Conclusions
The PRLR gene is associated with several reproductive tract traits. In our population, allele 2 of the PRLR gene has a favorable effect on average fetal weight, total fetal weight, fetal weight per horn, number of fetuses per horn, and average fetal weight per horn. The increased performance of females with more copies of allele 2 may be due to the effect of the locus on survival of fetuses from fertilization to day 75 of gestation.
The addition of more animals to this study in the future will help validate and explain the significance of these results.
References
Bole-Feysot, C., V. Goffin, M. Edery, N. Binart, and P.A. Kelly. 1998. Prolactin (PRL) and its receptor: actions, signal transduction pathways and phenotypes observed in PRL receptor knockout mice. Endocrine Reviews 19:225.
Farmer, C., M.F. Palin, and M.F. Sorensen. 2000. Mammary gland development and hormone levels in pregnant Upton-Meishan and Large White gilts. Domestic Animal Endocrinology 18:241.
King, R.H., J.E. Pettigrew, J.P. McNamara, J.P. McMurty, T.L. Henderson, M.R. Hathaway, and A.F. Sower. 1996. The effect of exogenous prolactin on lactation performance of first-litter sows given protein-deficient diets during the first pregnancy. Animal Reproduction Science 41:37.
Vincent, A.L., G. Evans, T. Short, O.I. Southwood, G.S. Plastow, C.K. Tuggle, and M.F. Rothschild. 1998. The prolactin receptor is associated with increased litter size in pigs. Proceedings of the 6th World Congress on Genetics Applied to Livestock Production. 27:15.