Published on 23/3/2017
A feeding trial was conducted to evaluate dietary protein and lipid requirements for juvenile largemouth bass, Micropterus salmoides. A 4 × 2-factorial layout included four protein (420, 450, 480, and 510 g/kg) and two lipid (80 and 120 g/kg) levels. Fish (initial weight 8.7 g) were fed the test diets for 8 wk. Weight gain, feed intake, feed conversion ratio, hepatosomatic index, and body composition were dependent on dietary protein level. Nitrogen retention efficiency was independent of dietary protein level, lipid level, and their interaction. Weight gain was higher in fish fed the diet containing 480–510 g/kg crude protein than in fish fed the diet containing 420–450 g/kg crude protein at two dietary lipid levels. The feed intake and weight gain were higher in fish fed the diet containing 484 g/kg crude protein and 115 g/kg crude lipid than in fish fed the diet containing 478 g/kg crude protein and 77 g/kg crude lipid. This study indicated that the suitable dietary protein and lipid levels for largemouth bass are 480–510 g/kg and 120 g/kg, respectively.
Published on 23/3/2017
The US regulatory environment has been characterized as complex due to the greater than 1300 laws promulgated at local, state, and federal levels. Recent declines in the growth rate of US aquaculture have been attributed, in part, to a complex, overlapping, and inefficient regulatory framework. This study is the first to examine this question by quantifying the farm-level regulatory burden and its economic effects in an aquaculture industry sector. A survey was conducted of baitfish and sportfish producers in the 13 major production states in the USA to identify the direct and indirect costs of regulation on producers. Survey responses captured 74% of the national volume of baitfish and sportfish production. The data revealed that only 1% of total regulatory costs are direct costs of regulation, such as license and permit fees, while 99% of the costs are due to manpower used for compliance, farm changes to remain in compliance, and sales lost without replacement. Costs due to regulations varied across states and farm sizes. Across all respondents, average total regulatory costs were found to be $148,554/farm, or $7383/ha. The farm-level cost to the US baitfish and sportfish industry was estimated to be in excess of $12 million. On 38% of the farms, the cost of regulations exceeded the value of profits on baitfish and sportfish farms. Our findings confirm previous reports of the complexity of the regulatory environment. Results show that the total regulatory burden has increased farm-level costs and restricted access to markets, thereby reducing profitability and contributing to reduced growth of the US baitfish and sportfish industry.
Published on 22/3/2017
This study estimated the heritabilities of growth-related traits in Paralichthys olivaceus using a microsatellite-based pedigree. A set of 48 microsatellite markers located at different regions of each linkage group were selected from the published genetic map. The flounders used here originated from the Bohai Sea and the broodstock was mated to produce 10 full-sib families. The resulting fish were assayed to obtain the probabilities of exclusion (Excl 1 and Excl 2) for each marker. Sixteen markers showed low Excl 1 and Excl 2 values, eight had high probability values, and the remainder showed intermediate probability values. A marker-based pedigree of four full-factorial crosses (FFCs) was constructed using the eight markers with high Excl 1 and Excl 2 probabilities. Body measurements (such as body weight and total length) were determined in 752–943 individuals from the FFCs at 200, 400, and 500 d of age. An animal model was used for single-trait analyses and estimated moderate heritabilities, ranging from 0.23 to 0.48. These results demonstrate that markers with high exclusion probabilities provide an efficient tool for parentage assignments and genetic analyses in Japanese flounder. Marker-assisted estimation of heritability is an efficient approach to genetically improve growth traits in this species.
Published on 17/3/2017
Although taurine has been identified as a required nutrient in several Seriola species, there are no available quantitative data on dietary taurine requirements for these commercially important species and recommendations are highly variable. Therefore, juvenile Seriola lalandi were fed one of eight practical diets supplemented with graded levels of taurine (0.11–1.08% of the dry diet, analyzed) to estimate their taurine requirement. Response in growth rate, feed efficiency, and nutrient deposition were evaluated using a broken-quadratic model and 4- and 5-parameter saturation kinetic models (4-SKM and 5-SKM) Blood serum composition was analyzed using linear models. Requirement estimates based on growth rates (thermal-unit growth coefficient) and protein deposition were similar at 0.26% (95% confidence interval [CI]: 0.23–0.28) and 0.29% (95% CI: 0.25–0.34) dietary taurine, respectively. Feed and protein deposition efficiencies were optimized at 0.26–1.02% and 0.26–1.00% dietary taurine, respectively. Taurine deposition in the animal was maximized at higher dietary levels (0.64%). Levels of serum taurine increased in response to dietary levels and peaked at around 0.80% dietary taurine. Concomitantly, serum urea and total amino acid levels decreased with increasing dietary taurine levels, suggesting a reduced amino acid catabolism relative to the aforementioned improvement in protein deposition efficiency.
Published on 14/3/2017
A feeding trial was conducted to evaluate the potential of replacing fishmeal with poultry byproduct meal (PBM) and soybean meal in diets for largemouth bass, Micropterus salmoides. A reference diet (C) contained 400 g/kg fishmeal, and 40 or 60% of the fishmeal was replaced with a blend of pet-food-grade PBM and soybean meal (diets PP1 and PP2) or a blend of feed-grade PBM and soybean meal (diets PF1 and PF2). No significant differences were found in weight gain, nitrogen retention efficiency (NRE), condition factor, and body composition among fish fed diets PP1, PP2, PF1, and PF2. Feed intake and feed conversion ratio (FCR) were higher in fish fed diet PF1 than in fish fed diet PP1. No significant differences were found in weight gain, NRE, condition factor, and body composition between fish fed diet C and diets PP1, PP2, PF1, and PF2. The feed intake and FCR were lower in fish fed diet C than in fish fed diets PP2, PF1, and PF2. This study reveals that dietary fishmeal level for largemouth bass could be reduced to 160 g/kg by inclusion of PBM and soybean meal in combination.
Published on 8/3/2017
The aim of this study was to investigate effects of dietary geniposide (GP) on growth performance, flesh quality, and lipid metabolism of grass carp, Ctenopharyngodon idella (95.2 ± 0.6 g), fed seven different diets, including a control diet; Eucommia ulmoides (EU)–supplemented diet (20 g/kg); and GP-supplemented diets containing 100, 200, 400, 600, and 800 mg/kg GP, respectively. Weight gain rate was significantly improved (P < 0.05) and feed conversation ratio was significantly decreased (P < 0.05) by supplementation of EU. Grass carp fed 100–800 mg/kg GP-supplemented diets showed significantly higher total collagen and alkaline-insoluble collagen content in muscle than control (P < 0.05). Contents of total collagen and the alkaline-insoluble collagen content in the skin of grass carp were significantly increased by dietary 600–800 mg/kg GP and EU (P < 0.05). Fish fed diets containing 600–800 mg/kg GP showed significantly lower muscle crude lipid content than the EU, control, and 100–400 mg/kg GP groups (P < 0.05). Fish fed 400–800 mg/kg GP diets had significantly higher muscle fiber density and lower muscle fiber diameter and serum triglyceride level than the control (P < 0.05). In conclusion, supplementation of GP could improve flesh quality, but not growth of grass carp. The supplemental level of GP for improving flesh quality was estimated to be a 400–600 mg/kg diet.
Published on 6/3/2017
A feeding trial was designed to assess the effects of dietary protein and lipid content on growth, feed utilization efficiency, body composition, and hematological indices of juvenile filefish, Stephanolepis cirrhifer. Eight experimental diets were formulated with a combination of four protein (35, 40, 45, and 50%) and two dietary lipid levels (7 and 14%). Each diet was fed to triplicate groups of fish (3.2 ± 0.06 g) to apparent satiation for 8 wk. Fish growth performance and feed utilization were significantly affected by increasing dietary protein and lipid levels, with no significant interactions between factors. The highest growth performance value, in terms of weight gain, was observed in groups fed the diets with 50% protein (399%). However, fish fed the diet containing 45% protein had comparable growth (357%) while achieving relatively higher protein efficiency ratio. Hepatosomatic index was significantly affected by interaction of dietary lipid and protein with the highest values observed in those fish fed the highest protein (45–50%) and lipid (14%) diets. There was a significant increase in body lipid content (5.1 to 6.6%) and a decrease in body protein (15.8 to 14.8%) and ash (2.47 to 2.16%) with increasing dietary lipid levels from 7 to 14%. Muscle lipid content was significantly affected by both dietary protein and lipid levels and tended to increase with increasing dietary protein and lipid levels, ranging from 0.13 to 1.20%. Liver lipid content (65.9 to 68.7%) was significantly increased with the increase in dietary lipid levels while liver moisture content (28.9 to 25.9%) showed a clear decreasing trend. Hematological values were also altered with the increase in either dietary protein or lipid levels. These findings may suggest that a diet containing 45% protein and 7% lipid, with a protein to energy ratio of 23.8 mg/kJ, could deliver sufficient nutrient and energy to support acceptable growth and feed utilization and avoid excessive fat deposition in juvenile filefish.
Published on 6/3/2017
The small-scale aquaculture (SSA) sector is recognized as making an important contribution to food security, poverty alleviation, and socioeconomic development. A value chain analysis can uncover insights into the linkages and trust within a value chain and constraints and challenges that face the sector. This paper examines the linkages and trust between SSA producers and traders in Asia in order to better understand the constraints and opportunities faced by small-scale producers. The perspective revealed by the value chain analysis provides response strategies that can enhance the sustainability and competitiveness of the entire value chain and the actors that comprise it.
Published on 2/3/2017
Two trials were conducted to estimate the methionine (Met) requirement of juvenile white seabass, Atractoscion nobilis. Diets were formulated to contain 40% crude protein, 10% lipids, and 0.51% cysteine. Graded levels of dl-Met were added to create seven diets with dietary Met levels ranging from 0.72 to 0.98%, and nine diets ranging from 0.64 to 1.28% Met in Trials A and B, respectively. Thermal-unit growth coefficient was fitted to dietary Met levels to estimate the Met requirement using the saturation kinetic model (SKM), the quadratic model (QM), or the broken quadratic model (BQM). The 95% confidence interval (CI) was estimated through the iterative fitting process for the BQM and using a bootstrapping approach for the QM and SKM. In Trial A, the three models estimated the requirement between 0.88 and 1.08%, with wide CI. In Trial B, precisions of the requirement estimates by the SKM and BQM were significantly improved compared with Trial A, though BQM evidently overestimated the requirement. SKM provided the best fit; hence, we conclude that the Met requirement for juvenile white seabass is 0.88% (95% CI: 0.80–1.08%) in the presence of 0.51% cysteine. This estimate provides valuable basis for the formulation of practical diets for juvenile white seabass.
Published on 2/3/2017
The aro genes in bacteria encode enzymes needed for the biosynthesis of aromatic amino acids, and mutant bacteria that are defective in the enzymes can replicate only a limited number in vertebrates owing to the lack or scarceness of chorismate, through which the mutant bacteria of the aro genes become attenuated. In the present study, the 5-enolpyruvylshikimate-3-phosphate synthase (aroA) gene-knockout Vibrio anguillarum (ΔaroA V. anguillarum) were generated by the allelic exchange method, and its vaccine potential was evaluated in the olive flounder, Paralichthys olivaceus, by comparing the protective efficacy of a formalin-inactivated V. anguillarum. The LD50 (50% lethal dose) value of ΔaroA V. anguillarum was 1000 times higher than that of wild-type V. anguillarum in olive flounder fingerlings, and the growth of ΔaroA V. anguillarum was significantly suppressed by coincubation with nonimmune olive flounder serum compared with that of wild-type V. anguillarum. The survival rates and serum agglutination titers of fish immunized with ΔaroA V. anguillarum were significantly higher than those of fish immunized with the same amount of formalin-inactivated V. anguillarum, suggesting that although the inactivated V. anguillarum vaccine can provide a high protection in olive flounder, the protective efficacy can be enhanced by immunization with an auxotrophic mutant ΔaroA V. anguillarum.
Published on 1/3/2017
Published on 28/2/2017
The cycling and fate of dissolved organic matter (DOM) in aquaculture systems are unique. Sanggou Bay, an aquaculture-dominated system in China, was chosen to characterize the composition of DOM based on optical properties. Field incubation experiments of eight mesocosms containing various aquaculture organisms were conducted in July 2013 to explore the impact of aquaculture organisms on the DOM composition. Dissolved organic carbon (DOC) showed an increasing trend, especially in integrated mesocosms, suggesting the accumulation of DOM in the aquaculture ecosystem. The DOC concentration was positively correlated with a280 (P < 0.01) rather than a355, demonstrating that a280 should be applied in the quantitative prediction of DOC in aquaculture systems. Parallel factor analysis was applied to identify the components of the excitation-emission matrix spectra. Two humic-like components and two protein-like components were identified. The significant correlation between the wet weights of the organisms and the humic-like component contents (P < 0.01) indicated that seaweeds and bivalves play important roles in the production of humic-like matter. The variation of protein-like materials was caused by the growth of aquaculture organisms and the decay of phytoplankton. The amount of bioavailable DOC (BDOC) derived from phytoplankton and organisms was estimated; bivalve organisms excreted more BDOC than did seaweeds. BDOC was significantly correlated with the protein-like components (P < 0.05) in the microbial incubation experiment.
Published on 23/2/2017
In this study, the performance of a spiral aerator, a modified design of the paddlewheel aerator, was evaluated to determine its applicability in aquaculture ponds. The aeration characteristics of the spiral aerator were determined by conducting aeration experiments in a cement concrete tank of dimension 5 × 5 × 1.5 m. Nondimensional numbers related to oxygen transfer (E) and power consumption (Ne) were proposed and expressed as functions of geometric (number of handles per shaft, n) and dynamic (Froude and Reynolds number) parameters. Simulation equations for oxygen transfer and power consumption based on the Froude criterion were developed. The maximum brake power standard aeration efficiency was achieved at n = 13. Finally, an economic analysis was performed assuming a typical Indian major carp culture pond to determine the optimum rotational speed of the aerator at different pond volumes and dissolved oxygen concentration present in the pond at which the aeration cost is minimized. The results showed that the least aeration cost is achievable when rotational speed of the spiral aerator is only 70 rpm for pond volumes up to 700 m3 and from 120 to 220 rpm for pond volumes exceeding 700 m3.
Published on 8/2/2017
The rising atmospheric carbon dioxide (CO2) concentration is increasing the solubility of limestone, calcium silicate, and feldspars, resulting in greater total alkalinity concentration in inland waters. This phenomenon will result in inland waters having slightly greater alkalinity concentration (and buffering capacity), higher pH when at equilibrium with atmospheric CO2, and more available carbon for photosynthesis. However, the changes in water quality will be small. Fluctuations in CO2 concentration resulting from CO2 use in photosynthesis by aquatic plants and release of CO2 by respiration, acidity resulting from nitrification of ammonia nitrogen from feeding waste and fertilizer, and application of liming materials to ponds will continue to be the dominant factors affecting pH and alkalinity in waters of inland aquaculture systems.
Published on 4/2/2017
For the purposes of this paper, biosecure shrimp feeds and on-farm feeding strategies refer to the “feed, whether live, fresh, or formulated, and the management of the feed on the farm, should not be an entry point of potential pathogens to the shrimp and/or to the culture system.” The paper reviews the different feeds commonly used for the production of farmed shrimp and discusses their potential risks from a disease perspective, including the use of live hatchery and nursery feeds, the use of live and/or fresh food organisms for the production of broodstock, and the use of dry formulated shrimp feeds for shrimp growout operations. In addition, the paper discusses the critical role played by feed-processing techniques for the pasteurization and destruction of pathogens within shrimp feeds and the need for nutritionists to formulate feeds for optimal nutrition and health, and not just for optimal growth. The importance of the development and implementation of good on-farm feed management practices by farmers is discussed, including the prohibition of the top-dressing of pelleted feeds on farm by farmers with unapproved feed additives such as antibiotics. Finally, the paper discusses the responsibilities of farmers, feed manufacturers, and traders regarding the development and use of recommended biosecure shrimp feeds and feeding practices.
Published on 2/2/2017
Integrated multitrophic aquaculture (IMTA) systems are designed mainly for efficient use of resources. Substrates added to aquaculture ponds provide space for periphyton to settle and recover nutrients, making these nutrients available to the species being reared. The present study is centered on the phosphorus budget, analyzing the main ecological compartments of IMTA systems in earthen ponds stocked with Amazon River prawn, Macrobrachium amazonicum, and Nile tilapia, Oreochromis niloticus, with or without different added substrates. The experimental design was completely randomized, with three treatments (without a substrate, with a geotextile fabric substrate, and with a bamboo substrate) and four replications. Phosphorus entered the systems mainly in tilapia feed (ca. 50–61%), inlet water (ca. 17–27%), and fertilizer (ca. 6–7%). Input of phosphorus from other compartments ranged from 1.5 to 1.9%. Most phosphorus was accumulated at the pond bottom as sediment (ca. 60–68%) and fish biomass (ca. 18–26%), or discharged in the outlet water (ca. 7–10%). Feeding is the main driver for the distribution of phosphorus in the ponds. Levels of phosphorus retained in reared animals (20–28%) were higher in these IMTA systems than in tilapia and prawn monocultures (reported as 10–20% and 10–13%, respectively). Nonetheless, the present data showed that the addition of different types of substrates might not improve the recovery of phosphorus in animal biomass as initially supposed. Even so, these IMTA systems decreased the amount of phosphorus released in effluents, and this decrease was enhanced by the addition of substrates, reducing the impact on the receiving waterbodies.
Published on 2/2/2017
In the pearl cultivation industry, the implantation of the nucleus is a critical step in the production process. The surgical insertion of the nucleus and the mantle results in a wound and stress that affect not only the survival chances of the pearl oysters but also the quality of the pearls produced. This study proposes a synthesized imidazole-dicarboxylic acid nickel complex that may hold potential in assisting the wound healing and nacre formation processes. The acute toxicity of the complex to pearl oysters, Pinctada martensii, was examined in a dose–response study over a 90-h exposure. The safe concentrations of the nickel complex determined using probit analysis were 0.916 mg/L and 0.471 mg/L for 72-h and 96-h treatments, respectively. The reliability of the regression was verified using the chi-square test. The alkaline phosphatase (ALP) activity in different regions of the treated and control oysters, along with relevant blood biochemical indices, were measured over a 90-d period to predict the potential effects of the nickel complex on wound healing and nacre formation. A significant increase in ALP activity in the mantle, together with elevated blood levels of Mg (II) and globulin, and reduced blood levels of Zn (II) and blood urea nitrogen were observed. These results indicate that the prepared nickel complex may hold promise in helping wound healing post mantle implantation, promote the secretion of nacre, and enhance the immunity of the oysters, thus ultimately improving the yield and quality of the pearls.
Published on 1/2/2017
Published on 1/2/2017
Published on 23/1/2017
A growth trial was conducted to evaluate the effect of a mixture of soybean meal and Chlorella meal (SCM) as a dietary fishmeal (FM) substitute on growth performance, apparent digestibility coefficients (ADCs), digestive enzymatic activities, and histology of juvenile crucian carp, Carassius auratus. Five isonitrogenous and isoenergetic diets were formulated to replace 0 (SCM0), 25 (SCM25), 50 (SCM50), 75 (SCM75), and 100% (SCM100) of protein from FM with SCM, respectively. The diets were fed to triplicate groups of juvenile crucian carp for 6 wk. Weight gain, specific growth rate, feed intake, protein efficiency ratio, and intestinal digestive enzymatic activities (amylase, trypsin, and lipase) tended to decline with increasing FM replacement levels (P > 0.05). Dietary SCM substitution significantly influenced dry matter content in muscle, and crude protein and lipid contents in liver (P < 0.05). ADCs for dry matter, protein, lipid, energy, and most amino acids showed no significant differences between the control and SCM25 group, but tended to decline with replacement levels over 25%. Higher SCM substitution (50–100%) caused karyopyknosis and necrosis in liver, but intestinal histology did not show noticeable pathological changes. The present study indicated that FM could be replaced by 25% of SCM, without significant adverse growth performance, feed utilization, and histology of crucian carp.