|Rawles, Steven - Steve|
Submitted to: Feed Management
Publication Type: Trade journal
Publication Acceptance Date: 12/1/1999
Publication Date: N/A
Citation: RAWLES, S.D., GATLIN, D.M. ADVANCES IN HYBRID STRIPED BASS NUTRITION.. FEED MANAGEMENT. 2000. p.19-21. Interpretive Summary:
Technical Abstract: One strategy fish farmers use to keep a competitive edge is reducing feed costs. Over 40% of the variable cost of hybrid striped bass farming is feed. Quantitative requirements of these fish for many diet constituents were determined in our lab. Data on the known requirements of hybrid striped bass are presented in table form. We also studied intermediary metabolism of carbohydrates (CHO). Comparison between sunshine and striped bass fed diets containing glucose, maltose, or dextrin showed superior growth of sunshine bass irrespective of CHO level. Increasing CHO from 0% to 25% of diet increased weight gain, feed efficiency, hepatosomatic index (HSI) and intraperitoneal fat (IPF). Increases in HSI correlated with increases in liver glycogen. Effects of CHO complexity varied but both taxa were able to use 25% carbohydrate. Digestible energy of dextrin (1.73 kcal/g) for sunshine bass was not as high as that of glucose (2.74 kcal/g) or maltose (2.38 kcal/g). Increasing carbohydrate from 20% to 40% of diet decreased weight gain 25%, feed efficiency 15%, and protein efficiency 11%. Muscle ratio decreased but liver lipid and glycogen and IPF increased in fish fed diets with glucose compared to fish fed diets with maltose or dextrin. Liver glycogen and lipid approached 50-60% (dry-weight). Energy storage increased with lipid, not carbohydrate, level of the diet. Glycemic response indicates much dietary carbohydrate may be lost to excretion. In vitro lipogenesis and glycolysis indicate glucose was not an important precursor for de novo lipogenesis. Diet carbohydrate may provide energy for triacylglyceride biosynthesis and glycerol-glyceride for fatty acid esterification. The digestibility of energy and nutrients in common feed ingredients after steam extrusion are also presented and discussed.