Tilapia Feed Research Articles

Rice Bran Expressing a Shrimp Antimicrobial Peptide Confers Delayed Spoilage of Fish Feed and Resistance of Tilapia to Aeromonas hydrophila

Penaeidin is an antimicrobial peptide family found in penaeid shrimp. Penaeidin3 has a broad spectrum of antimicrobial activity and is most effective against certain bacterial species. In this study, the penaeidin3-2 gene was cloned from the Chinese shrimp, Fenneropenaeus chinensis. It was then transformed into rice plants using an Agrobacterium-mediated transformation system. The transformants were verified by polymerase chain reaction (PCR) sequencing and real-time polymerase chain reaction (RT-PCR) analysis. To evaluate the application of penaeidin3-2 expressed by rice plants in the feedstock industry and aquaculture practice, the transgenic rice bran was added to fish feed. The proliferation of microbes in the feed was significantly inhibited by the transgenic rice bran. Furthermore, the mortality of tilapias challenged with Aeromonas hydrophila was also significantly reduced when they were fed with the transgenic bran expressing penaeidin3-2. Their intestinal flora changed when the fish were fed with rice bran expressing the introduced gene for a relatively long period. Fish that survived the challenge had a more intact midgut structure. These results indicate that penaeidin3-2 expressed in rice plants may possess the ability to modulate the intestinal bacterial community and protect the gut structure from damage.

The Effects of Creatine Monohydrate and Conjugated Linoleic Acid on Growth Performance and Fiber Type, Fiber-related Genes and Metabolic Enzymes in the Tilapia Muscle

We analyzed the effects of creatine monohydrate (CMH) and conjugated linoleic acid (CLA) on muscle fiber type, related genes, metabolic enzymes, and growth performance in tilapia (Oreochromis mossambicus). The addition of CMH and CLA in the basal feed significantly reduced the daily intake of tilapia, indicating that CMH and CLA had positive effects on improving the tilapia feed conversion rate. CMH up-regulated the relative mRNA expressions of MyHC I, IIa/IIb in the tilapia muscle. The activities of oxidases (SDH, MDH), AMPK, and the mRNA expression levels of PGC-1α, MEF2C, and GLUT4 were increased but those of MyHC IIx and LDH activity were decreased. CLA increased the proportion of oxidative muscle fibers in tilapia muscle while enhancing the activities of MDH, SDH, and AMPK and increasing mRNA expressions of PGC-1α and GLUT4. However, it decreased the proportion of glycolytic muscle fiber types and LDH activity. CMH and CLA could activate the AMPK activity in the muscle, further up-regulating the gene expression in the AMPK pathway, enhancing oxidative metabolic ability, and transforming the muscle fiber type. The study provides a strategy for improving the quality of future tilapia culture by regulating muscle fiber type transformation through CMH and CLA supplementation.

In situ growth and photosynthetic activity of Cyanobacteria and phytoplankton dynamics after passage through the gut of silver carp (Hypophthalmichthys molitrix), bighead carp (Aristichthys nobilis), and Nile tilapia (Oreochromis niloticus)

The growth and photosynthetic activities of Cyanobacteria passed through the gut of silver carp (Hypophthalmichthys molitrix), bighead carp (Aristichthys nobilis), and tilapia (Oreochromis niloticus) were compared with those of phytoplankton taken directly from Lake Taihu during a 13-day in situ dialysis culture. After the first 3–5 days of reduced activity after excretion by silver carp and bighead carp, the photosynthetic activity of Cyanobacteria recovered and rose significantly higher (P < 0.01) than levels in the control population, whereas there was a notable reduction of photosynthetic activity after passage through tilapia gut. The phytoplankton biomass showed a 2- to 3-fold increase of growth, and extracellular polysaccharide production was also stimulated after passage through silver carp and bighead carp gut. Chlorophyta fluorescence was detected at much higher levels than that of Cyanobacteria and Bacillariophyta after passage through tilapia gut. Scenedesmus obliqnus and Chlamydomonas sp. contributed much to the growth of the Chlorophyta during the in situ cultivation. However, the total phytoplankton biomass showed a distinct reduction in the tilapia treatment during the culture. The study indicated that Nile tilapia feeding and defecation may help remove Cyanobacteria from the water column and favor a community shift to Chlorophyta.

Pengukuran Kecernaan Lemak Kasar, Bahan Organik dan Energi pada Pakan Ikan Nila (Oreochromis niloticus) dengan Menggunakan Teknik Pembedahan &lt;br&gt;&lt;i&gt;[Measurements Of Extract Ether Digestibility, Organic Matter and Energy Feed In Tilapia (Oreochromis niloticus) Using Surgery Techniques]&lt;I&gt;

Abstract Tilapia is a freshwater fish species are widely cultivated in Indonesia. Tilapia production continues to grow every year, the average increase in the number of experienced production tilapia reaches 22.24% in the 2010-2011 range. Tilapia production in 2011 reached 567.449 tons and was second aquaculture production by major commodity after seaweed. This study aimed to determining differences in extract ether digestibility, organic matter, and energy on feed derived from different factories in tilapia (Oreochromis niloticus) using surgery techniques. The research design is using completely randomized design. The variables were measured extract ether digestibility, organic matter, and energy in tilapia feed. Analysis of the data processed using Analysis of Variance (ANOVA) to determine differences in treatment given. If there is a difference then followed by Duncan's Multiple Range Test with a significance level of 5%. Based on the findings that there were no significant differences (p&gt;0.05) in extract ether , organic matter, and energy digestibility of the feed value of tilapia. The results stated that the feed treatments A, B and C efficiently digested by tilapia.

Composición del mercado nacional de alimentos balanceados para tilapia de Costa Rica.

The source and themanufacturing process of tilapia feed sold in the country andregistered in the Quality Control Program for Animal Feed ofthe Ministry of Agriculture and Livestock of Costa Rica andthe prescriptions according to the physiological stage, chemicalcompositions and the relations crude protein : metabolizableenergy and calcium : phosphorus, were evaluated andcompared to nutritional requirements. The physical qualitywas evaluated in terms of particle size of the pellets againstthe size of fish. The market study compared the selling priceper nutrient unit in each formula, with respect to its contents.It was determined that 82.35% of the formulas were manufacturedin Costa Rica, 82.23% were extruded feed and 41%of the formulas are recommended for all types of tilapia fish,which resulted in inconsistencies with respect to the requirements.However, all crude protein levels in different fingerlingsformulas complied with requirements. With respect tophysical quality the situation is more critical, since only23.53% of the registers indicated the size of the pellet. Only5 out of the 17 registered formulas are being marketed, reasonenough to conclude that comparing formulas on their sellingprice per nutrient unit, is not a good criteria for selectinga particular formula.

Nutrient load estimation in the waste of Nile tilapiaOreochromis niloticus(L.) reared in cages in tropical climate conditions

We sought to estimate the nutrient load in the waste released into aquatic environments based on the feeding of Nile tilapia (Oreochromis niloticus, L.) reared in cages that were installed in artificial reservoirs. For the calculation, an analysis of the chemical composition of commercial feeds intended for this species in their various stages of production was conducted (N = 130). We combined this information with a meta-analysis of published data from commercial producers in Brazil about expected feed intake, feed conversion and other animal production indices, and body composition. With these data, it was possible to estimate the load. We estimated that 18% of the feed given to the animals is not consumed and is lost in the aquatic environment. The calculated average digestibility was 71.97% for the organic matter in the diet, 84.06% for protein and 54.40% for phosphorus. The estimated nutrient deposition efficiency, with respect to what was actually consumed by the tilapia, was 26.39% for organic matter, 43.25% for protein and 34.07% for phosphorus. The total nutrient load in the waste per tonne of biomass of produced tilapias was estimated to be 1040.63 kg of organic matter, 44.95 kg of nitrogen and 14.26 kg of phosphorus, representing 78%, 65% and 72% of the respective nutrient amounts supplied by the feed. The information obtained in this study serves as a reference for predicting the potential impact of tilapia farming in reservoirs and to establish scientific parameters for the planning of this activity.

Determination of aflatoxin and fumonisin levels through ELISA and HPLC, on tilapia feed in Nayarit, Mexico

A survey of fungal contamination and presence of aflatoxins (AFs) and fumonisins (FBs) in 30 feed samples collected from 10 tilapia farms during three seasons in Nayarit State, located in north-western Mexico, was carried out using ELISA as screening and High-Performance Liquid Chromatography (HPLC) as confirmatory method. Mycobiota included Aspergillus flavus and Fusarium spp. AFs were detected in 63.3% of samples using ELISA, but confirmation by HPLC revealed that all samples were under the detection limit. Regarding to FBs, positive samples were detected using both methods, with 19 positive samples (60% of total) by ELISA and 14 positive samples (46.6% of total) by HPLC and levels ranging from 0.148 to 2.587 mg/kg. Correlation was observed between both methods (r = 0.516, p = 0.004) for FBs results. No sample exceeded the European maximum levels for any of the mycotoxins. Water activity of samples ranged from 0.345 to 0.655, suggesting that mycotoxin occurrence is probably related to raw material contamination.

Production Economics of Nile Tilapia (Oreochromis niloticus) Pond Culture in El-Fayum Governorate, Egypt

Econometric techniques were used to estimate a production function for tilapia pond culture in El-Fayum Governorate, Egypt, utilizing cross-sectional field data. Explanatory variables were feed, initial stocking weight, and pond size. The function was used to examine returns to scale, estimate the productivity of feed and initial stocking weight, and estimate the profit maximizing demand equations for feed and fingerlings. Diminishing returns to scale seem to exist for tilapia pond culture. Optimal economic stocking and feeding rates, yield, and profits for the whole sample were estimated at prevailing prices. Results indicated that producers were using stocking rates greater than the optimal by 36% to 115% and using insufficient feed by 8% to 22%. Investigation of the effects of changes in tilapia selling price and feed price on optimal stocking and feeding rates, yield, and profits showed that a change in tilapia selling price has greater effect on profits, yield, stocking, and feeding rates than a proportional change in feed price. Profits, feeding, and stocking rates are more sensitive than yield to changes in selling price, while feeding rate is more sensitive than stocking rate, yield, and profits to changes in feed price.

Influencia da farinha de manga no crescimento e composição corporal da tilápia do Nilo

Mango meal with peel was evaluated as carbohydrate source in substitution of corn, for tilapia juvenile growth and carcass composition. There were used 180 fish (4,69 ± 0,06 g) in 12 tanks of 500 L, fed three times a day (6 % of live weight), in a water recirculating system with biofilter. Four diets were evaluated with different mango meal concentrations T1= diet with 30 % of corn; and T2, T3 and T4 in which 33, 66, and 100 % of corn was replaced by mango meal. All of the treatments had three repetitions. At the end of 45 days performance was evaluated (final weight, weight gain; specific growth rate, feed consumption, apparent feed conversion rate, carcass yield, survival) and chemical carcass composition. The levels of mango meal substitution by corn meal affected all the variables analyzed from level 33 % (p 0,05). Carcass chemical composition values were changed except for ash. Mango meal in substitution for corn may be used until the level of 33 % in Nile tilapia feed without damage for growth performance and carcass chemical composition.

Effects of Steam, Moisture, and Screw Speed on Physical Properties of DDGS‐Based Extrudates

ABSTRACTA fractional factorial design with a replicated central composite point was used to investigate the effects of extrusion processing on physical properties of distillers dried grains with solubles (DDGS) based aquafeeds using a twin‐screw extruder. Extrusion cooking trials were performed with a nutritionally balanced ingredient blend for Nile tilapia, with two levels of screw speed (350 and 450 rpm), two levels of extruder water (0.236 and 0.302 kg/min), and two levels of conditioner steam (0.1 and 0.15 kg/min). The central point was 400 rpm screw speed, 0.271 kg/min extruder water, and 0.12 kg/min conditioner steam. Effects of these processing conditions on extrudate characteristics were extensively analyzed and included moisture content, water activity, thermal properties, expansion ratio, unit density, bulk density, color, water stability, sinking velocity, water absorption and solubility indices, and pellet durability index. Increasing the extruder water and conditioner steam resulted in a 5.3% decrease and nearly 8.6% rise in mass flow rate, respectively. As screw speed increased from 350 to 400 rpm, water stability and water activity increased by 13 and 58%, respectively. Increasing extruder water from 0.236 to 0.302 kg/min led to a significant increase in water stability by 12.5% and decreases in water absorption index, water activity, and expansion ratio by 13, 21, and 5.5%, respectively. As conditioner steam increased from 0.1 to 0.15 kg/min, sinking velocity and water absorption index decreased by 25 and 15%, respectively. Increasing conditioner steam from 0.1 to 0.12 kg/min resulted in 20, 5.5, 10, and 3% decreases in moisture content of the extrudates, brightness (L*), water stability, and expansion ratio, respectively. It also increased bulk density by 5.8% and unit density by 4.2%. Overall, all trials produced viable extrudates with properties appropriate for Nile tilapia feeding.

Formulation of Cost Effective Grow out Feeds for Macrobrachium rosenbergii Culture in Fiji

The change from traditional subsistence to semi-intensive is leading to an increase in the demand for aquaculture feeds. The culture of freshwater prawn, Macrobrachium rosenbergii in Fiji as protein source and source of income for small-scale farmers is important. However, due to the unavailability and high cost of feed ingredients and formulated feeds, the supply and quality of feeds for aquaculture development is restricted. In addition, the lack of information on cost–effective channels to deliver feeds to farmers has contributed to the poor production and profitability. A nutritional study was conducted to evaluate growth performance of M. rosenbergii fed iso-energetic, low cost formulated diets, using locally available ingredients in ponds for 124 days. Two formulated (MBM+MM+CP-diet 1 and FM+Wht-diet 2) and two commercial (Crest tilapia pellet-diet 3 and Pacific prawn pellet - diet 4) diets were fed. The study indicated no significant differences for weight gain and survival rate (P ≥ 0.05). It was observed that diet 2 induced highest growth rate while the lowest FCR (0.97 ± 0.02) value was obtained for the same diet. The survival of prawns ranged between 83.43 mm ± 5.55 and 89.26 mm ± 0.40%. The highest prawn production was obtained with diet 2 at 0.16 kg/m2. The economic analysis of M. rosenbergii production showed that diet 2 was the least expensive (FJ $0.53) to produce 1 kg of prawn as compared to the commercial diets (Pacific Prawn feed –FJ $0.89 and Crest Tilapia feed–FJ $0.69). Therefore, this study suggests that M. rosenbergii growth was slightly improved when using the formulated diet 2 although the highest survival rate (89.26 ± 0.40%) was obtained from the formulated diet 1. Diet 2 may be recommended to the farmers for monoculture of M. rosenbergii in ponds in comparison to both commercial diets in Fiji.

Formulation of Cost Effective Grow out Feeds for Macrobrachium rosenbergii Culture in Fiji

The change from traditional subsistence to semi-intensive is leading to an increase in the demand for aquaculture feeds. The culture of freshwater prawn, Macrobrachium rosenbergii in Fiji as protein source and source of income for small-scale farmers is important. However, due to the unavailability and high cost of feed ingredients and formulated feeds, the supply and quality of feeds for aquaculture development is restricted. In addition, the lack of information on cost-effective channels to deliver feeds to farmers has contributed to the poor production and profitability. A nutritional study was conducted to evaluate growth performance of M. rosenbergii fed iso-energetic, low cost formulated diets, using locally available ingredients in ponds for 124 days. Two formulated (MBM+MM+CP-diet 1 and FM+Wht-diet 2) and two commercial (Crest tilapia pellet-diet 3 and Pacific prawn pellet - diet 4) diets were fed. The study indicated no significant differences for weight gain and survival rate (P ≥ 0.05). It was observed that diet 2 induced highest growth rate while the lowest FCR (0.97 ± 0.02) value was obtained for the same diet. The survival of prawns ranged between 83.43 mm ± 5.55 and 89.26 mm ± 0.40%. The highest prawn production was obtained with diet 2 at 0.16 kg/m2. The economic analysis of M. rosenbergii production showed that diet 2 was the least expensive (FJ$0.53) to produce 1 kg of prawn as compared to the commercial diets (Pacific Prawn feed -FJ$0.89 and Crest Tilapia feed - FJ$0.69). Therefore, this study suggests that M. rosenbergii growth was slightly improved when using the formulated diet 2 although the highest survival rate (89.26 ± 0.40%) was obtained from the formulated diet 1. Diet 2 may be recommended to the farmers for monoculture of M. rosenbergii in ponds in comparison to both commercial diets in Fiji.

The effect of NovaSil dietary supplementation on the growth and health performance of Nile tilapia (Oreochromis niloticus) fed aflatoxin-B1 contaminated feed

The objective of this study was to evaluate the ability of NovaSil (NS) clay to sorb and mitigate the toxic effects of aflatoxin B1 (AFB1) in Nile tilapia (Oreochromis niloticus). Growth performance, targeted innate immunological function, intestinal microbial community and histology were evaluated after feeding tilapia diets with or without AFB1 and/or NS for 10weeks. Aflatoxin B1 at concentrations of 1.5 and 3.0ppm significantly (P<0.05) decreased weight gain, feed efficiency, hepatosomatic index and macrophage extracellular superoxide anion production in tilapia, regardless of NS addition to the diet. The overall results regarding the efficacy of NS were mixed; however, there was a trend (P=0.157) towards AFB1-toxicity prevention in regards to macrophage extracellular superoxide anion production. Additionally, when 0.5 and 1% NS was included in diets containing 1.5ppm AFB1, total histopathological score was lowered; however, this protective effect was not evident when fish were exposed to 3.0ppm AFB1. Denaturing gradient gel electrophoresis was performed to assess the effects of both AFB1 and NS on gut microbiota, but no significant differences were found among treatment groups.

Effect of Sophora flavescens on non-specific immune response of tilapia (GIFT Oreochromis niloticus) and disease resistance against Streptococcus agalactiae

The paper describes the effect of a diet supplemented with the Chinese traditional herbal medicine Sophora flavescens on the immunity and disease resistance of an Oreochromis niloticus GIFT strain. Experimental diets containing 0.025%, 0.050%, 0.100%, 0.200%, and 0.400% S. flavescens, as well as a control group without S. flavescens were used. We tested the non-specific humoral immune responses (lysozyme, antiprotease, and complement) and cellular immune responses (reactive oxygen species and nitrogen species production and myeloperoxidase), as well as disease resistance against Streptococcus agalactiae. S. flavescens supplementation at all dose significantly enhanced serum lysozyme, antiprotease, and natural hemolytic complement activity. Similarly, all S. flavescens doses enhanced cellular myeloperoxidase activity. The increased production of reactive oxygen species and reactive nitrogen intermediates by peripheral blood leucocytes was observed in most of the treatment groups throughout the test period. The fish fed 0.100% S. flavescens had a percent mortality of 21.1% and a relative percent survival of 73.3% compared with the group fed the basal diet during the S. agalactiae challenge. The results suggest that S. flavescens can be recommended as a tilapia feed supplement to enhance fish immunity and disease resistance against S. agalactiae.

Introduction of modern endocrine techniques for the production of monosex population of fishes

Of the techniques available to mass-produce a sterile or monosex population, the hormonal induction of sex reversal is the most widely practiced. This paper presents the synthesis of works done on sex reversal using 17α methyltestosterone (17αMT), 17β estradiol, non-steroidal aromatase inhibitors (AIs) and oestrogen receptor agonist, tamoxifen in commercially important aquaculture species mossambique tilapia Oreochromis mossambicus, Nile tilapia Oreochromis niloticus, common carp Cyprinus carpio, mahseer Tor putitora and African catfish Clarias gariepinus. Results on sex reversal for producing female T. putitora delineated that treatment to fry of T. putitora 60days post fertilization (60dpf) with 17β estradiol (150mg/kg feed) fetched 69.5% female population. Further, raised temperature (23±1°C) five degrees above ambient temperature brought about 37.5% female populations which was above the control (24.4% females). Feeding tilapia O. mossambicus fry after yolk sac absorption stage (8dpf) with 17αMT incorporated diet (35mg/kg feed) under long photoperiod (16L:8D) for 60days obtained 100% sex reversed males with excellent growth. Treatment with tamoxifen and letrozole (200mg/kg feed) to fingerlings of C. carpio and O. niloticus for 60days brought about 82.5% and 98.5% masculinization with increased level of testosterone (T). Letrozole treatments to C. gariepinus significantly (p<0.001) increased T level to 1197.76±18.79pg/ml when treatment was given through feed for 60days and 1470.5±20.76pg/ml via intraperitoneal injection. There was significant deviation in sex ratio leading to high level of masculinization in different aquaculture species with treatments of hormones and AIs.

Alga marinha marrom para alevinos de tilápia do nilo

Este trabalho avaliou os efeitos de níveis crescentes da farinha de alga marrom Ascophyllum nodosum (FAM) nas rações para alevinos de tilápia do Nilo Oreochromis niloticus. O experimento, com delineamento inteiramente casua-lizado, durou 42 dias. Foram utilizados alevinos de tilápia do Nilo (n= 75) com idade média de 30 dias e peso médio de 0,43 ± 0,02 g, distribuídos em 25 tanques plásticos submetidos à cinco tratamentos e cinco repetições. Os tratamentos foram níveis crescentes de farinha de alga marrom (5, 10, 15 e 20 g kg-1 de ração) e uma ração controle (sem FAM). Cada unidade experimental foi composta por um tanque plástico de 36 L com três alevinos. Foram estudados os parâmetros médios de peso final, percentagem de ganho de peso, taxa de conversão alimentar aparente, comprimento total e rendimento de carcaça, com e sem cabeça. As médias de peso final, percentagem de ganho de peso e comprimento total não foram influenciadas pelos tratamentos (p&gt;0,05). Os valores da taxa de conversão alimentar aparente melhoraram linearmente (p

Use of Diet Crossover to Determine the Effects of β‐glucan Supplementation on Immunity and Growth of Nile Tilapia, Oreochromis niloticus

Juvenile Nile tilapia were fed either a basal (control) diet (n = 6 aquaria) or a diet supplemented with 1 g/kg β‐glucan (n = 24 aquaria) for 4 wk. At the end of this period, fish receiving β‐glucan were continued on the same diet (n = 12 aquaria) or switched to the control diet (n = 12 aquaria) for 2 wk. After 6 wk, tilapia continuously fed the β‐glucan supplemented diets had improved weight gain and feed efficiency than those fed the control diet uninterrupted or switched from the β‐glucan diet to the control after 4 wk. Feeding tilapia β‐glucan for 4 wk and then switching to the basal diet for 2 wk caused a significant increase in the respiratory burst of polymorphonuclear lymphocytes (17.77 × 103 units/1000 white blood cells [WBC]) compared to catfish fed the control diet (13.50 × 103 units/1000 WBC) or the β‐glucan diet continuously (13.57 × 103 units/1000 WBC), but other immune parameters were unaffected. Tilapia were then challenged with Streptococcus iniae. The two groups were divided again (n = 6 aquaria) postchallenge and continued on the same diet or switched to the other diet (β‐glucan or control) for another 3 wk. No differences in survival to S. iniae infection occurred between dietary groups.

Apparent and true digestibility of protein and amino acid in feedstuffs used in Nile Tilapia feed as determined by the technique of dissection

The objective of this study was to determine the coefficients of apparent and true digestibility of protein and amino acids of five feedstuffs (corn, wheat bran, soybean meal, corn gluten meal and fish meal) in 900 sex-reversed Nile tilapia (Oreochromis niloticus) of the Thai strain during the growth phase, with an initial weight of 315±8.45 g. A total of 750 fish were distributed according to a randomized block design (repetitions in time) into five treatments with six replicates of 25 fish each. The remaining 150 fish were fed a protein-free diet to measure endogenous protein and amino acid losses in order to determine the true digestibility of these components. Each tested diet contained a single protein source, which consisted of one of the evaluated feedstuffs. Digestibility was indirectly estimated using chromic oxide at 0.50% as marker. Digesta was collected from the last 5 cm of the distal intestine (between the ileal-rectal valve and the anus) using the dissection technique. Apparent digestibility coefficients of protein and amino acids were, on average, 74.69 and 73.62% for corn, 73.74 and 72.81% for wheat bran, 86.01 and 84.66% for soybean meal, 85.19 and 84.29% for corn gluten meal, 76.74 and 75.56% for fish meal, respectively. True digestibility coefficients of protein and amino acids were, on average, 85.21 and 83.97% for corn, 84.41 and 83.74% for wheat bran, 87.22 and 87.51% for soybean meal, 87.97 and 87.34% for corn gluten meal, and finally 79.58 and 78.44% for fish meal, respectively.

Effects of Dietary Yeast (Saccharomyces cerevisia) Supplementation in Practical Diets of Tilapia (Oreochromis niloticus).

Simple SummaryWorld communities are concerned about the increasing impact of the aquaculture activities on fisheries resources. Aquaculture sector uses 2–5 times more fishmeal to feed farmed species than what is supplied by the farmed product. Therefore, the reduction of fishmeal dependency may provide more economic and environmentally friendly aquaculture. By identifying alternative protein sources, the authors find that brewer’s yeast is a suitable raw material as fishmeal replacement in feed of tilapia. The 15% inclusion may promote growth without affecting the end-product quality. A 51-day feeding trial was carried out to determine the effects of various dietary levels of brewer’s yeast, Saccharomyces cerevisiae, in the growth performance, body composition and nutrient utilization in Nile tilapia, Oreochromis niloticus, juveniles. Fish (7.6 ± 0.3 g) were stocked into eighteen 1,000-L tanks (100 fish per tank; n = 3) and fed to apparent satiation six isonitrogenous (27% crude protein) and isoenergetic (19 kJ/g) diets, formulated to contain different dried yeast levels (0%, 10%, 15%, 20%, 30% or 40% diet) in substitution to fishmeal. Body weight tripled at the end of the feeding trial for fish fed up to 20% dietary yeast incorporation. Daily growth coefficient (DGC, % body weight/day) decreased with increasing dietary yeast level (P < 0.0001). Voluntary feed intake (VFI, %BW/day) did not vary significantly with increasing yeast level. Fish fed 40% yeast showed significant reduction in protein efficiency rate, protein retention and nitrogen gain. Increasing levels of dietary yeast did not significantly affect protein or lipid digestibility. Dietary dried yeast was seemingly palatable to tilapia juveniles and was suitable up to 15% inclusion to promote growth and efficient diet utilization, without affecting body composition.

Aquatic Weed as Potential Feed for Mozambique tilapia, Oreochromis mossambicus

A study was conducted to evaluate the nutritional potentials of three commonly available aquatic weeds namely, lemna (Lemna minor), water hyacinth (Eichhornia crassipes) and azolla (Azolla pinnata) for ascertaining their suitability in fish feed with the aim of reducing the cost of traditional feeds. Three isonitrogenous (30% crude protein approximately) and isocaloric (4.0 kcal g−1 approximately) diets were formulated including lemna, water hyacinth and azolla as principal ingredient. Three groups of juvenile tilapia fish (Oreochromis mossambicus) of thirty (30) number per group (Average weight 5.1 ± 0.15 g; length 4.5 ± 0.12 cm) were fed with three different types of feeds with lemna meal (LNM), water hyacinth meal (WHM) and azolla meal (AZM) for 90 days duration. Body weight gain, feed conversion ratio (FCR), protein efficiency ratio (PER) and gonadosomatic index (GSI) were significantly (P<0.05) high in LNM fed fish in comparison to the others. The lemna possibly contains superior quality of protein which in turn influenced growth, growth parameters and fecundity of cultured fish.