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

A crossbreeding experiment using Large White (LW) and Meishan (MS) pig strains was conducted. Direct, maternal and grand-maternal additive genetic effects together with direct, maternal and paternal heterosis effects were estimated for traits during the preweaning, growing and reproductive periods. Weight at birth (WB) and at 21 d of age (W21) was recorded in 3731 male and female piglets. After weaning at 28 d, 543 females were weighed at 73 (W73) and 154 (W154) d of age. From these, 148 sows were weighed before farrowing from 1st to 5th parity. Average daily gains were computed from birth to 21 days of age (ADG 0-21), 21 to 73 days of age (ADG 21-73) and 73 to 154 days of age (ADG 73-154). The genetic influence on preweaning traits was mainly maternal in origin. Maternal additive differences between breeds significantly increased with parity of the dam. Average values were 0.33 +/- 0.05 kg (26%) and 1.24 +/- .022 kg (25%) in favour of LW for WB and W21 respectively. Maternal heterosis effects were 0.05 +/- 0.02 kg (6%) for WB and 0.65 +/- 0.09 kg (14%) for W21. Significant grand-maternal additive and direct heterosis effects were also observed on WB. Adjustment of data for litter size slightly increased additive and heterosis maternal values. After weaning, direct effects became important. Additive differences between breeds rapidly increased during the growing period and averaged 4.1 +/- 1.0 kg (18%), 22.9 +/- 3.3 kg (36%) and 231 +/- 33 g/d (47%) in favor of LW of W73, W154 and ADG 73-154 respectively. Direct heterosis effects for these traits were 3.7 +/- 0.7 kg (15%), 19.2 +/- 2.3 kg (25%) and 187 +/- 24 g/d (30%) respectively. Direct additive differences in favour of LW increased from 58 +/- 9 kg at the first farrowing to 111 +/- kg at the fifth one. Direct heterosis effects were similar throughout reproductive life and averaged 27 +/- 3 kg (11%). The other crossbreeding parameters were small and non-significant after weaning, with the exception of maternal heterosis effects, which remained significant until 154 days.