| In this thesis,feeding trials were conducted to evaluate the effect of replacing fishmealprotein with hemoglobin powderprotein(HPP),poultry by-product meal protein(PBMP),poultry by-product meal protein and soybean meal protein(SBMP)on growth performance,feed utilization,gut and liver histology,mRNA expression levels of some feeding and immunological related genesfor hybrid grouper(Epinephelus fuscoguttatus ? ×Epinephelus lanceolatus ?)juveniles.The main contents and results of this thesis were presented as followed:1.Effects of replacing fishmeal protein by hemoglobin powder protein on growth performance,food intake,feeding-related gene expression and gut histology of hybrid grouper(Epinephelus fuscoguttatus ?× Epinephelus lanceolatus ?)× juveniles.An 8-week growth trial was conducted to evaluate effects of replacing fishmeal protein(FMP)by hemoglobin powder protein(HPP)on growth performance,food intake,feeding-related genes expression and gut histology of hybrid grouper(Epinephelus fuscoguttatus ?× Epinephelus lanceolatus ?)juveniles.Seven isoenergetic(340 kcal per 100 g dry matter),isoproteic(53.5%of dry matter)and isolipidic(7.5%of dry matter)experimental diets were formulated to replace 0%,15%,30%,45%,60%,75%and 90%FMP with HPP,being abbreviated as FMP,HPP15,HPP30,HPP45,HPP60,HPP75 and HPP90,respectively.Each experimental diet was fed to triplicate groups of 30 hybrid grouper juveniles(average initial body weight:5.27±0.05 g/fish)which were stocked into small floating cages(L 120 cm × W 70 cm × H 50 cm).Experimental cages were labeled and located in seven connective 6-m3 indoor concrete tanks(L3m×W2m×H1m)with 3 cages occurring in each tank.Fish were fed twice daily(08:00 and 16:00)to apparent satiation for 8 weeks.Water quality was monitored daily.Weight gain%(WG%),feed intake(FI),feed efficiency(FE),protein efficiency ratio(PER)and protein productive value(PPV)were significantly influenced by different dietary treatments(P<0.05).Based on the quadratic regression model and quadratic broken-line model showed that the maximum replacement level of HPP to FMP at the intercept value of WG%in diets for hybrid grouper was estimated to be 17.3%-23.3%.The relative mRNA expression levels of agouti-related protein(AgRP),neuropeptide Y(NPY)as well as orexin genes in hypothalamus of fish were significantly decreased by high HPP replacements(75%-90%)to FM protein in diets(P<0.05).For gut histology,high replacement levels of HPP to FMP significantly reduced the fold height,enterocyte height as well as microvilli height of fish foregut and midgut(P<0.05).Generally,approximately 17.3%-23.3%FM protein in diets for hybrid grouper can be replaced by HPP without negatively affecting fish growth performance and gut development.2.Effects of replacing fishmeal protein by poultry by-product meal protein on growth performance,food intake,feeding-related gene expression,gut and liver histology of hybrid grouper(Epinephelus fuscoguttatus ? × Epinephelus lanceolatus ?)juveniles.An 8-week growth trial was conducted to evaluate effects of replacing fishmeal protein(FMP)by poultry by-product meal protein(PBMP)on growth performance,food intake,feeding-related genes expression,gut and liver histology of hybrid grouper(Epinephelus fuscoguttatus ? × Epinephelus lanceolatus)juveniles.Eight isoenergetic(348 kcal per 100 g dry matter),isoproteic(53.5%of dry matter)experimental diets were formulated to replace 0%,10%,20%,30%,40%,50%,60%and 70%FMP with PBMP,being abbreviated as FMP,PBMP10,PBMP20,PBMP30,PBMP40,PBMP50,PBMP60 and PBMP70,respectively.Each experimental diet was fed to triplicate groups of 30 hybrid grouper juveniles(average initial body weight:6.0±0.05 g/fish)which were stocked into small floating cages(L 120 cm× W 70 cm × H 50 cm).Experimental cages were labeled and located in eight connective 6-m3 indoor concrete tanks(L3m×W2m×H1m)with 3 cages occurring in each tank.Fish were fed twice daily(08:00 and 16:00)to apparent satiation for 8 weeks.Water quality was monitored daily.Weight gain%(WG%),feed intake(FI),feed efficiency(FE),protein efficiency ratio(PER),protein productive value(PPV)and survival were not significantly influenced by different dietary treatments(P>0.05).Hepatosomatic index(HSI)and condition factor(CF)were significantly decreased and the intraperitoneal fat ratio(IPF)was significantly increased in fish fed high replacement levels of PBMP to FMP(P>0.05).Fish fed high PBMP had a significantly higher whole-body and muscle crude lipid contents than fish fed low PBMP(P<0.05).For gut histology,fold height(hF),enterocyte height(hE)and microvillus height(hMV)were not significantly decreased compared to fish fed the reference diet(P>0.05).Histological examinations indicated that hepatocytes with lipid vacuoles and nuclear migration were observed in fish fed high replacement levels(50%-70%)treatments.The relative mRNA expression levels of agouti-related protein(AgRP)and Proopiomelanocortin(POMC)in hypothalamus of fish were not significant affected by different experimental treatments(P>0.05).3.Effects of replacing poultry by-product meal protein by soybean meal proteinon growth performance,food intake,immunity-related genes expression,gut and liver histology of hybrid grouper juveniles.An 8-week growth trial was conducted to evaluate effects of low fishmeal protein percent diets with poultry by-product meal protein(PBMP)being replaced by different levels soybean meal protein(SBMP)on growth performance,food intake,immunity-related genes expression,gut and liver histology of hybrid grouper(Epinephelus fuscoguttatus ?×Epinephelus lanceolatus?)juveniles.Six isoenergetic(340 kcal per 100 g dry matter),isoproteic(53.5%of dry matter)and isolipidic(11.0%of dry matter)experimental diets were formulated to replace 0%and 70%FMP with different proportions of PBMP and SBMP,being abbreviated as FMP,SBMP0,SBMP7,SBMP14,SBMP21 and SBMP28,respectively.Each experimental diet was fed to triplicate groups of 15 hybrid grouper juveniles(average initial body weight:6.8±0.08 g/fish)which were stocked into small floating cages(L 120 cm× W 70 cm × H 50 cm).Experimental cages were labeled and located in six connective 6-m3 indoor concrete tanks(L 3m×W 2 m×H1m)with 3 cages occurring in each tank.Fish were fed twice daily(08:00 and 16:00)to apparent satiation for 8 weeks.Water quality was monitored daily.The results showed that growth performance andfeed utilization for fish fed all experiment diets were not significantly lower compared to fish fed the reference diet.Weight gain%(WG%),feed intake(FI),feed efficiency(FE),protein efficiency ratio(PER),protein productive value(PPV)and survival were not significantly influenced by different dietary treatments(P>0.05).The viscerosomatic index,hepatosomatic index,intraperitoneal fat ratio and condition factor as well as whole body and muscle composition were not significantly affected by the dietary treatments(P>0.05).The relative mRNA expression levels of epoxy chloropropane Kelch sample related protein-1(Keapl),nuclearfactor erythroid-2 related factor 2(Nrf2)and heat shock proteins 70(HSP70)in head kidney of fish were not significant affected by fish fed different diets(P>0.05).For gut histology,fish fed different diets were not significantly influenced in fold height(hF)and enterocyte height(hE)of fish foregut and midgut(P>0.05).However,fish fed diets which included high contents of SBMP was significantly reduced the microvilli height of fish foregut,midgut and hindgut(P<0.05).The histological examination of liver sections showed the hepatocyte volume increased and hepatocyte nuclei displacement were found when fish fed SBMP 14,SBMP21 and SBM28. |
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