Conception Rate, Farrowing Rate and Litter Size after Intrauterine Insemination with Cryopreserved Boar Semen in Spontaneous and Induced Ovulation Sows

Introduction The procedure for artificial insemination (AI) in pigs using cryopreserved semen involves the deposition of a high number of cryopreserved spermatozoa (5-6 x10 cells) in a large volume of diluent (80-100 ml) into the cervix. Despite inseminating with this high sperm number, low fertility levels are usually obtained (about 20-30% conception and farrowing rates and 2-3 total piglets born per litter lower than those achieved by fresh semen) (1, 2). Therefore, the use of cryopreserved semen in commercial AI swine herds is still limited (3). Recently, a procedure for non-surgical intrauterine insemination (IUI) in sows, which allows the transcervical deposition of semen into the uterine body, has been developed (4, 5). The fertility rates achieved by IUI with fresh semen using 1x10 spermatozoa per dose were comparable to those of conventional AI with 3x10 spermatozoa per dose (4). Furthermore, it has been demonstrated that the number of spermatozoa in the sperm reservoir at about 24 h after insemination was not significantly different between IUI and conventional AI (8). However, no fertility data are available using IUI with cryopreserved boar semen. The present study was conducted to evaluate fertility of sows after IUI with cryopreserved semen under field conditions.