Bio-economic models for adaptive livestock management on semi-arid rangelands in Texas. Dube, Sikhalazo^*,1, Diaz-Solis, Heriberto³, Kothmann, Merwyn¹, Teague, Richard², Kreuter, Urs¹, Grant, William⁴, ¹ Department of Rangeland Ecology and Management, College Station, Texas, USA³ Departmento de Recorsos Naturales, Saltillo, Coahuila, Mexico² Texas Agricultural Experimental Station, Vernon, Texas, USA⁴ Department of Wildlife and Fisheries Sciences, College Station, Texas, USA

ABSTRACT- A deterministic compartmental model, Bio-Economic Model for Adaptive Livestock Management (BEMALM) was developed for cow-calf enterprise for Rolling Plains of Texas. The model simulates forage and animal production. Three stocking strategies conservative, flexible(40% utilization) and fixed heavy were evaluate for effects on forage and animal production, range condition, and net ranch income Evaluation data was obtained from publication and unpublished data from Texas A&M Experimental Station at Vernon for Throckmorton. The model sufficiently simulated forage and animal production; and the dynamics. Animals under conservative stocking were heavier (517 kg) than either those under flexible (500 kg) or heavy (483 kg) stocking. Replacement rates were lower under conservative stocking (17%) compared to flexible (29%) and heavy stocking (43%). Calf crops were all above the reported 95% expected for bred heifers Flexible stocking strategy ($54.00.ha-1) economically out performed either conservative ($33.71.ha-1) or heavy ($33.21.ha-1) stocking strategy. Variation in net income was high under flexible (17%) and heavy (17%) stocking strategy compared light stocking (8%), economic risk is high under flexible stocking. Range condition declined rapidly under heavy stocking, increase under conservative and remained constant under flexible. Use of conservative stocking has the potential of improving range condition over time while flexible stocking could maintain range in fair condition. Heavy stocking decreases rapidly range condition. BEMALM can inform decisions, and be used in assist producer training. The model is a tactical decision aid; it does not replace intimate knowledge of operations. It is concluded that there is potential for models in sustainable agriculture.

KEY WORDS: bio-economic model, adaptive, cow-calf, texas