Gerardi Gabriele, Bernardini Daniele, Azzurra Elia Carla, Ferrari Vanni, Iob Luciano, Segato Severino
Department of Veterinary Clinical Science, University of Padua - 35020 Legnaro (PD), Italy.
J Dairy Res. 2009 Nov;76(4):411-7. doi: 10.1017/S0022029909990057. Epub 2009 Jul 29.
Mastitis is the most frequent and costly disease in dairy herds, as it negatively affects yield and milk quality. The presence of clinical mastitis is quite easy to asses, whereas the diagnosis of the subclinical form can be more difficult and requires laboratory assays. Somatic cell count (SCC) is widely used as a rapid and low-cost indicator of mastitis, even if is not useful in discriminating between the clinical and subclinical form. As amyloid A has been investigated as a marker of mastitis, the aim of this study was to assess the potential value of measuring amyloid A in serum and milk and the correlation with SCC in the diagnosis of subclinical mastitis. The reliability of two different ELISA kits for the measurement of amyloid A in milk was also tested. During a 1-month trial period, 21 cows were assigned to three experimental groups according to their health status: 6 cows with clinical mastitis (CM), 10 cows with subclinical mastitis (SM) and 5 healthy cows (HE). Amyloid A was measured both in serum (SAA) and in quarter milk samples (mAA) with a serum ELISA kit, and in quarter milk samples (MAA) with a milk ELISA kit. SCC, total microbial count (TMC) and bacterial examination of the milk were also carried out. After a log transformation, the data were submitted to ANOVA and linear regression. TMC was significantly higher in cows with clinical mastitis, while no differences were observed between the other two experimental groups. SCC and MAA levels were significantly different among the three groups. mAA concentrations were similar between cows with subclinical and clinical mastitis, and SAA was not affected by mastitis. A significant correlation between SCC and MAA or mAA was detected, while no correlation was recorded between SAA and mAA. A close relationship between MAA and mAA was noticeable even at low concentrations, suggesting MAA as a potential physiological marker of subclinical mastitis.
乳腺炎是奶牛群中最常见且成本最高的疾病，因为它会对产奶量和牛奶质量产生负面影响。临床乳腺炎的存在很容易评估，而亚临床型乳腺炎的诊断可能更困难，需要实验室检测。体细胞计数（SCC）被广泛用作乳腺炎的快速且低成本指标，尽管它在区分临床型和亚临床型乳腺炎方面并无用处。由于淀粉样蛋白A已被研究作为乳腺炎的标志物，本研究的目的是评估在血清和牛奶中测量淀粉样蛋白A的潜在价值以及与SCC在亚临床乳腺炎诊断中的相关性。还测试了两种不同的酶联免疫吸附测定（ELISA）试剂盒用于测量牛奶中淀粉样蛋白A的可靠性。在为期1个月的试验期内，根据健康状况将21头奶牛分为三个实验组：6头患有临床乳腺炎（CM）的奶牛、10头患有亚临床乳腺炎（SM）的奶牛和5头健康奶牛（HE）。使用血清ELISA试剂盒在血清（SAA）和四分体牛奶样本（mAA）中测量淀粉样蛋白A，并使用牛奶ELISA试剂盒在四分体牛奶样本（MAA）中测量。还进行了SCC、总微生物计数（TMC）和牛奶的细菌检查。经过对数转换后，数据进行方差分析和线性回归。临床乳腺炎奶牛的TMC显著更高，而其他两个实验组之间未观察到差异。三组之间的SCC和MAA水平存在显著差异。亚临床和临床乳腺炎奶牛的mAA浓度相似，且SAA不受乳腺炎影响。检测到SCC与MAA或mAA之间存在显著相关性，而SAA与mAA之间未记录到相关性。即使在低浓度下，MAA和mAA之间也存在密切关系，表明MAA作为亚临床乳腺炎的潜在生理标志物。
