The effects of dietary cadmium on growth, antioxidant defence system and feed evaluation performance of rainbow trout (Oncorhynchus mykiss)

Abstract

The present study was carried out to determine the effect of dietary cadmium exposure on growth performance, changes in manganese, zinc, copper, calcium, magnesium, iron, selenium, and cadmium metals in liver and muscle tissue, liver antioxidant enzymes, and the histology of the fish. Rainbow trout (Oncorhynchus mykiss) with weights of 39.45 ±1.13 g was used in the experiment conducted in 2 groups and three replicates. The Control group was fed a cadmium-free diet, and the Cadmium group was fed a diet containing 5.03 µg/kg of cadmium twice a day until satiation. It was determined that cadmium intake through the diet affected growth rate and the feed evaluation performance negatively. In fish exposed to cadmium, manganese, zinc, copper, calcium, magnesium, iron, selenium, superoxide dismutase, catalase and glutathione peroxidase values in both muscle and liver tissues were significantly (p<0.05) decreased, whereas cadmium levels in muscle and liver and malondialdehyde levels in liver were significantly (p<0.05) increased. The histopathological examination of the liver revealed that cadmium caused liver damage. These results showed that rainbow trout exposed to dietary cadmium were highly sensitive to the metal, and the decreased levels of metals such as copper, zinc, manganese, and selenium in the liver tissue, which are involved in the antioxidant defence system, can be considered an indicator of the weakening of the antioxidant defence system.