| Eight feeding trials were conducted indoor culture system and outdoor cement tanks to investigate the optimal dietary protein to energy (P/E) ratio, the effects of different dietary carbohydrate levels on growth and metabolism, the nutritional value of menhaden oil, soybean oil and soybean lecithin at different ratios in practical diets and some environmental friendly feed additive application on juvenile Litopenaeus vannamei. Results of the present study are presented as follows:1. A 10-week feeding experiment was conducted to estimate the optimal dietary protein to energy (P/E) ratio for juvenile Litopenaeus vannamei (initial average weight 0.09±0.002 g). Twelve practical test diets were formulated to contain four protein levels (30%, 34%, 38% and 42%) at three lipid levels (5%, 7.5% and 10%) with P/E ratios ranging from 21.0 to 33.1 mg protein kJ-1. Each diet was randomly fed to triplicate groups of 30 shrimps per tank (260 l). The water temperature was 28.5±2°C and the salinity was 28±1, pH from 8.0-8.1 during the experimental period. The results showed that the growth was significantly affected by dietary P/E ratio (P<0.05). Shrimps fed the diets containing 30% protein and 42% protein (10% lipid) showed the poorest growth. When dietary protein levels increased from 34% to 42%, growth was slightly but not significantly higher in shrimp fed the diets with 7.5% lipid than in shrimp fed the diets with 5% and 10% lipid except for 42% protein (10% lipid). Shrimp fed the diet with 42% protein and 7.5% lipid had the highest SGR. Meanwhile shrimp fed the diet with 34% protein and 7.5% lipid showed comparable growth with that of group fed 42% protein and 7.5% lipid. However, the fish fed the diet with 34% protein and 7.5% lipid had higher protein efficiency ratio (PER), energy retention (ER) and feed efficiency ratio (FER) (P<0.05) than that of group fed 42% protein and 7.5% lipid. No significant differences on protease and amylase activity of midgut gland were found among dietary treatments. At the same protein level, serum glutamate–oxaloacetate transaminase (GOT) and glutamate–pyruviate transaminase (GPT) activities showed decreasing trends with increasing dietary lipid levels from 7.5% to 10%. The urea nitrogen, however, showed converse trend. Triglycerides (TG) and total cholesterol (TC) in the serum of shrimp increased with increasing dietary lipid level at each dietary protein level. Body lipid and energy increased with increasing dietary lipid level irrespective of dietary protein levels. Results of the present study showed that the diet containing 34% protein and 7.5% lipid with P/E of 25.1 mg protein kJ-1 is optimum for L. vannamei, and increase of dietary lipid level has not efficient protein-sparing effect.2. The effects of different dietary carbohydrate levels on growth and metabolism of juvenile Litopenaeus vannamei (initial average weight 0.17±0.00g) were evaluated using practical diets. The fishmeal and defatted soybean meal was used as main protein source, fish oil and lecithin was used as main lipid source and wheat meal as the carbohydrate. Five iso-lipidic (7% crude lipid) practical test diets were formulated to contain five carbohydrate levels (13.82, 19.41, 25.72, 31.80 and 38.20%), respective protein levels were 45.90, 42.41, 39.02, 34.41, 29.10%, respectively. Each diet was randomly fed to triplicate groups of 40 shrimps per tank (260 l) for 8 weeks. The water temperature was 28.5±2°C and the salinity was 28±1 during the experimental period. The results showed that the survival and growth was significantly affected by dietary carbohydrate levels (P<0.05). Shrimps fed the diets containing the lowest carbohydrate level (45.9% protein) showed the lowest survival, but no significant differences in survival were found among other treatments. When dietary carbohydrate level increased from 13.82 to 25.72 and protein level decreased from 45.90 to 39.02, no significant differences in growth were found. No significant differences on protease, amylase and a-glucosidase activity of intestine and muscle glycogen were found among dietary treatments. Glucose in hemolymph, protein in hemolymph and protein in intestine was significantly affected by dietary carbohydrate levels (P<0.05), and they are all the lowest concentrations in the lowest dietary carbohydrate levels (13.82%). Body protein content decreased with increasing dietary carbohydrate levels, and body lipid and body energy showed converse trend. The present results suggested that the diet containing 13.82% carbohydrate may not be enough to cover the carbohydrate requirement, and increase of dietary carbohydrate level has a little efficient protein-sparing effect.3. A 10-week feeding experiment was conducted to evaluate the nutritional value of menhaden oil (MO), soybean oil (SO) and soybean lecithin oil (SL) at different ratios (MO/SO/SL) in practical diets for juvenile Litopenaeus vannamei by determining their effects on survival, growth, blood chemistry and fatty acid composition of hepatopancreas and muscle tissue. Eight experimental isonitrogenous (crude protein content: 40.4%) and isolipidic (crude lipid content: 6.7%) diets were formulated using 3% MO(3/0/0), 3% SO(0/3/0), 3% SL(0/0/3), 1% MO + 1% SO + 1% SL (1/1/1), 1% SO + 2% SL (0/1/2), 1% MO + 2% SL (1/0/2), 2% SO + 1% SL (0/2/1) and 2% MO + 1% SL (2/0/1), respectively. Each diet was randomly fed to triplicate groups of 30 shrimps (initial weight 0.08±0.00 g) per tank (260 l). Water temperature was 28.5±2oC and salinity was 28.0±1, pH from 8.0-8.1 during the experimental period. At the end of growth trial, survivals of shrimp fed the 3% MO and 3% SO diets were lowest among dietary treatments. However, no significant differences in survival were observed among the dietary treatments containing SL. No significant difference in growth among dietary treatments was observed. The fatty acid (FA) composition of hepatopancreas and muscle tissue reflected, to a certain extent, FA composition of the test diets. Shrimp fed the 3% SL diets showed significantly higher triglyceride (TG) concentration in serum than those fed the other experiment diets (P<0.05). Total protein, total cholesterol (TC) and phospholipid (PL) concentration in serum showed increased trends when shrimp fed the diets supplemented of PL. The free fatty acids (FFA) in serum of shrimp fed the 3%SL diets showed relatively higher concentration than other treatments, but no significant differences were found among the dietary treatment. The results of the present study showed fish oil may be replaced by SL in the practical diets.4. A 10-week feeding experiment was conducted to investigate the effects of dietary molasses on the growth, digestive enzyme and body composition of juvenile Litopenaeus vannamei (initial average weight 0.08±0.00g). The basal diet was used as control, the trial diets were designed with 3 added levels of molasses which were mixed with the basal diet. The added levels of molasses were 0.22%, 0.44%, 0.66%, respectively.Each diet was randomly fed to triplicate groups of 30 shrimps (initial weight 0.08±0.00g) per tank (260 l). Water temperature was 28.5±2oC and salinity was 28.0±1, pH from 8.0-8.1 during the experimental period. The results showed that shrimps fed the diets containing molasses showed higher growth than those fed the control diet, and significantly higher growth was observed in shrimp fed dietary 4.4% molasses than in shrimp fed control diet (P<0.05). No significant differences on protease and amylase activities of midgut gland were found among dietary treatments, and significant differences on a-glucosidase activity of midgut gland wereobserved among the dietary treatment, the shrimp fed the diet with supplementation 4.4% molasses showed significant a-glucosidase activity of midgut gland than that of the control group. The present results suggested that the diet added 4.4% molasses can improve growth of shrimp.5. A 10-week feeding experiment was conducted to evaluate the effects of single and compound probiotic in outdoor cement tank (2.0×2.0×1.5 m) on growth, digestive enzyme of intestinal, bacteria of intestinal and fecal, immunity of juvenile Litopenaeus vannamei (initial average weight 0.11±0.00g). Using fish meal and defatted soybean meal as main protein sources, menhaden fish oil and soybean lecithin oil as the lipid source, wheat meal as the carbohydrate source. Shrimp were fed six different diets: control (nonsupplemented); or diet supplemented with 107 cfu g-1 Bacillus licheniformis; or with 107 cfu g-1 Bacillus subtilis; or with 107 cfu g-1 compound probiotic xiale 333; or with 0.5×107 cfu g-1 Bacillus licheniformis and 0.5×107 cfu g-1 Bacillus subtilis; or with 0.33×107 cfu g-1 xiale 333 and 0.33×107 cfu g-1 Bacillus licheniformis and 0.33×107 cfu g-1 Bacillus subtilis, respectively. Each diet was randomly fed to triplicate groups of 300 shrimps per cement tank. The water temperature was 29±3°C and the salinity was 26±3 during the experimental period. The results showed that shrimp fed compound probiotic showed relatively higher growth compared with the control diet (P<0.05), however, no significant differences in growth were observed between the single probiotic groups and the control group. The survival ranged from 76.83% to 85.67% and was not significantly different among the dietary treatments (P>0.05). Shrimp fed the diet with supplementation of probiotic could improve the activities of protease and amylase in intestine, and the activities of amylase was significantly higher in shrimp fed the compound probitic (P<0.05) than that of the control group. The probiotic could significantly (P<0.05) decrease the number of Vibrio in intestine and fecal and improve immunity of shrimp, such as: Total hemocyte counts, serum protein concentration, serum lysozyme activity, serum phenoloxidase activity (PO), serum superoxide dismutase (SOD), antioxidative capacity (T-AOC). And the compound probiotic could significantly increase (P<0.05) serum protein concentration and lysozyme activity compared with the control, however, no significant differences were observed between the single probiotic groups and the control group. The present results suggested that the diet added probiotic can improve growth and immunity of shrimp, and compound probiotic showed better effect than single one.6. A 8-week feeding experiment was conducted to evaluate the effects of two different Cysteamine addition way on growth, digestive enzyme and immune of juvenile Litopenaeus vannamei (initial average weight 0.27±0.00g). The basal diet was used as control, the trial diets were designed with 2 added levels of Cysteamine which were mixed with the basal diet, one added level is 0.01%, the other added level is interval addition Cysteamine (fed 0.05% Cysteamine one day every five days), and 5mg/kg flavomycin addition as the other control on growth. The water temperature was 29±3°C and the salinity was 28±1 during the experimental period. The results showed that shrimps fed the diets containing cystermine and flavomycin showed higher growth than those fed the control diet (P<0.05), Compared with the flavomycin addition group, interval addition cysteamine group showed the higher growth (P<0.05). No significant differences on protease and amylase activities of midgut gland were found among dietary treatments. Glucose content and GH activities in the serum of shrimp fed Cysteamine was significantly higher (P<0.05) than that of the control group, and total cholesterol (TC) and urea nitrogen in the serum of shrimp fed Cysteamine was significantly lower (P<0.05) than that of the control group. Compared with the contrast group, interval addition Cysteamine group improved significantly (P<0.05) serum protein concentration. No significant differences on antioxidant activities of serum were found among dietary treatments. The present results suggested that the diet added cysteamine can improve growth, interval addition cysteamine showed better growth effect than flavomycin.7. A 10-week feeding experiment was conducted to evaluate the effects of xylooligo saccharides (XOS) on growth, digestive enzyme, bacteria of intestinal and immune of juvenile Litopenaeus vannamei (initial average weight 0.27±0.00g). The basal diet was used as control, the trial diets were designed with 2 added levels of XOS which were mixed with the basal diet. The added levels of XOS were 0.02%, 0.04%, respectively, and 5mg/kg flavomycin addition as the other control on growth. The water temperature was 29±3°C and the salinity was 28±1 during the experimental period. The results showed that shrimps fed the diets containing 0.02% XOS and flavomycin showed higher growth than those fed the control diet (P<0.05). Higher activities of protease and amylase of midgut gland and protease of intestinal were observed when shrimp fed the diets with 0.02% XOS than that of the control group (P<0.05). The XOS additive could significantly (P<0.05) decrease the number of total bacteria counts and Vibrio counts of intestinal compared with control, and 0.02% XOS additive could significantly (P<0.05) increase the number of bifidobacteria bacteria counts of intestinal compared with control. Total cholesterol (TC) in the serum of shrimp fed XOS was significantly lower (P<0.05) than that of the control group. The XOS additive could significantly (P<0.05) decrease the body lipid. Shrimp fed the diets with 0.02% XOS shower higher hemocytes, phenoloxidase (PO) and total antioxidative capacity (T-AOC) activities than those fed control diets. The present results suggested that the diet added 0.02% XOS can improve growth and immune of shrimp.8. A 8-week feeding experiment was conducted to evaluate the effects and the interactions of compound probiotics and oligosaccharides on growth, microbial population and serum biochemical index in juvenile litopenaeus vannamei (initial average weight 0.56±0.00g). Using fish meal and defatted soybean meal as main protein sources, menhaden fish oil and soybean lecithin oil as the lipid source, wheat meal as the carbohydrate source. Shrimp were fed eight different diets: control (nonsupplemented); or diet supplemented with 0.1%MOS; or with 0.4% FOS; or with 107 cfu g-1 compound probiotic; or with 0.05% MOS and 0.2% FOS; or with 107 cfu g-1 compound probiotic and 0.05% MOS; or with 107 cfu g-1 compound probiotic and 0.2% FOS; or with 107 cfu g-1 compound probiotic and 0.2% FOS and 0.05% FOS, respectively. Each diet was randomly fed to triplicate groups of 35 shrimps per tank (260 l). The water temperature was 29±3°C and the salinity was 28±1 during the experimental period. The results showed that shrimp fed the trial diets showed relatively higher growth compared with the shrimp fed control diet except for 0.1% MOS group at first 28 day (P<0.05), and the combinations of probiotics with oligosaccharides groups showed higher growth than single probiotics and oligosaccharides groups. However, no significant differences in growth were observed between the trial groups and the control group from 28 day to 56 day. The probiotics and oligosaccharides significantly (P<0.05) decrease the number of Vibrio in intestine and fecal and significantly (P<0.05) increase total bacteria counts fecal. The combinations of probiotics with oligosaccharides groups had fewer the number of Vibrio in intestine than single probiotics and oligosaccharides groups. The oligosaccharides and the combinations of probiotics with oligosaccharides could significantly (P<0.05) decrease serum total cholesterol (TC) content, and the probiotics and the combinations of probiotics and oligosaccharides significantly increase (P<0.05) content of serum glucose of shrimp. In conclusion, the addition of probiotics and oligosaccharides alone or combined in the diet improved microbial population status and growth of shrimp at only first 4 week feeding. |
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