Regulation of Pituitary Gene Expression in Lines of Swine with Different Ovulation Rates

of GnRH receptor and gonadotropin subunit gene expression were measured by quantitative PCR.­ Levels of gene expression for the GnRH receptor and gonadotropin subunits decreased following treatment with the GnRH antagonist in pituitaries of gilts from the Index and Control lines; however, these values remained unchanged in pituitar-ies from Meish­an gilts. Identification of unique genetic changes in swine strains with increased ovulation rates, such as the Chinese Meishan and the UNL Index selection line, may allow for a better understanding of prolifi-cacy.­ This critical information may also be used to enhance litter size in other lines of pigs and improve efficiency of pig production.­