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Journal of Dairy Science Vol. 75 No. 7 1840-1848
© 1992 by American Dairy Science Association ®
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Prediction of Mastitis Using Milk Somatic Cell Count, N-Acetyl-ß-D-Glucosaminidase, and Lactose

L. M. Berning 1 and G. E. Shook 1

1 Dairy Science Department, University of Wisconsin, Madison 53706

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.

Key Words: mastitis • N-acetyl-ßbeta;-D-glucosaminidase • somatic cell count • lactose

Submitted on August 12, 1991
Accepted on March 2, 1992




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M. A. Wattiaux and K. L. Karg
Protein Level for Alfalfa and Corn Silage-Based Diets: I. Lactational Response and Milk Urea Nitrogen
J Dairy Sci, October 1, 2004; 87(10): 3480 - 3491.
[Abstract] [Full Text] [PDF]


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Copyright © 1992 by the American Dairy Science Association ®.