Heterosis for milk production traits by crossing Red Danish, Finnish Ayrshire and Holstein-Friesian cattle

Abstract

A large experiment was initiated in Denmark in 1972 to examine benefits from systematic crossing of the dairy cattle breeds Red Danish (RD), Finnish Ayrshire (FA), Danish Friesian (DF) and Holstein-Friesian (HF). The data were analysed by three versions of a mixed model. The first included additive breed effects and F 1 heterosis (dominance model). Additionally, the second included effects of recombination (recombination model). In the third version the effects of each genetic group were estimated (group model). Means of the genetic groups predicted by the dominance and the recombination model were compared with the means estimated in the group model. The estimates of F 1 heterosis from the dominance model were 20, 6, 20 kg of fat, 18, 8, 18 kg of protein and 428, 206, 537 kg of milk for 305-days-yield records of RD × FA, FA × HF and RD × HF, respectively. The corresponding estimates from the recombination model were 22, 24, and 10 kg fat, 20, 30 and 7 kg of protein and 486, 820 and 210 kg of milk. The estimated effects of recombination were negative and eliminated the positive effect of F 1 heterosis in the later generations.