Simulated Efficiency of Beef Production for a Midwestern Cow-Calf-Feedlot Management System. II. Mature Body Size

Abstract

A deterministic computer simulation model was used to study the effects of mature body size on the biological and economic efficiency of beef production for a Midwestern cow-calf-feedlot management system. If feed quality was not limiting, if slaughter cattle were fed at an intake level of twice maintenance and if the degree of maturity at weaning and at slaughter was the same for each size class, there was no indication from the simulation that mature body size affected the rate of conversion of total digestible nutrients (TDN) to weaning weight or empty body weight (EBW). However, if feed quality varied with season and class of cattle and if voluntary intake was allowed to vary in accord with the model assumptions, some advantages accrued to large types, although this result must be considered tentative and environment-dependent. If the price ratio of feedlot to cow herd TDN was 3.0, feed costs per 100 kg of EBW increased slightly as mature body size increased, whereas nonfeed costs per 100 kg of EBW declined. Total costs per 100 kg of EBW were generally less for large types, but this result was dependent upon the price ratio of feedlot to cow herd TDN. A wide range of size classes was potentially optimal, depending upon the prevailing economic conditions.