Correlations between microsatellite DNA heterozygosity and reproductive traits in Large White sows

The main aim of this paper was to determine whether heterozygosity (assessed using microsatellite genotypes) was correlated with the reproductive traits in sows. The study was conducted on two herds of sows of the Large White sows breed at the Limited Liability Company “Tavriys’ki svyni” (Kherson region, Ukraine) and the Agricultural Private Enterprise “Techmet-Yug” (Mykolayiv region, Ukraine). During the study, we used eleven microsatellite loci recommended by International Society for Animal Genetics (ISAG) – S0101, S0155, S0228, S0355, S0386, Sw24, Sw72, Sw240, Sw857, Sw936 and Sw951. The litter records included information on the total number of piglets born (TNB), number of piglets born alive (NBA), number of stillborn piglets (NSB), frequency of stillborn piglets (FSB), litter size at weaning (NW) in the first five parities. Individual heterozygosity estimates (for each microsatellite loci separately) and microsatellite multilocus heterozygosity (for all used loci) estimates (MLH) were used in our analysis. ANOVA was used to determine the relationship of the dependent effects (reproductive traits) to single locus heterozygosity using two classes: 0 (for homozygous individuals) and 1 (for heterozygous individuals). In addition, the following indicators were calculated for each genotype: the squared distances (d2) between alleles within an individual for each microsatellite loci and mean squared distances (mean d2) between alleles within an individual for 11 microsatellite loci. Spearman’s rank correlation coefficients were used to measure the association between d2 (for each microsatellite loci) and reproductive traits in sows. ANOVA on reproductive traits of sows belonging to different MLH and mean d2 classes was also undertaken. For sows from the Agricultural Private Enterprise “‘Techmet-Yug” were observed negative associations between heterozygosity and reproductive traits. We conclude that care should be taken when crossing between different breeders (English and Hungarian selection) to avoid outbreeding depression.