Bio-economic evaluation and optimization of livestock intensification options in the Central Highlands of Vietnam

Beef cattle have high market demand in Vietnam and the Dak Lak local government encourages the development of beef value chains. Household surveys were carried out in Cu Jut and Ea Kar districts and farming systems and production specialization were found to differ in each district. Ea Kar farmers were more specialized in livestock production while Cu Jut farmers were more focused on cash crop production. The FarmDESIGN bio-economic model allowed us to study two representative farms, one from Ea Kar and one from Cu Jut district. The Ea Kar farm had a more integrated livestock production system, providing manure to the fields that produced feed for the livestock. Both farms had high farm-level nitrogen balances due to high feed and fertilizer imports. The soil organic matter (SOM) balance in Cu Jut was negative (-48 kg/ha) because of its manure management strategy. On both farms, the residues were removed from the fields, providing no input to SOM and were fed to livestock (Ea Kar) or burnt (Cu Jut). Livestock intensification scenarios that were implemented for the Ea Kar case study farm showed two possible pathways – forage-based and grain-based cattle fattening. Both strategies could lead to higher operating profits (+35% for forage-based cattle fattening and +59% for grain-based cattle fattening) and lower labor demands if they were skillfully implemented for the latter scenario. However, grain-based fattening negatively affected SOM balance, in contrast to forage-based fattening. The optimization of the current Ea Kar farm with FarmDESIGN indicated that there are options to change the farm setup in order to increase profitability and reduce family labor demands. However there are some trade-offs to consider. If reducing environmental impact is a priority, there are alternative farm configurations that will produce lower greenhouse gas emissions while increasing SOM and increasing overall farm profitability. These should be assessed along with the farmers’ interests and priorities. Quantitative farm modeling of complex mixed farming systems can assess potential impact and support decision-making, targeting, prioritization and program design for sustainable intensification of livestock systems.

越南肉牛市场需求旺盛，得乐省（Dak Lak）当地政府积极推动肉牛价值链发展。研究团队在居朱县（Cu Jut）与亚嘎县（Ea Kar）开展农户调查，发现两县的农业生产系统与生产专业化程度存在显著差异：亚嘎县农户更专注于畜牧生产，居朱县农户则以经济作物种植为核心。本研究借助FarmDESIGN生物经济模型（FarmDESIGN bio-economic model），对两县各1家代表性农场展开分析。亚嘎县农场拥有更为一体化的畜牧生产系统，养殖场产生的粪肥可返还农田，为饲料作物提供养分。由于饲料与肥料进口量较高，两家农场的农场级氮素平衡均处于较高水平。居朱县农场的土壤有机质（soil organic matter, SOM）平衡为负值（-48 kg/ha），这与其粪肥管理策略直接相关。两家农场均会移除田间作物残体：亚嘎县将残体用作畜禽饲料，居朱县则将残体焚烧，均未向土壤补充有机质输入。针对亚嘎县案例农场的畜牧集约化模拟情景显示，存在两种可行的肉牛育肥路径：以饲草为基础的育肥模式，以及以谷物为基础的育肥模式。若实施得当，两种策略均可提升经营利润（饲草型育肥可提升35%，谷物型育肥可提升59%），且谷物型育肥模式还可降低劳动力投入需求。但与之相对，谷物型育肥会对土壤有机质平衡产生负面影响，而饲草型育肥则无此弊端。通过FarmDESIGN生物经济模型对亚嘎县现有农场进行优化分析后发现，可通过调整农场配置实现利润提升与家庭劳动力需求降低的目标，但需权衡相关利弊。若将降低环境影响作为优先目标，则可选择替代农场配置方案：这类方案既能减少温室气体排放，又可提升土壤有机质含量与整体农场盈利能力。此类方案需结合农户的利益与优先考量进行综合评估。针对复杂混合农业系统开展量化农场建模，可有效评估系统潜在影响，为畜牧系统可持续集约化的目标设定、优先级排序与项目设计提供决策支持。