Optimal cow replacement on New Zealand seasonal supply dairy farms

B.L. Harris

Livestock Improvement Division, New Zealand Dairy Board, Hamilton

Proceedings of the New Zealand Society of Animal Production. 1988, 48: 243-246

Dairy farmers made management decisions each season about which cow to replace. At present dairy farmers can use the production index. The production index is an historical measurement of a cow's milkfat production ranking, free from the influences of herd environment, age, stage of lactation and herd genetic level.

A dynamic programming method is outlined which incorporates genetic, reproductive and economic information. This method ranks cows on their annualised present value. A sensitivity analysis was undertaken and the effects of the changes in the different economic parameters are discussed. The optimal cow rankings produced by the dynamic programming method were shown to be robust to changes in milkfat, manufacturing beef and heifer replacement prices and interest rate.

Keywords: NZSAPAB; Replacement; optimal; dynamic programming; dairy cattle

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Last Updated 18-03-1997