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1.
Performance of phyllosoma of thesouthern rock lobster (Jasus edwardsii)was examined after feeding Artemia-baseddiets. Survival and growth of newly-hatchedlarvae cultured to Stage III were lower(p < 0.05) when fed 0.8 mm Artemia than1.5 mm or 2.5 mm Artemia alone or 1.5 mmArtemia in combination with pieces ofmussel (Mytilus edulis planulatus) gonad.This could not be attributed to deficiencies inthe composition of fatty acids but appeared tobe due to the inability of larvae to capturesufficient appropriate-sized, enrichedArtemia for their nutritional requirements.There was an indication that survival andgrowth were higher between Stages III and Vwhen fed 2.5 mm Artemia than 1.5 mmArtemia alone or in combination with musselpieces. However, Stage VI larvae grew to asimilar size at Stage VIII when fed 1.5 mm or2.5 mm Artemia. Unexpectedly, larvae fedthe combination of 1.5 mm Artemia plusmussel supplement had lower survival than foundpreviously, and generally lower than when fed 1.5 mm Artemia alone. This was despitean apparent nutritional profile (lipid contentand fatty acid composition) of mussel more akinto that of newly-hatched phyllosoma thanenriched Artemia. On the other hand,survival and growth to Stage VIII were higherwhen larvae were fed alginate pelletscontaining Artemia than when fed 1.5 mmor 2.5 mm Artemia alone.  相似文献   

2.
Fatty acid analyses were conducted on newly hatched and 8‐day‐old‐starved and fed Stage I phyllosoma larvae of the spiny lobster, Jasus edwardsii. Fed animals were offered excess 1.5 mm juvenile Artemia (enriched using the alga Isochrysis galbana, Tahitian isolate, T. iso.). After 8 days, there were significant increases in larval dry weight and the proportion of lipid in fed phyllosoma, whereas these parameters decreased in starved phyllosoma. The abundance of the saturated fatty acids 16 : 0 and 18 : 0 increased in both starved and fed phyllosoma, whereas the main monounsaturated fatty acids 16 : 1n‐7, 18 : 1n‐9 and 18 : 1n‐7 increased with feeding but decreased with starvation. There were no significant differences in the relative proportions of the highly unsaturated fatty acids (HUFAs) arachidonic (AA, 20 : 4n‐6), eicosapentaenoic (EPA, 20 : 5n‐3) and docosahexanoic (DHA, 22 : 6n‐3) acids between newly hatched and starved animals, whereas quantitatively DHA decreased with starvation and feeding. The DHA/EPA ratio was significantly lower in the starved and fed phyllosoma (0.5) compared with that found in the newly hatched phyllosoma (0.9). The lipid profiles of the newly hatched, starved and fed phyllosoma contained large amounts of n‐6 fatty acids resulting in low n‐3 : n‐6 ratios (2.8, 2.7 and 1.6 respectively). The importance of these results and the ability of enriched Artemia to provide a suitable fatty acid profile for this species are discussed.  相似文献   

3.
Western rock lobster, Panulirus cygnus, phyllosoma were grown from hatching to stage IV. Larvae were fed with Artemia enriched with a (i) base enrichment (Base) containing 520 g kg?1 squid oil or tailor made enrichments in which oils high in polyunsaturated fatty acid (PUFA) have been added at the expense of squid oil. These treatments were (ii) base enrichment supplemented with docosahexaenoic acid (DHA) rich oil, (iii) base enrichment supplemented with arachidonic acid (AA) rich oil, or (iv) base enrichment supplemented with DHA and AA (D + A) rich oils. Total survival of phyllosoma to stage IV was high, with no significant difference between treatments (range 12.3–17.5%). By stage IV, the larvae fed the DHA or AA enriched Artemia were significantly larger (3.33 mm length) than larvae fed the Base or D + A enriched Artemia (3.18–3.24 mm length). Phyllosoma were sampled at stages II and III for biochemical analysis. The major lipid class (LC) in all phyllosoma was polar lipid (PL) (88.9–92.4%), followed by sterol (ST) (6.2–9.7%). Triacylglycerol (TAG), free fatty acid (FFA) and hydrocarbon/wax ester were minor components (≤1%) in all phyllosoma samples. In contrast, the major LC in all enrichments and enriched Artemia was TAG (76.3–85.1% and 53.4–60.2%, respectively), followed by PL (11.4–14.8% and 30.6–38.1% respectively). The main fatty acids (FA) in phyllosoma were 16:0, 18:1n‐9, 18:1n‐7, 18:0, AA, eicosapentaenoic acid (EPA) and DHA. Addition of AA, and to a lesser extent DHA, to enrichments resulted in increased levels of those FA in Artemia and phyllosoma compared with the Base enrichment. This was particularly evident for stage III larvae. Comparatively, elevated growth for phyllosoma to stage IV was achieved with DHA and AA enriched diets. Our findings highlight the importance of lipids and in particular essential long‐chain PUFA, as nutritional components for phyllosoma diets.  相似文献   

4.
Newly hatched Jasus edwardsii phyllosoma were fed unenriched Artemia [endogenous ascorbic acid (AA) concentration of 166 μg g?1 dry weight (dw)], Artemia supplemented with algae (AA concentration 594 μg g?1 dw) or with ascorbyl‐2‐polyphosphate (A2P) (AA concentration 11 737 μg g?1 dw) to examine possible benefits of AA enhancement on culture. Plain or algal‐enriched Artemia were fed continuously for 28 days in two treatments during the study. Four other treatments received A2P‐enriched Artemia on a progressive basis starting from the commencement of the trial (D‐0), the third (D‐3), sixth (D‐6) or ninth day (D‐9) of Stage I (14 days) and similarly during Stage II (14 days). Prior to the commencement of A2P supplementation, plain Artemia were supplied to these animals. By Stage III (28 days feeding), algal, D‐0 and D‐3 phyllosoma had attained the largest size. The uptake and retention of AA by Stage III phyllosoma appeared to be dose‐dependent with the highest concentration of AA incorporation evident in D‐0 phyllosoma (1816 μg g?1 dw), while algal and plain phyllosoma contained the lowest concentrations (600 and 300 μg g?1 dw, respectively). Survival at Stage III was highest in D‐0 phyllosoma (89%) and lowest in plain phyllosoma (51%). There was a positive relationship between phyllosoma AA concentration and larval survival (R2 = 0.8328, P < 0.0001). D‐0 phyllosoma had the lowest stress index when subjected to an osmotic/temperature activity test, indicative of better survival in culture compared to plain, algal and D‐9 phyllosoma, which had consistently higher indices. A negative relationship existed between phyllosoma AA concentration and stress indices at Stage III (R2 = 0.9263, P < 0.0001), suggesting that AA from the Artemia diet conferred stress resistance.  相似文献   

5.
Newly hatched phyllosoma larvae of Jasus edwardsii were on‐grown to stage V. Using triacylglycerol‐rich marine oil nutrient sources and microalgae, Artemia were enriched with the major polyunsaturated fatty acids (PUFA) to ratios similar to that of wild‐caught phyllosomata. Artemia enriched by different methods were fed to cultured phyllosomata. At each stage animals were counted, measured and sampled for lipid analyses. Survival was highest from stages II to III (62–86%), with mean total survival at 3–12%. From stages I to V larvae increased in mass (0.2–2.2 mg) and total length (2.1–5.8 mm), and decreased in total lipid. The major lipid class in all phyllosomata was polar lipid, followed by sterol, with no triacylglycerol detected. The main fatty acids were 18:1(n‐9)c, 18:2(n‐6), 16:0, 18:0, eicosapentaenoic acid [EPA; 20:5(n‐3)], 18:1(n‐7)c, arachidonic acid [AA; 20:4(n‐6)] and docosahexaenoic acid [DHA; 22:6(n‐3)]. On‐grown phyllosomata had levels of AA and EPA similar to that of wild phyllosomata, but contained markedly lower levels of DHA. Strategies for enhancement of DHA levels will be needed for culture of rock lobster phyllosomata.  相似文献   

6.
High mortality frequently occurs in larval mass production of Korean rockfish, Sebastes schlegeli Hilgendorf. Nutritional deficiencies in live feeds, rotifers and Artemia nauplii, fed to larvae could be a reason. A series of experiments was carried out to evaluate the effect of nutritional enrichment of live feeds by ω‐yeast, Spirulina powder and Super SelcoTM on survival and growth rates in rockfish larvae. Preference of rockfish larvae for the live feeds was determined by analysis of stomach contents. In addition, the effect of green water produced by the use of Chlorella ellipsoidea and Spirulina powder on the growth performance of larvae was evaluated. Larvae fed rotifers nutritionally enriched with Super Selco showed significantly higher survival rates than those fed rotifers enriched with ω‐yeast. Larvae fed rotifers that were nutritionally enriched with both Super Selco and Spirulina together exhibited improved growth and survival rates. Larvae fed Artemia nauplii nutritionally enriched with Spirulina powder showed significantly higher survival than larvae fed Artemia nauplii without enrichment. When larvae were fed rotifers, Artemia nauplii or the mixture of rotifers and Artemia nauplii, the second and last group showed significantly higher survival than the first group. Fatty acid composition in live feeds was improved by enrichment of ω‐yeast and larvae fed this feed showed higher survival and growth rates compared with larvae fed non‐enriched feeds. No positive effect of green water in the tank produced with C. ellipsoidea or Spirulina powder was observed on survival and growth rates for larvae fed nutritionally enriched rotifers with Super Selco and Spirulina powder. However, when the larvae were fed Artemia nauplii that were nutritionally enriched with ω‐yeast and Spirulina powder, green water obtained by adding Spirulina powder to the tanks resulted in significantly higher growth rates of larvae than was obtained by adding C. ellipsoidea.  相似文献   

7.
Three commercially available fatty acid enrichment emulsions (DC Selco, DC DHA Selco and DC Super Selco) were used to enrich Artemia nauplii fed to seahorse, Hippocampus sp. fry. The emulsions varied in their n-3 highly unsaturated fatty acid (HUFA) composition. Total n-3 HUFA content ranged from 200 to 450mgg-1 between the three emulsions while levels of eicosapentaenoic acid (EPA, 20:5n-3) and docosahexaenoic acid (DHA, 22:6n-3) ranged between 47–220 and 80–190mgg-1, respectively. Survival and growth of seahorses at the end of the 30 day growth trial were greater in treatments receiving enriched Artemia. Seahorses receiving Artemia enriched with DC DHA Selco and DC Super Selco showed significantly (p < 0.05) greater mean survival (71.6 ± 6.0% and 78.3 ± 6.0%, respectively) than those receiving unenriched Artemia (48.3 ± 6.0%). Mean standard length was also significantly greater (p < 0.05) in fry fed DC DHA Selco and DC Super Selco enriched Artemia (20.2 ± 0.3 and 19.7 ± 0.3mm, respectively) compared to those fed unenriched Artemia (18.1 ± 0.3mm). The results show that dietary n-3 HUFA are essential for optimal growth and survival of Hippocampus sp. and, based on the fatty acid compositions of the enriched Artemia used in this study, indicate that the level of dietary DHA supporting optimal growth and survival is greater than 9.3mgDHAg-1 dry weight.  相似文献   

8.
Flatfish metamorphosis is initiated by the actions of thyroid hormones (TH) and iodine is an essential part of these hormones. Hence, an iodine deficiency may lead to insufficient levels of TH and incomplete metamorphosis. In this study, different iodine sources for enrichment of Artemia were evaluated and the levels of iodine obtained in Artemia were within the range of 60–350 μg g?1 found in copepods. Larval Atlantic halibut was fed Artemia enriched with either normal DC‐DHA Selco or DC‐DHA Selco (commercial enrichments) supplemented with iodine from days 9 to 60 postfirst feeding. There was no significant difference in growth, mortality or metamorphic development between the groups. The analyses showed that we were able to enrich Artemia with iodine. Further, the larvae‐fed iodine‐enriched Artemia had higher whole body iodine concentration compared to larvae‐fed Artemia without iodine enrichment.  相似文献   

9.
Different liposome formulations, includingseveral combinations of membrane composition,type of vesicle (multilamellar and largeunilamellar vesicles), preparation method, andvehiculated nutrient, have been assayed asbioencapsulation products to enrich Artemia nauplii with nutrients for feeding fish larvae.The stability of the liposome preparationsunder conditions of use as enrichment producthas been tested using water soluble fluorescentmarkers as leakage indicators. The content ofthe fatty acids and lipid classesbioencapsulated in Artemia nauplii withliposomes has been analyzed by gas and thinlayer chromatography, respectively, andcompared with other enrichment products. Theeffect of the liposome enriched Artemianauplii used as food for fish larvae has beenevaluated in sea bass cultures. Liposomes withhigh content in polyunsaturated fatty acidsleak out more than 50% of their aqueous phasein less than 2 hours, unless they arestabilized with cholesterol and formed as largeunilamellar vesicles. Such vesicles hold70% of the encapsulated material for 8 hours.Liposome enriched nauplii in this study reflectthe influence of the enrichment products,however, they are far from the commercialemulsion (Super Selco) in terms ofdocosahexaenoic acid content, except for thenauplii enriched with liposomes made of purekrill phospholipid extract by the method ofdetergent solubilization. The liposome enrichednauplii show a higher amount of polar lipids incontrast to the feed enriched with emulsions.The larvae fed liposome enriched nauplii haveonly a slightly lower docosahexaenoic acidcontent than those fed emulsion enrichednauplii. The results obtained confirm thesuitable potential use of liposomes as foodsupplement in larviculture. Problems andadvantages are discussed.  相似文献   

10.
Artemia nauplii catabolize polyunsaturated fatty acids (PUFA); in particular, they retroconvert docosahexaenoic acid (DHA, 22:6n‐3), so enrichment is a continuous quest towards increasing PUFA through the use of PUFA‐rich enrichment products. However, optimal conditions during enrichment (aeration, illumination and temperatures around 28°C) tend to accelerate autoxidation of PUFA and the formation of potentially toxic oxidation products. Water‐soluble antioxidants like the polyphenolic compound hydroxytyrosol (3,4‐dihydroxyphenylethanol), a polar molecule found in the water fraction resulting after the milling process of olives, arise as promising compounds to prevent oxidation during Artemia enrichments. We investigated the antioxidant activity and lipid peroxidation in Artemia nauplii during enrichment and the effect of adding an external antioxidant based on hydroxytyrosol during the enrichment with a PUFA‐rich emulsion (M70). For this purpose, the activity of antioxidant enzymes (catalase, superoxide dismutase, glutathione‐S‐transferase, glutathione peroxidase), as well as lipid peroxidation, was determined in enriched and unenriched Artemia nauplii. To validate antioxidant activity and lipid peroxidation, in a first experiment, nauplii were enriched with microalgae (Tetraselmis suecica), yeast (Saccharomyces cerevisiae) and M70 emulsion. In a second experiment, enrichment with a commercial emulsion (DC Super Selco), M70, and a combination of M70 and hydroxytyrosol (Hytolive, HYT) added as an external antioxidant were performed. The combination of M70 with HYT produced the best results, in terms of activity of antioxidant enzymes. The analysis of the fatty acids from total lipids showed that the addition of hydroxytyrosol preserved the DHA percentage of enriched nauplii.  相似文献   

11.
This study aimed to evaluate the effects of enriched Artemia by fish and soybean oils supplemented with vitamin E on growth performance, lipid peroxidation, lipase activity and fatty acid composition of Persian sturgeon (Acipenser persicus) larvae. For this purpose, five experimental diets including non‐enriched Artemia (control diet), Artemia enriched with soybean oil supplemented with 15% and 30% vitamin E (S15 and S30 diets) and fish oil supplemented with 15% and 30% vitamin E (F15 and F30 diets) were used. The larvae were fed to apparent satiation four times per day for 22 days. The results indicated that fish fed enriched Artemia had no significant differences compared with those fed non‐enriched Artemia in terms of growth and survival, but increase in vitamin E levels from 15 to 30% improved growth performance of larvae. Vitamin E content in fish fed S15 and S30 diets was significantly higher. Fish fed non‐enriched Artemia had significantly higher thiobarbituric acid and lower lipase activity. The highest HUFA and n‐3/n‐6 ratio were observed in fish fed F15 and F30 diets. Our results demonstrated that fish oil can completely replace with soybean oil in larval diets. Therefore, using S30 diet is recommended for feeding of Persian sturgeon larvae.  相似文献   

12.
The nematode Panagrolaimus sp. was tested as live feed to replace Artemia nauplii during first larval stages of whiteleg shrimp Litopenaeus vannamei. In Trial 1, shrimp larvae were fed one of four diets from Zoea 2 to Postlarva 1 (PL1): (A) Artemia nauplii, control treatment; (NC) nematodes enriched in docosahexaenoic acid (DHA) provided by the dinoflagellate Crypthecodinium cohnii; (N) non‐enriched nematodes; and (Algae) a mixture of microalgae supplemented in C. cohnii cells. In Trial 2, shrimp were fed (A), (NC) and a different treatment (NS) with nematodes enriched in polyunsaturated fatty acids (PUFAs) provided by the commercial product S.presso®, until Postlarva 6 (PL6). Mysis 1 larvae fed nematodes of the three dietary treatments were 300 μm longer (3.2 ± 0.3 mm) than control larvae. At PL1, control shrimp were 300 μm longer (4.5 ± 0.3 mm) than those fed DHA‐enriched or PUFAs‐enriched nematodes. No differences were observed in length and survival at PL6 between control larvae and those fed DHA‐enriched nematodes (5.1 ± 0.5 mm; 33.1%–44.4%). Shrimp fed microalgae showed a delay in development at PL1. This work is the first demonstration of Panagrolaimus sp. suitability as a complete substitute for Artemia in rearing shrimp from Zoea 2 to PL6.  相似文献   

13.
The effect of enriching rotifer prey with highly unsaturated fatty acids on sunshine bass Morone chrysops × M. saxatilis larval survival and growth from ages 4 to 12 d posthatch was determined. Comparisons were made among larvae fed (1) rotifers cultured with Nannochloropsis paste versus rotifers cultured with Nannochloropsis paste and enriched with Culture Selco 3000; (2) no rotifers versus rotifers cultured with Nannochloropsis paste and enriched with Culture Selco 3000; and (3) rotifers cultured with Nannochloropsis paste and enriched with Culture Selco 3000, rotifers cultured with Nannochloropsis and Pavlova pastes and enriched with Culture Selco 3000, and rotifers cultured with Nannochloropsis paste and enriched with Culture Selco 3000 and Super Selco. The only differences in survival were unfed larvae with practically no survival compared to 55.4% survival for larvae fed rotifers cultured with paste plus Culture Selco 3000. Larvae fed rotifers cultured with paste plus Culture Selco 3000 were longer and had greater condition than those fed rotifers cultured with paste. Additional enrichment with Pavlova sp. or Super Selco had no affect. A canonical analysis of fatty acid contents of diets, rotifers, and fry supported evidence from harvest results. Distances between centroids indicated distinct differences among diets, less distinction among the rotifers, and little difference among fry. Enrichment enhanced growth, but additional enrichment beyond that done during rotifer culture did not increase survival, growth, or condition.  相似文献   

14.
Systemic granulomatosis is the most frequent disease in juvenile and adult meagre, but studies regarding the first appearance of granulomas in larvae do not exist. In order to evaluate this, meagre larvae were fed four different feeding regimes as follows: RS and RO (rotifer enriched with Easy DHA Selco or Ori‐Green from 3 to 30 dph respectively), RAS and RAO (rotifer enriched with Easy DHA Selco or Ori‐Green from 3 to 21 dph and Artemia enriched with Easy DHA Selco or Ori‐Green from 12 to 30 dph respectively). All treatments were also fed with commercial microdiet from 20 to 30 dph. At 30 dph weight, length, specific growth rate and survival were significantly higher in Artemia‐fed larvae, regardless of the enrichment. Microscopic first appearance of granulomas was observed in 20 dph larvae fed RS and RO. At 30 dph granulomas and thiobarbituric acid reactive substances (TBARS), values were significantly higher in RS and RO‐fed larvae than in RAS and RAO‐fed larvae. The results showed that granulomas first appeared in meagre larvae at 20 dph when fed rotifers only. Conversely, a reduced appearance of granulomas and lipid peroxidation occurs when Artemia is included in the feeding sequence reinforcing the hypothesis of a nutritional origin of the systemic granulomatosis.  相似文献   

15.
The purpose of this study was to evaluate the effect of varying dietary levels of highly unsaturated fatty acids (HUFAs) in live prey (Artemia nauplii and a calanoid copepod, Schmackeria dubia) on the growth performance, survival, and fatty acid composition of the lined seahorse, Hippocampus erectus, juveniles. Artemia nauplii were enriched with a commercial product (SS? 50DE‐microcapsule as HUFA source, 2/3 DHA, 1/3 EPA. Shengsuo Fishery Feed Research Center of Shandong Province, Qingdao, China) at four concentrations of 0.0, 14.0, 28.0, and 56.0. Newly hatched juveniles were cultured for 35 days. The content of docosahexaenoic acid (DHA), eicosapentaenoic acid (EPA), and n‐3 HUFAs in the Artemia nauplii was positively related to the enrichment concentration. At the end of the trials, growth performance of the juveniles was positively related to the enrichment concentration as well. However, the juveniles fed prey enriched with the highest concentration of enrichment (56.0 μL/L) had the significantly lower (P < 0.05) survival rate. The juveniles fed the copepod had the best growth performance and the highest survival rate, suggesting that the copepod, S. dubia, is suitable for feeding the seahorse juveniles. The comparisons between the growth, survival, and fatty acid profiles of the juveniles fed Artemia and copepods indicate that the seahorse juveniles require dietary levels of DHA beyond those achieved by enriching prey with the HUFA enrichment. Surplus EPA resulted from an imbalance between DHA and EPA in the enriched Artemia nauplii probably caused an adverse effect on the seahorse juveniles. This study suggests that DHA and EPA requirement of the lined seahorse juveniles is roughly 32% of total fatty acid, and the optimal DHA/EPA ratio for the species is circa 4:1. To avoid an adverse effect resulting from excessive EPA, maximum proportion of EPA in enriched Artemia nauplii should not exceed 13% of total fatty acid, and a recommended minimum DHA/EPA ratio in the enriched Artemia nauplii is 1.46. Arachidonic acid (20:4n‐6) might not be an essential fatty acid for the seahorse juveniles.  相似文献   

16.
Using microalgae for animal nutrition provides an economically viable route for microalgae‐based technological innovation, especially in combination with CO2 fixation given current global warming. However, this technology still lacks sufficient evaluation for screening microalgae for specific animals; meanwhile, current studies show some prejudice regarding ‘essential’ or ‘non‐essential’ ingredients. The results show that Dunaliella salina and Nannochloropsis salina were able to accumulate high protein (30%–57%) and lipid (20%–46%) content without affecting the performance of CO2 fixation, which reached 0.28 and 0.23 g L?1 day?1 respectively. Both species exhibited high quality of lipids and proteins for Penaeus monodon based on the profiling. The essential fatty acid indexes (EFAI) for N. salina and D. salina were 3.81 and 9.02 respectively. Butyric acid was found to be present in both D. salina (12.03%) and N. salina (4.87%) based on the total fatty acids (FAs). The essential amino acid indexes (EAAI) for D. salina and N. salina were 2.23 and 1.29 respectively. Arginine was the most abundant essential amino acid (EAA) in both D. salina (10.83%) and N. salina (13.35%) on the basis of total amino acids (AAs). This study comprehensively compares the nutritional quality of the two commercial marine microalgae of D. salina and N. salina with the potential to be used as sustainable sources of lipids and proteins to reduce or even replace the traditional fish oil and fish meal in aquafeeds.  相似文献   

17.
The present study aimed to evaluate the effect of the supplementation of different crab zoeas to enriched Artemia basal diet for Octopus vulgaris paralarvae during the first month of life. Paralarvae were fed using enriched Artemia nauplii alone and Artemia co‐fed either first zoea stages of Grapsus adscensionis or Plagusia depressa. The experiment was carried out over a period of 28 days, in 0.12 m3 tanks with a flow‐through rearing system. Growth in dry weight as well as mantle length and width were assessed weekly. Additionally, prey and paralarvae fatty acid composition and digestive gland (DG) histology were evaluated. Addition of low amounts of crab zoeas (approx. 100 indv. L?1 day?1) provided during critical life stages of O. vulgaris proved to be good enough to improve paralarvae growth and survival in comparison with those fed exclusively on enriched Artemia. These results were supported by the finding of a higher number of glycoprotein absorption vacuoles in the DG from paralarvae co‐fed crab zoeas, suggesting a higher feeding activity. In addition, fatty acid analysis of crab zoea showed that these are good sources of dietary arachidonic and eicosapentaenoic acids during the octopus planktonic life stage, whereas the low docosahexaenoic (DHA) content suggests the use of additional DHA sources or higher zoea densities to meet paralarvae nutritional demand to carry out a successful metamorphosis to benthic life.  相似文献   

18.
This investigation examined the effects on growth and survival of seahorses Hippocampus abdominalis Leeson 1827 fed a 25% body weight (wet weight) daily ration of live Artemia sp. enriched with Algamac‐3050, frozen mysids Amblyops kempi or a combination of live enriched Artemia and frozen mysids. After 3 months there was no difference in seahorse length, wet weight, condition factor (CF), or food conversion ratios (FCR) between the treatments. Mean daily specific growth rate (SGR) was higher for the Artemia‐only treatment than for the mysid‐only treatment (P<0.05). FCRs ranged from 6.14 g to 8.72 g dry weight of food required to give a 1‐g dry weight increase in seahorses. There was no difference in survival between treatments. Fatty acid analysis revealed that mysids had a higher percentage composition of EPA, 20 : 5n‐3, and DHA, 22 : 6n‐3, but a lower composition of AA, 20 : 4n‐6, than enriched Artemia. Percentage n‐3 highly unsaturated fatty acids (HUFAs) in mysid levels were approximately twice that of Artemia. Proximate analysis revealed mysids to be higher than the enriched Artemia in protein and fats, and lower in water content. This experiment demonstrates that, although no growth advantage was derived from the use of frozen mysids, they can be used successfully as an alternative food to live enriched Artemia for H. abdominalis. The use of frozen mysids is highly recommended in commercial seahorse culture if the seahorses are to be sold into the live aquarium trade, as this may increase their chances of survival after sale.  相似文献   

19.
Green water is a technique commonly used in aquaculture, that consists of adding live algae in the water culture and its benefits have been shown for several species. Several hypotheses exist to explain the benefits of green water: increase in nutritional value; action as a probiotic; increase in contrast to reveal preys for larvae; or increase in predator behaviour of larvae. Green water produced with a mix of strains Isochrysis galbana and Chaetoceros muelleri (50:50, cells:cells) applied in four different ways was tested. The survival and the growth of American lobster (Homarus americanus) between stage I and stage IV post‐larvae were not affected by the addition of live algae. The lipid classes were not affected by the addition of algae and limited variation was observed in the fatty acids and bacterial profiles. Furthermore, the green water techniques had a limited effect on the behaviour of post‐larvae stage IV lobster at releasing. Behaviour was mostly affected by the age of post‐larvae. The bacteria Lewinella sp., Leucothrix sp. and Thiothrix sp. appeared to represent a common and core component of Stage IV lobster post‐larvae microflora. The results show that the algae do not increase either nutritional value or feed intake of the lobster larvae. Probiotic effect may be more important when larvae are raised in a close system where potential bacterial pathogens could have more chances to colonize the culture. Also, the dark green colour of the larval tank used in this study may have mimicked the effect of green water in the control group. Biochemical results suggest that dietary supplementation with phospholipids and DHA is needed in a lobster hatchery using frozen Artemia and our open formula Dry mix.  相似文献   

20.
To study the effect of dietary supplementation of iodine in Solea senegalensis, larvae were randomly distributed in six tanks. Larvae in three tanks were given rotifers and Artemia enriched with iodine in addition to Rich Advance or Super Selco from 2 days after hatch (DAH) until 31 DAH. Larvae in a second set of three tanks were fed control rotifers and Artemia, enriched only with Rich Advance or Super Selco. Samples were collected at 2, 5, 10, 15 and 31 DAH to determine dry weight, total length, myotome height and thyroid status. Larvae fed the iodine‐enriched diet had significantly higher weight at 31 DAH and higher levels of whole body iodine concentration, compared to control larvae. At 31 DAH, larvae from the control treatment showed typical goitrous thyroid follicles. Thyroid cells of larvae from this treatment appeared columnar or afollicular, with the colloid partly or completely depleted, representative of hyperplasia (goitre). The lower growth rate in fish larvae from the control treatment was possibly a consequence of the hyperplasia, and the iodine enrichment prevented Senegalese sole larvae from developing goitre. This study demonstrates the importance of iodine enrichment of live feed for fish reared in a recirculation system.  相似文献   

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