Enrichment Diets Research Articles

Larval performance of aquacultured Florida pompano ( Trachinotus carolinus) fed rotifers ( Brachionus plicatilis) enriched with selected commercial diets

Selected rotifer enrichment diets were compared on the basis of growth, survival, and fatty acid content of larval Florida pompano, Trachinotus carolinus L. Two 9-day larval rearing trials were conducted using a recirculating aquaculture system. In Trial 1, two microalgae concentrates ( Isochrysis sp., ISO; and Pavlova sp.), a semi-moist paste (Protein Selco Plus, PS+), and a combination of the three diets were compared. In Trial 2, PS+ and three dry enrichment diets (Ori-Green, OG; Protein HUFA, PH; and AlgaMac 3050, AM) were compared. Larvae were fed rotifers 4 times daily at a rate of 2.5 rotifers/ml/feeding at 2–9 days post-hatch (DPH). Although larval growth in both trials was likely influenced by differences in culture density resulting from variable survival, in Trial 1 at 9 DPH standard length (SL) of larvae fed Pavlova-enriched rotifers (4.60 ±0.39 mm, mean ± SD) was greater ( P < 0.05) than that of larvae fed rotifers enriched with ISO (4.29 ±0.48 mm); and the combined treatment (4.31 ± 0.48 mm) and body depth (BD) of larvae fed Pavlova-enriched rotifers (1.21 ± 0.16 mm) was greater than that of larvae fed rotifers enriched with the combined treatment (1.08 ± 0.18 mm). In Trial 2 at 9 DPH, SL and BD of larvae fed rotifers enriched with PH (5.00 ± 0.23 and 1.24 ± 0.12 mm, respectively) was greater than that of larvae fed rotifers enriched with other diets. Survival of larvae fed rotifers enriched with PS+ was highest in both Trial 1 (24.1 ± 10.2%) and Trial 2 (34.4 ±1.6%) and was significantly greater than that of larvae fed rotifers enriched with Pavlova (7.3 ± 1.6%) and the combined treatment (6.0 ± 1.6%) in Trial 1 and larvae fed rotifers enriched with PH (21.8 ± 6.3%) and AM (14.1 ± 4.9%) in Trial 2. While lipid content and fatty acid composition of PS+ enriched rotifers closely resembled that of pompano yolk-sac larvae, n − 3 HUFA content of PS+ enriched rotifers as well as larvae fed PS+ enriched rotifers was not significantly greater than that of other diets tested in both trials.

Variation in Fatty Acid Composition of Artemia salina Nauplii Enriched with Microalgae and Baker's Yeast for Use in Larviculture

The high content of the essential fatty acids in some microalgae and baker's yeast has made them excellent diets for boosting the fatty acid content of livefood Artemia. The influences of baker's yeast (Saccharomyces cerevisiae) and three microalgae, viz., Chlorella salina, Chaetoceros calcitrans, and Nannochloropsis salina, were tested as diet components in marine livefeed brine shrimp Artemia salina nauplii to improve the polyunsaturated fatty acid (PUFA) composition. Artemia nauplii submerged in these diets for four different enrichment intervals (3, 6, 8, and 24 h) were found to incorporate essential fatty acids, and the percentage composition of different fatty acids was measured in the enriched Artemia nauplii and enrichment diets. N. salina produced higher levels of arachidonic acid (AA, 20:4n6, 9.50%), eicosapentaenoic acid (EPA, 20:5n3, 25.80%), and docosahexaenoic acid (DHA, 22:6n3, 4.18%) as compared to other diets. The total PUFA content of the enriched Artemia by N. salina increased by 56.50% with enrichment periods up to 8 h, followed by a significant reduction in the final 24 h. N. salina yielded Artemia nauplii with considerable EPA (8.05%), AA (14.15%), and DHA (1.85%) after 8 h of enrichment, which are significantly higher levels than in nauplii fed with the other three diets (p = 0.05). The DHA/EPA values in Artemia enriched for 6 h by N. salina and C. calcitrans were found to be, respectively, 88.46 and 25% higher than freshly hatched Artemia. Artemia enriched by C. salina and baker's yeast exhibited a reduction in PUFA content even at 6 h of enrichment. Significant relative decreases in DHA, EPA, and total PUFA in Artemia enriched with all of the diets were apparent, with a corresponding increase in the total saturated fatty acid content (26.95 +/- 9.75%) in the final stages (24 h) of enrichment (p = 0.05).

Improving the Fatty Acid Profile of Fairy Shrimp, Streptocephalus dichotomus, Using a Lipid Emulsion Rich in Highly Unsaturated Fatty Acids

Fatty acids are the largest component of lipids and have become a useful tool in the determination of live feeds to a variety of cultured species. Bioencapsulation is a technique which allows high-level incorporation of desired components (i.e., fatty acids, vitamins, antibiotics, etc.) in live feeds, which in turn can be supplemented to the consumer organisms. The procedure described in the present study serves as a platform of technology for enriching the Streptocephalus dichotomus. Uptake of two enrichment diets (ALGAMAC2000 and DHA-SELCO) by adult S. dichotomus was investigated. The fatty acid profile supports the hypothesis that the enrichment diet increases the level of essential fatty acids, such as linolic, linolenic, eicosapentenoic, and docosahexaenoic acids. The average content (percent of total fatty acids detected) of the enriched organism by different highly unsaturated fatty acid (HUFA) products were as follows: ALGAMAC2000 showed 14-22% saturated fatty acid (SFA), 17-18% monounsaturated fatty acid (MUFA), 28-41% polyunsaturated fatty acid (PUFA), 23-34% n-3, and 4.9-7.5% n-6, whereas DHA-SELCO showed about 20-23% SFA, 20-26% MUFA, 38% PUFA, 28-31% n-3, and 7.5-10% n-6. Our present investigation proves that both HUFA-rich diets appear to be an appropriate enrichment diet, and further provides an additional rationale for using fairy shrimp as a maturation diet for any cultivable freshwater organism.

Use of the brine shrimp, Artemia spp., in marine fish larviculture

Since no artificial feed formulation is yet available to completely substitute for Artemia, feeding live prey to young fish larvae still remains essential in commercial hatchery operations. The nutritional quality of commercially available Artemia strains being relatively poor in eicosapentaenoic acid (EPA, 20:5 n-3) and especially docosahexaenoic acid (DHA, 22:6 n-3), it is essential and common practice to enrich these live prey with emulsions of marine oils. In Artemia, the most commonly applied boosting technique is a 24-h enrichment period after hatching. However, the variability of enrichment studied in one Artemia strain (Great Salt Lake, Utah, USA) by the ICES Working Group on Mass Rearing of Juvenile Fish, showed a high variability in fatty acid bioaccumulation under laboratory or commercial conditions. To avoid the variation originating from differences in commercial preparations, standardized ICES emulsions with different HUFA and DHA/EPA ratios have been formulated and are available for research purposes. It should be emphasized, however, that the enrichment technique has limitations as Artemia are selectively catabolizing some of the nutrients such as DHA and phospholipids. Research on the kinetics of DHA catabolism in various Artemia strains has shown that DHA catabolism is strain-dependent and could partially be overcome by the use of strains of different geographical origin. Nowadays, various enrichment emulsions have been formulated differing in the fatty acid composition of their triglycerides. In this respect, the traditional formulations rich in EPA have been replaced by new products rich in DHA and arachidonic acid. To reduce the risks for oxidation of these fatty acids, higher concentrations of vitamin E are incorporated into the emulsions. Also, vitamin C has been incorporated in booster formulations that increase the level of ascorbic acid in Artemia to 2000 ppm. All these changes in the formulation of the enrichment diets offer more possibilities to cover the needs of different species and help to reduce problems related to diseases, stress resistance, malformation, and pigmentation in numerous fish species. Although continuous disinfection of Artemia during hatching and enrichment is becoming a routine operation in many hatcheries, the interference of bacteria in hatching and enrichment remains an important study object for which probionts might also give some solutions. As more attention is given to the use of on-grown Artemia as a cheaper alternative to the use of nauplii, simple cost-effective production techniques have been developed. The use of the right size of on-grown Artemia for feeding ensures a better energy balance in food intake and assimilation, thereby improving the performance of the fish. Furthermore, its palatability induces a good and fast feeding response. These characteristics, coupled with the use of bioencapsulation techniques to enhance the quality of the on-grown Artemia, make this organism an optimum diet for nursery of the fish.

Effects of DHA-enriched live food on growth, survival and incidence of opercular deformities in milkfish ( Chanos chanos)

The use of commercial enrichers to improve the nutritional quality of live food in larviculture of milkfish was investigated. Fish were either fed rotifers cultured on Chlorella sp. and newly hatched Artemia nauplii (Control, Trt I) or rotifers and Artemia given DHA enrichment diets (DHA-treated, Trt II). Results showed survival was significantly better ( P<0.05) in the DHA-treated fish than in the untreated fish after 25-day culture period. Although growth was not statistically different ( P>0.05) between the control and DHA-treated fish during the hatchery phase, extensive rearing of the postlarvae (fry) in nursery ponds for another 60 days showed that DHA-treated fish exhibited significantly better ( P<0.05) growth than the untreated fish. Opercular deformities in 85-day old milkfish juveniles were also significantly lower ( P<0.05) in the DHA-treated fish than the control. Survival after nursery culture, however, was high for both treatments but not significantly different ( P>0.05). The lack of a viable and reliable method of mass culturing copepods as live food in the hatchery makes the use of off-the-shelf commercial enrichment diets for rotifers and Artemia a practical option in the larval culture of milkfish.

Enhanced absorption of docosahexaenoic acid (DHA, 22:6n-3) in Artemia nauplii using a dietary combination of DHA-rich phospholipids and DHA-sodium salts

The effects of surface-active agents such as phospholipids (PL) and salts of long chain fatty acids in enrichment lipids on emulsification, and hence digestion and absorption of essential fatty acids (EFA) were studied. The advantages obtained by using a mixture of docosahexaenoic acid (DHA, 22:6n-3)-rich phospholipids (DHA-PL) and DHA-salts in the process of live feed enrichment are reported on. Enrichment diets at equal levels of DHA, but with varying proportions of DHA-rich triacylglycerols (DHA-TAG), DHA-PL and DHA-sodium salt (DHA-Na) isolated from heterotrophicaly grown Crypthecodinium sp . algae were fed to instar-II stage Artemia nauplii. Artemia nauplii survival and lipid content after 16 h of enrichment were 74.0±7.8% and 24.3±0.6% (dry weight) respectively, and not significantly affected ( P>0.05) with increasing dietary quantities of PL and DHA-salts (up to 40 and 30%, respectively). Artemia lipid class composition was independent of dietary phospholipid level. However, higher proportions of polar lipid fraction was evident in Artemia lipids with the addition of DHA-Na. Dietary inclusion of 20% PL or a mixture of 10% PL and 10% DHA-Na resulted in maximal ( P<0.05) absorption of dietary DHA by the Artemia (27.5±2.6 mg/g dry weight) with a DHA to eicosapentaenoic acid (EPA, 20:5n-3) ratio greater than 3. Furthermore, PL was the most efficient dietary fraction to deliver DHA to Artemia nauplii as compared to TAG or unesterified delivery forms.

Manipulation of dietary lipids, fatty acids and vitamins in zooplankton cultures

1. A wide range of species that are cultivated in commercial mariculture are planktonic during at least part of their life cycle; for example, the larval stages of shellfish (shrimp and molluscs) and the live feeds (rotifers, brine shrimp, copepods) used in the larviculture of marine fish and shellfish. Over the last decades various techniques have been developed to deliver nutrients to these zooplanktonic organisms either through artificial diets or by manipulating the composition of the live prey fed to the carnivorous stages. This paper reviews the methodology that has allowed aquaculturists to gain knowledge of nutritional requirements and may offer interesting opportunities for ecologists to verify the importance of key nutrients in the natural food chain of marine as well as freshwater ecosystems.2. Live micro‐algae can be replaced partially or completely in the diet of filter‐feeders such as rotifers, Artemia, shrimp larvae and bivalves, by various types of preserved algae, micro‐encapsulated diets and yeast‐based diets, whereas lipid emulsions and liposomes may be utilized to supplement specific lipid‐and water‐soluble nutrients, respectively. Microbound and micro‐encapsulated diets have been designed to supplement live feed in the culture of micro‐predators such as fish and shrimp larvae.3. Live prey organisms, in particular rotifers and Artemia, can be ‘bio‐encapsulated’ with a variety of enrichment diets to manipulate their content in certain nutrients, including ω3 highly unsaturated fatty acids (FA) and the vitamins C, A and E. Nevertheless, the enrichment techniques are not applicable for all nutrients and prey organisms. Phospholipid composition is difficult to manipulate through the diet of live feed and the enrichment of the essential FA docosahexaenoic acid (DHA) is hampered in most Artemia species due to the catabolism of this FA following enrichment.

Two novel Anemia enrichment diets containing polar lipid

Two novel Anemia enrichment diets were tested against control diets of Super Selco (SS) (Artemia Systems, INVE, Ghent) and baker's yeast. The first experimental diet consisted of tuna orbital oil emulsified with 12% herring roe polar lipid (P-T). The second test diet comprised liposomes incorporating the phosphatidylcholine (PC) fraction of herring roe. Enrichment efficiency was measured in terms of lipid class and fatty acid composition of enriched nauplii, with particular attention being paid to PC content, docosahexaenoic acid (DHA) levels and DHA:eicosapentaenoic acid (EPA) ratios. The P-T emulsion yielded Artemia nauplii with 14% DHA (% total fatty acids) and a DHA:EPA ratio of 1.8, significantly higher than in nauplii fed the other three diets. Polar lipid levels in both P-T and SS enriched nauplii were similar (32.4 mg g −1 and 34.7 mg g −1 dry body weight (DBW) of nauplii, respectively). Lower %DHA and DHA:EPA ratios were obtained in liposome-fed nauplii (2% and 0.3, respectively) However, they yielded significantly higher levels of naupliar polar lipid (40.1 mg g −1 DBW) than those fed the two oil emulsion treatments. The significance of these findings is discussed.

Effect of degree of unsaturation in dietary fatty acids on arachidonic acid mobilization by peritoneal macrophages

Cells from rats fed with a tripalmitin diet showed a depletion of phospholipid arachidonate and n-3 fatty acids such as eicosapentaenoic and docosahexaenoic acids (EPA and DHA). In rats fed fish oil diet, a significant reduction in arachidonic acid (AA) content was observed whereas EPA and DHA were incorporated into membranes lipids. These changes in lipid composition of membranes did not affect cellular adherence, phagocytic capability, or [3H]AA incorporation. However, both tripalmitin and fish oil diets induced a decrease in [3H]AA mobilization stimulated by 4 beta-phorbol-12-myristate 13-acetate, A23187, or opsonized-zymosan in rat peritoneal macrophages. These results demonstrate that the antiinflammatory effects of essential fatty acids deficiency or n-3 enrichment diets may be associated with a decreased AA mobilization in resident rat peritoneal macrophages treated with proinflammatory agents.

Improving the n − 3 HUFA composition of Artemia using microcapsules containing marine oils

Preparation of gelatin-acacia microcapsules containing cod liver oil or squid oil, and their use for highly unsaturated fatty acid (HUFA) enrichment of Artemia nauplii is described. These microcapsules were readily ingested by Artemia nauplii and were visible in the gut a few minutes after the start of enrichment. Ingestion of microcapsules containing cod liver oil or squid oil resulted in a significant increase in the HUFA content of nauplii after only 1 h. The level of HUFA enrichment was influenced by the density of nauplii during the enrichment procedure; a reduction in the density of nauplii resulted in a large increase in their HUFA content. The levels of HUFA enrichment achieved in this study compare well with similar studies. Gelatin-acacia microcapsules containing marine oils are a suitable means for HUFA enrichment of Artemia; they allow inexpensive enrichment diets to be made on-site and may offer a cheaper alternative to commercial enrichment preparations.

The Influence of Different Rotifer and Artemia Enrichment Diets on Growth, Survival and Pigmentation in Turbot (Scophthalmus maximus L.) Larvae

AbstractAn experiment was carried out on turbot larvae fed three different rotifer enrichment diets: Dry Selco, Protein Selco and ICES low‐HUFA (an enrichment emulsion containing low amounts of highly unsaturated fatty acids—HUFA). Seven tanks were set up for each diet. After the rotifer stage, approximately seven days after hatching, the larvae were fed newly‐hatched Artemia salina nauplii (AT‐1; Brazil strain). From day 10, enriched Great Salt Lake Artemia nauplii were introduced. Each set of seven tanks was further subdivided and the larvae fed Arternia nauplii enriched with one of four enrichment diets: Dry Selco, Protein Selco, ICES low‐HUFA or Super Selco. The rotifer enrichments had no significant effect on larval growth and survival. The nutritional value of the Artemia stage (day 13 to 26) was more important for the overall larval survival.

Larviculture of Mediterranean Marine Fish Species: Current Status and Future Trends

AbstractThe larviculture of Mediterranean marine fish species has focused on the production of Spurus auruta and Dicentrarchus labrar. European fry production of these species has increased from 12 million in 1987 to 28 million in 1989 and is expected to rise to nearly 40 million fry in 1990.Within differing hatchery systems, larval survival has been improved through the use of commercially available w3‐HUFA rich live food enrichment diets. This combined with the use of surface cleaning techniques has led to a standardization of larval rearing procedures enabling mass production of quality fry. Increased concern with larval hygiene has resulted in larger larval rearing batch production and regular sterilization periods in most European units.Market pressure is stimulating established producers to diversify their species range and industrial quantities of Puntazzo puntuzzo, and Pagrus major are already being produced. Work has started on the larval culture of Dentex dentex, Pagrus pagrus and Seriola dumerilli.

The effect of enrichment diets on the fatty acid composition of the rotifer Brachionus plicatilis

Cultures of the rotifer Brachionus plicatilis (200 ind./ml, 0.5 μg dry weight/ind.) pre-fed on yeast and capelin oil (10:1 w/w) were given different enriched diets and harvested after 24 h. The fatty acid composition of the rotifers was affected by that of the feed. The highest level of n−3 highly unsaturated fatty acids (HUFA) 38%) and 22:6 n−3 (19%) was obtained after enrichment of the rotifers fed with squid meal. A positive relation was found between the n−3 HUFA in the enrichment diet and that of the rotifers ( P < 0.05, t-test). The cultivation feed of the rotifers may nevertheless be more important for the n−3 HUFA level than the enrichment feed. Starvation for 49 h did not change the fatty acid composition of the rotifers.