Detection of Subclinical Mastitis from On-Line Milking Parlor Data

A model, based on automatically collected data, was developed for detection of subclinical mastitis. The logistic regression model was based on the following variables: milk electrical conductivity, milk production, parity, and DIM. Subclinical mastitis was defined as a minimal period of 1 wk in which the SCC was >500 × 103 cells/ml. In contrast, periods were defined as healthy if the SCC was 6 electrical conductivity signals for high SCC. Based on these test characteristics, the model could be used as an initial screening tool in a herd with a high incidence of subclinical mastitis. Cows with a signal would have a higher probability of being diseased than the total population. In such herds. separation of milk from the signaled cows might be a possible management strategy to reduce the SCC in the bulk milk tank

DESIGN OF FIELD TRIALS FOR THE EVALUATION OF ANTIBACTERIAL PRODUCTS FOR THERAPY OF BOVINE CLINICAL MASTITIS.

In this paper, the design and statistical analysis of field trials for the evaluation of the efficacy of clinical mastitis therapeutics is covered. First, general issues underlying the design of clinical trials are reviewed. These include bias and confounding; randomization and blocking; and study objectives and choice of the corresponding hypothesis. Specific issues in the design of clinical mastitis trials are also discussed. Selection of subjects is discussed with regard to choice of experimental units, identification of reference population and study population, inclusion and exclusion criteria, and sample size calculation. Next, a section on treatment administration and evaluation of cure reviews treatment, blinding, choice of response measure, as well as compliance, withdrawal, and early termination. The statistical analysis section addresses possible statistical models, treatment of confounding, and fixed vs. random effects. In conclusion, well‐conducted clinical mastitis trials represent an invaluable, albeit difficult and expensive, effort to evaluate efficacy and tolerance under usual circumstances of use