MASTITIS - THE DISEASE UNDER ASPECTS OF MILK QUALITY AND HYGIENE

1. Inflammatory changes in the mammary gland influence the process of milk synthesis both quantitatively and qualitatively. The changes in t he constituents of milk affect the major components (lactose, fat, pro teins) as well as fatty acids, protein fractions, caseins, wh ey prote ins, anions and cations, conductivity, enzymes etc. With increasing nu mbers of somatic cells the growth of starter cultures in the milk may be adversely influenced. Renneting time and heat stability of the milk can be impaired. 2. The hygienic value of raw milk is determined by p athogenic microorganisms, saprophytic microorganisms, residues and con taminants. In the case of mastitis pathogenic microorganisms may occur , which are infectious also for men (e.g. B-streptococci, Escherichia coli strains) or which form under certain circumstances toxins (e.g. S taphylococcus aureus, Escherichia coli). 3. Residues due to the treatm ent of mastitis include primarily antimicrobials like antibiotics and sulfa drugs. The significance of antibiotic residues in milk has to be discussed under two important aspects: that relating to payment of mi lk on the basis of the technological quality (''inhibitors'') and that relating to public health and governed by food laws. 4. Concerning th e eff ect of antibiotic residues on human health a number of aspects h as to be considered (toxicological, microbiological and immunopatholog ical effects). From a technological point of view the sensitivity of t hermophilic and mesophilic starters to different antibiotics may vary widely. The fixation of maximum residue limits (MRLs) for a number of antimicrobials has led to the difficulty that a negative result of so- called inhibitor tests does not neccessarily indicate concentrations o f antimicrobials below the MRLs. A new and integrated system for the d etection of antimicrobials has to be developed, which takes technologi cal and toxicological aspects into Concern. 5. The use of disinfectant s for the dipping of teats before and after milking must also critical ly be evaluated. Not only the active ingredients (iodine, chlorhexidin e, chlorine etc.) have to be taken into consideration, but also other components used (e.g. detergents, additives). 6. The number of somatic cells in milk is an indicator of its qualitative/hygienic properties, which case reflect the given mastitis situation in the herd. The obje ctives of mastitis control measures should primarily cover the supply of milk with a low somatic cell content, which meets the qualitative a nd hygienic expectations of manufacturers and consumers.