Recirculating System (recirculating + system)

Distribution by Scientific Domains

Kinds of Recirculating System

  • adsorbent recirculating system
  • molecular adsorbent recirculating system


  • Selected Abstracts


    Acute renal failure in patients with cirrhosis: Perspectives in the age of MELD

    HEPATOLOGY, Issue 2 2003
    Richard Moreau
    In patients with cirrhosis, acute renal failure is mainly due to prerenal failure (caused by renal hypoperfusion) and tubular necrosis. The main causes of prerenal failure are "true hypovolemia" (induced by hemorrhage or gastrointestinal or renal fluid losses), sepsis, or type 1 hepatorenal syndrome (HRS). The frequency of prerenal failure due to the administration of nonsteroidal anti-inflammatory drugs or intravascular radiocontrast agents is unknown. Prerenal failure is rapidly reversible after restoration of renal blood flow. Treatment is directed to the cause of hypoperfusion, and fluid replacement is used to treat most cases of "non-HRS" prerenal failure. In patients with type 1 HRS with very low short-term survival rate, liver transplantation is the ideal treatment. Systemic vasoconstrictor therapy (with terlipressin, noradrenaline, or midodrine [combined with octreotide]) may improve renal function in patients with type 1 HRS waiting for liver transplantation. MARS (for molecular adsorbent recirculating system) and the transjugular intrahepatic portosystemic shunt may also improve renal function in these patients. In patients with cirrhosis, acute tubular necrosis is mainly due to an ischemic insult to the renal tubules. The most common condition leading to ischemic acute tubular necrosis is severe and sustained prerenal failure. Little is known about the natural course and treatment (i.e., renal replacement therapy) of cirrhosis-associated acute tubular necrosis. [source]


    A guide to the embryonic development of the shovelnose sturgeon (Scaphirhynchus platorynchus), reared at a constant temperature

    JOURNAL OF APPLIED ICHTHYOLOGY, Issue 4 2007
    R. E. Colombo
    Summary Described is the sequence and timing of embryologic development of shovelnose sturgeon, (Scaphirhynchus platorynchus) reared at a constant temperature 20 ± 0.5°C. Artificially spawned, fertilized eggs were held in a recirculating system. Embryos were sampled hourly during the first 48 h of development and every 3 h thereafter. Embryos were viewed and imaged at 35× magnification. The first cleavage furrow appeared 2 h post-fertilization; early (synchronous) cleavage was completed after 7 h. Blastulation concluded at 16 h when the dorsal blastopore lip formed. The slitlike blastopore appeared at 29 h, signifying the completion of gastrulation. At 33 h, the rudiments of the excretory system emerged, followed by closing of the neural tube at 36 h and formation of the s-shaped heart at 60 h. The body continued to elongate with mass hatch occurring at 102 h. After hatch, larvae swam into the water column and drifted in the flow for approximately 2 days after which the larvae became positively rheotaxic. After expulsion of the pigment plug, the larvae began exogenous feeding and other structures continued to develop. Metamorphosis was completed after 26 days of development. Because the shovelnose sturgeon possesses developmental patterns similar to those of other sturgeon, we can use this species as a model for the closely related pallid and Alabama sturgeon. [source]


    Effects of the Prebiotics GroBiotic® -A and Inulin on the Intestinal Microbiota of Red Drum, Sciaenops ocellatus

    JOURNAL OF THE WORLD AQUACULTURE SOCIETY, Issue 4 2009
    Gary Burr
    Two separate feeding trials examined the effects of dietary supplementation of the prebiotics GroBiotic® -A and inulin on growth performance and gastrointestinal tract microbiota of the red drum, Sciaenops ocellatus. In the first feeding trial, fish meal-based diets without prebiotics or supplemented with either GroBiotic® -A or inulin at 1% of dry weight were fed to triplicate groups of juvenile red drum (initial weight of 2.6 g) in 110-L aquaria operated as a brackish water (7 ppt) recirculating system for 8 wk. In the second feeding trial, soybean meal/fish meal-based diets supplemented with either GroBiotic® -A or inulin at 1% of dry weight were fed to triplicate groups of red drum (initial weight of 15.8 g) in 110-L aquaria operated as either a common recirculating water system or closed system with individual biofilters (independent aquaria) for 6 wk. Supplementation of the prebiotics in either feeding trial did not alter weight gain, feed efficiency ratio, or protein efficiency ratio of red drum fed the various diets. In the second feeding trial, the culture system significantly affected weight gain, feed efficiency ratio, and protein efficiency ratio although there were no effects of dietary treatments on fish performance or whole-body protein, lipid, moisture, or ash. Denaturing gradient gel electrophoresis (DGGE) analysis of the gastrointestinal tract microbial community showed no effect of the dietary prebiotics as the microbial community appeared to be dominated by a single organism with very low diversity when compared with other livestock and fish species. DGGE of the microbial community in the biofilters of the independent aquariums showed a diverse microbial community that was not affected by the dietary prebiotics. [source]


    Acute systemic, splanchnic and renal haemodynamic changes induced by molecular adsorbent recirculating system (MARS) treatment in patients with end-stage cirrhosis

    ALIMENTARY PHARMACOLOGY & THERAPEUTICS, Issue 5 2007
    G. DONATI
    Summary Aim To evaluate the acute effect of treatment with the molecular adsorbent recirculating system (MARS) on splanchnic, renal and systemic haemodynamics in patients with end-stage cirrhosis. Methods Twelve patients with end-stage cirrhosis, undergoing MARS treatment, were enrolled. The following haemodynamic parameters were measured by means of Doppler ultrasonography and thoracic electrical bioimpedance, before and after each session: portal velocity, renal and splenic resistance indices, cardiac output, cardiac stroke volume, heart rate, mean arterial pressure, systemic vascular resistance. Results Median portal velocity increased significantly after treatment (23.7 vs. 20.3 cm/s, P < 0.05) while renal resistance index (0.72 vs. 0.75, P < 0.05) and splenic resistance index (0.60 vs. 0.65, P < 0.05) decreased significantly. Mean arterial pressure (83 vs. 81 mmHg, P < 0.05) and vascular resistance (899 vs. 749 dyne. s/cm5, P < 0.05) increased significantly, while cardiac output and stroke volume showed no significant changes. Conclusions Data emerging from this investigation suggest that MARS treatment improves significantly various haemodynamic alterations in cirrhotic patients in the short term. The observed decrease in renal vascular resistance and improvement in splenic resistance index, a parameter related to portal resistance, which leads us to hypothesize that these haemodynamic effects are probably mediated by clearance of vasoactive substances during MARS treatment. [source]


    Nutrients apparent digestibility coefficients of selected protein sources for juvenile Siberian sturgeon (Acipenser baerii Brandt), compared by two chromic oxide analyses methods

    AQUACULTURE NUTRITION, Issue 6 2009
    H. LIU
    Abstract Apparent digestibility coefficients (ADCs) of dry matter (ADCd), crude protein (ADCp), energy (ADCe) and amino acids in selected feedstuffs were determined for juvenile Siberian sturgeon (8.38 ± 0.20 g). The tested feedstuffs were fishmeal (FM), meat and bone meal (MBM), poultry by-product meal, hydrolysed feather meal, fermented feather meal solvent-extracted cottonseed meal and soybean meal. ADCs were determined using a reference diet and test diets at 7 : 3 ratios with 5 g kg,1 chromic oxide (Cr2O3) as an inert marker. Fish were reared in a recirculating system and fed to apparent satiation five times daily. Cr2O3 in diets and faeces samples were determined by inductively coupled plasma atomic emission spectrometry (ICP-AES) and acid-digestion colorimetry (AC) methods, respectively. The results showed that ICP-AES method was more accurate for Cr2O3 determination than AC method, and the results determined by ICP-AES method were used in this study. ADCd and ADCp of seven tested ingredients were lowest for MBM (59.1 and 84.5%) and highest for FM (79.9 and 94.5%); ADCe of tested ingredients were from 71.8% for SECM to 93.2% for FM. ADCs of amino acid in test ingredients followed similar trend to the ADCp. The ADCs of individual amino acids varied from 61.6% (histidine in MBM) to 98.8% (valine in FM). [source]


    Lecithin requirements of juvenile Australian red claw crayfish Cherax quadricarinatus

    AQUACULTURE NUTRITION, Issue 4 2003
    K.R. Thompson
    Abstract Australian red claw crayfish Cherax quadricarinatus is considered a popular crustacean species in several countries around the world because of its large size potential and resemblance to high-priced American lobsters. However, little is currently known of the nutrient requirements and practical diet formulations for red claw. Lecithin has been shown to be required in the diets of several crustacean species, but there are no reports of dietary lecithin requirements for red claw. A 10-week feeding trial was conducted in an effort to evaluate lecithin requirements for juvenile red claw. Juvenile red claw (mean individual weight of 1.6 ± 0.91 g) were individually stocked in a recirculating system at random into 80 plastic-mesh culture units, each containing its own individual water line. There were 20 red claw per treatment (diet). Water was recirculated through biological and mechanical filters. Four semi-purified diets were formulated to contain increasing percentages of commercial soya bean lecithin (0, 0.5, 1.0 and 2.0%). Diet ingredients included solvent-extracted menhaden fish meal (FM), casein, dextrin, wheat flour, pellet binder, vitamin and mineral mix, cod liver oil, and corn oil. Semi-purified diets were formulated to contain 40% protein using casein, menhaden FM, and wheat flour as protein sources. After 10 weeks, no significant differences (P > 0.05) were found in final weight, percentage weight gain and specific growth rate with average values of 13.0 g, 934%, and 3.14% day,1, respectively. Percentage survival was high during the 10-week period (100, 95, 100 and 95%) as only two individuals died during the study; one of these, because of an escape from the culture unit. There was also no significant differences (P > 0.05) in percentage moisture, protein, fat and ash in whole-body red claw carcasses (wet-weight basis) among any treatment (diet) and averaged 77.1, 12.6, 1.3 and 6.2%, respectively. Based upon the present study, these results indicate that a diet containing 5% cod liver oil and 1% corn oil, and having no supplemental lecithin, may be sufficient for growth and survival of juvenile red claw crayfish. [source]


    Artificial incubation of noble crayfish (Astacus astacus) eggs in a partially recirculating system using formaldehyde as an antifungal treatment

    AQUACULTURE RESEARCH, Issue 10 2010
    Antonín Kouba
    Abstract There is little information on the long-term artificial incubation of noble crayfish eggs. The present study evaluated artificial incubation in a partially recirculating system using formaldehyde baths as antifungal prophylaxis. Crayfish eggs were treated three times a week in a formaldehyde bath of 3000 ppm for 15 and 20 min and in 2500 ppm for 15, 20 and 25 min. In all treated groups, high final survival rates (87.8,92.0%) to stage 2 juveniles were obtained after 83 days. Significantly lower survival was observed in the control group (45.4%). It was concluded that recirculating systems can be used successfully for artificial incubation of crayfish eggs in order to conserve water. Formalin was found as an effective fungicide but its use should be carefully considered because of its safety issues for farm staff and environmental pollution. [source]


    Size-related oxygen consumption and ammonia excretion of Eurasian perch (Perca fluviatilis L.) reared in a recirculating system

    AQUACULTURE RESEARCH, Issue 1 2009
    Vlastimil Stejskal
    Abstract Oxygen consumption (OC) and ammonia excretion rates (AE) of perch were measured under commercial-like conditions (temperature 23.3 °C) in both fed (F) and feed-deprived groups (D). Measurements were taken in triplicate in six sized batches of perch ranging from 44.8 to 336.2 g. The mean daily OC was 288.3,180.6 mg O2 kg,1 h,1 for group F fish ranging in size from 44.8 to 279.4 g body weight. The mean daily AE expressed as total ammonia nitrogen (TAN) was 13.8,5.2 mg TAN kg,1 h,1 in the same groups. Daily peaks of OC in group F perch were observed 6 h after the onset of feeding for each size group with relatively stable values up to the end of feeding. Peaks of daily AE in group F perch were observed 10 h after the onset of feeding in each size group, with a rapid decrease up to 16 h after onset. In group D, OC was 181.1,110.5 mg O2 kg,1 h,1 in the weight range 57.9,336.2 g. The daily mean AE was 1.7,0.5 TAN kg,1 h,1 in this group. No dramatic peaks of OC and AE were observed in group D perch. [source]


    Effects of dietary protein and lipid levels on growth performance and body composition of black sea bass Centropristis striata (Linnaeus 1758) during grow-out in a pilot-scale marine recirculating system

    AQUACULTURE RESEARCH, Issue 4 2009
    Md Shah Alam
    Abstract The influence of four formulated practical diets, with different protein and lipid levels, on the growth and body composition of black sea bass (Centropristis striata L.) pre-adults was evaluated in a pilot-scale marine recirculating system. Four test diets were prepared with a combination of two protein levels (44% and 54%) and two lipid levels (10% and 15%). The diets were as follows: low protein and low lipid (LP:LL; 44:10), low protein and high lipid (LP:HL; 44:15), high protein and low lipid (HP:LL; 54:10) and high protein and high lipid (HP:HL; 54:15). Fish (mean weight=75.5 g) were fed the respective diets for 90 days. For fish fed LP:HL, body weight gain was significantly (P<0.05) higher than fish fed LP:LL. Increasing the protein level from 44% to 54% did not produce a significant effect on weight gain at high lipid level. A significant (P<0.01) interactive effect between dietary protein and lipid levels on the growth and feed utilization was observed. Total lipid content in the whole body, muscle and liver was significantly affected by the dietary lipid levels. The results suggested that a combination of 44% dietary protein and 15% lipid was optimal for the growth of black sea bass. [source]


    Improved techniques for rearing mud crab Scylla paramamosain (Estampador 1949) larvae

    AQUACULTURE RESEARCH, Issue 14 2007
    Truong Trong Nghia
    Abstract A series of rearing trials in small 1 L cones and large tanks of 30,100 L were carried out to develop optimal rearing techniques for mud crab (Scylla paramamosain) larvae. Using water exchange (discontinuous partial water renewal or continuous treatment through biofiltration) and micro-algae (Chlorella or Chaetoceros) supplementation (daily supplementation at 0.1,0.2 million cells mL,1 or maintenance at 1,2 millions cells mL,1), six different types of rearing systems were tried. The combination of a green-water batch system for early stages and a recirculating system with micro-algae supplementation for later stages resulted in the best overall performance of the crab larvae. No clear effects of crab stocking density (50,200 larvae L,1) and rotifer (30,60 rotifers mL,1) and Artemia density (10,20 L,1) were observed. A stocking density of 100,150 zoea 1 (Z1) L,1, combined with rotifer of 30,45 mL,1 for early stages and Artemia feeding at 10,15 nauplii mL,1 for Z3,Z5 seemed to produce the best performance of S. paramamosain larvae. Optimal rations for crab larvae should, however, be adjusted depending on the species, larval stage, larval status, prey size, rearing system and techniques. A practical feeding schedule could be to increase live food density from 30 to 45 rotifers mL,1 from Z1 to Z2 and increase the number of Artemia nauplii mL,1 from 10 to 15 from Z3 to Z5. Bacterial disease remains one of the key factors underlying the high mortality in the zoea stages. Further research to develop safe prophylactic treatments is therefore warranted. Combined with proper live food enrichment techniques, application of these findings has sustained a survival rate from Z1 to crab 1,2 stages in large rearing tanks of 10,15% (maximum 30%). [source]


    Growth and production of hatchery-reared juvenile spotted babylon Babylonia areolata Link 1807 cultured to marketable size in intensive flowthrough and semi-closed recirculating water systems

    AQUACULTURE RESEARCH, Issue 5 2000
    N Chaitanawisuti
    Hatchery-reared juvenile spotted babylon Babylonia areolata (mean initial shell length 12.8 mm) were cultured intensively to marketable size in three 3.0 × 2.5 × 0.7 m indoor canvas rectangular tanks. The duplicate treatments of flowthrough and semi-closed recirculating sea-water systems were compared at an initial stocking density of 300 individuals m,2 (2250 juveniles per tank). The animals were fed ad libitum with fresh carangid fish Selaroides leptolepis once daily. During 240 culture days, average growth rates in shell length and body weight were 3.86 mm month,1 and 1.47 g month,1 for the flowthrough system and 3.21 mm month,1 and 1.10 g month,1 for those in the semi-closed recirculating system. Survival in the flowthrough system (95.77%) was significantly higher than that in the semi-closed recirculating system (79.28%). Feed conversion ratios were 1.68 and 1.96 for flowthrough and semi-closed recirculating systems respectively. [source]


    Thermodynamic Considerations in Solid Adsorption of Bound Solutes for Patient Support in Liver Failure

    ARTIFICIAL ORGANS, Issue 7 2008
    John F. Patzer II
    Abstract:, New detoxification modes of treatment for liver failure that use solid adsorbents to remove toxins bound to albumin in the patient bloodstream are entering clinical evaluations, frequently in head-to-head competition. While generally effective in reducing toxin concentration beyond that obtainable by conventional dialysis procedures, the solid adsorbent processes are largely the result of heuristic development. Understanding the principles and limitations inherent in competitive toxin binding, albumin versus solid adsorbent, will enhance the design process and, possibly, improve detoxification performance. An equilibrium thermodynamic analysis is presented for both the molecular adsorbent recirculating system (MARS) and fractionated plasma separation, adsorption, and dialysis system (Prometheus), two advanced systems with distinctly different operating modes but with similar equilibrium limitations. The Prometheus analysis also applies to two newer approaches: sorbent suspension reactor and microsphere-based detoxification system. Primary results from the thermodynamic analysis are that: (i) the solute,albumin binding constant is of minor importance to equilibrium once it exceeds about 105 L/mol; (ii) the Prometheus approach requires larger solid adsorbent columns than calculated by adsorbent solute capacity alone; and (iii) the albumin-containing recycle stream in the MARS approach is a major reservoir of removed toxin. A survey of published results indicates that MARS is operating under mass transfer control dictated by solute,albumin equilibrium in the recycle stream, and Prometheus is approaching equilibrium limits under current clinical protocols. [source]


    Disposition of isosteviol in the rat isolated perfused liver

    CLINICAL AND EXPERIMENTAL PHARMACOLOGY AND PHYSIOLOGY, Issue 5-6 2010
    Hongping Jin
    Summary 1. The aim of the present study was to investigate the mechanisms involved in the clearance of isosteviol using the rat isolated perfused liver. 2. Six livers from male Sprague-Dawley rats were perfused with 15.7 ,mol isosteviol in a recirculating system. Perfusate and bile samples were collected for 60 min and the liver was collected at the end of the perfusion. All samples collected were incubated with ,-glucuronidase. Isosteviol,glucuronide was determined as equivalent isosteviol. Isosteviol concentrations were determined using a previously developed liquid chromatography,tandem mass spectrometry method. The final isosteviol liver/perfusate (L/P), bile/liver (B/L) and isosteviol-glucuronide in bile/liver (BG/LG) ratios were determined. 3. Isosteviol has a high clearance (21.4 ± 4.8 mL/min) from the perfusate, with a short half-life (13 ± 4 min). ,-Glucuronidase incubation revealed that isosteviol is conjugated in the liver and excreted into the bile. There was no isosteviol-glucuronide detected in perfusate samples. The total recovery of the rat isolated perfused liver system is 74 ± 14% and glucuronidated isosteviol accounted for 23 ± 4% of the administered dose. 4. In conclusion, we are the first to characterize the metabolism of isosteviol using rat isolated liver perfusion. Our results strongly suggest that the liver is the main organ of isosteviol elimination and that isosteviol is glucuronidated in the liver before it is excreted into the bile. [source]


    Indocyanine green elimination but not bilirubin indicates improvement of graft function during MARS therapy

    CLINICAL TRANSPLANTATION, Issue 6 2007
    Stefan Scheingraber
    Abstract:, Measurement of indocyanine green plasma disappearance rate (PDRICG) has been suggested as a meaningful liver function parameter. However, there are only very limited data concerning its value in the monitoring of graft dysfunction (GDF) and primary non-function (PNF) especially during molecular absorbent recirculating system (MARS) therapy. This study was therefore performed to evaluate the diagnostic accuracy to detect and monitor GDF with the measurement of the PDRICG in direct comparison with conventional markers like bilirubin and prothrombin time (PT). Of the 19 liver recipients, four patients with GDF and two patients with PNF were treated with 38 MARS cycles. Only PDRICG did reliably indicate liver function between patients with GDF/PNF and patients with sufficient graft function who served as controls. Moreover, receiver operating characteristic analysis showed the highest areas under the curve (AUC) for PDRICG (AUCPDRICG max: 0.840, AUCPDRICG max: 0.822), followed by bilirubin (AUCbilirubin: 0.528) and PT (AUCPT: 0.546). In contrast to the decrease of the serum bilirubin concentration due to MARS, a noticeable improvement of PDRICG was evident only in patients with GDF. Patients with acute fulminant failure and PNF had significantly lower PDRICG values, which did not improve even during continuous MARS treatments. Conclusively, monitoring of PDRICG is superior to bilirubin and PT measurements to determine the graft function especially in patients with PNF and GDF undergoing MARS therapy. [source]


    Artificial incubation of noble crayfish (Astacus astacus) eggs in a partially recirculating system using formaldehyde as an antifungal treatment

    AQUACULTURE RESEARCH, Issue 10 2010
    Antonín Kouba
    Abstract There is little information on the long-term artificial incubation of noble crayfish eggs. The present study evaluated artificial incubation in a partially recirculating system using formaldehyde baths as antifungal prophylaxis. Crayfish eggs were treated three times a week in a formaldehyde bath of 3000 ppm for 15 and 20 min and in 2500 ppm for 15, 20 and 25 min. In all treated groups, high final survival rates (87.8,92.0%) to stage 2 juveniles were obtained after 83 days. Significantly lower survival was observed in the control group (45.4%). It was concluded that recirculating systems can be used successfully for artificial incubation of crayfish eggs in order to conserve water. Formalin was found as an effective fungicide but its use should be carefully considered because of its safety issues for farm staff and environmental pollution. [source]


    Effects of stocking density on the nutrient budget and growth of the western king prawn (Penaeus latisulcatus Kishinouye) in a recirculating aquaculture system

    AQUACULTURE RESEARCH, Issue 10 2010
    Le Van Khoi
    Abstract Intensification in the commercial culture of prawns can have a significant impact on the water quality and hence on the survival, growth and the surrounding environment. The present study aims to evaluate the effects of stocking density on the water quality and performance of the western king prawns (Penaeus latisulcatus) and the nutrient budget of the culture environment. Four stocking densities of 4, 8, 16 and 32 prawns m,2 were tested in 12 recirculating systems. Prawn weight and specific growth rate increased with decreasing stocking density, while the survival rate showed the reverse trend. The mean total ammonia nitrogen, nitrate nitrogen, total phosphorus and soluble reactive phosphorus were significantly higher (P<0.05) at the higher stocking density. The nutrient budget revealed that the prawns could assimilate only 9.34,20.13% nitrogen and 4.97,11.25% phosphorus of the total nutrient inputs. The drained water at harvest was the major sink of phosphorus and nitrogen at stocking densities of 4, 8 and 16, which accounted for 45.59,64.82% and 44.28,65.62% of the total inputs, respectively, while a significant proportion of nitrogen sunk into the sediment at 32 prawns m,2. The study suggested that the stocking densities of western king prawns can be up to 16 prawns m,2 in the recirculating water environment. [source]


    Protein requirements of Nile tilapia (Oreochromis niloticus) fry cultured at different salinities

    AQUACULTURE RESEARCH, Issue 8 2010
    Edvino Larumbe-Morán
    Abstract Effect of isolipidic (62.7 ± 5.0 g kg,1) diets with protein levels of 204.6 (T20), 302.3 (T30), 424.6 (T40) or 511.0 g kg,1 (T50) on growth and survival in Nile tilapia (Oreochromis niloticus Linnaeus 1758) fry cultured for 70 days at one of four salinities (0, 15, 20 and 25 g L,1) was evaluated. A bifactorial (4 × 4) design was used with 16 treatments run in triplicate and 20 fry (0.25 ± 0.04 g) per replicate under semi-controlled conditions. Four independent, recirculating systems (one per salinity level) were used, each one with 12 circular tanks (70 L capacity), filters and constant aeration. The different salinities had no significant effect on growth. Weight gain improved significantly as dietary protein content increased, although organisms fed the T50 diet had a lower growth rate. Survival was highest (98.33%) in the T50/15 (protein/salinity levels) treatment and lowest (71.0%) in the T20/20 treatment, with no pattern caused by the variables. The T40/25, T40/20 and T50/0 treatments produced the most efficient growth and feed utilization values while the T20 treatments at all the salinities resulted with the lowest performance. With the exception of the T50 treatments, a non-significant tendency to increased weight gain was observed as water salinity increased, suggesting that the salinity of the culture environment does not influence dietary protein requirements in Nile tilapia O. niloticus fry. [source]


    Effects of photoperiod on growth and spawning efficiency of Nile tilapia (Oreochromis niloticus L.) broodstock in a recycling system

    AQUACULTURE RESEARCH, Issue 12 2007
    Abdel-Fattah M El-Sayed
    Abstract This study was conducted to evaluate the effects of photoperiod on the growth, feed conversion ratio (FCR) and spawning performance of Nile tilapia (Oreochromis niloticus) broodstock. Duplicate groups of two males (66±3.04 g) and six females (50.5±1.58 g) were stocked in 0.4 m3 fibreglass tanks in a recirculating water system at a male:female ratio of 1:3. The fish were subjected to four photoperiod treatments: 24:0 light:dark (L:D), 18L:6D, 12L:12D and 6L:18D. Light intensity was kept constant at about 2500 lx throughout the study. The fish were fed a commercial tilapia diet (35% crude protein and 16.6 MJ GE kg,1) at a daily rate of 2,3% of tank biomass, twice a day, for 130 days. Males grew significantly faster than females under all photoperiod regimes. The best growth rate and FCR were attained at 18L:6D, followed by 24L:0D, 12L:12D and 6L:18D respectively. The number of eggs per female, number of eggs per spawn and number of spawnings per female were all significantly higher in the 12L:12D treatment than in all other photoperiod cycles. Interspawning intervals and days elapsed per spawn were also shorter in the 12L:12D treatment. The time to first spawning was slightly longer in the 24L:0D and 6L:18D than in 12L:12D and 18L:6D light phases. The 18L:6D and 6L:18D photoperiods produced the lowest spawning performance. It is concluded that a 12L:12D photoperiod regime should be adopted for maximum fecundity, seed production and spawning frequencies of Nile tilapia broodstock reared in intensive, recirculating systems. If maximum reproduction is desired, a near-natural day length photoperiod should be used. [source]


    Effect of salinity on carrying capacity of adult Nile tilapia Oreochromis niloticus L. in recirculating systems

    AQUACULTURE RESEARCH, Issue 16 2006
    M A Kabir Chowdhury
    Abstract Effect of salinity on carrying capacity of a recirculation system for Nile tilapia, Oreochromis niloticus L.; production was assessed. Survival, growth and feed conversion ratio of adult Nile tilapia fed 30% crude protein diet for 88 days were measured at three different salinity levels (8, 15 and 25 g L,1) and two stocking densities (20 and 40 m,3) in three independent recirculating systems. Highest survival (98%) and a linear growth in net biomass (P<0.01) was observed in both densities at 8 g L,1 and in 20 m,3 treatment at 15 g L,1. Highest net biomass growth was observed in the 40 m,3 stocking density treatment at 8 g L,1 salinity level (P<0.05). Overall biomass growth was significantly affected by salinity indicating a decrease in Nile tilapia carrying capacity with increased salinity. About 11 000 kg ha,1 crop,1 of Nile tilapia can be obtained in recirculating systems at 8 g L,1 salinity, significantly higher than the net production at 15 g L,1 (5200 kg ha,1 crop,1) and 22 g L,1 (4425 kg ha,1 crop,1). [source]


    Growth and production of hatchery-reared juvenile spotted babylon Babylonia areolata Link 1807 cultured to marketable size in intensive flowthrough and semi-closed recirculating water systems

    AQUACULTURE RESEARCH, Issue 5 2000
    N Chaitanawisuti
    Hatchery-reared juvenile spotted babylon Babylonia areolata (mean initial shell length 12.8 mm) were cultured intensively to marketable size in three 3.0 × 2.5 × 0.7 m indoor canvas rectangular tanks. The duplicate treatments of flowthrough and semi-closed recirculating sea-water systems were compared at an initial stocking density of 300 individuals m,2 (2250 juveniles per tank). The animals were fed ad libitum with fresh carangid fish Selaroides leptolepis once daily. During 240 culture days, average growth rates in shell length and body weight were 3.86 mm month,1 and 1.47 g month,1 for the flowthrough system and 3.21 mm month,1 and 1.10 g month,1 for those in the semi-closed recirculating system. Survival in the flowthrough system (95.77%) was significantly higher than that in the semi-closed recirculating system (79.28%). Feed conversion ratios were 1.68 and 1.96 for flowthrough and semi-closed recirculating systems respectively. [source]