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1.
Juvenile red drum Sciaenops ocellatus were tank-reared in two, separate 30-d trials to assess effects of total water hardness and chloride concentratlon on growth, survival, and feed conversion. Two levels of total hardness and chloride were used in 2 × 2 factorial designs to obtain total hardness and chloride levels in trial one of 100 and 200mg/L CaCO3 and 125 and 250mg/L Cl−, and hardness and chloride levels of 100 and 400mg/L CaCO3 and 150 and 500mg/L Cl− in trial two. In trial one, average daily growth and feed conversion were significantly ( P ≤ 0.05) improved at 100mg/L hardness levels compared to 200mg/L at both chloride levels. Average daily growth was 0.11 ± 0.02g/d at 100mg/L hardness and 125mg/L Cl− compared to 0.06 ± 0.01g/d at 200 mg/L hardness and 125mg/L chlorides. No significant ( P ≥ 0.05) difference in survival could be attributed to levels of total hardness or chloride. In trial two, 500 mg/L Cl− treatments produced significantly ( P ≤ 0.01) better growth, survival and feed conversion than 150mg/L Cl− at either level of total hardness (100 and 400mg/L). Survival at 150mg/L chloride and 100mg/L hardness was 48.8 ± 18.7%, while at 500mg/L chloride and 400mg/L hardness survival increased to 96.6 ± 2.1%. Growth also increased from 0.14 ± 0.03 to 0.27 ± 0.01g/d and feed conversion improved from 5.77 ± 1.56 to 1.87 ± 0.06 at the same levels. No interactions between levels of hardness or chlorides were shown to affect red drum growth, survival, or feed conversion in either trial.  相似文献   

2.
This investigation examined the effect of prey condition on the growth and survival of juvenile cuttlefish ( Sepia officinalis ). In the first group, cuttlefish were fed with daily captured live Palaeomonetes varians from the wild [daily prey (DP)], the second group was fed 5 days stocked and starved P. varians [starved prey (SP)], while in the third group, cuttlefish were fed 8 days stocked P. varians fed with an artificial diet [fed prey (FP)]. Mean instantaneous growth rate (IGR) was 2.8±1% body weight day−1 (bw day−1), 3.3±1.1% bw day−1 and 4.9±0.5% bw day−1 for SP, DP and FP respectively. At the end of the experiment, final weight gain ( W g) was 121±21.6%, 153.8±17.3% and 295±29.8% for SP, DP and FP respectively. No significant differences were found ( P >0.05) between growth curves for every group tested, or for the food conversions between those same groups ( P >0.05), but statistical differences ( P <0.05) were found in IGR between DP vs. FP and SP vs. FP. Mortality was 2 and 1 for SP and DP respectively. Results indicate that prey starvation should not be considered when feeding juvenile cuttlefish, as prey can only be stocked if proper artificial diets are provided, to obtain optimal growth.  相似文献   

3.
Three isolated marine diatoms ( Amphora , Navicula and Cymbella ) grown on substrate were evaluated as feed supplement for Penaeus monodon postlarvae (PL) in hatchery system for a period of 19 days without changing water. Specific growth rate (day−1) (0.27 ± 0.0) and survival (%) (56.3 ± 1.8) of PLs were significantly higher ( P  < 0.05) in treatment tanks when compared with the control (0.20 ± 0.0; 36.0 ± 1.5, respectively). Shrimp PLs reared in substrate-based tanks had significantly higher ( P  < 0.05) levels of protein, lipid (521.0 ± 7.0; 304.0 ± 2 g kg−1 dry weight, respectively), ecosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) (189.0 ± 2.0; 176.0 ± 2 g kg−1 of total fatty acid, respectively) than the control (435.0 ± 22.0; 258.0 ± 22 g kg−1 dry weight; 172.0 ± 5.0; 152 ± 2 g kg−1 total fatty acid, respectively). The periphytic diatoms contained protein and lipid (430–490; 230–260 g kg−1 dry weight, respectively), EPA (30–150 g kg−1 of total fatty acids), DHA (20–30 g kg−1 of total fatty acids) and nine essential amino acids. The results showed that isolated marine periphytic diatoms grown on substrate could be used as feed supplement in enhancing the growth and survival of P. monodon postlarvae.  相似文献   

4.
Juvenile Haliotis rufescens were reared in the laboratory in order to investigate the extent to which fresh kelp and formulated feeds with 250 g kg−1 (25P) and 380 g kg−1 protein content (38P) affected their growth rate, gut residence time (GRT), food consumption ( C ), food conversion ratio (FCR) and digestibility. Abalone from 38P attained the highest growth rate (70.5 ± 4.2 μm day−1; 98.3 ± 6.95 μg day−1), followed by 25P (47.9 ± 2.79 μm day−1; 67.4 ± 2.82 μg day−1) and kelp (23.6 ± 3.36 μm day−1; 28.2 ± 4.11 μg day−1). No significant differences were observed in consumption rate among treatments (0.61–0.68% body weight per day), yet kelp-fed abalone exhibited higher FCR (2.44), protein efficiency ratio (4.42), and apparent digestibility of dry matter (69.5%), protein (69.8%) and gross energy (79.2%) than 38P organisms (59.8, 62.4 and 62.2%, respectively). They also showed longer GRT (23.1 ± 0.93 h). This study demonstrated that formulated diets with 250 g kg−1 and 380 g kg−1 protein inclusion can sustain higher growth rates of juvenile H. rufescens than fresh algae. These differences seem to be due to the amount of dietary protein. Kelp meal appears to improve the consumption and digestibility of balanced diets, and its inclusion in formulated diets is recommended.  相似文献   

5.
Broodstock pacu Piaractus brachypomus as well as their eggs during their embryonic development were exposed to either normoxia (5.5–7.5 mg O2/L) or hypoxia (2.0–4.5 mg O2/L) conditions. The plasma concentrations of 11-ketotestosterone in males and estradiol-17β in females, as well as that of their precursor testosterone (T) were significantly ( P < 0.01) higher in fish maintained under normoxic conditions than in fish exposed to hypoxia. After ovulation and spermiation induced by hormonal treatments, the plasma concentrations of T and 17,20β-dihydroxy-4-pregnen-3-one (17,20βP) significantly ( P 0.05) increased in both sexes under both normoxic and hypoxic conditions. The plasma levels of T and 17,20βP achieved under normoxic conditions were higher than the ones recorded under hypoxia, except for those of 17,20βP in males. Males responded positively to the hormonal treatments, and the concentration of spermatozoa was 10.5 ± 0.8 109/mL under both oxygen conditions. Hypoxia resulted in significantly lower survival of embryos (17.3 ± 28%) in comparison to normoxic conditions (68.5 ± 25%). Moreover, larval deformities were found when exposed to hypoxia (91.6 ± 6%). During embryonic development of this species 4 mg/L of oxygen is tolerated at 26–27 C without negative impact. We conclude that despite the highly adaptable nature of adult pacu to environmental hypoxia, oxygen concentrations below 4 mg/L severely impacted survival of embryos.  相似文献   

6.
Kappaphycus alvarezii was cultivated at three places, viz. Mithapur, Okha and Beyt Dwarka on the Northwest coast of India. The biomass and growth rates were measured at 15-day intervals up to 45 days and varied differently for different growth periods at these places. Thus, at 15, 30 and 45 days, the biomass (fresh wt) varied from 182.0±19.96 to 435.0±23.66 g, from 366.0±118.09 to 1096.0±61.43 g and from 530.5±50.95 to 1537.0±43.54 g, respectively, with respective daily growth rates (%) from 3.95±0.78 to 9.80±0.63, from 3.64±0.01 to 13.98±3.07 and from 3.69±0.23 to 6.07±0.06. The seawater temperature, salinity, nitrate and phosphate ranged from 19.3 to 26.9 °C, from 30.81 to 36.83‰, from 11.60 to 19.75 μmol L−1 and from 2.37 to 5.0 μmol L−1 respectively. The growth rate between the culture months was significantly different at Okha at P <0.01. Further, it was significantly correlated to salinity at Mithapur while at Okha and Beyt Dwarka, the same was significantly correlated to nitrate and seawater temperature. Based on this study, commercial cultivation at these localities is quite feasible.  相似文献   

7.
The optimum feeding rate of the rotifer Bruchionus plicutilis was investigated to determine the best conditions for growth of the rotifer, and also in order to maintain good water quality of the culture. Fifty rotifers of a large size strain were cultured individually at five food density levels of Nannoehloropsis sp. (0.5 ± 106, 1.5 ± 106, 3 ± 106, 5 ± 106, and 8 ± 106 cells/ml). At each level, daily survival and offspring production were recorded until the death of the final individual. The data obtained were analyzed by the life table method. The maximum value of three growth indices (the net reproduction rate, mean life expectancy at age 0, and intrinsic rate of increase) was obtdned at the food density of 1.5 ± 106 cells/ml. The ration size was calculated to be 325% (dry weight)/ day, which is equivalent to about 70% of the saturated feeding rate. It was suggested that the feeding rate should be controlled to lower than the saturated value for an efficient mass culture.  相似文献   

8.
Live adult brine shrimp, Artemia franciscana (Latreille), were enriched with erythromycin to determine if Artemia could accumulate therapeutic levels for subsequent feeding to young fish. Three trials were conducted to determine the erythromycin incorporation and survival rates of enriched Artemia when fed either liposomes containing erythromycin or various erythromycin suspensions. Erythromycin concentration in Artemia fed a liposome suspension was low (∼ 5 μg mL−1) relative to Artemia fed the direct suspension (> 100 μg mL−1) over the same time period. When enriched with suspensions up to 1 g erythromycin L−1 sea water for 14 h, Artemia survival was not significantly affected ( P > 0.05) relative to controls. Using a suspension of 1 g L−1, tissue erythromycin concentrations of 109 ± 16 μg erythromycin mL−1  Artemia homogenate (mean ± SEM) were achieved after 12 h. Concentrations above 170 μg mL−1 were obtained using suspensions of 2–5 g L−1, but Artemia survival significantly ( P < 0.05) decreased.  相似文献   

9.
ABSTRACT:   The effectiveness on water quality, population density of bacteria, and shrimp production in ponds treated with commercial probiotics was tested in Penaeus vannamei ponds in Hai-yan, China. Six ponds with replicates for treatment and control were used. Results showed that the probiotics could improve the population density of beneficial bacterial flora, reduce concentrations of nitrogen and phosphorus, and increase yields of shrimp. The average counts of Bacillus sp., ammonifying bacteria, and protein mineralizing bacteria were found to be significantly higher in treated ponds compared to control ponds ( P  < 0.05). In control ponds, an increase in presumptive vibrios was observed and the average density was up to 2.09 × 103 cfu/mL, whereas that was only 4.37 × 102 cfu/mL in treated ponds ( P  < 0.05). The use of probiotics also significantly increased dissolved oxygen ( P  < 0.05) and reduced dissolved reactive-phosphorus, total inorganic nitrogen and chemical oxygen demand ( P  < 0.05). An average of 8215 ± 265 kg shrimp/ha was obtained in treated ponds with a feed conversion ratio (FCR) of 1.13 ± 0.05 and survival rate of 81.00 ± 6.25% compared with 4985 ± 503 kg shrimp/ha, 1.35 ± 0.12 and 48.67 ± 3.51%, respectively, in control ponds. This indicates that the addition of the commercial probiotics had a noticeable influence on water quality of shrimp ponds and shrimp production.  相似文献   

10.
Juvenile northern Chilean scallops of 937±55 μm shell height were exposed to five different concentrations of chloramphenicol (CHL) (5, 10, 25, 50 and 100 μg mL−1), plus a control without antibiotics. To determine the effect of CHL on the accompanying microflora, the number of colony-forming units (CFU) that grew on TGE culture medium was counted in the seawater of containers with juveniles, and in containers with microalgae used as food. Both were exposed to the same concentrations of CHL. The growth rates of juveniles treated with CHL and the control without antibiotic showed highly significant differences ( P =0.0001). The growth rate was inversely proportional to the CHL concentration. The control sample presented the highest growth rate (84.4±14.3 μm day−1), followed by the sample treated with 5 μg mL−1 (64.2±14.3 μm day−1). The survival in the control and in the treated samples with 5–50 μg mL−1 was rather high, with a mean value of 95%. Only the sample treated with 100 μg mL−1 had a low survival (36.7%). The CFU count was larger in the containers with juveniles, when compared with the ones with food. The CFU count tended to decrease with increasing CHL concentration in the juveniles.  相似文献   

11.
Reference (physiological) value intervals determined by the lower 2.5% and upper 97.5% quantiles were calculated for total calcium (Ca t ) and inorganic phosphate (P) in farmed rainbow trout, Oncorhynchus mykiss , at an age of 10–12 months in raceway culture. Total calcium levels were significantly ( P ≤0.0009) greater in males (2.63–4 mmol L−1, n =47, mean weight 359±142 g) than in immature females (2.48–3.97 mmol L−1, n =410, mean weight 400±145 g). The reference range for P in immature females and males was 3.09–9.32 mmol L−1 ( n =467, mean weight 401±144 g). The distribution and density of the quantiles in the tested reference group were made possible by the use of histograms, which showed normal distributions for Ca t in males but not for Ca t and P in immature females and males, in which a sinistral asymmetry was found.  相似文献   

12.
Abstract  Brown trout, Salmo trutta L., spawning sites were constructed by creating areas of artificial upwelling water, 252 ± 37 mL m−2 min−1 (95% CL), through appropriately sized spawning gravel substrate in 3 m2 vessels buried in the bottom of a 150-m2 pond. Natural spawning occurred in the vessels during autumn 2001–2004, with hatching and alevin swim up the following spring. In areas of upwelling, egg survival was 85–95%, while no live eggs were observed in areas without upwelling. In areas with upwelling, the maximum density of live eggs at the eyed stage was 570–1510 eggs m−2. In spring 2004 and 2005, the density of alevins was estimated at 322 (±187) m−2 and 567 (±217) m−2, respectively, in areas with upwelling water, compared with 35.2 ± 25.4 m−2 in areas without upwelling water in 2004.  相似文献   

13.
Growth, survival, tissue ascorbate concentration and collagen content were studied in fast-growing Penaeus monodon fed two ascorbic acid (AA) derivatives. Prior to the experimental trial, shrimp (initial body weight: 0.9 ± 0.4 g) were fed on a diet lacking vitamin C for 5 weeks. During the following 13-week experiment, the shrimp (initial body weight: 8.2 ± 0.7 g) were given one of five squid-meal-based diets. The dietary treatments consisted of a diet lacking vitamin C, two diets supplemented with either 500 or 1000 mg AA kg−1 in the form of silicone-coated AA, and two diets supplemented with either 500 or 1000 mg AA kg−1 in the form of ascorbyl-2-polyphosphate. Shrimp gained 18.3 g in 13 weeks. The AA-free diet group exhibited the lowest growth rate, feed intake and survival (26.8%) after 4 weeks. Hepatopancreatic ascorbate and muscle collagen content were significantly ( P < 0.05) lower in AA-deprived shrimp. At the end of the feeding trial, growth rate and survival were not significantly ( P > 0.05) different among groups fed AA-supplemented diets. Hepatopancreatic and haemolymphatic ascorbate concentrations were significantly ( P < 0.05) higher in groups given ascorbyl-2-polyphosphate than in groups given silicone-coated AA. A supplement of 500 mg AA kg−1 diet in the form of either silicone-coated AA or ascorbyl-2-polyphosphate was adequate for optimal growth. But ascorbate concentrations in tissues remained much below saturation levels with a supplement of 1000 mg AA kg−1 diet. It is questionable whether the established vitamin C requirements for P. monodon are adequate to maintain tissue ascorbate in fast-growing juveniles.  相似文献   

14.
Recirculating raceway systems were examined for their potential as a method for the intensive culture of the marine shrimp Penaeus vannamei Boone. The systems consisted of fiberglass raceways 38 m3 (13.7 m ± 2.4 m ± 1.16 m) and 28 m3 (13.7 m ± 2.4 m ± 0.85 m) each equipped with a vertical screen biofilter, foam fractionators and an ultraviolet ozone generator. All of the systems were enclosed in a commercial greenhouse. Four preliminary growout experiments and two growout experiments with stocking densities of 970 shrimp/m3 and 2,132 shrimp/m3 were completed.
Temperature, pH and salinity remained constant throughout the experiments. Unionized ammonia levels remained below 0.2 mg/L. Nitrite levels ranged from 0.1 to 1.0 mg/L. The 2,132/m2 stocking density resulted in 48% survival, food conversion ratio (FCR) of 1.8 and an average size of 10.8 g. The 970/m3 stocking density resulted in 82% survival, FCR of 2, and an average size of 14 g. Production was 11.4 kg/m3 (114 tons/ha) and 11.0 kg/m3 (110 tons/ha) for the high and low stocking densities, respectively.  相似文献   

15.
The study aims to test whether predigested dietary protein enhances the utilization of formulated diets at weaning, and also whether it stimulates intestinal maturation. In this study, Atlantic cod [ Gadus morhua L.; 41 days posthatch (dph)] and Atlantic halibut [ Hippoglossus hippoglossus L.; 63 days postfirst feeding (dpff)] were weaned onto diets with graded levels of protein hydrolysate. By increasing the inclusion of dietary protein as hydrolysate from 0 to 400 g kg−1, cod increased the rate of survival from 7 ± 1% to 18 ± 2% (82 dph; regression, P =  4*10−7). In halibut, the survival rate decreased from 57 ± 9% to 22 ± 7% as the inclusion of protein in the form of hydrolysate increased from 0 to 450 g kg−1 (119 dpff; regression, P =  8*10−5). Growth was not affected in any of the species. Results in specific activities of the intestinal enzymes leucine aminopeptidase (LAP) and alkaline phospatase (AP) supported the results in survival in halibut and partly also in cod, by showing increased activities in groups with increased survival ( anova , P <  0.05). The lower optimal level of hydrolysed protein in halibut than in cod is suggested mainly because of a slower feeding practice in halibut, which allows more extensive nutrient leaching before ingestion.  相似文献   

16.
The study was conducted to investigate the effects of dietary Chlorella powder (C) supplementation on growth performance, blood characteristics, and whole-body composition in juvenile Japanese flounder Paralichthys olivaceus . Four experimental diets were supplemented with C at 0, 1, 2 and 4% (C0, C1, C2, and C4) on a dry-weight basis. Three replicate groups of fish averaging 1.13 ± 0.02 g (Mean ± SD) were randomly distributed in each aquarium and fed one of four experimental diets for 12 wk. After 12 wk of the feeding trial, fish fed C2 diet had higher weight gain (WG), feed efficiency (FE), and protein efficiency ratio (PER) than did fish fed C0 and C1 diets ( P 0.05); however, there was no significant difference among fish fed C1 and C4 diets, and among fish fed C2 and C4 diets ( P > 0.05). Fish fed C2 and C4 diets had a lower serum cholesterol level than did fish fed C0 and C1 diets ( P 0.05). Fish fed C2 and C4 diets had a lower body fat than did fish fed C0 ( P 0.05). These results indicate that dietary supplementation of 2% Chlorella powder in the commercial diets could improve growth, feed utilization, serum cholesterol level, and whole-body fat contents in juvenile Japanese flounder.  相似文献   

17.
This investigation examined the effects of temperature, density and early weaning on the survival and growth of Palaemonetes varians larvae. Survival of larvae raised at 17.5 °C was not significantly different (average + standard deviation) (94 ± 5%) from the survival of those raised at 19.5 °C (95 ± 5%) and at 21.5 °C (94 ± 4%). However, the duration of the larval stage was significantly longer for shrimp reared at 17.5 °C (17.3 ± 0.8 days) compared with shrimp reared at 19.5 °C (14.3 ± 0.7 days) and at 21.5 °C (11.3 ± 0.6 days). No significant differences ( P >0.05) were found in the survival rate, final weight and length of larvae reared at the densities of 5, 10, 20 and 50 larvae L−1. The survival of P. varians larvae fed solely on Artemia was significantly higher ( P <0.05) than larvae weaned with an artificial practical diet from Zoea II stage (94 ± 4% and 82 ± 1%, respectively, for Artemia and artificial diet-fed larvae), but no significant differences ( P >0.05) were observed in the final larval weight or length between these two treatments. The survival and growth of the larvae fed with the practical diet tested is a promising step ahead in the development of the culture of this species as it eliminates both the need for Artemia throughout all larval stages, and the need for more expensive artificial diets.  相似文献   

18.
Pond water quality and associated microbial biomass were studied in relation to the type of feed applied during the culture of the marine shrimp Penaeus vannamei . The feeds tested included conventional feedlot manure as well as two feeds based on bagasse, a sugarcane waste product. Physical and chemical parameters were studied during a 100 day trial in 200 m2 earthen ponds. Both bagasse-based feeds supported a significantly larger microbial community as measured by specific biomass numbers ( P < 0.01), ATP content ( P < 0.001) and amount of the particulate organic matter present on pond bottoms ( P < 0.025). For both bagasse-based treatments, the estimated bacterial cell number in the flocculent layer was 3.11 ± 1012/m2, compared to the much lower cell number of 7.53 ± 1010/m2 for control ponds. Harvest data suggest that bagasse forms a potential base for feeds when applied to extensive shrimp cultures.  相似文献   

19.
Triploid hybrid saugeyes may be a desirable stocking alternative because diploid saugeyes are fertile and can compromise the genetic integrity of parental stocks. Four groups of saugeye eggs were heat-shocked 5 min after fertilization for 15 min at 31 °C, which resulted in an 86.7 ± 9.4% triploidy rate and 57.8 ± 24.3% survival to the eyed-stage. Heat shocked and control saugeyes were stocked in two ponds for 40 days at 395 000 ind. ha–1. Mean length and weight of triploid and heat-shocked diploid saugeyes were greater ( P  < 0.01) than unshocked diploid saugeyes. Survival of heat-shocked saugeyes (22.4%) was lower than unshocked saugeyes (94.7%). Heat-shocked fish ( n =25 851) harvested from ponds were stocked for 153 days in O'Shaughnessy Reservoir, Ohio, USA. Triploids were 34 mm shorter and weighed 41 g less than heat-shocked diploids ( P  < 0.01). Mean length and weight of triploids were comparable with unshocked diploids elsewhere in Ohio.  相似文献   

20.
Nursery production may be enhanced by the addition of artificial substrate to increase the surface area upon which shrimp graze and to serve as refuge. The objective of this study was to assess the effects of the artificial substrate, AquaMatsTM, on the performance of postlarval Pacific white shrimp Litopenaeus vannamei stocked at three densities. Eighteen 230-L tanks were stocked with 10-d postlarvae (mean weight < 0.01 g). Six treatments were evaluated and consisted of shrimp stocked at three densities (778 shrimp/m2, 1,167 shrimp/ m2, and 1,556 shrimp/m2) with and without access to artificial substrate. Shrimp in all treatments received a commercial diet ad libitum . After 6 wk, shrimp were harvested from each nursery tank, counted, and batch weighed. Mean final weight, survival, production, feed conversion ratio, and water quality parameters were analyzed by 2-way ANOVA. There were highly significant ( P < 0.001) density and substrate effects on final weight, but there was no significant interaction effect. Final weight was 26.0, 17.4, and 34.5% greater in treatments with substrate than without substrate when stocked at 778, 1,167, and 1,556 shrimp/m2, respectively. There was no significant density, substrate, or interaction effect on survival or water quality. Mean survival was ± 89.1% for all treatments. Increased shrimp growth in the presence of added substrate was likely due to the availability of attached particulate organic matter on the AquaMatsTM that served as an additional food source. Results from this study indicate that artificial substrate can be used to mitigate the potential negative effects of high stocking density on growth of L. vannamei in nursery systems.  相似文献   

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