A Simulation Study on the Effects of Cow Size and Milk Production on Bioeconomic Efficiency of Range Beef Cattle

Abstract

Pang, H., Makarechian, M.H. and Basarab, J.A. 1999. A simulation study on the effects of cow size and milk production on bioeconomic efficiency of range beef cattle. J. Appl. Anim. Res., 16: 119–128. A dynamic simulation model, Alberta Beef Production Simulation System (ABPSS) was used to evaluate the effects of cow size (mature cow weights of 450, 550 and 650 kg), milk production (peak milk yields of 5.4, 8.2 and 10.9 kg d−1), calf market price (low, medium and high) and their interactions on bioeconomic efficiency of cow-calf production systems. The model is composed of four main submodels: Herd Inventory, Nutrient Requirements, Forage Production and Economics. Bioeconomic efficiency was defined as the difference between total cost and total return. The results of simulations indicated that dry matter intake (DMI) and total cost per cow increased with increasing cow size. At a. constant weaning age of 200 days, medium size cows had the maximum bioeconomic efficiency at the low price level, while large size cows had the highest bioeconomic efficiency at the high price level. The results indicate that there are significant interactions between cow size and market price for bioeconomic efficiency. At a constant weaning age (200 d), calf forage DMI decreased with higher milk production, but calf milk DMI, cow DMI and total cost per cow increased with higher milk production. The high milk producing cows had the highest bioeconomic efficiency because of heavier calves at weaning, regardless of price level and the cow size.