68 Genomic prediction accuracies of vulva size traits in Landrace and Yorkshire gilts

Abstract

Recent results indicated that vulva size measured prior to puberty may be predictive of reproductive performance in sows. Therefore, the objective of this study was to estimate genomic prediction accuracies for vulva size traits in purebred gilts. A total of 1,185 Landrace (n = 477) and Yorkshire (n = 708) gilts originated from two different lines were used in this study. All animals had vulva size measurements taken at an average 21.5 weeks of age (SD = 5.8). Measurements included vulva width (VW), vulva height (VH), and vulva area (VA). Genotype data (Geneseek GGP-HD) was available for all animals, for ~40K SNPs. Marker allele substitution effects were estimated using Bayes-B (pi = 0.99) in a model including the fixed effects of contemporary group, line, breed (for multi-breed analysis only) and body weight (covariate), and the random effect of SNPs. Genomic prediction accuracies were estimated using three training and validation strategies: between-breed, within-breed (4 and 6 cross-validation folds for Landrace and Yorkshire, respectively), and multi-breed (10-fold cross-validation, using one-fold per breed for validation at a time). Between-breed accuracies were low and consistently negative, with -0.02, -0.10, and -0.05 in Landrace and -0.05, -0.04 and -0.03 in Yorkshire, for VW, VH, and VA, respectively. Within Landrace, these were moderate, with 0.35 (VW), 0.42 (VH), and 0.56 (VA), whereas lower accuracies were obtained for Yorkshire, with 0.07 (VW), 0.20 (VH), and 0.14 (VA). Multi-breed accuracies were low with 0.14 (VW), 0.14 (VH), and 0.24 (VA) for Landrace, and 0.03 (VW), 0.16 (VH), and 0.09 (VA) for Yorkshire. These results indicate that genomic selection for vulva size traits is possible in Landrace, but limited in Yorkshire gilts. The low between- and multi-breed results suggest that QTL for these traits are in opposite phases between breeds and/or do not segregate in both breeds. Financial support from the Iowa Pork Industry Center is appreciated.