Microparticulate Diet Research Articles

Optimization of weaning strategy in the climbing perch (Anabas testudineus, Bloch 1792) larvae on growth, survival, digestive, metabolic and stress responses.

A 30-day experiment was carried out to know responses of different weaning approaches to the growth and survival of Anabas testudineus larvae. A total of 10800 larvae (Avg. weight 0.016 ± 0.03mg; 3DPH) were randomly distributed in nine treatments (triplicates), including two controls. The strategies are as follows: C1 (Control I): feeding with live food (LF) for 30days and C2 (Control II): feeding with microparticulate diet (MPD) for 30days; T1: LF for 5days and MPD for next 25days; T2: LF for 10days and MPD for next 20days; T3: LF for 15days and MPD for next 15day; T4: LF for 20days and MPD for next 10days; T5: LF for 25days and MPD for next 5days; T6: LF for 5days, then 25% LF replacement by MPD for next 5days, 50% LF replacement by MPD for next 5days, 75% LF replacement by MPD for next 5days, and 100% LF replacement by MPD for last 10days; and T7: LF for 10days, then 25% LF replacement by MPD for next 5days, 50% LF replacement by MPD for next 5days, 75% LF replacement by MPD for next 5days, and 100% LF replacement by MPD for last 5days. Significantly (p < 0.05) higher WG and SGR were recorded in T2 (213.17 ± 0.32, 23.98 ± 0.02) followed by T6, whereas the lowest was found in C2. Significantly higher (p < 0.05) percentage survival was manifested in the T7 (31.83 ± 0.22), followed by T2 (24.75 ± 0.13), and the lowest survival was observed in the C2. The digestive enzyme activities were found to be non-significant (p > 0.05) between different treatment groups. The alanine aminotransferase (ALT), aspartate aminotransferase (AST), lactate dehydrogenase (LDH), and malate dehydrogenase (MDH) were reported to be significantly higher (p < 0.05) in C2 (68.52 ± 0.08, 19.55 ± 0.10, 21.79 ± 0.04, and 0.044 ± 0.01) followed by T1; however, their reduced level was observed in C1. The activity of superoxide dismutase (SOD), catalase (CAT), glucose, and cortisol levels was observed significantly (p < 0.05) higher in C2 and lower in C1 and T2. As per the finding, it can be recommended that the appropriate weaning time for A. testudineus larvae is from 13 DPH onwards, in which larvae can be fed an initial ten days LF afterward MPD and the best weaning strategy can be adopted as in the T7 group for higher survival percentage.

Reproduction, Early Development, and Larval Rearing of the Climbing Perch Anabas testudineus (Teleostei: Anabantidae) in Captivity

Induced spawning, early development, and larval rearing of the climbing perch Anabas testudineus were examined under captive conditions. Five female climbing perch [125.33 ± 3.27 mm SL; 70.67 ± 5.59 g BW] were paired with apparently mature males (108.50 ± 3.97 mm SL; 39.27 ± 4.70 g BW) and induced to spawn with 5,000 IU human chorionic gonadotropin (hCG) + 0.5 mL Ovaprim kg BW-1. All hCG + Ovaprim-injected fish spawned 9 – 11 h after hormone administration but saline-injected fish (control group) failed to spawn. Mean egg production per female, fertilization and hatching rates, and larval production per female were 7,667 ± 1,313, 98.11 ± 1.63, 61.01 ± 19.92, and 4,435 ± 1,041 %, respectively. Fertilized eggs (1.52 – 1.96 mm in dia) were almost spherical, non-adhesive, transparent, and buoyant due to a large, single oil globule (515 ± 33 μm in dia). First cleavage appeared 30 min post-fertilization (MPF) and egg development lasted for 20 – 24 h post-fertilization (HPF) (29°C). Newly hatched climbing perch larvae [1.73 ± 0.08 mm in total length (TL)] with yolk volume (YV) and oil globule volume (OGV) of 0.545 ± 0.104 and 0.072 ± 0.013 mm3, respectively, had no pigmented eyes or functional mouth parts and digestive tract, and immobile with the yolk sac pointed upward. Eyes became pigmented and both mouth and anus opened in 1 d old larvae (2.09 ± 0.04 mm TL) in preparation for exogenous feeding. Except for body depth (BD) and pre-anal length (PAL), a general increase in TL (1.73 – 3.72 mm), eye diameter (ED) (0.164 – 0.378 mm), head length (HL) (0.205 – 0.923 mm), and mouth gape (MG) size (0.308 – 0.552 mm) was observed, coinciding with yolk resorption in 7 d post-hatched larvae. Climbing perch larvae were reared at 4 stocking densities (25, 50, 75, 100 larvae L-1) and fed solely on live food (Brachionus rotundiformis from 2 – 12 d and Artemia nauplii from 13 – 40 d) or co-fed live food and microparticulate diet (MPD) (Artemia nauplii from 2 – 15 d and Artemia + MPD from 16 – 40 d). Mean survival rates at lower densities (25 – 50 larvae L-1) were significantly higher than those reared at 75 and 100 larvae L-1 (P &lt; 0.05). Furthermore, climbing perch larvae co-fed Artemia nauplii and MPD showed better survival (28.67 – 81.00%) than those fed solely on live food (24.88 – 64.00%). However, at the end of the 40 d trial period, growth parameters did not vary significantly among densities (P &gt; 0.05), except for the condition factor in larvae co-fed Artemia nauplii and MPD. Taken together, results demonstrate the effectiveness of hCG + Ovaprim for captive breeding and observations on the early development of climbing perch, and the feasibility of rearing the larvae at 25 – 50 L-1 on a combination of Artemia nauplii and MPD under laboratory conditions.

Comparing the performance of four commercial microdiets in an early weaning protocol for European seabass larvae ( Dicentrarchus labrax )

The promise of an off-the-shelf, microparticulate diet for first feeding marine larval fish is still one of the ‘holy grails’ of the hatchery manager. Replacing the laborious live feed production facilities with high-quality microdiets will greatly increase marine larval production, improve hatchery consistency and will help in cost reduction in fry production. Over the last decades, many scientific and industrial efforts have focussed on developing microparticulate diets to reduce or replace the use of live feed for growing marine fish larvae in hatcheries. However, in most professional hatcheries, an extended live feed period is still the standard procedure. Thus, this study aimed to compare the performance of four state-of-the-art commercially available microdiets used in an early weaning protocol to the standard Artemia-based feeding. European seabass larvae were used as a model organism. The three most relevant parameters, survival, growth and deformities were used for the performance-rating of the four different microdiets. The results of the study depict that early weaning of European seabass between 15 and 20 days post-hatching (dph) onto the commercially available microdiets still result in lower survival, reduced growth and an increase in deformities in the early-weaned treatments. Nevertheless, one microdiet outperformed the others in this study, resulting in significantly fewer deformed larvae and improved growth. However, larvae fed with Artemia only still yielded the best results considering growth, survival and deformities.

Effects of weaning on survival and growth of silver therapon ( Leiopotherapon plumbeus ) larvae fed live and artificial diet

This study examined the effects of early weaning strategies on growth and survival of the silver therapon Leiopotherapon plumbeus larvae. In Trial 1, four larval age groups (8, 14, 20 and 26 days post-hatch (dph)) were abruptly weaned to commercial powdered tilapia diet and compared with wild copepod-fed group as the control. In Trial 2, another batch of three weaning age groups were subjected to gradual weaning (8 dph larvae with 8 days co-feeding, 14 dph larvae with 6 days co-feeding and 20 dph larvae with 4 days co-feeding) with Artemia nauplii prior to weaning on commercial powdered prawn diet and compared with a control group consisted of larvae fed exclusively on Artemia nauplii. Both weaning trials were conducted for 21 days. A gradual weaning strategy promoted better survival (22.2%–40.0%) among weaning age groups than the abrupt weaning strategy (2.2%–36.7%). Except for those weaned at 26 dph, abrupt weaning resulted in significantly poor growth and survival among all weaning age groups compared with the wild copepod-fed control group. The highest survival and growth were observed in 20 dph larvae with 4 days live food co-feeding, although the values were significantly lower than the Artemia-fed control group. These results suggest that abrupt weaning at 26 dph, and gradual weaning for 4 days from 20 dph promote successful rearing of silver therapon larvae and that a microparticulate diet specifically formulated for this species needs to be developed.

Captive broodstock development, breeding and seed production of Anthid fish (family: Serranidae) Marcia's anthias, Pseudanthias marcia in recirculation aquaculture system (RAS)

Marcia's anthias, Pseudanthias marcia Randall and Hoover, 1993, belonging to the subfamily Anthiinae (family: Serranidae) is a highly sought after marine ornamental fish mainly due to its vibrant pink shade. The present study reports the first successful captive brood stock development, spawning, and larval rearing of P. marcia. Brood stock was developed in a 5-ton recirculation aquaculture system (RAS) using 12 wild caught juveniles. After 6 months of rearing, the fish (8–9.5 cm size) started courtship behavior. Spawning occurred at 1900 to 2100 h. The eggs (mean size - 617.9 ± 14.9 μ) were transparent, pelagic, non-adhesive and with single oil globule. The eggs hatched out after an incubation period of about 14–16 h at a water temperature of 29 °C. Newly hatched larvae measured 1206.6 ± 100.02 μ in total average length and increased to 1852.9 ± 24.68 μ at 48 h post hatch (ph). Mouth opened at 48–50 h post hatch (ph) and measured 76 to 80 μ. Larval rearing trials were conducted using rotifer (L and S type), wild zooplankton, copepod nauplii, artemia nauplii and microparticulate diet. Primordial fin development started by the 10th day post-hatching (dph) (larval size ~2.9 mm) while the opercular and dorsal spines were fully formed by 15 dph (total length of the larva was 4.4 mm). Larvae metamorphosed to miniature adult shape by 32–34 dph and on 50 dph they reached the pink colored juvenile stage (42–43 mm) and at this stage, they were transferred to nursery rearing tank. Four treatments with different feed combination were tried and treatment III with wild copepod gave an average survival of 5.2 ± 1.07% and treatment IV with Parvocalanus crassirostris gave an average survival of 7.3 (±2.51) %.

Combined diet of yeast, fermented soybean meal, and microparticulate as larval feed in extensive rearing systems for seed production of the oriental river prawn Macrobrachium nipponense

The present study aims to evaluate the effects of several types of larval feed on seed production of the oriental river prawn Macrobrachium nipponense and water quality in extensive rearing systems. Healthy M. nipponense were distributed into fifteen 15-m2 pond outdoors, and each pond was stocked with 90 prawns including 41 egg-bearing (berried) female prawns, 37 not bearing female prawns, and 12 male prawns for larval production. The experimental design was completely randomized, with four diet groups (diet A: soybean homogenate, diet B: yeast, diet C: yeast + fermented soybean meal, and diet D: yeast + fermented soybean meal + microparticulate diet) and one no feeding control and three replications. There are equal levels of the total protein content in diets A–D. Higher larvae and postlarvae number was obtained for diet C and diet D. Furthermore, the increase of M. nipponense larvae and postlarvae in diets B–D can result in the decrease of zooplankton and increase of phytoplankton in the pond during some periods, simultaneously improving the water quality. The Spearman correlation coefficient (rM,N) between the amounts of larvae and postlarvae of M. nipponense per pond and zooplankton per pond during the entire experiment period was − 0.56. The highest juvenile M. nipponense production was obtained in the diet D group (3140.00 ± 461.63), which was slightly higher than that in the diet C group (2940.33 ± 382.60). The juvenile M. nipponense production in diet B (2303.00 ± 449.23) was also significantly higher compared to diet A (1106.33 ± 176.64) and the control group (1039.67 ± 212.85). There were no significant differences in the amounts of juvenile M. nipponense between the control and diet A groups, which indicated that the soybean homogenate could not increase the amount of M. nipponense juveniles. Our results clearly showed that diet D significantly raised per unit yield of prawn seed comparing with no feeding and other diet group in extensive rearing systems and that the cost of producing prawn seed with diet D is low, which provide an important foundation for the expansion of oriental river prawn culture.

Growth, Survival, and Whole‐body Proximate and Fatty Acid Composition of Haddock, Melanogrammus aeglefinus L., Postlarvae Fed a Practical Microparticulate Weaning Diet

AbstractFurther development of high‐quality feeds for hatchery‐reared haddock in the North Atlantic would benefit from a standard formulation that can be used as a reference for hatcheries and laboratory studies. A practical microparticulate diet (PMD) developed and evaluated with newly metamorphosed juvenile haddock, Melanogrammus aeglefinus L., postlarvae is proposed. Survival of fish fed PMD was just as high (88–89%; P &gt; 0.05) as those fed a high‐quality imported feed (Biokyowa). Alternatively, fish fed PMD had higher (P &lt; 0.05) final fork lengths (39.5 vs. 35.1 mm), wet weights (851.3 vs. 580.2 mg) and weight gains (1637.2 vs. 1115.7%). No differences (P &gt; 0.05) in whole‐body moisture (846–857 g/kg), ash (17–18 g/kg), or protein (101 g/kg) contents were found. Lipid content of fish fed PMD (26 g/kg) was higher (P &lt; 0.05) than those fed Biokyowa (21 g/kg) despite PMD containing 15 g/kg lower dietary lipid, suggesting higher intake and/or lipid retention. The PMD formulation proved to be a highly suitable weaning diet for haddock postlarvae based on high feed acceptance, survival, and fish growth. Given the economic and logistical difficulties associated with importing commercial weaning feeds, this easily produced practical weaning diet has good potential for use by laboratory researchers and farm managers for hatchery‐based nutrition research with haddock postlarvae.

Use of agar-bound microparticulate diet as alternative food for tropical abalone, Haliotis asinina (Linnaeus 1758) post-larvae in large-scale cultures

The efficacy of using agar-bound microparticulate diet (A-MPD) as alternative food for abalone Haliotis asinina Linne post-larvae in large-scale culture was investigated. Larvae sourced from the hatchery-bred (HB) and wild-sourced (WS) broodstock were fed with either diatoms (TMT1-NF), agar-bound microparticulate diet (TMT2-A-MPD), or a combination of both feeds (TMT3-NF + A-MPD) in six 2-m3 tanks replicated over time. Three hundred thousand veliger larvae were stocked/tank containing 80 corrugated plates with mucus trails hanging on bamboo poles. Feeds were given at 0900 h starting at day 3 with seawater flow through introduced every 1400 h starting day 5. Two-way analysis of variance determined significant differences (p < 0.05) in survival and shell length between larval sources and feed types. Tukey’s post hoc test established differences among treatment means. At day 30, survival for HB- and WS-sourced larvae was significantly higher (42%) in TMT3 compared with TMT2 having 35% for HB and 38% for WS (p < 0.05). Larvae fed with TMT1 had significantly lowest survival among the three treatments. Survival at 60 and 90 days did not show significant difference for TMT2 and TMT3 regardless of broodstock source. Post-larval shell growth (90 days), from both sources fed with TMT2 and TMT3, was significantly higher than TMT1 (p < 0.05). Larval performance did not show any significant interactions between HB and WS broodstock. The use of A-MPD alone or in combination may elicit improvement in survival and shell length growth in abalone larvae regardless of larval sources. A-MPD may be used as full or partial replacements to diatoms as alternative food for abalone post-larvae in large-scale culture.

Growth and muscle cellularity of diploid and triploid Atlantic cod (Gadus morhuaLinnaeus, 1758) larvae

Summary The aim of this study was to compare somatic growth and muscle fibre development in diploid and triploid siblings of Atlantic cod (Gadus morhua Linnaeus, 1758) during the larval stage. Newly hatched larvae were transferred into 200-L tanks, three tanks per ploidy group (70 larvae L−1, continuous light, gradually increasing seawater temperature 7–11°C and flow rates 50–117 L h−1). Larvae were fed rotifers from 2 to 22 days post hatch (dph), Artemia 19–31 dph and weaned onto a microparticulate diet from 26 dph until the end of the experiment. Measurements of growth (dry weight, standard length) and muscle cellullarity were taken at intervals between 1 and 44 dph. Ploidy groups showed a similar performance throughout the trial, although a marked stagnation in growth was observed for triploids during the weaning from Artemia onto dry feed. Overall, diploid and triploid cod larvae showed a similar development in muscle fibre growth pattern during the experimental period. For both groups, the total number of fast muscle fibres showed a 10-fold increase (from 384 to 3462), whereas the diameter of fast fibre increased from 8.9 to 13.3 μm (mean number from all treatments). Thus, a temporary but significant effect of triploidy on fast muscle fibre growth pattern was observed in 19 dph larvae in terms of fibre size and number, with triploids showing larger mean fast fibre diameter (11.62 ± 0.63 vs. 10.05 ± 0.34) and a lower number of fibres with a diameter <5 μm than their diploid siblings. Thus, this was found to be related to larvae size and to the differences in total fast fibre cross sectional areas rather than to ploidy status. Overall, our results suggest possible deficiencies in nutrients’ digestion and absorption of triploid cod larvae particularly during the transitional period from live food to inert diets.

Evaluation of Agar-Bound Microparticulate Diet as Alternative Food in Abalone Hatchery: Effects of Agar Concentrations and Feeding Frequencies

The performance of an agar-bound microparticulate diet (A-MPD) was evaluated on feeding postlarval abalone Haliotis asinina, focusing on the effects of agar concentrations and feeding frequencies. Larval abalone, obtained from the Southeast Asian Fisheries Development Center, Aquaculture Department hatchery, were reared in 60-L flow-through tanks with UV-filtered seawater. They were fed 1,200 mg A-MPD bound with either 5.0 mg/mL agar solution, 7.5 mg/mL agar solution, 10.0 mg/mL agar solution, and 12.5 mg/mL agar solution, or a natural diet consisting of diatoms at different feeding frequencies (daily, every other day, or every 2 d) starting at day 5. A 5 × 3 factorial experiment in a completely randomized design tested the effects of various treatments on postlarval settlement and survival after days 15 and 90. Scheffé's postcomparison test determined differences among treatments means. Postlarval settlement and survival were not significantly different in diets bound with higher agar concentrations and tested in 3 feeding frequencies. At lower levels of agar incorporation in diets, however, settlement and survival counts became significantly higher on daily feeding. Postlarval settlement and survival were significantly highest with abalone fed a diet bound with 7.5 mg/mL agar solution on a daily feeding frequency. Average percent weight loss in the feed was higher with lower levels of agar incorporation. Average particle size of both A-MPD and diatoms was 4–5 µm. Crude protein content of A-MPD was 42.7%; that of diatoms was 14.9%. A-MPD may be used as alternative food in abalone hatcheries with the incorporation of 7.5 mg/mL agar solution fed daily to abalone.

Early Weaning of Sea Bass (D. labrax) Larvae: Effects on Growth Performance and Digestive Enzyme Activities

In this study, effects of early weaning of sea bass (D. labrax) by microparticulate food on larval development and digestive enzyme activities, acid protease and alkaline protease were investigated until day 40. Larval rearing was conducted in closed sea water systems. Experiments were triplicated on 3 different weaning protocol that introduced on day 15 (MD15), day 20 (MD20) and day 25 (MD25) and also no microparticulate diet (MD) distributed in the control group. At the end of the experiment at 40-day, larval growth was calculated and the best values were obtained from MD25. Statistical differences among groups were not important (P>0.05) whereas MD15 was found different than the other groups (P 0.05) while control group was found statistically different (P<0.05). According to histological analysis, gastric glands and formation of functional stomach were observed on day 24-25 in all experimental groups. Acid protease activity firstly detected at 25 DAH. Control group was found different than the other groups (P<0.05). Finally, in terms of both growth parameters and survival rate and digestive enzyme activities it is clearly concluded that MD supplementation could be started after 25 DAH in D. labrax larviculture.

Determination of apparent protein digestibility of live Artemia and a microparticulate diet in 8-week-old Atlantic cod Gadus morhua larvae

A technique was developed to determine apparent digestibility coefficients (ADCs) of protein in microparticulate and live feeds for marine fish larvae. The technique is analogous to methods used for larger fish and allows for an in vivo measurement of protein digestibility by employing a spectrophotometric protein assay for protein determination and rare earth oxides as inert digestibility markers. Either a microbound microparticulate diet developed in our laboratory or Artemia nauplii were fed to 8-week-old Atlantic cod as a single 30-min feeding and fecal solids collected 6 h later. Protein ADCs for the two diets were significantly different (P=0.016) with determined ranges of 47 to 58% and 76 to 86%, (Artemia and microparticulate diets, respectively). Measured ADCs are presented as a range to account for the possibility of leaching of protein from the microparticulate diet, and the evacuation (loss) of marker from the live prey during the 30-min feeding. It is suggested that this new technique will assist researchers in selecting experimental larval feeds with the most nutritive potential for extended feeding studies. Detection limits for this technique were determined to be 8.6 μg for protein and 0.020 and 0.038 μg for yttrium (Y2O3) and dysprosium (Dy2O3) markers, respectively, in collected fecal solids.

Embriões liofilizados e flocos de &lt;em&gt;Artemia&lt;/em&gt; no cultivo pós-larval de &lt;em&gt;Litopenaeus vannamei&lt;/em&gt; (Boone, 1931)

The objective of the study was to evaluate the growth and survival of Litopenaeus vannamei post-larvae fed with freeze-dried embryos and Artemia flakes as feeding supplements to a microparticulate diet (DMP). In treatments T1, T2 and T3, the shrimp were fed with DMP and after 2 hours, received supplements of FLO (T1); EMB (T2); and the same DMP previously offered (T3). In T4, post-larvae were fed with DMP but without additional supplementation. There was no significant difference (p > 0.05) in shrimp survival after the experimental period of 21 days. On the other hand, the absolute weight gain (mg of dry weight) of post-larvae whose diet was supplemented with EMB (T2) was significantly higher (p Artemia embryos and recommend their inclusion in the post-larval diet of Litopenaeus vannamei

Effect of Microparticulate Diets on Growth and Survival of Spotted Sand Bass Larvae, Paralabrax maculatofasciatus, at Two Early Weaning Times

Abstract Early weaning in spotted sand bass larvae, Paralabrax maculatofasciatus, was evaluated, testing a combination of two weaning times, 17 and 22 d after hatching (d.a.h.), and three different microparticulate diets. Protein in diets was mainly from sardine meal and from 15% squid meal, beef blood meal, or fish protein hydrolysate. Anatomical (standard length), histological (gut development), and biochemical (highly unsaturated fatty acids) parameters were measured in larvae, as well as survival and resistance to a stress test measured 40 d.a.h. For larvae weaned at 17 d.a.h., the best growth and survival were obtained with diets containing fish protein hydrolysates; for larvae weaned at 22 d.a.h., best results were obtained with squid meal and fish protein hydrolysate. Growth and survival were significantly lower when using beef blood meal in both weaning treatments. The best relative and total survival were for larvae weaned at 22 d.a.h. After the resistance test, 100% survival occurred in larvae fed on any microparticulate diet and either weaning treatment. No significant differences in arachidonic acid, eicosapentaenoic acid, or docosahexaenoic acid concentrations in fish fed on any diet occurred. Results suggest that weaning at 22 d.a.h. with diets containing fish protein hydrolysate or squid meal is preferred by this species.

Effects of Early Weaning on Growth and Digestive Enzyme Activity in Larvae of Sea Bass (Dicentrarchus labrax L.)

The influence of early weaning on digestive enzymes, growth, and survival in sea bass larvae were investigated. Larvae were reared in a closed sea water system and first fed Artemia nau- plii eight days after hatching. Three weaning periods were compared by introducing a micropar- ticulate diet on day 15, 20, or 25. The control continued to be fed only Artemia. The lowest growth and survival rates were obtained in the 15-day group while the highest were in the 25- day group. After weaning, protease activities (trypsin, chymotrypsin, elastase, pepsin) dropped in all groups, indicating malnutrition. Amylase activity slightly increased in all experimental groups due to the higher starch content in the microparticulate diet than in Artemia and the absolute and relative lipid contents were lower in groups fed the microparticulate diet. Lipase activity suddenly dropped after weaning but slightly rose from day 35 until the end of the exper- iment (day 40). Due to decreased larvae development, survival, and digestive enzyme activity, weaning at 20 days after hatching, synchronous to formation of the stomach and enzymatic activity, is strongly recommended.

Successful culture of larvae of Litopenaeus vannamei fed a microbound formulated diet exclusively from either stage PZ2 or M1 to PL1

In three separate experiments, harpaticoid copepods Tisbe monozota (alive and dead) and a microparticulate microbound diet were evaluated as alternatives to live Artemia nauplii as food, beginning at either stage PZ2 or M1, in the larval culture of Litopenaeus vannamei. Larvae were cultured in 2 L round bottom flasks at a density of 150 L − 1 ( Experiment 1) and 100 L − 1 ( Experiments 2 and 3) at 28 °C, 35‰ salinity and 12:12 LD photoperiod, and fed 4×/day – 1 . Larvae were initially fed a mixture of phytoplankton to stages PZ2 or M1 and then fed either live Artemia, live or dead copepods, or a microparticulate microbound diet. The experiments were terminated and all larvae were harvested when more than 80% of larvae had molted to postlarvae 1 (PL1) within any flask representing any of the treatments. The comparative value of the different diets and feeding regimes was determined by mean survival, mean dry weight and total length of individual larva, and percentage of surviving larvae that were PL1. Trypsin activity of samples of larvae from each treatment was also determined. The microparticulate microbound diet effectively served as a complete substitute for Artemia nauplii when fed beginning at stage M1. When fed at the beginning of the PZ2 stage, survival was comparable to that of larvae fed Artemia, but mean dry weight, mean total length, and percent of surviving larvae that were PL1 generally were significantly less. Responses to the feeding of copepods, whether fed dead or live, as a substitute were generally significantly less than those of larvae fed either the Artemia nauplii or the microparticulate diet. Values of trypsin activity (10 − 5 IU/μg – 1 dry weight) corresponded to the relative proportions of the different larval stages within a treatment, with higher activity being characteristic of early stages. Previously demonstrated successful results with another species of crustacean suggest that the microparticulate microbound diet has characteristics that should be effective in the culture of the carnivorous stages of other crustacean and fish larvae that are currently fed live Artemia nauplii.

Lipid Nutrition and Feeding of Cobia Rachycentron canadum Larvae

AbstractThis study examined the fatty acid composition of cobia Rachycentron canadum eggs and yolksac larvae, as well as the ovaries of wild caught females as an initial guide to lipid nutritional requirements. A 2‐wk feeding study also was conducted to investigate the effectiveness of four dietary treatments on the growth and survival of cobia larvae. Cobia eggs in the tailbud stage contained 31.4 ± 1.3 μg lipid/egg. After hatching, the amount of lipid decreased significantly (P &lt; 0.05) from 28.3 ± 0.3 to 23.2 ± 0.1 μg lipid/larvae during the yolksac larval stage (days 1 to 3 after hatching). Ovaries from wild caught adults and captive spawned eggs and yolksac larvae contained high levels of PUFAs with docosahexaenoic acid (DHA), eicosapentaenoic acid (EPA), and arachidonic acid (ARA) accounting for approximately 80% of the total suggesting that cobia larvae may have a high dietary requirement for these fatty acids. For the feeding study, larvae were fed: 1) Artemia only; 2) enriched rotifers for 1 d only + microparticulate diet (day 313); 3) enriched rotifers for 3 d (day 3–5) + Artemia (day 3–13); and 4) enriched rotifers for 6 d (day 3–8) + Artemia (day 3–13). Cobia larvae began feeding on rotifers 3 d after hatching and on newly hatched Artemia nauplii by the fifth day following the onset of exogenous feeding (day 7). On day 7, no differences in larval growth were found among larvae fed rotifers for 3 versus 6 d, whereas larvae fed only Artemia or rotifers for I d followed by microparticulate diet were significantly smaller (P &lt; 0.05) and did not survive beyond day 9 and 13, respectively. The results of the feeding study indicate that cobia larvae require rotifers for a minimum of 4 d following the onset of exogenous feeding.

Reducing Artemia use in the culture of Atlantic cod ( Gadus morhua)

The acquisition and production of Artemia for the feeding of larval marine fish can constitute a significant portion of total fry culturing costs. The availability and price of Artemia can vary widely from year to year and, recently, Artemia cysts attained record high prices. This experiment was conducted to examine early weaning of cod ( Gadus morhua) larvae followed by supplementing microparticulate diet (MPD) with reduced Artemia rations. The objective was to determine whether Artemia use could be minimized while maintaining high growth and survival through supplementation of the MPD diet. Eggs were volumetrically counted to achieve a stocking density of 75 larvae l −1. The experiment consisted of a control group (100% A), which was fed live food during the experimental period, and three experimental treatments. All treatments were run in triplicate. The three experimental treatments received MPD and 50% of the amount Artemia in the 100% A treatment (50% A), MPD and 25% of the amount Artemia in the 100% A treatment (25% A), and MPD only (MPD). Standard lengths and dry weights were collected at hatch, 8, 22, 36, 50 and 64 days post-hatch (dph). Survival was calculated by counting all remaining fish at the conclusion of the experiment. The results indicate that the 100% A, 50% A and 25% A treatments did not differ significantly in standard length, dry weight, specific growth rate or survival. The MPD treatment had lower growth and survival than any of the treatments receiving Artemia. This study supports that, when Artemia prices are high (>US$50/kg), significant savings are possible for marine larval fish culture by using co-feeding strategies similar to those presented here.

Effect of an experimental microparticulate diet on the growth, survival and fatty acid profile of gilthead seabream (Sparus aurataL.) larvae

In recent years, a great deal of interest has emerged in the development of microdiets as an economic alternative to live food, in the larval culture of marine fish species. The ability to grow Sparus aurata larvae on a prototype microparticulate diet was examined. To achieve this objective, four feeding regimes differing in the time when the microdiet was introduced (3, 7 or 12 days) and one based exclusively on an inert diet were tested, during the first 22 days of larval life. Significant differences in larval growth were found between the experimental feeding regimes and their corresponding controls (enriched rotifers during the whole experimental period); the larvae in the co-feeding regimes and with an exclusive microparticulate diet were always significantly smaller than larvae fed on rotifers alone. However, the difference was minimised by introducing the inert diet at a later date. A lower survival was found in larvae with a co-feeding regime, in comparison with the control treatments and the survival was significantly lower in larvae fed exclusively on a microparticulate diet. The fatty acid analysis revealed that the experimental microencapsulated diet and the rotifers enriched with Protein Selco® presented relatively similar fatty acid content. In spite of the slightly higher (n−3)/(n−6) and Docosahexaenoic acid (DHA)/Eicosapentaenoic acid (EPA) ratios and somewhat lower highly unsaturated fatty acid (HUFA) content found in the inert diet, the fatty acid composition of the diets cannot explain the differences found in larval performance. The results revealed that the complete replacement of live prey with the tested microparticulate diet is still not possible in S. aurata larval rearing. Nevertheless, better growth and survival results and a substantial reduction in the daily supply of live food can be achieved with a combination of microdiet and live prey.

Effects of fish oil, DHA oil and lecithin in microparticulate diets on stress tolerance of larval gilthead seabream (Sparus aurata)

The effects of natural fish oil, DHA oil and soybean lecithin in microparticulate diets on stress tolerance of larval gilthead seabream (Sparus aurata) were investigated after 15 days feeding trials. The tolerance of larval gilthead seabream to various stress factors such as exposure to air (lack of dissolved oxygen), changes in water temperature (low) and salinity (high) were determined. This study showed that microparticulate diet with natural fish oil and soybean lecithin was the most effective for increasing the tolerance of larval gilthead seabream to various stresses, and that microparticulate diet with natural fish oil and palmitic acid (16∶0) was more effective than microparticulate diet with DHA oil and soybean lecithin.