Does lameness in the sow influence her reproduction?

Thu Le Hong^a, Elise Norberg^b, Nils Lundeheim^a

^aDepartment of Animal Breeding and Genetics, Swedish university of Agricultural Sciences, Sweden;  ^bDepartment of Molecular Biology and Genetics Aarhus University, Denmark

Lameness is not only a welfare issue but also a major source of economic loss in pig production. Lame sows are assumed to suffer from pain and stress which might cause negative effects on her reproduction. Our aim was to estimate the genetic association between leg scoring (performed at performance testing, at approx. 100 kg live weight) and reproductive performance of the sows.

Data analyzed consists of records on purebred Swedish Yorkshire pigs born and raised in nucleus herds. In total 119345 pigs were tested for two lameness traits: movement (MOV) and overall leg score (LEG). Both scores of MOV and LEG ranged from 1 (worst) to 3 (best) and were transformed using normal score transformation to obtain normality. Information on fertility in first parity (in total 13048 sows) included gestation length (GES), number of total and alive born piglets (TOT and LIV), weaning to service interval (within 7 days after weaning; WSI7), and litter weight at 3 weeks of age (wLIT). The DMU package using bi-variate and multitrait animal models was used to perform the genetic analyses.

As expected, the two lameness traits (MOV and LEG) were highly correlated with a genetic correlation of 0.88±0.02. Due to relatively high standard error, correlation between lameness traits and reproductive traits in the first parity were not significantly different from 0. Lameness traits and WSI7 seem negatively correlated (r_g=-0.33±0.21), meaning that sows with worse score of lameness tend to have longer weaning to service interval. In order to have a better conclusion about genetic association between lameness of the sow and her reproduction performance, further studies, including information on later parities will be performed.