Department of Animal Science, University of Minnesota, St. Paul 55108.
Department of Animal Science, University of Minnesota, St. Paul 55108.
J Dairy Sci. 2017 Nov;100(11):9466-9475. doi: 10.3168/jds.2016-12179. Epub 2017 Sep 6.
Recent trends in dairy farm structure in the United States have included a decreasing number of farms, although farm size has increased, especially the share of milk production from very large herds (>2,500 cows). The objectives of this observational study were to describe common management practices; to characterize labor and operational structure; to measure some aspects of animal health, including lameness, hock lesions, mortality, and mastitis incidence; and to summarize cost of production on farms with more than 2,500 cows in 4 states in the Upper Midwest of the United States. The study included 15 dairy farms in Minnesota, Wisconsin, Iowa, and South Dakota. Farms were visited twice, once each year, and on-farm herd records were collected for those 2 yr. On-farm herd records were used to investigate mortality, culling, pregnancy rate, and clinical mastitis incidence. At least 1 high-producing pen of mature cows and 1 pen of fresh cows were scored for locomotion. Likewise, at least 1 pen of high-producing mature cows was scored for cleanliness and hock lesions. Median herd size was 3,975 cows (range = 2,606-13,266). Milk sold per employee was 1,120,745 kg and the number of cows per employee was 105. Eighty percent of the farms had Holstein cows, 13% had Jersey, and 7% had Jersey-Holstein crosses. All farms used artificial insemination as the sole form of breeding and 100% of the farms used hormonal synchronization or timed artificial insemination programs in their reproductive protocols; 21-d pregnancy rate was 21.7%. Median lameness prevalence was 18.3% and median severe lameness prevalence was 5.1%. Median hock lesion prevalence was 17.4% and median severe hock lesion prevalence was 1.9%; mortality rate was 7.4%. Clinical mastitis incidence was 62.5 cases per 100 cow-years. Feed costs accounted for approximately 53% of the total cost of producing milk, followed by labor at 11%, interest and depreciation expenses at 10%, and replacement costs at 9.5%. Herds in the top 50th percentile for profitability had a net income of $2.40 per hundredweight of milk sold compared with $0.95 per hundredweight for herds in the bottom 50th percentile. Although results of this study were helpful in understanding how large dairy systems operate in the Upper Midwest, more research is yet needed with a larger number of farms and wider variety of management practices to identify factors within these large farms that promote optimal animal health and profitability.
美国奶牛场结构的近期趋势包括农场数量减少，尽管农场规模有所增加，特别是来自超大群（>2500 头牛）的牛奶产量份额增加。本观察性研究的目的是描述常见的管理实践；描述劳动力和运营结构；测量一些动物健康方面的指标，包括跛行、跗关节病变、死亡率和乳腺炎发病率；并总结在美国中西部 4 个州的超过 2500 头奶牛的农场的生产成本。该研究包括明尼苏达州、威斯康星州、爱荷华州和南达科他州的 15 个奶牛场。每年访问两次农场，并收集了这两年的农场牛群记录。使用农场牛群记录调查死亡率、淘汰率、妊娠率和临床乳腺炎发病率。至少有 1 个高产成母牛舍和 1 个后备牛舍的牛群进行了运动评分。同样，至少有 1 个高产成母牛舍的牛群进行了清洁度和跗关节病变评分。中位数牛群规模为 3975 头奶牛（范围=2606-13266）。每名员工销售的牛奶量为 1120745 公斤，每名员工的奶牛数为 105 头。80%的农场饲养荷斯坦奶牛，13%饲养泽西奶牛，7%饲养泽西荷斯坦奶牛。所有农场都只使用人工授精作为唯一的繁殖方式，100%的农场在繁殖方案中使用激素同步或定时人工授精程序；21 天妊娠率为 21.7%。跛行的中位数患病率为 18.3%，严重跛行的中位数患病率为 5.1%。跗关节病变的中位数患病率为 17.4%，严重跗关节病变的中位数患病率为 1.9%；死亡率为 7.4%。乳腺炎发病率为每 100 头奶牛 62.5 例。饲料成本约占产奶总成本的 53%，其次是劳动力占 11%，利息和折旧费用占 10%，以及更换成本占 9.5%。盈利能力排名前 50%的牛群每售出 100 磅牛奶的净利润为 2.40 美元，而排名后 50%的牛群每售出 100 磅牛奶的净利润为 0.95 美元。尽管本研究结果有助于了解美国中西部大型奶牛系统的运作方式，但仍需要更多的研究，包括更多的农场和更广泛的管理实践，以确定这些大型农场中促进动物健康和盈利能力的最佳因素。
