Profitability of Dairy Cow Herd Life

Abstract

A dynamic model of a dairy herd was utilized to determine profitability of extending cow herd life. The model incorporated estimates of relationships between cow age, milk production, labor requirements, health costs, reproductive diseases, mastitis, and fertility. The basal situation simulated was a herd of ap- proximately 80 cows producing their own replacements selected by pedigree index, culling cows on cost per unit of produc- tion, and breeding cows by artificial insemination with a time trend for sire genetic merit. Increasing cow herd life was simulated by lowering the culling criteria of cow profitability. Extending herd life resulted in more days open, lower annual milk yield per cow, decreased replacement cost and cull cow income, and increased cow health cost. Criterion of herd profitability was discounted income of cow or annual net income over 25 yr with future returns discounted 5% per year. Extending average herd life from 2.8 to 3.3 lactations increased average annual income by $29.92 per cow and increased discounted income by $314.52 (1977 to 1978 dollars). The profitability of a limited increase of average herd life was insensitive to increased feed price, poor management, decreased salvage value, trend of improving management, but high salvage value and low feed price significantly decreased profitability of extended herd life.