首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献，搜索用时 31 毫秒
1.
The aim of this study was to evaluate the effect of the addition of Navicula spp. and Brachionus plicatilis on water quality and growth of postlarvae shrimp Litopenaeus vannamei reared in a biofloc system. Four treatments were considered: a control (biofloc system – BFT); BFT with the addition of Navicula spp. (BFT‐N); BFT with the addition of Brachionus plicatilis (BFT‐B) and BFT with the addition of Navicula spp. and Brachionus plicatilis (BFT‐NB), each in triplicate. Shrimp (16.2 ± 0.03 mg) were stocked at a density of 2500 shrimp m?3 and plankton were added on days 1, 5, 10, 15, 20, 25 and 30 at a density of 5 × 104 cells mL?1 (Navicula spp.) and 30 organisms L?1 (Brachionus plicatilis). The shrimp were fed a formulated feed in four daily rations composed of 40% crude protein and 8% lipids. Significant differences between treatments were observed for final weight, yield, feed conversion ratio, specific growth rate, protein efficiency ratio and protein content of the shrimp. The combined plankton addition of Navicula spp. and B. plicatilis had better performance parameters, indicating their benefit as natural food sources for postlarvae L. vannamei in biofloc systems.  相似文献   

2.
Effect of different carbon sources on nursery performance of Pacific white shrimp (Litopenaeus vannamei) cultivated in biofloc system was investigated. Shrimp postlarvae (98.47 ± 8.6 mg) were fed for 32 days in tanks with water volume of 130 L and density of 1 individual L?1. One control treatment and four biofloc treatments (BFT1, BFT2, BFT3 and BFT4) with adding different carbon sources including molasses, starch, wheat flour and mixture of them, respectively, were considered at equal weight ratios. According to the results, salinity, dissolved oxygen and pH were not significantly different among the biofloc treatments (P > 0.05). Maximum pH (8.27) and maximum dissolved oxygen (6.35 mg L?1) were recorded in the control. Maximum (0.43 mg L?1) and minimum (0.09 mg L?1) ammonia were recorded in the control and BFT2, respectively (P < 0.05). Using simple carbohydrates (molasses and starch) lowered the ammonia concentration significantly. The highest increase in body weight (1640.43 ± 231.28 mg), growth rate, specific growth rate (8.97 ± 0.42% per day) and biomass (190.29 ± 26.83 mg) were found in BFT1 and the highest survival (90 ± 0.77%) was found in BFT4. The highest feed conversion (1.52 ± 0.23) and the lowest feed efficiency (66.81 ± 7.95) were observed in the control (P < 0.05). The proximate composition analysis revealed an increase in lipid and ash in biofloc treatments. Results indicated that using biofloc technology with zero‐water exchange system and adding carbon sources could help to recycle waste and improve the water quality. Moreover, the type of carbonaceous organic matter as a substrate for heterotrophic bacteria would be effective in degradation and metabolization of ammonia and nitrite.  相似文献   

3.
The aim of this study was to evaluate the effect of the addition of Chaetoceros calcitrans, Navicula sp. and Phaeodactylum tricornutum (diatoms) on phytoplankton composition and the growth of Litopenaeus vannamei postlarvae reared in a biofloc system . Four treatments were used: BFT (biofloc system without feed and no addition of diatoms); BFT‐F (biofloc system with feed and no addition of diatoms); BFT‐D (biofloc system with the addition of diatoms and no feed); and BFT‐FD (biofloc system with the addition of feed and diatoms), all in triplicate. The shrimp (16 ± 0.02 mg) were stocked at 2500 postlarvae m?3 and fed a commercial feed. Diatoms were added on the 1st, 5th, 10th and 15th day at a density of 5 × 104 cells mL?1 for each species. No significant differences (P > 0.05) between treatments were observed for gross primary production, net ecosystem production and water column respiration rate. However, significant differences (P < 0.05) were observed for nitrite, orthophosphate, alkalinity, final weight, weight gain, yield, feed conversion ratio (FCR), phytoplankton and cyanobacteria composition. The BFT‐FD treatment had better performance parameters for final weight (270 mg), weight gain (254 mg), yield (0.67 Kg m?3) and FCR (0.61), indicating the benefits of the diatoms C. calcitrans, Navicula sp. and P. tricornutum for decreasing cyanobacteria and improving growth of L. vannamei postlarvae reared in biofloc systems.  相似文献   

4.
This study evaluated the zootechnical performance and enzymatic activity of Litopenaeus vannamei reared at different feeding frequencies during the nursery phase in biofloc system. The experiment consisted of four treatments, corresponding to the feeding frequencies of one, two, three and four times a day. Twelve‐day postlarvae (PL12) were stocked in 12 circular tanks at a density of 3,000/m2 for 35 days. These tanks were connected to a recirculation system supplied by a matrix tank where biofloc management was carried out. Water quality remained within acceptable limits for the species over the experiment. Food frequencies had no influence on survival (88.5–92.7%) and feed conversion ratio (1.5–1.7), but the final mean weight (0.43–0.56 g) was significantly higher in shrimp fed three times a day. This fact is probably associated with amylase (14.58 U/mg) and trypsin (23.84 U/mg) activities, as well as the significant increase of chymotrypsin (11.74 U/mg) and lipase (1.27 U/mg) in shrimp of this treatment at the end of culture period. Feeding three times a day provided the highest enzymatic activity and the best zootechnical performance of L. vannamei during the nursery phase in biofloc system.  相似文献   

5.
A feeding trial was carried out to determine the effects of bioflocs on dietary protein requirement in juvenile whiteleg shrimp, Litopenaeus vannamei. Four bioflocs treatments (BFT) and one control group were managed: BFT fed diets 25% of crude protein (CP) (BFT‐25%), 30% CP (BFT‐30%), 35% CP (BFT‐35%) and 40% CP (BFT‐40%), and clear water control without bioflocs fed with 40% CP (CW‐40%). Triplicate groups of shrimp (initial body weight, 1.3 g) were fed one of the test diets at a ratio of 7% body weight daily for 8 weeks. At the end of the feeding trial, significantly (P < 0.05) higher weight gain and specific growth rate were obtained in shrimp fed BFT‐35% and BFT‐40% compared to BFT‐25% and BFT‐30%. Shrimp fed BFT‐35% exhibited the lowest feed conversion ratio. Significantly higher muscle nucleic acid indices were also recorded such as DNA content in BFT‐30%, RNA content in BFT‐35% and RNA/DNA ratio than that of shrimp fed control. Total protein level in the haemolymph of shrimp fed BFT‐40% was significantly higher than those of shrimp fed BFT‐25% and BFT‐30%. Therefore, the present results demonstrated that, when L. vannamei juveniles were reared in bioflocs‐based tanks, dietary protein level could be reduced from 40% to 35% without any adverse effect on shrimp growth performance, body composition and haemolymph characteristics. [Correction added on 20 May 2015, after first online publication: sentence modified to clarify the reduction in dietary protein level.].  相似文献   

6.
The current study evaluates the efficacy of a low‐cost salt mixture (LCSM) to replace expensive reconstituted sea salt (RSS) in the salinity acclimation and nursery phase of Pacific white shrimp under laboratory and farm conditions. LCSM was formulated to yield sodium, potassium, calcium and magnesium concentrations closely comparable to that of diluted seawater. Laboratory‐based nursery trials were conducted at 2, 6 and 15 g/L salinities, incrementally replacing RSS with LCSM (25%, 50%, 75% and 100%) at four replicates per treatment. Thirty postlarvae were reared for 7 days in 24‐L aquaria during the 2 and 6 g/L trials, while the nursery trial for 15 g/L salinity was conducted for 21 days with 400 postlarvae stocked in 150‐L tanks. On‐farm evaluation of LCSM was carried out in two tank‐based systems installed on levees adjacent to shrimp production ponds. RSS was incrementally replaced with LCSM (0%, 50%, 75% and 100%) and 100 postlarvae stocked into each 800‐L tank. Salinity acclimation was done from 30 g/L to 6 or 1.5 g/L within 2–3 days by pumping water from adjacent shrimp production ponds. Following salinity acclimation, the S4 system maintained flow‐through at 1.5 g/L, while N10 system was maintained static at 6 g/L salinity. At the conclusion, no significant differences were observed for either survival or growth of shrimp postlarvae between RSS and LCSM treatments at all salinities examined. Results reflect the potential use of LCSM to replace RSS, which could be an excellent solution to bring down the cost of production in inland shrimp aquaculture.  相似文献   

7.
Litopenaeus vannamei (Boone) grown in ponds are exposed to salinities of less than 5 g L?1 during inland shrimp culture or to more than 40 g L?1 from evaporation and reduced water exchange in dry, hot climates. However, dietary requirements for shrimp grown in low or high salinities are not well defined, particularly for fatty acids. Feeding shrimp postlarvae with highly unsaturated fatty acids (HUFA) enhances tolerance to acute exposure to low salinity, as a result of better nutritional status, or/and specific effects of HUFA on membrane function and osmoregulation mechanisms. This study analysed the effect of HUFA supplementation (3% vs. 34%) on L. vannamei juveniles reared for 21 days at low (5 g L?1), medium (30 g L?1) and high salinities (50 g L?1). Juveniles grown at 5 g L?1 had lower survival compared with controls (30 g L?1) or shrimp grown at 50 g L?1, but no significant effect on survival was observed as a result of HUFA enrichment. In contrast, growth was significantly lower for shrimp grown at 50 g L?1, but this effect was compensated by the HUFA‐enriched diet. Osmotic pressure in haemolymph was affected by salinity, but not by HUFA enrichment. Shrimp fed HUFA‐enriched diets had significantly higher levels of eicosapentaenoic acid and docosahexaenoic acid in hepatopancreas and gills. These results demonstrate that growth at high salinities is enhanced with diets containing high HUFA levels, but that HUFA‐enriched diets have no effect on shrimp reared at low salinities.  相似文献   

8.
The objective of this study was to evaluate the effect of the addition of Navicula sp. on the growth and fatty acids profile of Litopenaeus vannamei postlarvae in a biofloc system (BFT). Four treatments were used: BFT; BFT 2.5N (addition of 2.5 × 104 cells/ml of Navicula sp.); BFT 5N (addition of 5 × 104 cells/ml of Navicula sp.) and BFT 10N (addition of 10 × 104 cells/ml of Navicula sp.), all in triplicate. The shrimp (1 ± 0.01 mg) were stocked at a density of 3,000 postlarvae/m3 and fed with commercial feed. The diatom was added every 10 days, and at the end of 42 days, shrimp performance, water quality and proximal composition were evaluated. The BFT 5N and BFT 10N treatments had higher performance values, highlighting the values of productivity (2.30 and 2.42 kg/m3) and specific growth rate (15.92 and 16.08%/day), which were higher than the other treatments. In addition, the highest levels of fatty acids were observed in treatments with diatom (BFT 5N and BFT 10N), indicating the benefits of Navicula sp. on growth enhancement and fatty acid content of L. vannamei postlarvae grown in biofloc systems.  相似文献   

9.
The tolerance of postlarval Macrobrachium rosenbergii to gradual and rapid increases in salinity was determined. Mortalities occurred at salinities around 25‰ and increased rapidly at levels ≥30‰ in both cases. However, acclimation substantially increased survival time at 35‰.Freezing point depressions of blood were measured from laboratory-reared M. rosenbergii postlarvae and juveniles exposed to various salinities from fresh water to approximately 35‰. The blood concentration was hyperosmotic to the medium at salinities from fresh water to about 17–18‰ and hypoosmotic at higher salinities. Postlarvae maintained a nearly constant blood concentration (freezing point depression = ?0.89 ± 0.13°C) over a wide range of external salinities (fresh water to about 27–30‰). The animals' osmoregulatory mechanisms failed at salinities ≥30‰, and thereafter the blood concentration paralleled that of the medium. The blood concentrations of juvenile shrimp grown for 5 months at salinities from fresh water to about 15‰ (freezing point depression = ?0.88 ± 0.07°C) closely resembled those of postlarvae.The osmoregulatory performance of young M. rosenbergii is generally similar to that of other brackishwater animals, but in their ability to hyperosmoregulate effectively in fresh water they more closely resemble fresh water species. It is suggested that M. rosenbergii may be able to conserve salt in dilute media by producing blood-hypoosmotic urine.An interesting stress symptom often preceded death of postlarvae in high salinities. The animals changed gradually from nearly transparent to opaque white and then died, usually within a day or so.  相似文献   

10.
Biofloc rearing media provides a potential food source for shrimp reared in limited or zero water exchange systems. This culture system is environmentally friendly as it is based on limited water use and minimal effluent is released into the surrounding environment. In this study, we evaluated the survival, growth performance and salinity stress tolerance of pink shrimp Farfantepenaeus paulensis postlarvae reared from PL10 to PL25 in a biofloc technology limited water exchange system. PL (mean ± SD weight and length of 14 ± 10 mg and 8.10 ± 0.7 mm, respectively) were reared in nine 40-L plastic tanks with a stocking density of 10PL/L. Three culture treatments were applied (1) culture in the presence of bioflocs and commercial feed supply (FLOC + CF); (2) culture in the presence of biofloc without feed supply (FLOC) and (3) culture in clear water with feed supply (control). Final biomass and survival were significantly higher in FLOC + CF treatment than the control (P < 0.05), but did not differ from FLOC. PL reared in the FLOC + CF treatment achieved a significantly higher final weight, weight gain and length in comparison with the other two treatments (P < 0.05). No significant difference (P > 0.05) between treatments was found for salinity tolerance over 24 and 48 h durations. The proximate analysis of floc shown high levels of crude protein (30.4%), but low levels of crude lipids (0.5%). The continuous availability of bioflocs had a significant effect on growth and survival of F. paulensis postlarvae cultured in BFT nursery systems.  相似文献   

11.
A 28-day indoor trial was conducted to evaluate the water quality, phytoplankton composition and growth of Litopenaeus vannamei in an integrated biofloc system with Gracilaria birdiae and Gracilaria domingensis. The experimental design was completely randomized with three treatments: control (shrimp monoculture); SB (shrimp and G. birdiae) and SD (shrimp and G. domingensis), all with three replicates. Random sampling was done (6 % of total population per experimental unit) to confirm white spot syndrome Virus (WSSV) infection using nested-PCR analysis due to suspicion of presence of the virus in the experiment (treatment and control groups). Shrimp L. vannamei (2.63 ± 0.10 g) were stocked in experimental tanks at a density of 425 shrimp m?3, and the Gracilaria was stocked at a biomass of 2.0 kg m?3. Shrimp mortality began in both the experimental and control groups at 10 days of culture. The integrated biofloc system (shrimp and seaweed) increased settleable solids (by 26–52 %); final weight (by 6–21 %); weekly growth (by 17–43 %); weight gain (by 17–43 %); specific growth rate (by 16–36 %); and yield (by 5–7 %) and decreased feed conversion ratio (by 21–28 %) and Cyanobacteria density about 16 % as compared to the control (shrimp monoculture). The use of red seaweed Gracilaria in an integrated biofloc system can enhance shrimp growth and reduce Cyanobacteria density in the presence of WSSV.  相似文献   

12.
The initial stages of rearing marine shrimp using biofloc technology (BFT) involve the biofloc formation process. At the same time, there is an increase in the levels of total suspended solids and a decrease in alkalinity and pH. This reduction of alkalinity and pH occurs due to the consumption of inorganic carbon by the autotrophic bacteria present in the bioflocs and biofilms. The aim of this study was to evaluate the effects of different alkalinities on water quality and the zootechnical performance of the marine shrimp Litopenaeus vannamei in a BFT system. The experiment consisted of four treatments, with three replicates each: 75, 150, 225 and 300 mg CaCO3/L. To maintain the alkalinity at the established level, sodium bicarbonate was applied. For the experiments, twelve experimental units (area = 0.20 m2) with an effective volume of 50 L were stocked with 30 juvenile L. vannamei (0.20 ± 0.07 g), to achieve a stocking density of 150 shrimps/m2 and were maintained for an experimental period of 49 days. The 75 treatment presented the highest levels of ammonia and nitrite throughout the study, compared to the 150 and 300 treatments. The results showed that higher alkalinity favors biofloc formation and the establishment of nitrifying bacteria.  相似文献   

13.
The rate of metamorphosis of larvae, duration of larval stages and carapace lengths of postlarvae were measured in the common prawn, Palaemon serratus, reared in 30 different combinations of temperature and salinity. Temperature varied from 13°C to 29°C and salinity from 13‰ to 43‰. When salinity.was 13‰, this species was able to metamorphose at a temperature of 21°C. For salinities of 19‰, 25‰, 31‰, 37‰ and 43‰, the temperature range over which metamorphosis occurs extends from 17°C to 25°C. The equation of Van't Hoff can be adapted to calculate the relation between the rearing rate, which is the converse of the duration of larval stages, and the water temperature. The Q10 values vary from 1.39 minimum at a salinity of 37‰ to 2.28 maximum at 31‰. Neither the effect of temperature (at 0.1%) nor that of salinity (at 1%) is significant for the carapace lengths of postlarvae.Tridimensional models of the combined effects of temperature and salinity on the rate of metamorphosis and on the number of metamorphosed postlarvae appearing daily were constructed for this species.  相似文献   

14.
ABSTRACT

Litopenaeus vannamei postlarvae were exposed to 0, 6, 13, and 19 mg/L total ammonia nitrogen (TAN) treatments. After 45 days, shrimp weight and length were lowest under TAN concentrations of 13 and 19 mg/L (P ≤ 0.05). Maximum weight gain was observed in control and 6 mg/L treatments. Mortality was highest (80.55 ± 4.80%) under 19 mg/L reared in 35 ppt salinity. Average intermolt periods of PLs exposed to 0, 6, 13, and 19 mg/L TAN were 11.5 ± 0.7, 10.8 ± 1.3, 9.4 ± 1.0, and 8.7 ± 0.6 days under 35 ppt and 11.1 ± 0.5, 10.7 ± 0.6, 10.1 ± 0.5, and 9.5 ± 0.2 days under 45 ppt salinity. Although TAN increased postlarvae molting frequency, its negative effects on the shrimp growth and survival of PLs was directly linked to its concentration and exposure duration. Higher salinity reduces the effects of ammonia and increases the survival.  相似文献   

15.
The bioflocs technology (BFT) for shrimp production has been proposed as a sustainable practice capable of reducing environmental impacts and preventing pathogen introduction. The microbial community associated with BFT not only detoxifies nutrients, but also can improve feed utilization and animal growth. Biofloc system contains abundant number of bacteria of which cell wall consists of various components such as bacterial lipopolysaccharide, peptidoglycan and β‐1, 3‐glucans, and is known as stimulating nonspecific immune activity of shrimp. Bioflocs, therefore, are assumed to enhance shrimp immunity because they consume the bioflocs as additional food source. Although there are benefits for having an in situ microbial community in BFT systems, better understanding on these microorganisms, in particular molecular level, is needed. A fourteen‐day culture trial was conducted with postlarvae of Litopenaeus vannamei in the presence and absence of bioflocs. To determine mRNA expression levels of shrimp, we selected six genes (prophenoloxidase1, prophenoloxidase2, prophenoloxidase activation enzyme, serine proteinase1, masquerade‐like proteinase, and ras‐related nuclear protein) which are involved in a series of responses known as the prophenoloxidase (proPO) cascade, one of the major innate immune responses in crustaceans. Significant differences in shrimp survival and final body weights were found between the clear water and in the biofloc treatments. mRNA expression levels were significantly higher in the biofloc treatment than the clear water control. These results suggest that the presence of bioflocs in the culture medium gives positive effect on growth and immune‐related genes expression in L.vannamei postlarvae.  相似文献   

16.
This study aimed to evaluate the effects of dietary supplementation with sodium butyrate or polyhydroxybutyrate (PHB) on growth performance, as well as changes in intestinal microbiota and hemato‐immunological parameters, of Litopenaeus vannamei reared under a superintensive biofloc system. Twelve 800‐L tanks were each stocked with 250 shrimp/m3 (3.96 ± 0.04 g mean initial weight) and reared over a 6‐wk period. The basal diet and two test diets supplemented with 2% of each feed additive. At the conclusion of the growth trial shrimp fed with the butyrate‐supplemented diet, as compared with the control shrimp, showed higher survival and productivity and lower total bacterial and Thiosulfate‐citrate‐bile salts‐sucrose Agar (TCBS) counts in the intestine. However, no differences were observed in other performance parameters analyzed. Shrimp fed with both supplementation regimens also showed an increase in total and granular hemocytes, as well as an increase in serum agglutination titer. Shrimp offered diets supplemented with sodium butyrate had higher counts of hyaline cells. Thus, for L. vannamei reared in a superintensive biofloc system, it can be concluded that dietary supplementation of sodium butyrate, more so than PHB, acted as an immune system modulator by reducing the concentration of pathogenic bacteria in shrimp gut, thereby increasing survival and productivity.  相似文献   

17.
The biofloc technology (BFT) has recently gained attention as an economic and environmentally sustainable system for aquaculture. The use of BFT with salinized water could be used to minimize the negative effects of nitrogenous waste and improve the growth performance of Nile tilapia. This work evaluated the growth performance, survival, gill lesions, and fillet composition of tilapia fingerlings (Oreochromis niloticus) reared during 70 days with different salinities (0, 4, 8, 12, and 16 g/L) in a biofloc previously developed. The results indicated that the use of mature bioflocs alone was sufficient to avoid fingerling mortality due to nitrite peaks. Moreover, the salinized water, especially between 4 and 8 g/L (maximum points around 6 g/L), can be recommended in BFT to improve the growth performance of tilapia in the initial culture phase. The salinity level that was evaluated did not affect fillet composition nor the occurrence of gill lesions. The total ammonia nitrogen concentration was lower in freshwater than in salinized water (p < 0.05). Nitrite peaks in salinities of 12 and 16 g/L appeared later and were higher in comparison to other treatments. Considering minimal water exchange in BFT, the use of salinized water in this system may be environmentally viable.  相似文献   

18.
This study evaluated the potential for the replacement of fishmeal (FM) by biofloc meal (BM) in the diet of Litopenaeus vannamei postlarvae. Four isonitrogenous (437.42 g kg?1) and isocaloric (19.84 kJ g?1) diets were formulated, in which FM was replaced with BM at 0% (T0), 7.5% (T7.5), 15% (T15) and 30% (T30). A commercial diet (CD) was used as reference. The study was conducted over 42 days in 50 L tanks connected to a water recirculation system. All tanks were stocked with three postlarvae (initial weight 0.0023 g) per litre. Shrimp survival, weight gain (WG), final weight (FW), specific growth rate (SGR) and protein efficiency ratio (PER) were measured. Survival rates were high (>91.1%) in all treatments. As the T30 treatment returned a significantly (<0.05) better performance in WG, FW, SGR and PER than all other treatments, partial replacement of FM with BM does not appear to affect productivity. In fact, a regression analysis indicated that a FM to BM replacement level of over 20% may actually improve shrimp growth. In addition to providing a cost‐effective alternative ingredient for L. vannamei postlarvae diets, the production of meal also represents a more sustainable way of disposing of the excess of biofloc produced by BFT systems.  相似文献   

19.
The present study assessed the effects of different types of feeds and salinity levels on water quality, growth performance, survival rate and body composition of the Pacific white shrimp, Litopenaeus vannamei, juveniles in a biofloc system. Shrimp juveniles (2.56 ± 0.33 g) were cultured for 35 days in 300 L fibreglass tanks (water volume of 180 L) with a density of 1 g/L in six treatments. Three sources of feed (100% formulated feed, mixture of 66.6% formulated diet and 33.3% wet biofloc, and 100% wet biofloc) and two levels of salinity (10 and 32 ppt) were considered in two control groups and four biofloc treatments. Water quality parameters in the biofloc treatments were significantly better than control groups (p < .05). The highest increase in growth performance and survival rate were obtained in salinity of 32 ppt and mixed feed sources. Analysing the proximate composition of body shrimp indicates an increase in lipid and ash levels in biofloc treatments, which was more evident in the salinity of 32 ppt. In addition, the proximate analysis of shrimp body showed significant differences between biofloc treatments and control groups (p < .05). The highest FCR was found in the treatment with salinity level of 10 ppt and fed only with floc. Overall, it was found that the artificial diet supplemented with biofloc at the salinity of 32 showed better performance in the juvenile stage of Pacific white shrimp.  相似文献   

20.
We evaluated the performance of whiteleg shrimp Penaeus vannamei (Boone, 1931) in response to different stocking densities and acclimation periods. Shrimp postlarvae were acclimated from seawater (30 g L?1) to low‐salinity well water (<1.0 g L?1) at a constant hourly reduction rate of 40, 60, 80 and 100 h. After acclimation to low‐salinity well water, postlarvae from each acclimation time treatment were stocked in three replicate tanks at densities of 50, 100, 150 or 200 shrimps m?2 for 12 weeks of growth. Salinity averaged <1.0 g L?1 for each growth study. The different treatments resulted in significant differences in both the final body weight and the survival rate (SR). Shrimp acclimated for 100 h showed substantially improved survival (83%) relative to shrimp acclimated for shorter periods. Shrimp yields for all cultured periods ranged from 0.32 kg m?2 in tanks stocked at 50 m?2 to 1.14 kg m?2 in tanks stocked at 200 m?2. We conclude that whiteleg shrimp can be successfully grown in low‐salinity well water, and that the growth, production output and SRs are significantly higher when shrimp are acclimated for longer periods.  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号