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Myogenic factor 5 (Myf5) and POU class 1 homeobox 1 (POU1F1) genes play important roles in growth and development of mammals. Bovine Myf5 and POU1F1 were characterized to detect genetic variation at these loci and to replace them to economic traits in 367 cattle representing Hanwoo (325) and Angus (37). Two single nucleotide polymorphisms (SNPs) were identified in intron 2 (A1948G SNP) of Myf5 and exon 6 (A15635G SNP) of POU1F1 by sequence analyses of genomic DNA. Statistical analysis indicated that the Myf5 polymorphisms significantly (0.05) associated backfat thickness and live weight at 6-months-of-age and that POU1F1 polymorphisms significantly influenced carcass weight and live weight at 24-month of age, and backfat thickness. The interaction between Myf5 and POU1F1 was significant on carcass weight, M. longissimus dorsi area, backfat thickness and marbling score. The results implicate Myf5 and POU1F1 as candidate genes of growth and carcass traits, and suggest that the interaction between Myf5 and POU1F1 strongly affect growth and carcass traits in cattle.

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Carcass characteristics of 241 crossbred pigs (Korean wild boars × Landrace sows) were analyzed to examine variations in fasted body weight (FASTWT), carcass weight (CARCWT), dressing percentage (DP), back fat thickness (BFT) and longissimus muscle weight (LMW), and to estimate genetic and phenotypic parameters using three different slaughter-end points. Covariates in the least squares full sib model were slaughter age, fasted body weight and back fat thickness of the carcass. Coefficient of variation was highest for BFT followed by LMW, CARCWT, FASTWT and DP in magnitude. Regressions of three covariates on traits were all linear. However, slaughter age was not significant as a linear covariate for five traits while FASTWT was significant for CARCWT and LMW and BFT was significant for all remaining traits. Genetic and phenotypic variation was considerably reduced by regressing FASTWT or BFT in the model. Heritability estimates of FASTWT, CARCWT, DP and BFT were 0.68, 0.61, 0.11 and 0.49, respectively, using slaughter age as covariate (model 1). Those of CARCWT, DP, BFT and LMW were 0.15, 0.15, 0.30 and 0.11, respectively, using FASTWT as covariate (model 2). Heritability estimates of the traits using LMW as covariate (model 3) were similar to the estimates from Model 1 except that the estimate of CARCWT was reduced to 0.39. Genetic or phenotypic correlations among FASTWT, CARCWT and BFT were all positive and moderate to high. Those between BFT and LMW were also positive and low to moderate. However, genetic and phenotypic correlations between DP and CARCWT were positive while those between DP and FASTWT were negative. It was suggested from this study that differences in carcass yield traits be determined using slaughter age or back fat thickness as slaughter-end point and carcass quality traits using fasted body weight as slaughter-end point.

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