Comparison of evaluations for production traits of Holstein bulls among Canada, the United States, and Japan
Based on Multi-trait Across Country Evaluation (MACE), genetic correlations and international evaluations were calculated among Canada, the United States and Japan to assess the impact of upgrading by importing genetics in Japan, to identify top ranked bulls in Japan, and to determine the effect of imported semen on international evaluation. Future improvement of the Japanese progeny test program is also discussed. The estimated genetic correlation estimates between Japan and North America were high, and exchanging dairy genetics would enhance genetic improvement of these countries if the imported animals are selected properly. Comparison of genetic trends verified that Japanese artificial insemination (AI) centres have successfully upgraded their bulls after their initiation of a national progeny test program. However, the number of Japanese bulls ranked in the top 100 was not so much. Increasing the number of young bulls tested each year could enhance the position of Japanese bulls.