Optimal heifer management decisions and the influence of price and production variables

A dynamic programming model was developed to optimize the rearing strategy of individual heifers. The model optimized management decisions with respec t to growth rate, insemination and replacement by maximizing the present va lue of net returns per heifer place. Faced with the scarcity of exact infor mation on the fundamental elements of heifer rearing, sensitivity analyses were carried out to evaluate the technical and economic consequences of var ious price and production variables. Results for Dutch conditions showed th at it was most profitable to rear heifers at the highest achievable growth rates without fattening. Based on a critical prepubertal average daily gain (ADG) of 900 g/day and a maximum achievable postpubertal ADG of 700 g/day, optimum policy resulted in an average age of first calving of 21.2 months at a body weight of 541 kg. The sensitivity analyses demonstrated a conside rable impact of the critical prepubertal growth rate on both the optimal re aring policy and expected net returns. Technical and economical results wer e also very sensitive to seasonal influences on price and production variab les. Heifer calves born in winter were the most profitable calves to rear. (C) 1999 Elsevier Science B.V. All rights reserved.