Effect Of Pantothenic Acid On Functions Of Digestion, Absorption And Immune Of Juvenile Jian Carp (Cyprinus Carpio Var. Jian)

This experiment was carried out to study the effects of dietary pantothenic acid(PA) levels on growth performance,functions of digestion,absorption and immune of juvenile Jian carp(Cyprinus carpio var.Jian).Semi-purified diets with seven levels,ie.44.00(3.51 mg PA kg^-1),15.48(15.00 mg PA kg^-1),25.56(25.00 mg PA kg^-1),36.10(35.00 mg PA kg^-1), 45.94(45.00 mg PA kg^-1),56.05(55.00 mg PA kg^-1) and 65.85(65.00 mg PA kg^-1),of supplemental calcium d-pantothenate were fed for 9 weeks to triplicate groups of 50 fish (initial weight 12.95±0.03 g,mean±SD).After the growth trial,30 fish in each treatment were randomly assigned to a challenge trial conducted by injection of Aeromonas hydrophila for 17 days.Results indicated that from 4-week Jian carp fed with the PA-unsupplemented diet gradually exhibited anorexia,poor growth,exophthalmus,hemorrhage of body surface and in the fins,sluggishness and severe hyperplasia of gill filaments,etc..Also PA significantly improved specific growth rate(SGR)(P＜0.01),feed intake(FI)(P＜0.01),protein efficiency ratio(PER)(P＜0.01),net protein utilization(NPU)(P＜0.01),lipid deposition (LDR)(P＜0.01),ash depostition(ADR)(P＜0.01),hepatopancreas weight(HSW) (P＜0.01),hepatopancreas protein content(HPC)(P＜0.01),intestine weight(ISW) (P＜0.01),intestine protein content(IPC)(P＜0.01),intestine length(IL)(P＜0.01), intestinal folds height(P＜0.01),activity of tryspin(P＜0.01),lipase(P＜0.01),amylase (P＜0.01),chymotrypsin(P＜0.01) in hapatopancreas and intestinal enzymes concerning absorption,containing alkaline phosphatase(AKP)(P＜0.01),Na⁺,K⁺-ATPase(P＜0.01), gamma-glutamyl transpeptidase(γ-GT)(P＜0.01) and creatine kinase(CK)(P＜0.01). Simultaneously,immune organ weight(P＜0.01),red blood counts(P＜0.01) and white blood counts(P＜0.01),survival after vaccination(P＜0.01),phagocytic activity of leucocytes(P＜0.01),immunoglobulin M(IgM) levels(P＜0.01),anti-AH antibody titers (P＜0.01),serum lectin titers(P＜0.01),serum complement C3 and C4 levels(P＜0.01), total iron-binding capacity(TIBC)(P＜0.01)and activity of serum acid phosphatase(ACP) (P＜0.01) and lysozyme(P＜0.01) were directly enhanced by graded PA levels.Moreover, quantities of Lactobacillus(P＜0.01),Escherichia colii(P＜0.01) and Aeromonas hydrophila(P＜0.01) in intestine were affected by dietary PA levels.Correlation analysis showed SGR,FE and nutrient deposition were all positive related to the growth and development of hepatopancreas and intestine and digestive enzyme activities,and survival after vaccination was directly correlated with serum IgM,anti-AH antibody titers, phagocytic activity of leucocytes,serum lysozyrae activity,serum ACP activity,serum iron binding capacity and Lactobacillus in intestine(r₁=+0.840,P＜0.05;r₂=+0.995,P＜0.01; r₃=+0.847,P＜0.05;r₄=+0.963,P＜0.01;r₅=+0.834,P＜0.05;r₆=+0.827,P＜0.05; r₇=+0.962,P＜0.01).Path analysis indicated FI and FE had significantly direct effects on weight gain(P_0.1=0.4601,d_0.1=0.2117,P＜0.01;P_0.2=0.5433,d_0.2=0.2952,P＜0.01),which demonstrated the promoted effects of dietary PA on the growth were closely to the enhanced feed intake and feed efficiency;trypsin activity in intestine and AKP activity in foregut had the direct effects on FE(P_0.1=1.3067,d_0.1=1.7075,P＜0.01;P_0.2=0.1616, d_0.2=0.02611,P＜0.05),however,there was a indirect effect of lipase activity in intestine on FE,which expressed PA improved FE by enhancing intestinal enzyme activities and promoting intestinal development;there were direct relationship between phagocytosis of leucocyte,bacteriolysisi of serum lysozyme and bacteriostasis of total iron-binding capacity and serum IgM responses and survival after vaccination(P_0.1=0.5959,d_0.1=0.3551, P＜0.01;P_0.2=2.0786,d_0.2=4.3206,P＜0.01;P_0.3=0.1826,d_0.3=0.03334,P＜0.05),but serum IgM had negative effects on survival after vaccination(P0.1=-1.8668,d.1=3.4849,P＜0.01) which meant there was a major indirect and positive correlation between them.exhibited anorexia,poor growth,exophthaimus and hemorrhage of body surface and in the fins and sluggishnessIn considering these results,Jian carp fed PA-deficient diets performed anorexia,poor growth,exophthalmus,hemorrhage of body surface and in the fins and severe hyperplasia of gill filaments,etc..PA promoted feed intake and feed efficiency through advancing the growth and development of digestive organs and the ability to secreting trypsin,lipase and amylase,and enhancing the absorbtion function of intestine to improve the ability to digesting and absorbing nutrients to so as to enhance the growth performance of Jian carp. At the same time,PA promoted phagocytosis of leucocyte and bacteriolysis of serum lysozyme and ACP,enhanced baeteriostasis of serum iron-binding capacity and increased Lactobacillus in intestine to depresse the reproduction of Escherichia colii and Aeromonas hydrophila in intestine in order to enhance non-specific immunity of Jian carp;PA promoted the growth of immune organs and enhanced the responses of serum specific antibody and IgM so as to enhance specific immunity,and further so to improve disease of resistance.By the broken-line analysis the optimum dietary pantothenic acid requirement for optimal growth,digestion function,non-specific immunity and specific immunity of juvenile Jian carp(12.95-73.00 g) was determined to be 23.02 mg/kg,28.95 mg/kg,42.16 mg/kg and 47.15 mg/kg,respectively.