Introduction
In Hungary the most breded fish spices is the carp (Cyprinus carpio), which are feed/bred on fodder as well as on natural food of zooplanctons for the better bred. The grains used as animal feed in the fishing ponds are one of the main energy source is corn, what quality has deteriorated significantly over the past few years. Due to the warm up of the climate massive amount (or more and more) of Aspergillis mould appearing what is producing aflatoxin. The aflatoxin is a benzpiren type of multi conjugated, policyclic compound what is often occure in fodder as well (e.g. corn, oat). The aflatoxin is well know about its gene toxin and carcinogen behaviour (Klich, 2007). Once got into the human body it can causes acute / sub-acute inflammation of the liver, in severe cases, it leads to liver necrosis. It had been evinced that these toxins have harmful effect and high mortality rate not only in fish breding but in other animal breding as well (Murjani, 2003).
The objective of our study was to see what physiological effect is caused by theaflatoxin contaminated fodder in case of semi intensive carp bred. We have examinated 1+ and 2+ ages groups of fish inseparated small sized earthen ponds. In our experiments we have been examinating the development of the fish after 55 days of feeding with 20 µg/kg AFB1 (EU 574/2011/EU maximum 20 µg/kg AFB1) we have determined the toxin concentration from their blood samples and tissues (liver, flesh). We examined some of the vital organs (liver, reproductive organs) by using histological methods. After the feeding test the remaining individuals had been wintered, and in spring time new sample taking and examination was done.
Materials and methods
In the experiment the growth and prosperity of the individuals had been tested with test fishing by averaging an appropriate number of individuals groups. After the experimental period blood samples had been taken from the tail vein (vena caudalis) and the AFB1 concentration had been determined by using ELISA. A portion of the liver tissue was used for determination toxin (Toxi Watch Kit, ELISA) and the other part of the histological sections were made by hematoxylin-eosin, and was stained by periodic acid-Schiff reaction (PAS).
Results
In terms of results we can say that if the feeding is following the acceptable level of the Hungarian Feed Codex, there is no yield loss and conservation edge had been observed in either the control and in the infected groups or in age groups. During the hematological tests the aflatoxin concentration in blood plasma wasn`t significantly different between the aflatoxin contaminated corn-fed and control groups, the concentration of aflatoxin B1 is in the error tolerance of the measuring method. However in the liver tissue the toxin concentration is high, on average over 400 pg / g. Damage of cells, sometimes severe degenaration was observed in case of the aflatoxin fortified corn fed animals` liver cells during the different staining methods.
Conclusion
In our experiment we wanted to test what physiological changes can be observed in the different age groups of carp population agfter the maximum permitted aflatoxin concentration (20 µg / kg) was used in feeding. One of the most important observationwas that the blood is rapidly excreted aflatoxin B1 (identical results to the control), however in the tissues high concentrations of tested toxins accumulate.
Our study had been sponsored by:
VKSZ_12-1-2013-0078 project called "Complex break points in the development of competitiveness of the aquaculture sector" was realized in the frame of Program for R&D Excellence and Competitiveness Treaties within a consortium.
References
Klich M.A. (2007): Aspergillus flavus: the major producer of aflatoxin. Mol. Plant. Pathol., 8(6):713-22.
Murjani, G. (2003). Chronic aflatoxicosis in fish and its relevance.to uman health. Central Institute of Freshwater Aquaculture, India