Estimation of genetic and crossbreeding parameters for daily milk yield of Ayrshire x Sahiwal x Ankole crossbred cows in Burundi

The pedigree of 317 cows of which 184 were controlled for milk production has been used to estimate crossbreeding parameters for daily milk yield of Ayrshire, Sahiwal and Ankole crosses in the Mahwa station. Lactating cows belonged to one of 6 different genetic groups defined on the basis of the mating system used to produce them. REML estimates of the genetic parameters were obtained with a repeated animal model using daily milk records. Estimated heritability (h(2)) and repeatability (P) were 0.27 and 0.36, respectively. The genetic group effects were used to estimate crossbreeding parameters following Dickerson's genetic model. Estimates for the additive effects for daily milk yield of Ankole, Sahiwal and Ayrshire breeds were -1.661, -0.481 and 5.221, respectively. Estimates of direct heterosis for daily milk yield for Sahiwal x Ankole, Ayrshire x Ankole, and Ayrshire x Sahiwal crosses were 1.971. 2.301 and -2.331, respectively. (C) 2008 Elsevier B.V. All rights reserved