A LINEAR-PROGRAMMING FORMULATION OF THE MARKOVIAN DECISION-PROCESS APPROACH TO MODELING THE DAIRY REPLACEMENT-PROBLEM

In modelling the replacement decision in dairy herd management, the mo st common approach taken is to use dynamic programming to determine th e optimal policy by comparing the future expected profitability of an animal to that of it's potential replacement. It does not, however, ta ke into account the performance of the entire herd or that of all pote ntial replacements, which is particularly important if replacements or iginate from the same herd. This paper demonstrates how to overcome th is inadequacy by formulating the problem as a multi-component Markovia n decision process and then solving it as an associated linear program ming model. The proposed methodology is illustrated by using a simple, but realistic, example for determining the optimal replacement strate gy for a dairy herd over a 10-year planning horizon. The results show that replacements should be bred from heifer cows in order to increase the genetic turnover; however, no move animals than is necessary shou ld be culled to increase this turnover. It is also shown how to includ e considerations such as problems of milk quota management, and other similar resource allocation decisions into the model. Additional impro vements to the model could involve considering culling of animals suff ering from disease. (C) 1998 Elsevier Science Ltd. All rights reserved .