Bioeconomic evaluation of pasture sheep finishing using castor bean cake

Abstract This study evaluates the economic viability of sheep finishing systems on irrigated Tamani grass pasture under continuous stocking, using castor bean cake. Four production systems were simulated: sheep supplemented with soybean meal on pasture fertilized with urea (SMUR), sheep supplemented with detoxified castor bean cake on pasture fertilized with urea (CCdUR), sheep supplemented with soybean meal on pasture fertilized with in natura castor bean cake (SMCC) and sheep supplemented with detoxified castor bean cake on pasture fertilized with in natura castor bean cake (CCdCC). A minimum unit of 3 hectares and an average slaughter weight of 28 kg were considered. A minimum selling price, at which the least profitable system would become profitable, was stablished: US$ 2.38 and US$ 4.45/kg per kilogram of body weight and carcass weight equivalent, adopting a minimum rate of return of 3.5% per year, based on the Selic rate. The costs for organic fertilization were 46.01% higher than in systems using chemical fertilization. The selling of live animals was not attractive in any of the systems evaluated, and the opposite was observed for the selling of carcasses and non-carcass components. System SMUR proved to be more profitable, with a gain of US$ 0.53 per kg carcass.

摘要：本研究针对持续放牧模式下的灌溉塔马尼草（Tamani grass）牧场，评估了添加蓖麻饼（castor bean cake）的绵羊育肥系统的经济可行性。共模拟了4种生产系统：牧场施用尿素、补饲豆粕的绵羊组（SMUR）；牧场施用尿素、补饲脱毒蓖麻饼的绵羊组（CCdUR）；牧场施用天然蓖麻饼（in natura castor bean cake）、补饲豆粕的绵羊组（SMCC）；以及牧场施用天然蓖麻饼、补饲脱毒蓖麻饼的绵羊组（CCdCC）。本研究设定最小牧场单元为3公顷，平均屠宰体重为28千克。基于塞尔希克（Selic）利率设定年最低收益率3.5%，据此确定了使最低盈利系统实现盈利的最低售价：按活体体重和胴体重量当量计算，分别为每千克2.38美元和4.45美元。有机肥施用成本较化学肥料施用系统高出46.01%。所有评估系统中，活体动物售卖均不具备经济吸引力，而胴体及非胴体组分售卖则呈现截然相反的结果。其中SMUR系统盈利性最优，每千克胴体可获得0.53美元的收益。