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1.
Effects of dietary supplementation of β-glucans and nucleotides on growth, survival and immune responses of the Pacific white shrimp (Litopenaeus vannamei) at a low salinity (5 ppt) were evaluated during a 30 d feeding trial. Final mean weight of shrimp fed nucleotides at 0.5%?was highest and significantly different from those fed the basal diet or diets supplemented with β-glucans. Survival was significantly higher for shrimp fed the diet with 0.2%?β-glucans compared to all other diets and was lowest for shrimp fed the basal diet. Shrimp fed diets containing β-glucans and nucleotides had generally better immune responses than shrimp fed the basal diet with higher total hemocyte count (THC) recorded for shrimp fed 0.2%?β-glucans followed by those fed 0.2%?nucleotides. Shrimp fed diets with 0.2%?and 0.5%?nucleotides and 0.2%?β-glucans had significantly higher respiratory burst values than shrimp fed the basal diet. These results indicated that dietary supplementation of either nucleotides or β-glucans has beneficial effects in improving shrimp performance when cultured at low salinity.  相似文献   

2.
A 35‐day feeding trial was conducted to evaluate growth, bacterial populations of the gastrointestinal tract (GIT) and immune responses of Litopenaeus vannamei fed diets containing the commercial prebiotic Previda®. Diets were formulated to contain Previda® at 0, 0.2, 0.5, 1.0 or 1.6 g kg?1 by weight. At the end of the study, differences in weight gain and survival among treatments were not significant (P > 0.05), but denaturing gradient gel electrophoresis analysis revealed that the microbial communities in the GIT changed significantly with the inclusion of dietary Previda® at different levels. Previda® was therefore able to selectively modify the microbial communities in the shrimp's GIT. Although individual bacterial species were not identified, enteric populations in shrimp fed the prebiotic at similar levels of inclusion were genetically similar. In addition, shrimp fed Previda® at 1.6 g kg?1 responded significantly (P < 0.05) better immunologically with respect to hemocyte phagocytic capacity, haemolymph protein, hyaline cell counts and haemolymph glucose compared with shrimp fed the basal diet. Although shrimp were not exposed to virulent pathogens in this study, the observed upregulation of some of imm‐une responses upon prebiotic supplementation indicates that an improved outcome of such challenges may be anticipated in Previda®‐fed shrimp under commercial conditions.  相似文献   

3.
This study was conducted to evaluate the effects of fulvic acid (0, 0.3, 0.6, 0.9, and 1.2%) as feed additive on growth, feed utilization, antioxidant ability, and HSP70 in hemolymph and hepatopancreas of juvenile white shrimp Litopenaeus vannamei (average weight 2.5 g) reared under experiment conditions. Shrimp were stocked at a density of 625 shrimps m?3 for 60 days in net cages submerged in recirculating tanks. At the end of the experiment, specific growth rates and survival rates of shrimp in treatment groups fed with 0.6, 0.9, and 1.2% fulvic acid were higher compared to that of the control group. Shrimp fed 0.6, 0.9, and 1.2% fulvic acid had significantly lower feed conversion rates than those fed control diet. The optimum dietary fulvic acid requirement for juvenile shrimp based on weight gain was 0.897%. Furthermore, superoxide dismutase activity and peroxidase activity increased significantly, while malonaldehyde content decreased in the hemolymph and hepatopancreas of shrimp fed 0.9 and 1.2% dietary fulvic acid. Glutathione content increased obviously in hemolymph of shrimp fed 0.6, 0.9, and 1.2% fulvic acid. In hepatopancreas, glutathione content was significantly higher in shrimp supplemented with 1.2% fulvic acid. HSP70 decreased obviously in hemolymph of shrimp fed 0.9 and 1.2% fulvic acid, while shrimp fed with 0.6 and 0.9% fulvic acid showed lower HSP70 level in hepatopancreas. The results of this study demonstrated that dietary fulvic acid could improve survival rates, growth, feed utilization, antioxidant capability, and stress resistance of juvenile L. vannamei reared under intensive stocking conditions.  相似文献   

4.
This study aimed to evaluate the effects of dietary supplementation with sodium butyrate or polyhydroxybutyrate (PHB) on growth performance, as well as changes in intestinal microbiota and hemato‐immunological parameters, of Litopenaeus vannamei reared under a superintensive biofloc system. Twelve 800‐L tanks were each stocked with 250 shrimp/m3 (3.96 ± 0.04 g mean initial weight) and reared over a 6‐wk period. The basal diet and two test diets supplemented with 2% of each feed additive. At the conclusion of the growth trial shrimp fed with the butyrate‐supplemented diet, as compared with the control shrimp, showed higher survival and productivity and lower total bacterial and Thiosulfate‐citrate‐bile salts‐sucrose Agar (TCBS) counts in the intestine. However, no differences were observed in other performance parameters analyzed. Shrimp fed with both supplementation regimens also showed an increase in total and granular hemocytes, as well as an increase in serum agglutination titer. Shrimp offered diets supplemented with sodium butyrate had higher counts of hyaline cells. Thus, for L. vannamei reared in a superintensive biofloc system, it can be concluded that dietary supplementation of sodium butyrate, more so than PHB, acted as an immune system modulator by reducing the concentration of pathogenic bacteria in shrimp gut, thereby increasing survival and productivity.  相似文献   

5.
In this study, a feeding trial followed by a challenge test was performed to evaluate effects of six herbal formulae which were different combinations of Astragalus polysaccharides (APS), chlorogenic acid (CGA) and allicin on growth performance, non‐specific immune response, antioxidant capacity, disease resistance and biomolecule damage of white shrimp Litopenaeus vannamei. Shrimp were fed seven diets, control diet (basal diet with no herbal formulae) and six herbal formula diets (G1–G6, basal diet supplemented with 0.1% APS + 0.05% allicin, 0.1% APS + 0.1% allicin, 0.1% CGA + 0.05% allicin, 0.1% CGA + 0. 1% allicin, 0.1% APS + 0.1% CGA and 0.1% APS + 0.1% CGA + 0.05% allicin respectively), for 21 days. After that, shrimp were challenged with Vibrio harveyi and then the cumulative mortality of shrimp was recorded for 7 days post challenge. The results showed that there were no significant differences in growth performance among all groups, while the non‐specific immune responses and antioxidant indexes were significantly improved (p < .05) in shrimp fed herbal formula diets when compared to the control. Meanwhile, the lowest cumulative mortality was observed in shrimp fed herbal formula diets with 0.1% APS, 0.1% CGA and 0.05% allicin supplementation after V. harveyi challenge. Additionally, herbal formulae could not cause biomolecule damage to the hepatopancreas of shrimp. In conclusion, these results indicated that synergistic effect of APS, CGA and allicin helped to boost immunity, antioxidant capacity and disease resistance of shrimp without biomolecule damage.  相似文献   

6.
Juvenile Litopenaeus vannamei farmed at 3.0 psu were fed five diets containing glucose, sucrose, wheat starch, corn starch or potato starch as the carbohydrate (CBH) source. Shrimp were fed for 50 days to explore the effect of dietary CBH source on growth, body composition and ammonia tolerance. The specific growth rate of body length of shrimp fed glucose was the highest and significantly higher than those fed potato starch. The survival rate of shrimp fed glucose was 89.44%, and it was the highest and significantly higher than those fed wheat starch. Whole shrimp body crude protein and lipid of the corn starch group were 140.2 g kg?1 and 10.1 g kg?1 respectively. And they were significantly higher than those fed wheat starch. Shrimp fed potato starch had higher hepatopancreas and muscle glycogen. Shrimp fed sucrose had higher glucose‐6‐phosphate dehydrogenase and lower pyruvate kinase activities (P < 0.05). Besides, shrimp fed starch produced more B cells in hepatopancreas tubules than those fed glucose or sucrose. Shrimp fed different sources of CBH differed in the number of R cells. After 96‐h of ammonia nitrogen challenge, the survival rate of the treatments from high to low in turn was glucose, wheat starch, corn starch, sucrose and potato starch, and no significant differences were observed among all treatments. Based on shrimp growth and the economic problems of practical production, we recommend wheat starch as CBH source in practical diets for L. vannamei farmed at low salinities.  相似文献   

7.
Two growth trials and a physiology assessment were conducted to evaluate three non‐genetically modified (GM) soybean cultivars as ingredients in practical diets for Pacific white shrimp, Litopenaeus vannamei. In addition, a commercially available fermented yeast product was evaluated as dietary supplement. For the growth trials (46 and 35 days, respectively, for trials 1 and 2), the basal diet was primarily composed of soybean meal (SBM), fishmeal (FM), whole wheat, corn protein concentrate, poultry meal (PM, pet food grade) and corn starch. Non‐GM cultivars were processed with novel methodologies to produce Navita? ingredients (N1, N2 and N3) which were incorporated at low (L) or high (H) levels into the experimental diets, in partial replacement of FM and full replacement of conventional SBM. The last two formulations incorporated the fermented yeast for a total of nine experimental diets (Table 1 ). Results from the growth trials indicate that shrimp fed diet 5 (HN2) exhibited significantly lower (p < .05) weight gain as compared to shrimp fed diets 1 and 2 (basal and LN1, respectively) in trial 1, as well as compared to animals fed diets 1, 2, 3 and 8 (basal, LN1, HN1 and basal + yeast) in trial 2. The feed conversion ratio significantly increased for shrimp fed diet 5, in contrast with shrimp fed diets 1, 2, 3 and 8 in trials 1 and 2, as well as compared to shrimp fed diets diet 6 (LN3) in trial 2. For the physiological assessment (stress and immune responses), only the effects of diets 1, 3, 8 and 9 (basal, HN1, basal + yeast and HN1 + yeast, respectively) were investigated. Granular cell counts were significantly higher for shrimp fed the yeast‐containing diets. Haemolymph glucose and haemolymph packed cell volume were significantly reduced for shrimp fed diets 3, 8 and 9. No significant differences were observed in total haemocyte counts, hyaline cells counts, semi‐granular cells counts, haemolymph protein, haemocyte phagocytic capacity and haemocyte respiratory burst activity. Results of this work indicate that selective soy breeding technology coupled with novel processing options has the potential to increase the nutritional value of conventional SBM for shrimp feeds. Trends on immune responses were more difficult to elucidate possibly due to the limited length of the feeding trial.  相似文献   

8.
The present work evaluated the effect of three inexpensive diets (frozen minced mussel and edible cockle (MMC), frozen minced squid (MS) and gilthead seabream feed (GSF)) on growth, survival, sex reversal, lipid classes and fatty acid (FA) profile of juvenile ornamental shrimp Lysmata seticaudata. Shrimp fed GSF displayed the highest survival rate (±SD) (85.2±1.8%) and the highest percentage (±SD) of shrimp changing from male to simultaneous hermaphrodite (SH) phase (25.2±2.2%). All diets promoted growth rates superior to those reported in the wild, with SH shrimp displaying higher total lengths (TL). Shrimp in SH phase fed GSF displayed the highest TL (±SD) (40.6±1.2 mm). Cultured shrimp reflected the lipid content of experimental diets, with shrimp fed GSF displaying the highest triacylglycerols and sterols (ST) contents. The higher rearing density induced by lower mortality rates of shrimp fed GSF, and the high ST levels present in the diet, may explain the higher proportion of shrimp in SH phase. The higher levels of highly unsaturated fatty acids (HUFA) displayed by MS did not promote higher survival or growth rates. The low polyunsaturated fatty acids and HUFA content of MMC was not reflected in cultured shrimp, probably because of a selective retention of these FA.  相似文献   

9.
Different levels of dietary chitosan on growth performance, survival and stress tolerance to air exposure was studied in tiger shrimp, Penaeus monodon. Shrimp (mean initial wet weight about 1.16 g) were fed with six different diets (C0, C0.05, C0.1, C0.2, C0.3 and C0.4) containing six level of chitosan (0%, 0.05%, 0.1%, 0.2%, 0.3% and 0.4% respectively) in triplicate for 60 days. Growth performance [final body wet weight (FBW); weight gain (WG); biomass gain (BG)] of shrimp fed chitosan‐containing diets were higher (P < 0.05) than that of shrimp fed the basal diet, shrimp fed C0.1 diet showed the highest value of growth performance. Survival of shrimp in C0.1 and C0.2 diet groups were higher (P < 0.05) than that of shrimp in C0, C0.05 and C0.4 diet groups but without statistical difference (P > 0.05) in shrimp fed C0.3 diet group. Whole body and muscle lipid contents decreased with increasing dietary chitosan levels. Plasma total cholesterol and triglyceride contents of shrimp fed C0 diet was significantly higher (P < 0.05) than that of shrimp fed chitosan‐containing diets. Plasma alanine aminotransferase (ALT) and aspartate aminotransferase (AST) activities of shrimp fed C0 diet were higher than those of shrimp fed chitosan‐containing diets. Digestive gland malondialdehyde (MDA) and carbonyl protein contents of shrimp fed chitosan‐containing diets were lower (P < 0.05) than that of shrimp fed C0 diet. Total haemocyte count of shrimp fed C0 diet was lower (P < 0.05) than that of shrimp fed chitosan‐containing diets. On the contrary, the haemolymph clotting time of shrimp fed C0 diet was higher (P < 0.05) than that of shrimp fed chitosan‐containing diets. In conclusion, all results suggested that dietary intake containing 0.1% and 0.2% chitosan enhanced the growth of shrimp, whereas a higher level than 0.3% and 0.4% decreased growth of shrimp. Second‐degree polynomial regression analysis of WG and BG indicated that the optimum supplement of dietary chitosan level should be 0.19–0.21%.  相似文献   

10.
The efficacy of hot‐water extract of tropical brown seaweed, Sargassum cristaefolium (SCE), supplemented in diets on immune response, stress tolerance, and disease resistance of Litopenaeus vannamei to Vibrio parahaemolyticus was evaluated. Shrimp were fed diets containing graded levels of SCE (0, 250, 500, 750, and 1000 mg/kg). The results showed that shrimp fed all diets containing SCE had significantly higher (P < 0.05) immune response in total hemocyte count (THC), differential hemocyte count (granular and hyaline cells), and phagocytic activity than those of shrimp fed the control diet. Similarly, in low dissolved oxygen stress tolerance test and the challenge test with V. parahaemolyticus, survival rates of shrimp fed all diets containing SCE were significantly higher (P < 0.05) (83–93% in stress test and 27–47% in challenge test) than those of shrimp fed the control diet (77 and 3.3%, respectively). These results suggest that oral administration of SCE at 500 and 750 mg/kg can be effectively used to enhance immune response, stress tolerance, and resistance of white shrimp, L. vannamei, against V. parahaemolyticus infection. These findings also confirm that using dietary SCE as immunostimulant is effective at increasing the nonspecific immune system in penaeid shrimp, L. vannamei.  相似文献   

11.
A 10‐week growth trial was run to evaluate effects of myo‐inositol (MI) on growth performance, haematological parameters, antioxidative capacity and salinity stress tolerance of Litopenaeus vannamei. Six practical diets supplemented with graded levels of MI (designated as MI0, MI600, MI1200, MI2400, MI 3600 and MI4800 for 448.8, 974.2, 1568.0, 2810.6, 3835.5 and 4893.6 mg/kg diet, respectively) were fed to six replicate groups of L. vannamei (mean initial body weight 0.63 ± 0.00 g). The results showed that significant increment of growth performance was observed in shrimp fed MI600 diet than those fed MI1200 diet. Lipid concentration in whole body of the shrimp fed MI600 diet was significantly increased. Shrimp fed MI0 diet had lower total protein (TP) as compared to shrimp fed the MI‐supplemented diets (except MI4800 diet). In general, lower activities of antioxidant enzymes and higher malondialdehyde (MDA) content in haemolymph and hepatopancreas were recorded in shrimp fed MI0 diet, compared to those fed the MI‐supplemented diets. Reduced survival after 7‐h salinity stress was present in shrimp fed MI0 diet as compared to those fed MI4800 diet. Dietary MI requirement for glutathione peroxidase activity of L. vannamei was 2705 mg/kg diet.  相似文献   

12.
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13.
This study evaluated the effect of dietary thiamin on growth performance, feed utilization and non‐specific immune response for juvenile Pacific white shrimp, Litopenaeus vannamei. Six isonitrogenous and isolipidic practical diets were formulated with graded thiamin levels of 6.9, 32.7, 54.2, 78.1, 145.1 and 301.5 mg kg?1 of dry diet, respectively. Each diet was randomly assigned to triplicate groups of 30 juvenile shrimp and provided four times each day to apparent satiation. Weight gain (WG) and specific growth rate (SGR) of the shrimp were significantly influenced by the dietary thiamin levels, the maximal WG and SGR occurred at 54.2 mg kg?1 dietary thiamin level. However, with further increase in dietary thiamin level from 54.2 to 301.5 mg kg?1, the WG and SGR significantly decreased. Shrimp fed the 54.2 mg kg?1 thiamin diet exhibited higher feed efficiency, protein efficiency ratio and protein productive value than those fed the other diets. Dry matter and protein content in whole body were significantly affected by the dietary thiamin levels. Thiamin concentration in hepatopancreas significantly increased when the dietary thiamin level increased from 6.9 to 145.1 mg kg?1. The total protein, glucose, triacylglycerol and cholesterol contents in hemolymph were not significantly affected by the dietary thiamin levels. Dietary thiamin had significantly influenced superoxide dismutase, catalase and lysozyme activities in hemolymph. Results of this study indicated that the optimal dietary thiamin requirements estimated using a two‐slope broken‐line model based on WG and thiamin concentration in hepatopancreas were 44.66 and 152.83 mg kg?1, respectively.  相似文献   

14.
The objective of this study was to evaluate inclusion of distiller's dried grains with solubles (DDGS) as partial replacement of commercial, solvent‐extracted soybean meal (SBM) in fish meal‐free diets for Pacific white shrimp, Litopenaeus vannamei. Aquaria connected to a recirculating biofiltration system were utilized to evaluate growth, survival, and feed conversion of shrimp during the 8‐wk feeding trial. Each 110‐L aquarium was stocked with 15 shrimp (mean individual weight 0.99 g) and fed one of five diets: a diet containing 20% fish meal (FM), which served as the control (Diet 1); a diet containing 0% FM and 52.5% SBM (Diet 2); and diets containing 0% FM and either 10, 20, or 30% DDGS as partial replacement of SBM (Diets 3, 4, and 5, respectively). Shrimp were fed according to a pre‐determined feeding chart five times daily (0730, 1030, 1330, 1630, and 1930 h) and there were three replicates per dietary treatment. The results from the feeding trial demonstrated that final weight, weight gain (g), and percentage weight gain were significantly higher (P < 0.05) for shrimp fed Diet 1 (10.96 g, 10.01 g, and 1051%, respectively) compared to shrimp fed diets containing DDGS; however, shrimp fed diets containing DDGS had similar (P > 0.05) final weight, weight gain (g), and percentage weight gain as shrimp fed a diet containing 0% FM and 52.5% SBM (Diet 2). Feed conversion ratio (FCR) of shrimp fed Diet 1 (2.84) was significantly lower (P < 0.05) compared to shrimp fed any other diet. Survival (%) was not different (P > 0.05) among treatments and averaged 77.3% for the study. This study demonstrated that practical shrimp diets containing no FM had an adverse impact on growth performance of white shrimp when grown in a clear‐water system and that further research is needed to refine diet formulations when culturing shrimp in these systems when attempting to feed a diet without FM.  相似文献   

15.
In this study, we replaced fish meal with peanut meal (PM) in isonitrogenous and isolipidic diets for Pacific white shrimp at inclusion levels of 0, 70, 140, 210, 280 and 350 g kg?1. The diets were hand‐fed to three independent groups of shrimp three times a day over a 6‐week period. Shrimp fed PM diets at a level of 280 g kg?1 or higher had lower per cent weight gain compared with those fed the basal diet, whereas shrimp fed PM diets at 140 g kg?1 or higher had a lower feed utilization and protein efficiency ratio compared with shrimp fed the basal diet. The feeding rate in shrimp fed PM diets at 350 g kg?1 and the survival and protease activity in shrimp fed PM diets at 210 g kg?1 or higher were lower than that in shrimp fed the basal diet. Diets containing 280 g kg?1 or higher of PM caused an increase in the whole‐body moisture content of the shrimp, but decreased whole‐body protein and ash contents compared with the basal diet. Nutrient digestibility was lower or tended to be lower in shrimp fed a PM diet compared with those fed the basal diet. The activities of peroxidase and acid and alkaline phosphatases in plasma decreased with increasing levels of PM inclusion up to 210 g kg?1. Superoxide dismutase activity decreased at dietary PM levels of 280 g kg?1 or higher. Aflatoxin B1 residue in the muscle was not affected by any of the treatments and remained low. The data suggest that up to 140 g kg?1 of PM could be included in practical diets for Pacific white shrimp.  相似文献   

16.
Two experiments were conducted to investigate the immune‐enhancing effect of dietary supplement with Astragalus polysaccharides (APS) on the Pacific white shrimp, Litopenaeus vannamei. In experiment 1, the optimal APS dose was determined based on the immune responses of shrimps fed APS diet for 30 days. In experiment 2, the effect of APS supplementation on immune response of shrimp suffering white spot syndrome virus (WSSV) challenge was determined. Results showed that the total haemocyte count and phagocytic activity in shrimps fed APS diets significantly (p < .05) increased in comparison with those fed the basal diet. Dietary supplement with APS markedly (p < .05) increased the activity of phenoloxidase (PO), total superoxide dismutase (SOD), lysozyme (LZM), acid phosphatase and alkaline phosphatase in shrimp hemolymph, but decreased the maleic dialdehyde (MDA) content. Significantly higher (p < .05) activity on PO, SOD and LZM and lower (p < .05) MDA content have also been found in shrimps suffering WSSV challenge. Therefore, APS could be used as a safe and effective feed additive in shrimp aquaculture, and the optimal dose of APS for the Pacific white shrimp was suggested to be 0.2 g/kg based on our results.  相似文献   

17.
A feeding trial was conducted to evaluate the efficacy of replacing fish meal (FM) with blood meal (BM), poultry by‐product meal (PBM), meat and bone meal (MBM) and shrimp head meal (SHM), rapeseed meal (RM) and peanut meal (PM) on a digestible basis of crude protein and lysine and methionine in five practical diets for the Pacific white shrimp at the FM levels of 300, 250, 200, 150 and 100 g kg?1 under laboratory conditions. Each of the five experimental diets was hand‐fed to four replicate tanks of shrimp with an average weight of 0.33 ± 0.03 g to satiation at each meal. The shrimp were fed three times a day over a six‐week period. The per cent weight gain of initial body weight (WG%) was significantly lower in shrimp fed 100 g kg?1 FM diet, but the value for hepatosomatic index (HSI) and the level of blood urea nitrogen (BUN) tended to be higher in shrimp fed 100 g kg?1 FM diet than those in shrimp fed other diets. The lowest value for feeding rate (FR) occurred for shrimp fed the basal diet and was significantly lower than that in shrimp fed the FM diets at 100–150 g kg?1. Shrimp fed diets containing 200 g kg?1 or lower FM had significantly lower feed utilization than those fed the 250 g kg?1 FM diet and the basal diet. The protein efficiency ratio (PER) in the shrimp fed the basal diet was significantly higher than in the other FM diets. Decreasing the FM replacement level significantly reduced nutrient digestibility except in the cases of ash and gross energy, but it did not affect the survival, condition factor (CF), body composition, digestive enzyme activity or plasma transaminase activity. The results of the study indicate that feeding a diet formulated on a digestible basis and involving FM replacement with other protein sources at a greater replacement proportion will not produce a level of shrimp growth equal to that achieved by feeding the basal diet.  相似文献   

18.
The effect of dietary astaxanthin on growth, survival, and stress tolerance was determined in postlarval Litopenaeus vannamei. An experiment was performed with postlarval shrimp (mean initial wet weight 1.2 mg) fed four isoenergic and isonitrogenous diets containing four supplemented levels of astaxanthin (0, 100, 200, and 400 mg/kg diet, respectively). Shrimp fed diets containing 100, 200, and 400 mg astaxanthin/kg diet for 30 d showed higher weight gain (WG, %) and survival compared to the control (without supplementation of astaxanthin). Specific growth rate (SGR, %/day) and final body wet weight (FBW, mg) showed the same pattern as WG. There were no significant differences in growth performance (FBW, WG, and SGR) among the groups fed the diets with astaxanthin supplementation at the termination of feeding trial. Survival of shrimp in the control and 100 mg/kg diet treatments was significantly lower than that of shrimp in the treatments with 200 and 400 mg/kg diet. After 9 d of a stress tolerance test, survival of shrimp in the 200 and 400 mg astaxanthin/kg treatments was significantly higher than that of shrimp in the 0 and 100 mg astaxanthin/kg treatments (P < 0.05). We concluded from this experiment that astaxanthin was a necessary ingredient for the development of larval L. vannamei. Considering the effect of astaxanthin on both, growth performance and survival of postlarval L. vannamei, the level of astaxanthin supplemented in the diet should be between 100 mg and 200 mg/kg of diet.  相似文献   

19.
This study was carried out to investigate the effect of water‐soluble polysaccharides extract of algae Ulva rigida (WPU) as dietary supplement on growth performance, antioxidant enzyme activity, lysozyme and phenoloxidase activity, and resistance of shrimp (Litopenaeus vannamei) subjected to bacterial infection with Photobacterium damselae. Three replicate groups of shrimp (1.0 g) were fed four diets containing four levels, 0 or control, 0.5, 1 and 1.5 g/kg of WPU for 8 weeks over the growth trial. Thereafter, 30 shrimps from each dietary treatment were infected with bacteria P. damselae to evaluate disease resistance of infected shrimp. The results of this study showed that WPU was effective as a growth promoter for L. vannamei. The best growth rate was observed in shrimp fed 1.5 g/kg of WPU diet. Regarding antioxidant defences, the diets supplemented with three levels of WPU stimulated glutathione peroxidase and catalase activates in experimental shrimps. MDA content of L. vannamei‐fed diet containing WPU 1.5 and WPU 1.0 was lower than WPU 0 and WPU 0. 5 diets. Also, lysozyme and phenoloxidase activities of shrimp receiving WPU at 1.0 and 1.5 level were significantly higher than those fed WPU 0 and WPU 0.5 diets. In addition, using WPU extract in all diets decreased mortality in L. vannamei in a dose‐dependent manner after challenge with P. damselae. These results suggest that incorporation of water‐soluble polysaccharides from green algae U. rigida at 1.5 g/kg doses improves growth and antioxidant activity and enhances the immune responses in shrimp L. vannamei.  相似文献   

20.
A feeding trial was carried out to determine the effects of bioflocs on dietary protein requirement in juvenile whiteleg shrimp, Litopenaeus vannamei. Four bioflocs treatments (BFT) and one control group were managed: BFT fed diets 25% of crude protein (CP) (BFT‐25%), 30% CP (BFT‐30%), 35% CP (BFT‐35%) and 40% CP (BFT‐40%), and clear water control without bioflocs fed with 40% CP (CW‐40%). Triplicate groups of shrimp (initial body weight, 1.3 g) were fed one of the test diets at a ratio of 7% body weight daily for 8 weeks. At the end of the feeding trial, significantly (P < 0.05) higher weight gain and specific growth rate were obtained in shrimp fed BFT‐35% and BFT‐40% compared to BFT‐25% and BFT‐30%. Shrimp fed BFT‐35% exhibited the lowest feed conversion ratio. Significantly higher muscle nucleic acid indices were also recorded such as DNA content in BFT‐30%, RNA content in BFT‐35% and RNA/DNA ratio than that of shrimp fed control. Total protein level in the haemolymph of shrimp fed BFT‐40% was significantly higher than those of shrimp fed BFT‐25% and BFT‐30%. Therefore, the present results demonstrated that, when L. vannamei juveniles were reared in bioflocs‐based tanks, dietary protein level could be reduced from 40% to 35% without any adverse effect on shrimp growth performance, body composition and haemolymph characteristics. [Correction added on 20 May 2015, after first online publication: sentence modified to clarify the reduction in dietary protein level.].  相似文献   

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