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1.
The marine centric diatom Chaetoceros muelleri has been widely used as live feed in fish and shellfish aquaculture due to its excellent nutritional properties. The growth of microalgae is affected by various nutritional and environmental parameters, and species specific optimization of these parameters is essential for the development of cost‐effective biomass production process. In this study, the growth of C. muelleri, was optimized using response surface methodology (RSM). The variables nitrate, phosphate, silicate, temperature, pH, salinity and agitation speed were initially screened for biomass production in C. muelleri using Plackett–Burman experimental design, and it was found that nitrate, phosphate, silicate, temperature and pH significantly influenced the biomass production. These variables were further optimized by central composite design of RSM for biomass production and nutrient composition, and the medium was re‐constituted accordingly to have 180 mg L?1 nitrate, 7.5 mg L?1 phosphate, 30 mg L?1 silicate, with optimum growth conditions of temperature at 31°C and pH 6.46. At the end of 10 days culture period under the above conditions, biomass, protein, lipid and carbohydrate significantly increased from 0.360 ± 0.01 mg L?1, 9.41 ± 0.02%, 18.11 ± 0.01%, 0.6 ± 0.02% to 1.16 ± 0.01 mg L?1, 11.02 ± 0.01%, 19.58 ± 0.01% and 0.77 ± 0.01% respectively. The biomass production of C. muelleri could be increased 3.2‐fold with an improved nutrient profile by modifying the growth factors, the study thus offering an optimized process for biomass production of C. muelleri.  相似文献   

2.
The aim of the study was to evaluate the performance of Litopenaeus vannamei in an intensive photo‐heterotrophic hypersaline system with minimal seawater replacement, and establish relationships between parameters of a stochastic production model and relevant water quality variables. Six experimental 1000 m2 lined ponds were stocked at a density of 120 shrimp m?2 for a 105‐day trial. Salinity increased from 37 to 45 ± 2 g/L, and the water level was maintained with the weekly addition of filtered seawater, equivalent to 1.6% per day. The stochastic model predicted that, at harvest, there is 95% confidence that the system produces between 12.1 and 14.7 t/ha with a mean final individual weight of 13.1 g and a mean survival of 84.2%. Sensitivity analyses showed that dissolved oxygen and individual final weight of shrimp were the main variables influencing yield variance. Nitrogenous compounds were maintained between optimal cultivation levels (NH3–NH4+ = 0.73 ± 0.43 mg/L, N–NO2? = 0.09 ± 0.05 mg/L, N–NO3? = 3.22 ± 0.11 mg/L). Heterotrophic bacteria (6.6 ± 3.4 × 105 CFU/ml) and chlorophyll‐α concentration (108.5 ± 80.2 μg/L) showed a similar development pattern, indicating a strong relationship between bacteria and microalgae during cultivation. Vibrio spp. concentrations were low (1.24 ± 1.42 × 103 CFU/ml). It was shown that the photo‐heterotrophic system could be used in hypersaline conditions, typical of semi‐arid regions, to consistently produce between 12.1 and 14.7 t/ha in 15 weeks.  相似文献   

3.
A 60‐day feeding trial was conducted to optimize the inclusion level of de‐oiled rice bran (DORB) in the diet of Labeo rohita fingerlings. Six iso‐nitrogenous (260g/kg), iso‐lipidic (70g/kg) and iso‐energetic (15 MJ/Kg) diets were prepared with different inclusion level of DORB viz., T33, T38, T43, T48, T53 and T58. One hundred and eighty fingerlings (9.8 ± 0.5 g) were randomly distributed in seven experimental groups in triplicates following a completely randomized design. The weight gain %, specific growth rate, protein efficiency ratio and feed efficiency ratio were found similar in 33%, 38% and 43% DORB fed groups. The expression of both insulin‐like growth factors I and II (IGF‐I and II) was significantly (p < 0.05) higher in T33, T38 and T43 groups. Based on second order polynomial regression analysis (y = ?0.0059x2 + 0.4573x ? 4.8404, R2 = 0.95), the expression of IGF‐I was found to be maximum at 39.5% inclusion level of DORB. Significantly (p < 0.05) lower muscle RNA content, RNA‐DNA ratio and higher feed conversion ratio were found in T58 group. Hence, from these results, it can be concluded that the optimum inclusion of DORB in the diet (260g/kg CP and 70g/kg lipid) of L. rohita should be 39.5% to support maximum nutrient utilization and growth performance.  相似文献   

4.
Two fresh diets were tested on the biological performance of males and females of Octopus vulgaris under industrial rearing conditions in floating cages. The presence of females could potentially release paralarvae to the natural environment (‘integrated aquaculture’). Octopuses were fed on a single diet of bogue (aquaculture by‐product), and on a mixed diet (60–40% crab‐bogue), in two trials. In Trial 1 (918 ± 125 g), growth was higher in octopuses fed on the mixed diet (1.9–2.0%d?1) than in those fed on the bogue diet (1.8–1.9%d?1) irrespective of sex, and mortality was 3% regardless of sex and diet. In Trial 2 (1483 ± 269 g), growth was higher in males fed on the mixed diet (1.8%d?1) than in males fed on the bogue diet (1.4%d?1), both higher than females (1.1–1.3%d?1), and mortality was 22–28% regardless of sex and diet. Best biological performance in trial 1 was related to the lack of functional maturation in females, evidence by the low average gonadosomatic index (2.0–3.6%) in comparison with trial 2 (8.8–11.4%), regardless of diet. No correlations between final weight and sexual maturity indices were found, so the length of the rearing period to maximize biomass increment or to release paralarvae depends on functional maturation in females.  相似文献   

5.
In this study, we have tested the effect of seaweed stocking density in an experimental seaweed biofilter using the economically important red seaweed Hydropuntia cornea integrated with the cultivation of the pink shrimp Farfantepenaeus brasiliensis. Nutrient removal efficiency was evaluated in relation to seaweed stocking density (2.5, 4, 6 and 8 g fw L?1). Total ammonia nitrogen (TAN) was the main nitrogen source excreted by F. brasiliensis, with concentrations ranging from 41.6 to 65 μM of NH4+‐N. H. cornea specific growth rates ranged from 0.8 ± 0.2 to 1.4 ± 0.5% day?1 with lowest growth rates at higher seaweed stocking density (8 g fw L?1). Nutrient removal was positively correlated with the cultivation densities in the system. TAN removal efficiency increased from 61 to 88.5% with increasing seaweed stocking density. Changes in the chemical composition of the seaweed were analysed and correlated with nutrient enrichment from shrimp effluent. The red seaweed H. cornea can be cultured and used to remove nutrients from shrimp effluents in an integrated multi‐trophic aquaculture system applied to a closed recirculation system. Recirculation through seaweed biofilters in land‐based intensive aquaculture farms can also be a tool to increase recirculation practices and establish full recirculation aquaculture systems (RAS) with all their known associated benefits.  相似文献   

6.
The experiments explored the pharmacokinetics (PK) properties of oxolinic acid (OXA) after oral administration at three dosages (10, 30 and 80 mg/kg) via medicated feed in the shrimp. The results showed that the Cmax values of 4.31, 14.93 and 16.62 mg/L and AUC0–∞ values of 92.61, 252.30 and 364.27 mg hr?1 L?1 were observed at three OXA dosage groups in the haemolymph respectively. In the hepatopancreas, Cmax values of 7.90, 27.23 and 60.51 mg/kg and AUC0–∞ values of 42.01, 133.06 and 219.06 mg hr?1 L?1 were observed at 0.5 hr post administration respectively. In the muscle, Cmax values of 1.62, 5.80 and 7.36 mg/kg and the AUC0–∞ values of 25.64, 98.10 and 134.24 mg hr?1 L?1 were observed at 2 hr post administration respectively. In the gills, Cmax values of 2.87, 8.08 and 12.12 mg/kg and the AUC0–∞ values of 51.38, 118.65 and 206.48 mg hr?1 L?1 were observed at 4 hr post administration respectively. In addition, the in vitro MIC values of OXA at three dosages against 132 strains of Vibrio were examined and showed that the minimum inhibitory concentration (MIC) values for OXA primarily ranged from 0.15–1.25 µg/ml, including eight strains of Vibrio showing MIC values ≥5 µg/ml. The MIC50 and MIC90 values of 132 strains were 0.62 and 1.25 μg/ml respectively. The AUC0–24/MIC90 ratios of Vibrio were 140.4 in 30 mg/kg group. Furthermore, the P‐glycoprotein (P‐gp) expression was determined in shrimp tissues after administration to three dosage groups (10, 30 and 80 mg/kg). The results showed that P‐gp expression was up‐regulated in the hepatopancreas (5.36‐, 13.68‐ and 31.06‐fold respectively) compared with the control group.  相似文献   

7.
On the basis of multiple single‐factor studies, the best conditions for each factor were selected by comparison. Taking the biomass, polysaccharide and protein yields of chlorella as response values, the four‐factor and three‐level response surface design experiment was performed on four parameters that significantly affected the response values to further determine the optimal conditions. The optimal parameters of the culture process were nitrogen source (urea), carbon source (sodium carbonate), nitrogen concentration (15.80 mmol/L), carbon concentration (0.36 mmol/L), phosphorus concentration (0.2 mmol/L), magnesium concentration (0.33 mmol/L), calcium concentration (0.25 mmol/L), iron concentration (0.02 mmol/L), initial pH (7.0), inoculation amount (6%) and ventilation capacity (40 L/hr). According to this process, the biomass, polysaccharide and protein yield of Chlorella sorokiniana obtained from indoor culture were close to the predicted value, which were more than three times as much as before, reaching 3.58, 0.52 and 0.46 g/L respectively. Chlorella sorokiniana, which was cultured outdoor according to the optimized process, increased its biomass, polysaccharide and protein yield by more than 1.5 times. Chlorella sorokiniana was significantly different before and after optimized culture. This provides a good source for the research of polysaccharide and protein of C. sorokiniana and helps the further study of its structure and biological activity, which makes the further development of its function more possible.  相似文献   

8.
Stocking density is a biotic factor affecting the production of cultivated animals in aquaculture. Herein, a rearing trial was conducted to investigate the impact of stocking density on the survival, growth performance and physical injury of Marsupenaeus japonicus juveniles in a flowing water aquaculture system. Five stocking densities were examined in this study, that is, 10, 20, 40, 80 and 160 individuals/m2. Throughout the experiment, ammonia nitrogen and nitrite concentrations ranged from 0.02 ± 0.006 mg/L to 0.08 ± 0.035 mg/L and 0.002 ± 0.001 mg/L to 0.076 ± 0.021 mg/L respectively. The survival rate, specific growth rate (SGR), weight gain (WG), absolute growth rate (AGR) and coefficient of variation for weight (CV) across the stocking densities ranged from 90.38 ± 3.20% to 94.33 ± 4.73%, 1.42 ± 0.16%/day to 1.53 ± 0.05%/day, 1.09 ± 0.19 g to 1.15 ± 0.16 g, 0.018 ± 0.003 g/day to 0.019 ± 0.004 g/day and 16.21 ± 5.78% to 35.09 ± 10.68% respectively. Within the investigated densities, the survival rate and the abovementioned growth parameters were not significantly (p > .05) affected by the stocking density, consequently, a higher stocking density resulted in a significantly (p < .05) greater final biomass. The results regarding physical injury showed that the antennal breakage rate displayed a tendency of a positive correlation with the stocking density. Overall, the current study provides basic data for establishing a viable intensive farming system for M. japonicus and a promising indicator for easily assessing the crowding stress status of M. japonicus.  相似文献   

9.
Stock density is one among the most important factors in aquaculture that directly influences the growth of organisms; however, there is limited information about the effects of stocking density on growth performance of sea cucumber Holothuria tubulosa (Gmelin, 1788) that has a commercial potential and represents a new species for aquaculture. In this study, we investigated the effect of stocking densities on the growth performance of juvenile H. tubulosa (40.3 ± 3.34 g) in laboratory conditions. Stocking densities were selected as 6, 15 and 30 ind m?2 with total biomass 253.3 ± 0.18, 601.2 ± 0.11 and 1201.4 ± 0.15 g m?2 respectively. We monitored the growth by wet weights and calculated the growth performance through weight gain, growth rate, specific growth rate, relative weight gain, coefficients of variation and survival rate during 8 weeks of research period. We found that individual mean weight gain in 6 ind m?2 group was approximately 29.53 g while it was 3.03 g and ?4.36 g for 15 ind and 30 ind m?2 groups respectively. Results have shown that the specific growth rate tends to decrease as the number of individuals in unit area increases. The final mean weight, growth rate, specific growth rate, relative weight gain and coefficients of variation were significantly different among treatment groups. In conclusion, a density of 6 ind m?2 is recommended for stocking juvenile H. tubulosa under rearing conditions. Stocking density of 15 ind m?2 is not favourable for long term as the growth rate is negligible where 30 ind m?2 should be avoided in tank‐based rearing units.  相似文献   

10.
The red alga Chondria crassicaulis has a wide‐ranging bioactive chemical composition and is used as a local foodstuff, representing a potentially new cultivar in Korea. The cultivation techniques were developed by examining the monthly changes in frond weight in a field population of C. crassicaulis from November 2016 to October 2017. For seedling production, temperature and irradiance effects on the attachment and growth of vegetative propagules of C. crassicaulis were evaluated. In addition, effects of day length and salinity on the propagule growth were examined. C. crassicaulis is a year‐round species with a maximum frond wet weight of 817 mg observed in July 2017, as seawater temperature increases to 20°C. The attachment of vegetative propagules was significantly affected by temperature and irradiance, with maximal values detected at 20–25°C and 60 µmol photons m?2 s?1. The relative growth rates of vegetative propagules of C. crassicaulis were the highest at 20–25°C, 60 µmol photons m?2 s?1, and a salinity of 25 psu. In conclusion, due to its tremendous tolerance under variable environmental conditions, the vegetative propagules of C. crassicaulis can be used as seedlings for mass cultivation.  相似文献   

11.
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   

12.
Growth parameters of whiteleg shrimp Litopenaeus vannamei and red seaweed Gracilaria corticata were measured using integrated culturing method under zero‐water exchange system in a 45‐day period. A 2 × 3 factorial design was used with two levels of shrimp stocking densities and three levels of seaweed weight densities. G. corticata was cultured on a net tied to a round polyethylene frame. Culture tanks were filled with 750‐L filtered seawater. A 40‐W compact fluorescent lamp was hung over each tank to provide adequate and sufficient light for seaweed growth. Growth parameters of shrimp and seaweed such as specific growth rate (SGR), weight gained (WG) and average daily growth (ADG) were computed based on the initial and final weight of shrimp and seaweed. The maximum and minimum SGR of L. vannamei (1.97 and 1.69%/day) were observed in treatment S1A3 (25 shrimp/m2 and 400 g seaweed/m2) and S2A1 (50 shrimp/m2 without seaweed) respectively. The best survival rate (94.67 ± 1.33%), WG (129.9 ± 2.9%) and feed conversion ratio (1.67 ± 0.04) were also observed in treatment S1A3. The SGR of G.corticata in the treatment S1A3 (1.97 ± 0.00%/day) was significantly higher, compared to others. Strong positive correlations were obtained between the density of G. corticata and the growth parameters of L. vannamei. The red seaweed G. corticata could boost the growth parameters, survival rate and total production of L. vannamei under zero‐water exchange system.  相似文献   

13.
In this study, total phenolic and flavonoid contents of grapefruit peel extract (GPE) were equal to 117.3 ± 0.3 µg of gallic acid/mg and 39.30 ± 0.1 µg of quercetin/mg respectively. Caspian white fish (n = 180, 4 ± 0.9 g body weight) was fed with supplemented diets, including 0, 6.25, 12.5 and 25 mg of GPE/kg for 60 days at 25 ± 1°C. The growth performance was markedly improved in fish fed with 25 mg/kg of GPE compared to others (p < 0.05). Moreover, fish fed with 25 mg/kg of GPE showed a significant increase in red blood cell (2.65·106 cell/mm3), white blood cell (17.75·103 cell/mm3), packed cell volume (48%) and haemoglobin concentrations (8.75 g/dl) compared to the control (p < 0.05). However, the highest alanine aminotransferase (140 U/L), alanine transaminase (14.5 U/L), and alkaline phosphatase (18.5 U/L) were observed in control group. Morphological analysis of intestine revealed the highest amount of villus width (8.4 µM), height (32.86 µM) and surface area (342.7 µM2) in fish fed with 25 mg/kg of GPE (p < 0.05). In conclusion, supplementing feed with GPE at 25 g/kg can improve growth performance and haemato‐biochemical parameters of Caspian white fish fry.  相似文献   

14.
The aim of this study was to determine the growth performance, meat quality and colour attributes of large rainbow trout (Oncorhynchus mykiss) in net cage systems in the southern Black Sea coasts of Turkey. In the study, large rainbow trout with an initial weight of 1,322.07 ± 57.72 g were reached to 3,385.30 ± 140.98 g and the survival rates were 95.69 ± 1.32% in 5‐month production period. Crude protein and crude fat values of fish meat were ranged between 16.75 ± 0.07–20.18 ± 0.90% and 9.22 ± 0.15–12.29 ± 0.42%, respectively (p < .05). The essential and non‐essential amino acid values were between 12.92 ± 0.02–13.09 ± 0.01 g/100 g and 11.97 ± 0.14–11.47 ± 0.01 g/100 g, respectively (p > .05). C20:5n‐3, C22:6n‐3, ?3 and ?6 values in fish meat were between 4.32 ± 0.02–4.30 ± 0.08% (p < .05), 8.31 ± 0.10–7.72 ± 0.15% (p < .05), 13.41 ± 0.10–12.93 ± 0.23% (p < .05) and 21.85 ± 0.06%‐19.74 ± 0.36 (p < .05), respectively. As a result, it can be concluded that large rainbow trout cultured in the southern Black Sea coasts of Turkey is a rich source of food in terms of fatty and amino acid compositions and atherogenicity index, thrombogenicity index and hypocholesterolaemic/hypercholesterolaemic values.  相似文献   

15.
We examined if minimum water exchange could spare dietary methionine (Met) required for maximum growth performance of juvenile Litopenaeus vannamei reared in an intensive outdoor system. Shrimp of 1.98 ± 0.13 g were stocked at 70 animals/m2 and reared for 72 days in 50 tanks of 1 m3 under flow‐through (14.4% a day) and static (1.4%–2.9% a day) green‐water conditions at 32.0 ± 3.7 g/L salinity. Five diets with a minimum inclusion of fishmeal supplemented with a dipeptide, dl ‐methionyl‐dl ‐methionine, were formulated to contain increasing levels of Met, 4.8, 6.2, 7.2, 8.1 or 9.4 g/kg (on a dry matter basis). Each of the five diets were fed four times daily to five replicate groups. Dietary Met and water exchange significantly influenced shrimp survival, gained yield, apparent feed intake, food conversion ratio and final body weight (p < .05). Raising shrimp under limited water exchange, i.e., static versus flow‐through spared the dependence on higher levels of dietary Met to maximize shrimp body weight, from 9.4 g/kg to 8.0 g/kg (14.0 and 12.6 g/kg Met+Cys respectively). In an intensive rearing system, a reduction in water exchange is desirable as it leads to a lower need for supplemental dietary Met.  相似文献   

16.
The present study evaluates the effect of two temperatures, 14°C (T14) and 18°C (T18), on yield and the presence of cranial abnormalities during early development in north palm ruff (Seriolella violacea). Different time indices – days post‐hatching (DPH), degree‐days (D°) and effective degree‐days (D°eff) – were used to analyse growth during cultivation. Several ontogenetic events were achieved in less time during cultivation at 18°C. Additionally, a larger total length and final weight, as well as a higher survival rate, were achieved after 80 days of culture at higher temperatures (T18 = 55.5 ± 1.5 mm; 2.87 ± 0.21 g; 1.80 ± 0.18% and T14 = 24.3 ± 2.2 mm; 0.26 ± 0.08 g; 1.33 ± 0.12%). D° and D°eff were valid as independent temperature indices for predicting the growth response of S. violacea against thermal variations. The frequencies of cranial skeletal abnormalities (mouth and opercular complex) were evaluated in the pre‐flexion, flexion, post‐flexion and juvenile stages. However, the frequency of cranial skeletal abnormalities at the end of this study was not significantly influenced (P > 0.05) by temperature, and values below 21% were recorded in both treatments. These results can be of practical use for optimizing culture conditions to maximize the yield and quality of S. violacea juveniles.  相似文献   

17.
The effects and commercial implications of aquatic plant addition, and variable prawn stocking density and supply of commercial aquafeed on water quality, prawn production and economic benefit, are investigated in a prawn (Macrobrachium rosenbergii) + plant (Hydrilla verticillata) co‐culture system. Our experimental design includes a control (PM, prawn monoculture without H. verticillata, with 30 prawns/m2) and four treatments with 15% plant cover of total pond area in each replicate. Dissolved oxygen, pH, N, P, total ammoniacal nitrogen, nitrite and nitrate in this co‐culture system were significantly lower than those of PM. Prawn survival (96.2 ± 14.9%), average final weight (68.5 ± 4.9 g) and yield (879.1 ± 102.4 kg/ha) in treatment 20W80%A (20 prawns/m2, 80% of control aquafeed) were obviously greater than in PM and other treatments. Despite small males (SM) and immature females (IF) being predominant in prawn + plant cultures, more than 77.2% of prawns reached or exceeded 40 g on completion of trials, and by six months were of appropriate size for market. We report culture of M. rosenbergii with H. verticillata to be both feasible and profitable. The optimal treatment, a stocking density of 20 prawns/m2 with these plants, enabled reduction of commercial aquafeed to 20% conventional culture levels. For this optimal treatment, we estimate total gross revenue, profit and internal rate of return to be US$ 6,593.3 ± 103.3 ha?1, US$ 3,095.5 ± 42.6 ha?1 and 127.5 ± 20.7% for 20W80%A respectively; we estimate U.S. Dollar (US$) invested generates 3.87 times conventional culture revenue. Co‐culture of M. rosenbergii and plants renders prawn production ecologically and economically feasible on larger farms.  相似文献   

18.
A 12‐week feeding trial was conducted to determine the dietary phosphorus requirement of Heteropneustes fossilis fingerlings (7.7 ± 0.04 g). Fish were fed casein–gelatine‐based purified diets in triplicate groups near satiation with seven different levels of dietary phosphorus (3.2, 5.2, 7.2, 9.2, 11.2, 13.2 and 15.2 g/kg dry diet). All diets were formulated to be isoproteic (400 g/kg) and isoenergetic (17.89 kJ/g). Highest absolute weight gain (68.38 g/fish), best feed conversion ratio (1.48), protein retention efficiency (30.74%), protein gain (12.44 g/fish), haemoglobin (11.19 g/dL), RBCs (3.12 x106/mm3), haematocrit (33.44%) and serum phosphate (2.82 mg/L) were found at 9.2 g/kg phosphorus. Hepatic superoxide dismutase and catalase activity were also significantly influenced by the dietary phosphorus levels. Whole body and vertebrae phosphorus concentrations increased significantly as the amount of dietary phosphorus increased from 3.2 to 11.2 g/kg dry diet and then plateaued. More accurate information on dietary phosphorus requirement was obtained by subjecting the AWG, FCR, vertebrae phosphorus and whole body phosphorus concentrations data against various levels of dietary phosphorus to broken‐line analysis, which yielded the requirement in the range of 9.0–11.0 g/kg for optimum growth and mineralization of H. fossilis.  相似文献   

19.
Hypersalinity culture of marine shrimp can lead to poor growth and feed efficiency. This study evaluated the effect of dietary supplementation of three oil sources (krill, fish and soybean) on the growth of Litopenaeus vannamei reared under high salinity. Shrimp of 2.79 ± 0.60 g were reared for 64 days under isosmotic (ISO, 23 ± 1.2 g/L) and hyperosmotic (HOS, 44 ± 2.0 g/L) conditions. Diets varied in their fatty acid composition: Control, 35 g/kg of the diet (as fed basis) soybean oil; Fish, 27 g/kg fish oil and 10 g/kg soybean oil; Krill, 48 g/kg krill oil and 4 g/kg soybean oil; Krill‐, 15 g/kg krill oil and 21 g/kg soybean oil; Krill+, 55 g/kg krill oil and 4 g/kg soybean oil. At harvest, Krill diet promoted the fastest shrimp growth (1.01 ± 0.01 g/week) and body weight (11.97 ± 2.01 g), regardless of water salinity. There were no significant differences in shrimp survival (93.4 ± 5.07%) and yield (554 ± 68.5 g/m2) among different diets. Shrimp fed Fish, Krill and Krill+ had higher concentrations of PUFA compared to those fed Control and Krill‐ diets.  相似文献   

20.
The influence of dietary supplementation of Lactobacillus acidophilus, on growth performance, digestive enzyme activities, gut histomorphology and gut microflora were evaluated in juveniles striped catfish (Pangasianodon hypophthalmus). Five experimental diets were formulated by supplementing 0, 103, 105, 107 and 109 CFU/g L. acidophilus in fishmeal and casein‐based semi‐purified diet. Triplicate groups of striped catfish (21.69 ± 0.18 g) were stocked in 15 fiberglass tanks with stocking density of 25 individuals per tank and fed twice daily at 2.5% of the fish body weight for 12 weeks. Weight gain, specific growth rate, feed conversion ratio and the protein efficiency ratio were significantly higher in fish fed with 105 and 107CFU/g L. acidophilussupplemented diets compared with the other treatment groups. Compared with the control and fish fed low (103 CFU/g) L. acidophilus supplementation, those fed with 105 and 107 CFU/g had significantly higher (p < 0.05) apparent protein digestibility. Inclusion of L. acidophilus at 107 CFU/g diet significantly increased amylase, protease and lipase activities. Microscopic analysis showed that the villi length in both the anterior and posterior gut and microvilli length in the posterior gut increased significantly in fish fed L. acidophilus supplementation at 105 and 107 CFU/g of diet. The fish fed L. acidophilus supplemented diets significantly increased the total lactic acid bacteria counts in the gut of striped catfish compared with the control‐fed group. Based on gut histomorphology and growth performance, inclusion of L. acidophilus at 105 CFU/g appears to have the most positive effect on striped catfish farming.  相似文献   

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