Stoycho D. Stoev

INFLUENCE OF OCHRATOXIN A AND AN EXTRACT OF ARTICHOKE ON THE VACCINAL IMMUNITY AND HEALTH IN BROILER CHICKS

The combined effect of ochratoxin A (at diet levels of 130, 305 and 790 ppb) and penicillic acid was studied in 100 broiler chicks. Serological investigations revealed significantly lower haemagglutination inhibiting antibody titers in the experimental chicks immunized with vaccine against Newcastle disease. A statistically significant decrease of the body weight and the relative weight of lymphoid organs as well as a significant increase of the relative weight of kidneys and liver were seen. The main degenerative changes were observed in the proximal convoluted tubules in kidneys and slight degenerative changes were found in the hepatocytes. Degenerative changes and depletion of lymphoid cells were observed in the bursa Fabricii, thymus, spleen and Peyers patches of intestinal mucosa. Serum analyses revealed significant decreases of the total protein and cholesterol, and significant increases of the uric acid and glucose. Haematological analyses showed a slight anaemia, leucocytosis and slightly decompensated metabolic acidosis. A statistically significant protective effect of 5% total water extract of artichoke on humoral immune response (increase of haemaglutination inhibiting antibody titer), relative organ weight as well as on pathomorphological, haematological and biochemical changes induced by ochratoxin A, was established.

Susceptibility to secondary bacterial infections in growing pigs as an early response in ochratoxicosis.

Mycotoxic nephropathy was induced in twelve 14 kg pigs fed a dietary component, moulded by Aspergillus ochraceus and contributing ochratoxin A at 1 or 3 ppm for up to 3 weeks. Concurrently, salmonellosis arose spontaneously in all six animals treated at 3 ppm and all died between days 15 and 17. Two of the six pigs in the 1 ppm group died similarly but the rest, and all of six control animals, were unaffected. Clinical biochemistry and histology revealed changes typical of renal ochratoxicosis in all ochratoxin-treated pigs. Clinical and pathomorphological changes typical of salmonellosis were evident in all those that died and Salmonella choleraesuis was consistently isolated from their faeces and liver. In a further experiment at 1 ppm ochratoxin A in animals immunised against S. choleraesuis haemorrhagic diarrhoea resulted instead, associated with Serpulina hyodysenteriae and Campylobacter coli. There was concomitant evidence of immunosuppression and delayed response to immunization. For the first time, susceptibility to natural infectious disease has been demonstrated in pigs exposed to the immunotoxicity of ochratoxin A. Differentiation of biochemical and histological changes attributable to ochratoxicosis or to secondary disease may require reinterpretation of a classical description of experimental porcine ochratoxicosis.

Studies on some feed additives giving partial protection against ochratoxin A toxicity in chicks.

Significant protective effects of the feed additives: water extract of artichoke, sesame seed, Roxazyme-G and L-beta phenylalanine against the growth inhibitory effect of ochratoxin A (OTA) and associated pathomorphological changes were seen. Similarly, there was less OTA-induced decrease in serum total protein and increase of serum creatinine and urea in the chicks. Whereas OTA induced strong degenerative changes and an increase in weight of kidneys and liver as well as a decrease of the weight of lymphoid organs the additives variously gave protection against these changes. The protection of Roxazyme-G and sesame seed was better expressed in kidneys and liver, whereas the phenylalanine better protected the weight changes in gizzard, heart and the changes in differential WBC count. Notably, sesame seed gave strong protection against 5 ppm OTA-induced suppression of humoral immune response, for which artichoke also had some beneficial effect, whereas phenylalanine had hardly any effect.

Mycotoxic nephropathy in Bulgarian pigs and chickens: complex aetiology and similarity to Balkan Endemic Nephropathy

Spontaneous nephropathy in Bulgaria, which is observed frequently during meat inspection and which differs morphologically from the classical description of mycotoxic porcine/chicken nephropathy as made in Denmark, was found to have a multi-mycotoxic aetiology being mainly provoked by a combined effect of ochratoxin A, penicillic acid and fumonisin B1 in addition to a not-yet-known metabolite. Mean contamination levels of ochratoxin A were consecutively low (188.8 and 376.4 µg kg−1) in contrast to high contamination levels of fumonisin B1 (5564.1 and 3254.5 µg kg−1) and penicillic acid (838.6 and 904.9 µg kg−1) for 2006 and 2007, respectively. Some other mycotoxins with lower importance such as citrinin, penitrem A, etc., may also influence clinicopathological picture of this nephropathy. A heavy contamination with Gibberella fujikuroi var. moniliformis (Fusarium verticillioides) and Penicillium aurantiogriseum complex (mainly Penicillium polonicum) was observed in almost all examined feed samples coming from pig and chick farms with nephropathy problems from Bulgaria. In contrast, low contamination with Aspergillus ochraceus, Penicillium verrucosum and Penicillium citrinum was observed in the same feed samples and these species were isolated as very rare components of the mycobiota.

EXPERIMENTAL MYCOTOXICOSIS IN CHICKENS INDUCED BY OCHRATOXIN A AND PENICILLIC ACID AND INTERVENTION WITH NATURAL PLANT EXTRACTS

The combined toxic effect of ochratoxin A (OTA) and penicillic acid (PA) on the body mass, the weight and pathomorphology of some internal organs was studied in 85 broiler chickens fed a mouldy diet containing 130, 300 or 800 ppb OTA and 1000–2000 ppb PA. The main pathomorphological changes were cloudy swelling and granular degeneration in the epithelium and mononuclear cell proliferation and activation of capillary endothelium in the kidney and liver; degenerative changes and depletion of lymphoid cells in lymphoid organs (bursa of Fabricius, thymus and spleen) were also seen. Protective effects of 5% total water extract of artichoke and a new natural phytosubstance Rosallsat against these pathomorphological changes were observed. A significant decrease in body mass and relative weight of lymphoid organs was found after 6 weeks of exposure and a greater decrease after 10 weeks of exposure to OTA and PA, and a protective effect of artichoke extract and a slight effect of Rosallsat against that decrease was observed. A significant increase in relative weight of liver and kidneys was also observed as well as a protective effect of artichoke extract against that increase. The quantity of OTA and the percentage of positive samples were significantly lower in tissues of chickens treated with artichoke extract or Rosallsat in addition to OTA than in those treated with only OTA.

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.

Food safety and increasing hazard of mycotoxin occurrence in foods and feeds.

The possible hazard of mycotoxin occurrence in foods and feeds and some food-borne mycotoxicoses is reviewed. Management of the risk of mycotoxin contamination using some useful preventive measures against mycotoxin contamination of foods/feeds during pre- and post-harvesting periods is considered. The physical and chemical methods of mycotoxin decontamination of foods/feeds are briefly described. The use of various feed additives as a method for prevention of the adverse effects of mycotoxins is reviewed. The processing of various foods and feeds is considered in a view to possible mycotoxin decontamination. The necessary hygiene control and risk assessment in regard to mycotoxin contamination of foods and feeds in addition to some useful prophylactic measures are briefly described. A short reference is made concerning the most successful methods of veterinary hygiene control in order to prevent a possible entering of some mycotoxins in commercial channels with a view to human 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.

Experimental mycotoxic nephropathy in pigs provoked by a mouldy diet containing ochratoxin A and fumonisin B1

Mycotoxic nephropathy was induced in eighteen young pigs by mouldy diets containing 0.5 ppm ochratoxin A (OTA) and/or 10 ppm fumonisin B1 (FB1) for three months. While the most obvious damages provoked by OTA were seen in the kidneys as expressed by the strong degenerative changes in proximal tubules and fibrosis in kidneys, FB1 was found to induce an increase in permeability of vessels mainly in lung, brain, cerebellum or kidneys and slight to moderate degenerative changes in kidneys. Pathomorphological damages in pigs exposed to both mycotoxins simultaneously present a combination of the main lesions provoked by each mycotoxin alone being stronger in their expression. Biochemical investigations as expressed by the increase of serum creatinine, urea and enzyme activity of ASAT/ALAT and by the decrease of serum cholesterol, total protein, albumin and glucose were strongest in pigs exposed to both mycotoxins simultaneously as can be anticipated form the strongest lesions in the kidneys. Both mycotoxins and their combination were found to disturb powerfully humoral immune response in all experimental pigs as expressed by the strong decrease in antibody titer against Morbus Aujesky at days 21 and 35 after vaccination. Having in mind that the feed levels of the both mycotoxins as well as the exposure time and the pathological findings corresponded to those in some spontaneous cases of porcine nephropathy in Bulgaria and South Africa, it can be concluded that the same mycotoxins are involved in the observed field cases of that nephropathy.

Contamination with storage fungi of human food from Cameroon

In a mycological study, a total of 95 human food samples were investigated to evaluate the incidence of fungal contamination in Cameroon by conventional identification method and partly confirmed by DNA sequencing. The isolated fungal spp. were further studied to determine their toxigenic potentials. The investigation revealed the predominance of Aspergillus and Penicillium with 96% of samples contaminated with at least one species of these fungi, whereas the incidence of co-contamination of samples was 85%. Aspergillus flavus and Aspergillus parasiticus (Flavi section) were the most predominant species contaminating mainly maize and peanuts. In addition, P. crustosum and P. polonicum were the most common contaminants belonging to the genus Penicillium. On the other hand, A. ochraceus (Circumdati section) registered a low incidence rate of 5%, including other members of the Aspergillus group. Other members of the genera Rhizopus and Alternaria spp. were also registered in the study. A majority of fungal strains of A. ochraceus, A. parasiticus, P. crustosum and P. polonicum isolated were toxigenic, producing the mycotoxins tested for, while none was detected in cultures of A. fumigatus. The high incidence rate of fungi contamination coupled with their potentials in producing mycotoxins gives a strong indication that the samples tested may likely be contaminated with various mycotoxins. There is need for further study to assess the incidence of mycotoxins contamination in similar food samples.