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

Abstract

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 15mg 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 12h after estrus onset using frozen semen. NCSynch-TAI does received 15mg PGF on day 1 of treatment. Does received 50μg GnRH (Cystorelin®) on day 8, and 15mg PGF was given on day 15. On day 18, NCSynch-TAI does were appointment bred using frozen semen and received 50μg 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.