An initial study of the economic values of dairy cattle traits in Canadian Holsteins estimated using random regression models

Abstract Text: Economic values were estimated by regressing profit, adjusted for opportunity cost, up to the end of the 4^th lactation on EBVs, using random regressions within herd-year cohort of first calving. Kilograms Fat, kg Protein, milking speed, temperament, rump and conformation all had positive economic values, whereas herd life, angularity, somatic cell score and stature had negative economic values. Both mammary system and fat percentage showed significant interactions with Housing system (Tie-stall vs Free-stall). There were significant variances for herd, year and herd-cohort. Random regressions were not statistically significant. Profit not adjusted for opportunity costs showed a significant positive regression for herd-life, as might be expected, whilst stature showed a large negative regression coefficient (economic value).

Keywords: dairy, Economic values, Milk