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Objective: To evaluate the effect of a mastitis control program
(based on the mastitis prevention, elimination and monitoring) on
a herd udder health and milk quality status. Design: Field trial.
Animals: A large Holstein dairy herd of 1150 dairy cows. Procedure: 1) Evaluating the herd udder health status (by CMT and milk sampling from 19.34% of the milking cows for bacteriologic
culture, 2) Carrying out a control program (Consisted of: blitz treatment of Strep. ag., Post milking teat dipping by a 2.5% povidone Iodine solution with 5% glycerin, dry cow combination therapy,
systemic antibiotic therapy of late pregnant heifers, bedding
management, early detection, and good record keeping of clinical
cases as well as continuous monitoring of udder health and milk
quality by using bulk tank milk analysis), 3) Reevaluating the herd
udder health status (by CMT and milk sampling from 13.2% of the milking cows for culture).
Statistical analysis: Chi-square test, Analysis of variance,
Correlation coefficient, Fisher’s exact test.
Results: 1) Significant decrease in point prevalence, and incidence
rates of clinical mastitis, relative frequency of CMT-positive quarters,
relative frequency of samples from which Strep. ag., Staph. aureus
and Coliforms yielded and distribution of Strep. ag. and Staph.
aureus in clinical cases, 2) Significant increase in relative frequency of samples from which C. bovis yielded, relative frequency of samples yielding no microorganism and distribution of environmental
Streptococci, C. bovis and no growth in clinical cases, 3) Significant decrease followed by an increase in BTSCC (with an average of 225080 cells/mI), significant decrease in staph. count (with an
average of 2726 cfuJml) being noticed at the beginning of monitoring
only, and absence of significant differences in TBC, Coli. count and Strep. count (with averages of 56996, 17131 and 9948 cfulml,
respectively). In addition, in 76% of weekly bulk tank milk samples, Strep. ag. and Staph. aureus were not detected, 4) No correlation between the concentrations of major contagious pathogens and
herd BTSCC and a significant positive correlation between staph. count and BTSCC were observed.
Clinical implications: Seemingly, the achievement of furthur
improvement in mastitis status of the studied herd (i.e., eradication of Strep. ag. and effective control of Staph. aureus) would be subjected to: Continuous supervising of post milking teat disinfection
and shifting from teat spraying to dipping, monthly measurement of individual cow SCC, washing and disinfecting teat cup liners
between cows during milking and using more effective dry period
intramammary preparations as well. In addition to improve quality of herd milk, good udder preparation prior to milking is advised..