Replacement of live food with a microbound diet in feeding Litopenaeus setiferus (Burkenroad) larvae

Microbound feeds have been well accepted by shrimps and farmers in many penaeid shrimp hatcheries. The present study focused on an adequate level of replacement of Artemia nauplii and microalgae by a microbound diet for rearing Litopenaeus setiferus (Burkenroad) larvae. A microbound diet (MBD) consisting of fishmeal, squid meal, shrimp meal, yeast meal and soybean meal was used. The first experiment was designed to obtain the optimum level of MBD to complete the live feeding schedule, from Protozoea (PZ_III) to Mysis (M_III). The experimental levels of the microbound diet tested were 2, 4, 6 and 8 mg MBD L^?1 day^?1. The next step was to determine the Artemia nauplii replacement level from PZ_I to M_III by MBD. These experiments were carried out either in the presence (Experiment 2) or in the absence of algae (Experiment 3). Four replacement levels were tested: 0% (4 mg MBD L^?1 day^?1: 1 Artemia nauplii mL^?1), 40% (5.5 mg MBD L^?1 day^?1: 0.6 Artemia nauplii), 60% (6.5 mg MBD L^?1 day^?1: 0.4 Artemia nauplii) and 100% (8 mg MBD L^?1 day^?1: 0 Artemia nauplii). In all experiments growth, survival, development, quality index (QI) and performance index (PI), were used to determine the optimum concentration of microbound diet. Results showed that 6 mg MBD L^?1 day^?1 can be recommended as a complement to live food for L. setiferus larvae from PZ_III to M_III. In the presence of algae, maximum growth and survival may be obtained in 40–60% (5.5–6.5 mg MBD L^?1 day^?1) of Artemia nauplii replacement levels. In the absence of algae, the Artemia nauplii replacement resulted in slower development, less salinity resistance, lower growth and lower survival than was obtained in larvae fed with algae.     

Use of Cyclop-eeze as a substitute for Artemia nauplii in larval rearing of giant freshwater prawn Macrobrachium rosenbergii (De Man 1879)

Four feeding experiments, replacing 25% (T₁), 50% (T₂), 75% (T₃) and 100% (T₄), by dry weight, of the live feed Artemia nauplii for Cyclop‐eeze, a new larval feed that was claimed to contain the highest known levels of astaxanthin and omega‐3 polyunsaturated fatty acids, were compared against a control that was fed with Artemia and egg custard alone, to the larvae of giant freshwater prawn Macrobrachium rosenbergii (De Man 1879). Analysis of different production characteristics of the larvae revealed that the highest survival up to postlarvae (PL) stage was obtained for T₂ in which 50% of the Artemia nauplii were replaced by Cyclop‐eeze [freeze‐dried (FD) deep frozen (DF)], and the highest astaxanthin content of the larval tissue obtained in T₄ in which the larvae were fed 100% Cyclop‐eeze, although the survival rate was the lowest in this treatment. The costs of different treatments were also compared. The Artemia consumption million⁻¹ larvae was the highest in control (11490 g), followed by T₁ (8240 g), T₂ (4990 g), T₃ (3730 g) and T₄, which completely replaced Artemia from stage 5 onwards (1830 g). The highest consumption of Cyclop‐eeze million⁻¹ larvae was in T₄ (1670 and 10 880 g), followed by T₃ (850 and 5560 g), T₂ (410 and 2690 g) and T₁ (230 and 1490 g) of FD and DF, respectively. The astaxanthin contents of the late‐stage larvae fed under the four treatments were 24.90, 27.40, 28.60 and 35.60 μg g⁻¹ tissue for T₁, T₂, T₃ and T₄, respectively, while that of the control was 23.70 μg g⁻¹. The lowest cost of live feeds million⁻¹ PL was obtained for T₂ (US$ 428.60), followed by T₁ (US$ 490.46), control (US$ 529.07) and T₃ (US$ 583.26), while it was the highest for T₄ (US$ 890.93). The results indicated that Cyclop‐eeze could economically replace Artemia nauplii at 50% level that could significantly improve the survival and carotenoid composition of the larvae of M. rosenbergii.     

Infection and mortality by the yeast Metschnikowia bicuspidata var. bicuspidata in chinook salmon fed live adult brine shrimp (Artemia franciscana)

First-feeding chinook salmon were fed either live adult Artemia franciscana or commercial feed over a 15-week period. Unexplained mortality began occurring in the Artemia-fed fish after 35 days on the diets, with cumulative mortality reaching 34.5% in the Artemia-fed fish compared with 4.3% in feed-fed fish. Necropsy examinations revealed systemic fungal yeast infections and the causative agent was cultured from kidneys. Fungal cells were observed in the transport water of Artemia shipments and within the Artemia. The Artemia were purchased from a retail supplier, and originated from salt ponds in San Francisco Bay (SFB), California. Artemia infection rates ranged from 0.5% to 37.5% (mean 16.5±3.59%) in shipments received over a 5-week period. The fungus was characterized by morphological and physiological properties and was identified as Metschnikowia sp., a pathogenic yeast of aquatic invertebrates. The yeast grew at 9–27 °C, and 0–180 ppt NaCl, and could tolerate salinity of at least 270 ppt. Sequence analysis of the divergent D1/D2 domain of ascomycetous yeast 26S ribosomal DNA identified the organism as Metschnikowia bicuspidata var. bicuspidata. The organism was found in water from the salt ponds and probably entered from the bay. Mortality due to the fungal infection stopped after changes were made in the handling of incoming Artemia shipments.     

Phenotypic estimates and heritability values of Artemia franciscana

Artemia, in all stages of its life cycle, is suitable food for most diversified groups of aquatic animals. Although its size at different stages restricts its use as a food for some groups of fish, this problem can be overcome using selective breeding techniques. The formulation of any selective breeding programme calls for a proper understanding of the genetic architecture of the economically important traits of the population under study. Thus, heritability for certain important life history and reproductive traits was estimated in Artemia franciscana from the Great Salt Lake, Utah. In the present study, the sexwise heritability values for growth and reproduction traits were estimated using parent–offspring regression. The phenotypic parameters for the same traits are also recorded. The naupliar length was 487.0±2.0 and 490.6±1.8 μm for males and females, respectively, whereas the heritability values for naupliar length were 0.5851±0.2153 and 0.3766±0.1899 respectively. The length at 3 and 6 days of age were 1.87±0.03 and 4.10±0.08 mm, respectively, for males whereas 1.87±0.03 and 4.30±0.08 mm, respectively, for females. The heritability values for length at 3 and 6 days of age for males were 0.3272±0.3651 and 0.4965±0.2466, respectively, whereas the respective values for the females were 0.1167±0.3841 and 0.0222±0.2971. The estimates of length at first brood, pre‐reproductive period and number of offspring in first brood were 10.09±0.23 mm, 16.00±0.23 days and 53.57±1.37 days, respectively, whereas the heritability values for respective traits were 0.0403±0.1078, 0.3234±0.2874 and 0.3404±0.2202.     

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

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

A comparison of retinol, retinal and retinyl ester concentrations in larvae of Atlantic halibut (Hippoglossus hippoglossus L.) fed Artemia or zooplankton

Atlantic halibut (Hippoglossus hippoglossus L.) larvae were fed enriched Artemia or zooplankton in duplicate tanks from 0 to 60 days after first‐feeding. Both diets and the larvae were analysed for vitamin A (VA) in order to confirm earlier findings, in which Artemia fed larvae had lower levels of VA compared with larvae fed zooplankton. Furthermore, we wanted to investigate the composition of the retinoids in the larvae. The results showed that Artemia and zooplankton contains low levels of VA, probably too low to sustain the assumed requirement. Nevertheless, larvae fed Artemia had the same level of retinal and retinol as larvae fed zooplankton. We found a significant lower level of retinyl esters in larvae fed Artemia. The total VA level was lower in larvae fed Artemia only at the end of the feeding trial after the onset of metamorphosis. Our conclusion is that feeding Artemia to Atlantic halibut larvae is not likely to cause VA deficiency.     

Possible applications of modern fish larviculture technology to ornamental fish production

There has been rapid development in the marine foodfishlarviculture technology in Europe since the early eighties,especially in the flat fish, turbot and halibut, and the bass andbream species. The most significant improvements in the eightieswere the introduction of light control, artificial reproductiontechniques, appropriate water treatment and the use of rotifersand Artemia nauplii of specific sizes and in the late eightiesand early nineties the quality enhancement of live food organismsusing specific enrichment techniques. Present research is focusedon the implementation of several microbial techniques to improvethe hygiene of live prey and fish.Many of the modern larviculture techniques being used in marine foodfish could be adapted for application in the ornamental fish industry. For examples, research in the Onamental Fish Section, Primary Production Department, Singapore has demonstrated that the use of freshwater rotifers and Artemia nauplii would enable artificial rearing of Discus in the absence of the parent fish and improve the larval performance of Gouramis and Tetra larvae. The use of such small live food organisms is likely to facilitate breeding of new fish species with small larvae. Research has also indicated that the use of diets containing vitamin C and certain immuno-stimulants improved the stress resistance of guppy. Such techniques would have important application in the fish transport, an important aspect in the ornamental fish industry     

Bioencapsulation of five forms of erythromycin by adult Artemia salina (L.)

Uptake of five chemical forms of erythromycin by adult Artemia salina (L.) (erythromycin phosphate – EP, erythromycin stearate – ES, erythromycin estolate – EE, erythromycin hydrate – EH and crystalline erythromycin – CE) was investigated in two trials. In each trial, final erythromycin concentration in Artemia tissue and survival after a 12‐h bioencapsulation period were determined. In the first trial, Artemia tissue concentration after a 12‐h bioencapsulation period was significantly (P < 0.05) affected by erythromycin form with ES (68.5 ± 3.3 μg mL^?1, mean ± SEM) ≈ EH (61.2 ± 3.4 μg mL^?1) > CE (37.1 ± 10.7 μg mL^?1) > EP (16.4 ± 7.7 μg mL^?1) > control. In trial 2, Artemia tissue concentration was also significantly (P < 0.05) affected by erythromycin form with EE (111.4 ± 9.6 μg mL^?1) > CE (89.1 ± 1.7 μg mL^?1) > ES (78.9 ± 1.6 μg mL^?1) > EP (33.4 ± 5.2 μg mL^?1) > control. Survival was significantly affected by erythromycin form in trial 1 with EP=control (100 ± 0.0%) > ES (74.4 ± 2.0%) > CE (32.2 ± 0.3%) > EH (8.8 ± 4.4%). In trial 2, survival was also significantly affected by erythromycin form with EP=control (100 ± 0.0%) > ES (67.1 ±3.7%) > CE (52.5 ± 7.7%) > EE (5.0 ± 2.5%). Based on both uptake and survival, EP and ES appear to be appropriate compounds for bioencapsulation of erythromycin using live adult Artemia.