| 论文摘要： |
To investigate the effects of niacin on growth, digestion and absorption capacity, and the potential mechanism for digestive and brush border enzyme activities, grass carp (Ctenopharyngodon idella) (256 +/- 0.41g) were fed diets containing 3.95 (basal diet group), 14.92, 24.98, 35.03, 44.97 and 55.01mgniacinkg(-1) diet for 8weeks. Results indicated that percentage weight gain (PWG), feed intake and feed efficiency were the lowest in basal group (P<0.05). Similarly, niacin deficiency decreased hepatopancreas trypsin, chymotrypsin, lipase and amylase activities (P<0.05), intestinal Na+, K+-ATPase, alkaline phosphatase, -glutamyl transpeptidase and creatine kinase (CK) activities, the cholecystokinin (CCK) content in proximal intestine (PI) and growth hormone content in serum (P<0.05). Furthermore, niacin deficiency downregulated gene expression of hepatopancreas trypsinogen 1, trypsinogen 2, chymotrypsinogen and amylase, intestinal Na+, K+-ATPase alpha subunit isoform 1, Na+, K+-ATPase alpha subunit isoform 8 and CK, and target of rapamycin (TOR) and S6 kinase 1 (S6K1) of hepatopancreas and intestine (P<0.05), whereas upregulated eIF4E-binding protein (4EBP) gene expression (P<0.05). The niacinrequirement for young grass carp (256-689g) based on PWG, hepatopancreas trypsin activity and Na+, K+-ATPase in PI was 34.01, 35.10 and 42.08mgkg(-1) diet, respectively. |
