Synergism between aflatoxin and ochratoxin A in broiler chickens.

A 2 X 2 factorial experimental design consisting of four treatments (0, 2.5 microgram/g aflatoxin, 2.0 microgram/g ochratoxin A, and 2.5 microgram/g aflatoxin + 2.0 microgram/g ochratoxin A) with six replicates of 10 birds each was used to evaluate the synergism between aflatoxin and ochratoxin A. The chicks (Hubbard X Hubbard) were maintained on these dietary treatments from hatching until they reached 3 weeks of age, when the experiment was terminated. The size of the liver, spleen, pancreas, and proventriculus was significantly (P less than .05) altered by the individual toxins; however, a synergistic effect on the size of these organs was not observed. The kidney and gizzard were sensitive to the coincident exposure to these mycotoxins and were significantly (P less than .05) enlarged. The kidney was the most sensitive organ to the combined toxicity of aflatoxin and ochratoxin A, and nephropathy was the most important characteristic of this interaction. The synergism between aflatoxin and ochratoxin A significantly (P less than .05) decreased growth rate and numerically increased mortality, demonstrating the enhanced toxicity of cocontaminated feed. Liver lipid levels were significantly (P less than .05) increased by aflatoxin and decreased by ochratoxin A. The interaction of both mycotoxins on this parameter was significant (P less than .05) and the combined effect demonstrates that ochratoxin A inhibited lipid accumulation normally induced by aflatoxin. The data show that toxicity-enhancing synergisms exist between mycotoxins and that symptom patterns are altered during multiple mycotoxicoses. The data also demonstrate that nephropathy is the primary effect of this interaction and, thus, is of diagnostic importance.