Standardized Calculation and Interpretation of Basic Cow Herd Performance Measures

Commercial cow-calf producers commonly use the term “percent calf crop,” but what does it mean? Does percent calf crop represent the number of calves born relative to the number of cows bred, or perhaps it is the number of calves born relative to the number of cows exposed to a bull? Some might calculate percent calf crop as the number of calves weaned compared to the number of calves born, or the number of cows bred, or the number of cows exposed. Each of these mathematical “interpretations” of percent calf crop could be justified as a reasonable definition of the term. In fact, when students or producers are asked to calculate percent calf crop from a set of hypothetical herd information, given only their perception of what the term implies, multiple answers are typically generated, all mathematically correct. This creates a management issue, because how can percent calf crop be improved if producers have multiple perceptions of what the term implies? In the early 1990s, this issue was recognized and a task force consisting of both producers and academics were given the charge of developing standardized definitions for a variety of basic cow herd performance measures, including percent calf crop. When standardized definitions and calculations are used, comparisons can be generated, and herd management strengths and weaknesses are more easily identified and managed.