Modulation of key metabolic enzyme of Labeo rohita (Hamilton) juvenile: effect of dietary starch type, protein level and exogenous alpha-amylase in the diet.
ABSTRACT A 60-day feeding trial was conducted to delineate the effect of both gelatinized (G) and non-gelatinized (NG) corn with or without supplementation of exogenous alpha-amylase, either at optimum (35%) or sub-optimum (27%) protein levels, on blood glucose, and the key metabolic enzymes of glycolysis (hexokinase, HK), gluconeogenesis (glucose-6 phosphatase, G6Pase and fructose-1,6 bisphosphatase, FBPase), lipogenesis (glucose-6 phosphate dehydrogenase, G6PD) and amino acid metabolism (alanine amino transferase, ALT and aspartate amino transferase, AST) in Labeo rohita. Three hundred and sixty juveniles (average weight 10 +/- 0.15 g) were randomly distributed into 12 treatment groups with each of two replicates. Twelve semi-purified diets containing either 35 or 27% crude protein were prepared by including G or NG corn as carbohydrate source with different levels of microbial alpha-amylase (0, 50, 100 and 150 mg kg(-1)). The G corn fed groups showed significantly higher (P < 0.05) blood glucose and G6PD activity, whereas G6Pase, FBPase, ALT and AST activity in liver was higher in the NG corn fed group. Dietary corn type, alpha-amylase level in diet or their interaction had no significant effect (P > 0.05) on liver HK activity, but the optimum crude protein (35%) fed group showed higher HK activity than their low protein counterparts. The sub-optimum crude protein (27%) fed group showed significantly higher (P < 0.05) G6PD activity than the optimum protein fed group, whereas the reverse trend was observed for HK, G6Pase, FBPase, ALT and AST activity. Addition of 50 mg alpha-amylase kg(-1) feed showed increased blood glucose and G6PD activity of the NG corn fed group, whereas the reverse trend was found for G6Pase, FBPase, ALT and AST activity in liver, which was similar to that of the G or NG corn supplemented with 100/150 mg alpha-amylase kg(-1) feed. Data on enzyme activities suggest that NG corn in the diet significantly induced more gluconeogenic and amino acid metabolic enzyme activity, whereas G corn induced increased lipogenic enzyme activity. Increased amino acid catabolic enzyme (ALT and AST) activity was observed either at optimum protein (35%) irrespective of corn type or NG corn without supplementation of alpha-amylase irrespective of protein level in the diet.
- SourceAvailable from: nutrition.orgJournal of Nutrition 05/1968; 94(4):463-8. · 4.20 Impact Factor
- [show abstract] [hide abstract]
ABSTRACT: Rainbow trout were fed for 10 weeks with either a carbohydrate-free diet (C-free) or with four experimental diets containing various levels (20 or 40%) and sources of starch (extruded wheat or peas) in order to examine metabolic utilisation of dietary vegetable carbohydrates and its endocrine control. The study was focused on the parameters described as limiting in glucose metabolism in fish. Feeding trials were conducted at 8 and 18 degrees C to establish whether carbohydrate-rich diets can be used in trout farming irrespective of water temperature. At both temperatures, pea diets (especially the highest level) resulted in a feed efficiency as high as the C-free diet. Fish had similar growth rates except when fed the low wheat content diet. Glycaemia values 6 h after feeding were significantly higher in trout fed carbohydrate diets than those given the C-free diet, whereas plasma insulin levels were similar independently of the levels of dietary starch. This study provides the first evidence that glucokinase (GK) activity and mRNA level in trout liver increase in proportion to the content of dietary starch. Nevertheless, these changes were not correlated with plasma insulin levels. Insulin-like growth factor-I (IGF-I) binding and number of receptors in skeletal muscle were consistently higher than those for insulin but no diet-induced differences were found for any of these parameters. Temperature clearly affected the postprandial profile of glucose and insulin, which both showed lower levels 6 h after feeding at 8 degrees C than at 18 degrees C, which was consistent with a lower feed intake. Glucose and insulin levels decreased markedly 24 h after feeding at 18 degrees C, while they were still high at 8 degrees C, an observation concordant with delayed transit rate. These findings indicate satisfactory adaptation of rainbow trout to diets with a relatively high vegetable starch content, especially when provided as extruded peas, and indicate that diets with increased levels of carbohydrates can be used in this species even when it is reared at low temperature.Regulatory Peptides 02/2003; 110(2):123-32. · 2.06 Impact Factor
- [show abstract] [hide abstract]
ABSTRACT: Purified diets containing equivalent amounts of glucose, maltose, fructose, sucrose, corn starch and dextrin were fed to fingerling channel catfish (Icatalurus punctatus) to compare the growth responses to these various carbohydrates. The best growth response was achieved with dextrin and the next best with corn starch. Fish grew at the same rate when glucose, maltose or sucrose was the only dietary carbohydrate source. Dietary fructose resulted in the lowest growth rate. Feed efficiency and percent retained energy values followed the same pattern as growth rates. These data suggest that the catfish is apparently unable to utilize dietary mono- and disaccharides as energy sources. Oral carbohydrate tolerance tests using glucose, maltose, fructose, sucrose and dextrin were conducted with larger channel catfish. Oral glucose and maltose resulted in a persistent hyperglycemia indicative of a diabetic-like status. Fructose appeared to be poorly absorbed from the intestinal tract and did not appear to be converted to glucose. Oral administration of sucrose was followed by a gradual increase in plasma glucose, with no detectable fructose being absorbed until the 6-h period. Oral dextrin resulted in less than a two-fold increase in plasma glucose, which remained constant from 2 to 4 h after administration and then declined. These observations are consistent with the hypothesis that certain fishes, including the channel catfish, resemble diabetic animals by having insufficient insulin for maximum carbohydrate utilization.Journal of Nutrition 03/1987; 117(2):280-5. · 4.20 Impact Factor