Final Individual Weight Research Articles

Common soluble carbohydrates affect the growth, survival, and fatty acid profile of black soldier fly larvae Hermetia illucens (Stratiomyidae).

The black soldier fly, Hermetia illucens (L. 1758), is an omnivorous saprophagous insect with a high potential for valorizing organic by-products rich in carbohydrates. Among carbohydrates, H. illucens relies on soluble sugars for the growth and storage lipid synthesis. This study aimed to assess the impact of common soluble sugars on the development, survival, and fatty acid composition of H. illucens. Monosaccharides and disaccharides were individually incorporated into a chicken feed diet. Cellulose was used as a control. Larvae fed glucose, fructose, sucrose, and maltose grew faster than control larvae. In contrast, lactose exhibited anti-nutritional effects on larvae, slowing down growth and reducing final individual weight. However, all soluble sugars produced larvae fatter than the control diet. Notably, the tested sugars shaped the fatty acid profile. Maltose and sucrose increased saturated fatty acid content compared to cellulose. Conversely, lactose increased the bioaccumulation of dietary unsaturated fatty acids. This study is the first to demonstrate the effect of soluble sugars on the fatty acid profile of H. illucens larvae. Our findings highlight that the tested carbohydrates have significant effects on black soldier fly fatty acid composition and can thus determine their final applications.

Optimizing feed restriction strategies for profitable Oreochromis niloticus culture in floating cages in riverine ecosystems

High feed cost is a major obstacle for promoting the growth of nutrient-rich fish species like Nile tilapia (Oreochromis niloticus) in cage aquaculture. To address this issue, cage farming of O. niloticus was studied for a 75-day period in the Gurukchi River of Bangladesh. Three different feeding strategies (FS) were tested in floating cages: FS5- weekly restriction on feed supply for two days, FS6- weekly restriction on feed supply for one day, and FS7- no weekly restriction on feed supply, with three replications for each treatment. Water quality parameters were monitored weekly and found within suitable levels for fish cultivation. The analysis of length–weight relationship and the condition factor of O. niloticus showed positive allometric growth regardless of the diverse feeding tactics employed that consistently exhibit stability across all treatments. Both FS6 and FS7 had significantly higher (p < 0.05) final individual length, final individual weight, net yield, total yield, and specific growth rate than FS5. FS6 yielded significantly higher fish production with significantly lower feed conversion ratio than FS7. Economic analysis revealed the highest benefit–cost ratio and net revenue in FS6, recommending its use to minimize the need for supplemental feed and reduce production costs in tilapia cage culture.

Performance Evaluation of Hydroponic Grow-Outs in An Innovative Coldwater Aquaponic System Featuring Rainbow Trout and Lettuce

A 45-day trial was carried out to assess the production performance of different hydroponic media in a novel do-it-yourself (DIY) low-tech re-circulating aquaponic system for temperate regions with rainbow trout (Oncorhynchus mykiss) and lettuce (Lactuca sativa). Rainbow trout juveniles (average weight of 35.59 g) were stocked in the experimental units at 2.8 kg.m-3 and fed with commercial floating pelleted feed at 8 % of their body weight in three treatments and a control. The lettuce saplings were randomly planted in the river stone bed (T1), crushed stone bed (T2), raft/deep water culture (DWC) unit (T3) and control (C) soil bed (fortified with NPK fertiliser) with equivalent planting intervals of 42 saplings.m-2. The system, designed with low-tech simplicity, was managed without alkalinity correction and depended entirely on plant growth and metabolism for biofiltration. The water quality parameters such as temperature, pH, dissolved oxygen (DO), dissolved free CO2, hardness, total alkalinity, ammonium, nitrite, and nitrate varied significantly (P &lt; 0.05) among the treatments compared to the control. The final individual weight, biomass gain, specific growth rate (SGR), and feed conversion ratio (FCR) of rainbow trout were significantly better (P &lt; 0.05) in media beds (crushed stone and river stone) compared to control and DWC systems. The final mean weights of rainbow trout in river stone (12.33 ± 0.002 g and crushed stone (12.39 ± 0.054 g) treatments were significantly higher (P &lt; 0.05) than in DWC (12.1 ± 0.023 g) and control (12.09 ± 0.002 g) treatments. The production of lettuce was significantly greater (P &lt; 0.05) in all three treatments (river stone: 4.33 ± 0.123 g, crushed stone: 4.53 ± 0.09 g and DWC: 4.31 ± 0.163 g) compared to the control (3.31 ± 0.172 g). The DWC including the media bed systems facilitates the improved performance of lettuce saplings in terms of final height and leaf number. These results show that a low-tech media bed system without a supplementary biofiltration unit can achieve sustainable production of both fish and vegetables in temperate hilly terrains.

Effects of stocking densities on tilapia seed production under high salinity biofloc system

Provision of suitable technique for saline tilapia seed is required since demand of these species increased continuously. Most saline tilapia seed rely on sourcing freshwater fingerling and further acclimatized in brackishwater ponds. The study aimed to evaluate the effects of various fry densities on seed production parameters of tilapia under high salinity-biofloc system. Three fry densities being tested and cultured under biofloc technology (BFT) at salinity level above 20 ppt, such as: A (BFT 2.5 fry L−), B (BFT 5.0 fry L−), C (BFT 7.5 fry L−) and one treatment as control, D (Non-BFT 2.5 fry L−). The experimental set-up was completely random design and triplicated replications. Animals test were fed two times a day of 32% crude protein content and it was lasted for three weeks. Results from the experiment shown that treatment A (BFT 2.5 fry L−) performed best in term of biomass (18.00±3.61g), survival (98.00±2.00%), SGR (20.72±0.20% d−), FCR (1.72±0.38) and CF (1.59±0.17). An increasing stocking density up 7.5 fry L− will reduced survival rate, final individual weight and increased FCR. It can be concluded that production of tilapia seed at a density of 2.5 fry L− under BFT conditions performed healthy seed and best production parameters even reared at higher salinity.

On demand feeding and the response of Pacific white shrimp (Litopenaeus vannamei) to varying dietary protein levels in semi-intensive pond production

Feed is one of the primary costs associated with commercial production of Pacific white shrimp (Litopenaeus vannamei). This high cost is the combined outcome of feed cost and feed management. As feeding technology evolves, specifically the use of automated feeding systems, it is vital to reevaluate the optimal protein levels in diets for the best production outcomes. The use of passive acoustic monitoring (PAM) adds another level of complexity to how shrimp respond to feed because it has the potential to automatically adjust feed offerings based on protein because of the shrimp's response. In this research, four diets with various protein levels (40, 35, 30, and 25%) were fed to shrimp which were stocked (0.045 g, 25 shrimp/m2) into 16 ponds (0.1 ha) and cultured for an 85-day production cycle. Shrimp were fed on demand using an automatic feeding system with passive acoustic feedback. Final individual weights were significantly smaller for shrimp fed the 25% diet (31.22 g) compared to all other diets. The total biomass of all ponds ranged from 6928 to 7878 kg/ha for shrimp offered the 25%- 40% diets, respectively. Other than final weight, analysis of total biomass and all other production data showed no differences between treatments (p > 0.05). Whole-body analysis revealed significant differences in fat (p = 0.0002), copper (p = 0.018), and apparent net protein retention (p = 0.0025). Analysis of economic values indicated a statistically significant difference between treatments for feed cost (p = 0.020). The significantly lower individual weights from shrimp fed the 25% diet and the notably lower total biomass resulted in a subsequent difference in class size distribution. This ultimately led to a difference in the market value of shrimp ranging from $60,383 to $71,247. Although the 40% protein diet was significantly higher in cost it showed no differences in production or economic outcomes and higher level of water born TAN as compared to the other diets. Overall, these results indicate that a 30–35% protein diet would be the most efficient for use in pond production of Pacific white shrimp under the culture conditions examined in this study.

Seroprevalence survey of anti-SARS-CoV-2 antibody and associated factors in South Africa: Findings of the 2020-2021 population-based household survey.

Population-based serological testing is important to understand the epidemiology and estimate the true cumulative incidence of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) to inform public health interventions. This study reports findings of a national household population SARS-CoV-2 serosurvey in people 12 years and older in South Africa. This cross-sectional multi-stage random stratified cluster survey undertaken from November 2020 to June 2021 collected sociodemographic data, medical history, behavioural data, and blood samples from consenting participants. The samples were tested for SARS-CoV-2 antibodies using the Roche ElecsysAnti-SARS-CoV-2 chemiluminescence immunoassay (CLIA) Total Antibody Test. The survey data were weighted by age, race, sex, and province with final individual weights benchmarked against the 2020 mid-year population estimates and accounted for clustering. Descriptive statistics summarize the characteristics of participants and seroprevalence. Logistic regression analyses were used to identify factors associated with seropositivity. From 13290 survey participants (median age 33 years, interquartile range (IQR) 23-46 years), SARS-CoV-2 seroprevalence was 37.8% [95% Confidence Interval (CI) 35.4-40.4] and varied substantially across the country's nine provinces, and by sex, age and locality type. In the final adjusted model, the odds of seropositivity were higher in women than in men [aOR = 1.3 (95% CI: 1.0-1.6), p = 0.027], and those living with HIV (self-report) [aOR = 1.6 (95% CI: 1.0-2.4), p = 0.031]. The odds were lower among those 50 years and older compared to adolescents 12-19 years old [aOR = 0.6 (95% CI: 0.5-0.8), p<0.001] and in those who did not attend events or gatherings [aOR = 0.7 (95% CI: 0.6-1.0), p = 0.020]. The findings help us understand the epidemiology of SARS-CoV-2 within different regions in a low-middle-income country. The survey highlights the higher risk of infection in women in South Africa likely driven by their home and workplace roles and also highlighted a need to actively target and include younger people in the COVID-19 response.

Evaluation of dietary α-lipoic acid supplementation on the growth performance and physiological status of striped catfish Pangasianodon hypophthalmus

This study aimed to evaluate the dietary supplementation of α-lipoic acid (ALA) on the growth performance, antioxidative capacity, and protein-sparring effect of striped catfish (Pangasianodon hypophthalmus) fingerling. The striped catfish (individual weight of 1.4 ± 0.0 g) were stocked in 25 cages at 2x1x1.5 m size in a 200-m pond at 50 fish. Fish were fed formulated diets with ALA supplementation, namely: diet A (27% protein: 390 kcal), diet B (27% protein: 390 kcal +ALA 8 g/kg), diet C (27% protein: 400 kcal), diet D (27% protein: 400 kcal +ALA 8 g/kg), and diet E (30% protein: 390 kcal). Feeding was performed until apparent satiation for 60 days. The ALA supplementation significantly produced higher final individual weight, specific growth rate, and protein efficiency ratio, followed by a lower feed conversion ratio on the 27:390+ALA diet treatment (P&lt;0.05) than other diet treatments. The highest liver performance based on superoxide dismutase enzyme activity and glycogen contents was obtained from the 27:390+ALA diet treatment. The malondialdehyde, triglycerides, and lipid accumulation in the liver on the 27:390+ALA diet treatment were lower than other diet treatments (P&lt;0.05). Therefore, the best growth performance and physiological status in striped catfish was obtained from 27:390+ALA diet treatment.

Combined Effects of Eco-Substrate and Carbon Addition on Water Quality, Fish Performance and Nutrient Budgets in the Pond Polyculture System

Traditional aquaculture can cause serious environmental pollution. Biofilm and biofloc technology have the potential to limit aquaculture pollution. An outdoor experiment was conducted to evaluate the combined effects of eco-substrates and carbon addition on water quality, fish performance and nutrient budgets in the pond polyculture system. In the treatment group, the total ammonia nitrogen, nitrate nitrogen, nitrite nitrogen, and total nitrogen of the water were significantly lower compared to the control group (p &lt; 0.05). The growth performance of H. molitrix and A. nobilis, including the final individual weight, specific growth rate, weight gain rate, total production and net production, was significantly higher in the treatment groups compared to the control (p &lt; 0.05), while there was no significant difference in those of C. carpio between the two groups. Feed was the main N (&gt;92%) and P (&gt;95%) input during the experiment. Comprehensive accumulation was the main N (&gt;58%) and P (&gt;69%) output. The N and P feed input and comprehensive accumulation output declined in the treatment group. The N utilization efficiency in the experimental group increased slightly (p &gt; 0.05), while the P utilization efficiency in the experimental group was significantly higher compared to the control (p &lt; 0.05). Therefore, the application of eco-substrates and carbon addition can increase water quality, improve fish growth, and promote nutrient utilization efficiency in pond polyculture systems.

Effects of Agro-Industrial Byproduct-Based Diets on the Growth Performance, Digestibility, Nutritional and Microbiota Composition of Mealworm (Tenebrio molitor L.).

Simple SummaryThe mealworm (Tenebrio molitor) is among the species considered to have the greatest potential to become a valid source of protein for consumption. In this study, mealworm larvae were reared on diets formulated with agro-industrial byproducts to evaluate the impact on their growth performance, digestibility, and nutritional composition as well as on the modulation of their gut microbiota profile. Depending on the diet composition, improvements were observed in the conversion rate (for diets with a smaller variety of byproducts and a higher starch content) or in the growth (for diets with a greater variety of byproducts and a higher protein content) of larvae. The diets also had repercussions for the gut microbiota profile and composition of the larvae. These results improve knowledge of the effects of byproducts used in mealworm larval rearing, which could contribute to their potential use in industrial-scale mealworm production.The aim of this study was to evaluate the effects of agro-industrial byproduct-based diets on the productive parameters, digestibility, insect composition, and gut microbiota of mealworm (Tenebrio molitor) larvae. Three formulations corresponding to three different levels of starch and protein were tested: one formulation based on bread remains and brewer’s yeast, representing a diet of high starch (61.1%) and low crude protein (18.5%) (HS-LP); and two formulations in which an additional four byproducts (courgette (Cucurbita pepo) remains, tigernut (Cyperus scelentus) pulp, brewer’s spent grains, and rice straw) were incorporated in different proportions, consistent with a diet of both moderate starch (29.8%) and crude protein (21.0%) (MS-MP); and another corresponding to a diet of low starch (20.0%) and high crude protein (26.3%) (LS-HP). A total of 1920 young larvae (average weight = 0.65 mg per larva) were used in this study. The larvae were randomly distributed into 16 replicates per treatment (boxes of 22.5 cm × 14.0 cm × 4.75 cm). Ten replicates for the growth performance–digestibility trial and six replicates for the complementary trial to determine uric acid levels in the frass were assigned per treatment. For growth performance, the diets were administered ad libitum during the experiment. The average number of days for the larvae to start pupating was lower in those reared on the HS-LP and LS-HP diets (88.90 and 91.00 days, respectively) than those on the MS-MP diet (120.09 days) (p < 0.001). The final individual weight was higher (p < 0.001) in larvae of the LS-HP group (168.69 mg) compared to those of the other groups (100.29 and 112.99 mg for HS-LP and MS-MP, respectively). However, the feed conversion ratio was better (p < 0.001) in the HS-LP group with the lowest value (1.39 g/g), with dry matter digestibility being the highest for the same diet (70.38%) (p < 0.001). Mealworms reared on LS-HP and MS-MP diets had a higher crude protein content than those reared on the HS-LP diet (p = 0.039). The most abundant phyla in the gut microbiota of larvae were Tenericutes, Proteobacteria, and Firmicutes, with their abundance depending on the rearing substrate. The representation of Tenericutes phylum was higher (p < 0.05) in the mealworms reared on MS-MP and HS-LP diets, whereas Proteobacteria and Cyanobacteria were higher in abundance (p < 0.001) in the insects reared on LS-HP. In conclusion, the larval growth, digestibility, insect composition, and gut microbiota of Tenebrio molitor were found to depend on the composition of the administered diet, and the results suggest great potential for the use of agro-industrial byproducts in their rearing and production.

Comparative juvenile performance assessment of genetically improved Nile tilapia ( Oreochromis niloticus L.) under commercial conditions in Bangladesh

Two on-farm juvenile performance trials were conducted at a hatchery in Bangladesh to compare a genetically improved strain of farmed Nile tilapia (GIFT) and a local strain (LS) produced by commercial operators. A 21-day early nursing trial was conducted in five replicate hapas followed by a 27-day advanced nursing trial in six replicate hapas. The mean feed conversion ratios (FCR), mean specific growth rates (SGR), mean individual final weights, mean production yields and mean survival rates were calculated for both strains. During the early nursing trial, GIFT fry survival rate and overall yield were significantly (p < 0.05) greater than LS values, which in contrast demonstrated better FCR and SGR. Improved performance was demonstrated in terms of FCR, SGR and yield for GIFT during the advanced nursing trial and mean final individual weights were 78% greater for GIFT than LS fish (2.26 g and 1.27 g respectively). Economic analysis indicated GIFT fish produced a net return 84% greater than that of LS fish at the end of the early nursing period, and by the end of the advanced nursing period, this difference had grown further such that GIFT generated a gross return over double that of LS. The results from a survey of tilapia grow-out farmers suggested producers from poor, medium and better-off backgrounds agreed GIFT performed better than traditional strains and is beneficial for aquaculture growth in Bangladesh. However, the results also indicate there may be a greater propensity for better-off farmers to appreciate the potential benefits of improved strains over poorer farmers.

The marine microbial biomass, Novacq™, a useful feed additive for postlarvae and juvenile Litopenaeus vannamei

Although Litopenaeus vannamei is the most produced and researched shrimp species worldwide, there are no published studies evaluating the use of the microbial biomass, Novacq™, in L. vannamei feeds. This study investigated the effects of supplementing Novacq™ at 100 g kg−1 in practical and commercial feeds in postlarvae 12 (PL 12) and juvenile white leg shrimp. Three experiments were carried out. In Experiment 1, PL12 were fed for 21 days with a Control, Novacq™ or Commercial feed. The Novacq feed was equal in PL12 performance to the Commercial diet and superior to the Control (final individual weight = 0.169, 0.167 and 0.087 g; percentage weight gain = 8014, 7956 and 4091% for Novacq™, Commercial and Control feeds, respectively). No statistical differences in survival, coefficient of variation and daily feed offered were observed across dietary treatments. In Experiments 2 and 3 the performance of juvenile shrimp fed practical and Commercial feeds supplemented with Novacq™ for 42 days, respectively. In Experiment 2, Novacq™ feed outperformed the Control feed by improving survival (89 vs. 51%), final individual weight (7.4 vs. 3.5 g), weight gain (7.1 vs. 3.2 g), and percentage weight gain (1997 vs. 898%). In Experiment 3 supplementing Novacq™ into the Commercial feed improved performance (final individual weight = 6.4 vs. 5.5 g, weight gain = 6.0 vs. 5.1 g, and percentage weight gain = 1712 vs 1443%) and reduced the coefficient of variation (19 vs 53%). Shrimp fed feeds containing Novacq™ also displayed numerically reduced daily feed offered and estimated feed conversion ratio values in comparison to the other dietary treatments. Whole-body composition was similar across dietary treatments. In summary, supplementation of Novacq™ in practical and Commercial feeds improved growth and efficiency of PL12 and juvenile shrimp suggesting its validity as a useful feed additive in the nutrition of white leg shrimp.

Fish culture technology using double net system for hybrid grouper (brown marbled grouper Epinephelus fuscoguttatus × giant grouper Epinephelus lanceolatus) and rabbitfish (Siganus canaliculatus)

Fish culture technology using double net system based on trophic level predicted can improve productivity. The aim of this research was to evaluate a fish culture technology of grouper and rabbitfish using double net system based on trophic level. This research was conducted with different stocking density. The net used was double net system. The Outer net HDPE with four cage with size of 4 × 4 × 4 m/cage and inner net HDPE with size of 3 × 3 × 3 m/cage. Inner net cage was stocked 20 grouper fish/m3 while outer net was stocked with different density of rabbit fish, 6 fish and 12 fish/m3. Each treatment was duplicated. The result showed the hybrid grouper production up to 205 kg with an individual final weight of 743 g while production of rabbit fish with stocking density 6 and 12 fish/m3 consequently was 10 kg with an individual final weight of 143 g and 15 kg with an individual final weight of 148 g. N and P content in hybrid grouper meat from feed consumed were 25% total N and 11 % total P, however 52 % of N and 74 % of P were released as faeces and excretion to the water. Rabbitfish with stocking density of 12 fish/m3 was the most effective production using double net system.

Reevaluating Polyunsaturated Fatty Acid Essentiality in Rainbow Trout

AbstractThe National Research Council (NRC) reports that the essential fatty acid requirements of Rainbow Trout Oncorhynchus mykiss can be satisfied by 0.7–1.0% 18:3(n‐3) or 0.4–0.5% n‐3 long‐chain (LC) polyunsaturated fatty acids (PUFAs; defined by NRC as 20:5[n‐3] + 22:6[n‐3]) in the diet. These requirements were defined roughly 50 years ago and do not consider the importance of n‐6 PUFAs in the diet. Therefore, we assessed survival, growth performance, and tissue fatty acid composition of juvenile Rainbow Trout (mean initial weight ± SE = 24.6 ± 0.1 g; 10 fish/tank, 4 tanks/diet) that were fed experimental diets (53% protein; 13% lipid) containing fish oil, fully hydrogenated soybean oil, or fully hydrogenated soybean oil with five different combinations of fatty acid ethyl esters (18:2[n‐6], 18:3[n‐3], 20:4[n‐6], 20:5[n‐3], and 22:6[n‐3]) to illuminate the relative essentiality of n‐3 and n‐6 PUFAs. Final individual weight (78.2–132 g), weight gain (216–433%), feed conversion ratio (0.93–1.42), specific growth rate (2.05–2.98% body weight/d), and hepatosomatic index (1.4–2.1) were significantly affected by dietary treatment whereby Rainbow Trout that received the fish oil‐based diet outperformed all other treatments. Growth of fish that were given different combinations of fatty acid ethyl esters was not statistically different. Fatty acid tissue composition generally reflected dietary treatment, with the greatest profile changes observed in intraperitoneal fat, fillet, and liver and the smallest changes occurring in brain and eye tissues. Results largely validate previous reports indicating that Rainbow Trout are physiologically able to synthesize LC‐PUFAs from C18 PUFAs and therefore do not necessarily require LC‐PUFA‐rich feeds. However, numeric increases in the growth of Rainbow Trout suggest that this species achieves an energetic advantage if offered n‐3 and n‐6 LC‐PUFAs in the diet.

Feeding Regime Has Little Impact on Weight Loss of Hybrid Crappies Pomoxis spp. and Redear Sunfish at a Low (Winter) Water Temperature when Fed a Noncommercial Diet of Blood Worms

AbstractWinter mortality is a problem for fish producers in temperate regions of the USA, including Arkansas. Hybrid crappies (Black Crappie Pomoxis nigromaculatus × White Crappie P. annularis) and Redear Sunfish Lepomis microlophus are popular among recreational anglers. Methods of winter feeding vary widely among existing commercial farms. The impact of different winter feeding regimes on performance of hybrid crappies and Redear Sunfish was evaluated in temperature‐controlled aquarium systems. Juvenile hybrid crappies and Redear Sunfish were cultured at approximately 9°C to mimic winter conditions. Three feeding regimes were implemented (3 tanks/regime) in which an ad libitum ration of blood worms was administered twice per week, once per week, or once per month. After 13 weeks of culture, there were no observed differences in weight loss, survival, specific growth rate, or final individual weight for either hybrid crappies or Redear Sunfish. Hybrid crappies lost 27–29% of their initial body weight, while Redear Sunfish lost more than 30% of their initial body weight. Fatty acid composition of both species differed significantly among feeding treatments, showing a decline in saturated fatty acids from initial levels and increases in or static levels of highly unsaturated fatty acids. Results suggest that feeding regime has little effect on weight gain in hybrid crappies and Redear Sunfish when fed at a colder water temperature.

Effects of supplemental LED lighting on water quality and Pacific white shrimp (Litopenaeus vannamei) performance in intensive recirculating systems

Indoor shrimp production systems allow production of fresh shrimp year-round near specific markets. However, there is typically little to no natural light available, and it is unclear whether artificial lighting may benefit systems. This study examined the effects of supplemental light-emitting diode (LED) lighting, designed for plant growth, on shrimp (Litopenaeus vannamei) production, water quality, and nutritional dynamics in intensive indoor shrimp systems. Four 1-m3 round tanks with settling chambers and external biofilters were assigned to one of three treatments. One treatment received 24 h of lighting per day (Full Light, FL), another had 12 h of lighting (Partial Light, PL), and the third treatment had no supplemental lighting provided (No Extra Light, NL). All tanks were stocked with 250 shrimp with an average initial weight of 1.2 g and were harvested after 84 days. Shrimp FCR was significantly lower and total biomass was significantly higher in the FL treatment compared with PL and NL treatments. Growth rate and final individual weight were significantly greater in FL and PL treatments, and survival was significantly higher in the FL treatment than the PL treatment. Turbidity, suspended solids, and nitrate concentration were significantly lower in the FL treatment versus PL and NL treatments. Shrimp in the FL and PL treatments contained significantly higher concentrations of n-6 fatty acids and lower docosahexaenoic acid than NL shrimp. The results of this study indicate that supplemental lighting in intensive indoor shrimp systems can improve shrimp production and have effects on biofloc and shrimp nutritional characteristics.

Ảnh hưởng của CO2 lên tỉ lệ sống, tăng trưởng, enzyme tiêu hóa và glucose của tôm thẻ chân trắng (Litopenaeus vannamei Boone, 1931) giai đoạn tôm bột đến tôm giống

This study was carried out to determine the effects of CO2 on survival, growth, digestive enzyme activity and glucose concentration of white leg shrimp from 15-day postlarvae to juvenile stage. The study was designed using a completely randomized with 4-CO2 treatments including 2.32, 7.81, 19.0 and 45.6 mg/L equal to pH of 8.1, 7.6, 7.2 and 6.8, respectively. Postlarvae of 0.019 g and 1.20 cm length were stocked at the density of 100 ind./200-L tank. After 45 days, the survival rate of shrimp in control treatment (2.32 mg/L CO2 or pH=8.1) was 70.0%, and the lowest survival rate occurred in the CO2 treatment of 45.6 mg/L (28.3%). The lowest final individual weight and length in CO2 concentration of 45.6 mg/L were 1.09 g and 4.69 cm. The lowest enzyme activities were in CO2 treatment of 45.6 mg/L. Glucose concentration was highest in 37.5 mg/100 mL. The high CO2 concentration will adversely affect growth, survival rate, reduce some digestive enzymes and increase glucose concentration in hemolymph of white leg shrimp.

Evaluation of alternative pond production systems for raising largemouth bass, Micropterus salmoides

This study evaluated three different pond‐based production systems for raising largemouth bass, Micropterus salmoides, for the food fish market, using nine 0.04‐ha ponds. Treatments included traditional ponds (TP), intensively aerated ponds (IAP), and split‐pond systems (SPS). TP and SPS ponds were aerated at 9.3 kW/ha, while IAP was aerated at 18.6 kW/ha. TP was stocked at 7,500 fish per ha (three replicates per treatment), and the other two production systems (SPS, IAP) were stocked with 12,500 fish per ha. Feed‐habituated advanced fingerlings (128 ± 47.6 g mean individual weight) were cultured for 157 days. Fish were fed a formulated diet (42% protein, 16% lipid) four times a day, feeding with a maximum allowance of 3% of total body weight and readjusted to the initial body weight biweekly. Fish raised in the SPS displayed a significantly lower specific growth rate, lower individual final weight, and lower weight gain, but the biomass gained was significantly higher than TP but not IAP. Final biomass gained was 50% higher in the SPS and IAP than in the TP. Survival rate and feed conversion ratio were not significantly different among treatments and ranged from 71 to 79% and 1.64 to 2.14, respectively.

Role of micro and macronutrients enrich fertilizers on the growth performance of prawn (Macrobrachium rosenbergii), rohu (Labeo rohita) and mola (Amblypharyngodon mola) in a polyculture system

A six month’s experiment was carried out in earthen ponds to evaluate the effect of micro and macro nutrients on the growth performance of Prawn (Macrobrachium rosenbergii), Rohu (Labeo rohita) and Mola (Amblypharyngodon mola) in a polyculture system during July to December 2017. The trial was conducted into two different treatments and one control each with three replications. In treatment-1, macronutrients enrich fertilizers like urea, TSP and molasses-yeast mixture were applied at the rate of 2.45, 2.45, and 3.09 (g m-2 week-1), whereas in treatment-2 micronutrients composition mixer applied at the rate of 4.50 g m-2 week-1 while no micro and macronutrients were applied in control. The mean value of all water quality parameters showed no significant differences among control and two treatments when One-way ANOVA was performed except hardness. The average final mean individual weights of prawn, rohu and mola in control, treatment-1 and treatment-2 were 22.10, 24.35, and 24.70 g; 141.10, 190.60 and 182.20 g; 3.36, 3.67 and 3.73 g, respectively. The survival rates of various species namely prawn, rohu and mola in control, treatment-1 and treatment-2 were 73.33, 89.58 and 86.25%; 78.00, 74.00 and 74.00%; 10.67, 15.33 and 15.33%, respectively. There was no significant difference in the survival rates of prawn, rohu and mola among control and treatments. Production after six months of culture was 351.8, 461.5 and 445.3 kg ha-1 in control, treatment-1 and treatment-2, respectively which were significantly different at 5% level of significance.&#x0D; Int. J. Agril. Res. Innov. &amp; Tech. 8 (2): 47-53, December, 2018

Feed management and the use of automatic feeders in the pond production of Pacific white shrimp Litopenaeus vannamei

The purpose of this study was to examine the effects of using automatic feeding and acoustic feedback systems on the pond culture of Pacific white shrimp Litopenaeus vannamei. This trial was performed using 16, 0.1 ha ponds stocked at 38 shrimp/m2 and grown for 13 weeks. The treatments used were a standard feeding protocol (SFP) fed twice daily, a Timer treatment fed a 15% increase to the SFP offering feed 6 times per day (Timer 15), a timer treatment fed a 30% increase to the SFP offering feed 6 times per day (Timer 30), and the AQ1 acoustic feedback system that fed based on feeding activity (AQ1). At the conclusion of the pond production trial, final individual weights of the shrimp were significantly different for all treatments 19.74 g, 25.15 g, 27.52 g, and 32.04 g for the SFP, Timer 15, Timer 30, and AQ1 treatments respectively. The shrimp yield for the AQ1 treatment (7430 kg/ha) was also significantly higher than the SFP (4843 kg/ha) or Timer 15 (5629 kg/ha) treatments. The AQ1 treatment also produced a significantly higher value of shrimp ($65,587/ha) than the SFP ($32,982/ha) or the Timer 15 ($44,279/ha). No significant differences were seen in FCR (1.07–1.24) or survival (58.5–63.9%). The results of this and previous work, demonstrated that increasing the number of daily feedings from 2 to 6 can allow for a higher daily feeding rate, which translated into higher growth and production. Improvements of feed inputs using feedback technologies improved the production as the number of feedings and quantity of feed was increased, resulting in further improvements in production. The results of this study indicate that increasing the number of daily feedings in the pond production of shrimp has the potential to significantly increase growth and can reduce the labor requirements for feeding.

Growth Performance and Feed Utilization of Low-Cost Artificial Feeds for Juvenile Asian Horseshoe Crab Culture

ABSTRACT A feeding experiment was undertaken for 84 days to investigate the growth performance and the feed utilization of two horseshoe crab species from partial replacement of fish meal (FM) with blood meal (BM), meat and bone meal (MBM), and poultry by-product meal (PBM) in their diet. Triplicate groups of Tachypleus tridentatus or Carcinoscorpius rotundicauda were fed nine isonitrogenous (digestible protein 40%) and isoenergetic (digestible energy 14 MJ kg-1) diet treatments. For both species, the growth performance, that is, final individual body weight and thermal-unit growth coefficient (TGC), and feed utilization, that is, including feeding rate (FR) and feeding efficiency ratio, of the juveniles fed with PBM and MBM at 2:1 ratio were higher than those of juveniles fed with diets containing PBM and MBM at 1:1 ratio at the same FM replacement level. Final individual body weight, TGC, and FR of the two species fed with the 100% FM replacement diets were significantly lower than in other diet treatme...