Effect Of Lysine On Digestion And Immune Function Of Juvenile Jian Carp (Cyprinus Carpio Var.Jian)

Two experiments were conducted to study the effect of lysine on digestion and immune function of juvenile Jian Carp (Cyprinus carpio Var. Jian). In trial Ⅰ, 495 juvenile Jian carps(initial weight 7. 89 ± 0. 04g) were randomly allocated to 3 groups, feeding control diet or control diet containing uncoated or control diet containing coated lysine respectively for 80 d. In trial Ⅱ, 990 juvenile Jian carps(initial weight7. 89±0. 04g) were randomly allocated to 6 groups feeding semi-purified diets containing lysine 0.7, 1.0, 1.3, 1.6, 1.9, 2.2% respectively for 80 d. After 80d, a challenge trial was conducted by injection of Aeromonas Hydrophila(AH) for 17 day.In trial Ⅰ , weight gain, feed intake, feed conversion efficiency, protein retention ration increased significantly as diet added with lysine(P<0.01), The efficiency of coated lysine was better than uncoated lysine. Weight gain, feed intake, feed conversion efficiency, protein retention ratio, lipid retention ratio, ash retention ratio, intestinal weight, intestinal protein , intestinal folds height, hepatopancrease weight/body weight, activity of intestinal protease, lipase , alkaline phosphatase , Na+, K+-ATPase , head kidney weight, spleen weight, serum antibody titers after vaccination against Aeromonas hydrophila (AH) increased significantly (P<0.01or0.05), glutamine-oxaloacetate transaminase in muscle, plasma ammonia decreased significantly (P<0. 01) in juvenile Jian carps fed diet with coated lysine compared to carps fed diet with uncoated lysine. The results of digestion in vitro indicated that lysine leaving from uncoated lysine or coated lysine all ,after 1h or 3h.In trial Ⅱ,lysine level, feed intake , feed conversion ratio, protein retention ratio, significantly affected weight gain and linely correlated with weight gain (rl=±0. 982, P<0.01; r2= +0.997, P<0. 01; r3=-0.967, p<0.01; r4=+0. 987, P<0.01). And lysine level, feed intake , feed conversion efficiency affect weight gain directly (path coefficient 0. 320, 0. 504, 0.183). Intestinal folds height, intestinal protease, lipase , alkaline phosphatase , Na+, K+-ATPase activities linely correlated with feed conversion ratio (rl= -0.940,P<0. 05; r2= -0.992, P<0. 01; r3= -0. 986, P<0. 01; r4= -0. 886, P<0. 05; r5= -0. 988, P<0.01) , intestinal protease and lipase activity affect feed conversion efficiency directly (path coefficient 0. 490, 0.476). Serum antibody level and titers against AH, serum lysozyme content ,phago-ratio of leukocyte linely correlated with survival ratio (rl= +0.930, P<0.01;r2= +0.996, P<0. 01; r= +0.993, P<0.01; r= +0.993, p<0.01) . Serum lysozyme and antibody titers affect survival ratio directly(path coefficient 0.447,0.319).In summary, the growth performance and immune function of juvenile Jian carps increased through adding lysine in the diet, and the effect of coated lysine was better than uncoated lysine. The growth rate increased by increasing feed intake and feed conversion efficiency. The ability of digestion and absorption and Immune function were enhanced as carps fed diet adding coated lysine. In a diet for 7-36g juvenile Jian carps with a total protein level of 32%, carps appeared best growth performance as feeding the diets containing lysine 1.88% or 5.87g/100gCP and best non-specific or specific immune ability of carp appeared as feeding the diets containing lysine 1.60% or 5. OOg/lOOgCP, 1.45% or 4. 52g/100gCP.