Sessim Amir Gil, de Oliveira Tamara Esteves, López-González Fredy Andrey, de Freitas David Santos, Barcellos Júlio Otávio Jardim
Department of Animal Science, Faculty of Agronomy, Núcleo de Estudos em Sistemas de Produção de Bovinos de Corte e Cadeia Produtiva (NESPro), Federal University of Rio Grande do Sul (UFRGS), Porto Alegre, Brazil.
Plant Ecology Laboratory, University of Vale do Rio dos Sinos (UNISINOS), São Leopoldo, Brazil.
Front Vet Sci. 2020 Aug 5;7:476. doi: 10.3389/fvets.2020.00476. eCollection 2020.
The bioeconomic efficiency of cow-calf systems was compared by a deterministic dynamic simulation. The simulation model considered stable cow-calf systems differentiated by the maximum age for culling cows, lifetime, culled at 4-13 years old. The necessary supply of metabolizable energy for the herd was established as natural grasslands, cultivated pasture in the winter/spring, and pre-dried pasture produced by the system. The biological efficiency of the systems was considered the ratio between the production of total live weight and the metabolizable energy consumed over one production cycle. Economic efficiency was determined by the ratio between gross margin and production area and the ratio between gross margin and number of cows. Bioeconomic efficiency was determined by a simple linear regression between biological efficiency, economic efficiency per area, and economic efficiency per cow. The efficiency of the animal unit, considering biological efficiency and economic efficiency per area were better in the system that culled cows at 4 years old, while economic efficiency per cow was better in the system that culled cows at 13 years old. In determining the bioeconomic efficiency of the systems, the best results were found in the system that culled cows at 6 years old, which suggests that the best efficiency of a cow-calf herd is reached when the adult age and mature weight of the cow are reached, and there is no more energy used for growing. The results indicate that stable cow-calf herds express their best biological efficiency and economic efficiency per area when the cow culling age is lower. However, economic efficiency per cow depends on cows that remain in the herd as long as possible. The culling age of cow that balances these biological and economic indicators is reached around 5 and half years.
通过确定性动态模拟比较了母牛-犊牛系统的生物经济效率。模拟模型考虑了稳定的母牛-犊牛系统，这些系统因淘汰母牛的最大年龄不同而有所差异，淘汰年龄在4至13岁之间。牛群所需的代谢能供应设定为天然草地、冬春季节的人工牧场以及系统生产的预干牧场。系统的生物效率被视为一个生产周期内总活重产量与消耗的代谢能之间的比率。经济效率由毛利率与生产面积的比率以及毛利率与母牛数量的比率确定。生物经济效率由生物效率、单位面积经济效率和每头母牛经济效率之间的简单线性回归确定。考虑到生物效率和单位面积经济效率，4岁淘汰母牛的系统中动物单位效率更高，而13岁淘汰母牛的系统中每头母牛的经济效率更高。在确定系统的生物经济效率时，6岁淘汰母牛的系统取得了最佳结果，这表明当母牛达到成年年龄和成熟体重，且不再有能量用于生长时，母牛-犊牛群达到最佳效率。结果表明，当母牛淘汰年龄较低时，稳定的母牛-犊牛群表现出最佳的生物效率和单位面积经济效率。然而，每头母牛的经济效率取决于尽可能长时间留在牛群中的母牛。平衡这些生物和经济指标的母牛淘汰年龄约为5岁半。
