Characterization of Follistatin as a Candidate Gene for Litter Size in Pigs

Abstract

The objective of this study was to characterize follistatin (FOL) as a candidate gene for litter size in pigs. Litter size is a lowly heritable and sex-limited trait; therefore, response to selection may be enhanced by marker-assisted selection. Our approach for characterizing a region of SSC16, which includes FOL, was to utilize the candidate gene approach using type I and type II markers to determine if FOL had an association with the response to selection for increased litter size in the select line. Pigs genotyped were from a line selected for increased number of fully formed (FF) pigs and a contemporary control line. In generation nine, the estimated breeding value for litter size was 0.63 pigs greater in the select line than in the control line (Holl et al., 2003). A RFLP within FOL (n = 251) and the microsatellites, CGT27 (n = 224), S0363 (n=255), S0298 (n=260), and SW1661 (n=253) were genotyped. Effect of marker genotype on FF, number born alive (BA), number still born (SB), and number mummified fetuses (MUM) was tested. Data were analyzed by line with an animal model using MTDFREML. Fixed effects included year and marker genotype. In both the select and control lines, all markers had no significant affect on FF, BA, SB, or MUM when using the animal model. Therefore, follistatin is not likely to have a major effect on litter size in the population studied.