Showing papers in "Aquaculture Research in 2006"
TL;DR: The production performance and subsequent cost–benefit analyses clearly indicated that the diets containing probiotic biogen recorded the highest net return and the lowest total cost compared with the control diet.
Abstract: Probiotic microbial feed supplements are gaining wide acceptance in livestock production, and may be applicable to aquaculture production systems. The present study was conducted to examine probiotic treatment in the fingerling diet of Nile tilapia Oreochromis niloticus (L.). A total of 240 of Nile tilapia fingerlings (weight ranged from 22.96 to 26.40 g) were divided into five experimental groups. The experiment was conducted for 120 days. Experimental diets were identical in all, except for the variation in probiotic levels. A probiotic (Biogen®) was used at 0% (diet 1), 0.5% (diet 2), 1.5% (diet 3), 2.0% (diet 4) and 2.5% (diet 5) inclusion rates in the experimental diets. The growth performance and nutrient utilization of Nile tilapia including weight gain, specific growth rate, protein efficiency ratio, protein productive value and energy retention were significantly (P≤0.01) higher in the treatment receiving probiotic (Biogen®) than the control diet. No differences were observed for moisture, ash and protein content (P≤0.01) among the experimental diets. The lowest gross energy and lipid contents were recorded for fish fed the diet containing 0.5% Biogen® (P≤0.01). The production performance and subsequent cost–benefit analyses clearly indicated that the diets containing probiotic biogen recorded the highest net return and the lowest total cost compared with the control diet.
318 citations
TL;DR: It was found that the ability of different strains in degrading cellulose varies within a wide range, and might contribute towards better-feed formulation incorporating plant ingredients.
Abstract: Isolation and characterization of cellulase-producing aeorobic bacterial flora in the intestine of omnivorous tilapia (Oreochromis mossambica) and phytophagous Chinese grass carp (Ctenopharyngodon idella) have been carried out using selective carboxymethylcellulose-agar (CMC-agar) medium. The cellulolytic activity was measured both qualitatively and quantitatively. It was found that the ability of different strains in degrading cellulose varies within a wide range. Among the strains isolated from the gut of each test fish, TM1 and CI3 isolated from O. mossambica and C. idella, respectively exhibited maximum cellulolytic activity (67.02 and 35.8 U mL−1 respectively). Pure cultures of these strains were selected for morphological, physiological and biochemical characterization. On the basis of these tests, the isolated strains were identified as Bacillus circulans (TM1) and Bacillus megaterium (CI3). Both the strains are rod-shaped, motile and show better temperature (15–42°C) and pH (5–11) tolerance. The selected strains were further quantitatively assayed for amylase and protease activities. Maximum amylase and protease activities were exhibited by TM1 and CI3 respectively. Information generated from the present study might contribute towards better-feed formulation incorporating plant ingredients.
226 citations
TL;DR: The result suggests that B. subtilis can be used eiectively as a commercial product for use in aquaculture.
Abstract: Bacillus subtilis, a Gram-positive, aerobic, endosporeforming bacterium, was evaluated for its probiotic potential in Indian major carp, Labeo rohita. Labeo rohita (15 � 2 g) were fed a feed containing B. subtilis in three concentrations for 2 weeks, e.g., 0.5 (T2), 1.0 (T3) and 1.5 (T4) � 10 7 CFU g � 1 feed. The control group (T1) was fed feed without B. subtilis for the same period. Haematological and serum parameters were monitored at weekly intervals. The response variables were total erythrocyte count, total leucocyte count (TLC), haemoglobin, total protein, albumin, globulin, albumin^globulin ratio, alkaline phosphatase activity, alanine aminotransferase activity and aspartate aminotransferase activity. Fish were challenged intraperitoneally with a virulent strain of Aeromonas hydrophila after 2 weeks of feeding to the treatment groups and positive control group, while the negative control group was challenged with phosphate-buiered saline only. Clinical signs and symptoms, and mortality/survival percentage were noted in each group. The haematological and serum parameters were monitored each week and during post challenge on the third and tenth day. The B. subtilis-treated ¢sh (T4,1.5 � 10 7 CFU g � 1 feed) showed maximum per cent survival (87.50%), weight gain (35.5%), TLCs (3.23 � 10 4 cells mm � 3 ), haemoglobin content (7.4 g%), total protein (2.37 g dL � 1 ) and globulin content (1.28 g dL � 1 )d uring the pre-challenge. Enzymes showed higher activities during post challenge (Po0.05). The result suggests that B. subtilis can be used eiectively as a commercial product for use in aquaculture.
219 citations
TL;DR: In this study, the sizes, weight and biochemical contents of two copepods and one rotifer species raised on similar algal food conditions were compared and the FAA pattern of the preys tended to be species-speci¢c and its implications from an aquaculture point of view is discussed.
Abstract: The use of live prey is still necessary for a large number of raised ¢sh species. Small sized rotifers are usually used as live preys during the ¢rst days of feeding in small mouth ¢sh. An alternative to this is the use of copepods as prey for ¢rst feeding. In this study, the sizes, weight and biochemical contents of two copepods and one rotifer species raised on similar algal food conditions were compared. Rotifers contained a higher proportion of essential amino acids in the free amino acid (FAA) fraction (43%) than copepods (30^32%). However, rotifers had lower levels of important fatty acids like DHA (7% compared with 23^32% in copepods) and their DHA/EPA ratio was lower than that in copepods (0.54 compared with 1.35^1.63 in copepods). The FAA pattern of the preys tended to be species-speci¢c and its implications from an aquaculture point of view is discussed. In contrast, the-protein bound amino acids tended to be very conservative among the studied organisms. The second part of the work is focused on ‘the price’ of hatching in Acartia tonsa eggs before or after cold storage at 31C. The fatty acid contents in A. tonsa tended to decrease with the storage time. It also decreased with hatching of the nauplii, but its proportion compared with the dry weight remained constant.
143 citations
TL;DR: Electron microscopical analysis of hindgut regions confirmed traditional culture-based microbial analysis as fewer bacterial cells were observed between microvilli and associated with the surfaces of enterocytes of fish fed inulin rather than dextrin.
Abstract: The primary aim of the present study was to evaluate the population level of adherent (autochthonous) aerobic and facultative anaerobic bacteria in the hindgut of healthy Arctic charr (Salvelinus alpinus L.) fed dextrin or inulin. This was assessed by the dilution plate technique, and visualized using both transmission and scanning electron microscopy. A population level of 4.8 × 105 adherent bacteria per gram wet mass was found in the hindgut of fish fed a casein-based diet supplemented with 15% dextrin. However, substituting dextrin with 15% inulin reduced the bacterial population level in the hindgut (3.56 × 104). A total of 217 bacterial isolates were identified by key phenotypical and biochemical characteristics. In addition, 22 strains were also identified by partial sequencing of the 16S rRNA gene. The composition of bacteria colonizing the hindgut of Arctic charr fed dextrin was dominated by the genera Staphylococcus, Pseudomonas, Micrococcus, Psychrobacter glacincola and Streptococcus. However, bacteria colonizing the hindgut of fish fed inulin were dominated by Gram-positive bacteria of the genera Staphylococcus, Streptococcus, Carnobacterium and Bacillus. While Carnobacterium divergens-like strains were isolated from charr fed dextrin, Carnobacterium maltaromicus-like strains were isolated from the hindgut of fish fed inulin. Electron microscopical analysis of hindgut regions confirmed traditional culture-based microbial analysis as fewer bacterial cells were observed between microvilli and associated with the surfaces of enterocytes of fish fed inulin rather than dextrin.
143 citations
TL;DR: The effects of feeding level on growth and energy partitioning were studied in rainbow trout growing from 150 to 600 g and showed that the widely used specific growth rate was not an appropriate model.
Abstract: The effects of feeding level on growth and energy partitioning were studied in rainbow trout growing from 150 to 600 g. Triplicate groups of fish (initial weight 158 g fish(-1)) were fed a practical diet at various feeding levels (25%, 50%, 75% and 100% of near satiation) for 24 weeks at 8.5 degrees C. The final body weights of fish were 235, 381, 526 and 621 g. Restricted feeding levels significantly reduced live weight gain. Feeding levels had less pronounced effects on feed efficiency ratio, which were 0.98, 1.08, 1.02 and 0.83, respectively, for the 25%, 50%, 75% and 100% feeding levels. The growth of fish fed to near satiation was accurately described by the thermal-unit growth coefficient. The growth data also showed that the widely used specific growth rate was not an appropriate model. Fish fed at the lowest feeding level (25%), which represented a maintenance ration (energy gain was less than 2 kJ fish(-1) day(-1)), showed positive protein deposition but negative lipid deposition. This indicates that fish fed a maintenance ration mobilize body lipid reserve to support protein deposition. The efficiency of energy for growth (k(g)) was estimated to be 0.63. The factorial multiple regression approach estimated that the partial efficiencies of metabolizable energy utilization for protein deposition (k(p)) and lipid deposition (k(f)) were 0.63 and 0.72, and that maintenance energy requirement was about 19 kJ (kg BW0.824)(-1), for rainbow trout held at 8.5 degrees C.
140 citations
TL;DR: The findings of this study demonstrated the superior growth performance of the improved strains at both densities compared with the non-improved strain, which could be more profitable for the tilapia farms in Kuwait than the lower density.
Abstract: This study was conducted to investigate the effect of stocking density (125 or 200 fish m−3) on the growth performance of three strains of the Nile tilapia, Oreochromis niloticus: the non-improved strain (NS), the genetically improved farmed tilapia (GIFT) and the Freshwater Aquaculture Center selected tilapia known as the FaST selected line (SL). Each strain and density combination was triplicated in 0.42 m3 fibreglass tanks within a re-circulating water system. Water temperature was maintained at 29.0±1.0°C. Large Nile tilapia having a mean body weight of 100–110 g were stocked in each tank and hand-fed four times daily with commercial tilapia pellets (35% protein) for 104 days. Results showed that at the two stocking densities, the GIFT and SL strains showed a significantly higher (P<0.05) mean weight (MWT), daily growth rate (DGR), specific growth rate (SGR), feed conversion ratio (FCR) and gross yield (GY) than the NS. In all three strains, growth performance was negatively affected by stocking density. The lower density (125 fish m−3) treatments had significantly higher MWT, DGR and SGR than the higher density one (200 fish m−3). However, higher FCR and GY were observed at the higher density. Survival rates were high in all treatments and were not affected by strain or density. In general, the SL strain had better growth parameters than the GIFT strain. The findings of this study demonstrated the superior growth performance of the improved strains at both densities compared with the NS. The higher density (200 fish m−3) could be more profitable for the tilapia farms in Kuwait than the lower density of (125 fish m−3) in terms of reduced land cost and facilities, demand on the limited low-salinity underground water and manpower.
116 citations
TL;DR: It is suggested that overall alien finfish species have done little ecological harm to native flora and fauna, however, in the wake of increasing anthropogenic development taking place in watersheds the resulting environments are often made unconducive to indigenous species but not to some alien species, thereby potentially and indirectly making the latter invasive.
Abstract: Asia dominates global aquaculture production accounting for over 80% of the total and the mainstay in Asian aquaculture is finfish. Over the years, Asia has experienced a number of inter-continental and intra-continental transfers/introductions/translocation of finfish species, between nations and watersheds, beyond their natural range of distribution, primarily for aquaculture development. In this article all such species are referred to as alien species. An attempt is made to evaluate the importance of the production of alien species in selected Asian nations, using statistics of the Food and Agriculture Organization. Also, negative effects, if any, based on literature surveys, of alien species in relation to displacement of indigenous species, and on biodiversity and/or genetic diversity together with associated pathogen transfers are evaluated. The major alien species, based on their significance to Asian inland aquaculture considered, are the tilapias, catfish, Chinese and Indian major carps and common carp. It is estimated that currently alien species account for nearly 12% of the cultured finfish production (2.6 million tonnes) in Asia, valued at US$ 2.59 billion, and the contribution exceeds 40% when Asian countries excluding China are taken into consideration. Inland finfish aquaculture in some Asian nations, such as Indonesia and the Philippines, is predominated by alien species, and in some others, e.g. Bangladesh and India, the contribution from alien species has been increasing steadily. It is suggested that overall alien finfish species have done little ecological harm to native flora and fauna. However, in the wake of increasing anthropogenic development taking place in watersheds the resulting environments are often made unconducive to indigenous species but not to some alien species, thereby potentially and indirectly making the latter invasive.
110 citations
TL;DR: Testing the hypotheses that dietary EO would increase tissue 20:4n-3 and 20:3n-6 and modulate immune function and eicosanoid production in juvenile Atlantic cod fed a diet where fish oil (FO) was replaced by EO found no significant differences in growth and feed efficiency, hepato-somatic index, percentages of liver and flesh lipids and lipid class compositions for cod fed FO and EO.
Abstract: Echium oil (EO) is a vegetable oil in which percentages of stearidonic acid (STA, 18:4n-3) often exceed those of its n-6 series equivalent γ-linolenic acid (GLA, 18:3n-6). Stearidonic acid is elongated to 20:4n-3 in fish cell cultures, suggesting that EO could be included in diets for marine fish to increase tissue 20:4n-3 and 20:3n-6 and, thereby, modulate eicosanoid metabolism. Thus, the present study aimed to test the hypotheses that dietary EO would increase tissue 20:4n-3 and 20:3n-6 and modulate immune function and eicosanoid production in juvenile Atlantic cod (Gadus morhua L.) fed a diet where fish oil (FO) was replaced by EO. Duplicate groups of juvenile cod (initial weight ca. 4 g) were fed for 18 weeks on fish meal-based diets (55% protein and 16% lipid) that differed in oil source (FO or EO). There were no significant differences in growth and feed efficiency, hepato-somatic index, percentages of liver and flesh lipids and lipid class compositions for cod fed FO and EO. Percentages of 18:4n-3, 18:3n-6 and 20:3n-6 in the total lipids of flesh and liver were higher, and percentages of 20:5n-3 and 20:4n-6 were both lower in fish fed EO than in those given FO. In flesh, the increased 18:3n-6 and 18:4n-3 were primarily located in phosphatidylcholine and, to a lesser extent, phosphatidylethanolamine, whereas 20:3n-6 concentration was highest in phosphatidylinositol. Desaturation of 18:3n-3 (to tetraene products) and 20:5n-3 to 22:6n-3 in hepatocytes was very low but was increased by dietary EO. Echium oil significantly decreased the production of prostaglandin F from gill cells stimulated with calcium ionophore A23187, and reduced head kidney macrophage activity, but had no effect on serum lysozyme activity or basic haematology. In conclusion, dietary EO may have beneficial effects on some immune parameters including eicosanoid metabolism in marine fish although this may be primarily because of decreased 20:4n-6 rather than increasing tissue levels of 20:3n-6 or 20:4n-3.
104 citations
TL;DR: It is demonstrated that zebrafish larvae can be reared without live food with a significant growth and a high survival, provided that an appropriate artificial diet is presented in a continuous way.
Abstract: Owing to the increasing importance of zebrafish as a vertebrate model in many fields of research, efforts must be made to breed and maintain this species in laboratory. Zebrafish larvae are traditionally reared on cultured live paramecia during the first 9 days of exogenous feeding, followed by a combination of paramecia and artemia nauplii until day 21, making larval rearing expensive, labour intensive and unpredictable. Thus, a trial was conducted with zebrafish larvae in order to evaluate the suitability of artificial diets as an alternative to live food during the first 21 days of exogenous feeding. Five dietary treatments were tested: (1) artemia nauplii; (2) a commercial; (3) a purified; (4) a practical diet, all delivered continuously; (5) the same practical diet delivered manually. The best overall larval performance was achieved in the group fed artemia nauplii (86% survival, 14.3 mm standard length, 46.1 mg wet weight). Compared with existing results obtained with the traditional live food schedule, our results suggest that paramecia might not be the most suitable first food for zebrafish, and that artemia nauplii could be used as the only live food. The present work demonstrates that zebrafish larvae can be reared without live food with a significant growth and a high survival, provided that an appropriate artificial diet is presented in a continuous way. Among the diets tested, the practical diet, if continuously delivered, led to the best performance assuring a mean standard length of 72% of that obtained with artemia and a similar survival rate. Moreover, the purified diet, supporting over 50% survival and an appreciable growth, could be useful in some toxicological studies in which a well-defined diet is needed.
101 citations
TL;DR: Selecting oysters for resistance to QX disease did not appear to confer resistance to winter mortality and the converse also applied.
Abstract: A breeding program for Sydney rock oysters Saccostrea glomerata (Gould, 1850) has been selecting oysters for resistance to QX disease (Marteilia sydneyi) and winter mortality (Bonamia roughleyi) for three generations at three sites in Georges River, New South Wales, Australia. The experimental sites are located at the upper, middle and lower reaches of oyster growing areas in the estuary. QX disease mainly occurs in the middle and upper reaches and is most severe at the latter. Winter mortality on the other hand occurs mainly at the lower and middle reaches and is most severe at the former. Progeny of third-generation Sydney rock oyster breeding lines were evaluated for resistance to both QX disease and winter mortality against a non-selected control. Line 1, selected for QX disease resistance at the upper estuary site, had excellent resistance to one season of exposure to disease, but suffered high mortality during the second season of exposure. However, these oysters had already reached market size of 50 g whole weight, with low mortality at 2 years of age, before the second episode of QX disease. Line 2 showed good improvement in resistance to both diseases, whereas Line 3, was the most resistant to winter mortality. Selection for resistance to QX disease did not appear to confer resistance to winter mortality and the converse also applied.
TL;DR: Triplicate groups of gibel carp Carassius auratus gibelio Bloch were fed for 8 weeks with nine isonitrogenous and isoenergetic diets and the effect of diet was found in whole-body moisture and fat content.
Abstract: Triplicate groups of gibel carp Carassius auratus gibelio Bloch (initial body weight: 4.89 g) were fed for 8 weeks at 24.8-30.8 degrees C with nine isonitrogenous and isoenergetic diets. The control diet (F1) used white fishmeal (FM) as the sole protein source. In the other eight diets (F2-F9), 40.5-100% of FM protein was substituted by poultry by-product meal (PBM) at 8.5% increments. The specific growth rate (SGR), feed efficiency ratio, protein efficiency ratio, protein retention efficiency and energy retention rate for fish fed PBM diets (F2-F9) were all higher, but not always significantly, than those for fish fed F1. All apparent digestibility coefficients for fish fed PBM diets were lower than those for fish fed F1. Fish fed F1 had a significantly higher hepatosomatic index value than fish fed PBM diets (P 0.05) effect of diet was found in whole-body moisture and fat content. Whole-body protein and energy content for fish fed PBM diets were slightly higher than that for fish fed F1. The optimal replacement level of FM by PBM was estimated by second-order polynomial regression to be 66.5% in protein.
TL;DR: Pesticide residues in the liver, gills and muscles of fish increased with increased pesticide concentrations in fish ponds, while total production, net returns and profitability of reared fish decreased with increasing of concentrations of pesticides.
Abstract: The effects of sublethal doses of dimethoate (20, 10 and 5 mg L−1) and malathion (2.0, 1.0 and 0.5 mg L−1) on growth parameters, haematological properties and total production of Nile tilapia (12.0 cm length and 40.0 g weight) and water quality were studied in fibreglass tanks (3 m2) for 24 weeks. Results showed that malathion compounds were more toxic than dimethoate. The sublethal toxicity of pesticides decreased plankton abundance and water quality in fish ponds. In comparison with controls, sublethal levels of these pesticides led to a significant decrease (P<0.05) in final body weight, specific growth rate and normalized biomass index of fish. The survival rate of Nile tilapia decreased with increasing concentrations of pesticides. Feed utilization (total food consumed, feed conversion ratio and protein efficiency ratio) varied with pesticide treatments. The erythrocyte count, haematocrit value and haemoglobin content of Nile tilapia were slightly decreased with increasing concentrations of pesticides. In addition, serum protein decreased, while serum glucose and lipid increased. Further, glycogen, protein and lipid in fish muscle gradually decreased with increased pesticide concentrations. Pesticide residues in the liver, gills and muscles of fish increased with increased pesticide concentrations in fish ponds. Their bioaccumulation in the liver was higher than in gill or muscle, which had the lowest residues for these pesticides. On the other hand, total production, net returns and profitability of reared fish decreased with increasing of concentrations of pesticides. Generally, sublethal concentrations of two pesticides in aquatic areas led to degradation of water quality and fish production in ponds.
TL;DR: It is concluded that a 1:1 blend of CO and PF is an excellent cost-effective dietary source of supplemental lipid for Atlantic salmon in sea water.
Abstract: This study assessed the suitability and cost efficacy of an equal blend of canola oil (CO) and poultry fat (PF) as a supplemental dietary lipid source for juvenile Atlantic salmon Quadruplicate groups of Atlantic salmon (∼400 g) held in 4000 L outdoor fibreglass tanks supplied with running (35–40 L min−1), aerated (dissolved oxygen, 788–104 mg L−1), ambient temperature (86–109°C) sea water (salinity, 26–35 g L−1) were fed twice daily to satiation one of three extruded dry pelleted diets of equivalent protein (488–493 g kg−1 dry matter) and lipid (267–274 g kg−1 dry matter) content for 84 days The diets were identical in composition except for the supplemental lipid (2347 g kg−1) source viz, 100% anchovy oil (AO; diet COPF-0), 702% AO and 298% CO and PF (diet COPF-30), and 403% AO and 597% CO and PF (diet COPF-60) Atlantic salmon growth rate, feed intake, feed efficiency, protein and gross energy utilization, percent survival and whole body and fillet proximate compositions were not affected by diet treatment Cost per kilogram weight gain was about 10% less for fish fed diet COPF-60 than for diet COPF-0 Percentages of saturated fatty acids in dietary and fillet lipids varied narrowly Moreover, percentages of 18:1n-9, monounsaturated fatty acids, 18:2n-6, n-6 fatty acids, 18:3n-3, and ratios of n-6 to n-3 fatty acids in the flesh lipids were directly related to the dietary level of CO and PF whereas 22:6n-3, the total of 20:5n-3 (eicosapentaenoic acid; EPA) and 22:6n-3 (docosahexaenoic acid; DHA), and n-3 fatty acids revealed the opposite trend Percentages of 22:6n-3, EPA and DHA, and n-3 fatty acids were significantly depressed in fish fed diet COPF-60 versus diet COPF-0 We conclude that a 1:1 blend of CO and PF is an excellent cost-effective dietary source of supplemental lipid for Atlantic salmon in sea water
TL;DR: The data suggest that diierent startfeeding diets may be important for long-term growth, incidence of deformities and quality of juvenile cod, and the use of zooplankton can greatly improve long- term growth andquality of cod juveniles.
Abstract: Growth, feed conversion e⁄ciency and frequencies of skeletal deformities were studied in juvenile Atlantic cod (Gadus morhua )t hat had been startfed on either rotifers (rotifer group) or zooplankton (zooplankton group). After metamorphosis, the ¢sh were reared at four constant temperatures (7, 10, 13, 161C) or moved successively from 16 to 13 and 101C (T-step, average 13.2 1C). The zooplankton group had a consistently higher growth rate at all the temperatures studied. Further, the zooplankton group had higher food intake (20%) and higher feed conversion ratio (1.65 vs. 1.31). In addition, a signi¢cantly higher incidence of skeletal deformities was found in the rotifer group (14.2%) compared with the zooplankton group (4.1%). After termination of the laboratory study, the ¢sh were reared in sea pens under ambient conditions for 17 months. Final weights of the zooplankton group were consistently larger (between 12% and 14% larger depending on original temperature groups). To verify the growth results, we conducted a follow-up study where a single egg group was divided into two parts and fed either on rotifers or zooplankton. This study indicated similar growth diierences as found in the ¢rst study. Overall, our data suggest that diierent startfeeding diets may be important for long-term growth, incidence of deformities and quality of juvenile cod. The use of zooplankton can greatly improve long-term growth and quality of cod juveniles. The study also highlights the advantage of using elevated temperatures in the juvenile phase as this will lead to signi¢cantly higher ¢nal weights in the adult stage.
TL;DR: The tradi tional technique of direct spore seeding onto inocula tion lines is abandoned and gametophyte cultures that were manipulated to enter gametogenesis and to produce synchronous batches of 10 4 10 5 embryos are used.
Abstract: Substantial amounts of Macrocystis and Lessonia are traditionally harvested and exported from Chile as raw material for alginate. Because of intense mari culture of abalone (Haliotis ssp.), herbivorous mol luscs that feed on brown kelps, pressure on local populations of Macrocystis and Lessonia has in creased to critical levels within the past 5 years, strongly supporting eiorts to produce algae maricul tured biomass. Here, we present our results on the de velopment of new techniques for large scale kelp mariculture in Chile. We have abandoned the tradi tional technique of direct spore seeding onto inocula tion lines. Instead, we used gametophyte cultures that were manipulated to enter gametogenesis and to produce synchronous batches of 10 4 10 5 embryos. Juvenile sporophytes were cultured under perma nent aeration and agitation, £oating unattached in contamination free glass bottles up to 10 L, plexiglass cylinders and 800 L greenhouse tanks. When hold fast initials were formed at a size of 8 cm, the sporo phytes were spliced into Nylon rope fragments and transferred to the sea. Twelve months after initiation of gametogenesis in the laboratory, Macrocystis pyrifera attained14 m length and 80 kg fresh weight m � 1 line in the sea. For Lessonia trabeculata 6m onths after gametogenesis initiation, 0.25 kg fresh weight m � 1 was attained in the sea.
TL;DR: Feeding white seabream on 15% dietary protein had a negative eiect on growth and feed utilization, and dietary lipid did not induce a protein-sparing action in Diplodus sargus juveniles.
Abstract: An 83-day feeding trial was carried out to determine the eiect of diierent dietary protein and lipid levels on the growth performances and carcass composition of white seabream. Juveniles (10.7 � 0.2 g) were fed to satiation on four diets, varying in protein (15% and 28%) and lipid (12% and 16%) levels. The best growth performance was observed in ¢sh fed on diets with higher protein level. Dietary lipids did not aiect growth performance. Voluntary feed intake decreased with a increasing dietary protein level at both dietary lipid levels. Feed conversion ratio improved with the increase in dietary protein and lipid levels. Carcass composition remained unaltered by dietary protein levels (P40.05). Carcass protein content tended to decrease, while lipid content tended to increase in groups fed on 16% lipid, compared with the 12% lipid groups. Additionally, protein retention was higher in ¢sh fed on low-protein and low-lipid levels, compared with the high-protein and high-lipid group (29% vs.19%). Lipid retention increased significantly with dietary protein level (Po0.001). Energy retention improved with dietary protein, but was not aiected by dietary lipid levels. On the basis of our results, feeding white seabream on 15% dietary protein had a negative eiect on growth and feed utilization. Dietary lipid did not induce a protein-sparing action in Diplodus sargus juveniles.
TL;DR: The major conclusion is that cod shows a high tolerance to the plant protein sources investigated in this experiment, and consequently that Atlantic cod safely can be fed diets holding up to 440 g kg−1 of the present investigated plant protein ingredients without any adverse effects on intestinal or liver function.
Abstract: This paper reports on the use of plant protein in cod diets, and where corn gluten meal, soybean meal, a mixture of these, or a mixture of wheat gluten meal and soy protein concentrate, substituted fish meal in a regression design up to 440 g kg−1 plant ingredients. Feeding lasted for a period of 20 weeks. High growth rates were obtained, and fish were able to maintain growth in all groups by increasing feed intake when plant proteins exerted high amounts of the protein fraction. This was confirmed by increased feed conversion ratio (FCR) values. The apparent digestibility measured by means of faecal stripping, showed high apparent digestibility coefficients (ADC) for fat, starch and protein. Small decreases in protein ADC and larger decreases in fat ADC were observed with high levels of plant protein ingredients. No histopathological changes were found, neither in liver nor in the different sections of the gastrointestinal (GI) tract, for any of the diet groups. Expression of stress genes (heat shock protein 70 and 90 (HSP70 and HSP90)) in liver showed no response to high levels of plant protein. Invasion of gut-bacteria in the distal part of the GI tract was substantial, but independent of diet level of plant ingredients. Gut evacuation analysis showed that the time for a meal to pass through the stomach and the GI tract was more than 72 h, with no variation dependent on diet plant protein level.
The major conclusion is that cod shows a high tolerance to the plant protein sources investigated in this experiment, and consequently that Atlantic cod safely can be fed diets holding up to 440 g kg−1 of the present investigated plant protein ingredients without any adverse effects on intestinal or liver function. There seems to be no gain if feeding frequency exceeds more than one large meal every 24 h at 6–7°C.
TL;DR: It was shown that the fatty acid composition of fish previously fed the vegetable oil diets returned to the average variability of the fillet fatty Acid composition of Murray cod after 70 or 97 days (LO and CO respectively).
Abstract: The dynamics of fatty acid composition modifications were examined in tissues of Murray cod fed diets containing fish oil (FO), canola oil (CO) and linseed oil (LO) for a 25-week period and subsequently transferred to a FO (finishing/wash-out) diet for a further 16 weeks. At the commencement of the wash-out period, following 25 weeks of vegetable oil substitution diets, the fatty acid compositions of Murray cod fillets were reflective of the respective diets. After transfer to the FO diet, differences decreased in quantity and in numerousness, resulting in a revert to the FO fatty acid composition. Changes in percentages of the fatty acids and total accumulation in the fillet could be described by exponential equations and demonstrated that major modifications occurred in the first days of the finishing period. A dilution model was tested to predict fatty acid composition. In spite of a general reliability of the model ( Y =0.9234 X +0.4260, R 2 =0.957, P X is the predicted percentage of fatty acid; Y the observed percentage of fatty acid), in some instances the regression comparing observed and predicted values was markedly different from the line of equity, indicating that the rate of change was higher than predicted (i.e. Y =0.4205 X +1.191, R 2 =0.974, P X is the predicted percentage of α-linolenic acid; Y the observed percentage of α-linolenic acid). Ultimately, using the coefficient of distance ( D ), it was shown that the fatty acid composition of fish previously fed the vegetable oil diets returned to the average variability of the fillet fatty acid composition of Murray cod after 70 or 97 days (LO and CO respectively).
TL;DR: The present study reveals that the optimum packing density for Indian major carp fry or transportation up to 6 h and metabolic regimes are species speci¢c during transportation.
Abstract: Glycogen content and metabolic enzyme activities viz. lactate dehydrogenase (LDH), malate dehydrogenase (MDH), aspartate amino transferase (AST) and alanine amino transferase (ALT) in Indian major carps, Labeo rohita, Catla catla and Cirrhinus mrigala, were investigated after a 6 h transportation trial to compare the species-speci¢c variation and the eiect of increased packing density on the metabolism. Fish (45 5m m, 0.5 0.1g) were packed in three densities (100, 150 and 200 L 1 ) for the experiment, and 12 specimens of each species were randomly sampled from all the treatments at the end of transportation. The glycogen content of L. rohita ingerlings decreased signi¢cantly (Po0.05) with increasing packing density. The activities of enzymes LDH, MDH, AST and ALT showed a rising trend with increasing packing density in all the three species. Species-speci¢c diierences were observed in various tested parameters at the lowest packing density (100 fry L 1 ). Alanine amino transferase and LDH activities were signi¢cantly (Po0.05) lower in C. mrigala as compared with the other two species. However, glycogen reserves and MDH activity were not signi¢cantly diierent (P40.05) among the species. The present study reveals that the optimum packing density for Indian major carp fry (100 fry L 1 )f or transportation up to 6 h and metabolic regimes are species speci¢c during transportation.
TL;DR: The economic analysis revealed that all-male monosex culture of M. rosenbergii was 63.13% and 60.20% more profitable than mixed and all-female cultures respectively.
Abstract: All-male monosex culture of Macrobrachium rosenbergii (De Man) has emerged as a popular practice in India, especially in the state of Andhra Pradesh. A study was conducted to compare the economics of all-male, mixed and all-female culture in 15 adjacent, rectangular ponds of 4000 m² each by stocking juveniles previously reared in a nursery for 60 days. The experiment was conducted using a completely randomized design with three treatments; T₁ (all male), T₂ (mixed) and T₃ (all female), and five replicates for a period of 5 months after the nursery phase. Statistical analysis showed highly significant (P<0.01) differences among the three types of culture. The cost of production was estimated and the economic feasibility of the culture methods was evaluated by cost-return and partial budgeting analysis. The average weight, productivity and specific growth rate were the highest for all male culture, being 80.92±2.41 g, 1532 kg ha⁻¹ and 1.97±0.02 respectively. All-female culture registered significantly higher survival (89.16±0.77%) and the best apparent feed conversion ratio of 1.26±0.02. The economic analysis revealed that all-male monosex culture of M. rosenbergii was 63.13% and 60.20% more profitable than mixed and all-female cultures respectively.
TL;DR: Diel and ontogenetic changes in larval body density related to swim bladder volume were investigated in Pacific bluefin tuna to determine the causality of larval mortality – adhesion to the water surface and contact with the tank bottom during seedling production.
Abstract: Diel and ontogenetic changes in larval body density related to swim bladder volume were investigated in Pacific bluefin tuna, Thunnus orientalis, to determine the causality of larval mortality – adhesion to the water surface and contact with the tank bottom during seedling production. The density of larvae with deflated swim bladders increased with total length and days post hatch. Diel density change was observed after day 2 post hatch; owing to daytime deflation and night-time inflation of the swim bladder, the density was relatively higher during the daytime. Increased swim bladder volumes clearly reduced larval density during the night-time after day 9 post hatch. However, the density of larvae with inflated swim bladders was greater than rearing water density (Δρ>0.0099). The small density difference between larvae and rearing water (Δρ=0.0022−0.0100) until day 4 post hatch may have caused larval mortality by adhesion to the water surface because larvae can be easily transported to the water surface by aeration-driven upwelling in rearing tanks. Density increased noticeably from day 5 to day 9 post hatch. The increased density difference (Δρ=0.0065−0.0209) in larvae and rearing water possibly induced mortality by contact with the tank bottom because larvae sink particularly during the night-time on ceasing swimming.
TL;DR: The thermoregulatory behaviour of green abalone Haliotis fulgens and pink abalone H. corrugata was investigated and the critical thermal maxima (CTMax) of H. fulGens and H. Corrugata were determined as a measure of thermal tolerance.
Abstract: The thermoregulatory behaviour of green abalone Haliotis fulgens and pink abalone H. corrugata was investigated. Haliotis fulgens juveniles ranging in wet weight from 3.0 to 3.3 g and from 28.7 to 30.5 mm shell length and of H. corrugata 2.0 g and 25.7 mm in shell length were exposed to 19°C for 30 days in a flow-through water system. Temperature preference was determined in a horizontal thermal gradient and was found to be 25.4°C for green abalone and 25.0°C for pink abalone. Displacement velocity was 4.3 cm h⁻¹ for H. fulgens and 12.8 cm h⁻¹ for H. corrugata. The optimum temperature for growth calculated for both abalone species was 24.6 and 24.5°C respectively. The critical thermal maxima (CTMax) of H. fulgens and H. corrugata were determined as a measure of thermal tolerance. Abalones were subjected to increasing water temperatures at a rate of 1°C on 30 min until they detached from the substrate. The CTMax at 50% were 33.6 and 32.0°C for green and pink abalone respectively. The results are discussed in relation to site selection and commercial rearing.
TL;DR: Immunohistochemical analysis showed that C. farreri TDO was located mainly in the cytoplasm of most cell types, suggesting that it is involved in various cellular processes.
Abstract: A Zhikong scallop (Chlamys farreri Jones and Preston 1904) tryptophan 2,3-dioxygenase (TDO) gene fragment, down-regulated by Vibrio anguillarum challenge, was isolated using mRNA differential display in our previous work. In this paper, the full-length TDO gene was cloned by 5′-RACE. Chlamys farreri TDO gene consists of 1292 nucleotides encoding an expected polypeptide of 383 amino acids with an estimated molecular weight of 44.8 kDa and an isoelectric point of 6.35. The deduced amino acid sequence is 54–61% homologous to TDOs from Caenorhabditis elegans, Mus musculus, Danio rerio, Homo sapiens and Drosophila melanogaster, and shares several histidine residues important for the enzyme function in other species. Chlamys farreri TDO is expressed in the mantle, gill, digestive gland, testis, adductor muscle and kidney. Immunohistochemical analysis showed that C. farreri TDO was located mainly in the cytoplasm of most cell types. The non-specific distribution of C. farreri TDO suggests that it is involved in various cellular processes.
TL;DR: The dietary protein and lipid requirements for female swordtails for optimized growth and reproductive performances to be at 30% and 12% respectively are indicated.
Abstract: We conducted a study to determine the effect of dietary protein and lipid levels on the growth and reproductive performance of a freshwater ornamental species, the swordtail (Xiphophorus helleri). Two protein levels (20% and 30%) with four lipid levels (8%, 12%, 16%, 20%) within each protein levels were tested through formulation of practical diets labelled as 20P8L, 20P12L, 20P16L, 20P20L, 30P8L, 30P12L, 30P16L and 30P20L respectively. Results showed that dietary protein level significantly influenced final weight, weight gain and specific growth rate, while dietary lipid did not influence any of these growth parameters. More specifically, increasing dietary lipid levels from 8% to 12–16% in both 20% and 30% protein levels significantly improved swordtail growth performance. Dietary protein levels positively influenced gonadosomatic and hepatosomatic indexes. Both dietary protein and lipid significantly influenced female muscle protein content. Significantly highest fry production was obtained from diets 30P12L and 30P16L, respectively, while diet 20P8L resulted in the lowest fry production. This present study indicates the dietary protein and lipid requirements for female swordtails for optimized growth and reproductive performances to be at 30% and 12% respectively.
TL;DR: Cod larvae originating from eggs of the advanced or delayed broodstocks were successfully reared beyond metamorphosis and survival correlated with both initial and average feeding conditions, but growth rate did not correlate with either of survival and feeding conditions.
Abstract: Commercial intensive fry production of Atlantic cod will be dependent on production of viable eggs independent of season. This can only be done by manipulation of maturation by photoperiod, but little is known about potential effects on egg characteristics and larval viability. In two cod broodstocks, maturation was successfully advanced or delayed 6 months compared with normal spawning season (March–April) by manipulation of photoperiod. The advanced broodstock spawned both in spring and autumn the same year. In two of the spawning tanks during autumn, ambient temperature was reduced after reaching 13.7°C during the first half of the spawning period. Egg quality and viability were monitored, and several egg batches were incubated, hatched and start-fed for examination of growth and survival. Temperatures above 9.6°C resulted in significant reductions in fertilization and normal egg development. Concurrently, fractions of dead and unfertilized eggs increased with elevated temperature. Actual relative fecundity was not affected by temperature. Egg characteristics improved when temperature was controlled and lowered below 9.6°C. Occurrence of irregular spawners suggests that handling of broodstock fish should be avoided during maturation and spawning. Cod larvae originating from eggs of the advanced or delayed broodstocks were successfully reared beyond metamorphosis. Survival was 9.0–46.6% and 29.3% in green and clear water respectively. Survival correlated with both initial and average feeding conditions, but growth rate did not correlate with either of survival and feeding conditions. Specific growth rates (8.3–13.6% day−1) is comparable with other intensive rearing trials with cod, but were lower than reported from nature-like systems.
TL;DR: The overall results obtained in this study suggest that the use of chicken manure produces better results than cattle and pig manure treatments on unfertilized ponds.
Abstract: An experiment was conducted to evaluate the eiect of using diierent types of organic manure on the plankton abundance, and growth and survival of Tilapia rendalli juveniles in ponds. Fish weighing18.15 0.44 g were stocked into 12, 20 m 2 ponds at 2 ¢sh m 2 (40 ¢sh pond 1 ). There were three replicate ponds per treatment (chicken manure, cattle manure, pig manure, and no-manure as a control). After 84 days the T. rendalli in the chicken manure treatment were signi¢cantly larger and had higher net annual yields than those in the cattle manure, pig manure and nomanure treatments. The survival rates were not signi¢cantly diierent across the treatments. Signi¢cantly higher amounts of chlorophyll a and higher numbers of zooplankton were found in ponds fertilized with the chicken manure treatment. The overall results obtained in this study suggest that the use of chicken manure produces better results than cattle and pig manure treatments on unfertilized ponds.