Politis I, Ng Kwai Hang K F, Giroux R N
Department of Animal Science, Macdonald College, McGill University, Quebec, Canada.
J Dairy Sci. 1989 Jul;72(7):1713-8. doi: 10.3168/jds.S0022-0302(89)79286-9.
A total of 367 milk samples were collected from 43 individual Holstein cows during 1 yr. Samples were analyzed for plasmin activity, total casein, alpha s-casein (alpha s1-casein + alpha s2-casein), beta-casein, kappa-casein, and SCC. Least squares analyses showed that SCC in milk were positively related (r = .62) to plasmin activity. An increase of SCC from 100,000 to 1,300,000/ml was associated with a 2.3-fold increase in plasmin activity (100 vs. 230 x 10(-6) units/ml). Increased plasmin activity was associated with advancing stage of lactation and older cows after appropriate adjustments were made for the effects of milk yield and SCC. Milk samples obtained in fall and winter were higher, but not significantly, in plasmin activity. Plasmin activity was also associated with major casein components and milk pH. Correlations coefficients between plasmin and alpha s-casein, beta-casein, and pH were -.14, -.27, and .19.
在1年的时间里，从43头个体荷斯坦奶牛身上共采集了367份牛奶样本。对样本进行了纤溶酶活性、总酪蛋白、αs-酪蛋白（αs1-酪蛋白+αs2-酪蛋白）、β-酪蛋白、κ-酪蛋白和体细胞数（SCC）的分析。最小二乘法分析表明，牛奶中的体细胞数与纤溶酶活性呈正相关（r = 0.62）。体细胞数从100,000/ml增加到1,300,000/ml与纤溶酶活性增加2.3倍相关（100对230×10⁻⁶单位/ml）。在对产奶量和体细胞数的影响进行适当调整后，纤溶酶活性增加与泌乳后期和年龄较大的奶牛有关。秋季和冬季采集的牛奶样本的纤溶酶活性较高，但差异不显著。纤溶酶活性还与主要酪蛋白成分和牛奶pH值有关。纤溶酶与αs-酪蛋白、β-酪蛋白和pH值的相关系数分别为-0.14、-0.27和0.19。
