NCSynch: A novel, progestagen-free protocol for ovulation synchronization and timed artificial insemination in goats

The objective of this study was to compare overall pregnancy success achieved using a combined ovulation synchronization-timed artificial insemination (NCSynch-TAI) protocol with that obtained using estrus synchronization and artificial insemination (AI). Multiparous Boer and Boer-cross does (n = 132) were randomly assigned within age (year 1) or parity (years 2 and 3) to one of two treatments. Control does received 15 mg prostaglandin F (PGF; Lutalyse®) on days 1 and 10 of treatment. Estrus onset was checked twice daily with separately penned, intact bucks (year 1) or a vasectomized buck penned with the does (years 2 and 3). Control does were bred by AI 12 h after estrus onset using frozen semen. NCSynch-TAI does received 15 mg PGF on day 1 of treatment. Does received 50 g GnRH (Cystorelin®) on day 8, and 15 mg PGF was given on day 15. On day 18, NCSynch-TAI does were appointment bred using frozen semen and received 50 g GnRH at breeding. Pregnancy status was determined using transabdominal ultrasonagraphy with kidding rates also recorded. In year 1, 13 of 15 control does (87%) were detected in estrus with 8 pregnant to AI for an overall pregnancy rate of 53%. For NCSynch-TAI, 15 does were bred and 11 (73%) became pregnant. In year 2, 24 of 26 controls (92%) were detected in estrus with 19 pregnant to AI (73% overall pregnancy rate). For NCSynch-TAI, 26 does were bred and 20 (77%) became pregnant. In year 3, 21 of 25 controls (84%) were detected in estrus with 8 pregnant to AI (32% overall pregnancy rate). For NCSynch-TAI, 25 does were bred and 14 (56%) became pregnant. Across all years, the overall pregnancy rate for NCSynch-TAI does (45/66, 68%) did not differ (P = 0.075) compared to controls (35/66; 53%). Kidding rates for the two treatments (68% vs. 51%, respectively) also did not differ (P = 0.075). In summary, pregnancy success following the use of NCSynch-TAI was comparable to that obtained when does were bred based on detection of estrus.