Genetic parameters of various sow longevity traits considering culling reasons in purebred and crossbred maternal-line pig populations.

Sow longevity is a key trait in pig production, with direct implications for economic efficiency, animal welfare, and sustainability of the sector. The main objectives of this study were to characterize removal reasons in purebred and crossbred sow populations and estimate genetic parameters for three longevity indicators: length of productive life (LPL), removal age (RA), and removal parity (RP), in purebred Landrace and crossbred Landrace × Large White pig populations. Phenotypic records from 26,441 sows were analyzed under scenarios, including voluntary (age and genetic), involuntary (feet and legs, health issues, prolapse, reproduction, and sudden death), and unclassified (other and unknown) culling reasons. Pedigree information from 5,378,363 animals and genomic data from 22,925 genotyped animals were included. Variance components and genetic parameters were estimated using single-step GREML. Involuntary removals were proportionally higher in crossbred sows, mainly due to reproductive and health problems, whereas purebred sows were more frequently culled for voluntary reasons such as genetic merit or age, reflecting differences between nucleus and commercial herds. Heritability estimates of sow longevity traits ranged from 0.06 ± 0.01 to 0.30 ± 0.01, with higher values observed when combining purebred and crossbred data. RP showed a strong genetic correlation with both LPL and RA (≈ 0.99), indicating a shared genetic background. Longevity based on prolapse-related culling was moderately heritable (0.28 ± 0.06), while longevity defined by reproductive failures showed near zero heritability. Heritability estimates were low for feet and leg removals (0.08 ± 0.03), health issues (0.11 ± 0.03), and sudden death (0.06 ± 0.17). Genetic correlations between purebred and crossbred longevity were low when considering all removal reasons but increased when restricted to involuntary culling. These results indicate strong genotype-by-environment interactions for sow longevity in nucleus purebred and commercial crossbred herds. Sow longevity is heritable with substantial additive genetic variation. These results reinforce the importance of recording culling reasons in both purebred and crossbred farms and the inclusion of crossbred data in genetic analyses to optimize genetic improvement for sow longevity.