Effects of calf breed on milk production and other economic traits of Holstein dams.

Production of purebred or crossbred feeder calves for beef, especially HolsteinxJapanese-Black (HxJB) and Japanese-Black (JB), from dairy cattle using artificial insemination or embryo transfer have been used widely in Japan. However, dairy farmers feel uneasy about the effects of calf breed on the economic traits of dams. In this study, those effects were investigated in 798 Holstein heifers bearing Holstein, HxJB, JB or other breed calves. The results of the least-squares ANOVA indicated the effects of calf breed to be significant for gestation length (P<0.01) and calf birth weight (P<0.01) but not for milk yield, fat yield, protein yield, peak yield, day of peak, number of artificial inseminations per pregnancy or days open. Frequency of dystocia was lower in dams bearing HxJB calves than in those bearing Holstein calves (P<0.05). There were no significant differences for frequencies of still birth, retained placenta and subsequent pregnancy. The present data suggest that the effects of calf breed do not place a serious problem on the economic traits of Holstein dams. In conclusion, it is indicated that the production of JB and HxJB feeder calves from Holstein dams does not result in a decrease in dam productivity.