Johansson Monika, Lundh Åse, de Vries Ruben, Sjaunja Kerstin Svennersten
Department of Molecular Sciences,Swedish University of Agricultural Sciences,PO Box 7015,SE-750 07 Uppsala,Sweden.
Department of Animal Nutrition and Management,Swedish University of Agricultural Sciences,PO Box 7024,SE-750 07 Uppsala,Sweden.
J Dairy Res. 2017 May;84(2):154-158. doi: 10.1017/S0022029917000140.
The objective of the studies reported in this research communication was to investigate differences in composition and enzymatic activities in bulk milk samples provided from Swedish dairy farms with different management systems, i.e. automated (AMS) and conventional milking systems (CMS). A bulk milk sample was collected from each of 104 dairy farms, 51 using AMS and 53 using CMS, located in the same geographical region. Sampling took place within two consecutive days during the indoor period (October). Milk samples were analysed for contents of total fat and protein, free fatty acids (FFA), caseins and whey proteins, somatic cell count (SCC), pH, plasmin and plasminogen derived activities, and total proteolysis. Our results showed a lower protein content and higher SCC in bulk milk from AMS herds compared with milk from CMS herds. Plasmin, plasminogen and total plasmin/ plasminogen derived activities were lower in milk from AMS herds but despite this, total casein and the ß-casein fraction as % of total protein were lower in milk from AMS herds than in milk from herds using CMS. Total proteolysis was higher in milk from AMS herds, suggesting that other proteases than plasmin, e.g. cellular and bacterial proteases, contributed to the degradation of casein. This was supported by a positive correlation between SCC and total proteolysis (P < 0·01), as well as a negative correlation between total proteolysis and ß-casein fraction (P < 0·05). In conclusion, comparing the quality of bulk milk from commercial dairy herds using AMS and CMS, respectively, several differences were observed, suggesting a significant effect from management system.
本研究通讯中报道的这些研究的目的是调查来自瑞典不同管理系统（即自动化挤奶系统（AMS）和传统挤奶系统（CMS））的奶牛场的原料奶样品在成分和酶活性方面的差异。从位于同一地理区域的104个奶牛场中各采集一份原料奶样品，其中51个使用AMS，53个使用CMS。在室内饲养期（10月）的连续两天内进行采样。对牛奶样品进行了总脂肪和蛋白质含量、游离脂肪酸（FFA）、酪蛋白和乳清蛋白、体细胞计数（SCC）、pH值、纤溶酶和纤溶酶原衍生活性以及总蛋白水解的分析。我们的结果表明，与CMS牛群的牛奶相比，AMS牛群的原料奶蛋白质含量较低，SCC较高。AMS牛群牛奶中的纤溶酶、纤溶酶原和总纤溶酶/纤溶酶原衍生活性较低，但尽管如此，AMS牛群牛奶中的总酪蛋白和β-酪蛋白占总蛋白质的比例低于使用CMS的牛群的牛奶。AMS牛群牛奶中的总蛋白水解程度较高，这表明除纤溶酶外的其他蛋白酶，如细胞和细菌蛋白酶，对酪蛋白的降解有贡献。SCC与总蛋白水解之间的正相关（P<0.01）以及总蛋白水解与β-酪蛋白比例之间的负相关（P<0.05）支持了这一点。总之，分别比较使用AMS和CMS的商业奶牛群的原料奶质量，观察到了一些差异，表明管理系统有显著影响。
