Genetic parameters of being a tail-biting recipient in pigs

This study aimed to estimate the heritability of being a tail-biting recipient and to evaluate the genetic associations with performance traits in pigs. Tail bite lesions were recorded weekly from weaning until finisher test (TBPW) and as a single observation at finisher test, with an average age of 147 days (TBFT) on 13,458 pigs from 6 genetic lines between August 2022 and December 2023. Genetic analysis was carried out using linear and binomial animal models. Three models were investigated: fitting the direct genetic effects (M1), fitting common litter (M2), and the line group effects (M3) as additional random effects. The heritability for TBPW was 0.13 ± 0.02 for M1 with a linear model. The heritability estimates dropped to 0.05 ± 0.01 when the litter effect (M2) and line group effects (M3) were fitted. Estimates for the proportion of variance explained by the common litter effects were 0.05 and 0.06, and the line group effects were 0.03 for TBPW. The heritability for TBFT was 0.06 ± 0.01 for M1 with a linear model. Similarly, the heritability for TBFT decreased to 0.03 ± 0.01 for M2 and M3. Heritability estimates for TBPW and TBFT for M1, based on a logit liability scale within a binomial model, were 0.18 ± 0.03 and 0.17 ± 0.04, respectively. Both tailbiting traits had no significant genetic correlations with performance traits, including average daily gain, back fat thickness, and eye muscle depth. Overall, TBPW had a higher estimate of heritability than TBFT. Thus, TBPW should be used in selection strategies of pigs to reduce tail-biting and improve pig welfare.