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Summary of thesis

 

 

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

 

 Souad Menasra

 

 

A stochastic simulation model of a dairy farm was developed to allow investigation of the effects of varying management decision in dairy herd. The primary purpose of this model is to quantify the economic effect of different calving season with respect to production and reproductive performance. The revenues and costs of dairy cows with different calving season were calculated. The feed costs were calculated from consumption of forage (silage or grass) and concentrate, which were estimated from the energy requirements. Furthermore, the course of replacement price, calf revenue and the financial loss associated with, involuntary culling was considered.

 

The economic value of fertility was estimated by using the model, the gross margin of an increase in fertility in the herd was then estimated to the difference of respective average of service and conception rates in the herd. The estimated result was high taken into account the consequences of a change in fertility, i.e. on culling rate, and on costs. The gross margin of 10% absolute change in service and 5% in conception rates was estimated to be between £50 and £90 per cow per year. These values increased when the average fertility level increased. Improving both conception and service rates provides opportunities for management control of reproduction and 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. To quantify the economic effects of different culling policies with respect to reproductive failure. The expected gross margin of the cow as an annuity equivalent under various culling strategies an estimate of the value of longevity was obtained. Increased longevity by 11 parity added about £100 per cow per year in gross margin.

 

Model validation was conducted using data from NMR; the validation was based on comparison between the model and two contrasting real herds. The real herds were chosen by looking at KPIs within the Herd Companion tool. The comparison of actual and simulated data indicated that the model did simulate the response of input variables setting. The validation procedures have demonstrated that the model can produce realistic simulation of different herd’s fertility performance.

 

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