Evaluation of current United States swine selection indexes and indexes designed for Chinese pork production

Abstract

The objective was to compare selection indexes based on the production costs and economic values from the United States and China. Indexes including terminal sire (TSI), maternal line (MLI), and sow productivity (SPI) were calculated based on the production costs and market prices for the United States and China. Estimated breeding values for days to 113.5 kg, backfat depth, loin muscle area, number born alive, number weaned, litter weight adjusted to 21 d, days from weaning to estrus, and litter birth weight were provided by a Chinese pig breeding company to evaluate alternative TSI and MLI indexes. The Duroc data included 559 dams, 39 sires, 5,079 boars, and 4,809 gilts. The Landrace data included 199 dams, 83 sires, 2,749 boars, and 2,750 gilts. The Yorkshire data included 1,368 dams, 139 sires, 18,481 boars, and 17,962 gilts. The means, SD, and correlations for the estimated breeding values and indexes were calculated. The Chinese TSI values were more highly correlated (r = 0.97 to 0.99) with the US indexes than the MLI values (r = 0.92 to 0.97). Overall, the Chinese indexes had greater SD (TSI, 58 to 87% greater; SPI, 22 to 26% greater; MLI, 43 to 76% greater). The TSI were all highly correlated (r >0.98) with feed conversion. The Chinese MLI values had greater correlations with TSI and lesser correlations with SPI than the US indexes. The Chinese MLI placed greater emphasis on the postweaning traits but less emphasis on sow productivity traits than did the current US MLI.