Culling Cows on Predicted Future Profitability with a Variable Planning Horizon

Abstract

A technique was developed to evaluate economic consequences of the culling decision. The culling decision was based on comparisons of net present value of predicted income of the cow and her potential replacement for planning periods up to 10 calving intervals. For planning periods longer than 2 calving intervals, rate of culling increased because the decline in productivity of cows beyond sixth lactation was included in the planning period. Culling on net present value of predicted income resulted in a cow average herd life close to the average herd life expected to maximize herd income. Relatively few cows (<9% of 2 yr olds) were culled in culling on income projections compared to most commercial herds. Lengthening the planning horizon increased long-term income more than short-term income. Variation in length of planning period affected net present value of herd income less than mean annual herd income because long-term income was the most heavily discounted. The increase of income in extending the planning horizon beyond next lactation was sufficient to use probable remaining herd life as the planning period for cow culling.