Influence of dietary fat sources on growth, bacterial resistance, and antioxidant ability of liver in common carp, Cyprinus carpio

The current study was conducted to determine the effect of dietary fat sources on fish growth, resistance, and antioxidant ability in common carp. The experimental diets were based on various fat sources, including fish oil (FO), linseed oil (LO), sesame oil (SO), and a mixture of LO and SO (SLO). The common carp (23.8±0.7 g) were distributed into a 100 L-tank system at a density of 25 fish per tank. Fish were fed experimental feed to satiation for seven weeks, and the consumable feed amount was recorded daily. After a 7-week trial, fish were infected with Aeromonas veronii at a dose of 0.43×10^6 CFU/mL and monitored for 14 days. The fish mortality was checked daily. Fish livers were sampled after feeding and on the second day post-bacterial injection to analyze the antioxidant parameters. The results indicated that the fat sources did not affect the fish growth, feed conversion rate, survival, and cumulative mortality in the challenge test but modified the antioxidant ability in fish liver. The malondialdehyde activity in SLO-fed fish was lower than that in FO group at the end of the feeding trial, while the glutathione activity in SO-fed fish was higher than those in other plant oil-fed fish after the bacterial challenge. The highest values of superoxide dismutase activity were recorded in LO fish after the nutritional trial and FO ones after the challenge test.