Reproduction in Pigs Using Frozen-Thawed Spermatozoa from Epididymis Stored at 4 C

Abstract

The ability of frozen-thawed boar spermatozoa obtained from epididymides stored at 4 C for 1 day to produce piglets after Fallopian insemination or in vitro fertilization (IVF) of in vitro matured (IVM) oocytes was examined. To test their in vivo fertilization ability, frozen-thawed spermatozoa from 2 boars, which had already shown IVF ability, were introduced into the Fallopian tubes of estrus-synchronized gilts. Embryo collection on the 7th day post-insemination revealed that one of two batches of spermatozoa had an ability of fertilization in vivo and that fertilized oocytes could develop to blastocysts. Three of 6 gilts inseminated with one batch of spermatozoa became pregnant and one of them farrowed 2 normal piglets (1 male and 1 female). IVM oocytes fertilized in vitro by the same spermatozoa were transferred to 3 recipients (200 oocytes per recipient). One of them became pregnant and farrowed 5 normal piglets (3 males and 2 females). The results indicate that boar spermatozoa collected from epididymides stored for 1 day at 4 C and then frozen have the ability to produce piglets. The new cryopreservation protocol and reproductive technology described here can enhance conservation of boar genetic resources when the collection site of the epididymides is far from a laboratory.