Influence of dietary nucleotides supplementation on growth,body composition and fatty acid profile of Beluga sturgeon juveniles (Huso huso)

Effect of different levels (0%, 0.15%, 0.25%, 0.35% and 0.50%) of Optimûn, a commercial nucleotide (NT) product, on the growth performance, body composition and fatty acid profile of juvenile Beluga sturgeon (Huso huso) (12.57 ± 0.5 g) was investigated over a 62‐day period. This experiment was done in fifteen 600 L tanks, each stocked with 30 fish. Fish fed nucleotide showed significantly better growth performance (P < 0.05). Incorporation of 0.25% and 0.35% NT resulted in whole body protein content elevation, but the other proximate composition indices were not influenced by dietary nucleotide treatments. There were significant differences in saturated fatty acids (SFA) and total unsaturated fatty acids (TUFA) levels among fish fed on different experimental diets, while monounsaturated fatty acids, polyunsaturated fatty acids (PUFA), n‐3 PUFA, n‐6 PUFA, n3/n6 and eicosapentaenoic acid + docosahexaenoic acid were not influenced by NT. The results showed that diet supplementation with 0.35% Optimûn (NT) enhance growth performance, also administration of 0.25% and 0.35% affected chemical composition, as well as decreased SFA/TUFA ratio of Beluga juvenile.     

Effect of dietary supplementation of brewers yeast and nucleotide singularly on growth,survival and vibriosis resistance on juveniles of the gastropod spotted babylon (<Emphasis Type="Italic">Babylonia areolata</Emphasis>)

This study was undertaken to evaluate the use of brewers yeast and nucleotides as a growth promoter and to provide vibriosis resistance for the juveniles of gastropod spotted babylon (Babylonia areolata). Juvenile spotted babylon (0.3 g initial weight) were randomly distributed at a density of 50 snails in 45-L aquaria and fed a basic diet (40% crude protein) containing two incremental levels of 1 and 2% brewers yeast and nucleotides singularly for 4 months. After the feeding trial, snails from each treatment were challenged by pathogenic bacteria Vibrio alginolyticus given by intramuscular injection and kept under observation for 5 days to record clinical signs and daily mortality rates. Results indicated that the snails fed with diets supplemented with brewers yeast or nucleotides exhibited significantly greater growth than those fed the basic diet (P < 0.05) and significantly better food conversion ratios compared to snails fed the basic diet (P < 0.05). These results indicated that dietary supplementation of brewers yeast or nucleotides, at least at the tested dosages, enhanced spotted babylon growth. Supplementing the diet with 1% brewers yeast promises to provide appropriate resistance to V. alginolyticus.     

Dietary nucleotide supplements influence the growth,haemato‐immunological parameters and stress responses in endangered Caspian brown trout (Salmo trutta caspius Kessler, 1877)

A feeding trial was conducted to evaluate the effects of Optimûn, a commercial nucleotide (NT) product, on the growth, haemato‐immunological and serum biochemical parameters and stress responses of Caspian brown trout fingerlings (average initial weight of 12.26 g). A basal diet was supplemented with levels of 0 (control), 1.5, 2.5, 3.5 and 5 g NT kg^?1 to formulate five experimental diets. After 8 weeks of feeding trial, fish fed diet with 2.5 g NT kg^?1 had the highest final weight compared with other treatments. The fish fed diets with 2.5 g NT kg^?1 had higher blood protein, albumin, albumin/globulin ratio, red blood cells, white blood cells and lymphocyte content and lower alkaline phosphatase. The lysozyme activity in serum was found to be significantly (P < 0.05) greater in fish fed diet with 2.5 g NT kg^?1. Concerning both stressors (confinement and salinity stress), fish fed diet with 2.5 g NT kg^?1 had lower plasma cortisol and glucose levels. Thus, administration of 2.5 g kg^?1 of the Optimûn dietary nucleotide formula is recommended to promote growth and immunity as well as to enhance stress responses of Caspian brown trout.     

Effects of inorganic and organic dietary copper supplementation on growth performance and tissue composition for juvenile red drum (Sciaenops ocellatus L.)

A feeding trial was conducted to evaluate the dietary copper requirement of red drum (Sciaenops ocellatus) and compare the bioavailability of copper sulphate (CuSO₄) and copper‐ethanolamine. A basal diet was formulated using semi‐purified ingredients and analysed to contain 3 mg Cu/kg. Both copper sources were supplemented to the basal diet at either 5, 10 or 20 mg Cu/kg of dry diet. No significant differences were observed in growth performance of fish fed the various diets. However, red drum fed all copper‐supplemented diets retained more copper in liver and whole‐body tissues compared to fish fed the basal diet. Within both inorganic and organic copper treatments, the highest tissue copper concentrations were observed in fish fed diets supplemented with 10 mg Cu/kg. No significant differences were detected in net copper retention regardless of the nature of the copper source; hence, the bioavailability of copper sulphate and copper‐ethanolamine complex was not different in the diets for juvenile red drum. Furthermore, the minimum copper requirement for growth performance of juvenile red drum appeared to be satisfied when fish were fed the basal diet containing 3 mg Cu/kg diet, and no detrimental effects were observed in red drum fed diets supplemented with 20 mg Cu/kg.     

Effects of prebiotics on nutrient digestibility of a soybean‐meal‐based diet by red drum Sciaenops ocellatus (Linnaeus)

The present study examined the effects of four prebiotic compounds on nutrient and energy digestibility of soybean‐meal‐based diets by red drum (Sciaenops ocellatus). The experimental diets contained 40% crude protein of which approximately half was provided by soybean meal with the remainder from menhaden fish meal. The four prebiotics GroBiotic^®‐A (a mixture of partially autolysed brewers yeast, dairy ingredient components and dried fermentation products), mannanoligosaccharide (MOS), galacto‐oligosaccharide (GOS) and inulin were individually added to the basal diet at 1% by weight. A diet with all its protein provided by menhaden fish meal was also included as a control. This control diet had the highest apparent digestibility coefficient (ADC) values – 87% for protein, 87% for lipid, 78% for organic matter and 83% for energy. The basal soybean‐meal‐based diet supplemented with GroBiotic^®‐A, GOS and MOS had significantly (P<0.05) increased protein (82%, 82%, 82% respectively) and organic matter ADC values (69%, 64%, 66% respectively), compared with the basal diet (69% for protein and 49% for organic matter). However, the lipid ADC values were significantly decreased for fish fed with the diets supplemented with inulin, GOS and MOS (63%, 61%, 61% respectively) compared with the basal diet (77%) but not for those fed GroBiotic^®‐A (82%). Energy ADC values were also increased in fish fed with the GroBiotic‐A^®, GOS and MOS diets (73%, 70%, 72%), compared with the basal diet (57%); however, fish fed with the inulin diet had an energy ADC value (54%) similar to that of fish fed with the basal diet. Thus, the present study is the first to demonstrate that nutrient and energy digestibility of soybean‐meal‐based diets by red drum can be enhanced with prebiotic supplementation.     

Growth,nitrogen gain and indispensable amino acid retention of pacu (Piaractus mesopotamicus,Holmberg 1887) fed different brewers yeast (Saccharomyces cerevisiae) levels

A feeding‐and‐digestibility trials were carried out to evaluate the efficacy of replacing fishmeal with brewers yeast Saccharomyces cerevisiae in diets of pacu, Piaractus mesopotamicus, juveniles. The feeding trial was conducted during 54 days with 450 fish (26.6 ± 1.7 g) testing six isonitrogenous (270 g kg^?1 crude protein) and isoenergetic (19 MJ kg^?1 crude energy) diets, with increasing yeast level to replace 0 (control), 30, 35, 50, 70 or 100% of dietary fishmeal. Growth performance and feed utilization increased with increasing dietary yeast level until 50% fishmeal replacement. Protein retention efficiency was higher in fish fed 35 and 50%. Protein digestibility and the fillet hue (the red/green chromaticity) were not significantly different among all treatments. Nitrogen gains were significantly improved in fish fed 35% replacement diet compared to fish fed the control diet. The retentions of indispensable amino acids tended to increase with increasing dietary yeast levels, with maximum retention at 35–50%. On the basis of our results, replacing 50% fishmeal by yeast in pacu diets successfully improved feed efficiency and growth performance, and reduced nitrogen losses, thereby reducing the nitrogen outputs from fish farms.     

Evaluation of dietary creatine and guanidinoacetic acid supplementation in juvenile red drum Sciaenops ocellatus

Two separate comparative feeding trials were conducted to evaluate if supplemental dietary guanidinoacetic acid (GDA), either singly or in combination with creatine, could enhance growth performance of red drum. The basal diet for both trials was formulated with practical ingredients but was not supplemented with creatine or GDA. For the experimental diets, creatine (0 or 20 g/kg) and GDA (0, 5 or 10 g/kg) were added to the basal diet in a 2 × 3 factorial arrangement for trial 1. Another 2 × 3 experimental design was adopted in trial 2 to further evaluate creatine (0 or 20 g/kg) and GDA (0, 10 or 20 g/kg) supplementation. Each diet was fed to juvenile red drum in either quadruplicate (trial 1) or triplicate (trial 2) aquaria twice daily for a total of 8 weeks. After each feeding trial, fish were sampled for body condition indices and whole‐body composition analysis, as well as determination of plasma, liver and muscle creatine concentrations. In trial 1, dietary creatine supplementation alone significantly (p < .05) improved weight gain and feed efficiency of red drum. An interaction between creatine and GDA was seen in whole‐body protein and lipid in the two trials. In trial 1, the highest levels of whole‐body protein and lipid were observed in fish fed 10 g GDA/kg, and in trial 2, supplementation of the diet with 10 g GDA/kg increased muscle protein and muscle lipid although there was a trending decline in fish fed the 20 g/kg GDA‐supplemented diet. In both trials of the present study, dietary GDA significantly (p < .05) enhanced liver creatine content. Dietary creatine also significantly (p < .05) enhanced plasma and muscle creatine content of red drum. Based on the results of this study, creatine was effective in enhancing weight gain and feed efficiency of red drum as seen in previous studies; however, GDA was not effective in influencing growth performance but limited synthesis of creatine from dietary GDA was apparent.     

Evaluation of Growth Performance and Whole-body Composition of Juvenile Hybrid Striped Bass Morone chrysops × Morone saxatilis and Red Drum Sciaenops ocellatus Fed High-protein and High-lipid Diets

To investigate potential use of increasing nutritional density of diets for rapid growth of warm‐water fishes, a feeding trial was conducted in which growth performance, body indexes, and whole‐body composition of juvenile hybrid striped bass fed diets comprising protein (49, 54, and 59%), lipid (16, 20, 23, and 28%), and energy (22.0–25.1 kJ/g) concentrations beyond established minimum levels were compared to those of fish fed a more typical commercial reference diet (37.5% crude protein, 10.5% crude lipid, and 19.6 kJ/g energy on a dry matter basis). A subset of the experimental diets and the commercial reference diet also were fed to juvenile red drum. After 6 wk of feeding, hybrid striped bass fed the high‐protein and high‐lipid diets showed much greater growth performance compared to fish fed the commercial diet. Increasing dietary protein level, but not lipid level, tended (P ≤ 0.1) to enhance weight gain and feed efficiency of hybrid striped bass. Hepatosomatic index (HSI), intraperitoneal fat (IPF) ratio, and whole‐body protein were significantly (P < 0.01) influenced by dietary protein level. The dietary lipid and associated energy level had significant negative linear effects on daily feed intake. Linear regression analysis showed that dietary energy : protein ratio, largely influenced by dietary protein level, moderately but significantly influenced weight gain, HSI, IPF ratio, and whole‐body protein of hybrid striped bass and red drum. Red drum grew very similar to hybrid striped bass in response to the experimental diets. However, significant differences in HSI, IPF ratio, whole‐body protein, lipid, moisture, and ash between hybrid striped bass and red drum were observed, indicating species differences in protein and energy partitioning. In particular, the excessive lipid in the diet increased HSI and whole‐body lipid of red drum but not of hybrid striped bass.     

Effects of dietary live yeast Debaryomyces hansenii on the immune and antioxidant system in juvenile leopard grouper Mycteroperca rosacea exposed to stress

This study investigated the effects of the dietary intake of live yeast Debaryomyces hansenii (CBS 8339) on the immune response of juvenile leopard groupers Mycteroperca rosacea and on their resistance to infection by dinoflagellates Amyloodinium ocellatum.During 4 weeks, juvenile groupers were fed either a diet supplemented with D. hansenii at 10⁶ cfu g^− 1 or a control diet. Both groups were then transferred to a system infected with A. ocellatum and maintained in this stressful environment, for one week. Rearing conditions were favorable to the proliferation of the dinoflagellate and, at 7 days post-infection, the cumulative mortality rate of the control group was 89.5%, suggesting that the yeast-enriched diet conferred protection against the parasite. Only fish with yeast-supplemented diet recovered from the A. ocellatum challenge.The immunological response of both groups of fish was evaluated. Samples were collected at weeks 4 (stressed fish) and 7 (recovering fish) to determine the levels of hemoglobin, plasmatic protein, and immunoglobulin M (IgM) as well as the activity of antioxidant enzymes (SOD and CAT). IgM increased significantly (P ≤ 0.05) in the recovering fish, which had all been fed the yeast diet. A significantly increase was also observed in superoxide dismutase activity in juvenile fish fed the yeast diet; however catalase activity was not affected by the dietary yeast supplement. Overall, fish that received the yeast supplement in their diet have an enhanced immune response as compared with their control counterparts. The present results show that a diet supplemented with D. hansenii stimulates the immune system of juvenile M. rosacea thus enhancing their resistance against A. ocellatum.     

Evaluation of fisheries by-catch and by-product meals in diets for red drum Sciaenops ocellatus L.

This study evaluated various by‐catch and by‐product meals of marine origin with red drum (Sciaenops ocellatus L.). Four different kinds of by‐catch or by‐product meals [shrimp by‐catch meal from shrimp trawling, Pacific white shrimp (Litopenaeus vannamei (Boone)) processing waste meal, red salmon (Oncorhynchus nerka (Walbaum)) head meal, and Pacific whiting (Merluccius productus (Ayres)) meal] were substituted for Special Select? menhaden fish meal at 33% or 67% of crude protein in diets formulated to contain 40% crude protein, 12% lipid, and 14.6 kJ digestible energy g^?1. Each of these diets and three additional diets consisting of shrimp processing waste meal formulated on a digestible‐protein basis and two Pacific whiting diets containing reduced levels of ash were also evaluated in two 6‐week feeding trials with juvenile red drum (initial weight of 4–5 and 1–2 g fish^?1 in trials 1 and 2). Red drum fed by‐catch meal at either level of substitution performed as well as fish fed the control diet; whereas, fish fed shrimp processing waste meal diets had significantly (P≤0.05) reduced weight gain and feed efficiency ratio values compared with the controls, even when fed on a digestible‐protein basis. The diets containing Pacific whiting at either levels of substitution and regardless of ash level supported similar performance of red drum as those fed the control diet. Fish fed the red salmon head meal diet fared poorly, probably owing to an excessive amount of lipid in the diet that became rancid. Overall, by‐catch meal associated with shrimp trawling and Pacific whiting appear to be suitable protein feedstuffs for red drum.     

Effects of the Prebiotics GroBiotic®‐A and Inulin on the Intestinal Microbiota of Red Drum,Sciaenops ocellatus

Two separate feeding trials examined the effects of dietary supplementation of the prebiotics GroBiotic^®‐A and inulin on growth performance and gastrointestinal tract microbiota of the red drum, Sciaenops ocellatus. In the first feeding trial, fish meal‐based diets without prebiotics or supplemented with either GroBiotic^®‐A or inulin at 1% of dry weight were fed to triplicate groups of juvenile red drum (initial weight of 2.6 g) in 110‐L aquaria operated as a brackish water (7 ppt) recirculating system for 8 wk. In the second feeding trial, soybean meal/fish meal‐based diets supplemented with either GroBiotic^®‐A or inulin at 1% of dry weight were fed to triplicate groups of red drum (initial weight of 15.8 g) in 110‐L aquaria operated as either a common recirculating water system or closed system with individual biofilters (independent aquaria) for 6 wk. Supplementation of the prebiotics in either feeding trial did not alter weight gain, feed efficiency ratio, or protein efficiency ratio of red drum fed the various diets. In the second feeding trial, the culture system significantly affected weight gain, feed efficiency ratio, and protein efficiency ratio although there were no effects of dietary treatments on fish performance or whole‐body protein, lipid, moisture, or ash. Denaturing gradient gel electrophoresis (DGGE) analysis of the gastrointestinal tract microbial community showed no effect of the dietary prebiotics as the microbial community appeared to be dominated by a single organism with very low diversity when compared with other livestock and fish species. DGGE of the microbial community in the biofilters of the independent aquariums showed a diverse microbial community that was not affected by the dietary prebiotics.     

Effect of nucleotides supplementation to low‐fish meal feed on long‐chain polyunsaturated fatty acid composition of juvenile rainbow trout Oncorhynchus mykiss

A feeding trial was conducted to evaluate the effect of nucleotides supplementation to low‐fish meal feed on growth and fatty acid composition of rainbow trout. Six isonitrogenous (42% crude protein) and isolipidic (18% crude lipid) diets were formulated containing fish meal and plant ingredients as main protein sources. The control diet was a basal diet without supplementation of nucleotides, and five experimental diets were prepared by supplementing one of the five different nucleotides in the form of 5′‐monophosphate (0.15%), that is inosine (IMP), adenosine (AMP), guanosine (GMP), uridine (UMP) and cytidine (CMP) onto basal diet. Two hundred forty juvenile rainbow trout with an initial average body weight 9.8 g were randomly distributed into twelve aquaria. After 15 weeks of feeding period, growth performance and feed utilization of rainbow trout were not significantly different among dietary treatments. Dietary GMP, UMP and CMP tended to accumulate crude lipid in the muscle and whole fish body. Moreover, dietary GMP, UMP and CMP significantly increased hepatic 18:3n‐3 and long‐chain homologue 18:4n‐3 and 20:4n‐3 contents. Hepatic 18:2n‐6 content showed also increase in fish fed GMP, UMP and CMP diets, but decreased in long‐chain homologue 20:3n‐6 and 20:4n‐6 contents. Decrease in 20:4n‐6, 20:5n‐3 and 22:6n‐3 contents was also found in the muscle of fish fed IMP, GMP and CMP diets. The present study clearly showed that there was no positive effect of dietary nucleotides on growth of fish, but dietary nucleotides particularly GMP, UMP and CMP altered polyunsaturated fatty acid composition of rainbow trout.     

Combined effects of dietary mannan oligosaccharides and total fish oil substitution by soybean oil on European sea bass (Dicentrarchus labrax) juvenile diets

This study evaluates the effects of dietary mannan oligosaccharides (MOS) on growth, tissue composition, fatty acid profiles and liver morphology of European sea bass (Dicentrarchus labrax) fed diets containing either soybean oil (SBO; SBOMOS) or fish oil (FO; FOMOS) as unique oil source for 8 weeks. Results showed that MOS supplementation enhanced specific growth rate, regardless of the oil source used, and that dietary oil source reduced fish length, regardless of dietary MOS supplementation. Dietary MOS favoured lipid accumulation in muscle and anterior intestine when supplemented in FO‐based diets compared to fish fed SBO diet and reduces it in liver in relation to lower hepatocyte area, particularly in fish fed SBOMOS diet. Dietary MOS favoured liver and not muscular ∑n‐3 PUFA, DHA, EPA and ARA deposition, when combined with FO but not when included in SBO‐based diets. Thus, MOS dietary supplementation favours fish performance and helps to minimize the side effects derived from high dietary SBO supplementation on liver lipid accumulation and hepatocyte vacuolization, which could be of especial interest on long‐term feeding trials; however, the effects on favoured deposition ∑n‐3 PUFA are limited to FO‐based diets.     

Effects of dietary animal proteins on growth and body composition of the red drum (Sciaenops ocellatus)

Two experiments were conducted to determine the nutritional value of various dietary proteins for juvenile red drum. In the first 8-week feeding trial, diets containing similar quantities of lipid, carbohydrate, available energy and ash with 35% crude protein from either lyophilized whole-body croaker (Micropogon undulatus), striated beef muscle, red drum processing waste or commercially processed menhaden (Brevoortia tyrannus) fish meal were fed to juvenile red drum in brackish (6 ppt) water along with a control diet containing lyophilized muscle of red drum. The control diet produced significantly (P<0.05) greater weight gain (WG), feed efficiency (FE), and protein efficiency ratio (PER) values than all other diets; intermediate responses were observed for fish fed diets containing protein from red drum waste and whole-body croaker, while diets containing striated beef muscle and menhaden fish meal yielded the lowest values. Some differences in tissue indices and body composition of red drum including hepatosomatic index, whole-body ash and lipid, as well as liver lipid and glycogen were induced by the various diets. In the second 8-week feeding trial, the control diet containing red drum muscle was compared with similar diets containing protein from whole-body croaker and menhaden fish meal. Again the control diet produced the greatest WG, FE, and PER values followed by whole-body croaker and then menhaden fish meal. Effects of the dietary proteins on tissue indices and body composition were limited. The excellent protein quality and low-temperature processing of lyophilized red drum muscle resulted in superior performance of red drum relative to the other evaluated protein products, and lyophilized whole-body croaker provided better performance than commercially processed menhaden fish meal.     

Separate and combined effects of cyclic fasting and l‐carnitine supplementation in red porgy (Pagrus pagrus,L. 1758)

We examined the effects of cyclic fasting in red porgy (Pagrus pagrus) fed different dietary carnitine levels. Juvenile fish (23.58 ± 3.49 g) were divided into eight groups – four groups were fed every day to apparent satiation, while the other four were fasted for 7 days every 2 weeks. In each feeding regime, two replicates were fed an l ‐carnitine non‐supplemented diet (46 mg kg^?1) and the other two groups were fed an l ‐carnitine supplemented diet (630 mg kg^?1). Fish fed 630 mg l ‐carnitine accumulated two times more l ‐carnitine in muscle than fish fed 46 mg l ‐carnitine. Cyclic fasting reduced the growth performance and lipid content in the liver. Carnitine supplementation did not affect performance and body composition, but decreased the n‐6 PUFA content. Moreover, the combined effects of fasting and carnitine supplementation were observed on reducing the n‐3 fatty acid content. Areas of steatosis were found in the livers of red porgy, but the results revealed that supplementation of l ‐carnitine in cyclic fasted fish contributed towards a lower degree of vacuolization than in fish fed to apparent satiation. Regardless of the feeding regime applied, the spleen of fish fed the l ‐carnitine‐supplemented diet was haemorrhagic and hyper activation of melanomacrophage cells was observed.     

Nutrition of red drum,Sciaenops ocellatus L.: An additional evaluation of the effects of soya‐based diets and supplemental prebiotic

We assessed the effects of a fishmeal (FM)‐ and two soya‐based diets [without or with prebiotic (GroBiotic^® ‐A; GBA) supplementation] on the production performance, non‐specific immunity, blood parameters and gut microbiota diversity of red drum, Sciaenops ocellatus. All diets were formulated to contain 450 g/kg crude protein (CP) and 120 g/kg lipid. A combination of soya bean meal and soya protein concentrate (SP) was used to replace 88% of the FM in the FM‐based diet (REF) originating the first soya‐based diet (SOY). The second soya‐based diet (SOY + GBA) was designed identically to SOY except for the supplementation of GBA (20 g/kg) substituting for wheat flour. After feeding the experimental diets to triplicate groups of 25 (~3.4 g/fish) and 90 (~4.1 g/fish) red drum juveniles for 9 (Trial I) and 16 weeks (Trial II), our results showed that (i) red drum was highly sensitive to the soya‐based diets in the first week of feeding; (ii) replacing 88% of FM with SP reduced the production performance of red drum without affecting intestinal micromorphology; (iii) whole‐blood leucocyte oxidative radical production was unaffected while lower haematocrit and higher plasma lysozyme activity were found in fish fed REF; (iv) plasma osmolality was unaffected while lower glucose and higher lactate levels were observed in fish fed SOY and SOY + GBA; (v) 16S rRNA gene‐based diversity of fish gut microbiota was affected both by SP and by GBA. This study expands the information on red drum responses to soya‐based diets and prebiotic supplementation.     

Effect of dietary iron supplement on growth, haematology and microelements of juvenile grouper, Epinephelus coioides

An experiment was conducted to investigate the effect of dietary iron supplement on growth, haematology and microelements of juvenile grouper, Epinephelus coioides. Casein–gelatine‐based diets supplemented with 0, 50, 100, 150, 200 and 250 mg kg⁻¹ iron from ferrous sulphate were fed to grouper (mean initial weight: 21.0 ± 0.2 g) for 8 weeks. Weight gain was highest in fish fed the diet supplemented with 100 mg kg⁻¹ iron, intermediate in fish fed diets with 50, 150, 200 and 250 mg kg⁻¹ iron and lowest in fish fed the basal diet. Feed efficiency followed a similar trend except that the lowest value was in fish fed the basal diet and the diet supplemented with 250 mg kg⁻¹ iron. Hepatic iron was highest in fish fed diets supplemented with iron ≥100 mg kg⁻¹, followed by fish fed diet with 50 mg kg⁻¹ iron and lowest in fish fed the basal diet. The whole‐body iron was lowest in fish fed the basal diet but not significantly different from other groups, as judged by anova . Iron supplement to the basal diet had no significant effect on haematological parameters (red blood cell count, haematocrit and haemoglobin), hepatic copper concentration or manganese, zinc concentration in liver and whole body. Broken‐line analysis of hepatic iron indicated that iron supplementation of 100 mg kg⁻¹ satisfied the hepatic iron storage and that further supplementation did not expand the iron status.     

The Effects of Soybean Lecithin Supplementation to a Practical Diet Formulation on Juvenile Channel Catfish,Ictalurus punctatus: Growth,Survival, Hematology,Innate Immune Activity,and Lipid Biochemistry

A feeding trial was conducted to determine the effects of soy lecithin supplementation on production performance of juvenile channel catfish, Ictalurus punctatus (mean ± SE; 5.8 ± 0 g). The basal diet consisted of a practical dietary formulation for channel catfish, containing 4.3% endogenous phospholipids (PL) from dietary ingredients, to which supplemental PL from soybean lecithin were added. The study diets were 1 control and 2 experimental diets to which 0, 2, or 4% supplemental lecithin was added, respectively. Soy lecithin inclusion did not affect survival, growth, feed consumption, whole‐body total lipid, innate immune response, plasma cholesterol or triglyceride concentrations, or hepatosomatic index. Feed conversion (gain/intake) improved in fish fed 4% supplemental lecithin compared with 0% lecithin. Whole‐body crude protein was greater in fish fed 2% supplemental lecithin compared with 0% lecithin, while 4% supplemental lecithin was intermediate. Phosphatidylcholine (PC) content was greater in fish fed 2 or 4% lecithin than 0% lecithin. Plasma concentrations of PC were inversely proportional to dietary concentrations. Liver glycogen was greater in fish fed 0% lecithin compared with 2 or 4% lecithin. Liver lipid and phospholipid were lower in fish fed 0% lecithin than 2 or 4% lecithin. The dietary phospholipid requirement, if any, of juvenile channel catfish for growth and survival is less than or equal to 4.3% (1.5% PC) of the diet. Feed conversion is improved in channel catfish fed diets supplemented with 4% soy lecithin (7.2% phospholipid; 5.1% PC), which might offset additional costs due to phospholipid supplementation. Dietary soy lecithin inclusion altered plasma and liver lipid composition, but it is unknown whether these effects can alter the ability of juvenile catfish to survive and grow under various conditions.     

Dietary Supplementation of a Purified Nucleotide Mixture Transiently Enhanced Growth and Feed Utilization of Juvenile Red Drum, Sciaenops ocellatus

Abstract.— Commercial nucleotide products have been shown to enhance early growth as well as immunity and disease resistance in aquacultured fish. Thus, we investigated effects of a purified nucleotide mixture on growth and health of young red drum. The nucleotide premix, containing salts of cytidine, uridine, adenosine, and guanidine, was coated with binders, freeze-dried, and grounded to powder. A fish-meal-based diet was supplemented with 0.03, 0.1, or 0.3% by weight of the coated nucleotide mixture or with 0.2% Optimûn^® (Chemoforma Co., Basel, Switzerland), a commercial nucleotide product. The experimental diets were maintained isonitrogenous and isocaloric by adjusting amounts of casein, gelatin, and alanine. Five replicate groups of 12 juvenile red drum (10.2 ± 0.2 g/fish, mean ± SD) were fed each experimental diet for 4 wk, followed by an assay of neutrophil oxidative radical production and a bacterial challenge via intraperitoneal injection of Vibrio harveyi at 2.9 × 10⁷ colony-forming units/g fish. Fish fed all diets supplemented with various levels of purified nucleotides showed significantly ( P  < 0.01) enhanced weight gain and feed efficiency during the first week of feeding compared to fish fed the basal diet. However, the dietary effects became less significant during the following 3 wk of feeding. The transient growth-enhancing effect of dietary nucleotides observed in the present study may explain the conventional controversy about nucleotide effects on fish growth. Dietary supplementation with nucleotides had no influence on terminal whole-body composition.     

Comparative assessment of purine nucleotides adenosine,guanosine and inosine monophosphates as functional supplements on growth and health performances of red sea bream,Pagrus major juvenile

Purine nucleotides regulate the cellular functions in the animal body. The current study evaluates the comparative efficacy of dietary purine nucleotides, that is, adenosine monophosphate (AMP), guanosine monophosphate (GMP) and inosine monophosphate (IMP) in red sea bream Pagrus major. Semi‐purified basal diet was formulated (Control, D1) containing 550 g/kg protein, supplemented with purine nucleotides AMP, GMP and IMP at their optimum supplementation level (2, 4 and 4 g/kg) to formulate the experimental diet groups D2, D3 and D4, respectively. Initial weight of 3.5 ± 0.01 g fish was randomly fed test diets in triplicate. After 56 days, % weight gain (p = .003), specific growth rate (p = .003) and apparent lipid digestibility (p = .04) were significantly higher in fish fed diet group D4 followed by D3 and D2. Supplemented groups showed significantly higher feed intake in comparison to control (p = .001). Supplemented groups showed significantly increased and decreased NBT (p = .003) and CAT (p = .003) activity, respectively. Fish fed IMP supplemented diets had significantly lower blood urea nitrogen (p = .04), glutamyl oxaloacetic transaminase (p = .04) and glutamic‐pyruvate transaminase (p = .001) followed by other supplemented groups. Supplemented diet groups showed enhanced stress resistance. Interestingly, D2 and D4 groups showed best oxidative stress status of fish. Therefore, these results indicated that among purine nucleotides, supplementation of IMP could be a more effective nucleotide as functional supplement in red sea bream diet.