Study On Utilization Of Several Animal And Plant Protein Sources For Juvenile Cobia, Rachycentron Canadum

In the studies, feeding trials were conducted to evaluate the effect of replacement of fish meal with several animal and plant protein sources such as poultry by-product meal (PBM), meat and bone meal (MBM), mixture protein source of poultry by-product meal and fermented soybean meal (PFM), and mixture protein source of meat and bone meal and fermented soybean meal (MFM) on growth performance, feed utilization and immunological indexes for junvenile cobia (Rachycentron canadum). The results can be briefly stated as follows.1. A 10-week feeding experiment was conducted to evaluate the potential use of poultry by-product meal (PBM) that could replace fish meal (FM) protein in formulated diets for junvenile cobia with an initial average weight of about 5.77±0.08 g/fish. Six isonitrogenous and isoenergetic diets (approximately 45% crude protein, and 11% crude lipid) were formulated to include 0, 15, 30, 45, 60 and 60% of FM being substituted by PBM, and the last diet supplemented with methionine (diets P0, P15, P30, P45, P60 and P60+M, respectively). The results showed that there were not significant effect on survival rate, weight gain (WG) and specific growth rate (SGR) of juvenile cobia when the PBM replce 60% FM (P>0.05), while feed efficiency (FE) and protein efficiency ratio (PER) of fish fed diets P30, P45 and P60+M were significantly higher than fish fed other diets (P<0.05). There were no significant differences observed in condition factor (CF), viserosomatic index (VSI) and intraperitoneal fat ratio (IFR) (P > 0.05), while hepatosomatic index (HSI) showed significantly higher when PBM replaced 45% FM (P<0.05). The carcass composition of fish were not observed significant differences in moisture, crude lipid, ash, calcium and phosphorus content among fish fed different trail diets (P>0.05), but the crude protein content of fish fed the control diet (P0) was significantly higher than fish fed other diets (P<0.05). All of the plasma constituents, haematological characteristics and enzyme activities were not significantly affected by the proportion of PBM protein (P>0.05) in the experimental diets, except the plasma glucose content which presented the significantly lowest value in fish fed the control diet (P0) compared with other diets (P<0.05). Results of this trail indicated that the optimum level of FM protein replacement with PBM, determined by a quadratic regression analysis on protein efficiency was 30.75%, and the crystalline methionine can improve the utilization of PBM for juvenile cobia.2. A 10-week feeding experiment was conducted to evaluate the potential use of meat and bone meal (MBM) that could replace fish meal (FM) protein in formulated diets for junvenile cobia with an initial average weight of about 5.77±0.03 g/fish. Six isonitrogenous and isoenergetic diets (approximately 45% crude protein, and 11% crude lipid) were formulated to include 0, 15, 30, 45, 60 and 60% of FM being substituted by MBM, and the last diet supplemented with methionine (diets M0, M15, M30, M45, M60 and M60+M, respectively). The results showed that there were not significant effect on survival rate (P>0.05), but the weight gain (WG), specific growth rate (SGR), feed efficiency (FE) and protein efficiency ratio (PER) were decreased with the level of FM protein replaced by MBM increased (P<0.05), while the highest replacement with methionine supplementation showed significantly better effect than without on growth. There were significant differences observed in condition factor (CF), viserosomatic index (VSI) and intraperitoneal fat ratio (IFR) (P<0.05), except hepatosomatic index (HSI) in morphological index. In whole body composition, there were no significant differences in the moisture, crude lipid, ash and phosphorus content (P>0.05), but the calcium content increased irregularly and the crude protein content reduced obviously with the increasing proportion of MBM (P<0.05). All of the plasma constituents and hematological characteristics were not significantly affected by the proportion of MBM protein in the experimental diets, except the plasma glucose content which presented the significantly highest value in fish fed the control diet (M0) compared with other diets (P<0.05). The catalase (CAT) and glutathione S-transferase (GST) showed no significant difference in enzyme activities in liver (P>0.05), but the superoxide dismutase (SOD) and glutathione peroxidase (GSH-PX) were affected by the level of the MBM replacement of FM obviously (P<0.05). Results of this trail indicated that the MBM can not replace FM partly, and the crystalline methionine can improve the utilization of MBM for juvenile cobia.3. An 8-week feeding experiment was conducted to evaluate the potential use of a mixture of poultry by-product meal (PBM) and fermented soybean meal (FSM) (PFM ,1:1 on a crude protein basis) that could replace fish meal (FM) in formulated diets for juvenile cobia with an initial average weight of about 3.81±0.12g/fish. Six isonitrogenous and isoenergetic diets (approximately 45% crude protein, and 11% crude lipid) were formulated to include 0, 20, 40, 60, 80 and100% of FM being substituted by PFM (diets PFM0, PFM20, PFM40, PFM60, PFM80 and PFM100, respectively), and all of the diets supplemented with methionine to close to the control diet, except the control diet PFM0. The results showed that survival rate was high in this study except the PFM100 (P<0.05). The final weight (FW), weight gain (WG), feed efficiency (FE) and protein efficiency ratio (PER) all declined with the increasing proportion of PFM in diet (P<0.05), but there were no significant differences in WG and specific growth rate (SGR) when less than 20% FM replaced by PFM, also in FER and PER when less than 40% (P>0.05). It showed no obviously significant difference in condition factor (CF), when replaced less than 20% FM (P>0.05), while the viserosomatic index (VSI) and hepatosomatic index (HSI) had the same trend that they had the maximum value when FM protein totally replaced by PFM (P<0.05). The intraperitoneal fat ratio (IFR) was observed significantly declined with the increasing proportion of PFM (P<0.05). The carcass composition of fish were showed significant differences in crude protein, ash, calcium and phosphorus content among fish fed different trail diets (P<0.05), but the moisture and crude protein content were not affected by the level of replacement (P>0.05). There were significant differences in cholesterin and triglyceride in plasma of fish fed different diets (P<0.05), while the plasma glucose and total protein were not affected by the different diets (P>0.05).The enzyme activities in liver were not significantly affected by the proportion of PFM in the experimental diets (P>0.05). Results of this trail indicated that the level of PFM can replace less than 31.2% FM without negative effect on the growth of juvenile cobia compared with the control diet, determined by a broken-line model analysis on special growth rate.4. An 8-week feeding experiment was conducted to evaluate the potential use of a mixture of meat and bone meal (MBM) and fermented soybean meal (FSM) (MFM, 1:1 on a crude protein basis) that could replace fish meal (FM) in formulated diets for junvenile cobia with an initial average weight of about 3.46±0.11g/fish. Six isonitrogenous and isoenergetic diets (approximately 45% crude protein, and 10% crude lipid) were formulated to include 0, 20, 40, 60, 80 and 100% of FM being substituted by MFM (diets MFM0, MFM20, MFM40, MFM60, MFM80 and MFM100, respectively), and all of the diets supplemented with methionine to close to the control diet, except the control diet MFM0 (The fish fed diet MFM100 died one after another since the forth week, and finally full of death when the trail finished, then there was no discussion about MFM100 as follows) .The results showed that survival rate has the lowest value when MFM replace 80% FM (P<0.05). The weight gain (WG) showed significantly declined with the increasing proportion of MFM in diet (P<0.05). The feed efficiency (FE), protein efficiency ratio (PER) and special growth rate (SGR) had the same trend that there were no obviously significant differences the level of MFM replace less than 20% FM (P>0.05). The condition factor (CF), viserosomatic index (VSI) and intraperitoneal fat ratio (IFR) were observed significant differences in morphological index (P<0.05), except the hepatosomatic index (HSI). The carcass composition of fish were showed significant differences in moisture, crude lipid, ash, calcium and phosphorus content among fish fed different trail diets (P<0.05), but the crude protein content were not affected by the level of replacement (P>0.05). There were significantly decreased in cholesterin with the increasing proportion of MFM (P<0.05), but the plasma glucose, triglyceride and total protein were not affected by the different diet (P>0.05). The enzyme activities in liver were not significantly affected by the proportion of MFM in the trail diets (P>0.05). Results of this trail indicated that the level of MFM can replace less than 20% FM without negative effect in growth performance for juvenile cobia.