Optimizing Turbot Growth and Body Quality Through Bile Acids
Under two dietary fat levels of 10% and 18%, four isonitrogenous diets were formulated by supplementing 0% or 1.5% bile acids respectively. These diets were fed to juvenile turbot (Scophthalmus maximus) with an initial average body weight of (45.78±0.11)g for 8 weeks to investigate the effects of bile acids supplementation on growth performance, body composition and lipid metabolism of juvenile turbot under different dietary fat levels.
The results showed that:
Both increased dietary fat level and bile acid supplementation significantly improved weight gain rate, specific growth rate and protein efficiency ratio, while reducing feed conversion ratio in juvenile turbot (P<0.05). At the same fat level, bile acids supplementation significantly enhanced the growth of experimental fish and reduced hepatosomatic index (P<0.05).
With the increase of dietary fat level, the crude fat content in tissues showed an upward trend; while bile acids supplementation reduced fat accumulation in tissues. However, the moisture and crude protein content in whole fish and muscle were mainly affected by dietary bile acid level (P<0.05).
Bile acids significantly decreased the polyunsaturated fatty acid content (P<0.05) and increased saturated fatty acid and monounsaturated fatty acid content in muscle of juvenile turbot (P<0.05).
Dietary bile acids supplementation reduced serum triglyceride, total cholesterol, HDL-cholesterol, LDL-cholesterol contents as well as aspartate aminotransferase and alanine aminotransferase activities in experimental fish (P<0.05), while dietary fat level showed opposite effects on these blood biochemical parameters.
Both increased dietary fat level and bile acids supplementation enhanced hepatic lipoprotein lipase, hepatic lipase, total lipase and intestinal lipase activities in experimental fish (P<0.05). Moreover, significant interactive effects between bile acids and fat levels on lipid metabolism were observed (P<0.05).
In conclusion, bile acids supplementation at both fat levels promoted the growth of juvenile turbot, improved feed utilization, enhanced lipid digestion and absorption, and reduced crude fat content in tissues.
