| 1 An 8-week growth trial was conducted to determine the effects of dietary protein and lipid levels on growth,feed utilization,body and plasma biochemical compositions of hybrid grouper(Epinephelus lanceolatus ♂ × Epinephelus fuscoguttatus ♀)juveniles.Twelve experimental diets with the same estimated gross energy(360 kcal per 100 g dry matter)were formulated to contain 40%,45%,50%,or 55%dietary crude protein(CP)level(dry-matter basis)together with either 7%,10%,or 14%dietary crude lipid(CL)level,being abbreviated as P40/L7,P45/L7,P50/L7,P55/L7,P40/L10,P45/L10,P50/L10,P55/L10,P40/L13,P45/L13,P50/L13 and P55/L13,respectively.Juvenile fish(average initial weight of 4.68 ± 0.05 g/fish)were stocked as groups of 22 fish in floating cages(L 120 cm × W 70 cm × H 50 cm)placed in indoor 6-m3 concrete ponds with continuous sea water flow(salinity:33.1-g/L).From week 1 to week 8,fish in triplicate cages were fed each dietary treatment at rates of 9%,7%,5%,5%,4%,4%,3%and 3%of body weight(BW)/day,respectively.Weight gain(WG)of hybrid grouper fed the diet with 40%crude protein was significantly lower(P<0.05)than that of fish fed the diet with 45%,50%,or 55%CP while among fish fed 45%,50%and 55%dietary CP levels,WG did not display significant differences.Increasing dietary crude lipid from 7%to 13%had no significant influences(P>0.05)on growth performance of experimental fish.P40 fed fish exhibited significantly higher feed conversion ratio(FCR)than P45,P50 and P55 fed fish among which FCRs were not significantly different.Dietary CL levels did not affect FCR of experimental fish.Protein efficiency ratio(PER)was significantly decreased as dietary CP level increased.Fish fed 7%dietary CL had significantly thigher PER than fish fed 10%or 13%dietary CL.Values of hepatosomatic index(HSI)of fish fed P40 and P45 diets were significantly higher than those of fish fed P50 and P55 diets.Dietary CL levels did not cause significant changes in HSI.Intraperitoneal fat(IPF)ratios of fish had a reducing trend of variation as dietary CP was increased,but they were significantly increased when dietary CL was increased from 7%to 10%or from 10%to 13%.Fish fed 13%or 10%lipid had significantly higher whole-body lipid content than fish fed 7%lipid.Muscle lipid content increased as dietary CP or CL increased.Liver protein content had an increasing trend as dietary CP increased.Plasma cholesterol and high-density lipoprotein(HDL-C)had an increasing trend as dietary CP or CL increased.Fish fed 7%lipid had significantly lower plasma low-density lipoprotein(LDL-C)than fish fed 10%or 13%lipid.2 A 7-week growth trial was conducted to determine the the optimum dietary protein level of hybrid grouper(Epinephelus lanceolatus ♂× Epinephelus fuscoguttatus ♀)juveniles.seven experimental diets with the same estimated gross energy(360 kcal per 100 g dry matter)were formulated to contain 38%,42%,46%,50%,54%,58%,or 62%dietary crude protein(CP)level(dry-matter basis)together with 7%dietary crude lipid(CL)level,being abbreviated as P38,P42,P46,P50,P54,P58 and P62,respectively.Each diet was given to triplicate groups(22 fish per group,3.58±0.05 g/fish).Juvenile fish were stocked in floating cages(L 120 cm × W 70 cm× H 50 cm)placed in indoor 6-m3 concrete ponds with continuous sea water flow(salinity:33.1 g/L).The growth trial was continued for 7 weeks.Weight gain(WG)of hybrid grouper fed the diet with 38 and 42%crude protein was significantly lower(P<0.05)than that of fish fed the diet with 46%,50%,54%,58%or 62%CP,and fish fed he diet with 46%CP had significantly lower WG than fish fed the diet with 62%CP.Among fish fed 50%,54%,58%and 62%dietary CP levels,WG did not display significant differences(P ≥ 0.05).P38 fed fish exhibited significantly higher feed conversion ratio(FCR)than P46,P50,P58 and P62 fed fish,while P42,P46,P50 and P54 fed fish showed significantly higher FCR than P58 and P62 fed fish,FCRs of fish fed P38,P42 or fish fed P42,P46,P50,P54 had no significantly difference.Daily feed intake(DFI)of fish fed 38%CP was significantly higher than that of fish fed 50%,54%,58%and 62%CP.No significantly differences were found in DFI values among P38,P42,and P46 fed fish or among P42,P46,P50,P54,P58 and P62 fed fish.Both viscerosomatic indexes(VSI)and hepatosomatic index(HSI)showed a decreasing trend with increasing dietary CP levels.Muscle amino acids compositions except for serine(SER)showed no significant differences among all experimental treatments.SER content of fish fed P38 was significantly lower than that of fish fed the diet with P58 and P62,while this value for fish fed P42 was significantly lower than that of fish fed the diet with P62.Among fish fed P38,P42,P46,P50 and P54,or among fish fed P42,P46,P50,P54 and P58 as well as among fish fed P46,P50,P54,P58 and P62,SER content did not display significant differences.Based on the quadratic regression model at 95%of maximum response of WG,optimal dietary protein requirement of hybrid grouper(Epinephelus lanceolatus ♂ × Epinephelus fuscoguttatus ♀)juveniles was estimated to be 53.5%of dry matter.3 An 8-week growth trial was conducted to determine optimum protein to energy ratio of hybrid grouper(Epinephelus lanceolatus♂ × Epinephelus fuscoguttatus ♀).Experimental diets were formulated with seven energy values of 280,310,340,370,400,430 and 460 kcal per 100 g diet at 53.5%dietary crude protein level,forming protein to energy ratios of 191,173,157,145,134,124 and 116 mg/kcal,{being abbreviated as P/E(191),P/E(173),P/E(157),P/E(145),P/E(134),P/E(124)and P/E(116)respectively}.Each diet was given to triplicate groups(15 fish per group,10.98±0.05 g/fish).Juvenile fish were stocked in floating cages(L 120 cm × W 70 cm x H 50 cm)placed in indoor 6-m3 concrete ponds with continuous sea water flow(salinity:33.1 g/L).The growth trial was continued for 8 weeks.WG of hybrid grouper fed the diet with P/E(191)was significantly lower than that of fish fed the diet with P/E(173)and P/E(157)while among fish fed diets with P/E(191),P/E(145),P/E(134),P/E(124)and P/E(116)or among fish fed diets with P/E(17.3)and P/E(15.7),WG did not display significant differences.P/E(191)fed fish exhibited significantly higher feed conversion ratio(FCR)than P/E(157),P/E(145),P/E(134),P/E(124)or P/E(116)fed fish while P/E(173)fed fish showed significantly higher FCR than P/E(124)or P/E(116)fed fish.DFI values of Fish fed P/E(191)and P/E(173)were significantly higher than those of fish fed P/E(134),P/E(124)and P/E(116).PPV of fish fed P/E(191)was significantly lower than fish fed P/E(157)or P/E(145)while this value for fish fed P/E(173)was significantly lower than fish fed P/E(157).Both VSI and IPF showed a significant increasing trend with decreasing dietary P/E ratios.Whole body moisture content of fish fed P/E(191),P/E(173)and P/E(157)were significantly higher than fish fed P/E(145),P/E(134),P/E(124)or P/E(116).Fish fed P/E(145)showed significantly higher whole body moisture content than fish fed P/E(116).Liver moisture content of fish fed P/E(191),P/E(173)and P/E(157)were significantly higher than fish fed P/E(145)P/E(134),P/E(124)and P/E(116).The lipid content of whole body and liver showed an increasing trend as the decreasing of dietary P/E ratio.Liver protein content of fish fed P/E(191)was significantly higher than fish fed P/E(145)P/E(134),P/E(124)or P/E(116)while fish fed P/E(173)and P/E(157)showed significantly higher liver protein content than fish fed P/E(116).Results indicate that a P/E ratio of 157mg/kcal was optimum for hybrid grouper juveniles(Epinephelus lanceolatus ♂× Epinephelusfuscoguttatus ♀).4 Partial replacement of fish meal(FM)with soybean meal(SBM)was examined in hybrid grouper(Epinephelus lanceolatus ♂ × Epinephelus fuscoguttatus ♀)juveniles over an 8-week growth trial.Soybean meal protein replaced 0(FM,control),10%(R10),20%(R20),30%(R30),40%(R40),50%(R50)and 60%(R60)of the FM protein in seven isoenergetic(360 kcal per 100 g dry matter)and isonitrogenous(53.5%,dry-matter basis)diets,all diets were in the same lipid level(7%;dry-matter basis).Each diet was given to triplicate groups(22 fish per group,3.58±0.05 g/fish).Juvenile fish were stocked in floating cages(L 120 cm × W 70 cm × H 50 cm)placed in indoor 6-m3 concrete ponds with continuous sea water flow(salinity:33.1 g/L).WG of hybrid grouper fed the diet with R60 was significantly lower than that of fish fed the diet with R0,R10,R20,R30 and R40,but showed no significantly difference with fish fed diet with R50.FCR of hybrid grouper fed the diet with R60 was significantly higher than those of fish fed the diet with R0,R10,R20,R30,R40 and R50 while fish fed diet R50 showed significantly higher FCR than fish fed diet R0,R10 and R20.PER of fish fed the diet with R60 was significantly lower than those of fish fed the diet with R0,R10,R20,R30,R40 and R50,R50 fed fish showed significantly lower PER than fish fed diet R0,R10,R20 and R30.DFI of fish fed the diet with R60 was significantly higher than those of fish fed the diet with R0,R10,R20,R30,R40 and R50,R50 fed fish showed significantly higher DFI than fish fed diet R0,RIO,R20 and R30.PPV of fish fed the diet with R60 was significantly higher than those of fish fed the diet with R0,R10,R20,R30,R40 and R50,R50 fed fish showed significantly higher PPV than fish fed diet R0,RIO,R20 and R30.Fish fed die R60 showed significantly lower survi-val than fish fed diet with R0,R10,R20,R30,R40 and R50.HSI of fish fed the diet with R50 and R60 was significantly lower than those fed diet with R0.The whole body lipid content of fish fed diet R60 and R50 were.significantly lower than fish fed diet R0,R10,R20,R30 and R40.The liver protein content of fish fed diet R60 was significantly higher than fish fed diet R0,R10,R20,R30 and R40,fish fed diet R50 showed significantly higher liver protein content than those of fish fed diet R0,R10,R20 and R30.The liver lipid content of fish fed R60 was significantly lower than fish fed diet R0.Results indicate that soybean meal could replace of 40%fish meal in hybrid grouper juveniles(Epinephelus lanceolatus♂× Epinephelus fuscoguttatus ♀)dietary while not affecting growth and feed utilization. |
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