Genetic improvement of dairy cattle via the use of selection indices requires a knowledge of the economic values for each of the component traits. Hazel and Lush (1942) define the economic value of a trait as the improvement in profitability resulting from a unit genetic improvement in a given trait, all other traits being held constant. This corresponds to the regression of profit on Breeding Value. The Québec milk recording programme records, on a per-cow basis, milk value and feed costs for each lactation (i.e. margin over feed costs), which leads to the idea of empirically estimating economic values of traits by regressing lifetime profitability on their Estimated Breeding Values. This approach cannot be used for ‘what if’ evaluations of future scenarios; however, it can provide a verification of bio-economically modeled economic values and it also has the advantage of implicitly incorporating any interactions of production with such traits as reproduction, calving interval and offsetting management factors. Thus the objectives of this study were to examine whether the economic values used for dairy cattle selection in Canada are the same for Officially supervised herds and for non-supervised Owner-Sampler herds (O/S), and whether the same economic values are appropriate for Holstein and Ayrshire breeds.
Proceedings of the World Congress on Genetics Applied to Livestock Production, Volume 2002. Session 1, , 1.2, 2002
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