180 Effects of different synchronization protocols on metabolic profile, progesterone levels, and reproductive performance of dairy goats

Understanding and optimizing oestrus detection efficiency in goats is vital for effective breeding. This study investigated the impact of two oestrus synchronization protocols on blood metabolic profile, progesterone levels, and birth outcomes after natural breeding in dairy goats. Forty mature does (3.9 ± 0.28 years) were divided equally between the two protocols, namely, prostaglandin F2α (PGF2α; protocol 1) and PGF2α plus gonadotropin-releasing hormone (GnRH; protocol 2) with 10 Alpine and 10 Saanen females in each protocol. In protocol 1, each doe received two injections of 10 mg PGF2α on Day 0 and Day 11. In protocol 2, each doe received 10 mg of PGF2α injection on Day 0, and 43 µg GnRH injection on Day 9 to initiate an LH surge and subsequent ovulation, thus hypothesized to potentially improve the efficiency of oestrus synchronization, followed by a second dose of 10-mg PGF2α injection on Day 11. Oestrus signs were observed, and natural breeding was conducted at 24–36 h after the second dose of PGF2α. Blood samples were collected on Day 12 and Day 21 post-breeding for evaluation of cholesterol, glucose, and triglyceride concentrations. Furthermore, progesterone levels were estimated on plasma samples collected on Day 3, 9, 15, and 21 post-breeding. Data were presented as means ± s.e. and analysed by one-way analysis of variance, followed by post hoc Tukey’s test. No significant differences were observed in cholesterol, glucose, and triglyceride levels between the two protocols. However, progesterone levels were higher (P ≤ 0.05) in protocol 1 on Day 3 post-breeding, with no significant differences recorded on Days 9, 15, and 21. No significant differences were observed on pregnancy rates between the two protocols as diagnosed by ultrasonography on Day 50 post-breeding (71% vs 67%, for protocols 1, and 2, respectively). However, irrespective of the protocol, Alpine showed higher (P ≤ 0.05) pregnancy rates than Saanen goats. Kidding percentage was higher (P ≤ 0.05) in protocol 1 compared with protocol 2 (90% vs 65%). No significant differences were observed in kids’ birthweight between the two protocols. In conclusion, while metabolic parameters remained largely unaffected by the two protocols, higher values were observed in the progesterone levels at Day 3 post-breeding in protocol 1. The higher kidding percentage in protocol 1 suggests that PGF2α alone may provide more efficacious approach for oestrus synchronization in Alpine and Saanen goats than PGF2α plus GnRH (protocol 2). Further research is warranted to understand the underlying mechanisms and optimize goat breeding strategies.