LIFE-CYCLE EVALUATION OF 5 BIOLOGICAL TYPES OF BEEF-CATTLE IN A COW-CALF RANGE PRODUCTION SYSTEM .2. BIOLOGICAL AND ECONOMIC-PERFORMANCE

Results from a 10-yr study of five dam breed groups in a range beef production system were used as inputs to a simulation model to evaluate life cycle biological and economic performance. Dam breed groups were straightbred Herefords (HH), Angus-Hereford and Simmental-Hereford F-1 crosses (AH and 1S1H), 75% Hereford-25% Simmental (1S3H), and 25% Hereford-75% Simmental (3S1H). Biological measures were number of lifetime matings, calves weaned and kilograms of calf weight sold per cow exposed, and metabolizable energy (ME) consumed per kilogram of calf weight sold and per kilogram of total weight sold. Simulated economic measures were break-even steer prices, total production costs, net profit per cow exposed, and net profit for a ranch of fixed size. The HH and 3S1H dams consumed the least ME per kilogram of total weight sold yet had the highest steer break-even prices and lowest profits. The Fl dams yielded consistently higher profits than other dam breed groups. Breed group rankings were not sensitive to prices paid for hay or calf prices relative to cow prices. Regression techniques were used to estimate maternal heterosis and maternal breed substitution effects from the simulated data. Maternal heterosis effects were large and highly significant for all measures of system performance and were desirable for all traits except ME/kilogram of total weight sold. Maternal heterosis for net profit was nearly $70-cow(-1) yr(-1) and $20,400/yr for a ranch of fixed size (2,700 AUM range forage). Maternal breed substitution effects were generally much smaller than heterosis effects. Longevity was greater for Hereford dams and annual costs/cow exposed were higher for Simmental dams, but substitution of Simmental dams for Hereford dams did not significantly affect break-even steer prices or profit.