Derived demand relationships among four weight categories of feeder cattle entering Texas feedlots and their feed consumed are examined using a generalized McFadden dual cost function. Results demonstrate systematic differences in demand relationships among different weight categories. Positive cross-price elasticities among the three heaviest weight categories are consistent with input substitution among weight categories and consistent with objective functions associated with optimal placement weight. Anomalies in the form of negative cross-price elasticities between weight categories provide evidence for an alternative objective function associated with longer term feeding of light-weight feeder cattle. Results also demonstrate seasonality differences across weight categories.