• Asian-Australasian Journal of Animal Sciences
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• v.12 no.4
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• pp.506-510
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• 1999

A study was made of the effects of genetic and environmental factors on ultrasonic estimates of carcass traits of Japanese Brown cows. The M. longissimus thoracis area (MLTA), Subcutaneous (SFT) and Inter Muscular (IMFT) Fat Thickness, Rib Thickness (RT) and Beef Marbling Score (BMS) were scanned at the $7^th$ rib by ultrasound. Significant differences between sires, raising place, birth year and season were found for all traits. The heritabilities estimates for sire or Maternal Grand Sire (MGS) on ultrasonic estimates of carcass traits ranged from 0.05~0.14. Genetic and phenotypic correlations among the ultrasonic estimates were positive (0.13~0.88 and 0.24~0.75). Raising place effects were significant for all traits and the differences were between $30.8{\sim}33.5cm^2$ for MLTA and 0.46~0.67 for BMS. Cows born in 1988 tended to have high MLTA, SFT, IMFT and RT but low BMS. Cows born in spring tended to have high MLTA. Cows born in winter or autumn tended to have high BMS. The interaction effects of birth year with birth season were significant for both. MLTA and BMS.

• Asian-Australasian Journal of Animal Sciences
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• v.20 no.11
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• pp.1631-1635
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• 2007

Japanese Brown cattle, one of the four domestic beef breeds in Japan, are suffering from numerical reduction due to economic pressure from profitable breeds. In this study, all the reproductive cows in the Kouchi sub-breed of the Japanese Brown cattle that were alive in July 2005 were investigated by pedigree analysis to clarify genetic structure and composition of genetic variability. In addition, genetically important individuals for the maintenance of genetic variability of the sub-breed were also identified through the core set method. The number of cows analyzed was 1,349. Their pedigrees were traced back to ancestors born around 1940, and pedigree records of 13,157 animals were used for the analysis. Principal component analysis was performed on the relationship matrix of the cows, and their factor loadings were plotted on a three-dimensional diagram. According to their spatial positions in the diagram, all the cows were subdivided into five genetically distinctive subpopulations of 131 to 437 animals. Genetic diversity of the whole sub-breed, which is estimated to be 0.901, was decomposed into 0.856 and 0.045 of within-subpopulation and between-subpopulation components. Recalculation of genetic diversity after removal of one or several subpopulations from the five subpopulations suggested that three of them were genetically important for the maintenance of genetic variability of the sub-breed. Applying the core set method to all the cows, maximum attainable genetic diversity was estimated to be 0.949, and optimal genetic contributions assigned to each cow supported the previous results indicating relative importance of the three subpopulations as useful genetic materials.