Live Food Enrichment Research Articles

The Effects of Plant Protein-Enriched Live Food on Larval Zebrafish Growth and the Status of Its Digestive Tract Development.

Live food is necessary for the proper development of zebrafish larvae, providing nutrition in a form that is easily digestible and available to the larvae. Live food is commonly enriched to increase the dietary content of certain nutrients. However, little research has been done on protein-based enrichments, especially those of plant origin. This study sought to examine how different quality protein enrichments affected the composition of live food as well as growth and digestive tract development of larval zebrafish, Danio rerio. Larval zebrafish were fed from 3 to 22 days posthatch (dph) with one of six live food (rotifers Brachionus plicatilis and Artemia spp.) treatments: (1) live food with no enrichment (starved; control); (2) live food enriched with commercially used Spirulina spp. algae; (3) live food enriched with soybean meal (SBM); (4) live feed enriched with soy protein concentrate (SPC); (5) live feed enriched with a fishmeal hydrolysate; and (6) live feed enriched with intact fishmeal (FM). Proximate composition of live food was significantly affected by enrichment, in particular, protein content of rotifers was significantly increased by enrichment with SBM. Zebrafish fed SBM-enriched live food showed longer total body length than all other groups, except SPC. Zebrafish in the SBM group also showed increased gene expression of chymotrypsin in the intestine, possibly indicating improved intestinal development and extracellular digestion, which likely contributed to improved growth. Conversely, zebrafish fed hydrolysate-enriched live food showed reduced gene expression of alkaline phosphatase, possibly indicating a less developed intestinal tract, correlating with reduced growth compared to SBM group. Overall, plant protein was shown to be a promising source of live food enrichment for improving larval zebrafish growth.

Effectsofapplyingnutritional programming at different early stages of Largemouth bass (Micropterus salmoides, Lacepède) development on growth and dietary plant protein utilization.

Plant protein (PP) utilization in fish is limited due to lower digestibility compared to fishmeal (FM) and the presence of antinutritional factors. Its utilization can be improved by nutritional programming (NP), a method wherein a fish is provided a nutritional stimulus early in life which can alter their physiology. NPhas been shown to be effective but methods of applying NP are varied and have been applied at different stages of development with different outcomes. To find the optimal timeframe to perform NP in fish early stages Largemouth bass (Micropterus salmoides, Lacepède) were nutritionally programmed at three different ages in early development. In this study bass were programmed with: (1) live food enriched with soybean meal (SBM) from 6 to15days post-hatch (dph) (NPL), (2) SBM-based formulated diet from 16 to 25 dph (NPD1)and (3) formulated SBM-diet from 26 to35 dph (NPD2). After programming, each group was fed FM-diet before being refed SBM-diet from 100 to 172 dph. A positive control (PC) was fed FM-diet throughout. Final average body weight of PC was significantly higher than NPD1 and NPD2 but did not significantly differ from NPL. Overall NPL showed much improved growth and utilization of PP compared to NPD1 and was similar to growth achieved by PC. This study showed an optimum window of time exists wherein NP of Largemouth bass yields the best impact on growth in the larval stage and later in life when fed SBM-diet. Programming should be performed right after mouth opening using enriched live food and can result in growth similar to non-programmed fish fed FM-based diet. Programming effects similar to that of the live food approach can be achieved with formulated diet, however it is crucial that Largemouth bass are of a proper age and sufficiently developed when programmed with dry food or severe impacts on growth can occur.

Development of enriched Artemia and Moina in larviculture of fish and crustaceans: a review

Inconsistencies in the nutritional values of live food such as Artemia and Moina are well-known issues. The enrichment of live food is necessary to obtain the optimum nutrients needed for the growth, survival, and immune competence of fish and crustaceans' larvae. The enhanced growth and survival of fish and crustaceans' larvae are vital to continuous aquaculture production. However, enriched live food could be species-specific as various aquatic larval species may respond differently to the enrichment diets. The enrichment of Artemia and Moina as the "bags of nutrients" has been widely studied and involved various enrichment diets such as commercial diets containing essential fatty acids, highly unsaturated fatty acids, and vitamin C. The use of natural enrichment diets such as yeast, microalgae, and herbal extract, including the common name Chinese chaste tree leaf (Vitex negundo), is becoming popular in aquaculture nutritional development. These natural enrichment diets are more economical and environmentally friendly than commercial diets. The compositions of Artemia and Moina are both affected by the enrichment diets that they consumed, hence directly affecting the growth of the larvae that fed on them. Hence, this review highlights the development of enriched Artemia and Moina and their effects on the growth performance and the immune competence of fish and crustaceans' larvae.

Effects of feeding differentially enriched Artemia nauplii on the survival, growth, fatty acid composition, and air exposure stress response of Pacific cod (Gadus macrocephalus) larvae

The ability of enriched live food, such as Artemia, to improve the growth performance of Pacific cod (Gadus macrocephalus) larvae during larviculture has yet to be fully established. Thus, the effects of feeding differentially enriched Artemia to Pacific cod larvae were investigated here, specifically the effects on the survival, growth, fatty acid composition, and air exposure stress response of the larvae. Three different commercial Artemia enrichment emulsion oils were used: commercially available enrichment 1, 2, and 3, referred to as ER1, ER2, and ER3, respectively. Although ER2-treated Artemia contained the most eicosapentaenoic acid (EPA) and ER3-treated Artemia contained the most docosahexaenoic acid (DHA) and highly unsaturated fatty acid (HUFA), the ER1 enrichment improved overall survival, growth, and survival after air stress test to the greatest extent in larval Pacific cod. Furthermore, the levels of DHA and HUFA observed in larvae fed the ER1 diet were higher than the respective concentrations of these nutrients observed in larvae fed the other diets. Thus, under the experimental conditions applied in the present study, ER1 provided Artemia with DHA and EPA ratio of 4.1 for early feeding of Pacific cod larvae.

Nutritional programming improves dietary plant protein utilization in zebrafish Danio rerio.

Nutritional Programming (NP) has been shown to counteract the negative effects of dietary plant protein (PP) by introducing PP at an early age towards enhancement of PP utilization during later life stages. This study explored the effect of NP and its induction time on growth, expression of appetite-stimulating hormones, and any morphological changes in the gut possibly responsible for improved dietary PP utilization. At 3 days post-hatch (dph) zebrafish were distributed into 12 (3 L) tanks, 100 larvae per tank. This study included four groups: 1) The control (NP-FM) group received fishmeal (FM)-based diet from 13–36 dph and was challenged with PP-based diet during 36–66 dph; 2) The NP-PP group received NP with dietary PP in larval stage via live food enrichment during 3–13 dph followed by FM diet during 13–36 dph and PP diet during 36–66 dph; 3) The T-NP group received NP between 13–23 dph through PP diet followed by FM diet during 23–36 dph and PP diet during 36–66 dph; and 4) The PP group received PP diet from 13–66 dph. During the PP challenge the T-NP group achieved the highest weight gain compared to control and PP. Ghrelin expression in the brain was higher in T-NP compared to NP-FM and NP-PP, while in the gut it was reduced in both NP-PP and T-NP groups. Cholecystokinin expression showed an opposite trend to ghrelin. The brain neuropeptide Y expression was lower in NP-PP compared to PP but not different with NP-FM and T-NP groups. The highest villus length to width ratio in the middle intestine was found in T-NP compared to all other groups. The study suggests that NP induced during juvenile stages improves zebrafish growth and affects digestive hormone regulation and morphology of the intestinal lining–possible mechanisms behind the improved PP utilization in pre-adult zebrafish stages.

Effects of Extended-Rotifers Inclusion and Live Food-Enrichment with Probiotics on the Survival, Metamorphosis, Development Time and Growth of Mud Crab, Scylla paramamosain (Estampador) Larvae

The present larval nutrition study was conducted to evaluate the effects of feeding probiotic-enriched rotifers inclusion mixed with Artemia until zoeal stages 4 (Z4) and Z5 on the survival, metamorphosis, development time and growth of mud crabs, Scylla paramamosain larvae. The efficiency of the feeding regime was tested by two-factor analysis. A 4&times;2 factorial experimental design with eight combinations of enriched or un-enriched or a mixture of enriched and un-enriched live food (factor 1) in each of two feeding regimes (factor 2) in triplicate was setup. After 24 days of larval cultivation, there were no significant (p>0.05) interactive effects between the two selected factors on survival and metamorphosis rate of larvae. Larval survival in all treatments, under both factors, decreased gradually (p<0.05) during the cultivation period. From 15 Days After Hatching (DAH), the survival and metamorphosis rates of larvae fed both enriched rotifers and Artemia were higher (p<0.05) than those of the larvae without enriched live food. Similarly, from 18 DAH onwards, the extension of rotifers inclusion mixed with Artemia until Z5, irrespective of enrichment, showed higher (p<0.05) survival, metamorphosis and growth of megalopa than when the rotifers were included only until Z4 stage. Overall, an amalgamation of extending rotifer feeding and enriching them at the same time with Artemia can result in considerable improvements in survival and metamorphosis which can in turn, have beneficial impact on the technical feasibility of a commercial crab hatchery.

The impact of live food enrichment on the growth performance and survival rate of thin-lipped mullet, Liza ramada larvae

The impact of live food enrichment on the growth performance and survival rate of thin-lipped mullet, Liza ramada larvae

Effects of Live Food enrichment on Yellowtail Amberjack Seriola lalandi dorsalis (Gill 1863) Larvae

Our study examined the effect of live food enrichment on the rearing performance of yellowtail amberjack Seriola lalandi dorsalis from day 3 posthatch (DPH) to 12 DPH. Three rotifer enriched treatments, 1) Nannochloropsis sp, 2) S.presso® (INVE Aquaculture) half dose (Sp1/2), and 3) S.presso® full dose (Sp1) were administered. Growth of yellowtail amberjack larvae was not significantly affected by these enrichments (P&gt;0.05) but final survival rates were significantly affected (P&lt;0.05). Jaw malformation of fish fed with only Nannochloropsis sp. enriched rotifers was significantly higher than those fed S.presso enriched rotifers. Fatty acid composition of rotifers was significantly affected by the enrichment treatments (P&lt;0.05). Arachidonic acid (ARA, 20:4n-6) and Eicosapentaenoic acid (EPA, 20:5n-3) were highest in rotifers enriched with Nannochloropsis. Docosahexaenoic acid (DHA, 22:6n-3) level was highest in Sp1 treatment. Total saturated fatty acids in rotifers was not significantly affected (P&gt;0.05), but total polyunsaturated fatty acid content was significantly affected (P&lt;0.05) by enrichment. DHA/EPA ratio in rotifers was significantly affected by the enrichment (P&lt;0.05). Highest total polyunsaturated fatty acids were observed in rotifers enriched with Sp1. On 12 DPH, fatty acid composition in the larvae was significantly affected by the nutrient enhancement (P&lt;0.05). ARA and EPA levels were highest in the larvae fed with Nannochloropsis sp. enriched rotifers; highest DHA/EPA ratio in fish larvae was found in Sp1 treatment. Total polyunsaturated fatty acid in the larvae enriched with Sp1/2 and Sp1 was similar to the amount observed in fertilized eggs of yellowtail amberjack (P&gt;0.05). Results indicate that enriched live feed can significantly affect rearing performance of yellowtail amberjack larvae; S.presso full dose enrichment is suitable for their initial rearing stages.

The effect of live food enrichment with docosahexaenoic acid (22:6n-3) rich emulsions on growth, survival and fatty acid composition of meagre (Argyrosomus regius) larvae

While spawning induction and larval rearing of meagre (Argyrosomus regius) have advanced as forcing factors to move this finfish species into the commercial aquaculture sector, larval nutrition still has unanswered issues to address, specifically in regard to live prey enrichment and fatty acid composition. In this study, two experimental trials for larval rearing of meagre utilizing different methods of live prey enrichment with emulsions of different specialist oils having distinct fatty acid composition, have demonstrated that docosahexaenoic acid (DHA) requirements may be species-specific, with a DHA supplement of 12–15% in live prey enrichment diets yielding optimum larval growth. Cannabilism in early life stages (post 20dph) in this species also remains a challenge and requires stocks to be managed accordingly. Further, we found evidence suggesting meagre larvae are not capable of elongation or desaturation of fatty acids when precursors such as LA, GLA, LNA or SDA are offered in the live prey.

A novel approach to introduce nutrients into the fish egg; the effect of egg taurine on first feeding gilthead sea bream (Sparus aurata) performance

A potential key ingredient in broodstock and larval nutrition is the beta amino sulfonic acid; taurine. In the present study we investigated a novel application of electroporation-based methodology to introduce nutrients, such as taurine, into fertilized fish eggs with the aim of improving larval performance. In calibration trials, batches of 60 fertilized gilthead sea bream (Sparus aurata) eggs were electroporated in order to evaluate various combinations of voltage (V), time interval (ms) and pulse number. These resulted in egg hatchability and larval survival 24h later that were not significantly (P>0.05) different from the non-electroporated controls. The chosen electroporation protocol demonstrated a more permeable egg membrane by the significantly (P<0.001) higher proportion of eggs incorporating a fluorescein marker in the yolk sac compared to the controls. The selected protocol was used to taurine enrich sea bream eggs in order to determine the effect of taurine level in pre- and exogenous feeding larvae.The taurine content of the taurine electroporated eggs was 6.2× higher (P<0.05) than the control eggs (4.36±2.24 and 0.7±0.02mgg−1 DW, respectively). On the other hand, the taurine level dropped considerably after hatching but was still significantly higher than the control pre-larvae (1.11±0.07 and 0.87±0.04mgg−1 DW, respectively) while the taurine levels in the control and treatment 10days post hatch (dph) larvae were not significantly (P>0.05) different. Taurine treated eggs exhibited a significantly (P<0.01) lower incidence of urinary calculi at 4, 6, 8 and 10dph and a lower frequency (P<0.01) of the larger (>50μm) calculi. Moreover, the control larvae ingested less rotifers, which was significant (P<0.05) at 4dph, than the taurine larvae. Interestingly, larvae from either the control or taurine treatment having large calculi ingested significantly (P<0.01) less rotifers. These results suggest a correlation between the presence of large calculi and reduced prey hunting success. However taurine enrichment of eggs did not promote growth by 10dph larvae suggesting that this technique should be modified to reduce taurine loss at hatching and/or that taurine live food enrichment is also necessary in order to maintain the level of this critical nutrient in early stage larvae. Nevertheless, the present study demonstrated the potential of electroporation as a novel high throughput approach to introduce taurine and/or other critical nutrients into the developing eggs and a potential alternative to costly broodstock dietary supplementation. Statement of relevance to the field of commercial aquaculturePotential alternative to broodstock dietary supplementation.

Stand-alone live food diets, an alternative to culture and enrichment diets for rotifers

Abstract In order to verify the hypothesis that a formulated live food diet could completely substitute any enrichment step, an existing rotifer culture diet was transformed to slowly release the enrichment components such as protein, fat, vitamins and minerals in non-suffocating concentrations. Nutrients being present at metabolizing concentrations allowed not only gut filling but also gradually enriched the tissue of the rotifers without consuming excessive oxygen or compromising health nor reproduction of the rotifers. Similar growth and reproduction figures were registered with the traditional culture diet as with the stand-alone diet in a lapse of 9 weeks corresponding with 15 rotifer cycles and average FCR's of 1.0. The nutritional profile of the rotifers was similar to that of rotifers undergoing a classic enrichment for all major nutrients (protein, HUFA, vitamins) except for some slow enriching nutrients (i.e. taurine, Zn, Se) that could be incorporated successfully thanks to the long term enrichment approach. Besides the nutritional advantage, benefits were noticed on the practical use of the diet (i.e. direct available enriched live food at any moment); the reduced amount of losses and handling of rotifers and the stability in the process thanks to a higher degree of standardization of the operations. These optimizations lead to less damage of the live food resulting in stronger and better quality rotifers.

Poly-ß-hydroxybutyrate content and dose of the bacterial carrier for Artemia enrichment determine the performance of giant freshwater prawn larvae

The beneficial effects of poly-β-hydroxybutyrate (PHB) for aquaculture animals have been shown in several studies. The strategy of applying PHB contained in a bacterial carrier has, however, hardly been considered. The effect of administering PHB-accumulated Alcaligenes eutrophus H16 containing 10 or 80% PHB on dry weight, named A10 and A80, respectively, through the live feed Artemia was investigated on the culture performance of larvae of the giant freshwater prawn (Macrobrachium rosenbergii). Feeding larvae with Artemia nauplii enriched in a medium containing 100 and 1,000mgL(-1) A80 significantly increased the survival with about 15% and the development of the larvae with a larval stage index of about 1 as compared to feeding non-enriched Artemia. The survival of the larvae also significantly increased with about 35% in case of a challenge with Vibrio harveyi. The efficiency of these treatments was equal to a control treatment of Artemia enriched in an 800 mgL(-1) PHB powder suspension, while Artemia enriched in 10mgL(-1) A80, 100mgL(-1) A10, and 1,000mgL(-1) A10 did not bring similar effects. From our results, it can be concluded that PHB supplemented in a bacterial carrier (i.e., amorphous PHB) can increase the larviculture efficiency of giant freshwater prawn similar to supplementation of PHB in powdered form (i.e., crystalline PHB). When the level of PHB in the bacterial carrier is high, similar beneficial effects can be achieved as crystalline PHB, but at a lower live food enrichment concentration expressed on PHB basis.

Is dietary taurine supplementation beneficial for farmed fish and shrimp? a comprehensive review

AbstractTaurine is a neutral β‐amino acid derived from the metabolism of sulphur‐containing amino acids. It is present in high concentrations in animal tissues, especially heart, retina, skeletal muscle, brain, large intestines, plasma, blood cells and leucocytes. Therefore, this amino acid plays significant roles in many physiological functions, including membrane stabilization, antioxidation, detoxification, modulation of immune response, calcium transport, myocardial contractility, retina development, bile acid metabolism, osmotic regulation and endocrine functions. Historically, taurine has not been considered as an essential nutrient for fish. However, recent studies have indicated that taurine synthesis widely differs between fish species and demonstrated that it plays a key role in aquaculture and nutrition of freshwater and marine fish and shrimp. Animal proteins are rich in taurine, whereas plant proteins are taurine‐deficient. Therefore, fish fed plant protein–based food may require exogenous taurine for maintaining their physiological functions. Nevertheless, taurine may be conditionally indispensable for fish and shrimp, depending on dietary protein source, fish species and size, feeding habits, previous histories and the rate of metabolism of its precursors, namely cysteine and methionine. It is my belief that taurine functions in, and benefits for, farmed fish and shrimp are now more than worthy of critical review and analysis. This review summarizes the current knowledge on the roles of taurine in fish, particularly farmed fish and shrimp, with emphasis on taurine structure and biosynthesis, physiological functions, the effects of dietary taurine on fish performance and health and live food enrichment with taurine.

The effects of tank colour, live food enrichment and greenwater on the early onset of jaw malformation in striped trumpeter larvae

A high incidence of jaw malformation has hindered the production of quality striped trumpeter Latris lineata juveniles and has been correlated with walling behaviour in Artemia-fed larvae. In this study, striped trumpeter were reared from first feeding to 29days post-hatching (dph) in different coloured tanks (black or white), culture conditions (clear or greenwater) and fed different diets (enriched or non-enriched rotifers and Artemia), to examine behaviour, retinoid receptor gene expression and jaw malformation. The highest incidence and severity of jaw malformations occurred in clearwater and enriched diet treatments and were significantly more common in white (70±15%, mean±SD) than in black tanks (26±15%). In black tanks, jaw malformation was significantly more common in larvae fed enriched diets (18±14%) than in those fed non-enriched diets (8±8%) and in clearwater (19±14%) versus greenwater (7±6%). At the end of the rotifer feeding phase, larvae were significantly larger in black than white tanks, and longer in greenwater than in clearwater. In the Artemia feeding phase, larval growth was slowest and mortality was highest in non-enriched diet treatments. Larval length and survival were higher in black tanks and in enriched diet treatments, whilst survival was almost twice as high in greenwater (46±18%) than clearwater (26±13%). The average proportion of larvae walling over the duration of the experiment was higher in white than black tanks, and higher in enriched than non-enriched treatments, with lowest walling in greenwater. There was no consistent relationship between feed intake and jaw malformation. However, there was a significant positive correlation between walling and the incidence of jaw malformation at 29dph in larvae fed enriched diets. The expression pattern of three retinoid receptor genes indicated that live feed enrichment and stress could potentially perturb retinoic acid-associated pathways leading to skeletal abnormality. We found that the use of greenwater, black tanks and enriched live feeds is required for good growth, development, survival and final yield of striped trumpeter. The study emphasises the importance of reducing walling in the culture of oceanic larvae and may have direct application in the rearing of other marine fish with similar malformations.

Using the Live Food Enrichment with the Squid Egg Extract on the Quantity and Quality of Rotifer, Brachionus plicatilis O.F. Muller

The Objective of the research was to know the effect of live food enrichment of rotifer with squid egg extract on the growth patterns and quality of rotifer, especially the EPA and DHA contents. The experiment method was employed in this research and it carried out in the aquaculture laboratory, Faculty of Fisheries and Marine Sciences, Diponegoro University. The research planning was a completely randomized design with five treatments and three replicates, respectively. The recording data was analyzed to get the variables of rotifer growth patterns and the most of rotifer samples were analyzed EPA and DHA contents in the chemical and biochemical laboratory center, Gajah Mada University. The results showed that the addition of squid egg extract in the culture media of rotifer was highly significant effect (p<0.01) on the specific growth rate, the maximal density, and the final density of rotifer culture. However, there was also highly significsnt effect (p<0.01) on the nutrition quality through EPA and DHA contents. To increase the quantity and quality of rotifer, B. plicatilis O.F. Muller in the culture was addition of squid egg extract of 1,2 g/1 million ind. Rotifers during twelve two hours in the rotifer culture. Key word : Rotifer, Brachionus plicatilis O.F. Muller, enrichment, quantity and quality, EPA dan DHA

양식산 넙치, Poralichthys olivaceus의 가성 백색증 (pseudo-albinism) 발현에 미치는 환경인자들의 영향

We examined the cause of albinism in a hatchery population of flounder in terms of environmental and nutritional factors, including the effects of light intensity (130-12,300 lux), photoperiod (12L/12D or 24L/0D), tank substrate (concrete or fiber-reinforced polymer), tank color (white or dark green) and supplement with enriched live food, and also compared the growth of normal and albino fry under both 12L/12D and 24L/0D. Further to, normalization of the skin pigmentation pattern on the ocular side has been juvestigated after rearing the albino fry for 2 years after their identification and classification and found that, light intensity did not play a critical role in the development of normal pigmentation or albinism in the flounder. By contrast, the photoperiod was a weak inducer of albinism in the flounder. Tank substrate and color also affected the hypomelanosis on the ocular side of the flounder fry. The choice and supplementation of enriched live foods could drastically reduce the incidence of albinos in hatcheries. On comparing the growth of normal and albino fry, while there was no difference between the groups under 24L/0D, the growth of the albino flounder was slower under 12L/12D. Although coloration resulting from xanthophore and melanophore, but not iridophores, occurred on the ocular side, evidence of albinism remained on the ocular side of flounders.

A Simple Method for Mass-Production of Liposomes, in Particular Large Liposomes, Suitable for Delivery of Free Amino Acids to Filter Feeding Zooplankton

In marine fish larviculture the live feed organisms are often enriched in order to enhance their nutritional value. One of the challenges is to enhance the phospholipids (PL) content, and another is to enhance the content of specific water soluble nutrients, like free amino acids (FAA). There are a few studies where this has been achieved by the use of liposomes. The aim of this study was to develop a simple method for mass-production of liposomes within a size range of 1–5 μm a size range suitable to feed live food organisms. Furthermore, the liposomes should have a high FAA concentration and be stable under conditions typical for short-time enrichment of live feed organisms. The method used in the present study is based on a combination of a reverse-phase evaporation method for preparing liposomes and re-hydration of freeze-dried, empty liposomes. The liposomal membrane was made of soy phosphatydilcholine and was loaded with a highly concentrated free amino acids solution. Most of the liposomes produced were 2–8 μm in diameter and the FAA encapsulation efficiency was 42.6%. Two experiments simulating 2 hr of live food enrichment were used to evaluate the liposomes. The results showed the liposome did not disintegrate or aggregate when suspended in seawater and that only 9% of the FAA content of the liposomes was lost after 2 hr suspension. The developed method was easy and reliable, producing tens of grams of liposomes per batch.

Effect of supplemental l-ascorbyl-2-polyphosphate in enriched live food on the antioxidant defense system of Penaeus vannamei of different sizes exposed to ammonia-N

The effects of supplemental l-ascorbyl-2-polyphosphate (APP) in enriched live food (Artemia) on reactive oxygen intermediate (ROI) and free radical scavenging enzyme (superoxide dismutase, catalase, glutathione peroxidase, glutathione reductase and glutathione transferase) activities in the muscle of Penaeus vannamei of two sizes exposed to ambient ammonia-N, were investigated. Significantly, decreased ROI value was found in prawns fed on enriched Artemia compared with those fed on starved Artemia (P < 0.05); the decrease was 24% and 36%, respectively. In both size classes, the antioxidant enzyme activities in prawns fed on enriched Artemia were higher than in those fed on starved Artemia (P < 0.05). The results demonstrated that the supplementation of ascorbic acid in enriched live food (Artemia) enhanced the antioxidant capacity of prawn, increasing its defense system that may fight against environmental stress, leading to impaired ammonia toxicity.

Effect of supplemental l-ascorbyl-2-polyphosphate (APP) in enriched live food on the immune response of Penaeus vannamei exposed to ammonia-N

The effects of supplemental vitamin C, in the form l-ascorbyl-2-polyphosphate (APP) in enriched live food dietary ( Artemia) on reactive oxygen intermediates (ROIs) and free radical scavenging enzymes (such as superoxide dismutase, catalase, glutathione peroxidase, glutathione reductase and glutathione transferase) activities in muscle of Penaeus vannamei exposed to ambient ammonia-N were investigated. The results showed ROIs values of shrimps fed the starved and enriched Artemia increased with increased ammonia-N concentration. The ROIs value of shrimps fed the enriched Artemia exposed to increasing ammonia-N concentration were 37.4%, 26.4% and 31.1% lower ( P < 0.05) compared with those of shrimps fed the starved Artemia exposed to the same ammonia-N concentration. Total SOD, CAT, GPX, GST and GR activities of shrimps fed the enriched Artemia exposed to ammonia-N (2.568–3.852 mmol/l), were all higher ( P < 0.05) than that of shrimps fed the starved Artemia exposed to the same ammonia-N concentration. In addition, total SOD, CAT, GPX, GST and GR activities of shrimps of both dietary treatments decreased ( P < 0.05) with increased ammonia-N concentration. The results demonstrated that supplementation of ascorbic acid in enriched live food ( Artemia) enhanced the anti-oxidant capacity of shrimp, increasing its defense system that may fight against environmental stress leading to reduced ammonia toxicity.

Effects of docosahexaenoic, eicosapentaenoic, and arachidonic acids on the early growth, survival, lipid composition and pigmentation of yellowtail flounder ( Limanda ferruginea): a live food enrichment experiment

The role of dietary ratios of docosahexaenoic acid (DHA, 22:6 n−3), eicosapentaenoic acid (EPA, 20:5 n−3) and arachidonic acid (AA, 20:4 n−6) on early growth, survival, lipid composition, and pigmentation of yellowtail flounder was studied. Rotifers were enriched with lipid emulsions containing high DHA (43.3% of total fatty acids), DHA+EPA (37.4% and 14.2%, respectively), DHA+AA (36.0% and 8.9%), or a control emulsion containing only olive oil (no DHA, EPA, or AA). Larvae were fed differently enriched rotifers for 4 weeks post-hatch. At week 4, yellowtail larvae fed the high DHA diet were significantly larger (9.7±0.2 mm, P<0.05) and had higher survival (22.1±0.4%), while larvae fed the control diet were significantly smaller (7.3±0.2 mm, P<0.05) and showed lower survival (5.2±1.9%). Larval lipid class and fatty acid profiles differed significantly among treatments with larvae fed high polyunsaturated fatty acid (PUFA) diets having higher relative amounts of triacylglycerols (18–21% of total lipid) than larvae in the control diet (11%). Larval fatty acids reflected dietary levels of DHA, EPA and AA while larvae fed the control diet had reduced amounts of monounsaturated fatty acids (MUFA) and increased levels of PUFA relative to dietary levels. A strong relationship was observed between the DHA/EPA ratio in the diet and larval size ( r 2=0.75, P=0.005) and survival ( r 2=0.86, P=0.001). Following metamorphosis, the incidence of malpigmentation was higher in the DHA+AA diet (92%) than in all other treatments (∼50%). Results suggest that yellowtail larvae require a high level of dietary DHA for maximal growth and survival while diets containing elevated AA exert negative effects on larval pigmentation.