Barkema H W, Schukken Y H, Lam T J, Beiboer M L, Wilmink H, Benedictus G, Brand A
Animal Health Service, Drachten, The Netherlands.
J Dairy Sci. 1998 Feb;81(2):411-9. doi: 10.3168/jds.S0022-0302(98)75591-2.
Incidence of clinical mastitis was studied in 274 herds grouped in three categories by bulk milk somatic cell count (SCC). Mean incidence rate of clinical mastitis was 0.278, 0.257, and 0.252 cases per 365 cow-days at risk in herds with low (< or = 150,000), medium (150,000 to 250,000), and high (250,000 to 400,000 cells/ml) bulk milk SCC, respectively. The incidence rate of clinical mastitis was not different among the three categories. Variance in the incidence of clinical mastitis among herds increased as bulk milk SCC decreased. Clinical mastitis caused by Gram-negative pathogens, such as Escherichia coli, Klebsiella spp., or Pseudomonas spp., occurred more often in herds with a low bulk milk SCC. Clinical mastitis caused by Staphylococcus aureus, Streptococcus dysgalactiae, and Streptococcus agalactiae occurred more often in herds with a high bulk milk SCC. Systemic signs of illness caused by clinical mastitis occurred more often in herds with a low bulk milk SCC. Both overall culling rate and culling rate for clinical mastitis were not different among groups catergorized by bulk milk SCC. In herds with a high bulk milk SCC, however, more cows that produced milk with a high SCC were culled. In herds with a low bulk milk SCC, more cows were culled for teat lesions, milkability, udder shape, fertility, and character than were cows in herds with a high bulk milk SCC. In herds with a low bulk milk SCC, cows were also culled more for export and production reasons.
根据原料奶体细胞计数（SCC），将274个牛群分为三类，研究临床型乳房炎的发病率。原料奶SCC低（≤150,000）、中（150,000至250,000）、高（250,000至400,000个细胞/毫升）的牛群中，临床型乳房炎的平均发病率分别为每365个奶牛日0.278、0.257和0.252例。三类牛群中临床型乳房炎的发病率没有差异。随着原料奶SCC降低，牛群中临床型乳房炎发病率的方差增加。由革兰氏阴性病原体（如大肠杆菌、克雷伯氏菌属或假单胞菌属）引起的临床型乳房炎在原料奶SCC低的牛群中更常见。由金黄色葡萄球菌、无乳链球菌和停乳链球菌引起的临床型乳房炎在原料奶SCC高的牛群中更常见。临床型乳房炎引起的全身疾病症状在原料奶SCC低的牛群中更常见。按原料奶SCC分类的各组中，总体淘汰率和临床型乳房炎淘汰率没有差异。然而，在原料奶SCC高的牛群中，更多体细胞数高的奶牛被淘汰。在原料奶SCC低的牛群中，因乳头病变、挤奶能力、乳房形状、繁殖力和性格等原因被淘汰的奶牛比原料奶SCC高的牛群中的奶牛更多。在原料奶SCC低的牛群中，奶牛也因出口和生产原因而被更多地淘汰。
