Intraperitoneal insemination of the guinea pig with synchronized estrus induced by progesterone implant

Female guinea pigs with synchronized ovulation by means of implantation of progesterone-filled tubing (P-tube) followed by a progesterone injection, were inseminated by intraperitoneal injection with sperm suspension. First, to obtain the optimum conditions for insemination, the females were inseminated singly over the range of 1-10 x 10(7) spermatozoa before and after the synchronized ovulation. The incidence of conception and implantation was 100% in the females given more than 5 x 10(7)/animal at 9:00 h on the 5th day after removal of the P-tube. Second, the reproductive ability of the inseminated females under this optimal condition was observed throughout the pregnancy to delivery. Inseminated females had a mean +/- S.D. gestation period of 68.7 +/- 0.5 days, a litter size of 2.8 +/- 0.6 pups and body weight of 110 +/- 14 g. These data were comparable to those of naturally-mated females. Our findings suggest that the artificial insemination by intraperitoneal injection in combination with the synchronized estrus technique is very useful for production control in a small colony of guinea pigs.