2004 Volume 75 Issue 3 Pages 353-361
Comparisons of breeding stock among the Japanese Black cattle across regions were impeded because breeding programs and genetic evaluations were carried out primarily within regions. A nationwide connectedness was missing. The objective of this study was to investigate the possibility of a national genetic evaluation of breeding stocks based on appropriate mathematical models and suited material. Goodness of fit of the models was measured by the prediction error variance, the Akaike’s information criterion and coefficient of determination. The data consisted of field records on carcass traits (beef marbling standard number, BMS No. ; carcass weight, CW ; rib-eye area, REA ; rib thickness, RT ; subcutaneous fat thickness, SFT) of fattened Japanese Black cattle collected from 1997 to 2002 among the nationwide fattening farms of Agura Kyosai Bokujo, Inc. (N=49,810). The pedigree of those animals was surveyed, too. More than 95% of all possible pairs of fattening farms have beef animals with common sires. Further beef animals from different prefectures were dispersed over fattening farms so that comparisons among all prefectures were possible. Six mathematical models were applied, which differed in the way how each of the fixed effects was taken into account. The estimated heritabilities do not vary significantly among the applied mathematical models (h2 for BMS No. : 0.43 ; CW : 0.45-0.49 ; REA : 0.32-0.33 ; RT : 0.31-0.33 ; SFT : 0.46-0.47). The models with the best goodness of fit are obtained when all the fixed effects are taken into account as a combination effect or when all the fixed effects but the effect of sex are taken into account as a combination of them. We were able to demonstrate that the genetic connectedness among subpopulations is sufficient in the involved fattening farms in order to establish a genetic evaluation on a national scale. A nationwide evaluation of the Japanese Black breeding stocks will enhance the genetic improvement of the breed by a more efficient selection of excellent sires and dams.
