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Standard methods to diagnose Clinical Mastitis (CM) are clinical udder examination, drawing milk samples and cytological and bacteriological examination of milk. Clinical examination especially palpation of the udder is a simple and expeditious way to diagnose CM. Scoring systems for udder firmness to examine effects of changes of milking management on animal welfare were developed. In addition, there are some studies where udder firmness was measured using a technical device to obtain values on a continuous scale. However, data on repeatability or validity of specific methodology of udder examination are rare.
The object of this study was to evaluate differences in udder firmness before and after milking in cows with CM and clinically healthy cow as a potential diagnostic tool.
The study was conducted on a commercial dairy farm housing approximately 1,200 Holstein Friesian dairy cows with an annual milk yield of 10,147 kg. Cows were milked 3 times a day. 43 cows with signs of CM and 91 control cows without CM were included into the study. Starting at the day of occurrence of CM udder firmness was measured at 9 days (d0 to d7 and d 14) before and after milking. Udder firmness was measured via palpation and a Dynamometer (Penefel DTF14). Furthermore, milk samples as well as length and width of quarters were taken on d0, d7 and d14.
The range of udder firmness values measured with the Dynamometer was 0.30 kg to 11.39 kg. Udder firmness decreased significantly in both groups due to milking (p ≤ 0.05). But throughout the whole study period, udder firmness after milking in cows with CM was significantly higher than in cows without CM (1.05 kg vs 0.64 kg, p ≤ 0.05). In a ROC analysis, udder firmness exceeding 1.103 kg after milking was indicative for a CM (sensitivity 76%, specificity: 86.4%; AUC 0.848).
We could demonstrate that udder firmness can be used as a diagnostic tool for CM. The difference between cows with CM and without CM was apparent even 14 days after the occurrence of the CM.