G enetic relationships between calving date, calving interval, age at first calving and type traits in beef cattle

In this paper the genetic relationships between major reproductive traits in beef cattle (Calving Date, Calving Interval and Age at First Calving) and type traits have been estimated to evaluate the usefulness of type classification in predicting reproductive performance in beef cattle. We estimated favourable genetic correlations between Calving Interval and type traits ranging from 2 0.027 to 2 0.297. However, type traits and Calving Date appear to be genetically independent and the genetic relationships between Age at First Calving and type traits are, in general, non-favourable. Genetic correlations between type traits and Calving Date ranged from 0.0 to –0.125. Genetic correlations between Age at First Calving and Final Score, Body Depth and Tight Development were, respectively, 0.399, 0.445 and 0.447. Our results suggest that the possibility of using type classification to construct an index to improve reproductive performance is little. The more reliable possibility to build a possible selection index comprising type classification and reproductive performance would be based on Age at First Calving. Type classification at first calving could help to increase the information to select dams to stay on the farm in subsequent calvings on the basis of their expected performance.  2002 Elsevier Science B.V. All rights reserved.