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The mortality of calves in the Iowa State College dairy herd^*

Iowa State College

Abstract

The constructive breeder of dairy cattle has to contend constantly with the problem of maintaining his herd in a profitable and productive state because of losses of breeding stock from death, disease, the culling of poor producers, and the culling of non-breeders.

Investigators vary in their statement of replacement requirements. McDowell (9) tabulated 10,000 yearly records from dairy herd improvement associations and found that on the average, cows remained in the herd 4.7 years after reaching productive age. Larson (5) found the average productive period to be 4.8 years upon analyzing the histories of 13,856 cows in the dairy herd improvement associations in New York. Thompson (14) from the records of 174 dairy farms in New York places the average productive life of dairy cows at 3.6 years. Munger (12) estimated this same average for 58 herds in Cerro Gordo County, Iowa, at 4.5 years. Lush and Lacy (7) gave 3.5 years as the average time a cow remains in the herd after her first freshening, this making an annual replacement figure of 28 percent.

^* Journal Paper No. J387 of the Iowa Agricultural Experiment Station. Ames, Iowa. Project 31.