Collection of Early Embryos from Gilts after Natural or Induced Ovulation.

The embryo recovery rate was compared between Landrace •~ Large White F1 gilts following natural (n=112) and induced ovulation with PMS and hCG (n=74). Embryo collection was carried out by laparotomy 2 to 7 days after the end of estrus. The average numbers of corpora lutea after induced ovulation was significantly higher than that in natural ovulation (21.9 vs 13.3, P<0.01). Significantly higher number of embryos were recovered by induced ovulation than that after natural ovulation (20.6 vs 12.3, P<0.01). The average number (percentage) of normal embryos was 17.3 (83.9%) or 11.7 (95%) after induced or natural ovulation (P<0.01). The difference in percentage of normal embryos recovered was significant (P<0.01).