英文文献：How Do Alternative Milking Systems Differ Economically?
英文文献作者：Wetzel, Howard,Willet, Gayle,Stanton, Bud
英文文献摘要：
The milking operation is the most labor intensive activity in milk production. Labor costs, expressed as a percent of total milking system costs, may run as high as 82 percent for smaller, less mechanized systems [3]. Due to the high labor requirement for milking, dairymen have typically viewed, with considerable interest, the capital-labor tradeoffs associated with different parlors and with varying levels of mechanization on particular parlors. That interest has intensified in recent years due to rising labor costs, greater difficulty in finding and retaining competent milkers, larger herds, and new mechanization alternatives.