Depletion of florfenicol amine in tilapia (Oreochromis sp.) maintained in a recirculating aquaculture system following Aquaflor®‐medicated feed therapy

Aquaflor^® [50% w w^?1 florfenicol (FFC)], is approved for use in freshwater‐reared warmwater finfish which include tilapia Oreochromis spp. in the United States to control mortality from Streptococcus iniae. The depletion of florfenicol amine (FFA), the marker residue of FFC, was evaluated after feeding FFC‐medicated feed to deliver a nominal 20 mg FFC kg^?1 BW d^?1 dose (1.33× the label use of 15 mg FFC kg^?1 BW d^?1) to Nile tilapia O. niloticus and hybrid tilapia O. niloticus × O. aureus held in a recirculating aquaculture system (RAS) at production‐scale holding densities. Florfenicol amine concentrations were determined in fillets taken from 10 fish before dosing and from 20 fish at nine time points after dosing (from 1 to 240 h post‐dosing). Water samples were assayed for FFC before, during and after the dosing period. Parameters monitored included daily feed consumption and biofilter function (levels of ammonia, nitrite and nitrate). Mean fillet FFA concentration decreased from 13.77 μg g^?1 at 1‐h post dosing to 0.39 μg g^?1 at 240‐h post dosing. Water FFC concentration decreased from a maximum of 1400 ng mL^?1 at 1 day post‐dosing to 847 ng mL^?1 at 240 h post‐dosing. There were no adverse effects noted on fish, feed consumption or biofilter function associated with FFC‐medicated feed administration to tilapia.     

Antibacterial efficacy and pharmacokinetic evaluation of sanguinarine in common carp (Cyprinus carpio) following a single intraperitoneal administration

Sanguinarine (SA), with antimicrobial and antiparasitic activities against fish pathogens, exhibits great potential commercial use in aquaculture. However, little information on pharmacokinetics of SA restricts further application in aquaculture. In this study, pharmacokinetics of SA in common carp (Cyprinus carpio) following a single intraperitoneal administration [10 mg kg^?1 BW (body weight)] was evaluated by high‐performance liquid chromatography (HPLC). The peak concentration (C_max) of SA in kidney was 11.8 μg g^?1, which was higher than in other tissues and plasma. The terminal half‐life in fish tissue and plasma was as follows: 42.3 h (kidney) > 37.2 h (liver) > 20.1 h (gill) > 18.8 h (muscle) > 10.9 h (spleen) > 10.0 h (plasma). Additionally, we determined the bacterial loads in tissues of common carp infected with Aeromonas hydrophila after i.p. administration of SA at 0, 5, 10 and 20 mg kg^?1 BW. The results showed that i.p. administration of SA at 10 mg kg^?1 BW significantly enhanced antibacterial efficacy against A. hydrophila, where the antibacterial ratio in the gill, kidney, spleen and liver on day 5 was 95.13%, 93.33%, 90.09% and 92.82%, respectively. Overall, these results suggested the potential of SA to treat A. hydrophila infection in common carp farming industry.     

Effects of dietary mannan oligosaccharides in early weaning diets on growth,survival, fatty acid composition and gut morphology of gilthead sea bream (Sparus aurata,L.) larvae

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

Pharmacokinetics of florfenicol and behaviour of its metabolite florfenicol amine in orange‐spotted grouper (Epinephelus coioides) after oral administration

Pharmacokinetics and elimination of florfenicol and florfenicol amine in grouper held in sea water at 23.3 ± 0.8 °C were studied using HPLC method after they were given a single peroral dose of florfenicol at 24 mg kg^?1 body weight. Florfenicol was rapidly absorbed from intestine and distributed extensively to all the tissues examined. The maximum concentrations (C_max, μg g^?1 or μg mL^?1) in plasma and tissues were observed at 2–6 h (the time to reach maximum concentration, T_max) except for bile (T_max = 24 h) and were in the order of intestine (52.02 ± 25.07) > bile (49.41 ± 28.16) > gill (45.12 ± 11.10) > plasma (28.28 ± 5.43) > liver (21.97 ± 12.08) > muscle (21.63 ± 6.12) > kidney (20.88 ± 11.28) > skin (19.10 ± 5.88). The drug distribution level was higher in plasma than in extravascular tissues except for bile, based on the ratios of the area under concentration–time curve between tissue and plasma (AUC_{tissue/plasma}). The elimination of florfenicol was rapid in fish, and the corresponding half‐lives (T_1/2β) in the order of magnitude were bile (13.92 h) > muscle or liver (12.31 h) > skin (11.77 h) > plasma (11.57) > gill (11.04 h) > intestine (10.55 h) > kidney (10.05 h). The delayed T_max, lower C_max and longer T_1/2β for florfenicol amine compared with florfenicol were measured in grouper.     

Effects of partial substitution of dietary fish meal by fermented soybean meal on growth performance,amino acid and biochemical parameters of juvenile black sea bream Acanthopagrus schlegeli

A feeding trial was conducted to evaluate the effect of replacing fish meal protein with fermented soybean meal (FSM) on the growth performance, feed utilization, amino acid profile, body composition, morphological parameters, activity of antioxidant and digestive enzymes of black sea bream (Acanthopagrus schlegeli) juvenile. Five isonitrogenic and isolipidic diets were prepared with levels of 0 (control), 80, 160, 240 and 320 g kg^?1 FSM. Triplicate groups (40 fish per tank) of juvenile black sea bream with initial weight of 1.17 ± 0.04 g were hand‐fed to visual satiation at three meals per day for 8 weeks. The fish fed diets containing different levels of FSM had no significant differences regarding survival and specific growth rate compared with control group. Feed and protein efficiency ratios of fish fed diet containing 320 g kg^?1 FSM were significantly lower than those of control group. Daily feed intake and daily protein intake of fish fed diet containing 240–320 g kg^?1 were significantly higher than those of control group. Hepatosomatic index and condition factor of fish were not affected by different dietary FSM level. Fish fed diets containing 240–320 g kg^?1 FSM had significantly higher visceral somatic index than control group. Whole body proximate and amino acid compositions of fish were not affected by dietary FSM level. The activity of digestive enzymes in the intestine was not affected by dietary FSM level. The activity of glutathione peroxidase in liver was significantly higher for fish fed the diet containing 160 g kg^?1 FSM compared with control group. This study showed that up to 40% fish meal in the diets of juvenile black sea bream could be replaced by fermented soybean meal with supplementation of methionine, lysine and taurine.     

Acute toxicity of nitrite on white shrimp Litopenaeus vannamei (Boone) juveniles in low‐salinity water

The nitrite toxicity was estimated in juveniles of L. vannamei. The 24, 48, 72 and 96 h LC₅₀ of nitrite‐N on juveniles were 8.1, 7.9, 6.8 and 5.7 mg L^?1 at 0.6 g L^?1; 14.4, 9.6 8.3 and 7.0 mg L^?1 at 1.0 g L^?1; 19.4, 15.4, 13.4 and 12.4 mg L^?1 at 2.0 g L^?1 of salinity respectively. The tolerance of juveniles to nitrite decreased at 96 h of exposure by 18.6% and 54.0%, when salinity declined from 1.0 to 0.6 g L^?1 and from 2.0 to 0.6 g L^?1 respectively. The safe concentrations at salinities of 0.6, 1.0 and 2.0 g L^?1 were 0.28, 0.35 and 0.62 mg L^?1 nitrite‐N respectively. The relationship between LC₅₀ (mg L^?1), salinity (S) (g L^?1) and exposure time (T) (h) was LC₅₀ = 8.4688 + 5.6764S – 0.0762T for salinities from 0.6 to 2.0 g L^?1 and for exposure times from 24 to 96 h; the relationship between survival (%) and nitrite‐N concentration (C) for salinity of 0.6–2.0 g L^?1, nitrite‐N concentrations of 0–40 mg L^?1 and exposure times from 0 to 96 h was as follows: survival (%) = 0.8442 + 0.1909S – 0.0038T – 0.0277C + 0.0008ST + 0.0001CT–0.0029SC, and the tentative equation for predicting the 96‐h LC₅₀ to salinities from 0.6 to 35 g L^?1 in L. vannamei juveniles (3.9–4.4 g) was 96‐h LC₅₀ = 0.2127 S² + 1.558S + 5.9868. For nitrite toxicity, it is shown that a small change in salinity of waters from 2.0 to 0.6 g L^?1 is more critical for L. vannamei than when wider differences in salinity occur in brackish and marine waters (15–35 g L^?1).     

Effects of acute change in salinity and moulting on the infection of white leg shrimp (Penaeus vannamei) with white spot syndrome virus upon immersion challenge

In the field, moulting and salinity drop in the water due to excessive rainfall have been mentioned to be risk factors for WSSV outbreaks. Therefore, in this study, the effect of an acute change in environmental salinity and shedding of the old cuticle shell on the susceptibility of Penaeus vannamei to WSSV was evaluated by immersion challenge. For testing the effect of abrupt salinity stress, early premoult shrimp that were acclimated to 35 g L^?1 were subjected to salinities of 50 g L^?1, 35 g L^?1, 20 g L^?1, 10 g L^?1 and 7 g L^?1 or 5 g L^?1 and simultaneously exposed to 10^5.5 SID₅₀ mL^?1 of WSSV for 5 h, after which the salinity was brought back to 35 g L^?1. Shrimp that were transferred from 35 g L^?1 to 50 g L^?1, 35 g L^?1 and 20 g L^?1 did not become infected with WSSV. Shrimp became infected with WSSV after an acute salinity drop from 35 g L^?1 to 10 g L^?1 and lower. The mortality in shrimp, subjected to a salinity change to 10 g L^?1, 7 g L^?1 and 5 g L^?1, was 6.7%, 46.7% and 53.3%, respectively (P < 0.05)_. For testing the effect of moulting, shrimp in early premoult, moulting and post‐moult were immersed in sea water containing 10^5.5 SID₅₀ mL^?1 of WSSV. The resulting mortality due to WSSV infection in shrimp inoculated during early premoult (0%), ecdysis (53.3%) and post‐moult (26.72%) demonstrated that a significant difference exists in susceptibility of shrimp during the short moulting process (P < 0.05). The findings of this study indicate that during a drop in environmental salinity lower than 10 g L^?1 and ecdysis, shrimp are at risk for a WSSV infection. These findings have important implications for WSSV control measures.     

Dietary protein requirement of zebra sea bream (Diplodus cervinus,Lowe 1838) juveniles

A 14 weeks growth trial was performed to estimate the protein requirement for growth and maintenance of zebra sea bream (Diplodus cervinus) juveniles. For that purpose, nine isolipidic diets were formulated to contain increasing protein levels (from 50 to 550 g kg^?1) at the expense of carbohydrate. Each diet was assigned to duplicate groups of 20 fish, with an average body weight of 7.7 g. Feed efficiency improved with dietary protein up to 400 g kg^?1, no further differences being noticed at higher protein levels. Fish fed the 50 g kg^?1 protein diet lost weight during the trial. In the other groups, weight gain improved as dietary protein increased up to 350–400 g kg^?1. Fish fed diets with 250 g kg^?1 protein or lower had lower whole‐body protein content than the other groups. A curvilinear‐plateau model was used to adjust weight gain and protein gain (g kg ABW^?1 day^?1) to dietary protein levels. Based on that model, the optimum dietary protein requirement for maximum weight gain was estimated to be 437.6 g kg^?1 and for maximum protein gain 461.9 g kg^?1, corresponding to a protein intake of 7.63 g kg ABW^?1 day^?1. Protein requirement for maintenance was estimated to be 1.01 g kg ABW^?1 day^?1.     

Utilization of dietary starch by juvenile white sea bream Diplodus sargus at different feeding frequencies

To assess the effect of feeding frequency on the utilization of dietary starch by white sea bream juveniles, triplicate groups of fish were fed an experimental diet (400 g kg^?1 protein, 140 g kg^?1 lipids and 350 g kg^?1 pregelatinized maize starch) to apparent visual satiation 2, 3 or 4 times a day for 63 days. Growth performance, feed utilization efficiency, glycaemia, cholesterolaemia, plasma triacylglycerides, liver lipids and glycogen content were unaffected by feeding frequency. α‐Amylase activity increased from the pyloric caeca to the posterior intestine and was higher in fish fed twice a day than in fish fed 3 or 4 times a day. Hepatic glucokinase (GK) activity decreased with the increase in feeding frequencies, whereas fructose‐1,6‐bisphosphatase (FBPase) activity increased. Hepatic glucose‐6‐phosphate dehydrogenase and glutamate dehydrogenase activities were unaffected by feeding frequency. Overall, feeding frequency did not improve white sea bream dietary starch utilization. α‐Amylase, GK and FBPase activities responded to dietary starch consumed at each meal, denoting a good metabolic adaptation of the fish to the feeding conditions.     

Inclusion of camelina meal as a protein source in diets for farmed salmonids

Camelina meal (Camelina sativa) (CM) is a potential protein source for aquaculture feeds, on account of its crude protein level (380 g kg^?1) and inclusion of most indispensable amino acids. Two experiments were conducted with rainbow trout (Oncorhynchus mykiss) and Atlantic salmon (Salmo salar). Rainbow trout (44.9 g fish^?1) were fed diets with CM at 0 g kg^?1 (0% CM), 70 g kg^?1 (7% CM), 140 g kg^?1 (14% CM) or 210 g kg^?1 (21% CM) for 12 weeks at 14 °C in freshwater, and salmon (241.8 g fish^?1) were fed diets with CM at 0 g kg^?1 (0% CM), 80 g kg^?1 (8% CM), 160 g kg^?1 (16% CM) or 240 g kg^?1 (24% CM) for 16 weeks at 14 °C in sea water. Growth, lipid and amino acid tissue compositions were compared between species. Trout could tolerate up to 14% CM diets without affecting the growth compared to the control, while salmon fed ≥8% CM gained less weight than the control (P = 0.008). The feed conversion ratio in trout fed 21% CM was higher than the control (P = 0.002), and feed intake in salmon fed ≥8% CM was lower than the control (P = 0.006). Trout fatty acid and amino acid composition showed minimal differences between CM‐fed and control‐fed fish, while salmon showed significant alterations after feeding CM diets. Multivariate analyses emphasized differences in tissue composition between species fed CM diets.     

Biochemical parameters in the blood of gilthead sea bream (Sparus aurata Linnaeus, 1758) supplemented with commercially available β‐glucan‐based product (IMUNO‐2865®)

The aim of this study was to evaluate the effects of a promising new immune stimulant in aquaculture (IMUNO‐2865^®) on biochemical parameters in sea bream during the winter stress period. A total of 640 sea bream were fed throughout 90 days with diets containing 0 (Group 1), 1 (Group 2), 10 (Group 3) and 25 g (Group 4) of IMUNO‐2865^® kg^?1 of feed. Samples were taken each month and 90 days after supplementation. No statistical differences among treatment groups were noticed for the following biochemical parameters: glucose (GLU), aspartate aminotransferase (AST), plasma cholesterol (CHOL), lactate dehydrogenase (LDH), urea (URE) and creatinine (CREA). At the final sampling, total ammonia (NH₃) was higher in Groups 3 and 4 compared to the control and the low supplementation group (p < .05), while total proteins (TP) was significantly higher in Group 4 compared to all other groups, and in Groups 2 and 3 compared to the control group (p < .05). Blood Ca⁺⁺ levels were significantly higher after 60 days of feeding in all treatment groups compared to the control, and remained elevated in Group 4 even after 90 days following cessation of supplementation (p < .05). The results of this study described the increase of biochemical parameters in the blood of sea bream after use of IMUNO‐2865^® but future research is needed to evaluate its potentially immunostimulative effect on fish in commercial aquaculture.     

Energy budget adjustment of sea cucumber Apostichopus japonicus during breeding period

Reproductive success is unpredictable for many cultured echinoderms. And cost of reproduction plays an important role in animal life‐history. Therefore, understanding cost of reproduction contributes to improving breeding techniques during broodstock rearing in aquaculture. In this study, energetic costs during breeding were explored in the sea cucumber, Apostichopus japonicus, an important aquaculture species in China, Japan and South Korea. The food intake, digestive functions and energy budget patterns were estimated at different breeding stages. Unexpectedly, in the growing gonad phase of the sea cucumber lifecycle, animals showed a decline in feed consumption (from 4.49 to 2.6 g ind^?1 day^?1), ingestion rate (from 0.4 to 0.13 g g^?1 day^?1) and apparent digestive rate (from 14.73% to 10.92%), resulting in a reduced energy input. In addition, the increased energy investment in reproduction (from 1.76% to 15.61%) resulted in a decrease in energy allocated to soma growth (from 17.1% to 5.64%) and self‐maintenance (from 47.82% to 34.67%). These results suggest that reproduction impairs energy acquisition ability in breeding A. japonicus. And broodstock can adapt energy shortage by internal adjustment of energy allocation strategy.     

The kinetic profile of oxolinic acid in sharpsnout sea bream, Diplodus puntazzo (Cetti 1777)

The pharmacokinetics of oxolinic acid (OA) were investigated after a single intra‐vascular injection (20 mg kg^?1 fish) in sharpsnout sea bream (90 g), a promising new euryhaline species for Mediterranean fish farming. The distribution half‐life (t_1/2α) and the elimination half‐life (t_1/2β) of OA were calculated to be 0.4 and 10 h respectively. The apparent volume of distribution at steady‐state (V_d(ss)) and total clearance rate (CL_T) of the drug were found to be 2.1 L kg and 0.2 L kg^?1 h^?1 respectively. The bioavailability (F%) of OA following oral administration (40 mg kg^?1 fish) was estimated to be 15%. The results indicate a rapid distribution and elimination of the drug, moderate tissue penetration, but low absorption in sharpsnout sea bream. The kinetic profile of OA found in this species is comparable with that observed in another well‐known sparid, gilthead sea bream.     

Co‐culture of sea cucumber Holothuria scabra and red seaweed Kappaphycus striatum

Commercially valuable sea cucumbers are potential co‐culture species in tropical lagoon environments, where they may be integrated into established aquaculture areas used for seaweed farming. In the current study, wild‐caught juvenile sea cucumbers, Holothuria scabra, and red seaweed Kappaphycus striatum were co‐cultured on Zanzibar, United Republic of Tanzania. Sea cucumbers (97 g ± 31 SD, n = 52) were cultured in mesh enclosures at initial cage stocking densities of 124 ± 21 SD and 218 ± 16 SD g m^?2 under seaweed culture lines. Over 83 days, individual growth rate (1.6 g d^?1 ± 0.2 SD) of sea cucumbers at low stocking density was significantly higher (χ² = 8.292, d.f. = 1, P = 0.004) than at high‐stocking density (0.9 g d^?1 ± 0.1 SD). Seaweed individual growth rates [6.27 (±0.3 SE) g d^?1] were highest in co‐culture with sea cucumber at low density but did not differ significantly from high sea cucumber density or seaweed monoculture treatments (χ² = 3.0885, d.f. = 2, P = 0.2135). Seaweed growth varied significantly (χ² = 35.6, d.f. = 2, P < 0.0001) with sampling period, with the final sampling period resulting in the highest growth rate. Growth performance for seaweed and sea cucumbers (χ² = 3.089, d.f. = 2, P = 0.21 and χ² = 0.08, d.f. = 1, P = 0.777 respectively), did not differ significantly between monoculture and co‐culture treatments, yet growth in co‐culture was comparable with that reported for existing commercial monoculture. Results indicate H. scabra is a highly viable candidate species for lagoon co‐culture with seaweed. Co‐culture offers a more efficient use of limited coastal space over monoculture and is recommended as a potential coastal livelihood option for lagoon farmers in tropical regions.     

An optimized and simplified method for analysing urea and ammonia in freshwater aquaculture systems

This study presents a simple urease method for analysis of ammonia and urea in freshwater aquaculture systems. Urea is hydrolysed into ammonia using urease followed by analysis of released ammonia using the salicylate‐hypochlorite method. The hydrolysis of urea is performed at room temperature and without addition of a buffer. A number of tests were performed on water samples obtained from a commercial rainbow trout farm to determine the optimal urease concentration and time for complete hydrolysis. One mL of water sample was spiked with 1.3 mL urea at three different concentrations: 50 μg L^?1, 100 μg L^?1 and 200 μg L^?1 urea‐N. In addition, five concentrations of urease were tested, ranging from 0.1 U mL^?1 to 4 U mL^?1. Samples were hydrolysed for various time periods ranging from 5 to 120 min. A urease concentration of 0.4 UmL^?1 and a hydrolysis period of 120 min gave the best results, with 99.6–101% recovery of urea‐N in samples spiked with 100 or 200 μg L^?1 urea‐N. The level of accurate quantification of ammonia using the method is 50 μg L^?1 NH₄⁺‐N, and the detection level is 5–10 μg L^?1 NH₄⁺‐N.     

Effects of salinity on standard metabolic rate of juvenile marbled spinefoot (Siganus rivulatus)

Marbled spinefoot, Siganus rivulatus, is a herbivorous euryhaline teleost widely distributed in the Eastern Mediterranean. It is an economically valuable species and a suitable candidate for warm water aquaculture. Accordingly, understanding the effects of environmental factors on fish metabolism is important to optimize culture conditions. Two experiments were performed to establish standard metabolic rate and study the effect of salinity on metabolism of marbled spinefoot. In the first experiment, a series of flow‐through respirometry experiments was performed at 27°C and 35 g L^?1. The standard metabolic rate of marbled spinefoot juveniles was calculated as 0.57 ± 0.02 mg O₂ g^?1 h^?1 (mean ± SE). In the second experiment, fish were maintained at salinities of 25, 30, 35 and 40 g L^?1 for 2 weeks. Flow‐through respirometry was performed to measure respiration rates at the various salinities. Respiration rates were similar among fish in salinities of 30, 35 and 40 g L^?1 but increased significantly at 25 g L^?1. Results suggest that despite the euryhalinity of marbled spinefoot, farmers should maintain salinity within the optimal range of 30–40 g L^?1 in order to improve productivity.     

Larval development and salinity tolerance of Japanese flounder (Paralichthys olivaceus) from hatching to juvenile settlement

Salinity tolerance and growth of Japanese flounder Paralichthys olivaceus at different developmental stages were evaluated, including newly hatched larvae (nhl), yolk sac larvae (ysl), oil droplet larvae (odl), post oil droplet larvae (podl), premetamorphic larvae (preml) and prometamorphic larvae (proml), at 11 salinities from 5 to 55 g L^?1 for 96 h. The ontogenesis during the early life of P. olivaceus was investigated under hatchery salinity 35 g L^?1. The results showed that suitable salinities for nhl, ysl, odl, podl, preml and proml larvae were 10 to 25 g L^?1, 10 to 30 g L^?1, 20 to 30 g L^?1, 30 g L^?1, 10 to 30 g L^?1, 15 g L^?1, respectively, demonstrating an ontogenetic variation of salinity tolerance. The salinity tolerance of nhl, ysl, preml was higher than that of odl, podl and proml. The ysl and preml larvae displayed wide salinity tolerances. The present findings demonstrate that the suitable salinity for larviculture of P. olivaceus is 20–25 g L^?1 before the depletion of oil droplet; after that, higher salinity (30 g L^?1) should be ensured for the post‐oil droplet larvae; the premetamorphic larvae can be cultured at a wide salinity range (10–30 g L^?1), and the metamorphosed larvae should be reared at salinity about 15 g L^?1.     

Effects of dietary mannan oligosaccharides on growth,body composition and intestine of the sea bass (Dicentrarchus labrax L.)

The effect of Bio‐Mos incorporated into feed formulation on the growth, feed utilization, body composition and histological response of sea bass (Dicentrarchus labrax) was investigated. Final fish weight, feed conversion ratio (FCR), specific growth rate (SGR), protein efficiency ratio (PER), protein productive value (PPV) and energy utilization (EU) of sea bass feed Bio‐Mos supplemented diet and the control diet were determined at the end of experiment. Data present mean ± SD from triplicate determination (n = 3) for a 75‐day feeding trial. Different concentrations (0.5, 1.0, 2.0. 3.0 and 4.0 g kg diet^?1) of Bio‐Mos supplementation and a control without Bio‐Mos incorporation were fed to the fish, feed in the form of dry diets. Average final weight was significantly higher at 1.0 g kg diet^?1 of Bio‐Mos and lowest in control fish group; SGR significantly higher at the 1.0 g kg diet^?1 of Bio‐Mos. In addition,, PER, PPV and EU showed the same trend. The chemical body composition, crude protein, dry matter, crude fat and ash were significant (P ≤ 0.01) compared to control groups. We concluded that 1.0 g kg diet^?1 of Bio‐Mos improved the growth, feed efficiency, histology intestine and survival of sea bass.     

Effects of dietary carbohydrate on weight gain and gonad production in small sea urchins,Lytechinus variegatus

In experiment 1, juvenile sea urchins (n = 80, 0.088 ± 0.001 g wet weight and 5.72 ± 0.04 mm diameter) were held individually and fed ad libitum one of three semi‐purified formulated diets (n = 16 individuals treatment^?1). In the diets, protein was held constant (310 g kg^?1 dry, as fed) and carbohydrate level varied (190, 260, or 380 g kg^?1 dry, as fed). Wet weights were measured every 2 weeks. Total wet weight gain was inversely proportional to dietary carbohydrate level and energy content of the respective diet. In experiment 2, sea urchins (5.60 ± 0.48 g wet weight, n = 40) fed 190 g kg^?1 carbohydrate consumed significantly more dry feed than those fed 260 g kg^?1, but not more than those fed 380 g kg^?1 carbohydrate. Based on differential feed intake rates, sea urchins that consumed more feed also consumed higher levels of protein and had the highest weight gain. Consequently, protein content and/or protein: energy ratio may be important in determining feed utilization and growth among sea urchins in this study. The average digestible energy intake was approximately 70 kcal kg^?1 body weight day^?1, suggesting daily caloric intake of juvenile Lytechinus variegatus is lower than in shrimp and fish.