Estimation of crossbreeding parameters between Large White and Meishan porcine breeds. II. Growth before weaning and growth of females during the growing and reproductive periods

Abstract

Data on 12 genetic types (F1, F2 and reciprocal backcrosses) of Large White (LW) x Meishan pigs were analysed to estimate direct, maternal and grandmaternal additive genetic effects and direct, maternal and paternal heterosis efects for body weights during the preweaning (records on 3731 male and female pigs), growing (543 females ) and reproductive (148 sows) periods. The genetic influence on preweaning traits was mainly maternal in origin. Maternal additive differences between breeds increased significantly with parity, the av. difference being 0.33 plus or minus 0.5 (26%) and 1.22 plus or minus 0.22 kg (26%) in favour of LW for birth weight and weight at 21 days resp. Corresponding maternal heterosis effects were 0.05 plus or minus 0.02 kg (6%) and 0.65 plus or minus 0.9 kg (14%). For birth weight, grandmaternal additive effects and direct heterosis effects were significant. Direct effects increased in importance during the growing period, the additive difference between breeds averaging 4.1 plus or minus 1.0 kg (18%), 22.9 plus or minus 3.3 kg (36%) and 231 plus or minus 33 g per day in favour of LW for weights at 73 and 154 days and av. daily gain from 73 to 154 days resp. The corresponding direct heterosis effects were 3.7 plus or minus 0.7 kg (15%), 19.2 plus or minus 2.3 kg (25%) and 187 plus or minus 24 g (30%). During the reproductive period, the direct additive effects in favour of LW was 58 plus or minus 9 kg at the 1st farrowing; this increased with parity to 111 plus or minus 10 kg at the 5th farrowing. Direct heterosis effects averaged 27 plus or minus 3 kg (11%) from the 1st to 5th parity. [For Pt. 1 see Genetics, Selection, Evolution (1989) 21, 507-526].