奶牛乳房炎主要致病菌在牛奶中的分布

Distribution of Major Pathogenic Bacteria of Cow Mastitis in Milk

[目的]观察奶牛乳房炎主要致病菌在牛奶中的分布情况。[方法]在牛奶中添加一定量的乳房炎致病菌金黄色葡萄球菌或大肠杆菌,于4℃分别静置8、12和24 h,牛奶被分割成上、中、下3等份。采用平板菌落计数法测定各部分牛奶中的细菌数。[结果]两种致病菌菌落数在牛奶中从下到上呈现上升趋势,且上部牛奶中的菌落数显著高于中、下部(P<0.001),中部与下部差异不显著。[结论]奶牛乳房炎致病菌经乳头管侵入后可以随牛奶中的脂肪滴上浮,进而侵入到乳腺的深层组织。

[Objective]To observe the distribution of major pathogenic bacteria of cow mastitis in milk in vitro.[Method]The Staphylococcus aureus and Escherichia coli were added into the milk.After standing for 8,12,24 h at 4 ℃,the milk were divided into upper,middle and lower three equal parts.The bacterial counts in the three parts of milk were respectively determined by plating colony-counting method.[Result]The counts of these two pathogenic bacteria in upper milk were higher than that in middle and lower milk significantly（P0.001）,and no significant difference was found between middle milk and lower milk.[Conclusion]The pathogenic bacteria of cow mastitis can be floating with fat droplet in milk and then invade into the deeper tissue of mammary gland.