Abstract
Estrus induction is an important step in embryo production. It has been difficult to induce estrus in miniature pigs by intramascular (i.m.) injection of prostaglandin F2α (PGF22α) in the early luteal stage of the estrous cycle. In the present study, we injected two different doses of PGF22α i.m. and into the submucosa of the vaginal vestibule (i.ves.) of miniature pigs, and examined the effect of these treatments on estrus induction. Fifteen miniature pigs were divided into five experimental groups (control, saline injected i.m.; PGF2α treated, 1.0 or 1.5 mg of PGF2α injected twice i.m. or i.ves.), and the estrus length and concentrations of 17β-estradiol (E2) and progesterone (P) in the blood were examined. Estrus length was significantly shortened by a large amount of PGF2α injected i.ves. In addition, the concentration of P in the blood significantly decreased after two injections of PGF2α (i.m. or i.ves.). These results suggest that in miniature pigs, administration of at least 3.0 mg of PGF2α is required for the induction of luteolysis and injection of PGF2α into the vaginal vestibule is a useful method of estrus induction.
