Studies On Nutritional Physiology Of Mineral Element (K,Mg,Se,Cu) And Carbohydrate In Abalone (Haliotis Discus Hannai Ino)

A detailed review of studying status on nutritional physiology of mineral elementK,Mg,Se,Cu and carbohydrate in aquatic animals was undertaken.A series ofexperiments were conducted to discuss the effect of mineral element K,Mg,Se,Cuand carbohydrate on growth performance and carbohydrate metabolism response inabalone Haliotis discus hannai Ino.The current studies include the followings:(1)Dietary potassium requirement and physiological responses of juvenile abalone,Haliotis discus hannai Ino.(2) Dietary magnesium requirement and physiologicalresponses of juvenile abalone,Haliotis discus hannai Ino.(3) The interaction ofdietary magnesium and protein level on growth and carcass composition of juvenileabalone,Haliotis discus hannai Ino.(4) Immune responses to dietary selenium andselenium requirement of abalone,Haliotis discus hannai Ino.(5) Immune responses todietary copper and copper requirement of abalone,Haliotis discus hannai Ino.(6)Effect of dietary carbohydrate sources on growth performance and carbohydratemetabolism in abalone,Haliotis discus hannai Ino.(7) Effect of dietary carbohydratesources on lipid and fatty acid metabolic responses in abalone,Haliotis discus hannaiIno.The results are summarized as follows:(1) A one-factorial experiment was conducted to determine the effects ofdietary potassium on growth,survival and carcass composition of juvenile abalone,Haliotis discus hannai Ino,to evaluate the minimum requirement of dietary potassiumand to study the physiological responses of abalone to dietary potassium in long termacclimation using a premium quality diet based on casein-gelatin as the proteinsources.Six semipurified diets containing graded levels of dietary potassium (0,2,4,8,16,32 g/kg providing 0.10±0.01,2.12±0.02,4.39±0.53,9.79±1.00,20.08±1.14,27.26±1.72 g/kg dry diet) were fed to juvenile abalone (average initial shell length:12.24±0.04 mm;average initial weight:0.24±0.00 g) in triplicate groups for 15 weeks in a flow-through system.During the experimental period,the water temperatureranged from 12 to 23℃and potassium concentration was 472.94±3.59 mg/l in the seawater.The results showed that there were no significant differences in the averageweight gain rate (WGR,%),daily increment in shell length (DISL,μm/day) and thesurvival of abalone among six dietary treatments (P＞0.05).There were also nosignificant differences in lipid,moisture contents of soft body and the content of shellash among six dietary treatments (P＞0.05),but the soft body protein content wassignificantly increased when the supplementation of dietary potassium was more than4 g/kg diet,compared with the treatment of 0 g/kg diet (P＜0.05).The content ofpotassium in the soft body and potassium,sodium in the shell was maintainedrelatively constant regardless of dietary treatment (P＞0.05);the soft body sodiumcontent,however,was significantly lower in 16 and 32 g K/kg diet than any othertreatments (P＜0.05).The activity of gill Na⁺-K⁺ ATPase was decreased steadily withthe rising of dietary potassium.These data indicated that it seems no necessary to addpotassium to the diet and the potassium in diet and sea water is sufficient for optimumgrowth for abalone;there is no apparent dose-response relationship between dietarypotassium level and whole body potassium concentration;the soft body sodiumcontent and the gill Na⁺-K⁺ ATPase activity were decreased when juvenile abalonewere in long term acclimation with high potassium level diets.(2) A one-factorial experiment was conducted to determine the effects ofdietary magnesium on growth,survival and carcass composition of juvenile abalone,Haliotis discus hannai Ino,to evaluate the minimum requirement of dietarymagnesium using a premium quality diet based on casein-gelatin as the proteinsources and to study the physiological responses of abalone to dietary magnesium inlong term acclimation.Six semi-purified diets containing graded levels of dietarymagnesium (0,0.3,0.6,1.2,2.4,4.8 g/kg providing 0.12±0.12,0.81±0.02,1.49±0.04,2.56±0.04,5.06±0.10,9.41±0.10 g/kg dry diet) were fed to juvenile abalone (averageinitial shell length:12.12±0.05 mm;average initial weight:0.23±0.00 g) in triplicategroups for 15 weeks in a flow-through system.During the experimental period,thewater temperature ranged from 12 to 23℃and magnesium concentration was152.75±1.86 mg/1 in the sea water.The results showed that there were no significantdifferences in the average weight gain rate (WGR,%),daily increment in shell length(DISL,μm/day) and the survival of abalone among six dietary treatments (P＞0.05). There were no significant differences in lipid,moisture contents of soft body and thecontent of shell ash among six dietary treatments (P＞0.05),but the soft body proteincontent were significantly raised with the rising of dietary magnesium and with thehighest value in the treatment of 0.6 g Mg/kg dry diet.The activity of gill,hepatopancreas and muscle Mg²⁺-ATPase was significantly (P＜0.05) affected by thedietary magnesium,the highest value of gill,hepatopancreas Mg²⁺-ATPase appearedin the 0.3 g Mg/kg dry diet treatment while the muscle Mg²⁺-ATPase in the treatmentof 0.6 g Mg/kg dry diet.The content of magnesium and calcium in the soft body andshell was maintained relatively constant regardless of dietary treatment (P＞0.05);thesoft body phosphorus content,however,was declined steadily with the increasing ofdietary magnesium.These data indicated that it seems no necessary to add magnesiumto the diet and the magnesium in diet and sea water is sufficient for optimum growthfor abalone;there is no apparent dose-response relationship between dietarymagnesium level and whole body magnesium and calcium concentration;the proteincontent in soft body and Mg²⁺-ATPase activity in gill,hepatopancreas and musclewere decreased when juvenile abalone were in long term acclimation with highmagnesium level diets;the phosphorus content in soft body was also decreased whenjuvenile abalone were fed high level of dietary magnesium.(3) A two-factorial experiment was conducted to determine the effects ofdietary magnesium and protein on growth,survival and carcass composition ofjuvenile abalone,Haliotis discus hannai Ino.Eight semi-purified diets containinggraded levels of dietary magnesium (0,0.3,1.2,2.4g/kg) with either 30 or 45%protein were fed to juvenile abalone (average initial shell length:12.12±0.00 mm;average initial weight:0.23±0.00 g) in triplicate groups for 15 weeks in aflow-through system.During the experimental period,the water temperature rangedfrom 12 to 23℃and magnesium concentration was 152.75±1.86 mg/l in the seawater.The results showed that there were no significant differences in the averageweight gain rate (WGR,%),daily increment in shell length (DISL,μm/day) and thesurvival of abalone among eight dietary treatments (P＞0.05).The interaction betweendietary magnesium and protein on the soft body protein content was significant(P＜0.05);the level of dietary protein only significantly influenced the lipid and shellash content of soft body (P＜0.05);there was no significant difference in water contentof soft body in all treatments (P＞0.05).The soft body magnesium content was only affected by dietary protein level,and has an increased trend with the increasing ofdietary protein level.There was significant interaction between dietary magnesiumand protein on the content of soft body calcium (P＜0.05),abalones fed 45% proteindemonstrated the significant higher soft body calcium content as compared with thosefed 30% protein;at the level of 45% protein,an increased level of dietary magnesiumresulted in significantly increased soft body calcium content.The soft bodyphosphorus content was steadily decreased with increasing dietary magnesiumcontent,however,the interaction between dietary magnesium and protein on the softbody phosphorus content was not significant (P＞0.05).The content of magnesium inthe shell was maintained relatively constant regardless of dietary treatment (P＞0.05);the content of calcium in the shell had an increased trend with the increasing ofdietary magnesium in both dietary protein level.In summary,dietary magnesium andprotein level had no significant effect on the growth performance of abalone,however,the increasing level of dietary magnesium and protein resulted in the increaseddeposition of calcium and protein content in soft body correspondingly,meanwhile,the soft body phosphorus content was steadily decreased with increasing dietarymagnesium content.(4) A study was designed to determine the effects of dietary selenium ongrowth,survival,carcass composition and serum immune index in juvenile abalone,Haliotis discus hannai Ino.Six semi-purified diets containing graded levels of dietaryselenium (supplementation of 0,0.3,0.6,1.2,2.4,9.6 mg/kg providing 0.15,0.53,0.88,1.55,2.63,9.16 mg Se/kg diet) were fed to juvenile abalone (average initialshell length:17.43±0.04 mm;average initial weight:0.68±0.00 g) in triplicate groupsfor 24 weeks in a flow-through system.During the experimental period,the watertemperature ranged from 10 to 20℃and selenium concentration was 1.46μg/l in thesea water.The results of the present study indicated that the highest values of averageweight gain rate (WGR,%) and daily increment in shell length (DISL,μm/day) wereappeared in 0.88 and 1.55 mg Se/kg diet treatments respectively,however,the 9.16mg Se/kg diet treatment showed the significantly lowest values in WGR and DISLthan 1.55 mg Se/kg diet treatments (P＜0.05).There was no significant difference inmoisture content,crude protein,crude lipid and crude ash of soft body in alltreatments (P＞0.05).The immune indexes showed that the activities of serumglutathione peroxidase (GPx) was significantly increased with the rising content of dietary selenium (P＜0.05) and reached the highest value in 2.63 mg Se/kg diettreatment,meanwhile,the highest activities of superoxide dismutase (SOD),phenoloxidase (PO) and lysozyme (LSZ) in serum were found in 0.88 and 1.55 mgSe/kg diet treatments respectively,but the serum protein content maintained relativelyconstant regardless of dietary treatments (P＞0.05).These results demonstrate thatsupplementary selenium in the diet could significantly affect the growth performanceand immune status of abalone.Broken-line regression analysis of weight gain rate(WGR) and daily increment in shell length (DISL) indicates that the optimal Serequirement for abalone is 1.17 and 1.09 mg Se/kg diet,respectively.It also reportsthe toxicity of selenium to abalone which appeared to be depressed growthperformance and the significantly decreased activities of serum SOD,PO and LSZ.(5) A study was designed to determine the effects of dietary copper on growth,survival,carcass composition and immune response in juvenile abalone,Haliotisdiscus hannai Ino.Six semi-purified diets containing graded levels of dietary copper(0,3,6,15,30,120 mg/kg providing 1.08,3.76,6.54,14.80,26.84,109.41 mg Cu/kgdiet) were fed to juvenile abalone (average initial shell length:17.21±0.04 mm;average initial weight:0.65±0.00 g) in triplicate groups for 24 weeks in a flow-through system.During the experimental period,the water temperature ranged from10 to 20℃and copper concentration was not detectable in the sea water.As the result,no significant differences were found in average weight gain rate (WGR,%),dailyincrement in shell length (DISL,μm/day) and survival of abalone among six dietarytreatments (P＞0.05).There was no significant difference in water content and crudeash of soft body in all treatments (P＞0.05).The crude protein content in soft body hada increased trend with the increasing of dietary copper level,and reached the highestvalue in the 109.41 mg Cu/kg diet group which was significantly higher than1.08-14.80 mg Cu/kg diet groups (P＜0.05).The crude lipid content in soft body had adeclined trend with the increasing of dietary copper level,the values in the 26.84 and109.41 mg Cu/kg diet groups were significantly lower than any other groups (P＜0.05).The immune indexes showed that the activities of hepatopancreas CuZn superoxidedismutase (CuZn SOD),serum CuZn.SOD and serum phenoloxidase (PO) were allincreased with the increasing supplementation of dietary copper,and the highest valuewere found in 3.76 and 6.54 mg Cu/kg diet groups,respectively.The serum proteincontent were increased with the increasing supplementation of dietary copper,and the highest value were found in 109.41 mg Cu/kg diet groups.The lysozyme activities ofserum maintained relatively constant regardless of dietary treatments (P＞0.05).Insummary,trace element copper is necessary for abalone,the adequate dietary copperconcentration in juvenile abalone is about 3.76 mg/kg based on the activity ofhepatopancreas and serum CuZn SOD;with the 6.54 mg Cu in per kilogram diet,abalone could maintain better immune response;It is also reported in this article thatabalone has a higher tolerance for dietary copper and do not show negative responseon growth performance at such high dietary copper level (109.41 mg/kg).(6) A one-factorial experiment was conducted to determine the effects ofdietary carbohydrate sources on growth,physiological & biochemical indexes inabalone,Haliotis discus hannai Ino,to evaluate the ability of abalone to utilize thedietary polysaccharides and carbohydrate metabolism in abalone using a premiumquality diet based on casein-gelatin as the protein sources.Six semi-purified dietscontaining 33.5% level of different carbohydrate sources (dextrin,pre-extrude wheatstarch,wheat starch,corn starch,tapioca starch,potato starch) were fed to abalone(average initial shell length:29.98±0.09 mm;average initial weight:3.42±0.02 g)in triplicate groups for 24 weeks in a recirculation system.During the experimentalperiod,the water temperature ranged from 18 to 20℃.The results showed that therewere no significant differences in the average daily increment in shell length (DISL,μm/day) and survival of abalone among six dietary treatments (P＞0.05),butsignificant differences were observed in the average final weight and weight gain rate(WGR,%) (P＜0.05),the poorest final weight and WGR were appeared in potatostarch group.There were also significant differences in water content,crude protein,crude ash of soft body and the content of shell crude ash among six dietary treatments(P＜0.05),but no variation was found in the soft body lipid content (P＞0.05).Theabalone fed the diet containing dextrin had the highest plasma glucose level comparedwith other groups.The abalone fed with pre-extrude wheat starch had the highestmuscle glycogen content,while the lowest content was appeared in potato starchgroups;however,the hepatopancreas glycogen content maintained relatively constantregardless of dietary carbohydrate sources (P＞0.05).The activities of hepatopancreasamylase and glucosidase in abalone fed the diets containing dextrin and potato starchshowed the lowest values,however,the hepatopancreas protease activities werereached the highest values in the abalone fed tapioca starch.Hepatopancreas hexokinase activity was lowest in abalone fed with dextrin.The serum andhepatopancreas insulin content declined simultaneously in abalone fed the dietcontaining potato starch.These data indicated that the abalone was able to efficientlyutilize dextrin,pre-extrude wheat starch,wheat starch,corn starch and tapioca starchused in present study,but showed different metabolic responses to thesecarbohydrates.(7) A one-factorial experiment was conducted to determine the effects ofdietary carbohydrate sources on lipid and fatty acid content in abalone,Haliotisdiscus hannai Ino,to evaluate the ability of abalone to utilize the dietarypolysaccharides and carbohydrate metabolism in abalone using a premium quality dietbased on casein-gelatin as the protein sources.Six semi-purified diets containing33.5% level of different carbohydrate sources (dextrin,pre-extrude wheat starch,wheat starch,corn starch,tapioca starch,potato starch) were fed to abalone (averageinitial shell length:29.98±0.09 mm;average initial weight:3.42±0.02 g) intriplicate groups for 24 weeks in a recirculation system.During the experimentalperiod,the water temperature ranged from 18 to 20℃.The results showed that theserum triglyceride and cholesterol content in abalone fed dextrin,pre-extruded wheatstarch and wheat starch were higher than any other treatments.The n-3 and n-6 seriespolyunsaturated fatty acids (PUFAs) content in the muscle and hepatopancreas ofabalone fed potato starch,tapioca starch,corn starch and wheat starch were higherthan that fed dextrin and pre-extruded wheat starch except that the muscle 18:3n-3content in abalone fed tapioca and potato starch which were significantly lower thanany other treatments (P＜0.05);the abalone fed the diet containing dextrin showed thelowest content of saturated fatty acid 18:0 in the muscle and hepatopancreas,theabalone fed the diet containing corn starch showed the lowest content of saturatedfatty acid 16:0 only in the hepatopancreas.These data indicated that the abalone wasable to efficiently utilize the dextrin,pre-extruded wheat starch and wheat starch asthe energy source;the increasing PUFAs content in abalone resulted from the starchused in this experiment such as potato starch,tapioca starch,corn starch and wheatstarch,leads to the pressure of lipid peroxidation in abalone.