Optimal replacement and insemination policies for Holstein cattle in the southeastern region of Brazil: the effect of selling animals for production.

Abstract

Dynamic programming was used to determine optimal replacement and insemination policies for Holstein-Friesian cattle in the southeastern region of Brazil. Optimal insemination and replacement decisions were determined for two disposal alternatives: selling all cows exclusively for slaughter (A) or selling the cows either for slaughter or to other farmers for production (B). Disposal alternative B reflects the common practice among dairy farmers to sell some of their cows to other farmers at a higher price than the carcass price. In the model, cows were described in terms of lactation number, stage of lactation, calving interval, and milk produced during present and previous lactation. For disposal alternative A, the optimal average herd life was 54.9 mo, corresponding to annual replacement and voluntary culling rates of 21.8 and 4.1%, respectively. For disposal alternative B, the optimal average herd life was 44.0 mo, which corresponded to annual replacement and voluntary culling rates of 27.3 and 10.0%, respectively. In this case, from the total of voluntarily culled cows, 70% were sold to other farmers for production. Sensitivity analyses showed that changes in the disposal value of cows and replacement heifer prices strongly influenced the optimal insemination and replacement policy.