Justification for grazing intensity experiments: economic analysis.

Abstract

Economic arguments in favor of grazing intensity trials are provided by economic analysis of grazing intensity results from Coastal, Callie and experimental hybrid S-16 bermudagrass (Cynodon dactylon L. Pers), and by emphasizing the biological and economic differences among cultivars. Cattle buying prices of $1.20, $1.30, and $1.40/kg and price margins (selling price minus buying price) from -$O.20 to $0.20 were considered on a return/ha and /animal basis, assuming land or capital to buy animals to be limiting, respectively. When price margin was -$O.20, the stocking rate at which profit/ha was maximized ranged from 4.19 to 5.85 animals/ha, while profit/animal was maximized between 4.77 and 6.89 animals/ha. Corresponding ranges in average weight of herbage present/ha which maximized profit/ha and /animal were 2.83 to 3.60 Mg and 2.34 to 3.72 Mg. For a price margin of $O.20, profit/ha and /animal were maximized at stocking rates of 7.36 to 9.86 and 4.14 to 5.93 animals/ha respectively, with corresponding levels of herbage present/ha in the ranges 0.33 to 1.79 Mg and 2.73 to 4.06 Mg. Relative differences in profit/ha and /animal among cultivars did not correspond to differences in gain/ha and /animal. Economic comparison of the cultivars considered in this study would have had little relevance if only one grazing intensity had been used in the field trial. Only grazing trials with several grazing intensities per treatment can allow for the determination of economic optimum grazing intensities in respect of a wide range in economic conditions.