Pathophysiological changes associated with dietary melamine and cyanuric acid toxicity in red tilapia

Abstract

This study examined the adverse effects of feed-delivered melamine (MEL) and cyanuric acid (CYA) in red tilapia. Diet 1 (without MEL and CYA), diets 2-4 (with MEL and CYA at 2.5, 5 and 7.5 g kg(-1) diet, respectively) and diets 5 and 6 (with either MEL or CYA at 10 g kg(-1) diet) were examined. MEL alone lowered both growth and FCR (P < 0.05), and CYA alone reduced the FCR of tilapia. Protein efficiency ratio and apparent net utilization of fish on diets 2-6 were poor (P < 0.05). The renal tubules of fish ingested MEL-CYA combination had melamine-cyanurate crystals. On the other hand, diets with only one chemical did not induce such crystals. MEL and CYA in whole body, fillet or viscera reflected their dietary inclusion levels. The levels of Hsp70 were increased in the liver of fish that ingested MEL and CYA, in combination or singly (P < 0.05). However, in the kidney, such an increase was visible only in the fish that received diet 4 (P < 0.05). Combination of MEL and CYA at inclusion levels > 5 g kg(-1) diet induced the activity of catalase in liver and the activity of glutathione peroxidase in liver and kidneys. Therefore, these adulterants should not be included in fish feeds.

A study on growth, histopathology and oxidative stress in Asian sea bass on diets with various loadings of melamine and cyanuric acid adulterants

“…In our previous study, Phromkunthong et al (2014) pointed out that the SGR of red tilapia was lower in fish that received MEL alone in the diet relative to control, whereas no significant effects were noted with combined MEL-CYA in the diet. Similarly, in the present study, the SGR of Asian sea bass receiving MEL alone was significantly lower than the control, suggesting that these fish are more sensitive to MEL than mammals,.…”

“…For sea bass even a 2.5 g/kg diet supplementation of MEL and CYA each in the diet, here equivalent to the average daily intake of 77 mg/kg BW per day, reduced the growth rate of sea bass. In comparison, tilapia was less sensitive to these contaminants, as its growth was not significantly affected by MEL and CYA combinations of 2.5-7.5 g/kg feed each (Phromkunthong et al, 2014). Further, results from the present study clearly demonstrate that the incorporation of high doses of MEL-CYA from 7.5:7.5 to 10:10 g/kg diet (equivalent average daily intakes of 212 to 293 mg/kg BW per day, respectively) negatively influenced FCR.…”

“…These feeds were sent to France, Germany and the United Kingdom, and had melamine concentrations in the range 1.6-410 mg/kg (European Commission, 2008;INFOSAN, 2008). MEL was not the only adulterant in these cases, another toxic compound, CYA, was also detected (Phromkunthong et al, 2014). Therefore, WHO (2008) recommended a tolerated daily intake (TDI) of 0.2 mg/kg body weight for MEL and 1.5 mg/kg body weight for CYA for humans.…”

“…Several studies of renal failure reported in pets and farm animals, including aquatic species and ruminants that received MEL and CYA at high dosages, found crystals in the kidneys, similar to the pathological signs of renal failure (Brown et al, 2007;Nilubol et al, 2009;Puschner et al, 2007;Reimschuessel et al, 2008;Sun et al, 2010;Thompson et al, 2008). To understand the effects of MEL and its derivative (CYA) more clearly, Phromkunthong et al (2014) studied the effects of MEL or CYA and MEL-CYA combination on tilapia, through histopathological observations and using stress biomarkers. They also found that the combination of MEL and CYA induces crystal nephropathy.…”

Melamine–cyanurate complexes and oxidative stress markers in trout kidney following melamine and cyanuric acid long-term co-exposure and withdrawal

“…Triazines may produce a greater hydrogen peroxide concentration leading to oxidative stress in exposed tissues. Increased levels of CAT can be a prompt signal against the enhanced production of free radicals induced by MEL-CYA diets Phromkunthong et al (2014).…”