Kahi A K, Kosgey I S, Cardoso V L, Van Arendonk J A
Institute of Animal Production in the Tropics and Subtropics, Hohenheim University, Stuttgart, Germany.
J Dairy Sci. 1998 Aug;81(8):2271-9. doi: 10.3168/jds.S0022-0302(98)75807-2.
The ranking of genotypes (i.e., breeds and breed crosses) for economic performance depends on the production circumstances of the herd and the criteria for economic evaluation. In this study, the effects of evaluation criteria and production circumstance are quantified using data from the literature on six genotypes. The economic evaluation criteria measured at herd level included lifetime profit and lifetime profit expressed per day of calving interval, per day of productive lifetime, per day of total herd life, per unit of milk, and per unit of feed energy. Four production circumstances were studied; these circumstances included constraints on the output of milk and on herd use of concentrates, roughages, and both concentrates and roughages. Profit was determined based on the sale of milk, calves, cull cows, and heifers and the expenses incurred for concentrates and roughages, animal deaths, milking time, interest, and other inputs. Results indicate that production circumstances and evaluation criteria largely influence the ranking of genotypes and, therefore, the outcome of economic comparisons. The genotype that ranks the best under a certain criteria and circumstance ranks differently when these situations are altered. In economic comparisons of genotypes aimed at offering recommendations for implementation in smallholder dairy production systems in the tropics, the choice of the evaluation criteria should be determined by the limitation or constraint that characterizes the area where the genotypes are to produce or are currently producing. For example, for situations in which feed availability is limiting, genotypes should be ranked on total profit per unit of feed energy.
基因型（即品种及其杂交品种）在经济性能方面的排名取决于牛群的生产环境以及经济评估标准。在本研究中，利用来自六种基因型的文献数据，对评估标准和生产环境的影响进行了量化。在牛群层面衡量的经济评估标准包括终身利润以及按产犊间隔天数、生产寿命天数、牛群总寿命天数、每单位牛奶和每单位饲料能量表示的终身利润。研究了四种生产环境；这些环境包括对牛奶产量以及牛群对精饲料、粗饲料以及精饲料和粗饲料两者使用的限制。利润是根据牛奶、犊牛、淘汰母牛和小母牛的销售情况以及精饲料和粗饲料、动物死亡、挤奶时间、利息和其他投入所产生的费用来确定的。结果表明，生产环境和评估标准在很大程度上影响基因型的排名，因此也影响经济比较的结果。在特定标准和环境下排名最佳的基因型，当这些情况发生变化时，排名也会不同。在旨在为热带地区小农户奶牛生产系统的实施提供建议的基因型经济比较中，评估标准的选择应取决于基因型将要生产或当前正在生产的地区所具有的限制条件。例如，在饲料供应有限的情况下，基因型应按每单位饲料能量的总利润进行排名。
