A three year herd health and management program on thirty Dutch dairy farms

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Abstract
Fertility control was part of a herd health and management program on thirty dairy farms in the province of Overijssel. A comparable control group of thirty‐one farms was available. After two years of application of the program the improvement in income feedcosts margin per cow on the program farms exceeded that on control farms by Dfl. 176. Within the large variation in income between the farms it was not possible to accurately distinguish the effects of the different aspects of the program, despite the use of detailed techniques such as Factor Analysis: thus another approach to determine the income effect of fertility control was necessary. The total loss per farm due to sub‐optimal fertility was determined, using calving interval data, forced replacement data and norm‐loss rates. From computation of this loss on program and control farms, the income effect of fertility control was deduced. Excluding the cost of the program, a significant (P <0.001) positive effect of fertility control on the total calculated loss due to sub‐optimal fertility was determined (average Dfl. 25.50 per cow, or about Dfl. 1,700 per farm, after two years of program application). This income effect differed considerably between farms with an initial good or poor situation regarding fertility. The program contributed more to the improvement of insufficient or moderate fertility than to the prevention of a deterioration in herds with excellent fertility, although on the latter farms the total program had a considerable positive effect.