Effects Of Glutamine,Glutamine Dipeptide On Growth,Physiological And Biochemical Indexes Of Juvenile Ctenopharyngodon Idellus

An 8-week feeding experiment was conducted to evaluate the effect of glutamine and glutamine dipeptide on growth, blood physiological, biochemical indexes and intestinal morphology of juvenile grass carp (initial average weight,7.16+0.1 g].Experiment 1:The grass carp were randomly allocated into 5 groups with 3 replicates of 50 fish. Five practical diets were formulated to supply 0.00%,0.30%,0.60%,0.90%,1.20% glutamine to the basal diet of grass carp, respectively. Each diet was randomly fed to triplicate groups of 50 fish per net cage (1.5×1.5× 1.5). The feeding trial lasted for 56 days. The results showed that:The final weight, weight gain rate (WGR) and specific growth rate (SGR) were significantly improved with the increasing levels of glutamine supplementation. No significant difference was observed among groups with glutamine supplementation (P> 0.05); Feed coefficient ratio (FCR) decreased firstly and then decreased with the increasing glutamine levels (P< 0.05); Glutamine supplementation had no significant effect on coefficient of fatness (CF), liver body weight ratio and the organ body ratio, however significantly affected the digestive enzyme activities. The activities of lipase and trypsase increased with the increase of glutamine. The lowest amylase activity was observed when fish were fed diet with 0.3% glutamine (P<0.05). No significant differences on moisture and crude lipid were found, but the crude protein and ash of juvenile grass carp decreased firstly and then increased (P<0.05) with the increase of glutamine. Blood glucose (GLU) content, the activities of glutamic-oxalacetic transaminase (GOT), glutamic-pyruvic transaminase (GPT) activity were significantly improved with the increasing levels of glutamine. The content of triglycerides(TG) and cholesterol(CHO) and the activities of superoxide dismutase (SOD), C3, C4 and lysozyme (LZM) in serum of juvenile grass carp(P < 0.05)were significantly decreased. Fish fed diet with 0.30% glutamine showed a significantly higher urea nitrogen (BUN) levels (P<0.05) when compared to that in the control group. The diets with glutamine supplementation had a significantly increased activities of glutathione peroxidase (GSH-Px) and malonaldehyde (MDA) content (P<0.05). The levels of secreted immunoglobulin(A) (S-LgA) significantly decreased (P<0.05) in fish fed the diet with levels of glutamine of 0.6%, but no significant differences on IgM and hydrocortisone. Glutamine had no significantly effects on foregut villus height and the recessed depth of juvenile Grass Carp(P>0.05),but significantly affects the thickness of the intestinal mucosa, goblet cells, lymphocytes. Add the right amount of glutamine(0.30%) can increase the number of intestinal goblet cells and lymphocyte count, excessive addition (1.20%)will lead to a significant decline in its (P<0.05); In the case of midgut no significant differences on the recessed depth and goblet cells of juvenile Grass Carp(P>0.05), Villus height and mucosa thickness increased of midgut from glutamine increased (P<0.05), excessive addition (1.20%)will lead to a significant decline in its (P<0.05). Based on the analysis discussion, glutamine optimum adding amount was 0.60%.Test two:The grass carp with an average body weight of 7.16±0.1g were randomly allocated into 5 groups with 3 replicates of 50 fish. Five practical diets were formulated to supply 0.00%,0.25%,0.50%,0.75%,1.00% glutamine dipeptide to the basal diet of grass carp, respectively. Each diet was randomly fed to triplicate groups of 50 fish per net cage (1.5 × 1.5× 1.5). The feeding trial lasted for 56 days. The results showed that:Fish fed diets with glutamine dipeptide supplementation had significantly increased in the final weight and the rate of weight gain (WGR) and specific growth rate(SGR) of juvenile grass carp, With the increasing of glutamine dipeptide, The feed coefficient rait(FCR) decreased firstly and then increased (P<0.05); The diets with glutamine dipeptide significantly increased the organ body (P<0.05), the coefficient of fatness firstly increased and then decreased (P<0.05). The lowest liver body ratio value was observed in fish fed the diet with levels of glutamine dipeptide(0.75%). the activities of lipase and trypsase decreased firstly and then increased (P <0.05). The fish achieved maximum value when fed diet with 0.25% glutamine dipeptide. Amylase activity was significantly lower than other groups. When supplemental levels of glutamine dipeptide was 1.00%, the activity of amylase were significantly lower than the control group (P<0.05). When the level were 0.50%,0.25%, the moisture content and crude protein reaches a minimum values (P<0.05). Glutamine dipeptide significantly increased the blood glucose(GLU), urea nitrogen(BUN), glutathione peroxidase(GSH-PX), total antioxidant capacity (T-AOC), cortisol, and significantly decreased the triglycerides (TG), alexin C4. The activity of LZM is highest when the adding amount was 0.50%. The activities of superoxide dismutase (SOD), catalase(CAT) were the lowest when the adding amount was 0.25%, respectively< 0.05). With the increasing levels of the glutamine peptide, total protein(TP), glutamic-oxalacetic transaminase (GOT), glutathione (GSH), malonaldehyde(MDA) increased firstly and then decreased. No significant differences on alexin C3, immunoglobulin(IGM), secreted immunoglobulin(A) S-LgA were observed. In the aspect of intestinal morphology, with the increasing levels of glutamine two peptide in the diets, the goblet cell number decreased with the addition increases of glutamine two peptide in foregut of Grass Carp, when the diet with levels of glutamine dipeptide(0.75%) the goblet cell number than the lowest value, but significantly increased number of lymphocytes. With the glutamine two peptide in the diets increased, increased firstly and then decreased of hidden recess depth and lymphocytes(P< 0.05), but dietary glutamine dipeptide can increase the thickness in the intestinal mucosa of the Ctenopharyngodon idellus add the right amount can significantly improve the number of intestinal goblet cells in juvenile Ctenopharyngodon idellus.