ABSTRACT
With an increased interest in transgenic animal production, the caprine species offers many advantages, and the prepubertal goat is a potential source of large numbers of oocytes for in vitro embryo production. The aim of the present study was to evaluate the follicular response and recovery of oocytes from prepubertal and adult goats following ovarian stimulation and laparoscopic recovery, and their developmental competence following culture in semi-defined media. Oocytes were collected over a 15-week period from prepubertal goats (3-7 months old) and adult controls (2-4 years old) that had been subjected to estrus synchronization and ovarian stimulation. Following insemination, zygotes were cultured for 96h in G1.2 followed by an additional 120h in G2.2. Morulae and blastocysts were scored using light microscopy on Days 7 and 9 followed by fluorescent staining for cell counts on Day 9 (216h postinsemination). The mean numbers of follicles aspirated and oocytes recovered were significantly greater for prepubertal than for adult goats (P<0.01). The number of oocytes recovered from prepubertal goats was observed to decline significantly with increasing age of the animals (P<0.05). The proportion of oocytes that matured and cleaved did not differ significantly between prepubertal and adult goats. Furthermore, no significant differences in morulae development (percentage of those cleaved), 5% versus 4%, or blastocyst development, 6% versus 7%, were observed for prepubertal and adult derived oocytes (P>0.1), respectively. Mean cell number per blastocyst also did not differ significantly. In conclusion, higher yields of oocytes were obtained from gonadotrophin-primed, prepubertal does than from adults, while in vitro development was similar.
