A genome-wide linkage analysis for reproductive traits in F2 Large White × Meishan cross gilts.

C. S. Haley,C. J. Ashworth,H. A. Finlayson,A. L. Archibald,S. C. Hernandez

doi:10.1111/age.12123

Abstract

Female reproductive performance traits in pigs have low heritabilities thus limiting improvement through traditional selective breeding programmes. However, there is substantial genetic variation found between pig breeds with the Chinese Meishan being one of the most prolific pig breeds known. In this study, three cohorts of Large White × Meishan F2 cross-bred pigs were analysed to identify quantitative trait loci (QTL) with effects on reproductive traits, including ovulation rate, teat number, litter size, total born alive and prenatal survival. A total of 307 individuals were genotyped for 174 genetic markers across the genome. The genome-wide analysis of the trait-recorded F2 gilts in their first parity/litter revealed one QTL for teat number significant at the genome level and a total of 12 QTL, which are significant at the chromosome-wide level, for: litter size (three QTL), total born alive (two QTL), ovulation rate (four QTL), prenatal survival (one QTL) and teat number (two QTL). Further support for eight of these QTL is provided by results from other studies. Four of these 12 QTL were mapped for the first time in this study: on SSC15 for ovulation rate and on SSC18 for teat number, ovulation rate and litter size.

Highlights

Reproduction, especially female reproductive performance, is an important component in livestock production
A fixed quantitative trait loci (QTL) allele model, in which genetically distinct founder lines (MS and Large White (LW) pigs in this case) were assumed to be fixed for alternative alleles at the QTL affecting the trait of interest, was used for the QTL scan analyses (Haley et al 1994)
For all QTL analyses, gestation length was included as a covariate, except for Teat number (TN) for which no covariate was used

Summary

Introduction

Reproduction, especially female reproductive performance, is an important component in livestock production. Selection for improved prolificacy over the last decade has been performed in different countries with a consequent moderate increase in litter size (LS) at birth (Bee 2007). This increase in number of piglets at birth has led to an increased within-litter variation in birthweight as well as a decrease in the birthweight per piglet (Bee 2007).

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Conclusion