051
Assessing the effects on litter size of age of inbreeding in an ancient line of Large White pigs
Different pedigree parameters were computed from the complete genealogy of a small herd of Large White pigs, kept closed from 1931 to 1992, with 14 unrelated founders and 1,358 reproducers. The mating design was remarkably changed at 1956 to restrict the rate of inbreeding. Total inbreeding was divided into ‘old’ and ‘new’ components with respect to this year. Inbreeding depression on litter size was estimated on 1,638 records from 613 sows born after 1956 using both metrics and their rates per generation. Negative effects of a 10% of ‘new’ inbreeding were inferred (-0.45 piglets born and -0.62 piglets born alive), while the impacts of total inbreeding were less substantial (-0.28 and -0.50 piglets) or negligible relative to those of ‘old’ inbreeding. This departure of classical model suggests that, when deep pedigree exists, more accurate depression estimates may be obtained using ‘new’ inbreeding metrics.
Keywords:
Large White
new inbreeding
inbreeding depression
