Study On The Effect Of Fishmeal Replacement With Compound Proteins In The Diet Of Turbot Juvenile (Scophthalmus Maximus L.)

Five feeding trials were conducted to investigate the effect of fishmeal replacement with alternative proteins on performance of turbot juvenile （Scophthalmus maximus L）. Firstly, apparent digestibility coefficients of several plant and animal proteins were detected. Secondly, the application of two new protein sources （silkworm meal and silkworm chrysalis meal） into the feed of turbot was also investigated. At the same time, plant compound protein, animal compound protein, plant and animal compound protein were mixed with the sole protein mentioned above, and then their effects to substitute fishmeal were investigated. The results were summarized as follows:1.Apparent digestibility coefficients of dry matter （DM）, crude protein （CP）. gross energy （GE）, and amino acids in Peruvian super red fishmeal （FM）, peanut meal （PM）, corn gluten meal （CGM）. dehulled solvent extracted soybean meal （SBM）, wheat gluten （WG）. Australian beef meat and bone meal （MBM）. spray-dried pork hemoglobin meal （SDHM） and American pet-food grade poultry byproduct meal （PBM） were determined for juvenile turbot. A reference diet （RF） and test diets （consisting of 70% RF diet and 30% of the test ingredients） were used with 0.1% Y₂O₃ as an external indicator. The juvenile turbot. averaging 6 g. was stocked in 200-L fiberglass tanks at a density of 40 fishes per tank for 5 weeks. Feces were collected from triplicate groups of fish using stripping technique. The apparent dry matter digestibility of animal proteins for juvenile turbot was 84.40% for FM. and ranged from 30.34% to 65.98% for the others. The highest apparent dry matter digestibility of plant proteins examined for juvenile turbot was 70.20% for WG. and ranged from 25.63% to 33.94% for the others. Apparent protein and energy digestibilities were ranged from 73.93% to 87.68% and 61.76% to 96.46% respectively for animal products; 48.50% to 85.16% and 36.08% to 85.85% respectively for plant products. Amino acid availability nearly reflected protein digestibility.Results indicated that turbot utilized high-protein feedstuffs better than high-carbohydrate or high-fiber feedstuffs.2. A trial on turbot juveniles was undertaken to evaluate the effect of replacing dietary fishmeal （FM） with a complementary mixture of plant proteins （PP） and animal protein （AP） consisting of soybean meal （SBM）, wheat gluten meal （WGM）. peanut meal（PM）. corn gluten meal （CGM） and silkworm source. Six isonitrogenous （crude protein 50%） and isolipidic （crude lipid 12%） practical diets were designed. The whole fishmeal diet was regarded as the control group. Five other diets were formulated to replace fishmeal protein at 40% by PP、PP+5% silkworm meal （PP+5C）、PP+5% silkworm meal （PP+10C）、PP+5% silkworm chrysalis meal （PP+5Y）、PP+10% silkworm chrysalis meal （PP+10Y）, separately. Crystalline amino acids were added to keep the balance of essential amino acids at each replacement level. Diets were fed to juvenile turbot （initial body weight 6.60±0.14g fish-1） in triplicate for 90 days. Results showed that fish fed PP and PP+10C groups showed no significant difference compared with the control group in final individual body weight （FBW）, specific growth rates （SGR）, Daily feed intake （DFI）, feed efficiency rate （FER） and protein efficiency rate （PER） （P>0.05）. FBW、SGR and DFI in PP+5C were significant higher （P<0.05）, but FER and PER showed no significant difference compared with the control group. Even though PP+5Ygroup had the same FBW and SGR with the control group, PER and FER in this group were significant reduced, and DFI was significant increased compared with control group （P<0.05）. FBW, SGR. FER and PER in PP+10Y group were significant reduced compared with control group （P<0.05） except for DFI. None of the diets affected whole body composition, hepatosomatic index （HSI）, viscerosomatic index （VSI） and condition factor （CF） （P>0.05）. In conclusion, substitution of 40% of FM protein in the diet of turbot was successful; appropriate supplement of silkworm meal may have a beneficial effect to the growth but silkworm chrysalis meal did not have this effect.3. A trial on turbot juveniles was undertaken to evaluate the effect of replacing fishmeal （FM） with plant compound protein （PCP） consisting of peanut meal （PM）, corn gluten meal （CGM）. dehulled solvent extracted soybean meal （SBM）. wheat gluten （WG）. Five isonitrogenous （50%） and isoenergetic (20MJ kg^-1) practical diets were designed. The whole fishmeal diet （Diet 1） was regarded as the control. Then fishmeal was replaced at 30%（diet 2）.45%（diet 3）.60%（diet 4） by PCP separately. Lys and Met were added to diet 4 to keep the balance of essential amino acids with the control, which was regard as diet 5. Diets were fed to juvenile turbot. averaging 7.35 g, in triplicate for 10 weeks. The results showed that even through FER and PER reduced, DFI increased with the replacement level increasing （P<0.05）. growth performance of fish fed all the groups had no significant difference compared with the control group（P>0.05）:ADCs of dry matter and ADCs of protein had the same trend, when the replacement level reached 60%. they both significant reduced （P<0.05）. None of the diets affected whole body composition. HSI, VSI. CF and Serum indexes （P>0.05） at the end of the experiment. In conclusion, substitution of 60% of FM with PCP in the diet of turbot had no effect on growth performance, whole body composition and Serum indexes, but it would reduce the feed utilization efficiency and protein utilization efficiency.4. A trial on turbot juveniles was undertaken to evaluate the effect of replacing fishmeal （FM） with animal compound protein （ACP） consisting of meat and bone meal （MBM）, spray-dried haemoglobin meal （SDHM）, poultry byproduct meal （PBM） and pupa peptide protein meal （PPM）. Five isonitrogenous （50%） and isoenergetic (20MJ kg^-1) practical diets were designed. The whole fishmeal diet （Diet 1） was regarded as the control. Then fishmeal was replaced at 30%（diet 2）,45%（diet 3）, 60%（diet 4） by ACP separately. Lys and Met were added to diet 4 to keep the balance of essential amino acids with the control, which was regard as diet 5. Diets were fed to juvenile turbot. averaging 7.35 g. in triplicate for 10 weeks. The results showed that fish fed the test groups had significant lower SGR compared with the control group except for diet 2 （P<0.05）. Fish fed the diet 4 and 5 showed significant increased DFI compared with the control （P<0.05）. FER and PER of the fish showed similar trend to SGR. ADCs of dry matter were significant lower for the fish fed test diets except for fish fed diet 2 （P<0.05）. ADCs of protein were negatively affected when the substitute level were above 45%（P<0.05）. None of the diets affected whole body composition, HSI, VSI, CF and Serum indexes （P>0.05） at the end of the experiment. In conclusion, substitution of 30% of FM with ACP in the diet of turbot was successful.5. A trial on turbot juveniles was undertaken to evaluate the effect of replacing fishmeal （FM） with plant and animal compound protein （PAP） consisting of Peanut meal （PM）, Corn gluten meal （CGM）. Dehulled solvent extracted soybean meal （SBM）, Wheat gluten （WG）. Australian beef meat and bone meal （MBM）, Spray-dried pork hemoglobin meal （SDHM）. American pet-food grade poultry byproduct meal （PBM） and pupa peptide protein meal （PPM）. Six isonitrogenous （50%） and isoenergetic (20MJ kg^-1) practical diets were designed. The whole fishmeal diet （Diet 1） was regarded as the control. Then fishmeal was replaced at 30%（diet 2）. 40%（diet 3）,50%（diet 4）,60%（diet 5）,70%（diet 6） by PAP separately. Lys and Met were added to the diets to keep the balance of essential amino acids with the control. Diets were fed to juvenile turbot （8.37±0.02g） in quadruplicate for 56 days. The results showed that FBW and SGR of fish fed the test groups were not significant different compared with the control group except for diet 6, which were significant lower compared with the control group （P<0.05）. DFI and FER of fish fed the test groups were all significant different compared with the control group except for diet 2 （P<0.05）. None of the diets affected ADCs of dry matter and ADCs of protein at the end of the experiment （P>0.05）. None of the diets affected whole body composition, HSI, VSI, CF and Serum indexes （P>0.05） too at the end of the experiment. As for intestinal histology,70% levels of fish meal protein replaced by PAP significantly lowered the villi length and quantities, and lamina propria was widened at the same time. In conclusion, substitution of 60% of FM with PAP in the diet of turbot was successful.