Stochastic modelling of dairy herds based on real production data to support management decision

• Main Author: Menasra, Souad
• Published: University of Reading 2005
• Subjects: 338.1
• Online Access: http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.487471

A stochastic simulation model of a dairy farm was, developed to allow the investigation of the effects of varying manage~ent decisions in dairy herds. The primary purpose of this model is to quantify the economic effects of different calving patterns with respect to production and reproductive performance. The revenues and costs associated. with dairy cows with different calving patterns were calculated. The feed costs were calculated according to the consumption of forage (silage or grass) and concentrate, as estimated from energy requirements. Furthermore, the replacement price, calf revenue and the financial loss associated with involuntary culling were considered. The economic value of fertility was estimated using this model; the change in gross margin as a result of an increase in fertility in the herd was estimated by changing the servicing and conception rates in the simulated herd. These changes had consequences for the culling rate and replacement costs. The. change in gross margin resulting from a 10% absolute change in servicing and a 5% change in conception rate was estimated to be between £50 and £90 per cow per year. Through improvement of both conception and servicing rates, careful management of reproduction can greatly improve profitability in a dairy herd. The model was also used to examine the economic consequences of relaxing fertility culling in an all-year calving herd. Model validation was conducted using data from National Milk Records; the validation was based on a comparison between the model and two contrasting real herds. The real herds were chosen by looking at the key performance indices within the Herd Companion tool. The model was then parameterised to simulate each of the contrasting real herds in turn.