Enrichment of Rotifers Brachionus plicatilis with Eicosapentaenoic Acid and Docosahexaenoic Acid Produced by Bacteria

Abstract— Two bacterial strains, rich in either eicosapentaenoic acid [EPA, 20:5(n-3)] ( Shewanella gel-idimarina ACAM 456) or docosahexaenoic acid [DHA, 22:6(n-3)] ( Colwellia psychroeryrhrus ACAM 605) were tested for their ability to enrich rotifers Erachionus plicatilis in these polyunsaturated fatty acids. Rotifers were exposed for 24 h to each bacterial strain and to a mixture of the two strains. They were then harvested and their fatty acid compositions were analysed and compared to those of rotifers that had been either starved or fed yeast Saccharomyces cerevisiae or microalgae Tetraselmis suecica in 2-L glass flasks. Exposure to 1.4 × 10⁹ cells/ml of the EPA-producing bacterium only resulted in rotifer EPA levels increasing from 0.1% to 1.2% of total dry weight (%dw). Similarly, following exposure to 1.0 × 10⁹ cells/mL of the DHA-producing bacterium only, rotifer DHA levels increased from below detection to 0.1% dw. When exposed to a mixture of the two bacterial strains, containing 7.0 × 10⁸ celldml of the EPA producer and 5.0 × 10⁸ cells/mL of the DHA producer, the rotifers'final EPA and DHA levels were 0.5% dw and 0.3% dw respectively. Although feeding strategies need refining, these results show, for the first time, that rotifers can be enriched with DHA from bacteria, and that rotifers can be enriched simultaneously with both DHA and EPA from different bacterial strains.     

Effects of yeast and algal diets on the growth and biochemical composition of the rotifer Brachionus plicatilis (Müller) in culture

Abstract. Growth rates and fecundity of Brachionus plicatilis fed baker's yeast, a diatom, and three different flagellates, were monitored during a 15-day feeding trial. Identical growing conditions and equivalent food levels for the different diets were maintained during rotifer culture. The highest growth rate and mean fecundity were exhibited by rotifers fed Chlorella saccharophila , followed in decreasing order by those fed Isochrysis galbana (T-iso), Tetraselmis suecica, Saccharomyces cerevisiae and Thalassiosira pseudonana . Significant differences in contents of neutral lipids, polar lipids, sugars, glycogen, protein, ash and corresponding energy reserves in the resultant five groups of rotifers were diet dependent. Total available energy, about 15 kJ/g in rotifers fed S. cerevisiae and I. galbana (T-iso) was significantly different from the 14kJ/g in rotifers fed T. suecica and C saccharophila, and in turn from the 13kJ/g in rotifers fed T. pseudonana .     

The enrichment and retention of ascorbic acid in rotifers fed microalgal diets

The enrichment and retention of ascorbic acid (AA) was investigated in rotifers Brachionus plicatilis fed on microalgae ( Nannochloropsis oculata and Isochrysis sp. (T.ISO)) and baker's yeast Saccharomyces cerevisiae . The concentrations of AA of the rotifer diets used in the study differed significantly: 4200 μg g⁻¹ of dry weight in Isochrysis sp. (T.ISO), 2600 μg g⁻¹ in N. oculata and only 77 μg g⁻¹ in S. cerevisiae . Rotifers contained 620 μg AA g⁻¹ prior to the experimental feeding. When subsequently fed for 3 h on microalgae at a ration of 0.13 mg dry microalgae per 10⁶ rotifers rapidly and efficiently increased their content of AA: Isochrysis sp.-fed rotifers contained 1600 μg AA g⁻¹ and N. oculata -fed rotifers contained 1100 μg AA g⁻¹. Concentrations were boosted by a further feeding of a second ration of algae at three times the initial feeding ration; 21 h later, Isochrysis sp.-fed rotifers contained 2500 μg AA g⁻¹ and N. oculata -fed rotifers contained 1700 μg AA g⁻¹. This represented a 180% and 310% increase in the pre-feeding vitamin concentrations in Isochrysis sp. and N. oculata -fed rotifers, respectively. There were no significant changes in AA concentration in rotifers fed a similar ration of yeast throughout the feeding period (520-620 μg AA g⁻¹). Rotifers retained AA during a subsequent 24 h non-feeding period, with no significant changes in the concentrations in any of the rotifer groups. The production of rotifers rich in AA may be particularly valuable for the culture of fish larvae that have a high requirement for the vitamin.     

Relationship between prey utilization and growth variation in hatchery‐reared Pacific bluefin tuna,Thunnus orientalis (Temminck et Schlegel), larvae estimated using nitrogen stable isotope analysis

In mass culture of Pacific bluefin tuna Thunnus orientalis, a marked growth variation is observed after they start feeding at 6–7 mm in body length (BL) on yolk‐sac larvae of other species, and the growth variation in tuna larvae is a factor leading to the prevalence of cannibalism. To examine the relationship between prey utilization and growth variation, nitrogen stable isotope ratios (δ¹⁵N) of individual larvae were analysed. A prey switch experiment was conducted under two different feeding regimes: a group fed rotifers (rotifer fed group), and a group fed yolk‐sac larvae of spangled emperor, Lethrinus nebulosus (fish fed group) from 15 days after hatching (6.87 mm BL). The fish fed group showed significantly higher growth than the rotifer fed group. Changes in the δ¹⁵N of the fish fed group were expressed as an exponential model and showed different patterns from those of the rotifer fed group. The δ¹⁵N of fast‐growing tuna larvae collected in an actual mass culture tank after the feeding of yolk‐sac larvae was significantly higher than those of the slow‐growing larvae, indicating that slow glowing larvae depended largely on rotifers rather than the yolk‐sac larvae.     

Effect of rotifer enrichment with herbal extracts on growth and resistance of red sea bream,Pagrus major (Temminck & Schlegel) larvae against Vibrio anguillarum

The effects of the dietary medicinal herbs Massa medicata, Crataegi fructus (Cf), Artemisia capillaries, Cnidium officinale and their mixture (HM), on growth and resistance against Vibrio anguillarum were examined using larval red sea bream, Pagrus major. The methanol extracts of Cf and HM inhibited the proliferation of seven infectious bacterial strains including the genera Aeromonas, Edwasiella, Photobavterium, Pseudomonas and Vibrio. Rotifers enriched with emulsified bonito oil containing extracts of Cf and HM lowered the bacterial counts in their body on TCBS medium for the genus Vibrio in comparison with rotifers enriched by emulsified bonito oil alone. Although statistically not significant, larvae fed rotifer fortified with Cf from 3 to 20 days after hatching showed the best growth and final body weight followed by those given rotifer with HM and control enrichment. However, final body length of larvae fed rotifer with Cf was significantly larger than larvae fed on rotifers enriched with other herb extracts. After a challenge test with V. anguillarum, survival of larvae fed rotifer with Cf and HM was significantly higher than for the control treatment. These results revealed that Cf and HM in rotifer is useful to promote growth and resistance against V. anguillarum in red sea bream larvae, providing a new technology for mass production of disease‐resistant fry and fingerlings.     

Aspects of the feeding biology of the copepod Pseudodiaptomus hessei (Copepoda: Calanoida) under culture conditions

This study aimed to investigate the feeding behaviour (particularly gut fullness and evacuation, preying on rotifers and feeding preference in the water column) of the calanoid copepod, Pseudodiaptomus hessei, as a potential live feed species for aquaculture. Fed and starved, male and female P. hessei were fed rotifers (Brachionus plicatilis) in the presence and absence of microalgae for 24 hr. Starved copepods consumed more rotifers (11.31 ± 1.01, individual rotifers) than fed (8.06 ± 1.01, individual rotifers) while the number of rotifers consumed in the presence of microalgae was similar when fed or starved. Gut fullness and evacuation was determined by feeding copepods two different cell size microalgae species (Tetraselmis suecica and Isochrysis galbana). Gut fullness and evacuation percentage were observed under the dissecting microscope (as 0, 25, 50, 75 and 100%). Copepods fed on T. suecica (large cell) filled their guts more rapidly, while those fed on I. galbana (small cell) evacuated their guts faster. Feeding preference was determined using a multifactorial experiment where copepods were fed two microalgae species, T. suecica and I. galbana, each presented as benthic and planktonic food sources. P. hessei preferred to feed on planktonic microalgae first regardless of microalgae choice species for ±80 min, before shifting to benthic food source. This information can be used as baseline information for aquaculturists to rear the species as live feed for marine fish larvae.     

Assessment of marine thraustochytrid <Emphasis Type="Italic">Schizochytrium limacinum</Emphasis> OUC88 for mariculture by enriched feeds

ABSTRACT:   In the present study, Schizochytrium limacinum OUC88, a thraustochytrid with high content of docosahexaenoic acid (DHA, 22:6 n −3), was used as feed for rotifer Brachionus plicatilis and Artemia franciscana . The rotifer and Artemia were harvested at 3, 6, 9, 12, 18, and 24-h intervals, analyzed for fatty acid composition, and compared with the control which fed on yeast only. The highest DHA content resulted from an enrichment period of 12 h for both fed organisms, reached 13.4 and 10.9% of the total fatty acids (TFAs) in rotifers and Artemia nauplii, respectively, and the DHA level reduced sharply if enrichment time was longer than 12 h. The pseudoalbinism rate of turbot Scophthalmus maximus juveniles fed enriched rotifers and Artemia nauplii reduced greatly (40% lower than in control group). Thus, enrichment of rotifers and Artemia nauplii by DHA-rich Schizochytrium limacinum OUC88 may provide a practical strategy for feeding fish juveniles in aquaculture.     

Effect of feeding rotifers enriched with taurine on the growth and survival of larval amberjack Seriola dumerili

The effect of feeding rotifers enriched with taurine on the growth performance and survival of larval amberjack Seriola dumerili was investigated. Rotifers were enriched with a commercial taurine supplement at four levels (0, 200, 400, and 800 mg/l). The larvae were fed the enriched rotifers in triplicate from 3 days post-hatch for 7 days under static conditions. The average taurine contents of the rotifers were 1.5, 2.7, 4.2, and 7.2 mg/g dry matter, respectively. The growth of the fish fed rotifers enriched with the taurine supplement at 800 mg/l was significantly (P < 0.05) improved compared with that of the fish fed the rotifers without taurine enrichment. The survival rate improved proportionally up to a taurine supplement level of 400 mg/l, but no significant differences in survival were observed among treatments. The fraction of the larvae with inflated swim bladders did not vary significantly between treatments. Taurine content in the whole fish body increased with the taurine level in the rotifers. These results suggest that taurine enrichment of rotifers is an effective method of enhancing the growth of amberjack larvae.     

Rotifers fed various diets of baker''s yeast and/or Nannochloropsis oculata and their effect on the growth and survival of striped mullet (Mugil cephalus) and milkfish (Chanos chanos) larvae

The rotifer Brachionus plicatilis (S-type Hawaiian strain) was cultured with various combinations of baker's yeast and Nannochloropsis oculata. There were no significant differences in the daily rotifer production and amino acid profiles of the resulting rotifers. The significantly lower levels of fatty acids (C14, C16, C20:4n−6, C20:5n−3 and C22:6n−3) observed in the rotifers were found to correspond with the amount of yeast presented in their diet. The low survival and growth of striped mullet larvae recorded at Day 15 posthatching indicates that rotifers fed only yeast were nutritionally deficient in fatty acids. The fatty acid requirements of mullet, however, appeared to be satisfied with rotifers cultured on a combination of yeast and N. oculata. In contrast, no significant differences in larval milkfish survival and growth at Day 10 posthatching were detected when using rotifers fed the various diets in the larval rearing protocol.     

Bacterial colonization of winter flounder Pseudopleuronectes americanus fed live feed enriched with three different commercial diets

The proliferation of bacteria in intensive aquaculture systems may be responsible for poor growth and mass mortality of marine fish larvae. Essential fatty acids provided in the diet could protect larvae by modulation of the immune response via arachidonic acid (AA) and eicosapentaenoic acid (EPA). Winter flounder Pseudopleuronectes americanus larvae were fed rotifers Brachionus plicatilis enriched with three commercial diets containing different fatty acid profiles. Bacterial colonization on the gills and skin and in the intestinal lumen was evaluated at the end of the rotifer feeding period (day 26), and growth was surveyed until metamorphosis. At 26 days post hatching, larvae fed rotifers containing the higher AA content and with a higher docosahexaenoic acid (DHA) to EPA ratio showed better growth and the lowest bacterial colonization of the intestinal lumen compared to larvae fed rotifers with the lowest AA and DHA : EPA levels. AA had been selectively incorporated into the polar lipids of larvae fed the rotifers enriched with the three diets. This is the first study in winter flounder larvae to report a link between different commercial rotifer enrichments and bacterial density in intestinal lumen.     

Biochemical composition and fatty acid profile in a strain of the lineage ‘Nevada’, belonging to the Brachionus plicatilis (Rotifera) complex,fed different diets

A strain of the lineage Brachionus ‘Nevada’ was batch cultured with two diets, differing in biochemical composition: baker's yeast (treatment 1), which has higher protein:lipid ratio compared with CULTURE SELCO (treatment 2). The biochemical composition (DNA, RNA, lipid, protein content) and fatty acid profile of rotifers of both treatments was analysed and related to previously published population structure data. CULTURE SELCO‐fed rotifers showed higher DNA, RNA, lipid, n‐3 highly unsaturated fatty acids (HUFA) average content, compared with yeast‐fed rotifers, which had higher protein content. Rotifer lipid content showed significant diurnal variation in yeast‐fed rotifers. Rotifer lipid and n‐3 HUFA content was associated with reproductive output. DNA and RNA content was related to embryonic development while protein content, to somatic growth and mixis. The saturated and monounsaturated fatty acid rotifer content was stable irrespective of feed, in contrast to eicosapentanoic acid (EPA) and DHA. The levels of AA were similar in both rotifer populations, but those of EPA and docosahexaenoic acid (DHA) were about half in yeast‐fed compared with CULTURE SELCO‐fed rotifers. CULTURE SELCO resulted in a temporally stable rotifer lipid profile and a better enriched parthenogenetic population.     

Partial decontamination of rotifers with ultraviolet radiation: the effect of changes in the bacterial load and flora of rotifers on mortalities in start-feeding larval turbot

Exposure of the rotifer Brachionus plicatilis to ultraviolet radiation in 1 mm deep liquid layers at an energy intensity of 38 mW cm⁻² reduced the rotifer bacterial load by >90% within 2 min. Such radiation doses had no significant effect upon rotifer viability, fatty acid composition, swimming or feeding activity. The surviving bacterial flora of irradiated rotifers was similar to that of un-irradiated rotifers and there was no evidence of major differences in sensitivity to ultraviolet radiation between different bacteria. For irradiation of large numbers of rotifers, a flow-through cell was used, operated with rotifer densities of 200 ml⁻¹ and a flow rate of 1.5 l min⁻¹. In two separate field trials involving groups of 34,000 turbot larvae per group, higher survival was found in groups receiving ultraviolet-irradiated rotifers in which the bacterial load was reduced by 88%. This was attributed to the slower rate of colonisation of the larval gut by bacteria, as a consequence of the lower bacterial load on the rotifers. Attempts to introduce specified bacteria into the larval turbot gut in significant numbers by colonisation of either normal or irradiated rotifers with particular bacteria were unsuccessful.     

锯缘青蟹幼体饵料的营养强化

用酵母、水球藻、鱼油强化和豆油强化四种不同方式培养轮虫，再分别投喂锯缘青蟹幼体，分析测定轮虫和体的生化组成，结果显示，（1）不同方式培养的轮虫之间以及摄食这些轮虫的锯缘青蟹幼体之间的蛋白质含量都没有显著差异；（2）轮虫的脂类含量和脂肪酸组成与培养方式密切相关，小球藻轮虫的脂类含量最高，20：5n-3(EPA)占总脂肪酸的比例也最高 ，为18.05%，鱼油轮虫则含有最多的22：6n-3(DHA)，占总脂肪酸3.16%，脂类含量仅次于小球藻轮虫；（3）锯缘青蟹幼体的脂类含量和脂肪酸组成受相应饵料营养成分的影响。另外，幼体培育实验也发现，饵料营养成分影响幼体的存活率，结果表明，提高轮虫的EPA和DHA含量，尤其晨DHA含量，将有利于锯缘青蟹幼体的存活和发育。     

Effects of docosahexaenoic acid on growth,survival and swim bladder inflation of larval amberjack ( Seriola dumerili, Risso)

The effect of docosahexaenoic acid (DHA) on the growth performance, survival and swim bladder inflation of larval Seriola dumerili during the rotifer feeding period was investigated in two feeding experiments. Amberjack larvae at 3 day post hatching were fed rotifers enriched with (1) freshwater C hlorella (Chlo), (2) a mixture (2:1, v/v) of Chlo and DHA‐enriched C hlorella (DHA‐Chlo), (3) DHA‐Chlo and (4) DHA‐Chlo and commercial DHA emulsion, in triplicate for 7 days. The average DHA contents of the rotifers were 0.0, 0.4, 1.0 and 1.9 mg g^?1 DM respectively. The survival rate was improved by the enrichment of rotifers with DHA‐Chlo alone, and DHA‐Chlo and emulsion. Growth and swim bladder inflation of fish fed rotifers enriched with DHA‐Chlo were significantly (P < 0.05) improved, however, with increased levels of DHA further improvement was not found. DHA content in the larval whole body proportionally increased with the DHA level in the rotifers. These results suggest that DHA enrichment of rotifers is effective to improve the growth, survival rate and swim bladder inflation of amberjack larvae. The DHA requirement of amberjack larvae is estimated to be 1.5 mg g^?1 on a dry matter basis of rotifers.     

The effect of light intensity on first feeding of the spotted sand bass Paralabrax maculatofasciatus (Steindachner) larvae

The effects of light intensity on feeding incidence and prey consumption at first feeding of spotted sand bass larvae (Paralabrax maculatofasciatus Steindachner), using four light intensity treatments (0, 100, 400, and 700 lx) were evaluated. Specimens were fed the rotifer Brachionus plicatilis at a density of 3 rotifers mL^?1. One hour after the addition of prey, 30±3 (mean±SEM) larvae were sampled from each treatment aquarium. Feeding incidence was evaluated as the percentage of larvae with prey in the digestive tract. Feeding intensity was measured as the number of prey in the digestive tract of the larvae. Histological analysis was carried out to describe the eye structure at the time of first feeding. Larvae fed in darkness (0 lx) had a significantly lower (P<0.05) feeding incidence (1.2±2.2%) and intensity (0.4±0.7 rotifers larvae^?1) than those larvae fed at 100 (28±11%, 1.8±0.2 rotifers larvae^?1), 400 (48±10%, 2.4±0.3 rotifers larvae^?1), and 700 lx (52±4%, 2.4±0.1 rotifers larvae^?1). Feeding incidence of the spotted sand bass larvae increased with light intensity while the feeding intensity showed no significant difference (P>0.05) between light treatments. Histological analysis of the eye structure showed that first feeding larvae had well‐formed lens along with a retina composed of pure single cones as photoreceptors.     

Waste‐grown phototrophic bacterium supports culture of the rotifer,Brachionus rotundiformis

The present and commonly used batch culture system (BCS) as adopted by many small‐scale tropical hatcheries is beset by poor rotifer production and sudden crashes. This study aimed to produce nutritive rotifers and evaluate their performance based on the BCS by using phototrophic bacteria (PB) that can be easily and cheaply cultured from palm oil mill effluent (POME), an agro‐industrial byproduct usually discarded as waste. Brachionus rotundiformis given a sole diet of POME‐grown PB (Rhodovulum sulfidophilum) grew as well as on the commercially produced microalgae, Nannochloropsis. Production, growth rate and fecundity of rotifers fed condensed bacterial cells (bPB) and culture broth of bacteria grown in POME (cPB) were evaluated. The best performance in terms of the stated parameters was obtained for rotifers fed 200 mL of cPB in 3 L of culture water; this media sustained a mean rotifer density of 600–900 individuals mL^?1 after 3–6 days of culture. The biochemical composition of rotifers fed PB was comparable to those fed microalgae, except that the former contained more polyunsaturated fatty acids.     

The effect of different rotifer feeding regimes on the growth and survival of yellowtail kingfish Seriola lalandi (Valenciennes, 1833) larvae

First feeding success is critical to larval marine finfish and optimization of live feed densities is important for larval performance and the economics of commercial hatchery production. This study investigated various rotifer feeding regimes on the prey consumption, growth and survival of yellowtail kingfish Seriola lalandi larvae over the first 12 days post hatch (dph). The common practice of maintaining high densities of rotifers (10–30 ind. mL^?1) in the rearing tank was compared to a low density feeding technique, where 5–8 ind. mL^?1 of rotifers were offered. A ‘hybrid’ feeding regime offered rotifers at the high density treatment until 5 dph and the lower feeding densities thereafter. There was no significant difference in larval survival (hybrid: 28.9 ± 7%, low density: 17.3 ± 5% and high density: 17.2 ± 9%) or growth (hybrid: 6.12 ± 0.18 mm, low density: 6.03 ± 0.10 mm and high density: 6.11 ± 0.23 mm) between treatments. Rotifer ingestion was independent of rotifer density throughout the trial and increased with larval age, with larvae at 4 dph ingesting 22 ± 1.5 rotifers larvae^?1 h^?1 and by 11 dph ingesting 59 ± 1.6 rotifers larvae^?1 h^?1. These data demonstrate that from first feeding, yellowtail kingfish larvae are efficient at capturing prey at the densities presented here and consequently significant savings in rotifer production costs as well as other potential benefits such as facilitation of early weaning and improved rotifer nutritional value may be obtained by utilizing lower density rotifer feeding regimes.     

Effect of combination feeding of <Emphasis Type="Italic">Nannochloropsis</Emphasis> and freshwater <Emphasis Type="Italic">Chlorella</Emphasis> on the fatty acid composition of rotifer <Emphasis Type="Italic">Brachionus plicatilis</Emphasis> in a continuous culture

ABSTRACT:   A continuous culture of rotifer was conducted to investigate the effect of combination feeding of both a high density of Nannochloropsis oculata (N) and condensed freshwater Chlorella (FC) on the fatty acid composition of L-type rotifer Brachionus plicatilis in a continuous culture system. The algal feeding of the rotifers was carried out in three successive steps: N-feeding → N+FC-feeding → FC-feeding. The culture was conducted at 24°C and 25–27 psu in a 2000 mL bottle with 50% of water exchanged daily. The combination N+FC-feeding was effective in increasing rotifer density. The rotifers fed on N+FC (N+FC-R) had more non-polar lipids than polar ones, similar to those on N (N-R), opposite to the rotifers fed on FC (FC-R). N+FC-R contained higher levels of 16:2, 18:2n-6 (linoleic acid [LA]) and 20:2n-6, but lower levels of 18:1, 20:4n-6 (arachidonic acid), 20:5n-3 (eicosapentaenoic acid [EPA]) and 22:5n-3 (docosapentaenoic acid [DPA]) compared with N-R. Whereas N+FC-R contained higher levels of 16:1n-7, EPA and DPA, but lower levels of 16:2 and LA compared with FC-R. N+FC-R had more DPA in polar lipids than in non-polar ones. The Σn-6/Σn-3 ratio in N+FC-R was 0.9–1.0, significantly different from those in N-R (0.4) and FC-R (6.6–8.4). Therefore, it is inferred that the fatty acid profile of the N+FC-R cultured in a continuous culture system was affected by both N and FC. Also, the combination N+FC-feeding may be effective in manipulating the Σn-6/Σn-3 ratio in continuously cultured rotifers.     

Replacement of fresh algae with commercial formulas to enrich rotifers in larval rearing of yellowtail kingfish Seriola lalandi (Valenciennes, 1833)

This study compared the efficacy of four products that are commonly used in hatchery for nutritional enhancement of rotifer Brachionus plicatilis as the starter food for yellowtail kingfish Seriola lalandi larvae. This experiment consisted of one fresh algae and three enrichment products: (1) Fresh algae were a mixture of Nannochloropsis and Isochrysis at 2:1 on a cell concentration basis; (2) S.presso, (Selco S.presso ^®, INVE Aquaculture); (3) Algamac 3050^® (Aquafauna, USA); (4) Nutrokol ^® (Nutra‐Kol, Australia). Survival rates of the fish fed rotifers enriched with fresh microalgae (40.69%) and S.presso (31.21%) were higher than those fed Algamac 3050 (10.31%). On 3 day post hatch (DPH), fish feeding incidence in the fresh algae treatment was significantly higher than that in other treatments. On 6 DPH, fish showed the lowest feeding incidence in the Algamac 3050 treatment. The methods of enrichment did not affect total lipid levels in either rotifer or fish larvae, but Algamac 3050 enrichment achieved the highest DHA/EPA ratio and lowest EPA/ARA ratio in both rotifers and fish larvae. This study indicates that fresh algae can be replaced by S.presso, but Algamac 3050 is not as good as other formula for rotifer enrichment in rearing yellowtail kingfish larvae in this system.     

几种单胞藻对褶皱臂尾轮虫的营养强化研究

利用气相色谱法测定了小球藻、牟氏角毛藻、球等鞭金藻和投喂不同藻类后12h的褶皱臂尾轮虫的脂肪酸含量。试验结果表明,不论是投喂单种藻类还是2种混合藻类,强化后的轮虫其体内的脂肪酸含量均发生了明显变化,其中单链脂肪酸及低度不饱和脂肪酸的含量在投喂前后没有变化,各种脂肪酸的含量界于未强化的轮虫和所投喂的单胞藻饵料含量之间。3种高度不饱和脂肪酸的含量,除了二十二碳六烯酸因在牟氏角毛藻中含量较低,在单独投喂牟氏角毛藻后的轮虫中未检测出外,其余均与其所投喂的单胞藻的脂肪酸一致;轮虫中被检出的3种高度不饱和脂肪酸的含量,在单种藻类试验组中均低于所投喂藻类的含量;在2种藻类混合试验组中界于2种单胞藻含量之间。混合藻类比单种藻类强化轮虫具有更加全面的营养效果。