Jagannatha S, Keown J F, Van Vleck L D
Department of Animal Science, University of Nebraska, Lincoln 68583, USA.
J Dairy Sci. 1998 Jun;81(6):1702-8. doi: 10.3168/jds.S0022-0302(98)75737-6.
Lifetime records of 122,679 cows from 7557 herds, obtained from Mid States Dairy Records Processing Center (Ames, IA), were used to determine net income and net income for the planning horizon. With a planning horizon of five lactations for each cow, the estimated profit from the replacements was credited to each cow not surviving until fifth calving. Net income was defined as lifetime income minus costs. Net income for the planning horizon was defined as net income plus profit from replacements within the planning horizon. Income was from the sale of milk, calves, and culled cows. Costs were included for heifer rearing, feed, labor, and breeding. Longer herd life yielded greater profit for net income and net income for the planning horizon. The rate of increase in profit for longer herd life was reduced for net income for the planning horizon, which accounts for profit from cows replacing a culled cow compared with profit from net income. The relative economic value (phenotypic standard deviation basis) of production to herd life was 0.18:1 for net income and 0.46:1 for net income for the planning horizon. The relative value for herd life was overestimated by about 2.5 times when profit from replacements was not considered. Values for production relative to herd life increased for high milk prices and low feed prices. Lower prices for culled cows in combination with high prices for milk and feed increased the relative economic value of production.
从美国爱荷华州埃姆斯市的中部各州奶牛记录处理中心获取了来自7557个牛群的122679头奶牛的终生记录，用于确定净收入和规划期内的净收益。以每头奶牛五个泌乳期为规划期，将后备牛的估计利润计入未存活至第五次产犊的每头奶牛。净收入定义为终生收入减去成本。规划期内的净收益定义为净收入加上规划期内后备牛的利润。收入来自牛奶、犊牛和淘汰奶牛的销售。成本包括后备母牛饲养、饲料、劳动力和繁殖方面的费用。更长的牛群寿命为净收入和规划期内的净收益带来了更高的利润。规划期内净收益中，更长牛群寿命的利润增长率有所降低（与净收入的利润相比，这一规划期内的净收益包括了替代淘汰奶牛的母牛所产生的利润）。净收入中生产相对于牛群寿命的相对经济价值（基于表型标准差）为0.18:1；规划期内净收益中这一比例为0.46:1。当不考虑后备牛的利润时，牛群寿命的相对价值被高估了约2.5倍。牛奶价格高和饲料价格低时，生产相对于牛群寿命的价值增加。淘汰奶牛价格较低且牛奶和饲料价格较高时，生产的相对经济价值增加。
