A genetic study of longevity in swine /

Data from the Quebec swine breeding program (1980 to 2001) were used to estimate genetic parameters for longevity and to evaluate the contribution of non-genetic factors. After data verifications, there were 28,377 Yorkshire, 30,123 Landrace and 7,830 Duroc sows with records of herd life. The program 'The Survival Kit V3.12' (Ducrocq and Solkner, 2001) was used to estimate heritability separately within each breed, using a Cox proportional hazard model. The time-independent fixed effects of age at first service and of the combinations of herd with year of birth, estimated breeding value (EBV) backfat, EBV age to 100 kilograms and EBV litter size were included. The effects of number of piglets born, number of piglets weaned, crossbreeding at insemination, stage of sow (farrowing, weaning or heat) and their combination with parity were treated as fixed time-dependent variables whereas herd by year was treated as random time-dependent variable. The random effect of sire using sire relationships back two generations was considered as the source of genetic variation. Length of productive life (longevity) was defined as the number of days from first service until culling