| As fish meal is the major source of animal protein in aquaculture diet, the increasing demand for fish meal by aquaculture industry makes fish meal an increasingly expensive and limiting commodity. As a result, it is essential to explore other suitable plant proteins to replace fish meal in diet for sustaining aquaculture development. Cottonseed meal (CSM) is a common source of plant protein that has been used to feed terrestrial and aquatic animals. Considering the defects caused by cottonseed meal, such as amino acid imbalancement and palatability decreasement, it is necessary to add amino acid and other substance to improve the utilization of plant protein sources. In the present study, an8-week feeding trial has been conducted to investigate the effects of dietary methionine supplementation in cottonseed meal-based diets on the growth performance, digestibility and antioxidant ability of juvenile Chinese mitten crab, Eriocheir sinensis. Then under the best methionine supplementation studied above, the effects of replacement of methionine with betaine/Tautine in practical diets for juvenile Chinese mitten crab, Eriocheir sinensis were investigated. The results can be briefly summarized as follows:1. Effects of dietary methionine supplementation on feeding, growth and antioxidant ability of juvenile Chinese mitten crab, Eriocheir sinensisThis study was conducted to evaluate the effects of dietary methionine supplementation in cottonseed meal-based diets on the growth performance, digestibility and antioxidant ability of juvenile Chinese mitten crab, Eriocheir sinensis, Five diets were formulated with a basic diet, in which cottonseed meal accounted for40%, supplemented with0.00%,0.14%,0.28%,0.42%,0.56%methionine, respectively, another diet was full fish meal-based (fish meal accounted for64.4%) which was served as the control. Each diet was fed to juvenile E. sinensis [(0.39±0.02) g] of five replicates for6weeks. The results showed that weight gain, specific growth rate and feed conversion ratio of crabs fed0.42%Met diet did not differed from those of the control crabs (P>0.05). Crabs fed diets with0.28%Met and0.42%Met exhibited higher food intake and protein deposition rate than those fed diets with0.00%Met,0.14%Met and0.56%Met (P<0.05). There were no significant differences in whole body moisture, lipid and ash among all treatments (P>0.05). However, compared with the0.00%Met group, the crude protein contents in crab fed diets supplemented with methionine were significantly higher (P<0.05). Dry matter, protein, lipid digestibility and trypsin activity of crabs fed diet with0.42%Met did not differ from those of the control (P>0.05). No differences were found in malondiadehyde content, serum superoxide dismutase and glutathione peroxidase activity of crabs fed the control diet and diets with0.28%Met,0.42%Met and0.56%Met (P>0.05). The results suggest that0.42%Met added to the diet (cottonseed meal accounted for40%) can significantly accelerate the growth performance, digestibility and antioxidant ability of juvenile E. sinensis.2. Partial or total replacement of methionine with betaine in practical diets for juvenile Chinese mitten crab, Eriocheir sinensis:Effects on feeding, growth and serum biochemical indicesThis study was conducted to evaluate the effects of partial or total replacement of methionine with betaine in practical diets on the growth performance, digestibility and serum biochemical indices of juvenile Chinese mitten crab, Eriocheir sinensis, Five diets were formulated with a basic diet, in which cottonseed meal accounted for40%, control group was supplemented with0.4%methionine, whereas trial groups replace betaine for25%,50%,75%and100%methionine, respectively. Each diet was fed to juvenile E. sinensis [(0.28±0.01) g] of five replicates for8weeks. The results showed that weight gain, specific growth rate and food intake of crabs fed50%S diet were significantly higher than those of the control crabs (P<0.05). Crabs fed diets with50%S exhibited lower feed conversion ratio than those fed with other diets (P<0.05). There were no significant differences in whole body moisture, crude protein, crude lipid and ash (P>0.05) among all treatments. However, compared with the control group, the hepatic lipid contents in crab fed50%S,75%S diets were significantly lower (P<0.05). The activity of trypsinase, amylase and lipase in intestine of crabs fed diet with50%S diets were significant higher than those of the control (P<0.05). Total cholesterol, triglycerides and low density lipoprotein cholesterol in serum of crabs fed the trial diets were significantly higher than those of the control crabs (P<0.05), however, high density lipoprotein cholesterol in serum of crabs fed the trial diets were significantly lower than those of the control crabs (P<0.05). The results suggest that replacing betaine for50%methionine in practical diets (cottonseed meal accounted for40%) can significantly improve the growth performance, digestibility and serum biochemical indices of juvenile E. sinensis, at the same time, the content of methionine in practical diets should not be under0.56%.3. Partial or total replacement of methionine with taurine in practical diets for juvenile Chinese mitten crab, Eriocheir sinensis:Effects on feeding, growth and antioxidant abilityAn8-week feeding trial has been conducted to investigate the effects of partial or total replacement of methionine with betaine in practical diets on the growth performance, digestibility and immunity of juvenile Chinese mitten crab, Eriocheir sinensis, Five diets were formulated with a basic diet, in which cottonseed meal accounted for40%, control group was supplemented with0.4%methionine, whereas trial groups replace tautine for25%,50%,75%and100%methionine, respectively. Each diet was fed to juvenile E. sinensis [(0.28±0.01) g] of five replicates. The results showed that weight gain, specific growth rate and food intake of crabs fed25%S diet were significantly higher than those of the control crabs (P<0.05). Crabs fed diets with25%taurine exhibited lower feed conversion ratio. There were no significant differences in whole body moisture, crude protein, crude lipid and ash (P>0.05) among all treatments. However, compared with the control group, the hepatic lipid contents in crab fed control diet were significantly higher than other groups (P<0.05). The activities of lipase in intestine of crabs fed diet with control diet were significant lower than those of other groups (P<0.05). No differences were found in malondiadehyde content, serum superoxide dismutase and phenoloxidase activity of crabs fed different diets (P>0.05). The results suggest that replacing tautine for25%methionine in practical diets (cottonseed meal accounted for40%) can significantly improve the growth performance, digestibility and antioxidant ability of juvenile E. sinensis. |
PDF Full Text Request