Evaluation of pig flight time, average daily gain and backfat using random effect models including grower group

Records for flight time, average daily gain and backfat were analysed from 9,638 pigs measured between April 2004 and November 2007. Genetic parameters were estimated for the three traits using alternative animal models, fitting combinations of additive genetic, common litter and grower group effects fitted as random terms. Log likelihood ratio tests showed that all three random effects were significant for the three traits analysed. Heritability estimates were 0.15 ± 0.02 for flight time, 0.22 ± 0.03 for average daily gain and 0.40 ± 0.04 for backfat. Estimates for common litter (c²) and grower group (g²) effects were small (0.02 to 0.05) for flight time and backfat. Conversely, for growth rate estimates of c² and g² were 0.08 ± 0.01 and 0.17 ± 0.01, respectively. It is recommended that grower group be recorded for further investigations of social genetic effects. Flight time was genetically correlated with backfat (0.21 ± 0.09) but had no significant genetic relationship with growth rate (0.14 ± 0.11). Overall, little correlated response is expected in flight time resulting from selection for higher growth and lower backfat.