Effect of processing of semen on capacitation time of fresh and frozen-thawed boar spermatozoa.

Ovulation time of gilts was controlled by oral treatment with altrenogest (17-allyl-hydroxyestra-4,9,11-trien-3-one) followed by gonadotropic hormone injections. Gilts were laparotomized 42 to 44 h after injection of human chorionic gonadotropin. Spermatozoa were surgically placed into ligated oviducts of gilts after one of the following semen treatments: frozen and thawed in Beltsville thawing solution (F-BTS) or in seminal plasma (F-SP); unfrozen, processed like the frozen semen, but not cooled, frozen or thawed, and extended in Beltsville thawing solution (U-BTS) or in seminal plasma (U-SP). Ova were recovered 5 or 24 h after insemination and their stage of development was determined. At 5 h, F-BTS and U-BTS spermatozoa had fertilized significantly more ova (45 and 69%, respectively) than the F-SP and U-SP spermatozoa (5 and 34%, respectively). Ova fertilized by F-BTS and U-BTS spermatozoa had reached a more advanced stage of development than ova fertilized by F-SP and U-SP spermatozoa at both recovery times. Unfrozen spermatozoa (U-BTS or U-SP) fertilized more ova by 5 h after tubal deposition than F-BTS or F-SP spermatozoa (P less than .005 for each comparison). By 24 h, the percentage of fertilized ova was similar for all treatments. The results indicate that semen processing reduced capacitation time of boar spermatozoa to an extent similar to passage through the uterus. The capacitation time of frozen-thawed spermatozoa appeared to be similar to spermatozoa that were processed, but not cooled, frozen or thawed.