Epidemiology of mastitis in pasture-grazed peripartum dairy heifers and its effects on productivity
Epidemiology of mastitis in pasture-grazed peripartum dairy heifers and its effects on productivity
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DOI：
10.3168/jds.2006-880
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发表时间：
2007-09-01
影响因子：
3.5
通讯作者：
McDougall, S.
中科院分区：
文献类型：
--
作者：
Compton, C. W. R.;Heuer, C.;McDougall, S.
对新西兰怀卡托地区30个春季产犊奶牛群的708头小母牛进行了野外观测研究。本研究的目的是描述围产期内乳房感染(IMI)和临床性乳腺炎(CM)的模式和影响。除在产犊后14天内确诊为CM的季度外，还从产犊计划开始前约3周和产犊后5天内从所有地区采集乳汁样本进行细菌学检测。18.5%的季度诊断为急性心肌梗死，其中以凝固酶阴性葡萄球菌为主(13.5%)。与产牛期前相比，产牛链球菌感染率在产犊当天增加了4倍，达到10.0%。所有病原体的流行率在产犊后迅速下降。临床乳房炎病例主要与链霉菌感染有关。Uberis(%)。小母牛的每日诊断风险高于奶牛(第1天分别为0.06vs.0.02/d)，但在哺乳第5天时差异不大(分别为0.005和0.002)。乳房内感染一种主要病原体会增加从牛群中取出的风险(感染和未感染的小母牛分别为15%和10%)，并在随后的牛群测试中增加体细胞计数200,000个细胞/毫升(15%对8%)，但CM和IMI都与产奶量或乳固形物产量下降无关。结果表明，牧草围产期小母牛感染的细菌种类和流行模式与其他生产系统中的不同。此外，乳房炎控制计划需要针对导致生牛犊前IMI的主要环境病原体，因为新的感染可能在哺乳开始之前发生，而现有的检测和控制措施通常是在产犊之后实施的。新的控制程序，减少由于链球菌引起的新感染。为了减少牧场放牧小母牛CM的发生率，需要在产犊前立即进行牛犊放牧。
An observational field study was conducted on 708 heifers in 30 spring-calving dairy herds in the Waikato region of New Zealand. The aim of the study was to describe patterns and effects of intramammary infection (IMI) and clinical mastitis ( CM) in the peripartum period. Mammary secretion samples for bacteriological testing were taken from all quarters approximately 3 wk before the planned start of the calving period and within 5 d following calving, in addition to quarters diagnosed with CM within 14 d of calving. Precalving IMI was diagnosed in 18.5% of quarters, and of these, coagulase-negative staphylococci were the predominant isolate (13.5% of quarters). Streptococcus uberis prevalence increased 4-fold to 10.0% of quarters on the day of calving compared with the precalving period. Prevalence of all pathogens decreased rapidly following calving. Clinical mastitis cases were predominantly associated with Strep. uberis (64%). The daily hazard of diagnosis was higher in heifers than in cows (0.06 vs. 0.02/d on d 1 postcalving, respectively), but was not different by d 5 (0.005 vs. 0.002, respectively) of lactation. Intramammary infection with a major pathogen was associated with an increased risk of removal from the herd ( 15 vs. 10% for infected and noninfected heifers, respectively) and somatic cell count > 200,000 cells/mL at subsequent herd tests ( 15 vs. 8%), but neither CM nor IMI were associated with reduced milk yield or milk solids production. Results suggest that bacterial species involved and the pattern of IMI prevalence in pasture-grazed peripartum heifers differ from those in other production systems. Further, mastitis control programs need to target major environmental pathogens causing precalving IMI, because new infections are likely before the onset of lactation, whereas existing detection and control measures are generally implemented after calving. Novel control programs that reduce new infections due to Strep. uberis immediately before calving are required to reduce the incidence of CM in pasture-grazed dairy heifers.