An economic comparison of four insemination and culling policies in dairy herds, by method of stochastic simulation

In a stochastic dairy herd simulation model the economics of four insemination and culling policies with a potential practical application were compared. Two policies were based on a single criterion with a fixed cut-off point for service and two varied the culling rule according to poductive capacity and stage of lactation of individual cows. At the lowest levels of heat detection (¸<50%) and conception rates (¸<40%) there is almost no prospect for any additional selection on poor productive and reproductive performances. The advantage of a shorter calving interval is outweighed then by increased herd turnover and replacement. In better performing herds the potential benefits of detailed management guides for decisions on insemination and culling, as developed in previous research by dynamic programming, ranged from Dfl.30 to Dfl.45 per cow per year compared with no specific selection on poor productive and reproductive performance. Compared with a simplified version of this strategy, to be provided to farmers without additional computerized support, these benefits were found to be no more than Dfl.10 per cow per year. Expectation about income improvement of providing detailed insemination and culling guides on a routine scale, as currently being explored in The Netherlands, therefore , should not run too high. More (model) research is desired to determine the potential profitability of extended applications of such guides, e.g. for decisions on veterinary treatment and milk quota managing.