Bansal Baljinder K, Hamann Joern, Grabowskit Nils Th, Singh Krishan B
Institute for Food Quality and Safety, Department of Hygiene and Technology of Milk, University of Veterinary Medicine Hannover, Foundation Bischofsholer Damm 15, D-30173 Hannover, Germany.
J Dairy Res. 2005 May;72(2):144-52. doi: 10.1017/s0022029905000798.
Seven variables--electrical conductivity (EC), somatic cell count (SCC), N-acetyl-beta-D-glucosaminidase (NAGase), lactose, protein, fat and pH--were compared in four quarter milk fractions (MF1: strict foremilk; MF2: first 12-15 ml foremilk; MF3: subsequent 40-45 ml milk; MF4: strippings) and in one cow composite milk sample (CC) per cow. The study used 142 quarters from 37 lactating cows of the German Black Pied breed. To rule out any possible effect due to management, animal physiology and analytical procedures, the collection and processing of milk samples from each cow was repeated for three consecutive days, and the means of 3-d values were used. All variables were affected significantly by milk fraction and udder health. Compared with foremilk, EC, lactose and protein levels in strippings decreased, while SCC, NAGase and fat increased. The pH of foremilk and strippings did not differ significantly in healthy or in mastitic quarters. The difference between MF1 and MF2 was significant for EC in mastitic quarters, and for SCC in healthy quarters only. In general, mastitis resulted in a significant increase in EC, SCC, NAGase and protein but in a decrease in lactose and fat contents of milk in one or more of the milk fractions studied. Comparison of cow composite milk samples from healthy and mastitic cows revealed the significance (P < 0.01) of udder health for EC, SCC and lactose. Of the different parameters that can distinguish between healthy and mastitic quarters or cows, EC could be used to classify 76% of quarters and 73% of cows correctly, while the lactose content permitted correct identification of 81% of quarters and 76% of cows. NAGase and pH could be used to determine the status of 73% and 61% of quarters, respectively. In general, the correlation observed in strippings was higher than in foremilk for almost all the variables studied. Surprisingly, EC, SCC, NAGase and lactose in milk from healthy quarters of mastitic cows (with at least one mastitic quarter) differed significantly (P < 0.05) from those from healthy quarters of cows with all four healthy quarters, indicating an inconsistent effect of mastitic quarters on neighbouring healthy quarters (quarter interdependence).
对七个变量——电导率（EC）、体细胞计数（SCC）、N - 乙酰 - β - D - 氨基葡萄糖苷酶（NAGase）、乳糖、蛋白质、脂肪和pH值——在四组乳区奶样（MF1：严格意义上的初乳；MF2：最初的12 - 15毫升初乳；MF3：随后的40 - 45毫升奶；MF4：挤奶结束时的奶）以及每头奶牛的一份混合奶样（CC）中进行了比较。该研究使用了来自37头德国黑 pied 品种泌乳奶牛的142个乳区。为排除管理、动物生理和分析程序可能产生的任何影响，对每头奶牛的奶样采集和处理连续重复三天，并使用三天数据的平均值。所有变量均受到乳区和乳房健康状况的显著影响。与初乳相比，挤奶结束时的奶中EC、乳糖和蛋白质水平下降，而SCC、NAGase和脂肪增加。在健康或患乳腺炎的乳区中，初乳和挤奶结束时的奶的pH值差异不显著。在患乳腺炎的乳区中，MF1和MF2之间的EC差异显著，仅在健康乳区中SCC差异显著。总体而言，乳腺炎导致所研究的一种或多种乳区奶样中的EC、SCC、NAGase和蛋白质显著增加，但乳糖和脂肪含量下降。对健康奶牛和患乳腺炎奶牛的混合奶样进行比较发现，乳房健康状况对EC、SCC和乳糖具有显著影响（P < 0.01）。在可区分健康和患乳腺炎乳区或奶牛的不同参数中，EC可正确分类76%的乳区和73%的奶牛，而乳糖含量可正确识别81%的乳区和76%的奶牛。NAGase和pH值分别可用于确定73%和61%的乳区状态。总体而言，对于几乎所有研究的变量，在挤奶结束时的奶中观察到的相关性高于初乳。令人惊讶的是，患有乳腺炎奶牛（至少有一个患乳腺炎乳区）健康乳区的奶中的EC、SCC、NAGase和乳糖与四分之一乳区都健康的奶牛健康乳区的奶中的这些指标存在显著差异（P < 0.05），这表明患乳腺炎的乳区对相邻健康乳区有不一致的影响（乳区相互依存）。
