Effect Of Dietary Folic Acid On The Growth Performance,Physiological And Biochemical Responses In Blunt Snout Bream,Megalobrama Amblycephala Fingerling Under Acute High Temperature Stress

This study investigated the effect of dietary folic acid on the growth performance,physiological and biochemical responses in blunt snout bream,megalobrama amblycephala fingerling under acute high temperature stress.The initial weight of blunt snout bream fingerling was 27.0±0.03g.Six semi-purified diets were formulated to contain graded levels of folic acid(0.0,0.5,1.0,2.0,5.0,and 10.0 mg/kg diets).The diets were administered for ten weeks and each diet was fed three replicate tanks of blunt snout bream fingerling in a re-circulated water system.Fish fed with 1.0,2.0 and 5.0 mg/kg diet of dietary folic acid supplemented diets significantly improved(p<0.05)final body weight,weight gain rate and specific growth rate.In addition,1.0mg/kg diet significantly influence feed conversion ratio and fulton condition factor in blunt snout bream fed for ten weeks.Viscerosomatic index and Hepatosomatic index were significantly enhanced by dietary folic acid at 2.0 and 1.0 mg/kg diet respectively.Muscle moisture,ash and crude lipid contents of blunt snout bream fingerlings fed with dietary folic acid for ten weeks were not significantly affected(P>0.05)with reference to the un-supplemented ones.Nevertheless,a significant difference(P<0.05)was observed in crude protein,and its content in the group fed with 1.0 and 2.0 mg/kg dietary folic acid was significantly higher than those fed with the control diet and 0.5 mg/kg dietary folic acid,but it was not significantly different from the other treatments.Based on the broken line-regression analysis of weight gain rate,specific growth rate and hepatosomatic index,the optimum dietary folic acid for blunt snout fingerlings was estimated to be 0.68,0.68 and 0.82 mg/kg,respectively.Blood hematology which include white blood cell(WBC),red blood cell(RBC),hemoglobin(HGB),hematocrit(HCT)and platelet(PLT)were not affected by fish fed with dietary folic acid for ten weeks.Fish fed with supplemented folic acid significantly enhanced amylase and lipase activity at 2.0mg/kg diet while trypsin and chemotrypsin were increased at 1.Omg/kg diet in blunt snout bream fingerling.Further,Serum total protein(TP),alanine aminotransferase(ALT),aspartate aminotransferase(AST),Urea,Triiodothyronine(T3),Thyroxine(T4),Adrenocorticotropic(ACTH),alkaline phosphatase(ALP),Triacyglycerol(TG),total cholesterol(TC),cortisol,glucose,complementC3(C3),complement C4(C4,immunoglobulin M(IgM)hepatic superoxide dismutase(SOD),catalase(CAT),malondialdehyde(MDA)and the expression of heat shock protein 60(HSP60),70(HSP70),and 90(HSP90)were studied understand acute high temperature stress.The results showed that serum total protein(TP),alkaline phosphate(ALP)and cortisol were significantly influenced by(P<0.05)dietary folic acid.Serum TP was significantly(P<0.05)increased at 1.Omg/kg while serum ALP and cortisol were significantly(P<0.05)reduced at 2.0mg/kg compared to the control before challenge experiment.After challenge experiment,serum TP was significantly(P<0.05)increased at 2.0mg/kg in Ohr challenge while in 24hrs it was significantly(P<0.05)increased at 1.0,2.0,and 5.0mg/kg compared to the un-supplemented diet.For 7days challenge,1.0mg/kg and 2.0mg/kg significantly increased serum TP compared to the control and 0.5mg/kg diet.Dietary folic acid significantly(P<0.05)reduced serum ALP at 1.0mg/kg in Ohr and in 24hrs challenge reduced at(P<0.05)1.Omg/kg and 2.0mg/kg compared to the control.In addition,72hrs and 7days dietary folic acid significantly reduced serum ALP at 1.0,2.0 and 5.0mg/kg compared to the control.In serum cortisol,2.0mg/kg was significantly(P<0.05)lower than control,0.5 and 10.0mg/kg for 24hrs and 72hrs challenge.Dietary folic acid at 1.0mg/kg significantly(P<0.05)reduced serum Alanine aminotransferase(ALT)in 24hrs challenge compared to the control and 10.0mg/kg.Also,dietary folic acid reduced serum Aspartate aminotransferase(AST)at 2.Omg/kg compared to the control in Ohrs challenge.Fish fed with 1.Omg/kg significantly reduced(P<0.05)serum glucose in Ohr and 72hrs stressed fish compared to the control while in 24hrs 1.0 and 2.0 mg/kg significantly lower(P<0.05)than the control.Before temperature challenge,fish fed with 1.0,2.0,5.0 and 10.0 successfully increased(P<0.05)serum complement C3 and C4 compared to the control and 0.5mg/kg while the highest(P<0.05)was observed at 1.0mg/kg in serum IgM compared to the control.After stressed,fish fed 2.0mg/kg higher(P<0.05)than control and 0.5mg/kg in Ohr while 5.0mg/kg higher(P<0.05)than control and 0.5mg/kg in 24hrs challenged fish for serum C3.Also,in 7days challenged fish 5.0mg/kg increased(P<0.05)serum C3 compared to the control.Serum C4 was significantly(<0.05)increased at 1.0and 2.0mg/kg compared to the control in Ohr challenged fish while in 24hrs serum C4 increased(P<0.05)at 1.0mg/kg compared to the control.Serum IgM significantly increased(P<0.05)at 2.0mg/kg in Ohr and 72hrs stressed fish compared to the control while in 2.0mg/kg higher(P<0.05)than control,0.5 and 10.0mg/kg in 7days challenged fish.Before challenge Malondialdehyde(MDA)activity in fish fed with folic acid un-supplemented diet was significantly higher than those fed with 1.0-5.0 mg/kg dietary folic acid,while the reverse was found in superoxide dismutase(SOD)activity(P<0.05).Significantly(P<0.05)higher catalase(CAT)activity was observed in fish fed with 5.0 mg/kg dietary folic acid diet compared to the un-supplemented ones,but it was not significantly(P>0.05)different from the other treatments.After challenge,at 1.0mg/kg significantly raised(P<0.05)liver SOD in Ohr challenged fish compared to the control and 0.5mg/kg while in 24hrs 1.0,2.0,and 5.0mg/kg significantly raised liver SOD compared to the control and 0.5mg/kg.In 7days challenged 1.0mg/kg increased liver SOD when compared to the un-supplemented diet.Before challenge,dietary folic acid at 2.0mg/kg significantly raised(P<0.05)Heat Shock Protein(HSP60)compared to the control while 1.0mg/kg significantly rose HSP70 when compared to the control.Also,before challenge,1.0mg/kg increased(P<0.05)liver HSP90 when compared to the control and 0.5mg/kg.After temperature stressed,2.0mg/kg raised(P<0.05)HSP60 when compared to the control in Ohr challenged while in 24hrs 1.0mg/kg was higher(P<0.05)than the control,1.0mg/kg also raised(P<0.05)HSP60 in 72hrs stressed fish when compared to the control 0.5 and 10.0mg/kg.Liver,HSP70 was successfully raised(P<0.05)at 2.0mg/kg in Ohr and 24hrs stressed fish when compared to the control whereas in 72hrs 1.0mg/kg was higher than control and 0.5mg/kg.In 7days challenged 1.0mg/kg increased(P<0.05)liver HSP70 when compared to the un-supplement diet and all treatments.For HSP90 after challenge,1.0mg/kg was higher(P<0.05)than control but not different from other treatments in 24hrs and 7days stressed fish.