Estimation of the economic value of fertility in the dairy cow

Abstract

The economic value of fertility in the dairy cow was analysed using a model. The expected future cash flow of a cow, given the average conception rate of the herd, was determined and maximized by dynamic programming which gives an optimum replacement policy. The marginal cost of a decrease in fertility was then estimated by the difference between the expected cash flow of a heifer at calving, divided by the difference in respective average conception rates. The estimate is a minimum because it excludes the cost of a suboptimal policy. It takes into account all the consequences of a change in fertility, i.e. culling rate, current and subsequent lactations and immediate costs. The estimate depends only on two kinds of parameters. It decreases when the average fertility rate increases or when the conditions of culling and replacement are more favourable, i.e. when the culling value is high and the replacement cost low. In present French conditions, using these parameters, the marginal value of 1 % change in conception rate is estimated between 10 and 20 FF per cow per year.