美国是世界上牧草及饲料作物最大的生产国之一,每年生产1.27亿吨青干草(其中紫花苜蓿约占60％),价值50亿美元以上。此外,美国每年还生产1.2亿吨青贮饲料。众所周知,美国农村劳动力一直在急剧减少,目前农业劳动力只占总劳动力的5％还不到,近年仍有继续下降趋势。要以极其有限的劳力生产大量农畜产品,就必须不断提高农牧业生产过程机械化程度,努力寻求效率 The United States is one of the largest producers of pasture and feed crops in the world, producing 127 million tonnes of hay each year (about 60% of which is alfalfa) worth more than $ 5 billion. In addition, the United States also produces 120 million tons of silage per year. As we all know, the rural labor force in the United States has been drastically reduced. At present, the agricultural labor force accounts for only 5% of the total workforce and has continued to decline in recent years. To produce a great deal of agricultural and livestock products with extremely limited labor, we must continuously improve the mechanization of the farming and animal husbandry production processes and strive to seek efficiency