Reproductive performance of crossbred and purebred dairy cows

Analysis of 3095 records from purebred and crossbred dairy cows at five research stations of Agriculture Canada showed that the additive, maternal, and heterosis effects on kind of birth, placental condition, and percent of male or female dead calves were of minor importance. In 3108 records of purebred cows, the number of dead calves did not depend on whether or not the calf was purebred or crossbred or if it was born in first, second, third, or fourth lactation. However, 3080 records from cows of Holstein and Ayrshire lines and crossbred cows resulting from crossing the two lines gave results of higher mortalities of Holstein calves than of Ayshire or crossbred cows. Means of days to first service, number of services per conception, calving interval, and gestation period were almost idential for each genetic group of cows.