The Effect of Live and Artificial Diets on Growth, Survival, and Trypsin Activity in Larvae of Penaeus indicus

In this study, partial and total replacement of live diets (microalgae and Artemia nauplii) with microencapsulated diets (MED) are demonstrated for larval culture of P. indicus . Slower growth and lower survival rate of larvae fed experimental MED were significantly improved by a supplement of 15 cells/μL frozen mixed algae (1:2, Tetrtaselmis and Skeletonema ) during protod stages (PZ1–PZ3). This low level of algal supplement to MED resulted in survival (85–92%) equal to that obtained from control live diets (91%) during protod stages. These significant improvements in larval growth and survival are likely to be due to higher larval digestive enzyme activities and hence more efficient digestion of the artificial diet by the larvae. Like other penaeids, P. indicus larvae show high total and tissue trypsin activities during PZ stages, with a peak at mysis stage 1 (M1), and a decrease during subsequent stages when fed on conventional live diets of algae followed by Artemia during mysis stages. Larvae fed 15 ceUs/μL mixed frozen algae in addition to MED demonstrated a significantly higher trypsin activity throughout herbivorous larval stages in comparison to larvae fed solely on MED. A freeze dried alga Rhinomonas reticulata incorporated into a MED at 23Vo (v/v) induced larval trypsin activity equal to that produced by live algae. Hence, the algal substances, which trigger digestive enzyme production, may be retained within the microcapsules. At mysis stages, however, addition of live prey (one Artemia/ mL) to cultures fed with MED significantly improved growth and survival although it depressed trypsin activity. For mysis stages it appears that the use of predigested ingredients is necessary to improve the digestibility of formulated diets.     

Feeding larvae of winter flounder Pseudopleuronectes americanus (Walbaum) with live prey or microencapsulated diet: linear growth and protein, RNA and DNA content

A commercial microencapsulated diet was used as a total or partial replacement of live prey for feeding larvae of winter flounder Pseudopleuronectes americanus (Walbaum), a potential alternative finfish species for coldwater marine aquaculture. Growth performance (morphometric measurements and biochemical composition) and nutritional condition (RNA/DNA ratios) of larvae fed live prey (Brachionus plicatilis Müller), a microencapsulated diet or a mixed diet of live prey and microcapsules were compared. Newly hatched larvae were unable to digest microencapsulated diet; live prey at initial feeding was required for their survival and growth. Larvae offered a mixed diet showed slower growth than larvae fed exclusively with live prey. However, at the onset of stomach differentiation, RNA/DNA ratios (indicators of protein synthesis potential) of the larvae fed both diets became similar. We suggest that, at that stage (size 5.5–6.3 mm), enzymatic activity had developed enough to allow digestion of inert food. As the RNA/DNA ratio is a good indicator of nutritional condition, it appears to be an interesting tool for the assessment of diet adequacy in marine larval feeding technology.     

Replacement of Artemia franciscana Nauplii by Microencapsulated Diets: Effect on Development,Digestive Enzymes,and Body Composition of White Shrimp,Litopenaeus vannamei,Larvae

The effects of two microencapsulated feeds were evaluated on development, growth, survival, proteolytic activity, and biochemical composition of white shrimp, Litopenaeus vannamei, larvae. The treatments were: (1) basal microcapsules (BM), (2) microcapsules containing krill hydrolysate (BMK), and (3) live food control (LFC: Artemia franciscana nauplii) with all treatments receiving algae (Chaetoceros ceratosporum and Tetraselmis chuii). No significant differences were found in development index and survival among larvae. Growth rate was significantly higher in larvae fed LFC (15 ± 0.06%/d) as compared with those offered the BM diet (7.5 ± 0.5%/d) with the BMK (11 ± 0.04%/d) treatment producing intermediate results. The activity of total proteases and chymotrypsin decreased significantly after Mysis I (M_I) in larvae fed LFC or BMK. Protein content of larvae increased significantly toward PL₁. The acylglycerides content in M_III fed on LFC (2.3 ± 0.2%/dw) was higher than that M_I fed BM (1 ± 0.01%/dw). No difference was observed in the cholesterol (CH) content of the larvae. The acylglycerides/protein and cholesterol/protein ratios showed a decreasing pattern between M_I and PL₁, indicating that these two ratios were related to ontogenetic shifts. These results demonstrate improvements in microparticulate diets when krill hydrolysates are included in the formulation.     

Evaluation of various diets for the optimum growth and survival of larvae of the penaeid prawn Penaeus japonicus Bate

Four types of food were tested to determine their effects on the growth and survival of larvae of the penaeid shrimp Penaeus japonicus Bate. The food types were live cells of Candida utilis (yeast), freeze-dried Candida utilis, microparticulate diet, and microencapsulated diet (commercial product). The diatom Chaetoceros gracilis was fed to larvae as a control. Two sets of experiments were carried out; the first was run in outdoor 1.5 ton tanks, and the second in indoor 1.2 ton tanks. In the outdoor experiment, the best survival and growth from nauplius to postlarva stage were obtained using microparticulate diet. During the first week of culture, freeze-dried Candida utilis resulted in the highest growth and survival among examined diets, but both factors dropped dramatically after the mysis stage. In the indoor experiment, the best growth and survival were obtained using live cells of Candida utilis from nauplius stage to end of mysis stage followed by brine shrimp. Tested diets were analysed for their contents of crude protein, total lipids, total carbohydrates, amino acid profiles and fatty acid contents.     

Dietary influence on growth and development of flat oyster,Ostrea angasi (Sowerby, 1871), larvae

The influence of algal diet on survival, growth and development of hatchery reared flat oyster, Ostrea angasi, larvae was investigated in a series of uni, binary and ternary algal diet trials. Early stage larvae (140–230 μm shell length) generally grew faster than late‐stage larvae (230–340 μm shell length) when fed unialgal diets. Of the 24 algal diets evaluated, larvae fed unialgal diets of Isochrysis sp. (T. Iso), Nannochloropsis oculata, Tetraselmis chuii or Pavlova lutheri; a binary diet of T. chuii+T. Iso; or ternary diets of T. chuii+T. Iso combined with P. lutheri or N. oculata had the greatest larval growth, survival, development and metamorphosis, in the respective trials. The correlation between growth rate and spat produced in late‐stage larvae was stronger when fed unialgal diets (r = 0.75) than when larvae were fed either binary or ternary diets (r = 0.44 and r = 0.45 respectively). Marked differences in proportion of spat produced (24 h post metamorphosis) were evident among diets producing similar growth rates. For hatchery production of O. angasi larvae, ternary diets of T. chuii+T. Iso combined with either P. lutheri or N. oculata were the best diets to maximize larval growth rate, development and survival 24 h post metamorphosis.     

Co-Feeding of Pacu,Piaractus mesopotamicus Holmberg (1887), Larvae with Artemia Nauplii and a Microencapsulated Diet

Abstract

Aiming at a precocious substitution of live prey by artificial diet, a 20-day experiment with pacu, Piaractus mesopotamicuslarvae using co-feeding and abrupt weaning strategies was set up. At the end of the experiment, larvae fed Artemia showed the best results (P < 0.05) in weight, total length and biomass, compared with other treatments. Larvae fed exclusively a microencapsulated diet never ingested the diet. Diet ingestion in co-fed and abrupt-weaned larvae was low, but did increase during the experiment; however, Artemia influenced diet ingestion on co-fed larvae. Careful considerations should be given to diet processing and formulation to ensure survival and growth of larvae fed exclusively on prepared diets.     

A balanced amino acid diet improves Diplodus sargus larval quality and reduces nitrogen excretion

Fish larvae present high amino acid requirements due to their high growth rate. Maximizing this growth rate depends on providing a balanced amino acid diet which can fulfil larval amino acid nutritional needs. In this study, two experimental microencapsulated casein diets were tested: one presenting a balanced amino acid profile and another presenting an unbalanced amino acid profile. A control diet, live feed based, was also tested. Trials were performed with larvae from 1 to 25 days after hatching (DAH). Microencapsulated diets were introduced at 8 DAH in co-feeding with live feed and at 15 DAH larvae were fed the microencapsulated diets alone. Results showed a higher survival for the control group (8.6 ± 1.3% versus 4.2 ± 0.6% and 3.2 ± 1.8%) although dry weight and growth were similar in all treatments. The proportion of deformed larvae as well as the ammonia excretion was lower in the group fed a balanced diet than in the unbalanced or control groups (38.3% deformed larvae in control, 30% in larvae fed unbalanced diet and 20% on balanced diet group). Furthermore, larvae fed the microencapsulated diets presented higher docosahexaenoic acid and arachidonic acid levels. This study demonstrates that dietary amino acid profile may play an important role in larval quality. It also shows that balanced microencapsulated diets may improve some of the performance criteria, such as skeletal deformities, compared to live feeds.     

Feeding and digestion in the caridean shrimp larva of Palaemon elegans Rathke and Macrobrachium rosenbergii (De Man) (Crustacea: Palaemonidae) on live and artificial diets

Larvae of two caridean shrimp species, Macrobrachium rosenbergii (De Man) and Palaemon elegans Rathke, were fed live and artificial diets. P. elegans larvae fed exclusively live Artemia salina (15 nauplii mL^?1) developed into first postlarval stage (PL1) within 12 days at a temperature of 25°C and salinity 32.5 g L^?1. Their survival and mean total length at this stage were 88.5% and 6.7 mm respectively. M. rosenbergii larvae fed on 15 Artemia mL^?1 started to metamorphose into PLl within 24 days at 29–30°C and 12 g L^?1. Attempts to completely replace live Artemia for rearing P. elegans during early stages failed, and only a partial replacement was achieved for the larvae of both species. P. elegans larvae survived (49%) solely on a microgranulated diet (Frippak PL diet) from stage zoea (Z) 4–5 to PL1. Similarly, a microencapsulated diet (Frippak CD3) also sustained M. rosenbergii larvae from Z5–6 to PL1 with a 28% survival. Development of the larvae of both species was retarded by 2–3 days and their survivals were lower than those fed on the live diet. The inability of the early larvae of these caridean species to survive on artificial diets is attributed to their undeveloped guts and limited enzymatic capabilities. Trypsin activity in the larvae was determined for all larval stages. It was found that the highest trypsin activity, at stage Z4–5 in P. elegans and at stage Z5–6 in M. rosenbergii, coincides with a rapid increase in the volume of the hepatopancreas and the formation of the filter apparatus. These morphological changes in the gut structure appear to enable the larvae to utilize artificial diets after stage Z5–6. Low larval trypsin activities may be compensated by the easily digestible content of their live prey during early larval stages (Z1–Z4/5) and by longer gastroevacuation time (GET) and almost fully developed guts during later stages.     

Improving the fitness of Holothuria arguinensis larvae through different microalgae diets

Development and design of adequate feeding protocols on sea cucumber larvae are necessary for improvements on larvae growth, survival and production of competent juveniles. This work assessed the Holothuria arguinensis larvae growth and survival, fed with three different single microalgae diets of Chaetoceros calcitrans, Isochrysis galbana and Tetraselmis chui, and two microalgae diets based on a combination of C. calcitrans and T. chuii (C:T; 1:1) and C. calcitrans, T. chuii and I. galbana (C:T:I; 1:1:1) during 2 months. Holothuria arguinensis larvae fed with T:C:I, showed higher survival and larger larval and stomach sizes than the ones fed with the other diets. Comparing the results obtained from the single diets, H. arguinensis larvae fed with I. galbana grew and survived better during the first 5 days. However, higher growth was obtained on the larvae fed with C. calcitrans from day 5 to day 12; since this day, larvae fed with T. chuii showed the largest size. These results could be related to the different microalgae size and morphology, in addition to the nutritional value of the different microalgae used. However, no competent larvae that metamorphosed into doliolaria were obtained during this experiment. The tanks used were transparent, which could be causing light stress to the larvae, since competent larvae were obtained in opaque production tanks in our aquaculture installations during the same time period. The combined diet of C. calcitrans, T. chuii and I. galbana (C:T:I) could improve the growth and larvae competency of H. arguinensis.     

Retention efficiency and release of nutrients in the digestive tract of larval shrimp (Penaeus japonicus Bate) using different microencapsulated diets

Retention efficiency and release of the nutrients in the digestive tract of larval shrimp (Penaeus japonicus) using the diets microencapsulated with gelatin and ethyl cellulose respectively were evaluated. The microencapsulated diets were produced using the fluidized bed coating process. 7.8 % gelatin and 4.2 % ethyl cellulose to the whole microencapsulated diet were respectively adopted as coating material. After immersion in 35 ‰ NaCl solution for 1 h, the nitrogen retention efficiency was significantly lower in the diet microencapsulated with gelatin compared with the diet microencapsulated with ethyl cellulose. Free amino acid retention efficiency of the diet microencapsulated with gelatin and ethyl cellulose was 12.9, 17.2 %, respectively. The mysis II larval shrimp (P. japonicus) 10 days after hatch were fed two different microencapsulated diets for 20 days and grew significantly more than the control larval shrimp fed with Artemia and shrimp flake. The nutrient components in intermediate intestine of larval shrimp were increased gradually in the order of the control (50 % shrimp flake + 50 % Artemia), Group I (50 % diet microencapsulated with gelatin + 25 % shrimp flake +25 % Artemia), Group II (100 % diet microencapsulated with gelatin), and Group III (100 % diet microencapsulated with ethyl cellulose). This study confirmed that the microencapsulated diets with slow and controlled release characteristic in the digestive tract of the larval shrimp (P. japonicus).     

Trypsin enzyme activity during larval development of Litopenaeus vannamei (Boone) fed on live feeds

Larval stages of the Pacific white shrimp, Litopenaeus vannamei (Boone) were fed standard live diets of mixed microalgae from the first to the third protozoea (PZ1 to PZ3), followed by Artemia nauplii until post‐larvae 1 (PL1). Trypsin enzyme activity for each larval stage was determined using N‐α‐p‐toluenesulphonyl‐l ‐arginine methyl ester (TAME) as a substrate. Results were expressed as enzyme content to assess ontogenetic changes during larval development. Tissue trypsin content (IU µg^?1 DW for each larval stage) was significantly highest at the PZ1 stage and declined through subsequent stages to PL1. This contrasts with previously observed patterns of trypsin development in Litopenaeus setiferus (Linnaeus) and other penaeid genera, which exhibit a peak in trypsin activity at the third protozoea/first mysis (PZ3/M1) larval stage. Litopenaeus vannamei larvae transferred to a diet of Artemia at the beginning of the second protozoea (PZ2) stage were significantly heavier on reaching the first mysis stage (M1) than those fed algae, while survival was not significantly different between treatments. At both PZ2 and PZ3 stages, trypsin content in larvae feeding on Artemia was significantly lower than in those feeding on algae. The rapid decline in trypsin content from PZ1 and the flexible enzyme response from PZ2 suggest that L. vannamei is physiologically adapted to transfer to a more carnivorous diet during the mid‐protozoeal stages.     

Influence of larval co-feeding with live and inert diets on weaning the tongue sole Cynoglossus semilaevis

The tongue sole Cynoglossus semilaevis, an inshore fish in China, has showed great potential in aquaculture recently. However, poor survival was recorded during the period of weaning from live Artemia to artificial diets. In this paper, the influence of co‐feeding larvae with live and inert diet on weaning performance was described. The C. semilaevis larvae were reared at 21 ± 1 °C and fed four different feeding regimes from 6 days post‐hatching (dph): A, Artemia (10 individuals mL^?1); B, Artemia (5 individuals mL^?1); C, mixed diet (10 Artemia individuals mL^?1 and 12 mg L^?1 inert diet); and D, mixed diet (5 Artemia individuals mL^?1 and 12 mg L^?1 inert diet). Rotifers were also supplied in all cases during the first days of feeding. Mixed diets of commercial formulated feed and live prey (rotifers and Artemia) allowed larvae to complete metamorphosis, achieving similar specific growth rate (SGR) (18.5 ± 1.4% and 18.7 ± 1.6%) and survival (40 ± 7.6% and 48.5 ± 6.8%) compared with larvae fed on live feed alone (SGR of 18.3 ± 1.2%, 19.3 ± 1.9% and survival of 41.2 ± 11.3%, 38 ± 4.9%). However, in metamorphosed fish, when live feed was withdrawn on 31 dph, there was significant difference (P < 0.05) in survival and growth among treatments. Metamorphosed fish, previously fed mixture diets during larval stages, had similar survival (62.1 ± 7.6% and 62.8 ± 3.9% for regimes C and D, respectively) but higher than that obtained for fish that previously fed on live feed (49.3 ± 2% and 42.1 ± 3.9% for regimes A and B, respectively) after weaning (day 60). The SGR of weaned fish previously fed live feed was similar (3.1 ± 0.6% and 2.92 ± 0.6% for regimes A and B, respectively) but lower than that recorded for fish that was fed from day 6 to day 30 on the mixed diet (4.5 ± 1.1% and 4.9 ± 0.3% for regimes C and D, respectively). It is suggested that weaning of C. semilaevis from early development would appear to be feasible and larval co‐feeding improves growth and survival.     

The effects of algal diets on population growth and egg hatching success of the tropical calanoid copepod, Acartia sinjiensis

As natural diets of fish larvae, a number of calanoid copepod species are being investigated for use as live prey in aquaculture hatcheries. One of these, the tropical calanoid copepod, Acartia sinjiensis, has good potential as a live feed for tropical reef fish larvae. However, the rearing techniques for A. sinjiensis require further development to improve productivity. This study was carried out to investigate the population growth and egg hatching success of A. sinjiensis when fed a range of mono-and binary algal diets, including algae in the form of frozen paste.For the population growth experiment, the final A. sinjiensis population, including eggs, nauplii, copepodites and adults, was determined after feeding eight algal diets (two frozen algae, four live monoalgal and two live binary algal diets) for 8 days at temperature 28 ± 1 °C; salinity 34 ± 1 psu and photoperiod 12 L:12 D. Five replicates, with an initial 12 adult A. sinjiensis per replicate, were set up for each treatment. In a separate experiment, effects of diets on egg hatching success were examined after 48 h incubation of eggs produced by A. sinjiensis fed the same eight diets.The results showed that diet significantly affected both population growth and hatching success of A. sinjiensis. Of the diets tested, the binary algal diets were more successful than monoalgal diets, while the frozen algae had little dietary value. The highest population growth was recorded on A. sinjiensis fed a binary diet of Tetraselmis chuii and the Tahitian strain of Isochrysis sp. (T-ISO) (final population: 1091 ± 80), which was significantly higher (P < 0.001) than all other diets tested except for the other binary diet of Nannochloropsis sp. and T-ISO (final population: 897 ± 123). Diet also had a significant effect (P < 0.001) on egg hatching rate, though the highest hatch rate was recorded with eggs produced by A. sinjiensis fed binary diet Nannochloropsis sp. and T-ISO (88.1 ± 2.1%), this was not significantly different from that of eggs produced by A. sinjiensis fed either T-ISO alone (88.0 ± 1.7%) or the binary algal diet of T. chuii and T-ISO (76.4 ± 7.1%). The results of this study suggest that among the diets tested, a combination of live T. chuii and T-ISO was the best for the culture of A. sinjiensis.     

Performance of Mixed Species and Mono‐specific Algal Diets for Culture of Larval Western School Prawns,Metapenaeus dalli

The effect of three mono‐specific and four combinations of the diatoms Chaetoceros muelleri, Chaetoceros calcitrans, and the chlorophyte Tetraselmis suecica on survival, development, and dry weight of the western school prawn, Metapenaeus dalli, was assessed from protozoea I until mysis I. The development and dry weight of larvae were significantly greater when fed diets comprising C. muelleri and/or T. suecica. A fourth diet, consisting of all three microalgal species also performed just as well. Survival alone was a poor measure of the performance of the various diets. Larvae fed with C. calcitrans, either alone or in a mixed diet with either C. muelleri or T. suecica, had significantly slower development and lower dry weight. Overall performance, assessed using the normalized biomass development index, determined that both mono‐specific and mixed diets containing C. muelleri and T. suecica were among the best for M. dalli larvae. These results for M. dalli are consistent with those found for commercially grown penaeid prawns. This study enhances the limited knowledge on the feeding requirements of metapenaeid prawn larvae. Moreover, the results will help improve hatchery methods for the aquaculture‐based enhancement of M. dalli in the Swan‐Canning Estuary and potentially increase the abundance of this iconic recreational species.     

Dual Benefits of Whey Protein Concentrate in a Microencapsulated Diet for Larval White Shrimp, Litopenaeus vannamei

Abstract— In this work a larval shrimp diet was spray-dried using a ratio of 75% whey protein concentrate and 25% mesquite gum as wall material, where the sole protein contribution to the diet was the whey protein concentrate. The microencapsulated diet exhibited the following physical properties: mean volumetric particle size of 49.3 om, characteristic floatability time 225.3 min, and density of 606 g/L. Its outer morphology was characterized by a dimpled spherical shape with no evident surface pores or cracks. Inner microstructure showed a central void, with the feed components finely embedded in the wall matrix. Two bioassays were performed with zoea of white shrimp Litopenaeus vannamei . In the first study, microencapsulated diet, and microencapsulated diet plus a single dose of live algae, were compared with a live algae control diet; in the second study, three co-feeding regimes consisting of microencapsulated diet + 10,30 and 60C. muellericellaL, respectively, were compared with the live algae control diet. In overall terms, the co-feeding regime with 30 cells/ OL produced larvae with carapace length (0.74-mm CL) and development index (4.5 DI) significantly superior to that of the live algae treatment (0.70-mm CL, 4.1 DI; respectively), and yielded similar individual dry weight (34-Og DW) and survival rate (58%). These results indicate that microencapsulated diets supplemented with live algae can produce responses similar to those of live feed. These results     

Variations on development and stress defences in Solea senegalensis larvae fed on live and microencapsulated diets

Growth, development, antioxidant enzymes, stress proteins (HSP70 and HSP60), lipid peroxidation (LP) and histology in Solea senegalensis larvae were followed from 8 to 30 days post hatching (dph). Larvae were fed on three different diets: (1) live Artemia nauplii, (2) microcapsules elaborated by internal gelation, (MA) and (3) these same microcapsules but 10-fold supplemented with vitamin A (MAV). The Artemia fed group showed higher growth and a faster metamorphosis than the ones fed with microencapsulated diets, although all had similarly high survival rates of 80%. Vitamin A (VA) supplementation improved growth and development from 15 dph in relation to the strictly inert diet (MA). Larvae fed with Artemia showed organs and tissues with a normal pattern of development, whereas histological alterations were seen in larvae fed with both inert diets. The antioxidant enzymes: catalase (KAT), superoxide dismutase (SOD), and total glutathione peroxidase (t-GPX) as well as LP levels and stress proteins (HSP70 but not HSP60), measured in whole larvae, showed diet and age dependence in their response. Larvae fed with both inert diets showed similar biomarker activities, but these activities were different (p < 0.05) from larvae fed with Artemia. That is, KAT and HSP70 were lower in larvae fed with live prey and t-GPX and LP levels were lower in larvae fed with the inert food. Among the factors responsible for increased antioxidant defenses were the initiation of metamorphosis and the use of inert food. This study suggests the usefulness of the biomarkers selected as tools to evaluate the effects of compound diets on larvae.     

The nutritional effect of Isochrysis galbana and Chaetoceros muelleri cultured with different seaweed extracts on the larval development,growth and survival of the marine shrimp,Penaeus indicus

The microalgae Isochrysis galbana and Chaetoceros muelleri were cultured with seaweed extract (SWE) from six different seaweeds and each SWE was used either as a supplement or as an alternative media to conventional f/2 medium. Microalgae cultured with only the f/2 media acted as the control treatment. I. galbana and C. muelleri were then fed to Penaeus indicus larvae, either singly or in combination, for 8 days to evaluate its nutritional quality. Shrimp larvae fed on microalgae cultured in f/2 media supplemented with SWE from Ulva lactuca or Enteromorpha intestinalis moulted faster (P < 0.05) to the second mysis stage compared with the control. Survival, total length and growth rates were better in shrimp larvae fed on microalgae previously cultured in media supplemented with SWE. In general, shrimp larvae fed microalgae cultured entirely in SWE performed equally well compared with the control. Shrimp larvae fed on mixed microalgae (I. galbana + C. muelleri) showed significantly better growth, survival and development compared with larvae on either single microalgal diet. It was concluded that microalgae cultured with SWE could be used as a low‐cost alternative media in producing live food for the hatchery production of shrimp larvae.     

Development of a Squid-hydrolysate-based Larval Diet and its Feeding Performance on Summer Flounder, Paralichthys dentatus, Larvae

Locally generated squid‐processing byproduct was processed into concentrated hydrolysate (22% solids, 17.3% protein, and 3.0% lipid, primarily phospholipids—11.6% eicosapentaenoic acid/24.5% docosahexaenoic acid on a lipid weight basis). Two microparticulate diets (65% protein, 19% lipid, 7.5% carbohydrate, and 19.12 MJ/kg energy, on a dry weight basis) were prepared using squid hydrolysate (SH) and squid‐herring hydrolysate as sole protein sources (73.3 and 78.65% of the whole diet, respectively). A 22‐d feeding trial with summer flounder, Paralichthys dentatus, larvae of 17 d after hatch showed that the survival rate (92%) of larvae fed SH was significantly (P < 0.05) higher than those of larvae fed live Artemia nauplii (81%) and a commercial diet, Proton (65%), while specific growth rates (SGR) were comparable (2.23% /d for SH and 2.86% /d for Artemia) with the lowest for Proton (1.39% /d). After switching from commercial and Artemia diets to a SH diet for 17 d following the 22‐d feeding, significant improvements were seen in survival rates of postweaning larvae fed previously commercial (65.28–76.57%) and Artemia diets (81.25–89.07%).     

Gelatin-walled microencapsulated diet for larval shrimp (Penaeus japonicus Bate) manufactured using the fluidized bed coating process

The gelatin-walled microencapsulated feed for larval shrimp (Penaeus japonicus) was produced using the fluidized bed coating process. The microencapsulated diet showed no significant agglomeration in the coating process and the diameters of the microdiet were in a normal distribution. Scanning electron microscopy microphotographs showed the appearance of a microencapsulated diet with a uniform surface and a continuous film around the core. The retention efficiency of vitamin C was 88.2% in the coating process. The inclusion efficiency, lipid encapsulation efficiency and nitrogen retention efficiency of the microdiet were 92.2 ± 1.6%, 76.8 ± 4.1% and 60.6 ± 5.2% respectively. The mysis α of P. japonicus were reared for 20 days to the later larval stage. The wet weight of larval shrimp increased 300.0% in the microdiet from 10 up to 30 day after hatching. The wet weight and the total length of larvae were greater in co-feeding compared with the control (P<0.05), but there was no significant difference in larval survival between co-feeding and control (P>0.05). There were significant differences (P<0.05) in the wet weight, total length and survival in the microdiet compared with the control. The results indicated a huge potential for the use of the gelatin-walled microencapsulated diet for the partial and total replacement of live food for larval shrimp.     

Effects of enriched Artemia by fish and soybean oils supplemented with vitamin E on growth performance,lipid peroxidation,lipase activity and fatty acid composition of Persian sturgeon (Acipenser persicus) larvae

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