Date of Award


Document Type

Honors Thesis



First Advisor

Katherine Koudele


An infection in a cow's udder, also known as mastitis, has been a persistent problem for the U.S. dairy community. Mastitis not only decreases milk production, but also shortens the productive life of dairy cattle and can be fatal if left untreated. Mastitis presents in both subclinical and clinical forms - clinical is easy to diagnose and treat, whereas subclinical cases are much harder to detect as they present no physical symptons, yet can still become clinical in time. At the Andrews University Dairy, part of the milking system includes electrical conductivity (EC) determination which measures the ionic composition of a cow's milk as she is being milked. The milking management software (AFImilk) checks for increases in EC which may indicate subclinical mastitis; the system then alerts the milking parlor crew of elevated EC by a visual alarm and records the EC information on the cow's individual record. However, the dairy management team has found that the current EC system offers too many unnecessary or false alarms to be a helpful diagnostic tool, and that it merely promotes the desensitizing of workers to the presence of alarms. The purpose of this study is to determine, based on dairy records, the practical ability of EC to determine if a cow has mastitis and needs antibiotic treatment. Data on EC was collected from 89 cows at the A.U. Dairy that had experienced at least one episode of clinical mastitis in their current lactation. This data was processed during particular statistical parameters to determine false alarm rate, and ultimately, the data was analyzed using Bayes' Theorem to estimate the probability of a cow having mastitis given the presence of an alarm. Analyzing the accuracy and reliability of EC, this study has determined that the management's distrust of EC is well-founded, not misguided. Our results showed that, due an an exceptionally high number of false alarms and unpredicted mastitis events, EC is not a practical took for detecting clinical mastitis in the milking parlor.

Subject Area

Mastitis, Udder--Diseases.

Creative Commons License

Creative Commons Attribution-No Derivative Works 4.0 License
This work is licensed under a Creative Commons Attribution-No Derivative Works 4.0 License.