奶牛在哺乳期感染的与宿主相关的乳房炎，这些奶牛是在犊牛期通过饮用新鲜牛奶而共同饲养的。
Host adapted intramammary infections in pregnant heifers which were co-housed and reared on fresh milk as calves.
机构信息
Department of Production Animal Studies, Section Udder Health, Faculty of Veterinary Science, University of Pretoria, Private Bag X04, Onderstepoort 0110, South Africa.
出版信息
BMC Vet Res. 2013 Mar 15;9:49. doi: 10.1186/1746-6148-9-49.
BACKGROUND
Heifers can calve down with intramammary infections (IMI) and udder damage. This will have a negative impact on their longevity, future milk yield and financial return. Co-housed pre-weaned calves that are fed fresh milk have the opportunity to suckle each other's teats and may infect udders of fellow heifer calves with pathogens present in milk. The prevalence of IMI in pregnant heifers in South Africa (SA) which were co-housed and reared on fresh milk as calves, is not known. Quarter secretion samples from both pregnant heifers (n = 2065) and dry cows (n = 5365) were collected for microbiological analysis from eight SA dairy herds. All heifers tested in this study were co-housed pre-weaning and were fed fresh milk as calves.
RESULTS
The prevalence of coagulase negative staphylococci, Staphylococcus aureus, Streptococcus agalactiae, environmental streptococci, coliforms and samples with no bacterial growth in heifers was 26%, 0.9%, 0.08%, 1.4%, 0.4% and 66%, respectively. The overall prevalence ratio between heifers and cows for Staphylococcus aureus IMI was 0.76 (95% CI: 0.59, 0.98). Four of the individual herds had prevalence ratios of less than one (p < 0.05), one herd had a prevalence ratio of 3.15 (95% CI: 1.52, 6.32), and the remaining 3 herds had a prevalence ratio not significantly different from 1.0. Marginally significant differences were found between Staphylococcus aureus IMI in pregnant heifers compared to cows in their second and later lactations (p = 0.06, p = 0.05, respectively) but no significant differences between heifers and cows in their first lactation.
CONCLUSIONS
The presence of Streptococcus agalactiae IMI in heifers came as a surprise, especially as herd infection rates were low. The high prevalence ratio of Staphylococcus aureus between heifers and cows in one herd warrants further investigation due to the potential danger of udder damage in a young cow at the start of her productive life. The IMI in heifers with host adapted pathogens can also act as a source of new IMI for lactating dairy cows.
背景
奶牛犊牛在哺乳期可能会感染乳腺炎（IMI）和乳房损伤。这将对其寿命、未来产奶量和经济回报产生负面影响。共同饲养的未断奶小牛有机会互相吮吸乳头，并且可能会将牛奶中存在的病原体感染给其他奶牛犊牛的乳房。南非（SA）共同饲养和用新鲜牛奶饲养的怀孕奶牛中 IMI 的流行情况尚不清楚。从八个 SA 奶牛场采集了 2065 头怀孕奶牛和 5365 头干奶牛的四分体分泌物样本进行微生物分析。本研究中测试的所有奶牛犊牛均在哺乳期共同饲养，并在哺乳期用新鲜牛奶喂养。
结果
凝固酶阴性葡萄球菌、金黄色葡萄球菌、无乳链球菌、环境链球菌、大肠菌群和无细菌生长的样本在奶牛中的流行率分别为 26%、0.9%、0.08%、1.4%、0.4%和 66%。奶牛和奶牛金黄色葡萄球菌 IMI 的总体流行率比为 0.76（95%CI：0.59，0.98）。四个个体牛群的流行率比小于 1（p<0.05），一个牛群的流行率比为 3.15（95%CI：1.52，6.32），其余 3 个牛群的流行率比与 1.0 无显著差异。在怀孕奶牛与处于第二次及以后泌乳期的奶牛的金黄色葡萄球菌 IMI 之间发现了略有显著的差异（p=0.06，p=0.05），但在处于第一次泌乳期的奶牛与奶牛之间未发现显著差异。
结论
奶牛无乳链球菌 IMI 的存在令人惊讶，尤其是因为牛群感染率较低。一个牛群中奶牛与奶牛之间金黄色葡萄球菌的高流行率比值得进一步调查，因为这可能会对年轻奶牛在其生产生命开始时的乳房损伤造成潜在危险。具有宿主适应性病原体的奶牛的 IMI 也可能成为泌乳奶牛新 IMI 的来源。
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