Reproductive Traits and Their Heritabilities in Beef Cattle

Fertility is a complex trait in beef production systems and genetic evaluation procedures, which is partly due to the numerous measures used to assess reproduction. Beyond beef cattle, fertility measures vary according to animal species, and even within beef cattle, they vary by breed, location, sex, and class. Fertility is of significant economic importance to beef cattle producers, and therefore should be included in their breeding objective. However, traits considered indicative of fertility are in general of low heritability, are expressed late in the life of an animal, or both. Complicating genetic analyses is the binary nature of many of these traits because of truncation of data from short-controlled breeding seasons (typically 60 to 90 d long). Additionally, implementation of genetic prediction of reproductive traits in beef cattle has previously been hampered by a lack of total-herd data reporting systems. This review evaluates historic and current measures of assessing fertility and the heritabilities of these traits in beef cattle. Successful implementation of fertility traits into genetic improvement programs is dependent on whole-herd reporting and improved analysis techniques.