Dairy Cow Culling Decision. 2. Profitability and Genetic Trend in Herds with Culling on Production Versus Income

Abstract

A technique has been described for culling cows on a combination of screening the entire herd on short-term income and then culling the cow making the smallest contribution to herd income over probable remaining herd life. The objective of this study was to determine the long-term effects on herd profitability and herd genetic trend of culling on a combination of short-term and long-term cow income instead of culling on age adjusted production. In addition, the effect of timing of the culling decision either prebreeding (to save insemination costs) or postbreeding (when time of next freshening can be predicted) on herd income was evaluated. Culling on projected income increased herd income over 20 yr by 4.3 to 4.8% relative to culling on age adjusted production for complete lactation. Breeding only the highest producing cows and then culling infertile cows at the point of peak income in the lactation increased herd income over 20 yr by 4.3 and 5.7% relative to breeding all cows and then culling the lowest producing cow in the herd when a heifer freshened. Cow culling on income projections decreased the genetic trend to 65.3 to 86.2% of the gain observed with cow selection on age adjusted production. Due to the potential economic benefits from both choosing culls prebreeding and utilizing a profitability criterion for cow culling, income projection techniques that describe the reproductive performance of the open cow need to be developed.