T.R. Rounsaville

Modelling reproduction in a herd of dairy cattle.

Abstract A dynamic stochastic model to simulate the reproductive process in a herd of dairy cattle has been constructed. The next event scheduling approach was utilized with four events being specified: perturition, ovulation, embryonic loss and replacement. The control variables included in the model are first breeding policy ( 1BDG ), reproductive culling policy ( RCLG ), heat detection program ( HDPM ), breeding program ( BDPM ) and service sires selection program ( SSPM ). In addition, the model uses numerous endogenous variables such as parturition type (PRTY), oestrus behaviour (EBHV), cows fertility (CFTY), embryonic mortality (EBLS), non-reproductive culling rate (NRCL) and others. The model was evaluated against independent experimental results. The simulated result closely approximates the average reproductive performance and variability of reproductive performance in a dairy herd.