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1.
Several commercial oils of plant and animal origin were tested in order to improve the HUFA content and the DHA:EPA ratio of Artemia sp. metanauplii. The relationship between the n-3 and n-6 fatty acid series, and more recently, the DHA:EPA ratio seem to be indicators for better survival and growth of marine fish larvae. The tested plant oils were derived from linseed, peanut and sunflower, and the animal oils came from squid, sardine, cod liver and Selco emulsion. For each oil emulsion tested, four different enrichment periods (9, 24, 33 and 48 h) were evaluated in the same Artemia sp. strain (Artemia EG from Artemia Systems Inc., Baasrode, Belgium). The results show that oil emulsions of plant origin give very poor results in relation to either HUFA content or DHA:EPA ratio. All the oil emulsions from animal origin resulted in HUFA incorporation. Sardine oil was the poorest and squid oil the best. The HUFA content and the DHA:EPA ratio increased with enrichment periods up to 33 h, followed by a negligible variation up to the final 48 h.  相似文献   

2.
An 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.  相似文献   

3.
ABSTRACT:   By conducing organoleptic analysis, the authors investigated the effect of oil droplet size on human preference to the taste of oil-in-water (o/w) emulsions to which several tastants were added. Two singly dispersed o/w emulsions, different in oil droplet sizes, consisting of 10% triacilglycerol purified from tuna, sardine or soybean oil, 0.5% emulsifier and water were prepared by ceramic membrane filtration. Organoleptic analysis showed that the impressions of sweetness, bitterness and umami, which were developed by addition of certain taste substances, were different between o/w emulsions with different oil droplet sizes. The results of two-bottle choice tests, which were carried out using olfactory-blocked mice, showed that o/w emulsions with 1.00-µm droplets, with added sweet or bitter substances, were preferred to emulsion with 5.50-µm droplets. These results suggest that the droplet size of o/w emulsion remarkably influences certain taste impressions created by added taste substances.  相似文献   

4.
采用乳化油直接添加法,用n－3高度不饱和脂肪酸（n－3HUFA）含量不等的4种乳化油分别强化轮虫、卤虫活饵料,培育4组黑鲷仔鱼和稚鱼,各自历时15d,结果表明,n－3HUFA对黑鲷仔鱼和稚鱼的生长和存活均有重要影响。在该条件下,轮虫体内n－3HUFA含量为0．233％（湿重计）,卤虫体内n－3HUFA含量为4．273％（湿重计）时,仔鱼和稚鱼达到最佳生长和成活率。  相似文献   

5.
Abstract. An investigation was conducted under laboratory conditions to determine the optimum food particle size of an inert diet for common carp fry ranging in size from 15 to 466mg body weight and 13 to 31 mm total length (TL). Speed of consumption of a standard quantity of food was used as a measurement of feeding preference/efficiency for different particle size ranges. It was observed that for carp of this size range preferred food particle size increases with fish size. On the basis of ingestion time and feeding behaviour, food particle sizes in the ranges 125-300μm. 300-500μm, 300-790μm and 500-1000μm diameter were found to be most appropriate for carp fry weighing 15-23mg(TL 13-18), 46-97 mg(TL 17-22), 105-209 mg (TL 20-25) and 210-466mg (TL 24-31) respectively. This study also demonstrated that for carp fry of these size ranges the mean preferred food particle sizes are about 02-04 that of mouth size. Based on this relationship, general recommendations are made on the optimum food particle sizes for different size classes of carp fry reared under hatchery and nursery conditions.  相似文献   

6.
The effect of varying levels of dietary n-3 highly unsaturated fatty acid (HUFA) and docosahexaenoic acid/eicosapentaenoic acid (DHA/EPA) ratios on growth, survival and osmotic stress tolerance of Eriocheir sinensis zoea larvae was studied in two separate experiments. In experiment I, larvae were fed rotifers and Artemia enriched with ICES emulsions with 0, 30 and 50% total n-3 HUFA levels but with the same DHA/EPA ratio of 0.6. In experiment II, larvae were fed different combinations of enriched rotifers and Artemia, in which, rotifers were enriched with emulsions containing 30% total n-3 HUFA, but different DHA/EPA ratio of 0.6, 2 and 4; while Artemia were enriched with the same emulsions, but DHA/EPA ratio of 0.6 and 4. In both experiments, un-enriched rotifers cultured on baker's yeast and newly-hatched Artemia nauplii were used as control diets. Larvae were fed rotifers at zoea 1 and zoea 2 stages; upon reaching zoea 3 stage, Artemia was introduced.Experiment I revealed no significant effect of prey enrichment on the survival of megalopa among treatments, but higher total n-3 HUFA levels significantly enhanced larval development (larval stage index, LSI) and resulted in higher individual dry body weight of megalopa. Furthermore higher dietary n-3 HUFA levels also resulted in better tolerance to salinity stress. Experiment II indicated that at the same total n-3 HUFA level, larvae continuously receiving a low dietary DHA/EPA ratio had significantly lower survival at the megalopa stage and inferior individual body weight at the megalopa stage, but no negative effect was observed on larval development (LSI). The ability to endure salinity stress of zoea 3, zoea 5 and megalopa fed diets with higher DHA/EPA ratio was also improved.  相似文献   

7.
A 44-day rearing trial was conducted to examine the enrichment of Artemia urmiana nauplii with vitamin E and highly unsaturated fatty acid (HUFA) and its effects on the growth performance, survival and stress resistance of great sturgeon, Huso huso , larvae. Cod liver oil (EPA 18% and DHA 12%) and α-tocopherol acetate were used as lipid and vitamin E sources. Beluga larvae at the first exogenous feeding with 69±5.9 mg body weight were randomly distributed into four treatments and three tanks were assigned to each diet. The test treatments were as follows: larvae fed with HUFA+20% and HUFA+50% (w/w) vitamin E-enriched Artemia nauplii (E1 and E2 groups, respectively), HUFA without vitamin E (HUFA group) and non-enriched Artemia (control group). All treatments fed non-enriched Artemia for the initial 5 days after first feeding and then fed enriched Artemia for 7 days. After the period of enrichment, larvae were fed with daphnia from the 13th to the 40th day. At day 40, submersion in salt water (6 ppt for 4 days and 12 ppt for 2 days) and warm water (33 °C for 2 days) was performed to evaluate larvae resistance to salinity and temperature stress. Final weight, daily growth rate, specific growth rate and weight gain were higher in beluga fed with enriched Artemia . The highest growth rates were observed in E1, whereas survival was not significantly different between groups. Use of vitamin E and HUFA significantly increased fish resistance to a salinity of 12 ppt and the lowest stress resistance was observed in the control group. Stress tolerance was not significantly different at 6 ppt and 33 °C between groups. There was no comparable difference in the haematocrit index under stress conditions. These results indicated that the enrichment of Artemia with essential fatty acids and vitamin E can affect some growth and stress tolerance factors in great sturgeon, Huso huso , larvae.  相似文献   

8.
Oil-seawater emulsions of 12%, 8%, 4% and 2% soya phosphatidylcholine (PC) in tuna orbital oil (TOO) (w:w) were tested with respect to their suitability as Artemia enrichment media. Levels of essential fatty acids (EFA) accumulated by feeding Artemia nauplii were measured after enrichment periods of 0, 14, 18 and 20 h, and the stability of polyunsaturated fatty acids levels in the emulsions were also monitored throughout the enrichment process. Artemia enrichment efficiency in terms of %DHA (docosahexaenoic acid, 22:6w-3) and DHA:EPA (eicosapentaenoic acid, 20:5w-3) ratios were similar for all four types of emulsions (10-12% and 1.7-1.8, respectively). However, 8% and 12% soya PC/TOO emulsions yielded nauplii with slightly higher mean lipid contents than the other two treatments (235-243 and 217-229 mg lipid g-1 dry body weight, respectively). Stability of polyunsaturated fatty acids (PUFA) levels within the emulsions in seawater, and of DHA and EPA levels in particular, correlated with soya PC concentration. In 12% soya PC/TOO emulsions, PUFA levels remained high after 20 h enrichment whilst those in the 2% and 4% soya PC emulsions showed a marked reduction by 18 h enrichment time. It is suggested that soya PC may protect PUFA levels in the emulsions in a dose-dependent manner, probably by acting as an antioxidant. No significant improvement in Artemia total lipid content or DHA:EPA ratio occurred when enrichment was continued for longer than 18 h. When using this enrichment system, it is preferable, therefore, to employ the 12% soya PC/TOO emulsion and to terminate the enrichment process at 18 h, thus preventing the risk of PUFA levels deteriorating in the emulsion.  相似文献   

9.
ω_3HUFA对中华绒螯蟹幼体存活率及体脂肪酸组成的影响   总被引：13，自引：4，他引：13  
陈立侨 《水产学报》2000,24(5):448-452
分别以经海水小球藻、牟氏角毛藻和５０ＤＥ－Ｇ强化剂强化的轮虫投喂中华绒螯蟹早期幼体,至Ｚａｏ状Ⅲ期后改喂卤虫无节幼体,探讨了饵料ω－３系列高度不饱和脂肪酸对幼体发育和存活的影响。结果表明：小球藻轮虫组的幼体发育至第Ⅰ期幼蟹的存活率最高,为１２．００％,强化剂轮虫组和角毛藻轮虫组次之,分别为１０．６７％和９．６７％,而酵母轮虫组最低,仅为３．６７％;结合分析Ｚａｏ状Ⅴ期幼体脂肪酸组成可知,幼体发育至第Ⅰ期幼蟹的存活率与其总脂含量和ω－３ＨＵＦＡ含量密切相关,而Ｚａｏ状Ⅴ期幼体总脂含量与ω－３ＨＵＦＡ含量随饵料轮虫总脂和ω－３ＨＵＦＡ含量的增加而提高,表明早期幼体所摄取的ω－３ＨＵＦＡ对后期幼体发育和存活有明显的促进作用。  相似文献   

10.
Two experiments were carried out to investigate the effects of docosahexaenoic acid (DHA), eicosapentaenoic acid (EPA) and arachidonic acid (ARA) levels in rotifers (Brachionus plicatilis) and Artemia on the survival, development and metamorphosis of mud crab Scylla paramamosain larvae. Five different lipid emulsions, varying in the level of total n‐3 and n‐6 highly unsaturated fatty acids (HUFA), DHA, EPA and ARA were used to manipulate the fatty acid profile of the live food. Fatty acid profiles of the live food and crab larvae at zoea one, three and five stages were analysed to study the HUFA uptake by the larvae. The fatty acid content of the live food affected the fatty acid profiles of the crab larvae. In both experiments, the survival rate in the zoeal stages was not statistically different among treatments. However, larval development rate and metamorphosis success were affected by the dietary treatments. In this respect, the DHA/EPA ratio in the live food seems to be a key factor. Enrichment emulsions with a very high (50%) total HUFA content but a low DHA/EPA ratio (0.6), or zero total HUFA content caused developmental retardation and/or metamorphosis failure. An emulsion with a moderate total HUFA (30%) and a high DHA/EPA ratio (4) was the best in terms of larval development during the zoeal stages and resulted in improved metamorphosis. Dietary ARA seemed to improve first metamorphosis, but its exact role needs further clarification. For the larval rearing of S. paramamosain, an enrichment medium containing about 30% total n‐3 HUFA with a minimum DHA/EPA ratio of 1 is recommended. Further investigation is needed on the total HUFA and optimum DHA/EPA ratio requirements for each crab larval stage.  相似文献   

11.
The sessile suspension feeding ascidian, Styela clava , plays an important role in the functioning of estuarine systems. The feeding selectivity of S. clava was examined using standard physiological techniques in terms of particle sizes and diet concentrations. Styela clava increased its retention efficiency (the proportion of available particles retained in ascidian) with increasing particle size at a lower diet concentration [expressed as particulate organic matter (POM)] from 2.11 to 10.06 mg POM L−1, and the highest retention was reached for 5–20 μm particles. With increasing diet concentration to 20.12 mg POM L−1, S. clava retained small particles (<3.5 μm) more efficiently and large ones (>15 μm) less efficiently. The selectivity of ascidian with different sizes was similar at the same concentration. At every diet concentration, larger ascidians retained more 5–20 μm cells than the smaller ones. All these results indicate that S. clava possesses a particle selection mechanism that may affect the zooplankton communities to a certain degree.  相似文献   

12.
The combined effect of prefiltration and ultraviolet (UV) irradiation on the removal of bacteria associated with plankton fragments was investigated in an experimental flowthrough system. The system was supplied by sea water containing fragments of Artemia nauplii in the size range 10–240 μm diameter (mean = 66 μm), as determined by particle size analysis. By applying an UV dose of 10 mJ cm–2, the number of colony-forming units (CFU) was reduced from 7.4 × 105 per 100 mL to 2.0 × 103 per 100 mL. Increasing the dose to 13 or 22 mJ- cm–2 did not result in any further reduction, suggesting that bacteria associated with Artemia fragments were protected. This protection hypothesis was supported by improved overall bacterial removal efficiency by prefiltration. At the highest dose (22 mJ cm–2), more than 5 log10 units total reduction was obtained by prefiltration using 50-μm mesh sizes. The reductions relative to the unfiltered sample were 1.4, 2.4 and 3.0 log10 units using mesh sizes of 355, 80 and 50 μm respectively. It is concluded that sea water for aquacultural purposes should be filtered to remove particles before UV disinfection, thereby improving the overall bacterial removal efficiency and reducing the risk of introducing UV-shielded bacteria.  相似文献   

13.
Abstract.— Nutritional condition in larval fish culture has generally been evaluated based on growth and survival, and stress tolerance by air exposure. Here we made direct observations of fish in rearing tanks to estimate the quality of the fish. Pacific threadfin Polydactylu.s sexfilis larvae were reared with rotifers and Artemia nauplii enriched with three levels of highly unsaturated fatty acids (HUFA). The three levels were defined as no-, medium-, or high-HUFA groups, in which the fatty acids emulsions contained 0, 30, or 50%. respectively. of docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA). The formation of patchiness (dense aggregations of fish on the surface) and development of schooling behavior were observed in four replicate rearing tanks for each feed treatment. Patchiness was formed in every tank with the highest densities of 60–250 fish/L on day 7–8 posthatch. Both medium-HUFA and high-HUFA groups showed schooling behavior at 19 d after hatching, whereas fish in the no-HUFA group did not form schools even at day 25. The body lengths of fish from each group were not significantly different, although the no-HUFA group suffered high mortality after day 20. Our results suggest that HUFA deficiency has a serious negative impact on P. sexfilis during metamorphosis rather than during the early larval stage. We also consider that direct observation rather than stress tests by air exposure may be an effective tool to measure the quality of juvenile fish.  相似文献   

14.
Abstract. The effects of Artemia spp. and of Moina micrura from two culture sources, poultry manure and Chlorella supplemented with baker's yeast, on production of Macrobrachium rosenbergii (de Man) post-larvae (PL) were evaluated. Significantly higher production of 18·13 ± 1·45 PL/I was obtained for the larvae fed with 50:50 mixture of Artemia and Moina cultured on poultry manure compared to that for larvae fed Artemia alone (14·27 ± 1·64PL/I). Regardless of the culture source, the post-larval production was the lowest (9·23 ± 1·22 and 11·26 ± 1·33 PL/I for the larvae fed Moina. The higher dietary value of Moina cultured on poultry manure was related to the high content of n–3 HUFA particularly 20:5n-3 compared to Artemia and Moina cultured on Chlorella and yeast.  相似文献   

15.
In this study, the effect of edible coarse/nanoemulsions of alginate as coating containing Zataria multiflora Boiss essential oil (ZEO) on the microbial quality of fish fillets was investigated at three concentrations (i.e. 0.25%, 0.5% and 1% [w/v]) in 16 days of storage at 4°C. Moreover, a comparison was made between the fabricated coarse emulsion and nanoemulsion coatings by particle size and polydispersity index analyses. Sample analysis was performed with regard to total viable count (TVC), total psychrophilic count (TPC), hydrogen sulphide‐producing bacteria count (HSC) and Enterobacteriaceae count (ENC) on days 0, 4, 8, 12 and 16. According to the findings, all the samples showed increased microbial counts during the storage periods. The highest reduction rates of TVC (about 2 log CFU/g), TPC (about 1 log CFU/g), HSC (about 1.5 log CFU/g) and ENC (about 3 log CFU/g) were observed in the nanoemulsion of alginate containing 1% w/v ZEO (NE 1%) samples, compared with alginate and control samples. The microbial growth was significantly inhibited in all treatments, compared with that in the control (p < .05). Accordingly, it can be concluded that nanoemulsion coating was more effective than coarse emulsion to prolong the durability of fish fillets and revealed a faster and greater inhibition of microbial flora, compared with coarse emulsions during the storage time.  相似文献   

16.
This research reveals the applied engineering basis for determining the particle size and settling velocity distributions of solids generated while rearing wild-caught premature punctuated snake-eels (Ophichthus remiger) in a prototype recirculating aquacultural system. Settled solids were sampled from the bottom of the rearing tanks, and suspended solids were sampled before filtration within the drum filter and analyzed to characterize their settling velocity and particle size properties. These particle properties are considered bioengineering parameters since they will provide biological information to improve engineering solutions for RAS solids removal processes. The average settling velocity for the settleable solids in the rearing tanks was 2.89 ± 0.02 cm s−1, and the average particle size ranged between 7.32 ± 3.41 and 19.44 ± 8.58 mm. Suspended solids within the drum filters before filtration had an average settling velocity of 0.35 ± 0.11 cm s−1 and it was found that 69.93 % of the particles size was greater than 200 μm, 15.40 % were within the range of 120 μm and 90 μm sizes, and 6.53 % were between 70 μm and 40 μm sizes. The particle physical properties, settling curves, and particle sizes curves obtained from this experience represent valuable information to be used to improve engineering design of solids handling mechanisms, especially in marine land-based systems, and in this case, applied for rearing wild-caught punctuated snake-eels. The present investigation constitutes an advance in the knowledge of applied engineering to the design of a marine aquaculture fattening operation targeted to feed up wild-caught premature punctuated snake-eels to the point of sale or trade.  相似文献   

17.
Artemia salina cysts (San Francisco Bay Brand) were exposed in seawater containing multiple concentrations of either a single heavy metal (Hg, Cu, Zn, Pb, Cd, Co, Ni, Cr, Mn and Fe) or combination of heavy metals. The heavy metal accumulation in Artemia nauplii increased linearly with an increase in the heavy metal concentration in water. The metals could be detected in nauplii exposed to a single heavy metal at dosages of 5 μg/L for Hg, Zn, Mn, Fe and Cu; 25 μg/L for Cd and Cr; 50 μg/L for Co; 100 mUg/L for Ni; and 250 μg/L for Pb. Cysts exposed to several heavy metal combinations had minimum effective dosages equal to or lower than the single heavy metals- 5 μg/L for Cu, Cr, Zn, Mn and Fe; 25 μg/L for Cd and Ni; 50 μg/L for Co; and 250 μg/L for Pb. The accumulation of Cu, Ni and Co by Artemiu nauplii did not differ for animals exposed to single or combined heavy metal solutions. Cr, Zn and Pb had a synergistic effect of heavy metal uptake in combined heavy metal element solutions, however, Fe, Cd and Mn had an antagonistic effect.  相似文献   

18.
Abstract— The purpose of this study was to examine the effect of varying dietary levels of highly unsaturated fatty acids (HUFA) in Live prey on the standard length, specific growth rate, survival, and fatty acid composition of yellowtail snapper Ocyurus chrysurus larvae. Two experiments were conducted utilizing rotifers and Artemiu enriched with live algae ( Isochrysis galbana or Nannochloris oculata ) or commercial preparations (Aquagrow Advantage, Aquagrow Advantage plus Aquagrow arachidonic acid, and Algarnac 2000). Larval growth and fatty acid composition were evaluated during the rotifer, B rachionus plicatilis , and Artemia feeding periods and survival rates were calculated at the termination of each trial (18 or 20 d after hatching). In general, prey enriched with the commercial products contained higher levels of docosahexaenoic acid, eicosapentaenoic acid, n-3 HUFA, and × HUFA than those enriched with live algae. The addition of arachidonic acid to the Aquagrow Advantage enrichment medium significantly increased the amount of this fatty acid in rotifers but not in Artemia . At the end of the growth trials, larval standard length was highest when larvae were fed prey enriched with I. galbanu (6.4 mm) or commercial preparations (6.7–7.1 mm) versus N. oculatu (5.2 mm). Furthermore, larvae fed prey enriched with commercial preparations had significantly ( P < 0.05) higher survival rates (2.2-5.9%) than those fed prey enriched with live algae (1.1-1.4%). These results suggest that yellowtail snapper larvae require dietary levels of HUFA beyond those achieved by enriching prey with live N. oculata or I. galbana  相似文献   

19.
First‐feeding diets employed in the rearing of meagre (Argyrosomus regius) larvae are based on live preys that are commonly enriched to compensate for their deficiency of essential fatty acids. A feeding trial was conducted on meagre larvae (Argyrosomus regius) fed rotifer (Brachionus plicatilis) and Artemia salina enriched in lipids from an emulsion of cod liver oil (CLO) and a commercial product (CP). The effect of both enrichment products was evaluated on the survival rate, size and lipid composition of meagre larvae. The results showed that larvae fed CLO presented significant higher values of survival rate (35.0 ± 3.2%) and larval size (12.06 ± 1.17 mm) at the end of the experiment, compared to the CP diet (26.0 ± 2.5%, 11.41 ± 0.91 mm, respectively). Both zootechnical parameters were related to the content of polyunsaturated fatty acids in the larvae. Indeed, the larvae fed CLO presented a higher ratio DHA/EPA than those enriched in commercial product (0.82 ± 0.18 and 0.38 ± 0.12 at 26 days after hatching, respectively). Both larval groups presented similar body content of arachidonic acid (1.4 wt.% on average at 26 days after hatching), regardless the enrichment source. From all above, we can conclude that the enrichment of live preys with an emulsion of cod liver oil is an economically viable alternative to commercial products. Indeed, cod liver oil emulsions are able to fully meet the requirements for fatty acids of meagre larvae. Furthermore, cod liver oil is easily available from fish processing facilities.  相似文献   

20.
不同饵料对中华绒螯蟹幼体发育和存活的影响   总被引：15，自引：1，他引：15  
江洪波 《水产学报》2000,24(5):442-447
采用高度不饱和脂肪酸（ＨＵＦＡ）营养强化的轮虫、轮虫与卤虫组织投喂中华绒螯蟹幼体,以各项幼体的存活率为评判指标,对不同饵料及其组合的投喂效果进行了探讨。研究结果表明：轮虫是中华绒螯解早期幼体（Ⅰ、Ⅱ期）的适口饵料,幼体存活率随轮虫密度的增加而逐渐上升,但当轮虫数量超过最适密度时,幼体存活率反而有所下降。其中,未强化的轮虫达投喂密度为６０ｉｎｄ．ｍＬ＾－１,强化轮虫最适密度为４０ｉｎｄ．ｍＬ＾－１。Ｚａｏ状Ⅰ、Ⅱ期投喂４０ｉｎｄ．ｍＬ＾－１轮虫,从Ⅲ期开始投喂１０ｉｎｇ．ｍＬ＾－１卤虫无节幼体,能较好地满足中华绒螯蟹幼体发育的营养需求,提高大眼幼体的存活率。表明强化幼体饵料ＨＵＦＡ特别是ＥＰＡ和ＤＨＡ能有效地促进幼体的发育与存活和脱壳率。  相似文献   

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