Abstract
Based on data of 3431 steers fattened by farmers in Kagoshima prefecture during 1978 and 1979, the possibilities of progeny tests on the meat production performance of Japanese Black Cattle sires were examined. Differences among the means of sire family groups were statistically significant (P<0.01), in all the following traits analyzed in this study: initial weight, age in days at the beginning of fattening, initial weight per age (body weight per day of age at the beginning of fattening), period of fattening, final weight, daily gain during the period of fattening, marbling score and rib eye area. Heritabilities of initial weight, rib eye area and marbling score were calculated to be 0.4-0.6, 0.5-0.6 and 0.3-0.5, respectively. Heritabilities of other traits were relatively low and varied from year to year. Concerning initial weight, marbling score and rib eye area, correlations between rank of sire in 1978 and in 1979 were estimated as 0.609, 0.765 and 0.767, respectively (P<0.01). Genetic correlations among the productive traits were calculated to be: marbling score and initial weight 0.40, marbling score and age in days at the beginning of fattening 0.30, marbling score and daily gain -0.35, rib eye area and period of fattening 0.45, rib eye area and marbling score 0.37, daily gain and period of fattening -0.79, and daily gain and final weight 0.81. From above results, it was recognized that a progeny test based on fattening data obtained from farmers was practicable for the valuation of a sire.
