The Effects Of Tea Polyphenol(TP) Feed Additive On Growth,Body Composition,Plasma Parameters,Antioxidant Responses And Immunity Capacity Of Genetically Improved Farmed Tilapia(GIFT)(Oreochromis Niloticus)

Tea polyphenol(TP)is one of the Chinese herbs most commonly used in the aquaculture sector.The intention of this study was to study the effects of this herb on growth enhancement,feed utilization and conversion,entire body chemical structure,antioxidant activity and immune responses of GIFT(Oreochromis niloticus).Before commencement of the experiment,six diets were formulated containing different inclusion levels of 0.00 mg/kg,100 mg/kg,200 mg/kg,300 mg/kg,400 mg/kg and 500 mg/kg tea polyphenol.Before commencing the feeding experiment,600 fish were initially kept in tanks(300L)for the period of two weeks to acclimatize the fish.Throughout this period,the fish were fed commercial diet for survival.At the end of the acclimatization period,15 apparently healthy juvenile fish of similar average weight(13.46 ± 1.25 g)were randomly distributed in quadruplicate(four replicates)in each of the six diets in tanks(150L)and fish were hand-fed three times daily at 5% of their body weight for 8 weeks.After the 8-week feeding trial,the fish fed with 100 mg/kg tea polyphenol showed higher final body weight(FBW),weight gain rate(WGR)and specific growth rate(SGR),which were not significantly(P > 0.05)different compared to control group fed 0.00 mg/kg,while the group fed with 500 mg/kg showed the lowest final body weight(FBW).Feed conversion ratio(FCR)was lower in the 100 mg/kg fed group but no significantly(P > 0.05)different observed compared to control group.The percent lipid content was slightly higher in the control group at 0.00 mg/kg but showed no significant difference(P > 0.05)from the other treatment groups.Percent moisture content was higher in the group fed 100 mg/kg.Percent moisture content showed significant difference(P < 0.05)from control group.Protein content was lower in the group fed 100 mg/kg and showed significant difference(P < 0.05)from the control group(0.00mg/kg).Based on the growth results and organ index results,the addition of low dose tea polyphenol(100 mg/kg,200 mg/kg)to the diet increased the weight gain rate(WGR),the specific growth rate(SGR)of juvenile tilapia,decreased the ratio of liver to body and viscera to body,improved the non-specific immune ability of the body to some extent,but at high dosage(more than 300 mg/kg)inhibited growth.Effects of dietary tea polyphenol(TP)on haemato-biochemical parameters,antioxidant responses and immunity of GIFT Tilapia(Oreochromis niloticus)This study was purposely conducted to assess the effects of dietary tea polyphenol on hematobiochemical parameters,antioxidant responses and body immunity in Oreochromis niloticus(GIFT).Blood samples were collected from four(4)fish from each tank,after rapid centrifugation at 4000 g at 4°C for 10 min,plasma was separated and collected.Biochemical analysis of the blood and antioxidant functions were studied in the laboratory.To study the morphological changes,the samples were scanned sequentially from anterior to posterior,then digital images of the affected regions were taken using Semaphore software.Feeding different amounts of tea polyphenol had a certain effect on blood physiology and biochemistry of tilapia.Among them,the addition of tea polyphenol significantly reduced the blood triglyceride content(TG)(P < 0.05).The level of alanine aminotransferase(ALT)in blood decreased significantly with the increase of dietary tea polyphenol(P < 0.05),when alanine aminotransferase(ALT)increases in the blood,it is an indication of liver damage.In addition,100 mg/kg tea polyphenol could effectively lower the level of Aspartate transaminase(AST)(P < 0.05).The addition of tea polyphenol in the diet of 400 mg/kg can decrease the serum complement Carbon fixation(C4)level,but the significantly(P > 0.05).Following addition of high dose of TP(400 and 500mg/kg)amount of feed additive to the fish diet,also the levels of superoxide dismutase(SOD),catalyze(CAT)and total antioxidant capacity(T-AOC)tended to increase significantly(P <0.05)in tilapia liver.However,in the low dose fed group(100 mg/kg)malondialdehyde(MDA)in the liver was significantly high(P< 0.05)compared to control group.Ten experimental fish per tank were collected,in order to cause acute liver injury,carbon tetrachloride(CCl4)was used by intraperitoneal injection of 0.5 ml solution(50%)per 100 g fish body weight.Death of fish was observed 6h,12 h,1d,2d,3d,4d,5d,6d and 7d after injection.The cumulative mortality induced by tetrachloride(CCl4)solution injection increased with the increase in the amount of tea polyphenol added to the diet.The cumulative mortality of control group 0.00mg/kg and that of 100 mg/kg group was significantly lower(P < 0.05)than that of 500 mg/kg group.During sampling,typical bile infiltration was observed in the liver of tilapia in the high dose group(400 mg/kg and 500 mg/kg),gallbladder and spleen enlargement,color deepening,digestive tract was fragile and easy to break,edema nodules and other phenomena.The staining of the apoptosis of tilapia intestinal and liver cells in the tissue,the nuclei of the injured apoptotic cells in the tissue are stained yellow-brown,and the normal nuclei are stained blue.The staining results showed that the number of apoptotic cells in the intestine and liver of tilapia decreased with the increase of the dosage of tea polyphenol(TP).According to the results of intestinal tissue section,the tea polyphenol has an obvious effect on the physiological function of the digestive tract of tilapia.Increasing the amount of tea polyphenol leads to edema,inflammatory injury and cell fibrosis in the digestive tract.