Scope for a Subjective Assessment of Milking Speed

Abstract

Farmers’ subjective evaluations of their cows’ milking speed, scored as “very fast”, “fast”, “average”, “slow”, or “very slow”, were recorded between 1982 and 1985 under Agriculture Canada's Record of Performance milk recording scheme. For the analysis, scores taken at the beginning (score 1) and the end (score 2) of the lactation were distinguished. Edited data comprised 20,909 records for score 1 and 19,012 records for score 2 for Ayrshires and 190,455 and 148,536 for Holsteins. Data were analyzed in eight subsets. The effects of herd-year-seasons (of calving), calving age, and stage of lactation when scored were evaluated and variance and covariance component estimates were obtained for sires, cows, and residuals. Heritabilities were .21 and .14 for score 1 for Holsteins and Ayrshires, respectively, and .17 and .16 for score 2. Repeatabilities were .42 and .37 for the two breeds. The scope of a sire evaluation for milking speed based on subjective scores is discussed. © 1987, American Dairy Science Association. All rights reserved.