Gonçalves Juliano Leonel, Lyman Roberta L, Hockett Mitchell, Rodriguez Rudy, Dos Santos Marcos Veiga, Anderson Kevin L
Department of Population Health and Pathobiology,College of Veterinary Medicine,North Carolina State University,Raleigh, NC,USA.
Advanced Animal Diagnostics,Durham,NC,USA.
J Dairy Res. 2017 Aug;84(3):309-317. doi: 10.1017/S0022029917000267. Epub 2017 Jun 27.
This research study aimed to evaluate the use of the milk leukocyte differential (MLD) to: (a) identify quarter milks that are culture-positive; and (b) characterize the milk leukocyte responses to specific groups of pathogens causing subclinical mastitis. The MLD measures the absolute number and relative percentage of inflammatory cells in milk samples. Using the MLD in two dairy herds (170 and 172 lactating cows, respectively), we studied all lactating cows with a most recent monthly Dairy Herd Improvement Association somatic cell count (SCC) >200 × 103 cells/ml. Quarter milk samples from 78 cows meeting study criteria were analysed by MLD and aseptically collected milk samples were subjected to microbiological culture (MC). Based upon automated instrument evaluation of the number and percentage of inflammatory cells in milk, samples were designated as either MLD-positive or - negative for subclinicial mastitis. Positive MC were obtained from 102/156 (65·4%) of MLD-positive milk samples, and 28/135 (20·7%) of MLD-negative milk samples were MC-positive. When MC was considered the gold standard for mastitis diagnosis, the calculated diagnostic Se of the MLD was 78·5% (IC(95%) = 70·4 to 85·2%) and the Sp was 66·5% (IC(95%) = 58·6 to 73·7%). [corrected]. Quarter milks positive on MC had higher absolute numbers of neutrophils, lymphocytes and macrophages, with higher neutrophils% and lymphocytes% but lower macrophages%. The Log10 (N/L) ratios were the most useful ratio to differentiate specific subclinical mastitis quarters from healthy quarters. Use of the MLD on cows with monthly composite SCC > 200 × 103 cells/ml for screening at quarter level identified quarters more likely to be culture-positive. In conclusion, the MLD can provide an analysis of mammary quarter status more detailed than provided by SCC alone; however, the MLD response to subclinical mastitis was not found useful to specifically identify the causative pathogen.
本研究旨在评估乳白细胞分类计数（MLD）的用途，以：（a）识别培养阳性的乳房乳；以及（b）描述乳白细胞对引起亚临床乳腺炎的特定病原体组的反应。MLD可测量乳样中炎症细胞的绝对数量和相对百分比。在两个奶牛场（分别有170头和172头泌乳奶牛）中使用MLD，我们研究了所有最近一个月奶牛群改良协会体细胞计数（SCC）>200×10³个细胞/ml的泌乳奶牛。对符合研究标准的78头奶牛的乳房乳样进行MLD分析，并将无菌采集的乳样进行微生物培养（MC）。根据对乳中炎症细胞数量和百分比的自动仪器评估，将样本指定为亚临床乳腺炎的MLD阳性或阴性。从102/156（65.4%）的MLD阳性乳样中获得阳性MC，28/135（20.7%）的MLD阴性乳样为MC阳性。当将MC视为乳腺炎诊断的金标准时，计算得出的MLD诊断敏感性为78.5%（95%置信区间=70.4至85.2%），特异性为66.5%（95%置信区间=58.6至73.7%）。[已校正]。MC呈阳性的乳房乳中中性粒细胞、淋巴细胞和巨噬细胞的绝对数量较高，中性粒细胞%和淋巴细胞%较高，但巨噬细胞%较低。Log10（N/L）比值是区分特定亚临床乳腺炎乳房与健康乳房最有用的比值。对每月综合SCC>200×10³个细胞/ml的奶牛使用MLD进行乳房水平的筛查，可识别出更可能培养阳性的乳房。总之，MLD能够提供比单独的SCC更详细的乳腺乳房状态分析；然而，未发现MLD对亚临床乳腺炎的反应有助于特异性识别致病病原体。
