|Lochmann, Rebecca - UAPB|
Submitted to: Book of Abstracts Aquaculture America
Publication Type: Abstract Only
Publication Acceptance Date: December 3, 2004
Publication Date: January 16, 2005
Citation: Rawles, S.D., Gaylord, T.G., Lochmann, R. 2005. Heptic glucose oxidation and lipogenesis in sunshine bass fed diets with different amylose to amylopectin ratios [abstract]. Book of Abstracts, Aquaculture America. p. 357. Technical Abstract: Increasing the ratio of amylose to amylopectin starch in the diet improves carbohydrate utilization in some mammals. This strategy may be applicable to fish production. A 7-week feeding trial with fingerling (160 g) sunshine bass Morone chrysops x M. saxatilis was conducted using purified diets with different amylose:amylopectin ratios. At the conclusion of the feeding trial, liver slices from 5-6 fish per dietary treatment were incubated with radioactive substrates for the determination of glucose utilization and de novo lipid and triacylglycerol biosynthesis. Liver CO2 and glycogen production were significantly reduced in fish fed the diet containing the highest amount of amylose (30PEC). Hepatic glycogen production tended to decrease with increasing amylose in the diet. The rate of [14C]glucose oxidation to CO2 in the liver comprised 88 to 96% of the total glucose utilization and was lowest in fish fed the diets containing glucose (GLC) or high-amylose ratio. Rates of both esterification (from labeled palmitate) and glyceride formation (from glucose) appeared lowest in fish fed diets containing glucose or the highest amount of amylose (30PEC). Rates of glyceride formation were 1.5 to 2 times higher than rates of esterification in fish fed diets of high amylopectin ratio when compared to the same rates in fish fed diets containing glucose or a high percentage of amylose. Differences in liver utilization are most likely due to differential digestion, excretion, and the timing of glucose availability at the cellular level. In conclusion, high-amylose diets had minimal positive effects on hybrid striped bass carbohydrate use.