Heifer Breeding Maturity and Its Effects on Profitability

The question of determining the size at which to breed beef replacement heifers is not a new one. This research differs from most in the literature in three major ways. First, analysis of biological relationships is done on the basis of individual animals rather than experimental groups. Second, outcomes from biological analysis are used to simulate results that are analyzed. Finally, analyzed results are in terms of profitability rather than biological measures. The basis for identifying biological relationships used in the simulation are a series of integrated models (regression equations) derived by using the AIAKE loss criterion to optimally select those relationships expressed as equations from individual animal data. The final simulation uses the relationships indentified in the biological subsystems and translates them through the appropriate economic conditions (cost and revenue) to determine a cow profitability score or MPF. Results show optimal profitability depends on relationships between a number of factors rather than any one or two individual factors. Because results depend on relationships between factors, an index is presented as a tool for replacement heifer selection.