The Thai Journal of Veterinary Medicine


A study was conducted to determine the effects of dietary graded levels of melamine, urea-formaldehyde (UF) and their mixture on growth performance, carcass quality, melamine residues and microscopic changes in broiler tissues from d-1 to d-42 followed by a 7-d feeding of withdrawal diets. One thousand and forty 1-d-old equal mixed-sex Arber Acres broiler were assigned to 13 dietary treatments with 4 replicate pens of 20 chicks assigned to each treatment. The diets of melamine, UF and their mixture contained four graded levels (0.25, 0.50, 0.75 and 1.00%) but no melamine or UF was added to the control diet. There was no difference (p>0.05) in feed intake (FI) among controls and chickens fed on the three products (melamine or UF or their mixture). Body weight gain (BWG) decreased significantly (p<0.05) in birds fed > 0.75% melamine, with the greatest decrease in BWG observed in birds fed 1.00% melamine. There was a difference (p<0.05) in BWG between the basal diet and chickens fed on the three products. BWG decreased linearly (p<0.05) with increasing levels of dietary melamine. Chickens that are fed on the three products were less efficient (p<0.05) in converting feed to gain compared with the controls. Survival percentage decreased (p<0.05) in chickens fed all four levels of melamine or fed > 0.50% UF or fed 1.00% or a mixture of both compared with the controls. Birds fed with melamine showed a decreased (p<0.05) survival percentage compared with chicks fed UF or a mixture of both. These findings demonstrate that UF has a higher toleration level than melamine. Chickens Fed the four levels of melamine showed a lower (p<0.05) European production efficiency factor (EPEF) compared with birds fed UF, the mixture or the controls. The influence of melamine, UF or their mixture showed both linear (p<0.05) and quadratic (p<0.05) economic lost effects as the level of either melamine, UF or their mixture in the diet increased. There was no difference in carcass dressing percentage and total carcass yield among treatments. Residue levels of melamine in meat and liver tissues were below the detection limit when the diet contained less than 0.50% melamine supplementation in the diets. Tissue melamine levels increased (p<0.05) in both meat and liver tissues with the increasing levels of melamine in the diets. The melamine residues in the liver were higher (p<0.05) than in the breast tissues. A withdrawal period of 7-d was found to clear the tissues of melamine, which means that chickens had an ability to quickly deplete the melamine that accumulated in their tissues. Microscopic examination of the melamine crystal on liver, kidney and spleen tissues provided evidence of a strong correlation between the amount and size of golden brown crystals and diets containing melamine concentration which are useful in the prediction of dietary melamine dosage in the diets.



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