improves breeding efficiency by shortening the breeding period and enabling fixed-time artificial insemination (FTAI). In goats, oestrous synchronisation is essential for successful AI. Although Controlled Internal Drug Release (CIDR)-based protocols are widely used, they require the concurrent administration of pregnant mare serum gonadotrophin (PMSG), increasing the overall cost of treatment. This pilot study evaluated the efficacy and economic feasibility of five oestrous synchronisation protocols for oestrus induction in dairy goats, to identify practical alternatives to conventional CIDR-based methods under Sri Lankan conditions. A total of 52 healthy, non-pregnant Saanen does, with a body condition score of 2.5 - 3.0 were randomly assigned to five FTAI protocols: a) CIDR-Long (n=10), (CIDR for 18 days); b) CIDR-Short (n= 10), (CIDR for 10 days); both groups received 400 IU PMSG at  device removal, and FTAI 48-56 hours later; c) 2PG-GH (n=10): PGF_2ᾳ on Day 0 and 7, PMSG on Day 7, GnRH on Day 9, and FTAI 48-56 hours later; d) Ovsynch (n=7): GnRH on Day 0, PGF_2ᾳ on Day 7, GnRH on Day 9, and FTAI 16-20 hours later; e) NCsynch (n=11): PGF_2ᾳ on Day 0 and 14, GnRH on Day 7, FTAI on Day 17. Animals were assessed for six behavioural and physical signs of oestrus at insemination, and pregnancy was confirmed by ultrasonography 45 days after AI. Oestrus intensity, ranked from highest to lowest, was CIDR-Short (85.5%), NCsynch (82.4%), CIDR-Long (81.2%), Ovsynch (67.3%), and 2PG-GH (18.8%). Pregnancy rates were 50.0%, 40.0%, 10.0%, 42.8%, and 63.6% for the CIDR-Long, CIDR-Short, 2PG-GH, Ovsynch, and NCsynch groups, respectively. Although differences among protocols were not statistically significant (p > 0.05), Ovsynch and NCsynch achieved pregnancy rates of 42.8% and 63.6%, respectively, comparable to the CIDR-Long protocol. These hormone-only protocols were approximately 66.7% more cost-effective than CIDR-based treatments and were associated with fewer vaginal reactions and infections, thereby reducing the potential need for antimicrobial therapy. Larger-scale studies are warranted to confirm their efficacy and potential to improve reproductive performance while reducing the costs and health risks associated with intravaginal progesterone devices.