首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献，搜索用时 31 毫秒
1.
The silver pomfret Pampus argenteus (Euphrasen) is a new candidate for aquaculture and there is not much information available on its larval rearing. Investigations carried out using microalgae alone in the culture system for the initial feeding of the silver pomfret larvae showed that Chlorella, Isochrysis and Nannochloropsis without rotifers are not conducive to the survival of newly hatched larvae. At 6 days after hatching (DAH), a maximum survival of 3% (1.8 ± 1.69%) was observed with Isochrysis followed by Nannochloropsis (0.35 ± 0.21%) and Chlorella (0.25 ± 0.21%). All control larvae died at 6 DAH without microalgae. Further investigations using the above microalgae with rotifers and a mixture of these same microalgae with rotifers showed that significantly higher (P < 0.05) survival could be achieved in the mixture of microalgae with rotifers in the culture system. At 12 DAH, the larval survival was 9.73 ± 1.39% in mixed species of algae compared with that of Isochrysis (6.93 ± 1.86%), Nannochloropsis (6.83 ± 0.61%), Chlorella (5.93 ± 2.76%) and seawater without microalgae or the control (0.73 ± 0.31%). The first incidence of feeding on rotifers at 4 DAH was significantly higher (P < 0.05) in all treatments with microalgae than that of the control. The incidence of feeding in mixed species of algae at 4 DAH (60.0 ± 0.00%) and in Isochrysis (55.0 ± 35.36%) was significantly higher (P < 0.05) than that of Chlorella (40.0 ± 0.00%) and the control (25.0 ± 7.07%). Prey consumption of individual larvae increased significantly (P < 0.01) at 8 DAH compared with that at 4 DAH. During this period, predation on rotifers by larvae was significantly higher (P < 0.05) in mixed species of algae (12.85 ± 5.73 rotifers larva?1) than that of the control (6.75 ± 1.20 rotifers larva?1). The fatty acid composition of rotifers used during this investigation shows that significantly higher (P < 0.05) ω3 HUFA was present in rotifers treated with mixed algae plus commercial enrichment media ‘Super Selco’ and ‘DHA Protein Selco’. Rearing of silver pomfret larvae up to the juvenile stage using mixed species of microalgae in the hatchery has been discussed. During 38 days of the larval rearing period, it was possible to achieve 3.6–4.2% larval survival with a mean of 3.9 ± 0.42%, which was considerably higher than in previous attempts (survival up to 1.5%).  相似文献   

2.
Early weaning of marine fish larvae with dry diets delays gut maturation and reduces growth rates. In juvenile and adult forms of several marine fish species, inclusion of dietary mannan oligosaccharides (MOS) improves gut integrity and functionality, but the effects of MOS inclusion in gilthead sea bream (Sparus aurata, L.) larval diets have not been addressed yet. Thus, this study assesses the effects of dietary MOS inclusion on survival, growth performance, gut morphology, feed acceptance and quality of gilthead sea bream larvae. For that purpose, 16 days post‐hatched gilthead sea bream larvae were fed four graded levels of MOS (Biomos®, Alltech, Nicholasville, KY, USA) in weaning diets as follows: 0 g kg?1 MOS, 0.5 g kg?1 MOS, 1.5 g kg?1 MOS and 2 g kg?1MOS. Dietary MOS did not affect feed acceptance in gilthead sea bream larvae (P > 0.05). MOS supplementation was correlated in a dose‐dependent way with higher larval survival (P = 0.026). After 15 days of feeding, dietary MOS increased whole larvae (P < 0.01) arachidonic acid, eicosapentaenoic acid and docosahexaenoic acid. Gilthead sea bream larvae fed 2 g kg?1 MOS presented higher gut occupation with goblet cells after feeding compared with larvae fed the other dietary treatments. Overall, the results suggest that inclusion of MOS in early weaning diets for gilthead sea bream improves essential fatty acid utilization and may promote growth and final survival.  相似文献   

3.
Pigfish (Orthopristis chrysoptera Linnaeus) are a commonly used baitfish in the southeastern United States. Aquaculture methods for broodfish spawning and juvenile grow‐out have been developed but there is still a paucity of information regarding larval culture methods. Five, short duration (10 days) experiments were conducted to determine effective strategies to yield high larval survival and growth during early development. Experiment one examined the rotifer enrichments Ori‐Green, DHA Protein Selco, and AlgaMac 3050 as well as a non‐enriched control along with corresponding fatty acid levels in the enriched rotifers and pigfish larvae. Experiment two evaluated three, once daily feeding frequencies of either 5, 10 or 20 rotifers mL?1. Experiment three compared feeding 20 rotifers mL?1 once daily to feeding 5 rotifers mL?1 twice daily. Experiment four examined four different larval stocking densities: 50, 75, 100, or 125 larvae L?1. Experiment five examined green water strategies using either live Tahitian strain Isochrysis galbana (Parke) or Nannochloropsis oculata (Hibberd) paste at either 250 000 or 500 000 cells mL?1 as well as a clear water control. Results indicated rotifer enrichment with DHA Protein Selco and green water application using live T‐ISO at 500 000 cells mL?1 had the highest survival of pigfish during early stages of larval culture. A once daily rotifer feeding regime of 20 rotifers mL?1 and stocking density of 50 larvae L?1 also improved survival. These results provide producers with methods to improve efficiency for pigfish larval culture and provide researchers with new foundational data, such as potential fatty acid requirements.  相似文献   

4.
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   

5.
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   

6.
Considering the well‐known problems arising from the use of rotifers and Artemia as live prey in larval rearing in terms of fatty acid deficiencies, the aim of this study was to evaluate a partial or complete replacement of traditional live prey with preserved copepods during the larviculture of gilthead sea bream (Sparus aurata). Sea bream larvae were randomly divided into 4 experimental groups in triplicates: group A larvae (control) fed rotifers followed by Artemia nauplii; group B fed a combined diet (50%) of rotifers–Artemia and preserved copepods; group C fed rotifers followed by preserved copepods; and group D fed preserved copepods solely. Survival and biometric data were analysed together with major molecular biomarkers involved in growth, lipid metabolism and appetite. Moreover, fatty acid content of prey and larvae was also analysed. At the end of 40 days treatment, a stress test, on the remaining larvae, was performed to evaluate the effects of different diets on stress response. Data obtained evidenced a positive effect of cofeeding preserved copepods during sea bream larviculture. Higher survival and growth were achieved in group B (fed combined diet) larvae respect to control. In addition, preserved copepods cofeeding was able to positively modulate genes involved in fish growth, lipid metabolism, stress response and appetite regulation.  相似文献   

7.
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.  相似文献   

8.
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   

9.
Experiments on the live food requirements of cultured turbot larvae are described. A mixture of six species of unicellular algae did not sustain early larvae, but the growth and survival of larvae fed with rotifers were considerably improved when the rotifers were feeding on Isochrysis galbana rather than on Dunaliella tertiolecta. Oyster (Crassostrea gigas) larvae offered alone or with rotifers, did not produce higher larval growth or survival than rotifers alone. Black tanks were found to be more suitable than white tanks for rearing larval turbot.  相似文献   

10.
Striped trumpeter have a complex and extended larval phase and are difficult to culture. Two experiments were conducted in replicated, 300-l hemispherical tanks to determine if larval survival, growth, bacterial or fatty acid profile were improved by feeding non-enriched rotifers or rotifers enriched with algae or commercially available products, as well as the effect of an antibiotic, oxytetracycline (OTC). Larvae were stocked at 25 l− 1 and 15 l− 1 and reared until Day 16 and Day 19 in Experiments 1 and 2, respectively. In Experiment 1, the feeding treatments were non-enriched rotifers, or rotifers enriched on algae, DHA Selco (a fish oil based emulsion) or RotiMac (dried Schizochytrium). There were no significant differences in mean survival (± SD) across treatments, which were generally low at 14.6 ± 5.2%. Larvae reared on rotifers fed DHA Selco and RotiMac, had significantly higher proportions of incorporated DHA but no significant increase in growth. In Experiment 2, larvae were fed rotifers enriched on DHA Selco or AlgaMac 2000 and reared with or without the daily addition of 25 mg l− 1 OTC. At Day 19, there was significantly higher survival for larvae reared on AlgaMac 2000 and OTC, (37.4 ± 5.6%), than DHA Selco and OTC, (16.0 ± 7.4%), AlgaMac 2000 without OTC (7.0 ± 8.0) and DHA Selco without OTC (3.3 ± 1.2). Larvae reared with OTC were larger (279 ± 58 μg and 7.4 ± 0.2 mm) than without OTC (177 ± 40 μg and 6.3 ± 0.2 mm). The addition of antibiotics did not significantly influence fatty acid profiles of larvae. There were no significant differences in the percentage of DHA, 27.6 ± 2.8%, EPA 4.6 ± 1.0% or ARA 4.9 ± 0.4%. Larvae reared with OTC had significantly less ‘grey gut’ (a measure of intestinal dysfunction). The results indicated that bacterial infection was a major source of mortality in striped trumpeter larvae and compromised larval growth. Assessment of the bacterial flora indicated that antibiotic use reduced the bacterial load, but did not eliminate potential pathogens. Our study suggests that microbial control has a greater influence than lipid nutrition on the survival and growth of larvae during the rotifer feeding stage.  相似文献   

11.
The effects of four light intensities on growth and survival of first‐feeding stage black sea bass larvae Centropristis striata were investigated in a controlled‐environment laboratory. Fertilized eggs, obtained from LHRHa‐induced spawning of captive broodstock, were stocked (72 eggs L?1) into twenty 15 L black tanks under light intensities of 100, 500, 1000 and 1500 lx, with five replicate tanks per treatment. The photoperiod was 12L:12D, the temperature was 20°C and the salinity was 35 g L?1. Larvae were fed rotifers Brachionus rotundiformis from day 2 post‐hatching (d 2ph) at 5–10 rotifers mL?1. Microalgae Nannochloropis oculata and Isochrysis sp. were added (1:1) daily to maintain a density of 300 000 cells mL?1. Hatching success and larval growth and survival from d 2ph through d 15ph were monitored. Hatching success was 28–38% under all light intensities, and notochord length at hatching ranged from 2.8 to 3.0 mm, with no significant differences among treatments. By d 15ph, growth (mg wet weight) was significantly higher in the 1000 lx (0.914) and 1500 lx treatments (0.892) than in 100 lx (0.483), and a highly significant trend (P<0.01) towards increased survival with increasing light intensities was observed, from 1.3% at 100 lx to 13.9% at 1500 lx. Higher light intensities within the range of 100–1500 lx improved growth and survival of early larval black sea bass, suggesting that even higher light intensities may improve culture performance. This is consistent with conditions in shallow, near‐shore locations where eggs and larvae are distributed in nature.  相似文献   

12.
A feeding study was conducted in the winter 2001 to determine the effects of feeding rotifers (Brachionus plicatilis) enriched with various levels of essential fatty acids on the growth and survival of haddock larvae (Melanogrammus aeglefinus). Rotifer enrichment treatments were: 1) mixed algae, 2) high DHA (docosahexaenoic acid, 22:6n-3), 3) high DHA and EPA (eicosapentaenoic acid, 20:5n-3), and 4) DHA, EPA, and AA (arachidonic acid, 20:4n-6). Larvae were fed rotifers enriched with the different treatments from days 1 to 16 post-hatch. From day 17 until 25 all treatment groups were fed rotifers reared on mixed algae and then weaned onto the International Council for Exploration of the SEA (ICES) Standard Reference Weaning diet (http://allserv.rug.ac.t/aquaculture/rend/rend.htm) over a five day period. The experiment was terminated on day 41 post-hatch. The enrichment treatments affected the fatty acid composition of the rotifers and correlated with the accumulation of these fatty acids in the haddock larvae. However, no significant differences in larval growth or survival to 40 days post hatch were detected, suggesting that all treatments provided the minimal essential fatty acid requirements for haddock.  相似文献   

13.
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.  相似文献   

14.
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.  相似文献   

15.
The effects of tank colour, larval stocking density, antibiotic administration and water exchange on survival and moulting of blue swimming crab, Portunus pelagicus, were determined. Circular 4‐m3 experimental larval‐rearing tanks were used in triplicate for all treatments. White, dark grey, blue and brown were tested as tank background colours. The stocking densities tested were 10, 20, 40, 60, 80 and 100 larvae L?1. The effect of oxytetracycline was estimated by comparing a treatment with oxytetracycline to a treatment without oxytetracycline administration. The daily water exchange rates tested were 0%, 25%, 50% and 100% of the tank volume. In all treatments, the larvae were fed with Artemia nauplii, rotifers and encapsulated Spirulina. The highest percentage survival was observed in the dark‐grey tanks when the stocking density of larvae was 20 larvae L?1. No larva reached the juvenile crab size in white tanks. No significant difference in survival was found between treated and non‐treated larvae with oxytetracycline when the daily water exchange rate was more than 50%.  相似文献   

16.
The point of no return (PNR) and disappearance of the oil droplet were measured in Chirostoma estor larvae as a function of the time of first feeding. In a separate trial, growth and survival of larvae fed rotifers enriched with Chlorella sp., cod liver oil and corn oil were assessed. Fatty acid and lipid composition of eggs, oil droplets, egg yolk, feed and larvae were also evaluated. The PNR was found between 7 and 8 days posthatching (dph). Total oil droplet depletion occurred between 7 and 11 dph, depending on the time of first feeding. Best growth and survival were obtained in larvae fed with Chlorella‐enriched rotifers, followed by those fed cod liver oil‐enriched rotifers. In larvae fed corn oil, Chlorella and cod liver oil‐enriched rotifers, total oil droplet depletion took place on days 9, 10 and 11, respectively. There was a direct relationship between presence and duration of oil droplets and the survival of larvae under different starvation conditions. The feed source could prolong the existence of the oil droplet depending on particular dietary supply of essential fatty acids; the time of its disappearance could be a useful indicator of larval vigour and health status.  相似文献   

17.
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.  相似文献   

18.
The current best practice intensive culture of larval Atlantic cod includes feeding rotifers from onset of exogenous feeding until 25–30 days after hatching. These larvae grow considerably slower and develop higher frequencies of deformities than larvae reared in semi‐extensive systems, using copepods as feed. The present study compares the micronutrient concentrations in rotifers with those of copepods, with the aim of identifying nutrients that may be limiting for normal growth and development of cod larvae. An additional criterion used is the nutrient requirements given for fish in general, by NRC (1993) , as nutrient requirements of cod remains to be determined. Rotifers were fed on four different diets, consisting of baker's yeast with cod liver oil (3.3 : 1 dry weight (DW)/v), baker's yeast with Algamac 2000TM (3.5 : 1 DW), baker's yeast with live algae Chlorella (4.1 : 1 DW), and Culture Selco 3000TM (CS). CS was a complete commercial diet for rotifers while the other diets are considered as based on raw ingredients. Compared with copepod nutrient levels, rotifers grown on yeast‐based diets supplemented with either cod liver oil, Algamac 2000 or Chlorella were apparently sufficient for covering the requirements in cod larvae for all the B‐vitamins, except thiamine. Rotifers cultured on the CS diet also had sufficient amounts of thiamine. Of the minerals, only calcium and magnesium were sufficient, using this criterion while iron was on the borderline. However, with reference to the requirements given for larger fish ( NRC 1993 ), only thiamine, vitamin A, manganese, selenium and perhaps copper, appear too low in the rotifers cultured without extra micronutrient supplementation. The other nutrients were present at levels intermediate between copepod and fish requirement levels. This study suggests that it is necessary to develop enrichment techniques to produce rotifers with sufficient amounts of all micronutrients. Such techniques will also be important tools for determining which nutrients are present at levels below the actual requirements in cod larvae.  相似文献   

19.
It currently remains unclear if rotifers contain sufficient mineral levels to meet larval fish requirements. In this study, rotifers were enriched with a commercial enrichment (control), or with additional iodine, iodine and copper, or iodine, copper and manganese, and the effects of feeding these rotifers to Atlantic cod (Gadus morhua) larvae from 3 to 18 days post hatch were investigated. Rotifer enrichment with minerals was successful, but Mn enrichment also increased rotifer zinc levels. No differences were observed between treatments in larval growth or survival, or in the mRNA levels in the majority of the redox system genes analysed. Only Zn levels increased in cod larvae in response to mineral enrichment of rotifers. Apart from Zn, little evidence was found to suggest that cod larvae require increased concentrations above the control rotifer levels of the essential elements studied here.  相似文献   

20.
This study aimed to establish feeding strategies covering the whole larval period of the forktail blenny, Meiacanthus atrodorsalis, based on the standard hatchery feeds of rotifers and Artemia. Three purposely designed experiments were conducted to determine the appropriate times and techniques to transition larvae from rotifers onto Artemia nauplii of a Great Salt Lake (GSL) strain, and a specialty AF strain, as well as subsequent transition onto enriched metanauplii of GSL Artemia. With a 3‐day co‐feeding period, larvae adapted well to a transition from rotifers to newly hatched GSL Artemia nauplii as early as 5 days posthatching (DPH), and as early as 3 DPH when fed the smaller AF Artemia nauplii. However, prolonging the rotifer‐feeding period up to 11 DPH did not negatively affect survival. Larvae fed Artemia nauplii of the AF strain showed 17–21% higher survival, 24–33% greater standard length and body depth, and 91–200% greater dry weight, after 20 days relative to those fed nauplii of the GSL strain. Meanwhile, enriched Artemia metanauplii of the GSL strain were shown to be an acceptable alternative to AF Artemia nauplii for later larvae, producing similar survival and growth when introduced from 8 DPH. Based on our findings, we recommend feeding M. atrodorsalis larvae rotifers as a first food between 0 and 2 DPH, introducing AF Artemia nauplii from 3 DPH, followed by enriched GSL Artemia metanauplii from 8 DPH onward, with a 3‐day co‐feeding period between each prey change.  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号