Bayesian analysis of lifetime performance and prolificacy in Landrace sows using a linear mixed model with censoring

Factors affecting variation of length of productive life (LPL) and lifetime prolificacy (LTP) in Landrace sows were investigated. Herd life and prolificacy records were from 2616 daughters of 301 sires born in a nucleus herd between 1990 and 1996. Records from sows sold to other farms for production purposes were treated as randomly censored. Factors studied were year-season of herd entry, age at herd entry, litter size at first parity (for LPL) and sire of the sow. Additional censoring rates of 25 and 35% were created to assess influence of censoring on inferences. LPL, log(LPL) and UP were analyzed using a linear mixed model with censoring. Age at herd entry did not affect the traits studied. Sows with smaller litters at first parity had a higher risk of being culled. Posterior means of heritability of LTP, LPL and log-LPL were 0.22-0.25. Intra-trait correlations between sire evaluations at the three censoring rates ranged between 0.69 and 0.96. Estimates of sire transmitting abilities obtained with censored records removed from the analysis were in less agreement with evaluations obtained with the actual data set than those found with the artificial censoring rates. (C) 2001 Elsevier Science BY. All rights reserved.