Toxicity of cyanuric acid to broilers on hepatic and renal health with and without melamine

The purpose of this study was to evaluate the toxicity potential of cyanuric acid (CYA) and a combination of melamine (MEL) and CYA in broilers. A total of 1200 male COBB 500 broilers were randomly allocated into 1 of 10 treatment groups by a 5 x 2 factorial design in a 42-d experiment. The dietary treatments were as follows: T-1 to T-5: basal diets with 0, 10, 20, 33.3, and 50 mg CYA per kg diet; T-6 to T-10: basal diet with CYA regimens similar to T-1 to T-5 but with 100 mg MEL per kg diet. There were 6 replication pens with 20 chicks per pen. No differences were observed in alanine transaminase (ALT) and aspartate aminotransferase (AST) activities. But on d 22, uric acid (UA) and creatinine (Crea) concentrations were significantly greater when birds were fed CYA at 33.3 mg/kg with MEL 100 mg/kg, and Crea concentration was also higher when birds were fed CYA at 50 mg/kg. No crystals were found in kidneys but dilated renal tubules and small blood vessel expansion were found in kidneys of birds fed CYA at 50 mg/kg and CYA at 33.3 mg/kg with MEL 100 mg/kg. The apoptosis rate (AR) of kidneys of all birds fed CYA and MEL contaminated diets were higher than the control group. These results indicated that the dietary addition of CYA and MEL could induce kidney damage, and the effects were harmful when the ratio of CYA/MEL was 1:3.