Monitoramento de aflatoxinas, fungos toxigênicos e níveis de contaminação em matérias primas e alimentos balanceados. Aflatoxicose natural em cães no estado do Rio de Janeiro

Abstract

The commercial feed constitutes an important element in the pet industry in Brazil. Its composition includes cereal mixtures produced in farms such as sorghum, maize and some oily seeds. All feed destined to pets are supplemented with fats, vitamins, minerals, antirust and flours of diverse origins incorporated in some cases as pellets. When conditions of nutrients and moisture are adequate, fungal contamination could be present during pre and post harvest, storage, manufacture and processing of these ingredients. The filamentous stored grain fungi more commonly found include the species belonging to Aspergillus, Penicillium and Fusarium genera. They are able to produce different mycotoxins. Species of Aspergillus such as Aspergillus flavus, Aspergillus parasiticus and Aspergillus nomius are able to produce aflatoxins, considered as carcinogen type 1A. The pet foods have important amounts of cereals and therefore, they can concentrate important amounts of toxins. In dogs and cats the effects of mycotoxins are severe and can produce death, besides the loss of nutrients, to alter the organoleptic properties and to diminish the average life of the product in the market. On the other hand, the presence of toxicogenic species could indicate the contamination with several mycotoxins and this situation represents a potential risk for the animal health. On the basis of these antecedents the objectives of this work were 1) to characterize the mycoflora, 2) to detect the natural incidence of mycotoxins from raw materials and compound feed for dogs and 3) to establish parameters to prevent and/or to control micotoxicoses. A total of 230 samples (117 suspected foods to produce natural poisoning (AIN), 43 commercial foods (AC) of 3 different qualities, 70 ingredients of the production line (ALP)) of ingredients and rations destined to the feeding of dogs were analyzed. The fungal isolation was made by the surface spread method. The culture media were dicloran-rose-bengal-chloranphenicol agar (DRBC), dicloran-chloranphenicol 18% glicerol agar (DG18) and Nash-Snyder agar. The average of the number of colonies by triplicate was determined and it was expressed as colony forming units/gram of feed (UFC/g). AIN and some ALP (maize, ground maize, flour of sorghum, maize flour and gluten) obtained fungal counts over than 104 UFC/g. The AC samples were not over this value. Each strain was isolated and identified at the species level. The species belonging to the Aspergillus genera were predominant in all of the analyzed samples, having aflatoxicogenic species A. flavus/A. parasiticus those of greater frequency. These strains were evaluated in their ability to produce aflatoxins by the TLC method. The 100% of isolated strains of AIN, 80% of AC and 70% of ALP were able to produce aflatoxins at levels that varied from 2 and 66.25 ng/g. The natural incidence of aflatoxins in all feed samples was determined by high performance liquid chromatography (HPLC). AIN and some samples of ALP ingredients, mainly those containing maize, obtained aflatoxins levels over than 20 ppb. The hystopatological and biochemical studies of the affected animals organs demonstrated the death cause (aflatoxicosis), and were confirmed by the mycological studies: the fungal counts and aflatoxins levels were over the allowed ones by national and international regulations in use. The commercial feed of different qualities are feeds in conditions to be consumed, but have a potential risk if they are in inadequate storage conditions due to the aflatoxicogenic ability of the studied strains. As far as the ingredients and finished feed of the production line, those made up of maize did not fulfill the values of fungi and aflatoxins allowed by the legislation. Although the finished ration adjusts to the required regulation, probably by the processing, it presents a potential risk since more of 80% of the species of A. flavus, were able to produce aflatoxins B1 and B2. It is important then to emphasize the need to a suitable control of the used ingredients in the compound feed elaboration and the adequate environmental conditions to preserve the pet food of undesired fungal contamination and the consequent production of their mycotoxinas.