Relationships between piglet survival and breeding values for dry-cured ham production

Logistic regression and survival analysis were used for investigating the relationship between piglet survival at birth (SB) or from birth to weaning (SBW), and breeding value class of the piglet (n=11089; Large White Gorzagri C21 boar line) for live weight at 270 d (LW270), for raw ham traits (round shape, fat thickness and marbling), and for backfat. Effects of sex, parity of the nurse sow or dam, year, season, cross-fostering, size of born or nursed litter (NL), and piglet total merit selection index (TMI) were also considered. SB was not affected by sex, size of the born litter, and by breeding values of the piglet, but year and season of birth and parity of the sow were significant risk factors. Cross-fostering (Hazard ratio = 0.39, Odds ratio = 0.81, P<0.01) increased SBW whereas a size of NL greater than 12 decreased SBV (Hazard ratio = 6.76, Odds ratio = 7.96, P<0.01). For all breeding values, at least one class exhibited different risk from the reference class, but relations between top breeding value classes and piglet survival were favourable. For piglet TMI, which includes also piglet survival, significant differences between the reference class and the worst (Hazard ratio = 1.36, Odds ratio = 1.40, P<0.01) or the best TMI class (Hazard ratio = 0.59, Odds ratio = 0.58, P<0.01) were detected.