Interbreed Matings in Dairy Cattle. I. Yield Traits, Feed Efficiency, Type and Rate of Milking

Abstract

Performance and efficiency in 1st lactation for 88 2-breed and 49 3-breed crosses among Ayrshires [A], Brown Swiss [S] and Holsteins [H] were compared to the weighted mean of purebred contemporaries to estimate heterosis from crossbreeding. All possible combinations of 2- and 3-breed crosses were included. The sires were selected by random drawings from all bulls of the 3 breeds in regular AI [artificialinsemination]service. The 2-breed crosses had 4 to 15% heterosis for days open. AxH and SxH crosses were 8 to 10% above the parental mean for production traits but AxS showed no heterosis. Heterosis for measures of efficiency of feed utilization was about 1/2 that for production in AxH and SxH crosses but was zero in AxS crosses. In general, the estimates of heterosis for 3-breed crosses were higher than for 2-breed crosses. These were superior to the mean of the parental breeds by 13.8, 11.9, 13.8, 12.2, 9.2, 13.0, 12.9, 7.2 and 0.3% in days open in lactation, milk, fat, SNF [solids-not-fat], protein and FCM [fat corrected milk] yields, therms produced, 3 measures of efficiency and persistency of milk yields, respectively. The Ayrshires, Brown Swiss and AxS crosses were significantly below Holsteins in production and efficiency traits while AxH, SxH, and 3-breed crosses were slightly lower in yields but superior to Holsteins in fat yield and efficiency. These results indicate certain crossbred groups may have economic superiority over purebreds. Rates of milking and type scores showed little evidence of heterosis.