GENETIC ASSOCIATIONS OF SOW LONGEVITY WITH AVERAGE DAILY GAIN AND BACKFAT THICKNESS

Abstract

Data collected from 2,865 removed sows (1,706 Landrace and 1,159 Yorkshire) in a Thai swine breeding herd from 2008 to 2013 were used to estimate the heritability and genetic correlations among sow longevity, average daily gain, and backfat thickness. Sow longevity was determined as the number of days from first farrowing to removal dates. Estimation of variance and covariance components were carried out with multiple – trait animal models using restricted maximum likelihood (REML) method. The variance and covariance components were used to calculate genetic parameters of all traits. The average sow longevity, average daily gain, and backfat thickness were 633 days, 863 g/day and 11.8 mm for Landrace; 579 days, 805 g/day and 10.7 mm for Yorkshire, respectively. Heritability estimates of sow longevity, average daily gain, and backfat thickness were 0.15 ± 0.03, 0.31 ± 0.05 and 0.57 ± 0.07 for Landrace and 0.11 ± 0.03, 0.23 ± 0.05 and 0.46 ± 0.07 for Yorkshire, respectively. Sow longevity unfavorably genetically correlated with average daily gain (-0.27 ± 0.12 in Landrace and -0.36 ± 0.15 in Yorkshire) and with backfat thickness (0.24 ± 0.10 in Landrace and 0.30 ± 0.13 in Yorkshire). Average daily gain genetically correlated favorably with backfat thickness only in Landrace (-0.21 ± 0.10). Although genetic correlation between average daily gain and backfat thickness in Yorkshire tended to be favorable, it was not significantly different from zero (-0.18 ± 0.12). The results revealed that the heritability estimates would be possible to be selected for sow longevity. However, the selection for high average daily gain or low backfat thickness may result in decreased sow longevity. Besides, it was possible to select for average daily gain without adversely affecting backfat thickness and vice versa. Although sow longevity was lowly heritable, it contributed to high economic importance. Thus, sow longevity should be considered to use as a selection criterion in breeding program.