The influence of different dietary oil qualities on growth rate, feed utilization and oxidative stress in Atlantic cod
The aim of our study was to investigate the effects of dietary oils, with different degrees of oxidative stability, on growth performance, lipid and fatty acid (FA) composition, oxidative stress status and health parameters of Atlantic cod. The dietary oils were a traditional fish oil (FO), a FO and rapeseed oil blend (FO-RO, 1:1), or two salmon oil (SO) qualities with low (SO-L) or high (SO-H) level of oxidation products. Fish (479 g) were fed one of the four diets for 112 days (800 g). No significant differences in growth rate, feed efficiency or morphology of the intestine were found. However, there was a tendency to higher thiobarbituric acid reactive substance values in plasma and liver in the FO and SO groups than in the FO-RO group, although only significant for the FO group in plasma. There was also a tendency to reduced activities of catalase and SOD in the FO and SO groups. An increase in transcripts related to oxidative stress in the liver and heart was obvious. The FA composition of liver reflected the FA composition of the diet, with lowest n-3 FA percentage in the FO-RO group, intermediate percentage in the SO groups and highest percentage in the FO group.