Genetic Improvement of Heifer Pregnancy and Performance in Beef Cattle

Current genetic improvement programs should place more emphasis on improving profitability than on one or a small group of traits, under the framework of economic relevance (Golden et al., 2000). When profit is defined generally as revenue minus cost, true economically relevant traits (ERT) have a direct impact on either income or expenses, whereas indicator traits provide a means to increase accuracy of evaluation through their genetic correlation with ERT but are not directly economic (Enns and Crews, 2008). It is important, therefore, to distinguish between ERT and their indicators in the design and implementation of genetic evaluation and improvement programs for beef cattle. Traits related to fertility and maternal productivity are certainly a key component of improving the profitability of beef production. In fact, fertility traits are typically ranked as having a greater impact on revenue in beef production than other groups of traits such as growth performance and carcass merit (Melton, 1995). Enns and Crews (2008) identified traits such as calving ease, heifer pregnancy, bull fertility, health status, stayability or productive longevity, milk production, and calf and cull cow sale weights as likely ERT for the large cow-calf sector of the North American beef industry.