Genetic parameters and genetic trends in the Chinese x European Tiameslan composite pig line. I. Genetic parameters

Genetic parameters of body weight at 4 (W4w), 8 (W8w) and 22 (W22w) weeks o f age, days from 20 to 100 kg (DT), average backfat thickness at 100 kg (AB T), teat number (TEAT), number of good teats (GTEAT), total number of pigle ts born (TNB), born alive (NBA) and weaned (NW) per litter, and birth to we aning survival rate (SURV) were estimated in the Chinese x European Tiamesl an composite line using restricted maximum likelihood methodology applied t o a multiple trait animal model. Performance data from a total of 4 881 mal es and 4 799 females from 1 341 litters were analysed. Different models wer e fitted to the data in order to estimate the importance of maternal effect s on production traits, as well as genetic correlations between male and fe male performance. The results showed the existence of significant maternal effects on W4w, W8w and ABT and of variance heterogeneity between sexes for W22w, DT, ABT and GTEAT. Genetic correlations between sexes were 0.79, 0.7 1 and 0.82, respectively, for W22w, DT and ABT and above 0.90 for the other traits. Heritability estimates were larger than (ABT and TEAT) or similar to (other traits) average literature values. Some genetic antagonism was ev idenced between production traits, particularly W4w, W8w and ABT, and repro ductive traits.