collected from approximately 1100 purebred Duroc pigs between 2011 and 2017. The meat quality traits evaluated were: moisture content (MC), fat content (FC), water holding capacity (WHC), cooking loss (CL), and shear force (SF). Meat samples were evaluated for the following fatty acids: palmitic, stearic, oleic, linoleic, and linolenic acids. We evaluated the meat for the following sensory traits: color, flavor, tenderness, juiciness, and acceptability of the meat. Variance and covariance components were estimated using restricted maximum likelihood procedures on different animal models. The results showed that the estimates of heritability for MC, FC, WHC, CL, and SF were 0.17, 0.58, 0.34, 0.31, and 0.42, respectively. The heritability estimates for fatty acid composition were moderate to high (0.34 to 0.63). The estimates of genetic correlation were -0.60 and 0.46 between MC and FC, and MC and SF, respectively. Generally, phenotypic correlation between meat quality traits was low. Linoleic acid had moderate to high negative phenotypic and genotypic correlation with both palmitic and oleic acid. Comparison of meat quality traits and sensory traits revealed a positive correlation (0.208) between acceptability and WHC, while the correlation between acceptability and SF was negative (-0.207). The estimated genetic parameters among meat quality traits, sensory traits, and fatty acid composition in this study are expected to be used to improve pork to suit consumer preferences.

The objective of this study was to estimate the effects of test seasons on backfat thickness and age at 90 kg body weight in Duroc pig populations. Data of a total of 40,228 Duroc pigs performance tested from 2005 to 2014 were used. The effects of sexes, years and seasons of the tests were significant (p<0.01) for the both traits. The least squares mean of the age at 90 kg body weight of the pigs tested in 2014 was significantly less than that of the pigs tested in the previous years. And the pigs tested in spring reached 90 kg body weight faster than the pigs tested in the other seasons. The least squares mean of backfat thickness of the pigs tested in autumn was thicker than that of the pigs tested in the other seasons. Pigs tested in spring had the thinnest backfat. There were seasonal variations in the least squares mean estimates of the age at 90 ㎏ both in male pigs (134.06 to 134.36 days), and in female pigs (139.47 to 139.65 days). Seasonal variations were also detected in least sqaures means of the backfat thicknesses in male pigs (11.31-11.34 ㎜) and in female pigs (13.05-13.07 ㎜). The simple and rank correlation coefficients between breeding values estimated using the trait values unadjusted for seasonal effects and those using the trait values pre-adjusted for seasonal effects trait values were all unity, for the both traits. These results indicate that the adjustment of the trait values with regards to seasonal variation had no effects on the estimates from genetic evaluations.