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.     

The Influence of Artemia and Algal Supplements during the Nursery Phase of Rearing Pacific White Shrimp, Litopenaeus vannamei

A 21‐d nursery trial was conducted to evaluate various food supplements on growth and survival of postlarval (PL) Litopenaeus vannamei. Each of four treatments was provided with an equal quantity of a dried commercial feed throughout the study. Three treatments received algae paste (Thalassiosira weissflogii) supplemented every 3 d. These include F, commercial feed plus algae; FAr3, commercial feed plus algae plus Artemia every other day during the first 7 d; and FAr7, commercial feed plus algae plus Artemia every day during the first 7 d. The fourth treatment served as control (FNA); it relied only on the commercial feed plus naturally occurring algae. At the conclusion of the nursery period, there were no significant differences in survival or feed conversion ration for PL nursed in the various treatments. Artemia did have some effect in that PL receiving Artemia supplement for 3 d (FAr3) were significantly larger than those that did not. Algal paste in itself had no significant effect. Overall, results suggest an advantage to supplementing dried feed with Artemia for at least 3 d during the first week of nursery culture but little advantage to the use of a diatom paste as a food supplement.     

Effects of dietary phospholipids levels on growth performance,lipid metabolism,and antioxidant capacity of the early juvenile green mud crab,Scylla paramamosain (Estampador)

Four iso‐nitrogenous and iso‐lipidic diets were designed to investigate the effects of dietary phospholipids (PL) levels (with 0%, 1%, 2%, and 4% PL supplementation) on growth performance, lipid metabolism, and antioxidant capacity in early juvenile green mud crab (Scylla paramamosain). There were three replicates of 28 crabs (initial body weight from 42.02 to 42.44 mg) for each diet treatment, and growth trial lasted for 8 weeks. At the end of the growth trial, there was no significant difference in survival among all treatments. Crabs fed diet with 2% PL obtained highest weight gain (WG) and specific growth rate than other crabs. The molting frequency was not affected by different dietary PL addition. Besides, the contents of whole body lipid and long chain highly unsaturated fatty acids significantly increased with elevating dietary PL levels. In the hepatopancreas, crabs fed diet with 0% PL had significantly higher malondialdehyde concentration than other crabs. And crabs fed diet with 2% PL obtained significantly higher superoxide dismutase activity than crabs fed diets with 0% and 4% PL. Moreover, the mRNA expression of Na⁺/K⁺‐ATPase was significantly down‐regulated with dietary PL supplementation over 2%. Based on the second order polynomial regression analysis of WG, 2.37% dietary PL level was the optimal demand for early juvenile S. paramamosain. Moreover, we found crabs fed diet with 2% PL obtained better antioxidant capacity than other crabs.     

紫外辐射对条斑紫菜不同部位藻体光化学效率和光合色素含量的影响

实验室条件下研究了紫外辐射(UVR)对条斑紫菜藻体不同部位最大光化学效率(Fv/Fm)和光合色素含量的影响,以探讨条斑紫菜不同部位对紫外辐射反应的差异性。在全光谱 PAB(PAR+UV-A+UV-B,280~700 nm)和滤除紫外辐射UVR(UV-A+UV-B)的有效光辐射(PAR,395~700 nm)两种处理下进行测定。实验结果表明,PAB处理后的各部位藻体最大光化学效率下降程度均高于PAR处理后,且弱光期恢复程度低、速度慢。藻体不同部位间最大光化学效率下降程度也存在差异,藻体梢部对PAB的耐受性高,恢复也较快;基部耐受性最差,恢复也较慢。藻红蛋白(phycoerythrin,PE)和藻蓝蛋白(phycocyanin,PC)对不同辐射处理较敏感,PAB辐射处理后,各藻体部位的PE、PC含量均显著上升(P<0.05),其中藻体梢部PAB处理后的PE、PC含量的均极显著升高(P<0.01)。然而不同部位藻体在PAB和PAR照射下,叶绿素a(Chl.a)和类胡萝卜素(Car)并无显著变化(P>0.05)。藻体的紫外吸收物质(MAAs)的含量从基部到梢部逐步升高,不同辐射处理前后,各藻体部位的紫外吸收物质也未显著增加(P>0.05)。总之,条斑紫菜不同部位藻体光合生理特性存在较大差异。推测条斑紫菜应对紫外辐射的策略有遮蔽作用,积累紫外吸收物质和动态光抑制作用。     

Successful rearing of whiteleg shrimp Litopenaeus vannamei larvae fed a desiccation‐tolerant nematode to replace Artemia

The nematode Panagrolaimus sp. was tested as live feed to replace Artemia nauplii during first larval stages of whiteleg shrimp Litopenaeus vannamei. In Trial 1, shrimp larvae were fed one of four diets from Zoea 2 to Postlarva 1 (PL1): (A) Artemia nauplii, control treatment; (NC) nematodes enriched in docosahexaenoic acid (DHA) provided by the dinoflagellate Crypthecodinium cohnii; (N) non‐enriched nematodes; and (Algae) a mixture of microalgae supplemented in C. cohnii cells. In Trial 2, shrimp were fed (A), (NC) and a different treatment (NS) with nematodes enriched in polyunsaturated fatty acids (PUFAs) provided by the commercial product S.presso^®, until Postlarva 6 (PL6). Mysis 1 larvae fed nematodes of the three dietary treatments were 300 μm longer (3.2 ± 0.3 mm) than control larvae. At PL1, control shrimp were 300 μm longer (4.5 ± 0.3 mm) than those fed DHA‐enriched or PUFAs‐enriched nematodes. No differences were observed in length and survival at PL6 between control larvae and those fed DHA‐enriched nematodes (5.1 ± 0.5 mm; 33.1%–44.4%). Shrimp fed microalgae showed a delay in development at PL1. This work is the first demonstration of Panagrolaimus sp. suitability as a complete substitute for Artemia in rearing shrimp from Zoea 2 to PL6.     

Interaction of Phytochemical‐Quercetin with the Other Antioxidant,Ascorbic Acid and their Protective Effect in Tilapia after Ultraviolet Irradiation

Semi‐purified, casein‐gelatin‐based diets were prepared and supplemented with quercetin (Q) and/ or ascorbic acid (AA): control diet C–Q–(100 mg/kg AA), diet C –Q+ (100 mg/kg AA + quercetin 10 g/kg), diet C +Q– (1000 mg/kg AA), and diet C +Q+ (1000 mg/kg AA + quercetin 10 g/kg). These diets were fed to tilapia for 19 wk and then fish were divided into controls and ultraviolet (UV) treatments. Fish were exposed to UV radiation. Control groups were protected with a MYLAR^® polyester film and plexiglass. At week 20, the same fish were re‐exposed to UV radiation. Control groups of fish were protected by a double layer of MYLAR^® and the UV groups were exposed with no protection. Before UV exposure, 24 h after, and 7 d after the second treatment, fish liver and skin were dissected for Q and AA analyses. The proportion of oxidized ascorbate was significantly increased in fish from treatments C –Q– and C –Q+ . Q concentrations in fish after exposures were negligible in skin, whereas liver concentrations were significantly different among control (34 ± 10 μg/g) and UV‐irradiated fish (11 ± 6 μg/g), respectively. The interaction between these two dietary antioxidants may change after chronic UV irradiation.     

Growth and Survival of Juvenile Feather Duster Worms,Sabellastarte spectabilis,Fed Live and Preserved Algae

The use of live algae and preserved algal products was examined as to their utility in supporting growth and survival of the feather duster worm, Sabellastarte spectabilis. Hatchery‐reared 4‐mo‐old worms were provided the same cell densities of live T‐Iso, preserved T‐Iso, live Nannochlropsis sp., and preserved Nannochloropsis sp. over the course of 132 d. A group of worms placed in a water table that received a continuous flow of raw seawater served as controls. Live and preserved T‐Iso resulted in the highest survival (86.7 ± 6.2% and 78.3 ± 16.5%, respectively) compared to all the other treatments. Live T‐Iso fed worms resulted in significantly larger worms than all other treatments with the preserved T‐Iso treatment supporting similar growth to those being fed live Nannochloropsis sp. and exposed to raw seawater. The preserved Nannochloropsis sp. resulted in significantly lower survival and growth when compared to all the other treatments. Fatty acid profiles of the algal diets and worm carcasses obtained during the current investigation suggest that T‐Iso outperformed Nannochloropsis because of its higher energy or fatty acid content.     

Effects of total replacement of fish oil by pork lard or rapeseed oil and recovery by a fish oil finishing diet on growth,health and fish quality of gibel carp (Carassius auratus gibelio)

An 84‐day growth trial was designed to investigate effects of dietary replacements fish oil with pork lard (PL) or rapeseed oil (RO) on growth and quality of gibel carp (Carassius auratus gibelio var. CAS III) (initial body weight: 158.2 ± 0.2 g), and responses of the fish refed fish oil (FO) diet. Three isonitrogenous (crude protein: 30%) and isolipid (crude lipid: 10%) diets were formulated containing 7.73% FO, PL or RO. Five experimental treatments including FO group (FO), PL group (PL), RO group (RO), group fed PL for 42 days and refed FO for 42 days (PL+rFO), RO and refed FO group (RO+rFO) was tested. At the end of first 42 days, the fish fed PL and RO had higher mortality than that of the control (P > 0.05). At the end of whole experiment, fish fed PL and RO showed higher plasma cortisol than FO fish (P < 0.05). RO+rFO fish showed higher lysozyme activity than RO fish (P < 0.05). Fish growth and feed utilization, composition of whole body and muscle, free amino acids, texture, off‐flavour substances or sensory attributes were not affected by dietary treatments (P > 0.05). PL and RO diet decreased muscle EPA, DHA and n‐3/n‐6 ratio (P < 0.05), while FO‐refeeding had recovery effect. It can be concluded that the replacement of FO by PL and RO does not affect the growth, feed utilization or fish tasting quality in gibel carp. Fish muscle fatty acids modified by dietary PL and RO can be recovered by refeeding with FO diet.     

The effect of PUFA enriched Artemia on growth, survival and lipid composition of western rock lobster, Panulirus cygnus, phyllosoma

Western rock lobster, Panulirus cygnus, phyllosoma were grown from hatching to stage IV. Larvae were fed with Artemia enriched with a (i) base enrichment (Base) containing 520 g kg^?1 squid oil or tailor made enrichments in which oils high in polyunsaturated fatty acid (PUFA) have been added at the expense of squid oil. These treatments were (ii) base enrichment supplemented with docosahexaenoic acid (DHA) rich oil, (iii) base enrichment supplemented with arachidonic acid (AA) rich oil, or (iv) base enrichment supplemented with DHA and AA (D + A) rich oils. Total survival of phyllosoma to stage IV was high, with no significant difference between treatments (range 12.3–17.5%). By stage IV, the larvae fed the DHA or AA enriched Artemia were significantly larger (3.33 mm length) than larvae fed the Base or D + A enriched Artemia (3.18–3.24 mm length). Phyllosoma were sampled at stages II and III for biochemical analysis. The major lipid class (LC) in all phyllosoma was polar lipid (PL) (88.9–92.4%), followed by sterol (ST) (6.2–9.7%). Triacylglycerol (TAG), free fatty acid (FFA) and hydrocarbon/wax ester were minor components (≤1%) in all phyllosoma samples. In contrast, the major LC in all enrichments and enriched Artemia was TAG (76.3–85.1% and 53.4–60.2%, respectively), followed by PL (11.4–14.8% and 30.6–38.1% respectively). The main fatty acids (FA) in phyllosoma were 16:0, 18:1n‐9, 18:1n‐7, 18:0, AA, eicosapentaenoic acid (EPA) and DHA. Addition of AA, and to a lesser extent DHA, to enrichments resulted in increased levels of those FA in Artemia and phyllosoma compared with the Base enrichment. This was particularly evident for stage III larvae. Comparatively, elevated growth for phyllosoma to stage IV was achieved with DHA and AA enriched diets. Our findings highlight the importance of lipids and in particular essential long‐chain PUFA, as nutritional components for phyllosoma diets.     

Reproductive performance,survival and development of nauplii and copepodites,sex ratio and adult life expectancy of the harpacticoid copepod,Euterpina acutifrons,fed different microalgal diets

A series of laboratory experiments were conducted on the harpacticoid copepod, Euterpina acutifrons, to assess the influence of 10 different microalgal diets (four monoalgal and six mixed algal diets) on several parameters related to its productivity in culture. The four monoalgal diets were the Tahitian strain of Isochrysis sp. (T‐Iso), Pavlova salina (Pav), Tetraselmis chuii (Tet) and the diatom Chaetoceros muelleri (Chaet), the five binary diets were T‐Iso+Tet, Pav+Tet, T‐Iso+Pav, Tet+Chaet and Pav+Chaet, while the tri‐algal diet was T‐Iso+Tet+Pav. All diets were fed to copepods at 1500 μ gC L^?1 and in the case of binary or trialgal diets, carbon concentration was divided equally between the two or three algae offered. Among monoalgal diets, the diatom Chaet was excellent for E. acutifrons. Out of the 10 diets tested, the binary diet Tet+Chaet, which contained the diatom Chaet, was the best for naupliar production of single pair E. acutifrons (19.5±1.7 nauplii female^?1 day^?1), significantly (P<0.05) higher than all other treatments except for the Chaet treatment (P>0.05). Similarly, in the group naupliar production trial (50 adult E. acutifrons per replicate), Tet+Chaet produced a significantly higher number of nauplii (405.8±18.6 nauplii day^?1) than the other treatments (P<0.05). Tet+Chaet further supported the highest naupliar survival (82.0±2.8%) and copepodite survival (89.0±2.8%), while the mono‐algal diet Chaet produced the second highest naupliar (76.7±2.6%) and copepodite survival (83.5±2.6%). In contrast, Pav produced the lowest overall survival at the naupliar stage (30.0±2.9%), significantly lower than all other treatments (P<0.05). While development from newly hatched nauplii to copepodites was not significantly affected by diets, mean development time from nauplius to adult was significantly different among treatments. Mean development time from hatching (naupliar I stage; NI) to the adult stage was the fastest with Tet+Chaet and Chaet (6.8±0.0 days for both treatments), which was significantly faster than that of Pav, T‐Iso Pav+Tet and T‐Iso+Pav+Te treatment (P<0.05). E. acutifrons sex ratio was significantly affected by diets, and always skewed in favour of males. Feeding on Pav resulted in the lowest proportion of females (23.7±1.2%), significantly lower than for six of the other treatments (P<0.05). Adult females had longer average life expectancy than males for all treatments, and were the longest when fed Tet+Chaet (9.5±0.4 days), which was more than twice as long as the shortest lifespan recorded for the Pav treatment (4.2±0.6 days) (P<0.05). In summary, among 10 diets tested, the binary diet Tet+Chaet appeared to support the highest culture productivity of E. acutifrons while the diatom Chaet also performed well as a monoalgal diet.     

Effect of different dietary microalgae combinations on growth and survival of black‐lip pearl oyster (Pinctada margaritifera) larvae and the feasibility of replacing microalgae with a dietary lipid emulsion

A 10‐day experiment was performed to examine different mono, binary and ternary dietary combinations on survival and growth of D‐shaped and umbone black‐lip pearl oyster, Pinctada margaritifera, larvae. The three tropical microalgae species were the flagellate Isochrysis galbana clone T. Iso (CS‐177) and diatoms Chaetoceros calcitrans (CS‐178) and Chaetoceros muelleri (CS‐176) which were fed to D‐shaped and umbone larvae at a density of 7000 and 14 000 cells mL^?1, respectively. A second experiment was performed to investigate the feasibility of replacing T. Iso with a lipid emulsion for both D‐shaped and umbone larvae for 10 and 12 days, respectively. The treatments included only T. Iso, unfed and lipid emulsion to substitute T. Iso at levels of 10% (LIP10), 30% (LIP30) and 100% (LIP100). In the first experiment, results showed that a monospecific diet of T. Iso led to significantly higher (P < 0.05) survival and growth of D‐shaped larvae than all the other treatments. Meanwhile, D‐shaped larval survival was significantly lower when only fed C. calcitrans as well as growth for those fed C. calcitrans or in combination with C. muelleri. However, for umbone larvae, survival and growth were significantly higher when fed a binary combination of T. Iso and C. muelleri or the ternary combination of T. Iso, C. muelleri and C. calcitrans compared with all other treatments. For the second experiment, results showed that with increasing lipid emulsion replacement, survival of both D‐shaped and umbone larvae significantly decreased (P < 0.05); however, the LIP100 treatment was not significantly different (P > 0.05) from the unfed treatment. For D‐shaped larvae, no significant growth difference was detected (P > 0.05) between the T. Iso and LIP10 fed treatments while for umbone larvae, the T. Iso, LIP10 and LIP30 were not significantly different (P > 005). These results indicate that microalgae combinations appear more necessary for later staged P. margaritifera larvae. In addition, the use of a lipid emulsion appeared to provide some nutrition to the larvae, although more research should be conducted to improve the use of such replacements.     

Interactive effects of dietary vitamin C and phospholipid in micro‐bound diet for growth,survival, and stress resistance of larval red sea bream,Pagrus major

This study was conducted to examine the effects of dietary ascorbic acid (AsA) and phospholipid (PL) and their interaction on growth, survival, and stress resistance in red sea bream larvae. Twenty‐six days old red sea bream were fed nine micro‐bound diets supplemented three levels of AsA (0, 800 and 1600 mg kg^?1 diet) and PL (0, 20 and 40 g kg^?1 diet) for 15 days. Dietary AsA and PL were both significant factors on survival rates. There was also an interaction between dietary AsA and PL on survival rate (P < 0.05). The larvae fed 800 or 1600 mg kg^?1 AsA with 40 g kg^?1 PL diets showed the highest survival rate, with values similar to those of the live‐food supplemented group. Stress resistance against low salinity exposure significantly increased with increased dietary level of AsA and PL. However, significant interaction of AsA and PL was not detected. The larvae fed 1600 mg kg^?1 AsA with 40 g kg^?1 PL diet showed the highest stress resistance among all diets, but it was not significantly different than that of larvae fed 800 mg kg^?1 AsA with 40 g kg^?1 PL diet. This study clearly demonstrated that combined use of AsA and PL can improve survival of 26–40 days posthatching red sea bream larvae. Moreover, the present study suggested that 800 mg kg^?1 AsA with 40 g kg^?1 PL in diet was needed for producing high quality seedling under the stressful conditions.     

Development of diets for the intensive culture of Pacific lamprey

The Pacific lamprey Entosphenus tridentatus is an ancestral species of critical importance to the ecosystem and indigenous cultures in the Pacific Northwest. Conservation aquaculture has been proposed as a potential technique to restore Pacific lamprey populations. Intensive culture methods and diets for this species have not been developed. A sixteen week feeding trial tested the effects of seven diet treatments on the survival, growth, fatty acid profile and whole body lipid content of Pacific lamprey ammocoetes. Dietary treatments were: active dry yeast, yeast plus fish oil emulsion, micro‐algae, micro‐algae plus fish oil emulsion, yeast with micro‐algae, yeast with micro‐algae plus fish oil emulsion and yeast with larval fish diet. Each diet was offered to five replicate tanks stocked with 20 ammocoetes that were 51 days post hatch. Survival during the trial was not affected by diet. The greatest length and weight increases were in fish fed diets containing yeast. Growth decreased as the amount of algae in the diet was increased. Lipid retention was significantly higher in fish fed yeast with larval fish diet relative to the other treatments. Feed conversion ratio was lowest in fish fed diets containing yeast. Whole body fatty acid profiles tended to reflect the fatty acid profile of the diet. Percentages of 20:5n‐3 and 22:6n‐3 were significantly higher in fish fed diets containing fish oil emulsion. Overall, yeast with larval fish diet provided the best growth performance in larval Pacific lamprey.     

Tank culture of larval sunshine bass, Morone chrysops (Rafinesque)×M. saxatilis (Walbaum), at three feeding levels

Sunshine bass, a hybrid of female white bass Morone chrysops (Rafinesque) and male striped bass M. saxatilis (Walbaum), fingerling production occurs almost exclusively in ponds. To increase production and maintain year‐round production in temperate climates, indoor tank culture is required. While tank production of fingerlings has been demonstrated, little is known about feeding requirements. Sunshine bass larvae, stocked at 75 L^?1 in 100 L of brackish water, were fed sequentially with rotifers Brachionus plicatilis cultured with a Nannochloropis algae paste and enriched with highly unsaturated fatty acids, decapsulated Artemia nauplii, and a microencapsulated commercial diet. The larvae in one treatment (three replicates) were initially fed rotifers at a daily rate of 20 mL^?1, then nauplii at an initial rate of 2 mL^?1, and then the commercial diet at 1 g. Larvae in two other treatments received two and three times as much food daily. The highest feeding rate resulted in a survival (52.9%) that was significantly higher than the survival rate (22.4%) of larvae fed the least. The total biomass produced was the highest in the treatment receiving the most food. The lowest feeding rate produced the least fish, but they were the heaviest. The intermediate feeding rate produced the shortest fish (11.3 mm).     

Growth and immune response of giant freshwater prawn Macrobrachium rosenbergii (De Man) postlarvae fed diets containing Chlorella vulgaris (Beijerinck)

A 50‐day growth trial was conducted to evaluate the efficacy of Chlorella vulgaris (Beijerinck) as an ingredient in the diets of giant freshwater prawn Macrobrachium rosenbergii (De Man) postlarvae (PL30). Immune response (total haemocyte count and prophenoloxidase activity) was also assessed by subjecting postlarvae to a challenge test against Aeromonas hydrophila (Chester) for 14 days. Iso‐nitrogenous and iso‐lipidic test diets were prepared using a fishmeal‐based‐positive control diet (D0) and four basal diets with inclusion levels of 2% (D2), 4% (D4), 6% (D6) and 8% (D8) C. vulgaris. Postlarvae of M. rosenbergii were randomly stocked (mean initial body weight of 0.19 ± 0.02 g) in 30‐L tanks in three replicates per dietary treatment for evaluation of growth performance. Another set of postlarvae (mean initial body weight of 1.25 ± 0.02 g) was randomly distributed in 95‐L tanks in three replicates per dietary treatment for the assessment of immune response. Results showed that specific growth rate was significantly higher (P < 0.05) in postlarvae fed D4 and D6. Variations in values for carcass protein, lipid, moisture and ash were also evident. Postlarvae fed diets with Chlorella showed increased prophenol oxidase activity and total haemocyte counts. Moreover, survival rate after challenge with A. hydrophila was significantly increased (P < 0.05). Inclusion of C. vulgaris in diets enhanced immune response and resistance of M. rosenbergii postlarvae against A. hydrophila infection.     

Evaluation of partial substitution of live algae with dried Tetraselmis for larval rearing of black-lip pearl oyster, Pinctada margaritifera (L.)

Experiments were conducted with larvae of theblack-lip pearl oyster, Pinctadamargaritifera fed on a regime of living algae(an equal mixture of Tahitian Isochrysisaff. galbana and Pavlova salina)either partially or completely substituted withheterotrophically grown spray-dried algae (Tetraselmis suecica). Two experiments wereconducted; in the first, 1-day old larvae werecultured for 13 days and, in the second, 13days old larvae were culture for 7 days. Inboth experiments larvae were fed the followingproportions of live algae (LA) and dried Tetraselmis (DT); (1) 100% LA, (2) 75% LA +25% DT, (3) 50% LA + 50% DT, (4) 25% LA +75% DT; and (5) 100% DT. The optimal dietsfor maximum larval growth were 100% LA and75% LA + 25% DT resulting in larvae with amean shell length (SL) of 132 ± 3.8 and 131± 2.7 µm, respectively, at day 13. Thisshowed that 25% substitution of livemicro-algae with DT is possible withoutaffecting growth of P. margaritiferalarvae of less than 150 µm SL. There was nosignificant difference in survival of P.margaritifera larvae fed 100% LA, 75% LA +25% DT and 50% LA + 50% DT over a period of13 days. Highest survival (43.7%) occurred inlarvae fed 100% DT while lowest (approximately18%) occurred in controls (50% livemicro-algae and unfed) during the firstexperiment. The result of the second experimentindicated that with increasing size, larvae arecapable of accepting a higher proportion ofdried Tetraselmis in their diet. Therewere no significant differences in larvalgrowth or survival, between treatments where LAwas partially and completely substituted dietswith DT.     

Effect of dietary protein and lipid levels and protein–energy ratio on growth indices, feed utilization and body composition of freshwater prawn, Macrobrachium rosenbergii (de Man 1879) post larvae

A grow‐out experiment was designed to determine the effect of different dietary protein, lipid levels and protein–energy (P:E) ratio on growth performance and feed utilization of the freshwater prawn, Macrobrachium rosenbergii post larvae (PL) culture in pond net enclosures (hapa, 3.75 m^?3 each) for 12 weeks (84 days). The experimental treatments were assigned in triplicate. Six test diets were formulated to contain three different protein levels (300, 350 and 400 g kg^?1 diet) and two lipid levels (100 and 140 g kg^?1 diet) in a factorial manner (3 × 2) to provided six different dietary P:E ratio: 16, 17, 18, 19, 20 and 21 mg CP kJ^?1 g^?1). The result showed that the highest significant (P≤0.05) survival rate, growth indices and feed utilization were observed for M. rosenbergii PL fed a diet with a P:E ratio of 17 mg CP kJ^?1 g¹, whereas, the lowest value was recorded for prawns fed a diet with a P:E ratio of 20 mg CP kJ^?1 g^?1. Whole body contents of protein and lipid were highest (P≤0.05) when fed diets with 21 and 17 mg CP kJ^?1 g^?1 respectively. Concerning dietary protein levels, the highest (P≤0.05) values for survival and growth indices were observed for PL fed a diet containing 300 g kg^?1 diet protein. The same trend was observed for PL fed a diet with 100 g kg^?1 diet lipid level, irrespective of dietary protein levels. A diet containing 300 g kg^?1 protein and 100 g kg^?1 lipid with a dietary P:E ratio of 17 mg CP kJ g^?1 is recommended to stimulate growth performance and nutrients utilization efficiency of M. rosenbergii PL.     

紫外辐射对浒苔游孢子附着、萌发和幼苗生长的影响

为了探讨绿潮藻浒苔游孢子对紫外线(UVR)的敏感性,研究了相对于有效光辐射(PAR,P)增加UVA辐射(PAR+UVA,PA)和全波长辐射(PAR+UVA+UVB,PAB)对浒苔游孢子的光合效率、附着、萌发和幼苗生长的影响。实验结果表明,(1)强光[900μmol/(m2·s)]下PA和PAB辐射对浒苔游孢子的最大光化学效率(Fv/Fm)具有明显抑制作用,且辐射时间越长抑制作用越大。强光下PA和PAB辐射15、30、60min导致浒苔游孢子最大光化学效率分别下降为28.4%、42.4%、36.5%、52.1%、64.4%、54.5%;(2)游孢子在15min辐射期间的附着率分别为50.0%(P)、44.9%(PA)和23.9%(PAB),紫外辐射尤其是UVB显著抑制(延迟)了游孢子的附着(P<0.05),但对24h后游孢子的总附着率没有显著影响。不同辐射处理和处理时间之间存在显著交互作用(P<0.05);(3)阳光下PA和PAB对孢子萌发具有显著抑制作用,第3天PA和PAB处理的游孢子萌发率分别为P处理的57.0%和39.1%,游孢子的萌发存活决定于最初的3d,3d后的紫外辐射对幼苗的存活没有显著影响(P>0...     

Evaluation of two probiotics used during farm production of white shrimp Litopenaeus vannamei (Crustacea: Decapoda)

This study examined the effects of Bacillus licheniformis strain CIGBC‐232, isolated from the gut of shrimp Litopenaeus vannamei and having antagonistic activity against Vibrio harveyi, on the immunity and larval quality of L. vannamei at various ontogenetic stages, in two separate experiments: (1) PL2 to PL17 exposed to the strain CIGBC‐232 under laboratory conditions (2) zoea I to PL8 exposed to the strain CIGBC‐232 and EPICIN 3W probiotics under farming conditions. The first experiment showed that phenoloxidase, peroxidase and superoxide dismutase activities were improved in animals grown with CIGBC‐232 compared to the untreated control. In tests, the resistance to osmotic stress was also enhanced. During the second experiment, animals treated with CIGBC‐232 exhibited significant (P < 0.05) increases in phenoloxidase activity (30–40% higher in zoea I–II, mysis II–III and PL 2–7) and in the respiratory burst (30% higher from PL 2 to 7) as compared to those animals that received EPICIN 3W. There was no significant difference in the lectins and agglutinins (except in PL1, 6 and 7), in peroxidase and superoxide dismutase activities, in the resistance to osmotic stress, nor in the survival rate among treatments. CIGBC‐232 treatment was able to reduce, the level of presumptive Vibrio spp. with respect to EPICIN 3W treatment in the tank water as well as in animals. At the end of both experiments, the growth of shrimp, i.e. weight and length was increased by CIGBC‐232 treatment. This study showed the probiotic effect of CIGBC‐232, which appeared to have a better probiotic performance than EPICIN 3W treatment.     

Vaccination strategies with oral booster for surubim hybrid (Pseudoplatystoma corruscans × P. reticulatum) against haemorrhagic septicaemia

This study evaluated the efficiency of differently prepared vaccines against Aeromonas hydrophila in the hybrid surubim (Pseudoplatystoma corruscans × P. reticulatum). Survival and haemato‐immunological parameters were compared between the treatments: non‐vaccinated fish (C); bacterin‐vaccinated fish (B); bacterin plus oral booster vaccinated fish (B+O); bacterin and toxoid‐vaccinated fish (B+T) and bacterin, toxoid and oral booster‐vaccinated fish (B+T+O). Fourteen‐days vaccinated fish from B+O and B+T+O were fed with an oral booster for 4 days. After 1 week, the fish were intraperitoneally challenged with 2 × 10⁸ CFU mL^?1 of A. hydrophila. Fish from the treatment B+T+O showed the lowest cumulative mortality (11.36%) 96 h after challenge, compared with other treatments (22.72–44.04%), and a relative survival of 74%. Serum immunoglobulin in B+T+O fish was higher than in other treatments. All vaccinated fish showed an increased agglutination titre when compared with non‐vaccinated fish, both before and after challenge. Fish fed with oral booster showed an increase in phagocytic percentage before and after challenge. It can be inferred that the oral booster vaccination was efficient in reducing mortality in hybrid surubim by enhancing the response against haemorrhagic septicaemia due to A. hydrophila infection.