Effects Of Dietary Taurine, Methionine, Cystine, Serine And Cysteamine On Growth Performance And Metabolism Of Taurine Synthesis In Turbot

This study focused on turbot (Scophthalmus maximus L.), an importantaquacultural fish. Some9-week or10-week trials were conducted to examine theeffects of dietary taurine, methionine, cystine, serine and cysteamine on feeding,growth, body composition, hepatosomatic histology and metabolism of taurinesynthesis in turbot (Scophthalmus maximus L.) in indoor flow-through culture systemwith200L or500L tanks.(1) the optimum inclusion of taurine was investigated byanalyzing feeding, growth and taurine distribution in turbot with three body weightfed semi-purified diets containing casein, gelatin and a small amount of fish meal asprotein source.(2) the abilities of taurine synthesis and synthesis pathes in vivo ofturbot was studied by analyzing growth performance, biochemical composition,hepatosomatic histology and two key rate-limiting enzyme activities in taurinesynthesis of turbot fed high plant protein diets containing soybean meal, wheat glutenmeal and a small amount of fish meal as protein source by adding different dosage oftaurine, methionine, cysteine, serine and cysteamine hydrochloride. The experimentalresults was summarized as follows:1.This experiment was conducted to examine the effects of taurinesupplementation in casein-based diet on feeding, growth, feed utilization, bodycomposition and taurine distribution of turbot (Scophthalmus maximus L.) with initialbody weight of6.3±0.01g,48.0±0.73g and165.9±5.01g. The basal dietcontained35%casein,11%gelatin and10%fish meal, which was supplemented with0.0%(control),0.5%,1.0%and1.5%taurine to formulate four isonitrogenous andisolipidic diets (Diet1(0.0%), Diet2(0.5%), Diet3(1.0%) and Diet4(1.5%)). Each dietwas randomly assigned to triplicate groups of30fish (6.3g),20fish (48.0g),15fish (165.9g), respectively. Fish were fed twice daily (06:30and18:30) to apparentsatiation for10weeks. The results showed that the feeding intake of fish with threeinitial body weight fed diets supplemented with0.5-1.0%taurine was significantlyhigher than that of fish fed the control diet (P<0.05). Dietary1.0-1.5%、0.5-1.5%、0.5-1.0%taurine supplementation significantly increased the final body weight,specific growth rate and feed efficiency rate of fish with initial body weight of6.3±0.01g、48.0±0.73g、165.9±5.01g, respectively (P<0.05); For turbot with initialbody weight of6.3g, the carcass protein content of fish fed the diet supplementedwith1.0%taurine was significantly higher than that of fish fed the control diet(P<0.05)..The crude ash content of fish fed diets with0.5-1.5%taurinesupplementation was significantly lower than that of fish fed the control diet (P<0.05).For turbot with initial body weight of48.0g, dietary0.5-1.5%taurinesupplementation significantly increased the carass protein content and significantlydecreased the crude lipid content of fish (P<0.05). For turbot with initial body weightof165.9g, the carass protein content of fish fed the diets supplemented with0.5-1.5%taurine was significantly higher than that of fish fed the control diet (P<0.05). Thecrude lipid content significantly increased with increasing dietary taurine (P<0.05).The crude ash content of fish fed the diet with1.5%taurine supplementation wassignificantly lower than that of fish fed the control diet (P<0.05); With the increase ofdietary taurine, the taurine contents in body, muscle, eye, brain and liver of turbotwith three initial body weight increased. The taurine contents in body, muscle, eye,brain and liver of fish (6.3g) fed the diets supplemented with1.0-1.5%taurine weresignificantly higher than those of fish fed the control diet (P<0.05), and dietarytaurine was well correlated with the taurine contents in body and tissues (r>0.785).The taurine contents in body, muscle of fish (48.0g) significantly increased withincreasing dietary taurine (P<0.05). The taurine content in eye of fish (48.0g) fed thediets supplemented with0.5-1.0%taurine was significantly higher than that of fish fedthe control diet (P<0.05), and lower than that of fish fed the diet supplemented with1.5%taurine (P<0.05). The taurine contents in brain and liver of fish (48.0g) fed thediets supplemented with1.0-1.5%taurine were significantly higher than those of fish fed the other diets (P<0.05). Dietary taurine was well correlated with the taurinecontents in body and tissues (r>0.918). The taurine contents in body, brain of fish(165.9g) significantly increased with increasing dietary taurine (P<0.05). The taurinecontent in muscle of fish (165.9g) fed diets with taurine inclusion was significantlyhigher than that of fish fed the control diet (P<0.05), and no significant difference wasfound among diets with taurine inclusion (P>0.05). The taurine content in eye of fish(165.9g) fed the diets supplemented with0.5-1.0%taurine was significantly higherthan that of fish fed the control diet (P<0.05), and lower than that of fish fed the dietsupplemented with1.5%taurine (P<0.05). The taurine content in liver of fish (165.9g)fed the diets supplemented with1.0-1.5%taurine were significantly higher than thatof fish fed the other diets (P<0.05). Dietary taurine was well correlated with thetaurine contents in body and tissues (r>0.936). Considering the above resultscomprehensively,1.0%,0.5%,0.5%taurine supplemented in casein-based diets isprobably optimal for growth of turbot with initial weight of6.3g,48.0g,165.9g,respectively; Dietary taurine is accumulated linearly in tissues and probably promotegrowth by increasing feeding and the deposit of protein.2.This experiment was conducted to examine the effects of dietary taurinesupplementation on feeding, growth, feed utilization, biochemistry composition,hepatosomatic histological structure and metabolism of taurine synthesis in turbot(Scophthalmus maximus L.)(2.0±0.01g) fed high plant protein diets. A fish-mealbased diet (72.5%FM) was used as the control diets (DFM). The basal diet (14.0%FM,23.0%soybean meal and30.0%wheat gluten meal) was supplemented withtaurine at0.0%(DPP),1.0%(DietT-1.0%),2.0%(DietT-2.0%) to formulate four dietsisonitrogenous and isolipidic diets. Each diet was randomly assigned to triplicategroups of42fish. Fish were fed twice daily (06:30and18:30) to apparent satiation for8weeks. The results showed that the feeding intake of fish fed DietT-1.0%,DietT-2.0%was significantly higher than that of fish fed DPP (P<0.05), lower thanthat of fish fed DFM (P<0.05), and no significant difference was found betweenDietT-1.0%and DietT-2.0%(P>0.05). The final body weight, specific growth rate offish fed DietT-1.0%were significantly higher than those of fish fed DPP, DietT-2.0% (P<0.05), and lower than those of fish fed DFM (P<0.05). Fish fed DietT-1.0%showed significantly higher feed efficiency rate than fish fed DietT-2.0%(P<0.05),and showed no significantly different feed efficiency rate with fish fed DPP and DFM(P>0.05); No significant difference was found in moisture, crude protein and crudelipid among treatments (P>0.05). Fish fed DietT-2.0%showed significantly higherash content than fish fed DietT-1.0%(P<0.05), and showed no significantly differentash content with fish fed DPP and DFM (P>0.05). The cellular morphology and cellveins in liver of fish fed diets with taurine inclusion was more clear than that of fishfed DPP, and closed to the case of fish fed DFM; The hepatosomatic taurine contentof fish fed diets with taurine inclusion was significantly higher than that of fish fedDPP (P<0.05), and not significantly different from that of fish fed DFM(P>0.05). TheL-cysteinesulfinate decarboxylase (CSD) activity in liver of fish fed DietT-2%wassignificantly lower than that of fish fed DPP (P<0.05), and not significantly differentfrom that of fish fed DietT-1%, DFM (P>0.05). The hepatic cysteamine dioxygenase(CDO) activity of fish fed diets with taurine inclusion was significantly lower thanthat of fish fed DPP (P<0.05), and not significantly different from that of fish fedDFM (P>0.05). In conclusion,1.0%taurine supplemented in high plant protein dietspromoted growth and feeding of turbot. The taurine supplementation in dietsimproved the hepatosomatic histological structure, increased the taurine content andinhibited the activities of CSD and CDO in liver.3.This experiment studied the effects of dietary methionine supplementation onfeeding, growth, feed utilization, biochemistry composition, hepatosomatichistological structure and metabolism of taurine synthesis in turbot (Scophthalmusmaximus L.)(2.0±0.01g) fed high plant protein diets. A fish-meal based diet (72.5%FM) was used as the control diets (DFM). The basal diet (14.0%FM,23.0%soybeanmeal and30.0%wheat gluten meal) was supplemented with methionine at0.0%(DPP),0.2%(DietM-1.0%) and1.2%(DietM-2.0%) to formulate four dietsisonitrogenous and isolipidic to the control diet. Each diet was randomly assigned totriplicate groups of42fish. Fish were fed twice daily (06:30and18:30) to apparentsatiation for8weeks. The results showed that the feeding intake, feed efficiency rate of fish fed DietM-1.0%, DietM-2.0%showed no significant difference with those offish fed DPP and DFM (P<0.05). The final body weight, specific growth rate of fishfed DietM-1.0%, DietM-2.0%were significantly higher than those of fish fed DPP(P<0.05), lower than those of fish fed DFM (P<0.05), and not significantly differentfrom those of fish fed DFM (P>0.05); Fish fed DietM-1.0%showed significantlyhigher ash content than fish fed DPP (P<0.05), lower ash content than fish fedDietM-2%(P<0.05), and showed no significantly different ash content with fish fedDFM (P>0.05). No significant difference was found in moisture, crude protein andcrude lipid among treatments (P>0.05); The cellular morphology and cell veins inliver of fish fed diets with methionine inclusion was more clear than those of fish fedDPP, and closed to the case of fish fed DFM; The hepatosomatic taurine content offish fed DietM-2%was significantly higher than that of fish fed DPP, DietM-1%(P<0.05), and not significantly different from that of fish fed DFM (P>0.05). Thehepatic cysteamine dioxygenase (CDO) activity in liver of fish fed DietM-2%wassignificantly lower than that of fish fed the control diet (P<0.05). TheL-cysteinesulfinate decarboxylase (CSD) activity in liver of fish fed diets with1-2%methionine inclusion showed no significant decrease (P>0.05). Considering theresults above,1.0%methionine supplemented in high plant protein diets promotedgrowth and increased ash content of turbot; Taurine added in diets improved thehepatosomatic histological structure, decreased the hepatosomatic CSD activitysignificantly.4.This experiment studied the effects of dietary cystine supplementation onfeeding, growth, feed utilization, biochemistry composition, hepatosomatichistological structure and metabolism of taurine synthesis in turbot (Scophthalmusmaximus L.)(2.0±0.01g) fed high plant protein diets. A fish-meal based diet (72.5%FM) was used as the control diets (DFM). The basal diet (14.0%FM,23.0%soybeanmeal and30.0%wheat gluten meal) was supplemented with cystine at0.0%(DPP),0.5%(DietC-1.0%) and1.5%(DietC-2.0%) to formulate four diets isonitrogenous andisolipidic to the control diet. Each diet was randomly assigned to triplicate groups of42fish. Fish were fed twice daily (06:30and18:30) to apparent satiation for8weeks. The results showed that the feeding intake, feed efficiency rate, specific growth rate offish fed DietC-1.0%, DietC-2.0%showed no significant difference with those of fishfed DPP (P<0.05), but significantly lower than those of fish fed DFM (P<0.05); Fishfed DietC-1.0%, DietC-2.0%showed no significantly different moisture content withfish fed DPP (P>0.05), but fish fed the three diets showed significantly highermoisture content than fish fed DFM (P<0.05). The ash content of fish fed DietC-1.0%,DietC-2.0%was significantly higher than that of fish fed DPP (P<0.05), and showedno significant difference with that of fish fed DFM (P>0.05). No significantdifference was discovered among treatments with respect to crude protein and lipidcontent (P>0.05); The cellular morphology and cell veins in liver of fish fed dietswith cystine inclusion was not improved notably; The hepatosomatic taurine contentand L-cysteinesulfinate decarboxylase (CSD) activity in liver of fish fed diets withcystine inclusion showed no significant increase (P>0.05). The hepatic cysteaminedioxygenase (CDO) activity in liver of fish fed DietC-1%was significantly higherthan that of fish fed DietC-0%(P<0.05). Considering the results, cystinesupplementation in high plant protein diets showed no improvement on growthperformance, hepatosomatic histological structure. But dietary cystine significantlyincreased the ash content and CDO activity in liver of turbot.5.This experiment studied the effects of dietary serine supplementation on feeding,growth, feed utilization, biochemistry composition, hepatosomatic histologicalstructure and metabolism of taurine synthesis in turbot (Scophthalmus maximus L.)(2.0±0.01g) fed high plant protein diets. A fish-meal based diet (72.5%FM) wasused as the control diets (DFM). The basal diet (14.0%FM,23.0%soybean meal and30.0%wheat gluten meal) was supplemented with serine at0.0%(DPP),1.5%(DietS-3.0%) to formulate three diets isonitrogenous and isolipidic to the control diet.Each diet was randomly assigned to triplicate groups of42fish. Fish were fed twicedaily (06:30and18:30) to apparent satiation for8weeks. The results showed that thefeeding intake of fish fed DietS-3.0%was significantly higher than that of fish fedDPP (P<0.05), and not significantly different from that of fish fed DFM (P>0.05). Nosignificant difference was shown among treatments with respect to feed efficiency rate (P>0.05), and no significant difference in specific growth rate was shownbetween fish fed DietS-3.0%and DPP (P>0.05), which was both significantly lowerthan that of fish fed DFM (P<0.05); Fish fed DietS-3.0%and DPP showedsignificantly higher moisture content than fish fed DFM (P<0.05). The ash content offish fed DietS-3.0%was significantly higher than that of fish fed DPP (P<0.05), andwas no significantly different from that of fish fed DFM (P>0.05). No significantdifference was discovered among treatments with respect to crude protein and lipidcontent (P>0.05); The cellular morphology and cell veins in liver of fish fed dietswith serine inclusion was more clear than that of fish fed DPP; The hepatic taurinecontent and L-cysteinesulfinate decarboxylase (CSD) activity in liver of fish fed dietswith serine inclusion showed no significant difference with those of fish fed the otherdiets (P>0.05). The hepatic cysteamine dioxygenase (CDO) activity in liver of fishfed DietS-3%was not significantly higher than that of fish fed DietS-0%(P>0.05),and was significantly higher than that of fish fed DietS-0%(P<0.05). Considering theresults, serine supplementation in high plant protein diets increased feeding and ashcontent. Dietary serine improved hepatosomatic histological structure of turbot, but nochange was shown in taurine content, CSD and CDO activity in liver.6.This experiment studied the effects of dietary cysteamine hydrochloridesupplementation on feeding, growth, feed utilization, biochemistry composition,hepatosomatic histological structure and metabolism of taurine synthesis in turbot(Scophthalmus maximus L.)(2.0±0.01g) fed high plant protein diets. A fish-mealbased diet (72.5%FM) was used as the control diets (DFM). The basal diet (14.0%FM,23.0%soybean meal and30.0%wheat gluten meal) was supplemented withcysteamine hydrochloride at0.0%(DPP),0.05%(DietCS-0.05%),0.1%(DietCS-0.1%) and0.15%(DietCS-0.15%) to formulate five diets isonitrogenous andisolipidic to the control diet. Each diet was randomly assigned to triplicate groups of42fish. Fish were fed twice daily (06:30and18:30) to apparent satiation for8weeks.The results showed that the feeding intake of fish fed DietCS-0.05%was significantlyhigher than that of fish fed DPP (P<0.05), and not significantly different from that offish fed DFM (P>0.05). No significant difference was shown among treatments with respect to feed efficiency rate (P>0.05), and no significant difference in specificgrowth rate was found among fish fed diets with cysteamine hydrochloride inclusion(P>0.05), which was all significantly lower than that of fish fed DFM (P<0.05); Theash content of fish fed DietCS-0.05%was significantly higher than that of fish fedDPP (P<0.05), and showed no significant difference with that of fish fed DFM(P>0.05). No significant difference was discovered among treatments with respect tocrude protein and lipid content (P>0.05); The cellular morphology and cell veins inliver of fish fed diets with cysteamine hydrochloride inclusion was more clear thanthose of fish fed DPP; The taurine content in liver of fish fed diets supplemented with0.05-0.15%cysteamine hydrochloride was not significantly higher than that of fishfed DPP (P<0.05). The cysteamine dioxygenase (CDO) activity in liver of fish feddiets with cysteamine hydrochloride inclusion was significantly higher than that offish fed DFM (P<0.05), but was not significantly different from that of fish fed DPP(P>0.05). The L-cysteinesulfinate decarboxylase (CSD) activity in liver of fish feddiets with0.05-0.15%cysteamine hydrochloride showed no significant change(P>0.05). Considering the results comprehensively,0.05%cysteamine hydrochloridesupplementation in high plant protein diets increased feeding and ash content; Dietarycysteamine hydrochloride improved hepatosomatic histological structure, increased inliver, but showed no significant change in taurine content, hepatic CDO and CDOactivity of turbot.