Effects of short-chain fructooligosaccharides on growth performance and hepatic intermediary metabolism in turbot (Scophthalmus maximus) reared at winter and summer temperatures

Abstract

The effect of short-chain fructooligosaccharides (scFOS) incorporation on growth, feed utilization, body composition, plasmatic metabolites and selected liver enzyme activities of turbot juveniles reared at winter (15 °C) and summer (20 °C) temperatures was studied. Four comparable diets were formulated to contain circa 50 : 50 fish meal and plant ingredients as protein sources. Experimental diets included increasing levels of scFOS (0, 5, 10 and 20 g kg−1). Final weight was higher at 20 °C, but thermal growth unit, feed efficiency, nitrogen and energy retention were better at 15 °C. scFOS supplementation did not affect fish growth performance. Fish reared at 15 °C had higher liver glycogen, visceral and hepatosomatic indices. Liver lipids, plasma triglycerides, total lipids, cholesterol HDL and LDL were higher in turbot reared at 20 °C. Malic enzyme, fatty acid synthetase, alanine aminotransferase and glutamate dehydrogenase activities were higher in fish reared at 15 °C. Malic enzyme was lower in turbot fed with 20 g kg−1 scFOS compared to control diet; however, fatty acid synthetase presented an increasing trend as dietary scFOS increased up to 10 g kg−1. Glutamate dehydrogenase activity was higher in fish fed the control diet. Results seem to indicate no benefits of scFOS incorporation to diets on growth performance of turbot.