Prediction of mastitis using milk somatic cell count, N-acetyl-beta-D-glucosaminidase, and lactose.
Prediction of mastitis using milk somatic cell count, N-acetyl-beta-D-glucosaminidase, and lactose.
复制标题
使用乳汁体细胞计数、N-乙酰-β-D-氨基葡萄糖苷酶和乳糖预测乳腺炎。
DOI：
10.3168/jds.s0022-0302(92)77943-0
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发表时间：
1992
影响因子：
3.5
通讯作者：
G. Shook
中科院分区：
文献类型：
--
作者：
L. Berning;G. Shook
本研究的目的是：1)检测乳中SCC、乳糖浓度和NAGase活性对细菌学状态变化的反应；2)建立预测乳腺细菌学状态的模型。数据包括10个商业牛群中的550头奶牛。自然对数NAGASE和对数细胞计数对细菌状态的变化最敏感。LOG NAGASE在区分主要病原体感染和次要病原体感染方面相对更有效，而LOG SCC更能区分感染和未感染类别。未转化的NAGase、SCC和乳糖对感染状态的反应要小得多。对牛群、哺乳次数、产奶量、乳酸菌数、乳酸酶和泌乳阶段的细菌状况进行Logistic回归分析。最不显著的变量在逐步过程中被删除。感染状态的最终预测因子是羊群、对数体细胞癌和对数Nagase。LOG SCC的作用是区分感染和非感染，而LOG Nagase则区分主要病原体和次要病原体。LOG NAGASE单独或与LOG SCC结合，大大增加了模型的检测能力。卡方拟合优度检验发现，观察到的感染概率和预测的感染概率之间没有显著差异。用群体平均值代替LOG SCC，用LOG NAGASE代替群体变量，导致预测的群体感染概率和观察到的群体感染概率之间存在显著差异。
The objectives of this work were 1) to examine the responsiveness of SCC, lactose concentration, and NAGase activity in milk to changes in bacteriological status and 2) to develop models for predicting bacteriological status of mammary glands. Data included 550 cows in 10 commercial herds. Natural logarithm NAGase and log cell count were most responsive to changes in bacterial status. The log NAGase was relatively more effective in identifying major from minor pathogen infections, whereas log SCC was better able to differentiate between infected and uninfected classes. Non-transformed NAGase, SCC, and lactose were considerably less responsive to infection status. Logistic regression of bacterial status on herd, lactation number, milk, log SCC, log NAGase, and stage of lactation was performed. The least significant variables were removed in a stepwise process. Final predictors of infection status were herd, log SCC, and log NAGase. The role of log SCC was to discriminate infection from no infection, whereas log NAGase discriminated major from minor pathogens. The log NAGase, alone or in combination with log SCC, added substantially to the detection power of the model. Chi-square goodness of fit tests found no significant differences between observed and predicted infection probabilities. Substitution of herd averages for log SCC and log NAGase for the herd variables resulted in significant differences between predicted and observed herd infection probabilities.