Objective:
The National Animal Germplasm Program (NAGP) and the Cooperator (Purdue University, Department of Animal) desire to enter into this Cooperative Agreement for the purpose of developing the NAGP swine germplasm collection by (1) Characterizing the relationships of measures of semen quality and numbers sperm cell inseminated to resulting conception rates and litter size; and (2) Evaluating alternative commercially available semen extenders for their efficacy in cell preservation during transportation. Such an effort is consistent with the goals of the NAGP and Purdue University. The above steps are critical in utilizing a collection of swine germplasm to regenerate live animals.

Approach:
Cryopreservation of boar semen has been utilized for several decades. However, unlike other livestock species, such as the bovine, boar spermatozoa are sensitive to cryopreservation and only approximately 50% of the spermatozoa survive the cryopreservation procedure (Watson, 1995). Utilizing frozen/thawed (FT) boar semen with traditional intra-cervical insemination requires high numbers of sperm cells (5-6 x 109) to be used and conception rates achieved are less than attained with liquid-stored fresh boar semen (Johnson et al., 2000). These factors limit the utilization of FT semen on commercial swine operations. However, cryopreservation of boar semen is beneficial for numerous reasons such as for gene banking boars of high genetic merit and for preserving genetic diversity (Guthrie and Welch, 2005). When these fore mentioned procedures are utilized the amount of cyropreserved semen available is often limited. Therefore, improved methods to inseminate sows with FT boar semen are required. A potential solution to reduce the number of FT spermatozoa required for successful conception is intrauterine insemination (IUI). IUI places the semen closer in proximity to the site of fertilization compared to traditional intra-cervical insemination and thus, has the potential to reduce the number of spermatozoa required. Additionally, IUI may be beneficial when inferior spermatozoa are being used, such as the case with FT semen. It has been demonstrated that fewer spermatozoa are needed with IUI to achieve similar conception rates and litter sizes as traditional intra-cervical insemination when fresh semen is used (Watson and Behan, 2002). Therefore, the objective of this research is to determine the minimum number of FT spermatozoa needed to achieve acceptable conception rates when IUI is utilized. Objectives: Determine the minimum number of spermatozoa required and most effective insemination schedule to achieve acceptable conception rates when FT semen is used in conjunction with IUI. Rationale: When utilizing gene banked cryopreserved boar semen the amount of FTsemen available to use is often limited. Hence, more efficacious methods to utilize FT boar semen are needed to maximize conception rate and litter size while simultaneously minimizing the number of spermatozoa required. A potential method to minimizing the number of FT spermatozoa needed while maintaining acceptable conception rates and liter sizes while is IUI. However, limited data is available on the efficacy of IUI with FT boar semen or the minimum number of FT spermatozoa required to achieve acceptable reproductive performance when used in combination with IUI.