Moderation

Introduction

Several species of pathogenic bacteria may cause inflammation of the udder if they have succeeded in entering it; such an inflammation is called mastitis. It causes a decrease in milk yield and a change in milk composition, and a number of somatic cells in milk (especially polymorphonuclear leucocytes. A cell count of 5x 10⁵ often is taken as criterion for mastitis, but it is known to be not precise owing to other factors affect the cell count too, notably the individual cow, the stage of lactation and the age of the cow with their own mastititis history.

The incidence of udder infections may be influenced by the use of a milking machine in a different way:

a) mechanical transfer of pathogenic microorganisms from animal to animal

b) backflow of milk inside the milking system

c) backflow of milk between the cows

d) damage of the udder tissue particularly in the region of the teat head and the teat duct.

The inherent percentage of deceased udder quarters has been proposed to be smallest at a critical milk flow between 2 and 3 kg/min and additional desinfections from time to time [1].

Clinical udder infections are changing the the milk clearly requiring a medical treatment. The known pathogens are Escherichia coli, Bacillus cereus, Klebsiella, Pseudomonas aeruginosa, Clostridien, Nocardien, Streptococcen (Serogruppen A, D, C, G, L), Pneumococcen, Staphylococcen, Cornynea pyogenes, yeasts, mycoplasmen).

Subclinical mastitis might be developed from a clinical mastitis or remained on the subclinical status from the begin. The most widespread strains of subclinical mastitis are streptococcen and staphylococcen.

Judging by appearance it is often difficult to recognize a raw milk sample on subclinical mastitis although the chemical facts are gradually varying. All in the mammary gland synthetized constituents were absolutely but in addition to, some of the constituents coming unchanged from the blood. On subclinical mastitis the total casein, phosphor, riboflavin, and ascorbic acid were reduced. It is paralleled with an increase of catalase and chlor but with decreased lactose.

Diagnostically usable for an early test on mastitis might be the increase of catalase and chlor as well the alteration of lactose on mastitis.

The technological significance of milk from cows on mastitis is affected due to:

i. an increased content of chlor and natrium

ii. the reduction of fat-free dry matter (cheese production)

iii. impaired chymosin coagulation of milk plus a reduced discharge of the whey

iv. decreased heat stability of milk protein (increased values of serum albumin and immunglobulin)

v. the risk of the occurrence of the last bit of one inhibitor after a therapeutic treatment.

Introduction

The aflatoxins have closely related structures and form a unique group of highly oxiginated, heterocyclic compounds. They are produced by Aspergillus flavus and Aspergillus parasiticus, which are grown on foods (e.g. nuts,cereals, oilyseeds, and beans) under favorable temperatures and huminity conditiones, before or during harvest or improper storage. AFM₁, a metabolit of AFB₁ in mammals , may be found in the milk of animals ingesting feed contaminated with AFB₁, Afs B₁,B₂ and G₂ are classified as group 1 human carcinogens, whereas AFM₁ is classified as a Group 2B AF probable human carcinogen (Food and Agricultural Organization of UN and World Health Organization (1995). Codex Comittee on Food Additives and Contaminants, 28th Session, Manila Philippines, March 18-22, 1996, p 1-2).

The biological activities of aflatoxins enable them to function as potent toxins, carcinogens, teratogens and/or mutagens. All toxins in this family have a coumarin nucleus fused to a bifurano moiety and contain either a pentanone ring or a 6-membered lactone.

Their mode of operation is mostly not acute but it is based on long-term effects including repeated expositions: being harmful to both kidney and liver, development of cancer and wreck the immune system of humans and animals.

In the colloid-chemical method to determine the micellar surface hydrophobicity of native casein in milk Tween 80 may selectively block the hyrophobic area on the micellar surface allowing the differentiation between hydrophobic and hydrophilic areas, reliably. All aflatoxins are most surface actively and thus interfering the assay procedure. The question whether aflatoxins are present in a milk sample or not is resolved in the photometer. In the presence of aflatoxins the readings are showing never-ending great ranges of variation.

Introduction

Antibiotics have been in use in the dairy industry since the 1940s, mainly for the prevention or treatment of mastitis in lactating cattle [2]. However one of the major problems for the dairy industry is associated with antibiotic use has been the inhibitory effect of residues on acid production by starter lactic acid production by starter lactic acid bacteria. For example, penicillin residues at 0,1 and 0,05 units/mL have been found to cause a deterterioration in cheese quality and delayed acid production during cheese manufacture, respectively. In order to overcome potential residue problems for antibiotic detection have been developed into the industry.

It is evident from newer studies that many antibiotics used in the dairy industry significant inhibit starter bacteria at concentrations below the detectable limit of standard antibiotic screening assays.

Sub-detectable levels of antibiotic residues in milk for cheesemaking may be sufficient to inhibit starter activity in the cheese vats resulting in unexplained non-phage inhibition.

A milk- based diäteticum developed for hospitalized premature babies caused the death of one baby due to the presence of antibiotics. In the dairy, each delivery of bulked tank milk has been proved on antibiotics before.

Antibiotics are protein-bound toxins and thus with standard antibiotic screening not assessable [3].

Introduction

The concentration of a contaminant may be much diminished by the passage through the cow: substances may be broken down in the digestive tract; may be absorbed poorly or not at all in the intestinal mucosa and be excreted with the feces; they may take part in the metabolism and be broken down, for instance, in the liver; they may be excreted by the way of uninary tract, the lung, or the skin; and, finally, they may be excreted into the milk, through the glandular epithelium constituted a barrier of some resistance. The cow thus acts as a filter but, each compound has its own fade, of widely variable effectiveness; a well-known example is aflatoxin M₁ (a metabolite of aflatoxin B₁). Herbicides are occurring protein-bound with casein micelles in raw milk and the status of accumulation after 8 weeks. Cattles are known to be strict vegetarians and thus dependent on qualified fodder. In view of the long-term consumption, it means that is a chronic toxicity. Finally, the glandular epithelium is under strain and the milk secretion ceased increasingly.

References

• (1985) G Kielwein in: Guide to dairy science and milk hygiene. Significance of mechanical milk withdrawal for the development of udder diseases pp. 111 -113; Published by Paul Parey-Berlin and Hamburg.
• Hady PJ, Lloyd JW, Kaneene JB (1993) Antibacterial use in lactating cattle. J Am Vet Med Ass 203: 210-226.
• Mitchell JM, Griffiith MW, Mc Ewen SA, MacNab WB, YeeAJ (1989) Antimicrobial drug resiues in milk and meat. In: J Food prot 61: 742-756.