Reproductive Performance of Crossbred and Purebred Dairy Cows

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Abstract
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 Ayrshire or crossbred cows. Holstein cows also had more abnormal births than cows in other genetic groups. Placental condition did not vary among the genetic groups of cows. Rebreeding rate, defined as percentage of cows pregnant for the second time based on the number of heifers calving for the first time, less the number of heifers culled for reasons other than reproduction, was 88% for Holstein and crossbred cows and 78% for Ayrshire cows. Reduction of cows in the herds from first to third lactation was the same for Holstein and crossbred cows (63%) but 77% for Ayrshires. Means of days to first service, number of services per conception, calving interval, and gestation period were almost identical for each genetic group of cows.
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