Complex etiology, prophylaxis and hygiene control in mycotoxic nephropathies in farm animals and humans

Natural feed additives and bioactive supplements versus chemical additives as a safe and practical approach to combat foodborne mycotoxicoses

This review highlights the possible hazard of mycotoxins occurrence in foods and feeds in regards to foodborne diseases. The possible management of the risk of contamination of foods and feeds with mycotoxins by using natural feed additives, protecting against deleterious effects of mycotoxins or inhibiting the growth of fungi and mycotoxin production, is deeply investigated in the available literature and some effective measures for safe utilization of mycotoxin contaminated feed/food are proposed. The biological methods of decontamination, degradation or biotransformation of mycotoxins are deeply analyzed and discussed. Some natural antagonists against target fungi are also reviewed and a comparison is made with conventional fungicides for ensuring a safe prevention of mycotoxin contamination. The most common and useful chemical methods of mycotoxins decontamination of agricultural commodities or raw materials are also investigated, e.g., chemical additives inactivating or destroying and/or adsorbing mycotoxins as well as chemical additives inhibiting the growth of fungi and mycotoxin production. The practical use and safety of various kind of feed/food additives or herbal/biological supplements as possible approach for ameliorating the adverse effects of some dangerous mycotoxins is deeply investigated and some suggestions are given. Various possibilities for decreasing mycotoxins toxicity, e.g., by clarifying the mechanisms of their toxicity and using some target antidotes and vitamins as supplements to the diet, are also studied in the literature and appropriate discussions or suggestions are made in this regard. Some studies on animal diets such as low carbohydrate intake, increased protein content, calorie restriction or the importance of dietary fats are also investigated in the available literature for possible amelioration of the ailments associated with mycotoxins exposure. It could be concluded that natural feed additives and bioactive supplements would be more safe and practical approach to combat foodborne mycotoxicoses as compared to chemical additives.

Foodborne Diseases Due to Underestimated Hazard of Joint Mycotoxin Exposure at Low Levels and Possible Risk Assessment

The subject of this review paper is to evaluate the underestimated hazard of multiple mycotoxin exposure of animals/humans for the appearance of foodborne ailments and diseases. The significance of joint mycotoxin interaction in the development of foodborne diseases is discussed, and appropriate conclusions are made. The importance of low feed/food levels of some target mycotoxins co-contaminations in food and feedstuffs for induction of target foodborne mycotoxicoses is also studied in the available literature. The appropriate hygiene control and the necessary risk assessment in regard to possible hazards for animals and humans are also discussed, and appropriate suggestions are made. Some internationally recognized prophylactic measures, management of the risk, and the necessity of elaboration of new international regulations in regard to the maximum permitted levels are also carefully discussed and analysed in the cases of multiple mycotoxin contaminations. The necessity of harmonization of mycotoxin regulations and control measures at international levels is also discussed in order to facilitate food trade between the countries and to ensure global food safety.

New Evidences about the Carcinogenic Effects of Ochratoxin A and Possible Prevention by Target Feed Additives

A review of the carcinogenic effects of ochratoxin A (OTA) on various tissues and internal organs in laboratory and farm animals is made. Suggestions are made regarding how to recognize and differentiate the common spontaneous neoplastic changes characteristic for advanced age and the characteristic neoplasia in different tissues and organs in laboratory animals/poultry exposed to OTA. The synergistic effects of OTA together with its natural combination of penicillic acid are also investigated regarding possible carcinogenic effects. The malignancy and the target location of OTA-induced neoplasia is studied. The sex-differences of such neoplasia are investigated in the available literature. The time of appearance of the first neoplasia is investigated in long-term carcinogenic studies with OTA-treated animals. The possibility of target feed additives or herbs to counteract the toxic and carcinogenic effects of OTA is studied in the available literature. Some effective manners of prophylaxis and/or prevention against OTA contamination of feedstuffs/foods or animal production are suggested. The suitability of various laboratory animals to serve as experimental model for humans with regard to OTA-induced tumorigenesis is investigated.

Long term preliminary studies on toxic and carcinogenic effect of individual or simultaneous exposure to ochratoxin A and penicillic acid in mice

Carcinogenic effects of ochratoxin A (OTA) on liver, kidneys, intestine, muscles and subcutaneous tissue of BALB/c albino mice divided in three experimental and one control groups (30 mice in each group - 15 males and 15 females) and exposed to 10 ppm OTA and/or 50-60 ppm penicillic acid (PA) in the diet were seen. A total 22 neoplasias were found to be induced in the mice during 20 months' experimental period. Among them 14 were malignant and 8 benign. The number of neoplasias was significantly higher in the mice treated simultaneously with OTA and PA (14) compared to those in mice treated with OTA only (8). The number of malignant neoplasias was also higher (14) compared to benign neoplasias (8). Nine of a total fourteen malignant neoplasis and five of a total eight benign neoplasias were seen in the male mice. Pathological changes in mice after two weeks' experimental period were characterized by degenerative changes in kidneys, liver and gastrointestinal tract, which were better expressed in the mice exposed simultaneously to OTA and PA. A strong synergistic effect was found between OTA and PA towards tumorogenesis. It seems that mice are not a good experimental model for humans with regard to OTA-induced tumourigenesis, because the target organ of OTA-toxicity in humans or pigs is mainly the kidney, but not the liver, intestines, subcutaneous tissue or muscles as seen in this study.

Foodborne mycotoxicoses, risk assessment and underestimated hazard of masked mycotoxins and joint mycotoxin effects or interaction

The existing hazard of joint mycotoxin exposure of animals/humans and the significance of masked mycotoxins in foods or feeds and their respective contributions to the development of some food born mycotoxicoses is briefly reviewed. The importance of joint mycotoxin interaction in the complex etiology of some foodborn mycotoxicoses is covered in depth. The toxicity of low contamination levels of some combinations of mycotoxins ingested often by farm animals was carefully studied. The appropriate hygiene control and the necessary risk assessment in regard to mycotoxin contamination of foods and feeds are briefly analyzed and some useful prophylactic measures and management of the risk of mycotoxin contamination, in addition to tolerable daily intakes are also described. A reference is also made to the most suitable methods of veterinary hygiene control in some practical situations in order to prevent mycotoxins contaminating commercial food commodities and endangering public health.

Porcine/chicken or human nephropathy as the result of joint mycotoxins interaction

A survey was made of the literature concerning the occurrence and incidence of mycotoxic nephropathy in pigs and chicks in different countries. Various etiological factors contributing to the development of the disease were considered. The main nephrotoxic fungi as well as the specific conditions for their growth and toxins production were briefly described. A survey was made about the most frequent nephrotoxic fungal contaminants in various feedstuffs from plant origin. In addition, their natural quantities and importance for development of mycotoxic porcine/chick nephropathy (MPN/MCN) are also explored. In addition, a survey was made of the feedstuffs representing the most favorable environment for nephrotoxic fungal growth as well as the most favorable storehouse conditions for this fungal growth were shortly described. The significance of some underestimated fungal species, which can provoke kidney damage, was studied. The importance of joint mycotoxin interaction and newly identified fungal metabolites in the complex etiology of mycotoxic nephropathy ranged in some countries is deeply investigated. The toxicity of the low contamination levels of some combinations of mycotoxins often administered by pigs and chicks in the practice was carefully studied.

Estimation of multi-mycotoxin contamination in South African compound feeds

A total of 92 commercial compound feeds from South Africa were investigated for various mycotoxins. The data reveal the highest incidence of feed contamination for fumonisins (FB) (range: 104-2999 µg/kg) followed by deoxynivalenol (DON) (range: 124-2352 µg/kg) and zearalenone (ZEA) (range: 30-610 µg/kg). The incidence of ochratoxin A (OTA) and aflatoxins (AF)-contaminated samples were generally low, i.e., 4% and 30% of samples with levels ranging between 6.4 and 17.1 µg/kg (mean: 9.9 µg/kg) for OTA and 0.2 to 71.8 µg/kg (mean: 9.0 µg/kg) for AF. No samples contained T-2 toxin or HT-2 toxin. However, all samples analyzed were contaminated with at least one mycotoxin with a majority containing several mycotoxins. In particular, 3 of 4 positive samples mainly cattle feeds that had relatively high contents of OTA (ranging from 7 to 17.1 µg/kg) also contained high amounts of AF (>27.5 µg/kg) together with FB, DON and ZEA. Apart from a few samples, the levels of mycotoxins may be regarded as safe for livestock production in South Africa. However, the persistent co-occurrence of mycotoxins in samples, especially those at high concentrations, i.e., AF and OTA, together with other mycotoxins studied, may elicit synergistic or additive effects in animals. This should raise concern as multiple contaminations may pose a risk to livestock production and health.

Studies on carcinogenic and toxic effects of ochratoxin A in chicks

Carcinogenic/toxic effects of ochratoxin A (OTA) in various internal organs of Plymouth Rock chicks were determined. The number of OTA-induced neoplasms was similar in chicks given 25 ppm L-β-phenylalanine (PHE) in addition to 5 ppm OTA compared to chicks given only 5 ppm OTA, which showed that PHE cannot be used as a real protector against the carcinogenic or toxic effects of OTA in chicks. OTA was found to provoke strong degenerative changes in liver and kidneys, degenerative changes and depletion of cells in lymphoid organs, oedematous and degenerative changes in the brain, muscular haemorrhages and fatty changes in the bone marrow. The target organs for carcinogenic effect of OTA in chicks were found to be kidneys and liver.

Ochratoxin A and aristolochic acid involvement in nephropathies and associated urothelial tract tumours

This review addresses the unresolved aetiology of several nephropathies and associated upper tract tumours diagnosed all over the world, but especially in the Balkan regions. Studies conducted over the last 35 years point to mycotoxins, mainly ochratoxin A (OTA) as the main culprit. Recent theories however have implicated aristolochic acids (AA). The aim of this review is to put forward arguments in favour of the mycotoxin theory and to show the incoherence of the AA theory. It discusses the differences between the epidemiology of Balkan endemic nephropathy (BEN) and aristolochic acid nephropathy (AAN); OTA and AA carcinogenicity; clinical and pathological effects induced by OTA and AA; sources of OTA contamination (food, air, drinking water); OTA- and AA-DNA adduct formation; the role of genetic polymorphisms; and the risk for young children.

Studies on some feed additives and materials giving partial protection against the suppressive effect of ochratoxin A on egg production of laying hens

The protective effects of various feed supplements against the harmful effect of ochratoxin A on egg production and sexual maturation of two-weeks old Plymouth Rock female chicks designed for laying hens were studied. A significant protective effect of the feed additives or materials: water extract of artichoke (WEA), sesame seed (SS), Roxazyme-G (RG) and l-beta phenylalanine (PHE) against the suppressive effect of ochratoxin A (OTA) on egg production of laying hens was found. A similar protection was also seen on the toxic effect of OTA on various internal organs of the same hens. A significant protection was found against the decrease of the weight or the quantity of eggs as well as against the delay of the beginning of the laying period of chicks, both of which were provoked by ochratoxin A. These protective effects were strongest in chicks treated with SS or WEA, but were slightest in chicks treated with l-beta PHE.

Complex etiology and pathology of mycotoxic nephropathy in South African pigs

Spontaneous nephropathy in pigs seen in South Africa was found to have multi-mycotoxic etiology involving several mycotoxins such as ochratoxin A (OTA), penicillic acid (PA) and fumonisin B1 (FB1) in addition to a not yet identified mycotoxin. Contamination levels of OTA were comparatively low (67-75 μg/kg) in contrast to high contamination levels of FB1 (5,289-5,021 μg/kg) and PA (149-251 μg/kg). A heavy contamination with Gibberella fujikuroi var. moniliformis and Penicillium aurantiogriseum complex (mainly P. polonicum) was observed in the fed forages in contrast to the light contamination with Aspergillus ochraceus, P. verrucosum and P. citrinum. The pathomorphological picture of this nephropathy was found to differ from the classical description of mycotoxic porcine nephropathy as originally made in Scandinavia by the extensive vascular changes.

Changes in metallothionein level in rat hepatic tissue after administration of natural mouldy wheat

Mycotoxins are secondary metabolites produced by microfungi that are capable of causing disease and death in humans and other animals. This work was aimed at investigation of influence of mouldy wheat contaminated by pathogenic fungi producing mycotoxins on metallothionein levels in hepatic tissue of rats. The rats were administrating feed mixtures with different contents of vitamins or naturally mouldy wheat for 28 days. It was found that the wheat contained deoxynivalenol (80 +/- 5 microg per kg of mouldy wheat), zearalenone (56 +/- 3 microg/kg), T2-toxin (20 +/- 2 microg/kg) and aflatoxins as a sum of B1, B2, G1 and G2 (3.9 +/- 0.2 microg/kg). Rats were fed diets containing 0, 33, 66 and 100% naturally moulded wheat. Control group 0, 33, 66 and 100% contained vitamins according to Nutrient Requirements of Rats (NRC). Other four groups (control group with vitamins, vit33, vit66 and vit100%) were fed on the same levels of mouldy wheat, also vitamins at levels 100% higher than the previous mixtures. We determined weight, feed conversion and performed dissection to observe pathological processes. Changes between control group and experimental groups exposed to influence of mouldy wheat and experimental groups supplemented by higher concentration of vitamins and mouldy wheat were not observed. Livers were sampled and did not demonstrate significant changes in morphology compared to control either. In the following experiments the levels of metallothionein as a marker of oxidative stress was determined. We observed a quite surprising trend in metallothionein levels in animals supplemented with increased concentration of vitamins. Its level enhanced with increasing content of mouldy wheat. It was possible to determine a statistically significant decline (p<0.05) between control group and groups of animals fed with 33, 66 and 100% mouldy wheat. It is likely that some mycotoxins presented in mouldy wheat are able to block the mechanism of metallothionein synthesis.