Pathophysiological changes associated with dietary melamine and cyanuric acid toxicity in red tilapia

This study examined the adverse effects of feed-delivered melamine (MEL) and cyanuric acid (CYA) in red tilapia. Diet 1 (without MEL and CYA), diets 2–4 (with MEL and CYA at 2.5, 5 and 7.5 g kg⁻¹ diet, respectively) and diets 5 and 6 (with either MEL or CYA at 10 g kg⁻¹ diet) were examined. MEL alone lowered both growth and FCR (P < 0.05), and CYA alone reduced the FCR of tilapia. Protein efficiency ratio and apparent net utilization of fish on diets 2–6 were poor (P < 0.05). The renal tubules of fish ingested MEL-CYA combination had melamine–cyanurate crystals. On the other hand, diets with only one chemical did not induce such crystals. MEL and CYA in whole body, fillet or viscera reflected their dietary inclusion levels. The levels of Hsp70 were increased in the liver of fish that ingested MEL and CYA, in combination or singly (P < 0.05). However, in the kidney, such an increase was visible only in the fish that received diet 4 (P < 0.05). Combination of MEL and CYA at inclusion levels > 5 g kg⁻¹ diet induced the activity of catalase in liver and the activity of glutathione peroxidase in liver and kidneys. Therefore, these adulterants should not be included in fish feeds.     

Effects of dietary protein and lipid levels on growth and energy productive value of pacific white shrimp,Litopenaeus vannamei,at different salinities

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.     

Dietary toxicity of manganese to shrimp and its accumulation in bioflocs

Bioflocs were produced in pilot‐scale biological reactors using acetate, glycerine or sugar as a carbon supplement while treating fish‐effluent waters. Bioflocs were dried and evaluated for nutritional quality and ingredient suitability. It was discovered that all bioflocs had excess manganese levels (9,500 mg kg^–1). Two trials were conducted as follows: (i) first feeding trial was a 6‐week experiment to determine the dietary toxicity of manganese to shrimp (Litopenaeus vannamei) in diets without bioflocs, and (ii) the second feeding trial (5 weeks) was conducted with the aforementioned bioflocs with elevated manganese content. In first feeding trial, experimental diets contained increasing concentrations of manganese: 260, 570, 1,100, 2,300, and 3,500 mg kg^–1. Levels of manganese above 570 mg kg^–1 significantly (p < .05) impacted shrimp growth. These results suggested that the maximum theoretical inclusion rate of these bioflocs into the diet was 100 g kg^–1. In second feeding trial, experimental diets contained the different sources of bioflocs: acetate biofloc 100 g kg^–1, glycerine biofloc 100 g kg^–1, sucrose biofloc 100 g kg^–1 replacing soybean meal and acetate biofloc 100 g kg^–1–FM (replaced fishmeal). Compared to the control, the glycerine biofloc 100 g kg^–1 and acetate biofloc 100 g kg^–1–FM significantly (p < .05) suppressed shrimp growth. The findings in this article demonstrate that careful considerations are needed in regard to potential elevated levels of trace elements in biofloc.     

Effect of dietary cornstarch levels on growth performance, digestibility and microscopic structure in the white shrimp, Litopenaeus vannamei reared in brackish water

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.     

Effects of dietary marine microalgae,Tetraselmis suecica,on production,gene expression,protein markers and bacterial count of Pacific white shrimp Litopenaeus vannamei

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.     

Effects of dietary astaxanthin on growth,antioxidant capacity and gene expression in Pacific white shrimp Litopenaeus vannamei

Pacific white shrimp Litopenaeus vannamei (1050 individuals with initial weight of 1.01 ± 0.001 g) were fed either control diet or one of six dietary astaxanthin (AX) concentration (25, 50, 75, 100, 125 and 150 mg kg⁻¹) diets for 56 days in 35 tanks (30 shrimp per tank). After 56 days of culture, shrimp‐fed AX125 and AX150 diets had higher (P < 0.05) weight gain, specific growth rate, total antioxidant status and lower (P < 0.05) superoxide dismutase (SOD), catalase (CAT) than shrimp fed control diet. After low dissolved oxygen stress for 1 h, survival rate of shrimp fed AX75, AX100, AX125 and AX150 diets was higher (P < 0.05) than that of shrimp fed control diet. Hypoxia inducible factor‐1α (HIF‐1α), cytosolic manganese superoxide dismutase (cMnSOD) and CAT mRNA expression levels of shrimp fed seven diets were significantly down‐regulated under hypoxia than under normoxia, but their expression levels were higher under hypoxia in shrimp fed AX‐supplemented diets than in shrimp fed control diet. About 70‐kDa heat‐shock protein (Hsp70) mRNA expression level of shrimp fed seven diets was significantly up‐regulated under hypoxia than under normoxia, but its expression level was lower under hypoxia in shrimp fed AX‐supplemented diets than in shrimp fed control diet.     

Effects of supplementing bioactive compounds to a formulated diet on sensory compounds and growth of shrimp,Litopenaeus vannamei (Boone, 1931)

Experimental diets were processed at the Oceanic Institute by adding various bioactive compounds (lutein, fucoxanthin, astaxanthins (Ax), glucosamine, carotenoid mix, phytosterol mix, bromophenol (Bp) mix or their combination) to a formulated (control) diet to examine their effects on sensory composition and growth of shrimp. These diets and a commercial feed were fed to ～1.6 g shrimp (Litopenaeus vannamei) in four replicates in an indoor laboratory under flow‐through conditions for 8 weeks. Results indicated that all the supplementations of the bioactive compounds did not improve shrimp growth (0.79–0.97 g week^?1) compared with that (0.94 g week^?1) of the control diet (P>0.05). However, inclusion of lutein (200 mg kg^?1) or carotenoid mix (827 mg kg^?1) in the control diet (with supplemental Ax) resulted in much higher free Ax (48.3 or 46.5 mg kg^?1) and esterified Ax (6.2 or 3.9 mg kg^?1) content in shrimp tails than the control diet (28.4; 1.4 mg kg^?1 respectively) (P<0.05). Inclusion of Bp (2 mg kg^?1) in the control diet resulted in higher levels of Bp (160 μg kg^?1) in shrimp tail muscle than the control diet (81 μg kg^?1) (P<0.05). Three free amino acids, glycine, proline and alanine might be mainly responsible for the sweet taste of L. vannamei. The results suggest that the supplementation of the bioactive compounds may not affect shrimp growth performance, but some may affect the composition and taste of shrimp.     

Effect of long-term administration of dietary β-1,3-glucan on growth, physiological, and immune responses in Litopenaeus vannamei (Boone, 1931)

β-1,3-Glucan at different dietary doses was administered to enhance the growth, immunity, and survival against nitrite stress in Pacific white shrimp, Litopenaeus vannamei. Four different diets supplemented with 0, 250, 500, or 1,000 mg of β-1,3-glucan kg⁻¹ diets were fed to L. vannamei. Growth performance (weight gain and survival rate), physiological conditions (blood total protein, glucose, lactate, triacylglycerols, cholesterol levels) and immunological responses (superoxide dismutase, catalase, lysozyme, acid phosphatase, and alkaline phosphatase activities) of shrimp were recorded after 84-day feeding and 120 h after exposed to nitrite-N. After 84-day feeding, 250 mg kg⁻¹ β-1,3-glucan diet resulted in better weight gain (P < 0.05). Before the nitrite stress, blood lactate, triacylglycerols, and cholesterol level in shrimp fed with 250 mg kg⁻¹ β-1,3-glucan diet were significantly higher than those observed in shrimp fed with other diets (P < 0.05). Higher activities of catalase, lysozyme, and alkaline phosphatase were observed in shrimp fed with 500 or 1,000 mg kg⁻¹ β-1,3-glucan diet as compared to those obtained in shrimp fed with other diets (P < 0.05). After 120-h nitrite stress, blood protein, lactate, superoxide dismutase, catalase, and alkaline phosphatase activities in shrimp fed with 500 or 1,000 mg kg⁻¹ β-1,3-glucan were significantly higher than those observed in shrimp fed with other diets (P < 0.05). Glucose and triacylglycerol levels of shrimp fed with 500 or 1,000 mg kg⁻¹ β-1,3-glucan were significantly lower than those observed in other diets (P < 0.05). In shrimp fed with 500 and 1,000 mg kg⁻¹ β-1,3-glucan and 120-h after nitrite stress, the mortality was significantly lower than that observed in shrimp of control. Together, in this 84-day feeding trial, 250 mg kg⁻¹ β-1,3-glucan improved growth, whereas 500 mg kg⁻¹ β-1,3-glucan preferentially improved nitrite resistance, probably through accelerating energy metabolism and activating immune system.     

Enhanced growth effects on shrimp (Litopenaeus vannamei) from inclusion of whole shrimp floc or floc fractions to a formulated diet

A growth trial was conducted to determine the effects of inclusion of whole shrimp floc or floc fractions to a control diet on growth and survival of shrimp (Litopenaeus vannamei). The floc sample was collected from marine shrimp culture tanks and partially fractionated by extraction with water, acetone and hexane. A series of diets was manufactured by inclusion of whole floc (intact or ground), each of the fractions or their combination to a control diet. These diets were fed to shrimp (approximately 1.0 g) in an indoor laboratory under flow‐through conditions for 8 weeks. It was found that addition of whole floc (200 g kg^?1) or floc fractions (24–200 g kg^?1) to the control diet improved (P < 0.05) shrimp growth rate without affecting (P > 0.05) shrimp survival (>81.3%). Although inclusion of whole floc reduced the crude protein and crude fat contents and gross energy of the control diet, shrimp fed the whole floc‐supplemented diets obtained the highest (P < 0.05) growth rates (1.01 and 1.03 g week^?1) among the shrimp fed the 11 tested diets including two control (0.81 and 0.85 g week^?1), two commercial (0.45 and 0.71 g week^?1) and five floc‐fraction‐added (0.91–1.00 g week^?1) diets. Many bioactive compounds in the floc that possibly affected shrimp growth were also analysed and quantified.     

Growth and body composition of juvenile white shrimp,Litopenaeus vannamei,fed different ratios of dietary protein to energy

A 10‐week feeding experiment was conducted to evaluate the effect of different protein to energy ratios on growth and body composition of juvenile Litopenaeus vannamei (initial average weight of 0.09 ± 0.002 g, mean ± SE). Twelve practical test diets were formulated to contain four protein levels (300, 340, 380 and 420 g kg^?1) and three lipid levels (50, 75 and 100 g kg^?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 g L^?1 during the experimental period. The results showed that the growth was significantly (P < 0.05) affected by dietary treatments. Shrimps fed the diets containing 300 g kg^?1 protein showed the poorest growth. However, shrimp fed the 75 g kg^?1 lipid diets had only slightly higher growth than that fed 50 g kg^?1 lipid diets at the same dietary protein level, and even a little decline in growth with the further increase of dietary lipid to 100 g kg^?1. Shrimp fed the diet with 420 g kg^?1protein and 75 g kg^?1 lipid had the highest specific growth rate. However, shrimp fed the diet with 340 g kg^?1 protein and 75 g kg^?1 lipid showed comparable growth, and had the highest protein efficiency ratio, energy retention and feed efficiency ratio among dietary treatments. Triglycerides and total cholesterol in the serum of shrimp increased with increasing dietary lipid level at the same dietary protein level. Body lipid and energy increased with increasing dietary lipid level irrespective of dietary protein. Results of the present study showed that the diet containing 340 g kg^?1 protein and 75 g kg^?1 lipid with digestible protein/digestible energy of 21.1 mg kJ^?1 is optimum for L. vannamei, and the increase of dietary lipid level has not efficient protein‐sparing effect.     

Evaluation of cholesterol additions to a soyabean meal-based diet for juvenile Pacific white shrimp, Penaeus vannamei (Boone), in an outdoor growth trial

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.     

Partial replacement of fish meal with peanut meal in practical diets for the Pacific white shrimp,Litopenaeus vannamei

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.     

Lupin kernel meal as fishmeal replacement in formulated feeds for the Whiteleg Shrimp (Litopenaeus vannamei)

Rapidly expanding global aquaculture requires sustainable, local protein sources to supplement the use of fishmeal. Lupin seed meal (Lupinus angustifolius) was tested as sustainable diet component for Whiteleg shrimp (Litopenaeus vannamei). Controlled feeding experiments were conducted in a recirculating aquaculture system for eight weeks. Juvenile shrimps were provided formulated diets containing various levels of lupin meal inclusion (0, 100, 200 and 300 g kg^?1) supplementing the fishmeal component, and a commercial feed as general reference. Shrimp survival, growth, metabolic and immune parameters were analysed. Survival did not differ significantly between groups. Growth performance was significantly impaired in shrimp fed diets containing more than 100 g kg^?1 lupin meal. Lupin meal supplementation did not affect haemolymph protein content, whereas glucose and acylglyceride concentrations varied between treatments and were highest in animals fed the 100 g kg^?1 lupin meal diet. Phenoloxidase activity was highest in shrimp fed 100 g kg^?1 lupin meal diet indicating improved immune status. The present study indicates that low inclusion levels of lupin meal do not cause adverse effects and seem to stimulate the immune system of juvenile L. vannamei.     

Effect of dietary lipid level on growth,lipid metabolism and health status of the Pacific white shrimp Litopenaeus vannamei at two salinities

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.     

Nutritive values of low and high fibre canola meals for shrimp (Penaeus vannamei)

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.     

Growth performance and color enhancement of goldfish,Carassius auratus,fed diets containing natural dyes extracted from annatto (Bixa orellana) seeds

ABSTRACT

The present study was conducted to evaluate growth performance and color enhancement of goldfish, Carassius auratus, fed diets containing 0, 50, 100, 200, and 250 mg kg^?1 diet of annatto dye (AD) for 60 days. The survival rate was significantly higher in fish fed 100, 200, and 250 mg AD kg^?1 diet over than these fed control and 50 mg AD kg^?1 diet (p < 0.05). AD significantly (p <0 .05) increased the pigmentation in the skin and caudal fin of goldfish in a concentration dependent manner (R² = 0.995, 0.997). The highest amount of total carotenoid deposition in fish skin and fins were given by diets containing 200–250 mg AD kg^?1 diet. The highest redness (a*) of 43.21 and yellowness (b*) of 12.53 were obtained by 250 and 50 mg AD kg^?1, respectively. The present results show that AD can be successfully used as an alternative natural carotenoid source in goldfish diets at levels of 200–250 mg AD kg^?1 diet.     

Effects of dietary administration of Macsumsuk® on growth and stress to low salinity and low dissolved oxygen in whiteleg shrimp,Litopenaeus vannamei (Boone, 1931) juveniles

An 8‐week study was conducted to explore the results of Macsumsuk^® as a feed additive on the stress tolerance and growth of Litopenaeus vannamei in 15 culture tanks of 36 L each. Three hundred shrimp averaging 0.1 ± 0.01 g were fed with five isonitrogenous (48.38 ± 0.38% CP) diets (in triplicate groups) containing kaolinite (Macsumsuk^®) at 0%, 0.3%, 0.6%, 1.2% and 2.4%, namely Mk₀, Mk_0.3, Mk_0.6, Mk_1.2 and Mk_2.4. Specific growth rate (SGR) and weight gain (WG) of shrimp fed diets Mk_1.2 and Mk_2.4 were significantly better than those of shrimp fed diet Mk₀ (p < .05). However, SGR and WG of shrimp fed diets Mk_0.6, Mk_1.2 and Mk_2.4 were not significantly different. Protein efficiency ratio (PER) and feed efficiency (FE) of shrimp fed diets Mk_1.2 and Mk_2.4 were significantly better than those of shrimp fed diets Mk₀, Mk₀.₃ and Mk_0.6. Furthermore, the survival of shrimp fed diet Mk_2.4 was significantly lower than that of shrimp fed diet Mk_0.6 (p < .05). Cumulative mortality of shrimp fed diet Mk_1.2 was significantly lower than that of shrimp fed diet Mk₀ at 1–1.5 hr post‐stress to low dissolved oxygen (from 6.1 mg/L to 2.9 mg/L) and 4–5 hr post‐stress to low salinity (from 32‰ to 1‰) (p < .05). The optimum dietary Macsumsuk^® level for juvenile L. vannamei was determined as 1.97% by the polynomial regression analysis of weight gain.     

Effects of dietary chitosan on growth,survival and stress tolerance of postlarval shrimp,Litopenaeus vannamei

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.     

Incorporation of a mixture of meat and bone meal,poultry by‐product meal,blood meal and corn gluten meal as a replacement for fish meal in practical diets of Pacific white shrimp Litopenaeus vannamei at two dietary protein levels

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.     

Effects of various dietary levels of copper hydroxychloride on growth performance and tissue response in Pacific white shrimp Litopenaeus vannamei fed practical diets

Two trials were conducted to evaluate the performance of Pacific white shrimp Litopenaeus vannamei offered diets containing various copper (Cu) levels from Cu hydroxychloride (Cu₂(OH)₃Cl) containing 58.81% copper in the clear water recirculating system. In both trials, the basal diet (360 g kg^?1 protein, 80 g kg^?1 lipid) containing approximately 10 mg Cu kg^?1 was primarily comprised of fishmeal, soybean meal, corn protein concentrate and whole wheat. In trial 1, test diets were produced supplementing the basal diet with 5, 10, 20, 40 and 60 mg Cu kg^?1 from Cu hydroxychloride. Four replicate groups of 15 shrimp per tank (initial weight 0.28 g) were offered diets in slight excess over 8 weeks. In trial 2, the basal diet was supplemented with 30, 90, 150, 210 and 270 mg Cu kg^?1 from Cu hydroxychloride. Seven replicate groups of 15 shrimp per tank (initial weight 0.22 g) were offered feed in slight excess over 7 weeks. At the end of the two growth trials, no significant differences were observed in final biomass, final mean weight, percentage weight gain, feed conversion ratio (FCR) and survival. In trial 1, the Cu concentrations of the carapace, hepatopancreas and whole shrimp linearly increased with increasing dietary Cu supplements. In trial 2, polynomial regression of Cu concentrations of the carapace, hepatopancreas and whole shrimp against analysed dietary Cu content indicated that a plateau was reached at 215 mg analysed Cu kg^?1. Results of this study indicate that there was no negative effect of high levels of Cu supplement with regard to growth and survival. Tissue levels generally increased up to around 200 mg Cu kg^?1 diet and then decreased, possibly indicating a shift in physiology.