Polyethylene Tanks Research Articles

Probiotic supplementation affects IGF-1 and leptin levels in Nile tilapia hepatopancreatic tissue

ABSTRACT This work aimed to assess the effect of the probiotic strain, Lactobacillus plantarum, on the levels of leptin, IGF-1 and their receptors on the hepatopancreatic tissues of Nile tilapia (Oreochromis niloticus) and then correlate fish growth performance and gut microbiological parameters. Fish juveniles (±23g) were reared in a recirculation system with constant aeration and temperature (25°C). They were distributed into six polyethylene tanks (45L) and fed twice a day at 5% of the tank biomass with the respective diets: control (commercial diet without probiotic) and supplemented with L. plantarum inoculum (1 x 108 CFU mL-1), both in triplicate. After 30 days of feeding, L. plantarum-fed fishes showed greater weekly growth rate, final weight, and feed conversion rate, in addition to higher count of lactic-acid bacteria and lower count of pathogenic bacteria in the intestinal tract, when compared to the control group. The immunostaining intensity for IGF-1 and leptin hormones was lower after L. plantarum supplementation than in the control group, with no change in the level for receptors. This reduction could implicate important changes in fish metabolism and homeostasis.

Effects of stocking density during live transportation on haematological parameters of Siberian sturgeon ( Acipenser baerii , Brandt, 1869)

In this study, we investigated the effects of different stocking densities water quality and blood parameters during the transportation of the Siberian sturgeon (Acipenser baerii). Experiments were carried out in high-density polyethylene tank with three different stocking densities (50, 100 and 150 kg/m3) for 20 h. Ammonium nitrogen (NH4-N) and nitrite nitrogen (NO2-N) were measured in the water samples. The erythrocyte, leucocyte, haematocrit (HCT), haemoglobin (Hb), cortisol, and sodium ion (Na+) were measured in blood samples. Ammonium nitrogen and nitrite nitrogen concentrations in the water have increased in parallel with the stocking density depending on the time. In the highest stocking density, the maximum levels of NH4-N and NO2-N at the 16th h reached 2.64 mg/L and 4.74 mg/L, respectively. Erythrocyte, leucocyte, HCT, and Hb values did not differ significantly between the experimental groups (p > .05). The results showed that fish could be transported safely for 20 h in 15℃ water temperature at 50 kg/m3 stocking density; however, stocking density of 100 kg/m3 and over could threaten fish welfare and health as from 16th h.

Susceptibility of Malaysian Rice (Oryza sativa L.) Cultivar to Saline Water Submergence Based on the Morphological Traits

Saline water submergence is a newly emerge abiotic stress jeopardizing rice production especially for the rice fields located nearby or alongside coastal areas. The stress was caused by the intrusion of sea water into those rice fields causing flash flood mainly during monsoon season. The present study was conducted to evaluate susceptibility level of selected Malaysian rice cultivars to saline water submergence at seedling stage based on the morphological traits and survival rate. There were six genotypes involved in the study mainly IR64-Sub1 as submergence tolerant control, Pokkali as salinity tolerant control, IR64 as susceptible control and MR297, MR284 and MR253 as local rice cultivars, respectively. The experiment was conducted using split plot design with three replications. On the day 14 after germination, all rice seedlings were totally submerged of about one-meter depth in a polyethylene tank containing saline water at 0, 4, 8 and 12 dS/m for 14 days while the non-submerged plant was control of the experiment. Seedling growth attributes and survival rate were recorded before, right after de-submerged and 14 days after de-submerged. All genotypes however were susceptible to saline water submergence at 4, 8 and 12 dS/m. In contrast, under 0 dS/m, IR64-Sub1 recorded significantly higher survival rate at 83% as compared to MR284 (17%), MR297 (17%), Pokkali (8%), MR253 (0%) and IR64 (0%). All genotypes were not survived under saline submergence. Therefore, further phenotypic screening of rice genetic resources originated from or nearby coastal areas could be suggested in order to increase chance of identifying potentially tolerant genotype to saline water submergence.

Evaluation of the adequacy of a spring‐mass model in analyses of liquid sloshing in anchored storage tanks

AbstractThis research addresses the influence of the load characteristics, that is, frequency content and maximum acceleration, on the wall stresses of an anchored water storage tank. A low‐density polyethylene tank with a range of six different aspect ratios (water height to tank radius) was tested using a shake table. Eight sine excitations that cover the lowest free vibration frequency of the tank‐water system were applied. Additionally, two sets of five Ricker wavelet excitations were utilized. Each set represents potential earthquakes with a bandwidth between a low and a high dominant frequency. The experimentally determined maximum stresses and those obtained from calculations using a common spring‐mass model employed for seismic analysis of tanks were compared. The results reveal that the relationship between the excitation frequency and the wall stresses strongly depends on the sloshing behavior, especially when the frequency of loading is in the vicinity of the lowest free–vibration frequency of the tank–water system. When the frequencies are dissimilar, there is a proportional relationship between stress and the maximum acceleration of the excitation. The spring‐mass model was found to underestimate both the maximum hoop stress (for aspect ratios greater than two) and axial stress (for aspect ratios equal to 0.5). This occurs because is the spring‐mass model cannot capture, in all cases, the contribution of chaotic sloshing to wall stress.

Larval rearing and ontogeny of digestive enzyme activities in yellowfin seabream (Acanthopagrus latus, Houttuyn 1782)

The present research was conducted to provide insight into digestive larval capacity in Acanthopagrus latus larvae from hatching up to 30 days after hatching (DAH). Newly hatched larvae were stocked into six 300-L cylindrical polyethylene tanks at a density of larvae 50 larvae/L and reared by means of the green water system using Nannochloropsis oculata (0.5 × 106/mL). After mouth opening, larvae were fed with rotifers (5–16 individual/mL) from 2 to 20 DAH; then, Artemia nauplii (0.5–3.0 individuals/mL) were offered to larvae from 18 to 30 DAH, meanwhile a commercial microdiet was offered to larvae from 25 to 30 DAH. Larval performance in terms of growth and survival, and the assessment of the activity of selected digestive enzymes ontogeny of digestive enzymes activities was evaluated in larvae sampled at 0 (hatching), 7, 15, 22 and 30 DAH. Larvae showed an exponential growth characterized by two different growth stanzas, a first one characterized by slow growth rates comprised between hatching to 15 DAH (4.7 ± 0.2 mm), followed by a period of faster growth rates between 16 and 30 DAH (7.5 ± 0.6 mm). The activities of the brush border (alkaline phosphatase, ALP) and cytosolic (leucine-alanine peptidase, LAP) enzymes, as well as those of the pancreatic ones like total alkaline proteases, bile salt-activated lipase and α-amylase were detected from the mouth opening stage. Total activities of pancreatic and gastric enzymes increased with larval growth showing an enhancement of digestive capacities with larval age and size. The intestinal maturation in A. latus as assessed by the ratio of AP to LAP did not occur as expected by end of the first month of life suggesting the complete establishment of digestive luminal processes may take place at older ages. This study related to the growth patterns and ontogenic changes in activity of pancreatic, gastric and intestinal enzymes in A. latus and their nutritional regulation may be considered as the first step for improving the larviculture, as well as assessing and refining the nutritional requirements during the larval and early juvenile stages of this sparid species.

Dicamba residues in sprayers: Phytotoxicity on non-dicamba tolerant soybean

ABSTRACT This study aimed to evaluate the dicamba residue after cleanout procedures in sprayers with different tank materials (fiberglass and polyethylene) and its effects on the symptomology of non-dicamba tolerant (DT) soybean. The experiment consisted of spraying rinsates collected during a cleanout of boom sprayers on non-DT soybean at the V3 stage. Once the dicamba solution was mixed in the sprayer tank and sprayed, four rinses were made, and for each rinse, a sample was collected. The dicamba residue analyses in each rinse solution were conducted in a completely randomized design with three replicates in a 2 × 4 factorial scheme, corresponding to two sprayer tank materials (fiberglass and polyethylene) and four rinses, using High-Performance Liquid Chromatograph (HPLC). The evaluation of the potential risk of injury on non-DT soybean caused by dicamba residue was conducted in a randomized block design with four replicates and a 2 × 4 + 1 factorial scheme, corresponding to two types of sprayer tank material (fiberglass and polyethylene), four rinses, and control (without application). The dicamba was effectively removed using at least three rinses regardless of spray tank material. Fiberglass tank sprayer retained more residue in the first rinsate, but similar to polyethylene tank sprayer in the following rinses. Plant height was reduced by spraying rinsates collected from the first rinse regardless of tank material. In contrast, visual estimation of injury and reduced yield were observed due to the rinsate application collected from the first and second rinses.

Synergistic effects of mangrove leaf litter and supplemental feed on water quality, growth and survival of shrimp (Penaeus monodon, Fabricius, 1798) post larvae

Shrimp based mangrove-aquaculture (silvo-aquaculture) is practiced in many countries of the world and leaf litter of different mangrove tree species is a potential nutrient source in these systems. The present study evaluated the effects of mangrove leaf litter from four mangrove species (Sonneratia apetala, S. caseolaris, Avicennia officinalis and Heritiera fomes) on the production of juvenile shrimp (Penaeus monodon) with and without supplemental feed. Fifteen-day-old post larvae (PL15) with an average weight of 0.01 g were reared in 1100 L fibre-reinforced polyethylene tanks containing 1000 L of 10 ppt saline water and a water depth of 0.9 m. Leaf litter with or without supplemental feed was applied to the tanks according to a 4 × 2 factorial design. The PLs were stocked at a density of 100 per tank and the experiment was conducted for 4 weeks without any exchange of water. Both mangrove species and feed application affected shrimp performance and water quality parameters except dissolved oxygen (DO), chemical oxygen demand (COD) and zoo-plankton concentration. The average survival rate of juvenile shrimp ranged from 86 to 94% in the treatments with both leaf litter and feed, 75–82% in the treatments with only leaf litter and 88% in the treatment with only feed. However, 100% mortality was observed in the treatment without any leaf litter or supplemental feed. Combined, leaf litter and feed resulted in 21 to 33% higher weight gain of shrimp PL than based on the combined contributions of leaf litter only or feed only, indicating synergism. Among the different mangrove species, S. apetala (23.1%) contributed the highest to total weight gain followed by A. officinalis (21.6%), S. caseolaris (21.6%) and H. fomes (10%). The lower feed conversion ratio (FCR) (0.18–0.27) in the treatments combining leaf litter and supplemental feed as compared to the feed-only treatment (0.41) indicated that leaf litter (directly or by stimulating natural food production) contributed to supplemental feeding. The growth of phytoplankton also appeared to contribute in low FCR as evidenced by a positive correlation (P < 0.001, r = 0.681⁎⁎) between phytoplankton concentration and shrimp weight gain. The synergistic effect between leaf litter and supplemental feed can help the farmer to minimize the shrimp production cost by lowering the feed input and enhancing mangrove three coverage on pond dikes as an inexpensive source of natural food.

Impact of the excitation frequencies on wall stresses in a storage tank

This research addresses the experimentally determined relationship between the excitation frequency and both hoop and axial wall stresses in an upright water storage tank. A low-density polyethylene tank, utilising six water height to tank radius ratios (aspect ratios), was tested using a shake table. The tank is unrestrained at the base, i.e., uplift can occur. Harmonic excitations with eight frequencies that cover the dominant frequencies of recorded strong earthquakes were applied. Additionally, Ricker wavelet excitations of two different dominant frequencies, within the earthquake range, were considered. The maximum wall stresses calculated from experimental data and those from a nonlinear elastic spring-mass model were compared. The results reveal that, under low dominant-frequency excitations, the sloshing behaviour governs the development of wall stresses. In contrast, under high-frequency excitations, uplift determines the wall stresses. Uplift and sloshing occur simultaneously, and the contribution of each of these factors to wall stresses depends upon the aspect ratio and both the frequency and acceleration of the excitation. The spring-mass model tends to overestimate both hoop and axial stresses when the aspect ratio is higher than two, regardless of the excitation frequency.

Reproduction and embryonic development in the African freshwater prawn Macrobrachium macrobrachion (Herklots, 1851)

The current study aimed to determine parameters and conditions for successful reproduction of Macrobrachium macrobrachion (Herklots, 1851) in a controlled medium and describing its embryonic development. A total of 122 adult specimens were collected from the delta of Oueme River and stored in polyethylene tanks with 1:2 male-female sex ratio. This broodstock was fed on pelleted food (Biomar Efico) once a day. For the embryogeny monitoring, eggs were sampled each hour through the first two days after spawning and then every 2 hours till hatching. Spawning happened at a mean temperature, dissolved oxygen concentration and pH of 27.80±0.56°C, 5.83±0.45 mg/L and 7.41±0.34, respectively. The eggs incubation meantime was 12±1 days with nine main embryonic development stages. Hatching lasted on the average 21.00±1.94 h and led to larvae with a mean size of 2.30±0.90 mm. Mean fecundity was 13062.4±5489.93 eggs and 14715.2±6108 eggs, respectively for the first and second seasons with a highly significant difference between them. The best hatching rates were obtained with salinities equal to 2 and 4‰. The results constitute the first database for larval breeding of M. macrobrachion species.

Brown seaweeds added in the diet improved the response to thermal shock and reduced Vibrio spp. in pacific white shrimp post‐larvae reared in a biofloc system

This work aimed to evaluate the effect of the combined use of the brown seaweeds Sargassum filipendula (S) and Undaria pinnatifida (U) dry biomass, as a feed additive, on growth performance, bacterial count and thermal shock resistance of Pacific white shrimp reared in a biofloc system during the nursery phase. Four combinations of seaweeds were evaluated: 0.5S:2U, 0.5S:4U, 1S:2U and 1S:4U (%), and a control diet. Shrimp post-larvae (PLs, initial weight ± 0.006 g) were reared for 7 weeks in 400 L polyethylene tanks, partially filled with water from a biofloc matrix tank, at density of 3000 PLs m−3, and were fed 6 times a day until reaching ±1 g. The presence of Vibrionaceae in PLs was significantly lower in those that were fed diets containing 0.5S:4U and 1S:4U. For thermal shock resistance (from 29°C to 13.5 ± 0.1°C for 1 h, and returned to 29°C), PLs fed the diet containing 1S:2U showed lower cumulative mortality than those fed the other diets. Among all treatments, no significant difference was observed in growth performance and total heterotrophic bacteria count in the PLs. S. filipendula and U. pinnatifida showed a combined effect on shrimp thermal resistance and reduction of Vibrio spp. in PLs.

Effects of carbon sources on the culture of giant river prawn in biofloc system during nursery phase

A six-week nursery culture of giant river prawn Macrobrachium rosenbergii was conducted in a zero-water exchange biofloc technology (BFT) system. Water quality, microorganisms, proximate composition and growth performance of prawn were compared by using five different carbon sources: wheat bran (WB), rice flour (RF), molasses (MO), maize starch (MS) and palm kernel expeller (PKE). These carbon sources were added at a carbon-nitrogen ratio of 15:1. Fifteen 125 L polyethylene tanks with water volume of 100 L were used for this experiment. Each tank was stocked with 100 postlarvae (average initial weight 21.9 ± 2.3 mg). Each treatment was randomly assigned in triplicate. The water quality parameters viz. temperature, pH, dissolved oxygen and ammonia-N did not differ (P > 0.05) among five different carbon treatments. MO based BFT system had significantly (P < 0.05) lowest nitrite-N and the highest biofloc volume than other treatments. The postlarval survival (88.6 %) was significantly higher (P < 0.05) in MS treatment and followed by RF (73.0 %), MO (68.3 %), WB (61.0 %) and PKE (56.3 %) treatments, respectively. Significantly (P < 0.05) better FCR (2.21) was obtained in MS treatment. The final weight, weight gain and specific growth were similar (P> 0.05) among the five treatments. Higher gross return, net return and benefit-cost ratio were obtained in MS group than WB, MO and PKE. Significantly (P < 0.05) the highest lipid (1.97 % dry weight) was obtained in MS bioflocs and followed by RF, WB, MO and PKE bioflocs, respectively. The present study indicated that MS carbon source for biofloc technology enhanced M. rosenbergii postlarval survival and growth.

Curcuma longa hydrolate improves Nile tilapia survival in a recirculation rearing system, maintaining the animal homeostasis and modulating the gut microbial community.

This study aimed to evaluate the effects of the dietary supplementation Curcuma longa hydrolate on Nile tilapia (Oreochromis niloticus) reared in a recirculation system. Hemato-immunological parameters, growth performance, nitrogen and phosphorus retention, as well as body composition and its interaction with the intestinal microbiota, were studied. Nile tilapia fingerlings (120) were distributed randomly in 8 polyethylene tanks (40 L). The experimental units were divided into two treatments, in quadruplicate: commercial diet supplemented with 2.5% of C. longa hydrolate and commercial diet without supplementation (control). After 45 days, the treatment supplemented hydrolate showed higher survival than the control group, 95.25% and 82.22%, receptively. In the blood profile, fish supplemented with hydrolate had a higher count of total leukocytes and neutrophils, as well as mean corpuscular hemoglobin and mean corpuscular hemoglobin concentration, than control group. The hydrolate group showed a substantial increase in the relative abundance of Cetobacterium and Romboutsia, as well as lower diversity in gut microbiota. The dietary addition of C. longa hydrolate for Nile tilapia seems to have a beneficial effect on gut microbiota, in addition to a likely positive effect on the physiological performance of Nile tilapia by maintaining intestinal homeostasis and promoting survival in reared conditions.

Effects of alfalfa (meal and extract) on digestive enzymes and liver composition in juveniles of common carp (Cyprinus carpio)

270 fish (with an average initial weight: 20.04±0.19 g) were randomly distributed in 27 polyethylene tanks and fed by the carp commercial diet. The experimental treatments of 9 groups (4 groups with 3, 6, 9, and 12% of alfalfa powder, 4 groups with 1, 2, 3, and 4% of alcoholic extract and one control group) with three replications were considered for 8 weeks. At the end of the experimental period, the activity of digestive enzymes was measured in terms of U/mg Protein and liver composition. Based on the results, the highest levels of activity of digestive enzymes, amylase (674.74±61.57), lipase (6/21±/096), alkaline phosphatase (452.84±28.18), trypsin (282.05±19.98) and chymotrypsin (0.10±0.001) in the extracts of 3%, 3%, 3%, 4% and 4% extracts, respectively, and the lowest amount of these enzymes were observed respectively with values of 388.17±38.27 (control), 2.51±0.55 (control), 187.7±19.36 (12% powder), 0.030±0.004 (12% powder) and 132.47±11.47 (9% powder) (P <0.05). The highest amount of hepatic glycogen (338.35±192.13 µg/g tissue) was measured in the 3% extract treatment and the lowest amount of hepatic glycogen (607.01±101.23 µg/g tissue was in the control treatment (P <0.05). The highest level of liver lipids (146.51±6.05 mg/g tissue) was observed in the treatment of 6% powder and the lowest level of liver lipids (72.99±4.46 mg/g tissue) was observed in the treatment of 12% powder (P <0.05). According to the present study, adding powder and especially alfalfa extract to the diet can increase the activity of digestive enzymes and increase liver lipid and glycogen at certain levels.

Sex disparities determined by biometric and hematological measurements in Astyanax bimaculatus

ABSTRACT This study aimed to compare the body indexes and hematological characteristics between Astyanax bimaculatus males and females. Four hundred fish were randomly distributed into four polyethylene tanks (100 fish/unit) in a recirculation system and fed four times a day (3% of biomass). After 90 days, ten fish (five ♀ and five ♂) were removed to perform blood tests and to measure weight, height, total length, height/length ratio, condition factor and index determination: vicerosomatic (VSI), hepatosomatic (HSI), and gonadosomatic (GSI). The results showed a higher average weight (g) in females (12.32±0.71) compared to males (6.98±0.75), the same happened to height (cm) = (3.01±0.07) and (2.40±0.05), total length (cm) = (3.01±0.07) and (2.40±0.05), VSI (%) = (11.43±0.81) and (3.55±1.05), HSI (%) = (0.72±0.08) and (0.30±0.04), respectively. Mean corpuscular hemoglobin (pg) was higher in females (3.72±1.20) than in males (2.99±1.51). Regarding the number of thrombocytes (103.µL-1), there was an increase in males (25.71±3.91) compared to females (17.40±6.40).

Effect of different levels of dietary Sargassum cristaefolium on growth performance, hematological parameters, histological structure of hepatopancreas and intestinal microbiota of Litopenaeus vannamei

The effects of Sargassum cristaefolium dry biomass as a feed supplement on growth performance, hematological parameters, histology of hepatopancreas, and intestinal microbiota of Litopenaeus vannamei post larva were examined. Shrimp (0.011 ± 0.001 g) were fed diets containing different levels of S. cristaefolium powder (0 g/kg for the control group and then 5 g/kg, 10 g/kg, 20 g/kg, and 40 g/kg w/w for experiment groups). The animals (40 shrimp per tank) were stocked in 300 l polyethylene tanks in triplicate for 60 days. After 60 days feeding trial, the shrimp fed Sargassum powder showed no significant difference in growth performance compared to control group (p > 0.05). The B-cells number in the hepatopancreas of shrimp fed 10 and 20 g/kg of S. cristaefolium diets were significantly lower than those of shrimp fed the control diet. The highest prevalence of R-cells was observed in 10 and 20 g/kg groups, respectively (p < 0.05). The shrimp fed 40 g/kg S. cristaefolium had the lowest cholesterol level compared to other groups. The triglyceride level of shrimp in the S. cristaefolium diets was lower (59% - 65%) than that of shrimp in the control diet. No significant difference in the phosphorus, total protein, albumin, alkaline phosphatase (ALP), aspartate aminotransferase (AST), and alanine aminotransferase (ALT) levels were observed with any dose (p > 0.05). The total viable bacterial and Vibrio counts in the intestine of shrimp were gradually decreased when the level of S. cristaefolium was increased (p < 0.0001). Total hemocyte count (THC) in the shrimp fed S. cristaefolium diets was significantly higher than that of the shrimp fed control diet (p > 0.05). The present study indicated that shrimp fed diets containing S. cristaefolium can significantly improve hematological parameters, R.cells, and inhibit Vibrio spp. in the intestine of L. vannamei.

Changes in growth, orexigenic hormones and blood metabolites following short‐term food deprivation and refeeding in juvenile Asian sea bass (Lates calcarifer)

Changes in growth, blood metabolites and blood ghrelin and leptin levels were investigated in Asian sea bass (Lates calcarifer) subjected to short-term food deprivation and refeeding. After two weeks of acclimation, 144 fish, weighing 35 ± 5 g, were randomly assigned to twelve 300-litre polyethylene tanks and were fed to satiation twice daily (10:00a.m. and 17:00pm) using a commercial diet for 24 days. The experimental design included four treatments with three replicates each: 2, 4 and 8 days food deprivation followed by 16 days refeeding and a control group without food deprivation. Growth parameters did not show any significant change at the end of the experiment. Plasma ghrelin levels increased significantly after 4 and 8 days food deprivation (p ˂ .05). Food deprivation resulted in lower plasma leptin levels whereas refeeding led to an increase in leptin. No significant difference in leptin levels was observed between the treatments. An increase in triglyceride and a decrease in blood glucose levels were observed during the fasting period. At the end of refeeding period, the plasma protein did not show any significant variation among the treatments. Our results demonstrate the ability of L. calcarifer juveniles to adapt well to food supply after a period of food deprivation which could be associated with the status of appetite-regulating hormones such as ghrelin and leptin.

The effects of different solids and biological filters in intensive pacific white shrimp (Litopenaeus vannamei) production systems

Biofloc systems rely on suspended solids in the water to house microbes that can remove or cycle nitrogenous wastes; however, nitrogen cycling can be inconsistent. In contrast, external biofilters are used in many recirculating systems to provide a more consistent environment for microbes to process nitrogen. Regardless of the biofiltration approach, solids levels must be controlled to prevent issues in shrimp such as gill fouling, low dissolved oxygen levels, and other negative impacts. The purpose of this study was to examine the effects of settling chambers versus foam fractionators for solids filtration and to compare external biofilters to the biofloc approach as biofiltration strategies. Sixteen 1-m3 round, polyethylene tanks were randomly assigned to four treatments, each of which had four replicate tanks. Eight biofloc systems were established: four using settling chambers for solids control (BF-S) and four using foam fractionators (BF-F). The other eight tanks used external biofilters; four had settling chambers (EB-S) and the other four had foam fractionators (EB-F). All 16 systems were stocked with 250 shrimp at an average size of 4.3 g which were grown for 85 days. There were no significant differences in shrimp production between treatments; however, variability was high in biofloc systems. Nitrite levels were significantly lower in systems with fractionators compared to systems with settling chambers. The concentrations of dissolved Na, Mg, Ca, Sr and Ba in the water were significantly reduced in treatments with settling chambers. The results of this study show that filtration choices significantly impact short- and long-term water quality and reusability but may not have much effect on shrimp production in the short-term.

Glutamine use in feeding juvenile pirarucu, Arapaima gigas (Schinz, 1822)

ABSTRACT This study aimed to evaluate glutamine supplementation effects on variables of growth performance, body composition, intestinal morphology and enzymatic aspects of juvenile Arapaima gigas. Research was conducted at the Fish Nutrition and Feeding Laboratory, where 60 examples of pirarucu (initial average weight of 82.12g) were distributed over 15 polyethylene tanks (310L), in a completely randomized design, with five treatments and three repetitions (four fish per experimental unit). Experimental diets were prepared containing five inclusion levels of the amino acid glutamine (0.0, 0.5, 1.0, 1.5 and 2.0%), supplied three times a day for 45 days. Quadratic effect was observed for the variables of growth performance, weight gain, food consumption, food conversion, and specific growth and protein efficiency rates. A significant effect was observed on intestinal villi at the height of the anterior portion and on activity of the enzyme’s alkaline proteases, lipase, amylase and aspartate aminotransferase. However, glutamine supplementation had no significant effect on survival rate. Inclusion of 1.02% of glutamine in the diets of juvenile pirarucu improved growth performance and influenced intestinal villi height and activity of important digestive enzymes, favoring nutrient digestion and absorption.

Rainwater as an alternative drinking water source for the Chronic Kidney Disease Of Uncertain etiology (CKDu) prone areas: a case study for Girandurukotte, Sri Lanka

Abstract Chronic Kidney Disease of uncertain etiology (CKDu) is a fatal disease that causes death from kidney failure due to unknown risk factors and has already affected more than 400,000 people in the rural agricultural landscape (dry zone) of Sri Lanka. The major drinking source in Sri Lanka is groundwater and it is suspected that the pollution of groundwater sources due to agricultural means has a major impact on CKDu. The primary objective of this study is to determine whether rainwater can be used as an alternative safe drinking water source in Girandurukotte area, Sri Lanka, which is known to be an area endemic for CKDu. The physical, chemical, and biological analyses were performed to compare the water quality parameters of three water sources (groundwater, surface water, and rainwater) for Girandurukotte area. The most common storage tanks in polyethylene (PE) and ferrocement (FC) were compared to assess the influence of the material of rainwater tank on water quality. The results showed that there is a significant difference in rainwater in terms of water quality compared to groundwater and surface water. Rainwater in FC and PE tanks showed significant differences (p &amp;lt; 0.05) for some parameters however, they were still within accepted potable drinking water standards.

Design and performance of a low-cost, automated, large-scale photobioreactor for microalgae production

Microalgae feed production is a major cost in bivalve aquaculture. Its efficiency is increased by scaling it up under automated control of environmental conditions. The initial cost of commercially available systems can be prohibitive. Therefore, a large volume full-scale photobioreactor built of low-cost, readily available materials was developed and tested. A cone-bottom, polyethylene tank was internally illuminated with submersible fluorescent lamps and equipped with a monitoring and control system that measured temperature, pH and optical density of the microalgal culture. Injection of CO2 was automated to maintain pH within a target range. System performance was evaluated by growing four batch cultures of Tetraselmis chuii. Temperature inside the photobioreactor was 29.5 ± 2.38 °C (mean ± SD, range 21−35 °C) and pH was 7.56 ± 0.87 (mean ± SD, range 5.29–8.97). Optimal harvest time was after 300 h (12.5 days) of growth, yielding 1700 L of microalgae at a density of 2500 cells/ μl (1200 cells/ μl/ m2 illuminated surface area). With 24 h illumination, the fluorescent lights, air pump and monitoring/ control device consumed 14.9, 1.9 and 0.1kwh/ day, respectively. Assuming the microalgae are harvested at their optimal density after 12.5 days, each batch would consume 211kwh or 0.124kwh/ liter. The photobioreactor described provides an economical option for growing large amounts of microalgae for aquaculture feed and other purposes.