Simulation of the economic feasibility of fodder shrub plantations as a supplement for goat production in the north-eastern plain of Mendoza, Argentina

Abstract

The economic feasibility of Atriplex nummularia Lindl. and spineless cactus ( Opuntia spp.) plantations for supplementing goats in the north-eastern plain of Mendoza (mean annual rainfall = 175 mm) during the fall–winter period was examined by a simulation model. It was run with 50–200 goats and annual rainfall probability ( p;10–90% probability of occurrence). Cactus production was estimated from a rain-use efficiency factor of 12·5 kg DM ha −1 year −1 mm −1 and the annual rainfall probabilities in the area. Saltbush production (1·88 t DM ha −1year −1) was assumed not to be affected by annual rainfall thanks to the presence of a, 5–10 m deep, moderately saline water table (3·5–5·0 dSm −1). A decrease in goat mortality and an additional number of kids per goat were considered as annual benefits derived from supplementing the goat diet. The establishment cost (US$ ha −1) ranged from 812 (50 goats; p 0·1 ) to 317 (200 goats; p 0·9) for cacti plantations and from 691 (50 goats) to 378 (200 goats) for saltbush plantations, amounts that not all stockmen could afford. The cost of metallic fence installation was the main item of establishment cost for both shrubs. The nutrient costs for shrub production were lower than those for alfalfa hay, the conventional feed used by stockmen. A decrease in doe mortality from 10% to 2% and an increase in annual kid crop ranges from 0·17 to 0·32 would economically justify shrub plantations for stockmen having more than 50 goats at annual rainfall probabilities from p 0·1 to p 0·8. Limitations of the modelling effort and the feasibility of using the model in other areas of the world were stated.