EFFECT OF OXIDIZED OILS ON GROWTH, BODY COLOR AND ANTIOXIDANT CAPACITY OF CHANNEL CATFISH, ICTALURUS PUNCTATUS

Oils are widely used in aquatic feed to supply essential fatty acids and energy for the fish. However, the abundance of unsaturated fatty acids makes oils susceptible to be oxidized, resulting in harmful effect on the health of fish. To investigate the effect of dietary oxidized oils on the growth performance, body color and antioxidant capacity in liver of channel catfish, Ictalurus punctatus, six isonitrogenous and isolipidic diets were prepared to feed channel catfish (150.5±4.2) g. The six diets were designed with 6% supplementation level of fish oil (FO-6), soybean oil (SO-6), mixed oil (3% fish oil + 3% soybean oil, MO-6), oxidized fish oil (OFO-6), oxidized soybean oil (OSO-6), oxidized mixed oil (3% oxidized fish oil + 3% oxidized soybean oil, OMO-6), respectively. After 8 weeks feeding, the fish fed FO-6, SO-6 or MO-6 diet showed no differences in weight gain (WG), feed conversion ratio (FCR), muscle composition, body color and antioxidant indicators in liver (P>0.05), which indicated that soybean oil could completely substitute the inclusion of fish oil in the diet of channel catfish. The WG and muscle lipid level of the three oxidized oil groups were significantly lower, andFCR, skin yellowness, liver malondialdehyde content, and total bilirubin, direct bilirubin, alanine aminotransferase, aspartate aminotransferase in serum were significantly higher (P<0.05) than that of the normal oil groups. The activities of catalase and superoxide dismutase, and the glutathione contents in liver were reduced by dietary oxidized oils (P<0.05), but the dorsal muscle color and moisture, crude protein, ash content in flesh were not affected (P>0.05). The above results showed that 6% oxidized oils (fish oil, soybean oil, or mixed oil) reduced the growth performance, increased the yellowness of skin and damaged the antioxidant capacity of liver of channel catfish. Soybean oil could completely replace the fish oil inclusion in the diet of channel catfish.