Herd performance data in all of these four key areas will give a good assessment of management level and economic adaptability to the environment. These measures are economically the most important traits that producers should keep records on. Poor performance in any one of these is a clear signal to cull. The reproductive rate of a cow-calf operation is definitely affected by management. All performance record systems for commercial herds should be designed and used to evaluate the four keys to total herd performance.
Fertility is a trait generally considered to be of low heritability.
Therefore, the environment in which cattle must live and produce is an important factor in determining the reproduction level. Performance records established under a given environment and management system should be used to select or cull cattle within that environment and management system. Records should be used for more than just deciding whether a cow is culled or not. They should indicate how many cows are calving in the first 21 days of the calving season and the number calving in each subsequent 21-day period. If a computer program is used to summarize the cow data, it should include a computation of days from last calf.