Energy metabolism and protein balance in growing rats fed different levels of dietary fibre and protein

High dietary non-starch polysaccharides detrimental to nutrient digestibility, digestive enzyme activity, growth performance, and intestinal morphology in largemouth bass, Micropterus salmoides

An 8-weeks feeding trial was carried out to evaluate the effects of different levels of dietary non-starch polysaccharide on the growth, apparent nutrient digestibility, intestinal development, and morphology of largemouth bass (Micropterus salmoides). Seven isoproteic and isolipidic experimental diets were formulated (crude protein 47.00%, crude lipid 12.50%), containing 0, 3, 6, 9, 12, 15, and 18% non-starch polysaccharides (NSPs) (named Control, NSPs3, NSPs6, NSPs9, NSPs12, NSPs15, and NSPs18), respectively. Dietary inclusion of NSPs below 9% showed no negative impacts on fish growth and feed utilization efficiency, whereas dietary NSPs inclusion level above 9% decreased weight gain rate, specific growth rate, protein efficiency, protein deposition rate, apparent digestibility of dry matter and protein, and were accompanied by a reduction in intestinal protease, Na+/K+-ATPase and alkaline phosphatase activity and an increase in feed intake and feed coefficient. The activity of lipase was significantly decreased when dietary inclusion of 15 and 18% NSPs. Moreover, the lipid deposition rate and the apparent digestibility of lipids were significantly decreased since dietary inclusion of 9% NSPs. Dietary inclusion of NSPs above 12% significantly up-regulated intestinal GLP-2 gene’s expression, and was accompanied by significant changes in hindgut morphology, including increases in villus length and width, muscularis thickness and number of goblet cell, as well as a decrease in crypt depth. Additionally, dietary inclusion of NSPs above 3% significantly increased intestinal length index, and the viserosomatic index was significantly increased when dietary NSPs exceeded 15%. The linear regression analysis based on weight gain rate and feed coefficient showed that the appropriate dietary NSPs level of juvenile largemouth bass should not above 5.51%. In conclusion, high dietary NSPs adversely affects digestive enzyme activity and intestinal morphology, which in turn reduced the apparent digestibility of dietary nutrients and growth of juvenile largemouth bass.

Effect of dietary oxidized konjac glucomannan on Schizothorax prenanti growth performance, body composition, intestinal morphology and intestinal microflora

The aim of the present study was to examine the effect of oxidized konjac glucomannan (OKGM) on Schizothorax prenanti growth performance, body composition, intestinal morphology and intestinal microflora. Fish were fed a basal diet or basal diet plus 4.0, 8.0, 16.0 and 32.0 g kg(-1) OKGM for 60 days. The results indicated that WGR and SGR were significantly higher in fish fed 8.0 and 16.0 g kg(-1) OKGM diets (P < 0.05) than those in fish fed basal diet, and PER was significantly higher and FCR was significantly lower in fish fed 16.0 g kg(-1) OKGM diet (P < 0.05). The content of body protein, lipid and moisture was affected by the OKGM diets. The light and electron microscopy demonstrated that intestinal morphology of fish fed 8.0 and 16.0 g kg(-1) OKGM diet was better (P < 0.05) than the control group, including mucosa fold height, mucosal epithelial height, submucosa height, longitudinal muscularis thickness and circular muscularis thickness. Compared with the control group, fish fed 32.0 g kg(-1) OKGM diet showed significantly lower goblet cell number in anterior intestine (P < 0.05). Furthermore, intestinal microflora was analyzed by PCR-DGGE, and the results showed that OKGM diets also significantly modulated the intestinal microflora of fish (P < 0.05). The study clearly demonstrates that OKGM could enhance the growth performance, improve intestinal morphology and modulate intestinal microflora of S. prenanti, and the optimal dietary OKGM levels was suggested to be 16.0 g kg(-1).