FERTILIZATION IN SWINE AND CATTLE

Fertilization and its prerequisites, i.e., sperm transport, capacitation and oocyte maturation, were discussed with emphasis on the occurrence of these processes in the pig and cow. Attempts to fertilize procine and bovine ova in a micro-droplet system which was used successfully to fertilize mouse and hamster ova were not successful. Many droplets contained highly motile spermatozoa which were effective in removing the follicular cells from around the zonae. Spermatozoa attached to the zonae but did not penetrate the ova in vitro. No motile bull or boar spermatozoa with an acrosome reaction were observed in the droplets. When droplets which contained boar spermatozoa and pig follicular oocytes for 4 h were transferred into the oviducts of estrous females, spermatozoa exhibited acrosome reactions and ova were penetrated. Reducing oocyte maturation time and injecting progesterone before ovulation increased (P < 0.05) the incidence of polyspermy in pigs. Bovine oocytes underwent maturation and were penetrated by bull spermatozoa in pig oviducts. Culture systems, other than the oviduct, did not provide satisfactory conditions for fertilization of bovine or porcine ova.