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 本研究针对采用蓖麻饼粕饲喂、在灌溉条件下的塔玛尼（Tamani）草牧场开展连续放牧的肉羊育肥系统，评估其经济可行性。本研究共模拟了四类生产系统：以尿素施肥的牧场饲喂豆粕的肉羊系统（SMUR）、以尿素施肥的牧场饲喂脱毒蓖麻饼粕的肉羊系统（CCdUR）、以天然蓖麻饼粕作为肥料的牧场饲喂豆粕的肉羊系统（SMCC），以及以天然蓖麻饼粕作为肥料的牧场饲喂脱毒蓖麻饼粕的肉羊系统（CCdCC）。本研究设定最小牧场经营单元为3公顷，肉羊平均屠宰体重为28千克。基于塞利克（Selic）基准利率，采用每年3.5%的最低收益率标准，确定了令盈利性最差的系统实现盈利所需的最低售价：按活体体重和胴体重量计价时，该售价分别为每千克2.38美元和4.45美元。有机肥施肥成本较化学施肥系统高出46.01%。所有评估系统中，活体牲畜销售均不具备经济吸引力，而胴体及非胴体组分的销售则呈现完全相反的经济表现。其中SMUR系统的盈利性最优，每千克胴体可实现0.53美元的收益。