Min Byeng R, Tomita Grant, Hart Steve P
E. Kika de la Garza Institute for Goat Research, Langston University, Langston, OK 73050, USA.
J Dairy Res. 2007 May;74(2):204-10. doi: 10.1017/S0022029906002378. Epub 2007 Jan 17.
We investigated effects of subclinical intramammary infection (IMI) on milk somatic cell count (SCC) and milk composition in udder halves of dairy goats. A total of 35 mixed-age Alpine does (70 udder halves; approximately 55 kg body weight) were rotationally grazed on a mixture of vegetative forages (wheat/berseem clover, sudan grass and cowpeas). Milk samples for bacterial analysis and SCC were collected monthly from both halves from April to September, 2001. Across stages of lactation, 19-31% of udder halves became infected. The prevalence of IMI exhibited quadratic patterns through multi-peaked responses within each stage of lactation. Higher rates of IMI were observed during the early stage of lactation (19% in May) and in the late stage of lactation (31% in September). Coagulase negative Staphylococcus (CNS, 43.7%), Staph. aureus (35.4%), and Pseudomonas aeruginosa (12.4%) were the most prevalent pathogens. Within single-strain IMI, log SCC (6.24) was lower (P<0.01) for CNS than those derived from IMI by Staph. aureus (6.49), Ps. aeruginosa (6.53) or Serratia spp. (6.90). Infected udder halves had a higher average SCC (4761 v. 2259 x 10(3) cells/ml; P<0.01) than uninfected halves, but uninfected halves often had similar levels of SCC to infected halves. Daily average milk production was not significantly different between infected and non-infected goats and the relationship between IMI and SCC was not always correlated. Effective mastitis screening requires bacteriological culture since SCC was not highly correlated.
我们研究了亚临床型乳房内感染（IMI）对奶山羊乳房两半部分的乳体细胞计数（SCC）和乳汁成分的影响。总共35只不同年龄的阿尔卑斯山羊（70个乳房半侧；体重约55千克）在由营养性草料（小麦/埃及三叶草、苏丹草和豇豆）组成的混合草料上进行轮牧。2001年4月至9月每月从两侧乳房采集用于细菌分析和SCC检测的乳汁样本。在整个泌乳阶段，19% - 31%的乳房半侧受到感染。IMI的患病率在泌乳各阶段呈现出多峰反应的二次曲线模式。在泌乳早期（5月为19%）和泌乳后期（9月为31%）观察到较高的IMI发生率。凝固酶阴性葡萄球菌（CNS，43.7%）、金黄色葡萄球菌（35.4%）和铜绿假单胞菌（12.4%）是最常见的病原体。在单一菌株引起的IMI中，CNS感染的乳房半侧的对数SCC（6.24）低于金黄色葡萄球菌（6.49）、铜绿假单胞菌（6.53）或沙雷氏菌属（6.90）引起的IMI（P<0.01）。受感染的乳房半侧的平均SCC（4761对2259×10³个细胞/毫升；P<0.01）高于未感染的半侧，但未感染的半侧的SCC水平常常与受感染的半侧相似。感染和未感染山羊的日均产奶量无显著差异，并且IMI与SCC之间的关系并不总是相关的。由于SCC相关性不高，有效的乳腺炎筛查需要进行细菌培养。
