B.J. Isler*, K.M. Irvin1*, M.F. Rothschild#, and G. J. Evans**
*The Ohio State University Department of Animal Sciences
#Iowa State University Department of Animal Science
**PIC Group
Abstract
Previous studies by Iowa State University and PIC have shown the prolactin receptor (PRLR) gene to be positively associated with litter traits in swine. At this time, research is lacking in the examination of the association between PRLR genotype and components of the reproductive system itself. In the current study, the PRLR gene was investigated as a potential candidate gene influencing reproductive tract components in swine. A total of 46 Yorkshire, 27 Large White, and 69 crossbred females were genotyped at the PRLR locus and classified as genotype 11, 12, or 22. Females were mated to Hampshire boars and slaughtered at approximately 75 days of gestation. Data collected from gravid uterine tracts included ovulation rate, uterine weight, uterine horn length, number of fetuses, total fetal weight, average fetal weight, number of mummies, fetal space, and fetal survival. Data were analyzed using a model that included the fixed effects of PRLR genotype, parity, breed, and all significant two-way interactions. For several traits, fixed effect of horn was added to the model to determine the presence of between horn effects. PRLR genotype was found to influence (P < 0.10) number of fetuses per horn, average fetal weight, and total fetal weight. For each of these traits, allele 2 conferred a performance advantage over allele 1. Animals with the 22 genotype had a larger (P < 0.10) average fetal weight per horn and number of fetuses per horn (0.815 ± 0.015 lbs, 5.41 ± 0.2) than animals with the 11 genotype (0.767 ± 0.021 lbs, 4.81 ± 0.3). The PRLR genotype also displayed a favorable, but statistically nonsignificant, trend with respect to fetal survival. The PRLR gene is favorably associated with several reproductive tract traits and is in agreement with previous research for litter size. A patent has been issued to Iowa State University for the use of this gene to improve reproductive traits in swine.