The Effect Of Enzymatic Protein On The Intestine Function And Immune Activity Of Juvenile Jian Carp (Cyprinus Carpio Var. Jian)

The effect of enzymatic protein on the intestine function and immune activity of juvenile Jian carp(cyprinus carpio Var.Jian) were studied in this trial. 900 Jian carps with initial weight 9.18 ± 0.06g were averagely allocated to 6 treatments with 3 replications per treatment, feeding diets with intact protein(IP) substituted by 0,20,40,60,80,100% enzymatic protein(EP) respectively. After 80-day feeding, a challenge trial was couducted by injection of Aeromonas Hydrophila(AH) for 17 day.The results showed that the weight gain . feed intake , feed conversion coefficient(FCR), proein retention ration(PRR), lipid retention ration , ash retention ration, intestine weight, intestine length, height of intestinal folds were significantly affected by dietary proportion of EP substitute IP(P<0.05). There were significant quadraticly relationship between weight gain ,PRR,or FCR and dietary EP level respectively (R₁²=0.9542,P<0.05, R₂²=0.8435,P<0.05 , R₃²=0.8981,P<0.05). The best growth and PRR, and lowest FCR appeared as the EP in the total protein were 42.25%, 44.57%, 43.46% respectively. The activity of protease, lipase,alkaline phosphatase (AKP), and Na⁺,K⁺-ATPase(ATPase) in intestine and glutamate- oxaloacetate transaminase (GOT)in muscle and hepatopancrease and ammonia content in plasma were affected by dietary proportion of EP substitute IP (P<0.05). The weight gain, feed efficiency, retention ration of protein and ash, intestine weight were increased as the EP proportion increasing(P<0.05), until to the IP replaced by 40% EP . The activity of lipase, protein content, AKP and ATPase of intestine, hepatopancrease weight, GOT in hepatopancrease increased ;while there was no difference in the protease activity of intesine as the dietary proportion of EP substitute IP increasing, until the EP in the dietary protein was 60% . The results of correlation analysis indicated that there were significant correlation between weight gain and feed intake, FCR, PRR(r₁=+0.9392,P<0.01, r₂= -0.9697, P<0.01, r₃=+0.9604, P<0.01). There were significant correlation between FCR and PRR,folds height of intestine,activity of lipase ,AKP,or ATPase (r₁= -0.9871, P<0.01, r₂= -0.8489,PO.01; r3= -0.8034, P<0.01;r4= -0.8583, PO.05; r5= -0.8584, PO.01 ;r6= -0.8942, P<0.01). The path-analysis results indicated that there were significant direct effect of feed intake , feed efficiency ,PRR on weight gain (path coefficient 0.4263, 0.3752 ^ 0.2367) (P<0.05) ,significant direct effect of PRR, ash retention ration on feed efficiency (path coefficient 0.860, 0.201) and significant direct effect of ATPase of intestine, ammonia content in plasma on PRR(path coefficient 0.8604, 0.2013) (PO.05).The survial of carp resistance to AH challeng, antibody content and anti-AH antibody titers of serum , leucocyte count > and phagocytosis of leucocyte were affected by dietary proportion of EP substitute IP. The antibody conten and anti-AH antibody titers increased with the increased dietary proportion of EP substitute IP(P<0.05). Surival resistance to AH challenge, leucocyte count, and phagocytosis of leucocyte, weight of head kidney and spleen were increased with the increased EP level, until the EP in the dietary protein was 60%. There were significant correlation between survival and antibody content, antibody titers in serum or phagocytosis of leucocyte (ri= -0.6645, P<0.05;r2= -0.9587, PO.01; r3= -0.8336, P<0.01; r4= -0.8312, P<0.01). Significant direct effect exist in anti-AH antibody titers and phagocytosis of leucocyte on survival resistance to AH challenge (path coefficient 0.4681, 0.2943) (PO.05).In summary, dietary IP substituted by EP could enhance the growth of carp by the increased feed intake and feed efficiency. The improvement of feed efficiency was due to the increased ability of digestion and absorption. The resistance ability of carp to disease enhanced as the dietary proportion of EP substitute IP increasing . Feed efficiency and growth decreased as the dietary proportion of EP substitute IP being over 60% . The gowth rate, feed efficiency and PRR of Juvenile Jian carps were best as proportion of this EP in total protein 42.52,44.57%,43.46% respectively, the phagocytosis of leucocyte and anti-AH antibody titers were highest as proportion of this EP in total protein 60%, 100% respectively.