Aquaculture Nutrition, Early View (Online Version of Record published before inclusion in an issue)
To study the effect of propolis in crude form (CPP), prepared without any chemical refinement (CPP) on Dicentrarchus labrax under low-temperature stress, sea bass juveniles were randomly divided into three groups: a control group fed with basal diet and two treatment groups fed with basal diet supplemented with 1.25 and 2.5 g kg−1 of propolis.
At the end of a 10-week feeding trial, sea bass were exposed to low-temperature stress at 12 °C for 24 h. The growth performance, RNA/DNA ratio and changes in serum biochemical parameters were investigated. Dietary intake of propolis stimulated the specific growth rate (SGR), feed conversion efficiency (FCE), RNA/DNA ratio and alkaline phosphatase (ALP) enzyme activity, while decreasing plasma triglycerides and aspartate aminotransferase (AST) activity. Supplement of 2.5 g kg−1 CPP in diet significantly increased the mean SGR and FCE up to 9% and 13.4%, respectively, in comparison with the control group. Low-temperature stress elevated serum triglycerides, glucose and cortisol levels in all groups; however, glucose and cortisol reached significantly lower end values in group receiving highest amount of propolis in diet.
This study suggests that ingestion of basal diet supplemented with 2.5 g kg−1 of propolis could prevent adverse effects of low-temperature stress and promote the growth of sea bass.