Antibiotics in Foodstuffs

When we discuss different uses of antibiotics in agriculture as a hygienic problem, we have in mind above all the problem of assessing their residues in foods, or we are concerned with their effect on foods and the human organism resp.At present antibiotics are used in agriculture when they are added to fodder as protective substances in plant cultivation,and slso in the processing of meats where they are used as a preservative.We must not underrate either the problem of residues in milk following the treatment of mastitis in cows. Since 1950 successful trials were made where antibiotics were used for stimulating the growth of farm animals, particularly poultry and piga.The trials, where along with antibiotice vitamin B12 was administered, were most successful.The optimum concentration was 5-10mg.antibiotic per kg.fodder.This concentration has been raised since to 20-100mg.per kg.According to data reported in the literature the literature the weight increment of farm animals increases on an average by 10-20% due to the antibiotics. The mechanism of action of the antibiotic administered with fodder has not been elucidated completely so far.It is not clear whether a direct growth effect is involved or a nutritional effect via the influence exerted on the intestinal microflors.Most authors maintain,however,that the effect of antibiotics is due to the specific action on the intestinal microflora and that the activity of some toxin-producing microorganisms is reduced or eliminated and the nutrients are thus utilised more readily.It was for instance revealed that when sinultaneously with penicillin penicillinase was administered,which inactivated the penicillin,the growth effect was lacking. Some authors maintain, however,that by raising the sanitary standard in animal husbandry to an optimum level an equal effect can be obtained. The most remarkable stimulatory effect was obtained with antibiotics of the tetracycline series which are still used in most countries, incl.the CSSR.During the long-term administration of certain antibiotics a decrease of the growth effect of these substances was observed and therefore recently new antibiotics were introduced for feeding farm animals.Therefore at present in this country trials with bacitracin,oleandomycin and erythromycin for poultry feeding are conducted. As regards sensitization caused by antibiotics and also the possible induction of bacterial resistance,the problem of antibiotic residues in tissues of animals fed antibiotics is important.Broquist, Kohler,Anderson et al.found in sera of chicks fed antibiotics 0.014-0.061 gamma chlortetracycline