Growth performance and health of hybrid catfish (Clarias macrocephalus x Clarias gariepinus) fed with supplemental melamine and urea formaldehyde diets

Abstract

An experiment was conducted to investigate the effects of three graded levels (0.5, 1.0 and 2.0%) of melamine (Me) and urea formaldehyde (UF) in hybrid catfish. The treatment diets were conducted with one control (no addition) in a completely randomized design. Three hundred and thirty six hybrid catfish with the initial weight of 9.70 g were assigned to 7 dietary treatments and fed for 8 weeks. Significant difference (P<0.05) in growth performance and feed efficiency between the control and the fish fed with Me and UF were observed. The growth performance of the fish fed with 1.0% and 2.0% Me and UF in diets were significantly lower than that of the control while at the level of 2.0% in diets, the feed efficiency was significantly less (P<0.05). The survival rate (SR) and the economic loss index (ELI) as determined by the production index (PI) showed no significant decrease (P>0.05) although the values were found to have decreased with the increase of both Me and UF in diets. Abnormality of skin coloration when compared to the control was observed within 2 weeks: darker color in some fish fed with Me diets while colorlessness were observed in fish fed with UF diets. The lesion and degeneration of liver, kidney and spleen were found to have diffused hemorrhage, enlargement, abnormal shape, and obvious coloration change. Microscopic examinations of wet mount tissue and of histological changes of those tissue organs found them to be degenerated and damaged with numerous dark brown or transparent crystals, or some light green crystals. Blood parameters (BUN, uric acid and creatinine) showed significant abnormality (P<0.05) from the control. These results provided evidence of correlation between the amounts and the sizes of crystals, the degrees of damage, and the levels of Me and UF in diets. The degeneration of tissue organs and crystals provided strong evidence in the prediction of Me and UF contamination in diets, and of their toxicity in hybrid catfish.