Age-specific optimization of ovarian superstimulation, oocyte maturation, and somatic cell nuclear transfer in juvenile and adult goats.

Abstract

Juvenile in vitro embryo transfer can shorten generation intervals, but its application in goats is constrained by the quantity-quality trade-off in oocytes from prepubertal donors. We established an age-specific workflow for Yudong black goats by separately optimizing ovarian superstimulation in juvenile and adult donors, evaluating anti-Müllerian hormone (AMH) as an exploratory indicator of ovarian response, improving in vitro maturation (IVM), and optimizing somatic cell nuclear transfer (SCNT). Under the selected juvenile protocol (1-2 months, 220 IU FSH plus 330 IU PMSG, collection 12 h after the final FSH injection), donors yielded 113.4 ± 10.9 follicles and 73.5 ± 6.3 cumulus-oocyte complexes, with 35.9 ± 0.9% Grade A/B oocytes. Pre-stimulation serum AMH was positively associated with follicle number; an exploratory cutoff of 4.54 ng/mL predicted ≥ 90 follicles (AUC 0.906; sensitivity 87.5%; specificity 80.0%). Supplementing IVM medium with 20% adult follicular fluid increased juvenile oocyte maturation from 53.7 ± 0.8% to 62.2 ± 0.8% and reduced intracellular reactive oxygen species. Optimal electrofusion voltages were 18 V for juvenile and 21 V for adult cytoplasts. Adult-derived parthenogenetic embryos had higher blastocyst rates than juvenile-derived embryos. SCNT embryos were transferred at the 2-4-cell stage; therefore, no in vitro SCNT blastocyst endpoint was generated. Preliminary Day-45 pregnancy establishment was 1/6 recipients for each cytoplast source. These findings support an age-specific, conservation-oriented workflow while emphasizing the need for independent AMH validation, minimally invasive oocyte recovery, and larger full-term SCNT studies.