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1.
A 8‐week feeding experiment was conducted to evaluate the effect of different dietary protein and lipid levels on growth and energy productive value of juvenile Litopenaeus vannamei, at 30 and 2 ppt, respectively. Nine practical diets were formulated to contain three protein levels (380, 410 and 440 g kg?1) and three lipid levels (60, 80 and 100 g kg?1). Each diet was randomly fed to triplicate groups of 30 shrimps per tank (260 L). The effects of salinity and an interaction between dietary protein level and lipid level on growth and energy productive value of shrimp were observed under the experimental conditions of this study. At 30 ppt seawater, shrimp fed with 440 g kg?1protein diets had significantly higher weight gain (WG) than those fed with 380 g kg?1 protein diets at the same dietary lipid level, and the 60 g kg?1 lipid group showed higher growth than 80 g kg?1and 100 g kg?1 lipid groups at the same dietary protein level. At 2 ppt seawater, the growth of shrimp was little affected by dietary protein treatments when shrimp fed the 80 and 100 g kg?1 lipid, shrimp fed the 80 g kg?1 lipid diets had only slightly higher growth than that fed 60and 100 g kg?1 lipid diets when fed 380 and 410 g kg?1 dietary protein diets. A significant effect of salinity on growth of shrimp was detected with the growth responses at 30 ppt > 2ppt (P < 0.05). Final body lipid content, body protein content and energy productive value of shrimp was significantly higher in animals exposed to 30 ppt than in shrimp held at 2 ppt.  相似文献   

2.
This study was undertaken to determine acceptable dietary concentrations of high-fibre canola meal (CMHF) and low-fibre canola meal (CMLF) for juvenile shrimp, Penaeus vannamei. Four groups of 0.78 g shrimp held in running, 24.0–27.8°C sea water on a 12 h light: 12 h dark cycle were each fed one of seven isonitrogenous (340 g kg?1 protein) and isoenergetic (18.5 MJ of gross energy kg?1) diets to satiation four times daily for 56 days. Each of the test canola protein products comprised either 150, 300 or 450 g kg?1 of the protein in a basal (practical) diet by replacement of one-third, two-thirds or all of the menhaden meal protein. Shrimp that ingested diets in which CMHF and CMLF comprised 450 and 300 g kg?1 of the protein, respectively, exhibited significant reductions in growth and feed intake relative to those fed the basal diet. Feed and protein utilization were not significantly depressed unless menhaden meal in the basal diet was completely replaced by CMHF or CMLF. In general, percentage survival and final whole-body levels of protein, minerals, and thyroid hormones were not significantly affected by dietary treatment. Terminal whole-body levels of moisture were raised significantly in shrimp fed diets containing the highest levels of CMHF and CMLF. Potassium levels were significantly higher in shrimp fed the diet containing the lowest level of CMLF relative to those fed the basal diet and the diet with the highest level of CMLF. Water stability of the diet pellets was negatively correlated with their levels of CMHF and CMLF. It is concluded that commercial high-fibre canola meal can constitute 300 g kg?1 of the dietary protein of juvenile shrimp (Penaeus vannamei) without compromising growth, feed intake and feed and protein utilization. However, because of a trend towards reduced shrimp survival at this dietary concentration of canola meal, it is recommended that this protein source not exceed 150 g kg?1 of the protein in practical juvenile shrimp diets. Fibre-reduced canola meal did not have improved nutritive value for shrimp. However, we postulate that one or more fibre-reduced, and solvent-extracted canola protein products may be cost-effective substitutes for fish meal protein.  相似文献   

3.
Three isonitrogenous diets containing 60 g kg–1, 90 g kg–1 or 120 g kg–1 lipid were formulated and fed to the Litopenaeus vannamei (2.00 ± 0.08 g) under two salinities (25 or 3 psu) in triplicate for 8 weeks. Shrimp fed 90 g kg–1 lipid had higher weight gain and specific growth rate than shrimp fed the other two diets regardless of salinity, and the hepatosomatic index increased with increasing dietary lipid at both salinities. The shrimp at 3 psu had significantly lower survival and ash content, higher condition factor, weight gain and specific growth rate than the shrimp at 25 psu. Increasing dietary lipid level induced the accumulation of serum MDA regardless of salinity, and at 3 psu, it reduced the serum GOT and GPT activities and the mRNA expression of TNF‐α in intestine and gill of L. vannamei. The hepatopancreatic triacylglycerol lipase (TGL) and CPT‐1 mRNA expression showed the highest value in shrimp fed 90 g kg–1 lipid diet at 3 psu. This study indicates that 120 g kg–1 dietary lipid may negatively affect the growth and induce oxidative damage in shrimp, but can improve immune defence at low salinity; 60 g kg–1 dietary lipid cannot afford the growth and either has no positive impact on the immunology for L. vannamei at 3 psu.  相似文献   

4.
The ability of Litopenaeus vannamei (initial mean weight: 0.96 ± 0.02 g) to utilize different levels of cornstarch was examined in terms of growth indices, body composition, digestibility and microscopic structure of the hepatopancreas. Six isonitrogenous semipurified diets were fed to satiation to shrimp for 8 weeks in triplicate tanks (30 shrimps per tank) connected to a natural brackish water (6–8 g L?1) recirculating system. Diets contained different levels of cornstarch (100, 150, 200, 250, 300 and 350 g kg?1) as the source of carbohydrate and were balanced using cellulose. Weight gain (WG), survival rate and feed conversion rate (FCR) were considerably affected by cornstarch levels of diets. The highest WG (453.6 g kg?1) and best FCR was observed in shrimp fed the 150 g kg?1 (cornstarch level) diet and was significantly (P < 0.05) higher than those fed diets containing 250–350 g kg?1 cornstarch. However, the survival rate reached maximum in shrimp fed the 100 g kg?1 diet (96.7), some 30% higher than the lowest rate, which was found in shrimp fed the 250 g kg?1 diet. Body lipid tended to be higher in shrimp fed diets with higher cornstarch levels. The apparent digestibility of dry matter and crude fat increased with increasing levels of cornstarch and, hence, decreasing levels of cellulose. In addition, histological study on shrimp fed 10–350 g kg?1 diets exhibited histological changes. The overall conclusion was that the optimum cornstarch level may be set at 100–200 g kg?1 when the diets contain 380 g kg?1 protein.  相似文献   

5.
The effect of chitosan, a polymer of glucosamine obtained by the deacetylation of chitin, on growth, survival and stress tolerance was studied in postlarval Litopenaeus vannamei. An experiment was performed with postlarval shrimp (mean initial wet weight 1.2 mg) fed five isoenergic and isonitrogenous diets containing five supplemented levels of chitosan (0, 0.5, 1, 2 and 4 g kg?1 diet, respectively). The five compound diets (C0, C0.5, C1, C2 and C4) sustained shrimp growth throughout the experiment. Growth performance (final body weights; weight gain; SGR: specific growth rate) in shrimp fed diet C2 was significantly higher than that in shrimp fed diets C0, C0.5 and C1 (P < 0.05), diet C4 treatment provided intermediate growth result. The survival in shrimp fed diet C1 was significantly higher than that in shrimp fed C0 diet (P < 0.05), other diets treatments gave the intermediate survival results. No significant differences were found in growth and survival between diet C2 and C4 treatments. After 9 days of a stress tolerance test, survival in shrimp fed diets C1, C2 and C4 was significantly higher than that in shrimp fed diets C0 and C0.5. We concluded from this experiment that the incorporation of a moderate dietary chitosan was beneficial to the development of postlarval L. vannamei. Considering the effect of chitosan on both growth and survival of postlarval L. vannamei, second‐degree polynomial regression of SGR and survival indicated optimum supplement of dietary chitosan at 2.67 and 2.13 g kg?1, respectively, so the level of chitosan supplemented in the diet should be between 2.13 and 2.67 g kg?1.  相似文献   

6.
A growth experiment was conducted to investigate effect of dietary protein to energy ratios on growth and body composition of juvenile Myxocyprinus asiaticus (initial mean weight: 10.04 ± 0.53 g, mean ± SD). Nine practical diets were formulated to contain three protein levels (340, 390 and 440 g kg?1), each with three lipid levels (60, 100 and 140 g kg?1), in order to produce a range of P/E ratios (from 22.4 to 32.8 mg protein kJ?1). Each diet was randomly assigned to triplicate groups of 20 fish in 400‐L indoors flow‐through circular fibre glass tanks provided with sand‐filtered aerated freshwater. The results showed that the growth was significantly affected by dietary P/E ratio (P < 0.05). Fish fed the diets with 440 g kg?1 protein (100 and 140 g kg?1 lipid, P/E ratio of 31.43 and 29.22 mg protein kJ?1) had the highest specific growth rates (SGR) (2.16 and 2.27% day?1, respectively). However, fish fed the diet with 390 g kg?1 protein and 140 g kg?1 lipid showed comparable growth (2.01% day?1), and had higher protein efficiency ratio (PER), protein productive value (PPV) and energy retention (ER) than other groups (P < 0.05). No significant differences in survival were found among dietary treatments. Carcass lipid content was positively correlated with dietary lipid level, but irrespective of protein level and inversely correlated with carcass moisture content. Carcass protein contents increased with increasing dietary lipid at each protein level. The white muscle and liver composition showed that lipid increased with increasing dietary lipid level (P < 0.05). Dietary protein concentrations had significant effect on condition factor (CF), hepatosomatic index (HSI) and viscerosomatic index (VSI) (P < 0.05). However, dietary lipid concentrations had no significant effect on CF, HSI (P > 0.05). Based on these observations, 440 g kg?1 protein with lipid from 100 to 140 g kg?1 (P/E ratio of 29.22 to 31.43 mg protein kJ?1) seemed to meet minimum requirement for optimal growth and feed utilization, and lipid could cause protein‐sparing effect in diets for juvenile Chinese sucker.  相似文献   

7.
An 8‐week feeding trial was conducted to evaluate the effects of ascorbic acid (AsA), in the form of l ‐ascorbyl‐2‐polyphosphate (LAPP) on growth performance, body composition, antioxidative capacity and salinity stress tolerance of juvenile Pacific white shrimp, Litopenaeus vannamei. Five practical diets (46% crude protein and 7.6% lipid) supplemented with graded levels of AsA (14.64, 48.55, 84.98, 308.36 and 639.27 mg kg?1 diet) were fed to five replicate groups of L. vannamei (mean initial wet weight 0.57 g). No significant differences were found on growth performance among all treatments. However, whole body lipid content significantly decreased with dietary AsA levels increasing. Activities of total antioxidant capacity, glutathione reductase and glutathione peroxidase were significantly affected by dietary AsA levels. Shrimp fed LAPP‐free diet had higher malondialdehyde content than those fed the diets supplemented with LAPP. Dietary AsA levels higher than 308.36 mg kg?1 diet increased the survival of shrimps after 1, 2 and 3 h of acute salinity change. Broken‐line regression analysis on survival after 3 h of salinity stress and second‐degree polynomial regression analysis on glutathione reductase data indicated that the optimal dietary AsA requirement of L. vannamei was estimated to be 306.39, 319.75 mg kg?1 diet respectively.  相似文献   

8.
The effect of substitution of fish meal (FM) by spray‐dried blood cell meal (SBCM) with microencapsulated dl ‐methionine supplementation in trial diets for Litopenaeus vannamei was evaluated. Six isonitrogenous (320 g kg?1) and isolipidic (85 g kg?1) diets were formulated to feed shrimp (2.3±0.2 g shrimp?1) for 56 days. Shrimp were fed with six diets in which FM protein was gradually replaced by SBCM protein (0%, 20%, 40%, 60%, 80% and 100% in diets 0–5). Growth performances and feed utilization of shrimp fed diets containing 0%, 3.5%, 7.0% and 10.5% SBCM protein were not significantly different (P>0.05). Growth, feed conversion ratio and protein efficiency ratio of shrimp fed diets (80 and 100% FM substitution) were significantly poorer compared with other treatments (P<0.05). With increased levels of dietary SBCM, apparent digestibility coefficient of dry matter, crude protein enhanced from 76.9% to 82.3%, 84.8% to 89.0%, but crude lipid decreased from 90.6% to 88.3% respectively. The carcass composition values were not significantly (P>0.05) affected by the replacement level of FM, except lipid. There were no significantly differences (P>0.05) in amino acid retentions among Diets 0–3. The results suggest that the dietary FM protein could efficiently be substituted by SBCM up to 60%, without adverse effects on the growth of L. vannamei.  相似文献   

9.
A 4‐week feeding trial was conducted to determine the effects of oxidized fish oil (OFO, POV: 234.84 meq kg?1) on growth performance and oxidative stress of Litopenaeus vannamei. Five diets containing various OFO levels (0, 25, 50, 75 and 100 g kg?1) with the same dietary lipid level were fed to L. vannamei. The results showed that the body weight gain and the specific growth rate of the shrimp fed with 50, 75 and 100 g kg?1 of OFO diets decreased significantly (P < 0.05), whereas the hepatosomatic index increased significantly (P < 0.05). The malondialdehyde concentrations in the serum and muscle of the shrimp fed with 50, 75 and 100 g kg?1 of OFO diets were significantly higher than that of the shrimp fed with fresh fish oil (P < 0.05). The total antioxidant competence decreased significantly compared with the control group. Therefore, dietary OFO affects the growth performance and increases the oxidative stress of shrimp.  相似文献   

10.
A 3 × 3 factorial experiment was conducted to determine proper levels of dietary protein, lipid and dextrin for juvenile flounder. Nine experimental diets were formulated to contain three protein levels (410, 460 and 510 g kg?1) and three lipid levels (60, 130 and 190 g kg?1) with corresponding dextrin levels (250, 150 and 50 g kg?1). Triplicate groups of fish (8.9 ± 0.4 g) were hand‐fed the diets to apparent satiation for 7 weeks in flow‐through system. Specific growth rate was the highest in fish fed the 510 g kg?1 protein diet with 60 g kg?1 lipid, and was not significantly different from that of fish fed 460 g kg?1 protein diet with 60 g kg?1 lipid. Feed efficiency ratio tended to increase as dietary protein level increased. The feed efficiency ratio of fish fed the 510 g kg?1 protein diets with 60–190 g kg?1 lipid levels was not significantly different from that of fish fed 460 g kg?1 protein diet with 60 g kg?1 lipid. Daily feed intake tended to decrease with increasing dietary lipid level at each protein level. Daily protein intake increased with increasing dietary protein level at 60 g kg?1 lipid level. Hepatosomatic index and visceralsomatic index increased with increasing dietary lipid level at each protein level. The lipid contents of liver, viscera and whole body, and concentrations of plasma total cholesterol and triglyceride increased with increasing dietary lipid levels; however, no significant difference was observed in the contents of dorsal muscle lipid. The results of this study suggest that the diet containing 460–510 g kg?1 protein with low lipid level (60 g kg?1) is optimal for growth and efficient feed utilization of juvenile flounder.  相似文献   

11.
A 6‐week feeding trial was carried out in glass tanks to determine the effects of partial replacement of fish meal (FM) with a combination of meat and bone meal (MBM), poultry by‐product meal (PBM), blood meal (BM) and corn gluten meal (CGM) in practical diets on the growth, nutrient digestibility and body composition of Pacific white shrimp. Six practical diets were formulated, containing two levels of crude protein (CP) (330 and 380 g kg?1) and similar crude lipid (CL) levels. For the 330 g kg?1 dietary protein level, 0, 357 and 714 g kg?1 FM were replaced by the mixture in Diets 1–3, respectively; while 0, 514 and 784 g kg?1 FM were replaced in Diets 4–6, respectively, for 380 g kg?1 dietary protein level. White shrimp‐fed diets containing 330 g kg?1 CP had significantly lower weight gain compared with white shrimp fed diets containing 380 g kg?1 CP. Increasing the mixture and dietary protein level significantly raised the body ash content of white shrimp. White shrimp fed a low‐protein diet obtained better nutrient digestibility compared with those fed a high‐protein diet.  相似文献   

12.
This study evaluated the effects of soy protein ratio, lipid content and the minimum dietary level of krill meal in plant‐based diets over the growth performance and digestibility of Litopenaeus vannamei. Nine plant‐based diets varied the soybean meal (SBM) and soy protein concentrate (SPC) inclusion ratio at 1 : 2.3, 1 : 1 and 2.5 : 1, and their dietary lipid content at 121.4 ± 9.4, 102.3 ± 1.2, and 79.9 ± 1.2 g kg?1 (in a dry matter basis). An additional diet containing 120 g kg?1 of fish meal (salmon by‐product) was used as a control. Krill meal was included at 0, 5, 10, 20 and 30 g kg?1 in a new set of plant‐based diets. After 10 weeks in clear‐water tanks of 0.5 m3, no effect of SBM:SPC ratio and dietary lipid content was detected on shrimp survival. However, dietary lipid levels of 80 and 121 g kg?1 combined with a high SPC to SBM resulted in the lowest final body weight and the poorest apparent crude protein digestibility, respectively. Krill meal increased feed intake at only 10 g kg?1, while at 20 g kg?1, it accelerated shrimp growth, increased yield and reduced food conversion ratio.  相似文献   

13.
This study was undertaken to determine the replacement value of Cassia fistula seed meal (CFM) for soybean meal (SBM) in practical diets of Oreochromis niloticus fingerlings. Five practical diets (350 g kg?1 crude protein) containing 0 g kg?1 (control), 170 g kg?1 (diet II), 340 g kg?1 (diet III), 509 g kg?1 (diet IV) and 670 g kg?1 (diet V) substitution levels of CFM for SBM were formulated and fed to triplicate groups of O. niloticus fingerlings (mean initial weight of 10.22 ± 0.03 g) for 70 days. Fish mortality increased linearly with increase in inclusion levels of CFM in the diet. Growth and diet utilization efficiency were depressed in fish fed diets containing CFM at varying inclusion levels. Feed conversion ratio, specific growth rate and protein efficiency ratio of O. niloticus fed on diet containing 170 g kg?1 substitution level of CFM were similar (P > 0.05) to the control diet. Digestibility of the different diets decreased with increase in inclusion levels of CFM. Fish fed diet containing 670 g kg?1 CFM had significantly lower carcass protein. However, no significant differences were observed in carcass protein and lipid contents between fish fed the control diets and diet containing 170 g kg?1 CFM. The most efficient diet in terms of cost per unit weight gain of fish was obtained in 170 g kg?1 CFM dietary substitution.  相似文献   

14.
Cholesterol is considered a required nutrient for penaeid shrimps, but an optimal level has not been defined. A 68-day grow-out trial was conducted in 1300-L outdoor tanks in Hawaii, USA, to determine the cholesterol level required in a soyabean meal-based diet for juvenile Pacific white shrimp, Penaeus vannamei (Boone). Test feeds were prepared by adding six cholesterol levels (1.0-10.2 g kg?1, as-fed basis) to a standard diet high in plant-protein meals, starch and flour. These feeds were provided to the shrimp three times daily. Harvest weights and weekly growth increments varied significantly among diets. The 2.3 g kg?1 and 4.2 g kg?1 cholesterol diets yielded better growth than the 1.0 g kg?1 and 10.2 g kg?1 diets. Survival and feed conversion ratios did not vary significantly among diets. Significant dietary cholesterol effects on growth of P. vannamei in conditions resembling commercial grow-out indicate that its inclusion in practical diets at more accurately defined levels is necessary. Optimal cholesterol levels for juvenile shrimp may be lower than those now utilized, and may vary relative to the contribution of free sterols from natural foods in shrimp ponds.  相似文献   

15.
An 8‐week feeding trial was conducted to investigate the optimum dietary protein and lipid levels for growth, feed utilization and body composition of Pseudobagrus ussuriensis fingerlings (initial weight: 3.40 ± 0.01 g). Twelve diets containing four protein levels (350, 400, 450 and 500 g kg?1 crude protein) and three lipid levels (50, 100 and 150 g kg?1 crude lipid) were formulated. Fish were randomly allotted to 36 aquaria (1.0 × 0.5 × 0.8 m) with 25 fish to each glass aquarium. Fish were fed twice daily (08:00 and 16:00) to apparent satiation. The results showed that weight gain and specific growth rate (SGR) decreased with increasing dietary lipid level from 50 to 150 g kg?1 at the same dietary protein level. Fish fed the diets containing 150 g kg?1 lipid exhibited higher feed conversion ratio (P < 0.05), lower protein efficiency ratio (PER) and nitrogen retention efficiency (NRE) relative to fish fed the diet containing 50 and 100 g kg?1 lipid. Weight gain and SGR significantly increased with increasing dietary protein from 350 to 450 g kg?1 at the same dietary lipid level, and even a little decline in growth with the further increase in dietary protein to 500 g kg?1. Daily feed intake, NRE and PER were significantly affected by both dietary protein and lipid levels (P < 0.05) and tended to decrease with increasing dietary protein and lipid levels. Whole‐body protein content increased as protein levels increased and lipid levels decreased. Whole‐body lipid and muscle lipid content increased with increasing dietary lipid level, and decreased with increasing dietary protein at each lipid level. There was no significant difference in condition factor and viscerosomatic index among fish fed the diets. Hepatosomatic index was affected by dietary lipid level (P < 0.05), and increased with increasing dietary lipid level at the same protein level. These results suggest that the diet containing 450 g kg?1 protein and 50 g kg?1 lipid with a P/E ratio of 29.1 mg protein kJ?1 is optimal for growth and feed utilization of P. ussuriensis fingerlings under the experimental conditions used in the study.  相似文献   

16.
The experiment was conducted to determine the leucine requirement of juvenile Pacific white shrimp Litopenaeus vannamei (Boone) in low‐salinity water (0.50–1.20 g L?1). Six diets were formulated to contain 410 g kg?1 crude protein with fish meal, peanut meal and precoated crystalline amino acids with different concentration of l ‐leucine (16.72, 19.60, 22.06, 24.79, 27.28 and 30.16 g kg?1 dry diet). Each diet was randomly assigned to triplicate groups of 30 shrimps (0.38 ± 0.002 g), and the feed trial lasted for 8 weeks. The results indicated that the maximum weight gain was observed at 24.95 g kg?1 dietary leucine group, whereas the diets containing higher leucine concentration conversely reduced the growth performance (P < 0.05). Moreover, the highest body protein content and body protein deposition and the lowest haemolymph AST and ALT activities were also found at 24.95 g kg?1 dietary leucine group. With the increase in leucine in diets, a dose‐dependent increase was found in body lipid content and haemolymph urea concentration. The polynomial regression calculated using weight gain, feed efficiency and body protein deposition indicated that the optimal dietary leucine requirement for L. vannamei reared in low‐salinity water was 23.73 g kg?1 leucine of dry diet, correspondingly 57.88 g kg?1 of dietary protein.  相似文献   

17.
This work evaluated the performance of Litopenaeus vannamei to low fish meal diets supplemented with 2‐hydroxy‐4‐(methylthio)butanoic acid (HMTBa). A basal diet with 150.0 g kg?1 of anchovy fish meal was designed. Two positive control diets were formulated to reduce fish meal at 50% and 100% with 1.0 and 2.0 g kg?1 of MERA? MetCa (calcium salt with 84% HMTBa activity), respectively. Two nearly equivalent diets acted as negative controls, without HMTBa supplementation. A total of 50 clear‐water tanks of 500 L were stocked with 2.22 ± 0.19 g shrimp under 70 animals m?2. Shrimp survival (92.3 ± 5.1% and 81.4 ± 8.0%), yield (808 ± 12 and 946 ± 17 g m?2) and FCR (2.17 ± 0.19 and 3.12 ± 0.37) showed no differences among diets after 72 or 96 days, respectively. A significantly higher shrimp body weight and weekly growth were observed for those fed with the basal diet or diets supplemented with HMTBa compared with non‐supplemented ones. This study has shown that L. vannamei growth, body weight, survival, yield and FCR were supported by HMTBa supplementation when 150.0 g kg?1 of fish meal was replaced by soybean meal and other ingredients, at 50% and 100%.  相似文献   

18.
An 8‐week feeding trial was conducted to evaluate the effects of dietary aflatoxin B1 (AFB1) on growth performance, haematological parameters and histological changes in juvenile Pacific white shrimp, Litopenaeus vannamei. Six practical diets (455 g kg‐1 protein, 78 g kg‐1 lipid) with different levels of AFB1 (0, 25, 50, 100, 500, 1000 μg kg?1) were formulated. Each diet was fed to triplicate groups of shrimps (initial weight: 0.52 g). The results showed that shrimp fed with control diet (0 μg kg?1 AFB1) had significant higher weight gain (WG) and specific growth rate (SGR) than other groups. However, there were no significant differences in feed efficiency (FE) or hepatosomatic index (HSI) among all groups. Compared to the control diet, AFB1 supplementation significantly changed the activities of shrimp serum alanine aminotransferase (ALT), aspartate aminotransferase (AST), total antioxidant capacity (T‐AOC) and glutathione S‐transferase (GST) and the content of cholesterol (CHO). Histological damages were identified in the hepatopancreas of shrimp when dietary AFB1 level was over 107.6 μg kg?1. Based on this study, it was concluded that the AFB1 level in Pacific white shrimp diet should be <38.1 μg kg?1.  相似文献   

19.
The marine flagellated Chlorophyta Tetraselmis suecica is among the most important live food species in marine aquaculture. In the present study, the effects of dietary supplementation of dried marine microalgae, Tetraselmis suecica, on growth performance; feed utilization; chemical composition; gene expression of superoxide dismutase (SOD), glutathione peroxidase (GPx) and insulin‐like growth factor 2 (IGF‐II) gene of Pacific white shrimp, Litopenaeus vannamei; muscle protein polymorphism; and microbial count were assessed and evaluated. Three hundred and sixty L. vannamei (postlarvae) Pls (0.124 ± 0.002 g) were randomly stocked into 40‐L glass aquaria (30 shrimp/aquarium) and fed three times daily four tested diets: a basal diet (control), diet incorporated with 2.5 g kg?1 dried T. suecica (T1), 5 g kg?1 dried T. suecica (T2) and 7.5 g kg?1 dried T. suecica (T3) in triplicates, for 90 days. At the end of the trial, the survival rate (SR) of L. vannamei fed diets supplemented with different levels of T. suecica was significantly (p < .05) higher than the control diet. The highest weight gain and specific growth rate and the best feed conversion ratio were recorded on L. vannamei fed a diet supplemented with a 7.5 g/kg dried T. suecica. The highest protein, lipid and ash contents were obtained in L. vannamei fed the diet containing 7.5 g/kg T. suecica, when compared with the remaining tested diets. The gene expression of antioxidant genes SOD and GPx was the lowest in the T3 group in comparison with the control group. Meanwhile, expression level of IGF‐II was higher in the T2 group. The total heterotrophic bacterial count was significantly (p < .05) increased with the cumulative T. suecica level, while no significant (p > .05) differences were found in the total Vibrio count among treatments. Overall, the present results have shown that the diet supplemented with the highest inclusion level of dried T. suecica resulted in improved growth and nutrient utilization.  相似文献   

20.
The ability of juvenile carnivorous southern catfish (Silurus meridionalis Chen) to use different levels, kinds and physic state (glucose, raw cornstarch and precooked cornstarch) of dietary carbohydrate was evaluated in term of growth performance. All diets contained 100 g kg?1 lipid and 16 kJ metabolizable energy. Three isonitrogeneus (400 g kg?1) diets were formulated to contain 150 g kg?1 raw cornstarch, precooked cornstarch and glucose. Another three isonitrogeneus (300 g kg?1) diets were formulated to contain 300 g kg?1 raw cornstarch, precooked cornstarch and glucose. A control diet was formulated with no carbohydrate containing 500 g kg?1 protein. Each experimental diet was fed to four tanks of 10 fish (28.3 ± 0.5 g) for 8 weeks at 27.5 °C. Specific growth rate (SGR) of 300 g kg?1 glucose diet was significantly lower than those of other diets (P < 0.05). Feeding rates (FR) of 300 g kg?1 glucose and control diets were significantly lower than those of the other diets (P < 0.05). Feed efficiency (FE) was significantly decreased with increased dietary carbohydrate level (P < 0.05). Feed efficiency of the 300 g kg?1 glucose diet was significantly lower than those of the 300 g kg?1 raw and precooked cornstarch diets (P < 0.05). The protein efficiency ratio (PER) was significantly increased with dietary carbohydrate level except that of the 300 g kg?1 glucose diet, which was lowest among all diets (P < 0.05). The results suggested that both dietary starch and glucose were utilized for energy in southern catfish and had a protein‐sparing effect. At 150 g kg?1 inclusion level, the utilization of raw and precooked cornstarch and glucose did not vary significantly, but a higher dietary glucose level (300 g kg?1) had a markedly detrimental effect on growth in southern catfish.  相似文献   

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