| In this study, we selected a representative fish species golden pompano (Trachinotus ovatus) and feed ingredients (soy protein), combined with using gamma ray irradiation passivation technique of anti-nutritional factors, functional micronutrients supplementary and balanced feed formulation to comparative study the limitation causes of fish meal replaced by cheap plant protein. The goal of this study was to explore new ways for fish meal replacement, and to provide scientific basis for development of high nutrition, low pollution, low-cost feed in mariculture. The main results are shown as follows:(1) A six-week feeding trial was conducted to examine the effect of feeding frequency on growth, feed utilization efficiency, body composition and waste output of juvenile golden pompano Trachinotus ovatus reared in net pens. Fish (10.3±0.5g) were either fed a formulated diet containing48.4%crude protein and5.7%crude lipid at0.5,1,2,3or4meals d-1or fed a raw fish feed at2meals d-1as a control. The weight gain (WG) increased with increasing feeding frequency from0.5to3meals d-1(P<0.05), but did not significantly change with the further increase in feeding frequency from3to4meals d"1(P>0.05). The feed intake (FI) was lower in fish fed at0.5or1meal d-1than in fish fed at2,3or4meals d"1(P<0.05). No significant differences were found in the feed conversion ratio (FCR), nitrogen retention efficiency (NRE), condition factor (CF), nitrogen wastes output (NWO) and phosphorus wastes output (PWO) between fish fed at1,2,3or4meals d"1(P>0.05), whereas no significant difference was found in the phosphorus retention efficiency (PRE) among the feeding treatments (P>0.05). The body lipid content increased, whereas the contents of moisture and ash decreased, with the increase of feeding frequency (P<0.05). At the same feeding frequency, fish fed the formulated diet exhibited lower FI, FCR, hepatosomatic index, body moisture content, NWO and PWO, but higher NRE, PRE, body lipid content and body phosphorus content than those of fish fed the raw fish feed (P<0.05). These results suggest that the formulated diet can satisfy nutrient requirements of juvenile golden pompano reared in net pens, and the suitable feeding frequency is3meals d"1.(2) A5-week feeding trial was conducted to assess the potential of using gamma ray irradiated soybean meal as a fish meal substitute in diets for juvenile golden pompano (Trachinotus ovatus). A diet containing32%fish meal was used as a reference (C), and75%of the fish meal in diet C was replaced by soybean meal that either received no gamma ray irradiation (R0) or was irradiated with gamma ray at a dose of5(R5),10(R10),15(R15),30(R30) or60(R60) kGy, respectively. The weight gain was higher in fish fed diets R5, R10, R15and R30than in fish fed diet RO (P<0.05), whereas no significant difference was found in weight gain between fish fed diets R0and R60or between fish fed diets R5, R10, R15, R30and R60(P>0.05). The feed intake was higher in fish fed diets R15, R30and R60than in fish fed diets R0, R5and R10(P<0.05). No significant differences were found in feed conversion ratio (FCR), nitrogen retention efficiency (NRE), condition factor, hepatosomatic index (HSI), body composition, waste outputs of nitrogen (NWO) and phosphorus (PWO) between fish fed the diets with non-irradiated soybean meal or irradiated soybean meal as the fish meal substitute (P>0.05). The weight gain was higher in fish fed diet C than in fish fed diet R15(P<0.05). No significant differences were found in feed intake, FCR, NRE, NWO, condition factor, HSI, body composition between fish fed diets C and R15(P>0.05). Proteins of heavy molecular in soybean meal were degraded, whereas contents of proteins of light molecular or peptides increased with the increase of the irradiation dose. This study reveals that gamma ray irradiation at a dose of5to15kGy can significantly improve the level of fish meal replacement by soybean meal in diets for golden pompano.(3) Two7-week feeding trials were conducted to evaluate the capacity of golden pompano (Trachinotus ovatus) to use soy protein concentrate (SPC) as a dietary fish meal substitute. In trial I, fish were fed with a control diet (C) containing40%fish meal and other four diets in which the fish meal in diet C was replaced by SPC at20(R20),40(R40),60(R60) and80%(R80). In trial II, a3×2design was used, and40and80%of the fish meal in diet C were replaced by SPC, with or without0.5%taurine supplementation (six diets, C+T, R40+T, R80+T, C, R40and R80, were formulated). In trial I, no significant difference was found in the feed intake between the feeding treatments. The weight gain and nitrogen retention efficiency (NRE) decreased, whereas the feed conversion ratio (FCR) and phosphorus retention efficiency (PRE) increased, with decreasing dietary levels of fish meal (P<0.05). No significant differences were found in the weight gain, FCR and NRE between fish fed diets C and R20(P>0.05), whereas fish fed diets C and R20had higher weight gain than those fed diets R40, R60and R80(P<0.05). In trial II, no significant differences were found in the feed intake, weight gain, FCR, NRE and PRE between fish fed diets C+T and C (P>0.05). No significant differences were found in the feed intake, weight gain and NRE between fish fed diets R40and R40+T or between fish fed diets R80and R80+T (P>0.05). At the end of trial II, no significant differences were found in the condition factor, hepatosomatic index and body composition between fish fed diets C and C+T, or between fish diets R40and R40+T, or between fish fed diets R80and R80+T (P>0.05), except that fish fed diet R40had lower body protein content than that of fish fed diet R40+T (P<0.05). The present study reveals that taurine supplementation can elevate fish meal replacement level by SPC in the golden pompano diets. Fish meal can be reduced from40%to32%if fish meal is substituted by SPC without taurine supplementation, and can be further reduced to24%if fish meal is substituted by SPC with0.5%taurine supplementation.A7-week feeding trial was conducted to evaluate the effect of selenium-yeast (Se-yeast) supplementation on replacing fish meal with soy protein concentrate (SPC) in diets for golden pompano (Trachinotus ovatus). A reference diet (C) was formulated to contain40%fish meal, and40and80%of the fish meal in diet C were replaced by SPC, with or without1%Se-yeast supplementation (four diets, R40+Se, R80+Se, R40and R80were formulated). No significant difference was found in the feed intake (FI), feed conversion ratio (FCR) and nitrogen retention efficiency (NRE) between fish fed diets R40+Se, R80+Se, R40and R80(P>0.05). The weight gain decreased, whereas the phosphorus retention efficiency (PRE) increased, with decreasing dietary levels of fish meal, regardless of Se-yeast supplementation (P<0.05). No significant differences were found in the weight gain, FCR and NRE between fish fed diets C and R40+Se (P>0.05), whereas fish fed diet C had higher weight gain than fish fed diet R40(P<0.05). At the end of the feeding trial, no significant differences were found in the condition factor, hepatosomatic index and body composition between fish fed diets R40, R80, R40+Se and R80+Se (P>0.05). The present study reveals that fish meal in the golden pompano diets can be reduced from40%to24%if fish meal is substituted by SPC with1%Se-yeast supplementation, and more fish meal are required if fish meal is substituted by SPC without Se-yeast supplementation.A7-week feeding trial was conducted to evaluate the capacity of golden pompano (Trachinotus ovatus) in utilizing soy protein concentrate (SPC) as a dietary fish meal substitute with a supplementation of taurine (T), Se-yeast (Se) or in combination (TSe). In the trial, fish were fed with a control diet (C) containing40%fish meal, and40and80%of the fish meal in diet C were replaced by SPC, with or without T, Se, or TSe (eight diets, R40, R80, R40+T, R80+T, R40+Se, R80+Se, R40+TSe and R80+TSe, were formulated). The weight gain and waste outputs of phosphorus (PWO) was dependent on fish meal level and the supplementation of taurine, Se-yeast or in combination, while feed intake (FI), hepatosomatic index (HSI) and body lipid content was significantly affected by the fish meal level (P<0.05). No significant effect of fish meal level and the supplementation of taurine, Se-yeast or in combination was found in feed conversion ratio (FCR), nitrogen retention efficiency (NRE), phosphorus retention efficiency (PRE), condition factor, body composition (crude protein, ash and phosphorus)(P>0.05). The weight gain was higher in fish fed diet R80+TSe than in fish fed diet R80, R80+T and R80+Se, while waste outputs of nitrogen (NWO) and PWO in fish fed diet R80+TSe were significantly lower than in fish fed diet R80(P<0.05). No significant differences were found in FI, FCR and NRE among them (P>0.05). The present study reveals that fish meal cannot be reduced to8%if fish meal is substituted by SPC with in combination of0.5%taurine and1%Se-yeast supplementary. Taurine and Se-yeast supplementation can significantly enhance growth performance in8%fish meal diet with reducing waste output. Taurine and Se-yeast may be a limited factor in utilization of SPC.(4) A5-week feeding trial was conducted to examine the effect of γ-ray irradiation on the inclusion of soybean meal (SBM) and soy protein concentrate (SPC) in the diets of juvenile golden pompano (Trachinotus ovatus). The fish diet containing32%fish meal was used as a reference, and other four diets were formulated with75%of the fish meal replaced by SBM, SPC, SBM irradiated with γ-ray at30kGy (SBM30), or SPC irradiated with γ-ray at30kGy (SPC30). The weight gain was higher in fish fed SBM30and SPC30than in fish fed SBM and SPC respectively, whereas fish consumed more SBM30than SBM, SPC or SPC30(P<0.05). No significant differences were found in feed conversion ratio (FCR), nitrogen retention efficiency (NRE), phosphorus retention efficiency (PRE), condition factor (CF), hepatosomatic index (HSI), body composition, waste outputs of nitrogen (NWO) and phosphorus (PWO) between fish fed diets SBM and SBM30or between fish fed diets SPC and SPC30(P>0.05). The weight gain and PWO were higher, but the FCR, PRE, NWO and body phosphorus were lower in fish fed the reference diet than those in fish fed SBM30(P<0.05). No significant differences were found in the feed intake, NRE, CF, HSI, body compositions between fish fed reference diet and SBM30(P>0.05). Macromolecular proteins in SBM and SPC were degraded, whereas contents of amino acids and peptides were increased by y-irradiation. This study reveals that y-ray irradiation can significantly improve the performance of SBM and SPC with possible inactivation of some anti-nutritional factors, such as protease inhibitor, lectins and allergens.(5) A5-week feeding trial was conducted to examine the effect of y-ray irradiation treatment and compound micronutrients (A) on the inclusion of soybean meal (SBM) in the diets of juvenile golden pompano Trachinotus ovatus. The fish diet containing32%fish meal was used as a reference, and other three diets were formulated with75%of the fish meal replaced by SBM or SBM irradiated with y-ray at60kGy (SBM60), or SBM60with0.6%compound micronutrients supplementary (SBM60+A). The weight gain, feed intake (FI) and phosphorus retention efficiency (PRE) were higher in fish fed SBM60+A and SBM60than in fish fed SBM, whereas waste outputs of phosphorus (PWO) was lower in fish fed SBM60+A and SBM60than in fish fed SBM (P<0.05). No significant differences were found in feed conversion ratio (FCR), nitrogen retention efficiency (NRE), waste outputs of nitrogen (NWO), condition factor (CF), hepatosomatic index (HSI), body composition (moisture, crude lipid, crude protein and ash) among them (P>0.05). Compared with diet C, fish fed SBM60+A exhibited higher FI, FCR, PRE and NWO, but lower PWO (P<0.05). No significant differences were found in weight gain and NRE between fish fed diet C and SBM60+A (P>0.05). The present study reveals that fish meal can be reduced from32%to8%if fish meal is substituted by SBM with γ-ray irradiation treatment and0.6%compound micronutrients supplementatary. The feed utilization was low even using irradiation SBM with0.6%compound micronutrients supplementatary. (6) A7-week feeding trial was conducted to examine the effect of y-ray irradiation treatment and in combination of0.6%compound micronutrients (A) and0.4%compound premix (B) supplementary on the inclusion of soybean meal (SBM) in the diets of juvenile golden pompano Trachinotus ovatus. The fish diet containing32%fish meal was used as a reference, and other four diets were formulated with50%of the fish meal replaced by SBM (R) or SBM irradiated with y-ray at15kGy (R15), or R15with0.6%compound micronutrients supplementary (R15+A), or SBM15with in combination of0.6%compound micronutrients (A) and0.4%compound premix (B) supplementary (R15+A+B). Fish fed raw fish (RF) used as another reference. The weight gain (WG) and nitrogen retention efficiency (NRE) were higher in fish fed R15+A+B than in fish fed R, R15and R15+A, whereas feed intake (FI), feed conversion ratio (FCR), waste outputs of nitrogen (NWO) and phosphorus (PWO) were lower in fish fed R15+A+B than in fish fed R, R15and R15+A (P<0.05). Fish fed diet R15+A+B exhibited higher WG, NRE and phosphorus retention efficiency (PRE), but lower FI, FCR, NWO and PWO, than fish fed diet C and RF (P<0.05). No significant differences were found in hepatosomatic index (HSI) and body composition (moisture, crude protein, crude lipid, ash and phosphorus) between fish fed diet C, RF and R15+A+B (P>0.05). The present study reveals that fish meal can be reduced from32%to16%if fish meal is substituted by SBM with y-ray irradiation treatment and in combination of0.6%compound micronutrients and0.4%compound premix supplementary. This way can reduce waste output of golden pompano reared in net pens with improving growth performance and feed utilization.The results show that the existence of resistance protein and the deficiency of compound micronutrient is an important reason for limiting soybean protein ingredients as fish meal substitute in golden pompano diet. Gamma irradiation and in combination of0.6%compound micronutrient (A) and0.4%compound premix (B) can significantly improve the potential of use soybean protein ingredients as fish meal subustitute in golden pompano diets with reduction of fish meal level and aquaculture waste output. |
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