The University of Arizona

Stocking rate risk for pasture-fed steers under weather uncertainty.

L.D. Parsch, M.P. Popp, O.J. Loewer


A biophysical model, GRAZE, is used to simulate beef forage performance for stocker steers pastured on common bermudagrass. Eight alternative stocking rates, ranging from low to high grazing intensity, are simulated over 14 simulated over 14 "states of nature" using historical weather data. The impact of weather variability on animal weight gain and economic performance is assessed and empirical cumulative distributions of net returns are developed. The risk efficient stocking rate strategies are identified for alternative decision-maker risk using generalized stochastic dominance. Under improved pasture conditions in Arkansas, results show that (a) expected weight gain per head is largely independent of grazing intensity until a critical stocking rate (6 hd/ha) is attained; (b) the highest expected net return per hectare is achieved under a lower stocking rate rate (10 hd/ha) than one which results in highest expected weight gain per hectare (12 hd/ha); and, (c) an increase in the stocking rate is accompanied by greater production (weather) risk which is reflected in increased variance of weight gain and net returns as well as a higher frequency and magnitude of economic losses.


biophysical simulation model;Arkansas;uncertainty;Cynodon dactylon;risk;simulation models;costs and returns;grassland improvement;market prices;production costs;liveweight gain;rain;stocking rate;steers;grazing intensity;forage

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