Effect Of Cyanuric Acid With And Without Melamine On Broiler Performance, Health And Residues In Tissues

The purpose of this study was to evaluate the effect of cyanuric acid (CYA) and a combination of melamine (MEL) and CYA on performance, hepatic and renal health and residues in plasma and tissues (muscle, liver and kidney) in broilers. A total of 1200 COBB 500 male broilers were randomly allocated into 1 of 10 treatments by a 5×2 factorial design in a 42-day experiment. The dietary treatments were as follows:T1 to T5:basal diets with addition of CYA at 0,10,20,33.3,50 mg per kg diet; T6 to T10:basal diet with CYA regimens similar to T1 to T5 but with addition of MEL at 100 mg per kg diet. There were 6 replication pens with 20 chicks per pen. A 7-day metabolic experiment was conducted after growth experiment. Average daily feed intake (ADFI), body weight (BW), body weight gain (BWG) and feed to gain ratio (F/G) were measured and calculated on day 22 and day 43. The concentration of grossenergy (GE), crude protein (CP), Ca and P in feed and fecal sample were measured and the utilization rates were calculated. Serum was collected on day 22 and day 43, and plasma was collected on day 43. The acticity of glutamic pyruvic transaminase (GPT) and glutamic oxalacetic transaminase (GOT) and the concentration of uric acid (UA) and creaine (CRE) in serum were measured. Tissues from livers and kidneys were fixed for histopathologic findings and sections from kidneys were determined the apotosis rate (AR). CYA and MEL residues in plasma and tissues such as muscles, livers and kidneys were determined by LC-MS/MS.No significant differences were found on BW, BWG, ADFI, F/G and digestibility of CP, Ca and P (P>0.05). But the BW on 21 d, and the BWG and ADFI among 1～21d tended to decrease with the increase of CYA supplementation levels (P>0.05). Utilization of GE was lower when birds fed CYA at 50mg/kg (P<0.05). No differences were observed in the serum activity of GPT and GOT (P>0.05). But on d 21, the concentration of UA and CRE were significantly greater when birds were fed CYA at 33.3mg/kg with MEL 100 mg/kg (P<0.05), and the concentration of CRE was also higher when birds were fed CYA at 50mg/kg (P<0.05). Besides, the interaction of CYA and MEL were significantly influence the concentration of CRE (P<0.05). 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 AR of kidneys of all birds fed CYA and MEL contaminated diets were all higher than the control group (P<0.05). These results indicated that a dietary level of≥50 mg of CYA/kg of feed or 33.3 mg of CYA with 100 mg of MEL/kg of feed could induce renal damage. The residue of CYA in plasma and kidney could be detected when CYA added alone or added with MEL, and the highest level was found at the addition of CYA at 33.3 or 50 mg/kg. When CYA was added alone, the residue of MEL in breast muscle, liver, and kidney could be detected.Moreover, the residue of MEL in liver and kidney could increase significantly with the addition of CYA and MEL together.These results indicated that the dietary addition of CYA 10-50 mg/kg could do harm to the performance and the health of broilers. The harmful effect was greatest when CYA/MEL was 1/3. Residues of CYA or MEL in broiler tissues could be detected when birds were fed diets contaminated by CYA or MEL, and CYA and MEL added together could increase the MEL residues in tissues with the highest residue level in kendey at CYA/MEL 1/3 while in lever at CYA/MEL 1/5.