Swine

Genetic correlations between sow uterine prolapse and reproductive traits using first- and multiple-parity performance data

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Abstract

Sow mortality is a trait of both welfare and economic importance. Elevated sow mortality reduces the effective breeding population, increases management and replacement costs, and places a psychological burden on the farmer. Furthermore, mortality might be associated with reduced animal welfare. Consequently, maintaining low sow mortality is essential for sustainable pig production. One notable contributor to sow mortality is vaginal/uterine prolapse (PLS), defined as a loss of pelvic support that results in protrusion of the vagina or uterus. Because many breeding programs emphasize selection based on early reproductive performance, we hypothesized that selecting only on first-parity records could inadvertently increase the incidence of PLS. This study quantified the genetic relationship between PLS and reproductive performance in a purebred maternal line, contrasting models based on first-parity information with models that used lifetime performance. Data were available for 38,175 sows from multiple farms between 2014 and 2024. Records included PLS (average incidence of 4.4% across parities), total number born (TNB), number of stillborn piglets (SB), body condition score at weaning (BCS), and sow longevity. Longevity was defined as retention to parity 2 (LGY2) or to parity 5 (LGY5). Genetic parameters were estimated using ASReml-R with a pedigree of 41,025 individuals. Reproductive traits were defined using either lifetime performance (TNBAll, SBAll, BCSAll) or first parity performance (TNB1, SB1, BCS1). On the observed scale, the heritability of PLS was 0.13, indicating genetic variation in susceptibility to PLS and validating our current breeding strategy that includes explicit selection against PLS. The genetic correlations (r_g) between TNB1 and PLS was essentially zero, suggesting little to no relationship. However, a negative (favorable) correlation (r_g= −0.16) was observed between TNBAll and PLS, indicating that higher lifetime TNB is associated with lower PLS. A similar relationship was observed with longevity, where enhanced longevity to parity 5 (-0.22) was associated with reduced PLS. In contrast, correlations between SB and BCS with PLS were small and stable regardless of definition (SBAll = 0.18 vs. SB1 = 0.19; BCSAll = −0.10 vs. BCS1 = −0.08), implying a consistent genetic relationship with PLS. In conclusion, the results suggest that selection for higher TNB using lifetime performance information, rather than first-parity data only, may reduce the genetic susceptibility to PLS as a correlated response. Furthermore, the results indicate that restricting selection to first-parity reproductive performance may mask unfavorable genetic associations with PLS and, over time, could increase its incidence. Incorporating all-parity information offers the possibility of selection strategies that can simultaneously reduce PLS while maintaining good reproductive performance, improving lifetime productivity, and reducing prolapse-related mortality.

Keywords: 2026

How to Cite:

Tabet, J., Leite, N., Priem, I., Martinez, G., Dunkelberger, J. & Grindflek, E., (2026) “Genetic correlations between sow uterine prolapse and reproductive traits using first- and multiple-parity performance data”, World Congress on Genetics Applied to Livestock Production Digital Archive 2026(1): 2285725. doi: https://doi.org/10.31274/wcgalp.23783

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