Timonen Anri A E, Katholm Jørgen, Petersen Anders, Mõtus Kerli, Kalmus Piret
Department of Clinical Veterinary Medicine, Institute of Veterinary Medicine and Animal Science, Estonian University of Life Sciences, Tartu, 51014, Estonia.
DNA Diagnostic A/S, Voldbjergvej 16, 8240 Risskov, Denmark.
J Dairy Sci. 2017 Aug;100(8):6554-6561. doi: 10.3168/jds.2016-12267. Epub 2017 Jun 7.
Subclinical mastitis is one of the major health problems in dairy herds due to decreased milk production and reduced milk quality. The aim of this study was to examine the within-herd prevalence of subclinical intramammary infection caused by Mycoplasma bovis and to evaluate associations between M. bovis and cow daily milk yield, udder health, and milk composition. Individual cow composite milk samples (n = 522) were collected from all lactating dairy cows in 1 Estonian dairy farm in November 2014. Daily milk yield, days in milk, and parity were recorded. Collected milk samples were analyzed for somatic cell count, milk protein, fat, and urea content. The presence of M. bovis, Staphylococcus aureus, Streptococcus agalactiae, and Streptococcus uberis in the milk samples was confirmed by quantitative PCR analysis. The within-herd prevalence of M. bovis was 17.2% in the study herd. No association was observed between days in milk and parity to the presence of M. bovis in milk. According to linear regression analysis, the daily milk yield from cows positive for M. bovis was on average 3.0 kg lower compared with cows negative for M. bovis. In addition, the presence of M. bovis in milk samples was significantly associated with higher somatic cell count and lower fat and urea content compared with milk samples negative for M. bovis. In conclusion, subclinical M. bovis intramammary infection is associated with decreased milk yield and lower milk quality.
亚临床型乳腺炎是奶牛群中的主要健康问题之一，会导致产奶量下降和牛奶品质降低。本研究的目的是调查牛支原体引起的亚临床型乳房内感染在牛群中的流行率，并评估牛支原体与奶牛日产奶量、乳房健康和牛奶成分之间的关联。2014年11月，从爱沙尼亚一个奶牛场的所有泌乳奶牛中采集了个体奶牛混合奶样（n = 522）。记录了日产奶量、泌乳天数和胎次。对采集的奶样进行体细胞计数、乳蛋白、脂肪和尿素含量分析。通过定量PCR分析确认了奶样中牛支原体、金黄色葡萄球菌、无乳链球菌和乳房链球菌的存在。在该研究牛群中，牛支原体在牛群中的流行率为17.2%。未观察到泌乳天数和胎次与奶中牛支原体的存在之间存在关联。根据线性回归分析，牛支原体检测呈阳性的奶牛的日产奶量平均比牛支原体检测呈阴性的奶牛低3.0千克。此外，与牛支原体检测呈阴性的奶样相比，奶样中牛支原体的存在与更高的体细胞计数以及更低的脂肪和尿素含量显著相关。总之，亚临床型牛支原体乳房内感染与产奶量下降和牛奶品质降低有关。
