Sire evaluation for milkability traits in Swiss Braunvieh

Cows were tested for milkability with standardized milking equipment. Percentage of milk from the forequarters (FQ%), average milk flow rate (AMF) in kg min^?1, quantity of hand-stripped milk (HSM) and milk yield at test day (MTD) were recorded. Records of 10 823 daughters in the first lactation of 352 sires were used to investigate environmental influences and to estimate genetic parameters. Significant effects were test season and herd production level for AMF and HSM, test person, milking equipment on the farm, month in lactation, age at calving and region for FQ%, AMF and HSM. The heritabilities were 0.34 for FQ%, 0.41 for AMF and 0.10 for HSM. The genetic correlations of MTD were 0.13 with FQ%, 0.23 with AMF and ?0.20 with HSM. The genetic correlations between FQ% and AMF and all genetic correlations with HSM were negative. Selection indices with information on average deviations of daughters' MTD, FQ%, AMF and HSM from corresponding region — herd level — season means and different economic weights were used to predict selection indices for 239 sires. The predicted breeding values were compared with simple daughter averages. The correlations were high, but large differences in ranks occurred for individual sires. Correcting AMF for milk yield removes some genetic variation in milk flow and can mask genetic differences between sires.