324 Genetic parameters for sow longevity traits in purebred and crossbred maternal line pig populations.

Abstract Breeding for improved sow longevity will contribute to directly improving animal welfare, production efficiency, and environmental sustainability in the swine industry. Sow longevity is a complex trait that can be defined by different indicators, including length of productive life (LPL), removal age (RA), and removal parity (RP). Genetic selection for improved sow longevity is also more challenging due to the time taken for obtaining the phenotypic measurements for each animal, censored nature of the records due to voluntary culling, and potential genotype-by-environment interactions between nucleus and commercial farm conditions. Therefore, the primary objectives of this study were to estimate variance components and genetic parameters for LPL, RA, and RP in purebred and crossbred pig populations incorporating genomic information in the analyses. Data from 26,441 sows were analyzed, including 14,787 Landrace and 11,654 Landrace x Large White crossbreed sows. Pedigree and genotype data were incorporated into the analyses, including information from 5,378,363 animals in the pedigree and 22,925 genotyped animals. Variance components and genetic parameters were estimated using the Restricted Maximum Likelihood (REML) method implemented in the BLUPF90+ software. The fixed effects included in the models were contemporary group (concatenation of herd, season, and year of birth) and age at first parity as a linear covariate. For the analyses combining purebred and crossbred animals, line was also added as a fixed effect. The average (SD) LPL was 242.10 (242.22) days for Landrace and 352.56 (289.29) days for the crossbred sows, with maximum values of 1,592 and 1,258 days, respectively. The average (SD) RA was 587.50 (241.89) days for Landrace and 674.60 (291.78) days for the crossbred sows. A total of 81.32% of the sows, considering both purebred and crossbred animals, were removed by the fourth parity. The heritability estimates for the Landrace sows were 0.20 (0.02) for LPL and RA, and 0.22 (0.02) for RP. For the crossbred population, the heritability estimates were 0.11 (0.02) for all three traits. For the complete dataset (i.e., combining both lines), the heritability (SE) estimates were 0.28 (0.02) for LPL and RA, and 0.30 (0.02) for RP and the genetic correlation between LPL and RP, as well as between RA and RP, was 0.99 (0.0003). The observed heritability estimates suggest that genetic selection can effectively improve sow longevity. Additionally, the high genetic correlation (0.99) between them indicates that these traits are essentially the same from a genetic perspective. This suggests that only one of them may be needed as selection criteria.