Diagnosis of Intramammary Infection by the Electrical Conductivity of Milk
Fernando, Ranjit Simon Ignatius
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Permalink
https://hdl.handle.net/2142/71720
Description
Title
Diagnosis of Intramammary Infection by the Electrical Conductivity of Milk
Author(s)
Fernando, Ranjit Simon Ignatius
Issue Date
1983
Department of Study
Dairy Science
Discipline
Dairy Science
Degree Granting Institution
University of Illinois at Urbana-Champaign
Degree Name
Ph.D.
Degree Level
Dissertation
Keyword(s)
Agriculture, Animal Pathology
Abstract
This study consisted of two experiments. In the first, quarter samples of foremilk, primary milk, and strippings were obtained from twelve cows after 3, 6, 9, 12, and 15 h milking intervals.
Effect of milking interval was significant for all variables. Conductivity, chloride, sodium and somatic cells declined until 9 h. These responses except cells increased between 9 and 15 h. Lactose followed the opposite trend. Changes were in both uninfected and infected quarters, but were more pronounced in the latter. Strippings was most sensitive to increased conductivity by infection, and was affected least by milking interval. Results suggested that epithelial permeability was increased during milk ejection.
In the second experiment, efficacy of using laboratory and in-line measurements of conductivity was evaluated. Samples were from 75 cows (588 samples manually, and 3316 in-line).
Conductivity of strippings was more accurate in detecting microbial infection than that of foremilk or bucket milk. Accuracy of detecting uninfected quarters and quarters infected by primary pathogens was 90% and 84.5% respectively, and was with a threshold of 5800 (mu)mho at 25(DEGREES)C. Greater accuracy of detecting mastitis was obtained with conductivity than with chloride, sodium, potassium, bovine serum albumin, lactose, or cell count.
In-line conductivity was determined on quarter milk every 50 (mu)sec, and the highest of these retained every 6 sec. An average of the 10 highest of these values resulted in greatest accuracy of predicting microbial infection, compared to an average of the 5 highest values, or an overall average. Data during the last 1/3 of milking were more reliable than that from the first or second thirds of milking. With a threshold of 8000 (mu)mho/cm, false positives and negatives were 10% and 16.6%. False negatives were reduced to 5.5% by use of a multiple threshold where a quarter was positive when 2 of 4 values exceeded 8000 (mu)mho/cm. Conductivity holds considerable promise as a basis for development of automatic screening for subclinical mastitis.
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