Encapsulation capacity of Artemia nauplii with customized probiotics for use in the cultivation of western king prawns (Penaeus latisulcatus Kishinouye, 1896)

The encapsulation capacity of Artemia nauplii with customized probiotics Pseudomonas synxantha and Pseudomonas aeruginosa for use in the cultivation of western king prawns (Penaeus latisulcatus) was investigated. Seven trials were conducted to investigate this encapsulation capacity in terms of Artemia survival and probiotic load in Artemia. Newly hatched Artemia nauplii at 250 nauplii mL^?1 were fed individual probiotics at 0, 10³, 10⁵ and 10⁷ colony‐forming units (CFU) per millilitre, and mixtures of these two probiotics (10⁵ CFU mL^?1) at 30:70, 50:50 or 70:30 v/v in a medium of ozonated water (OW), tryptone soya broth (TSB), and a mixture of these media. The appropriate medium for encapsulation of probiotics by Artemia nauplii was the mixture of OW and TSB at 75:25 v/v; whereas, the use of OW or TSB alone was not effective. Artemia nauplii most effectively encapsulated the customized probiotics at 10⁵ CFU mL^?1. The results indicates that the encapsulation of Artemia nauplii is optimized by using a combination of P. synxantha and P. aeruginosa at 50:50 v/v in a media mixture of OW and TSB at 75: 25 v/v. Artemia should be harvested at 48 h when survival is still high (78%) and the probiotic load in Artemia is high (3 × 10⁴ CFU nauplius^?1).     

Delivery of HUFA, probionts and biomedicine through bioencapsulated Artemia as a means to enhance the growth and survival and reduce the pathogenesity in shrimp Penaeus monodon postlarvae

One of the major problems in the shrimp culture industry is the difficulty in producing high-quality shrimp larvae. In larviculture, quality feeds containing a high content of highly unsaturated fatty acids (HUFA) and ingredients that stimulate stress and disease resistance are essential to produce healthy shrimp larvae. In the present study, Penaeus monodon postlarvae (PL15) were fed for 25 days on an unenriched Artemia diet (control; A) or on a diet of Artemia enriched with either HUFA-rich liver oil of the trash fish Odonus niger (B), probionts [Lactobacillus acidophilus (C1) or yeast-Saccharomyces cerevisiae (C2)] or biomedicinal herbal products (D) that have anti-stress, growth-promoting and anti-microbial characteristics. P. monodon postlarvae fed unenriched Artemia exhibited the lowest weight gain (227.9 ± 8.30 mg) and specific growth rate (9.95 ± 0.05%), while those fed the HUFA-enriched Artemia (B) exhibited the highest weight gain and specific growth rate (362.34 ± 12.56 mg and 11.77 ± 0.08%, respectively). At the end of the 25-day rearing experiment, the shrimp postlarvae (PL40) were subjected to a salinity stress study. At both low and high (0 and 50‰) salinities, the group fed the control diet (A) experienced the highest cumulative mortality indices (CMI) 935.7 ± 2.1 and 1270.7 ± 3.1, respectively. Those fed diet D showed the lowest stress-induced mortality, and CMI were reduced by 31.1 and 32.3% under conditions of low and high salinity stress, respectively. A 10-day disease challenge test was conducted with the P. monodon postlarvae (PL40–PL50) by inoculating the shrimp with the pathogen Vibrio harveyi at the rate of 10⁵–10⁷ CFU/ml in all rearing tanks. P. monodon postlarvae fed probiont-encapsulated Artemia diets (C1 and C2) exhibited the highest survival (94.3 and 82.3%, respectively) and lowest pathogen load (V. harveyi) in hepatopancreas (5.2 × 10² ± 9.0 × 10 and 4.6 × 10² ± 9.0 × 10 CFU g⁻¹, respectively) and muscle (2.0 × 10² ± 6 × 10 and 1.7 × 10² ± 8.6 × 10 CFU g⁻¹, respectively) tissues. The shrimp that were fed the unenriched Artemia (Control; A) showed the lowest survival (26.33%) and highest bacterial load in the hepatopancreas (1.0 × 10⁵ ± 5 × 10³ CFU g⁻¹) and muscle (3.6 × 10⁴ ± 6 × 10² CFU g⁻¹). The shrimp fed the herbal product (D)-enriched Artemia also exhibited enhanced survival and reduced V. harveyi load in the tissues tested compared to the control diet (A) group. The results are discussed in terms of developing a quality larval feed to produce healthy shrimp larvae.     

Effects of dietary Lactobicillus plantarum on the growth,carcass quality,and immune response of African catfish (Clarias gariepinus) challenged with Salmonella typhi

An experiment was conducted to investigate the effects of Lactobacillus plantarum on the production of African catfish (Clarias gariepinus). Five experimental diets containing 0, 10³, 10⁵, 10⁷, and 10⁹ CFU of Lactobacillus plantarum g^?1 diet (T₁–T₅ treatments respectively) were fed to African catfish (Clarias gariepinus) (9.20 ± 0.1 g initial body mass), for 70 days. Results indicated significantly lower growth performance in the fish fed diet without probiotics and in those fed diet with the least probiotic level. Treatments with probiotics significantly improved the blood profile and carcass protein but significantly reduced the carcass fat (P < 0.05); these treatments also marginally improved the carcass minerals in comparison with the treatment without probiotic (P < 0.05). Challenging the fish fed the experimental diets with Salmonella typhi showed higher immunity of fish fed the probiotic diets than those fed the nonprobiotic diet. Duncan’s multiple range test showed that the best fish performance was observed with 10³ CFU g^?1 L. plantarum for very parameter measured. However, regression analyses showed the optimum level of the bacteria to be 10^4.13–10⁵ CFU g^?1     

Dietary administration of Bacillus (B. licheniformis and B. subtilis) and isomaltooligosaccharide influences the intestinal microflora,immunological parameters and resistance against Vibrio alginolyticus in shrimp,Penaeus japonicus (Decapoda: Penaeidae)

The experiment was conducted to investigate the effects of oral administration of probiotics (Bacillus licheniformis and Bacillus subtilis) in combination with prebiotic isomaltooligosaccharide (IMO) on the intestinal microflora and immunological parameters of Penaeus japonicus and its resistence against Vibrio alginolyticus. A basal diet was supplemented with 0% probiotics and prebiotic (control), 10⁸ colony forming unit (CFU) g^?1B. licheniformis and 0.2% IMO (T1), 10⁸ CFU g^?1B. subtilis and 0.2% IMO (T2), 10⁸ CFU g^?1B. licheniformis in combination with 10⁸ CFU g^?1B. subtilis and 0.2% IMO (T3). The results showed that the total bacterial counts significantly increased (P<0.05) and Vibrio counts significantly decreased (P<0.05) in the intestine of shrimp with supplementation of dietary synbiotics. Shrimp fed the diet with both Bacillus probiotics and IMO (T3) produced significantly higher immune parameters (phenoloxidase activity, lysozyme activity and nitric oxide synthase activity and superoxide dismutase activity) than the control group (P<0.05). Significant lower cumulative mortality after challenge with V. alginolyticus was also observed in shrimp fed diet with both Bacillus probiotics and IMO (T3) than that in the control group (P<0.05). The results indicated that the oral administration of probiotics (B. licheniformis and B. subtilis) and prebiotic IMO has positive effects on bacterial flora in P. japonicus gut, and can activate non‐specific immunity of shrimp.     

Dietary Multispecies Probiotic Supplementation Enhances the Immunohematological Responses and Reduces Mortality by Aeromonas hydrophila in Labeo rohita Fingerlings

A study was conducted to determine the immunomodulatory effect of probiotic mixture on the nonspecific immune response and disease resistance of Labeo rohita. Fish were fed with six different test diets with or without probiotics, namely, T1 (basal feed [BF] without probiotics), T2 (BF + Bacillus subtilis [BS] + Lactococcus lactis [LL]), T3 (BF + LL + Saccharomyces cerevisiae [SC]), T4 (BF + BS + SC), T5 (BF + BS + LL + SC), and T6 (BF + heat‐killed bacteria of BS + LL + SC). During the prechallenge period, significantly higher (P < 0.01) nitroblue tetrazolium assay (NBT), red blood cells (RBC), hemoglobin (Hb), globulin, and albumin content were recorded in the probiotic‐supplemented diet group. Feeding all the three probiotics significantly decreased (P < 0.01) the serum aspartate aminotransferases (AST), alanine aminotransferases (ALT), acid phosphatase (ACP), and alkaline phosphatase (ALP) activity and increased the myeloperoxidase (MPO) and immunoglobulin M (IgM) value. Significant difference in the NBT, Hb, serum albumin, and MPO was noticed in both prechallenged and postchallenged fish. Lowest survivability was recorded in the nonprobiotic fed group, followed by the group fed with heat‐killed probiotics, whereas the highest survivability was noticed in the group fed with all the three probiotics in live form. Thus, a probiotic mixture diet constituting of three probiotics in viable form is found to be optimum to enhance the immunity and postinfection survivability in L. rohita fingerlings.     

Zingiber officinalis an herbal appetizer in the tiger shrimp Penaeus monodon (Fabricius) larviculture

Penaeus monodon postlarvae were fed with different percentages (0%, 25%, 50%, 75% and 100%) of the herbal appetizer Zingiber officinalis enriched Artemia. After 30 days of culture (i.e. PL‐1–30), a very positive result was found in Z. officinalis‐enriched Artemia‐fed postlarvae. The unenriched Artemia‐fed postlarvae consumed 91.0 mg/animal/30 days of feed, whereas the Z. officinalis‐enriched Artemia increased their consumption to 127.9 mg/animal/30 days. A similar pattern was noticed in feed absorbed (110.2 mg), dry weight growth (26.7 mg) and feed catabolized (83.2 mg) in Z. officinalis‐enriched Artemia because of enzymatic activities. The conversion efficiency of unenriched postlarva was 17.19%, whereas in 100%Z. officinalis‐enriched Artemia, the maximum conversion efficiency was 20.85%. The net production efficiency increased significantly (P < 0.05) to 22% from that of the unenriched Artemia‐fed postlarvae. The administration of Z. officinalis in all levels produced significantly (P < 0.05) higher weight gain and specific growth rate. The utilization efficiency of feed increased proportionately to the percentages of Z. officinalis. Digestive enzyme activity (amylase, protease and lipase) increased significantly (P < 0.05) in the 50%, 75% and 100% enrichment. Among the different percentages of enrichment, the 100%Z. officinalis‐enriched Artemia‐fed postlarvae performed better in the overall status.     

Evaluating the use of Lactobacillus acidophilus as a biocontrol agent against common pathogenic bacteria and the effects on the haematology parameters and histopathology in African catfish Clarias gariepinus juveniles

This study was carried out to evaluate the use of Lactobacillus acidophilus as a biocontrol agent against some common fish pathogenic bacteria (Staphylococcus xylosus, Aeromonas hydrophila gr.2 and Streptococcus agalactiae) in African catfish, Clarias gariepinus. Eight treatments were designed inclusive of 10 C. gariepinus juveniles (mean weight 190 g) per tank, each in triplicate. Four groups of fish were fed a diet supplemented with L. acidophilus, comprising about 3.01 × 10⁷ colony‐forming units per gram of diet (the probiotics diet), while the other four groups were fed a diet not supplemented with probiotics (the non‐probiotics diet). In the first group, fish were injected with 1 mL physiological saline and fed the non‐probiotic diet (non‐probiotic control); in the second, third and fourth groups, fish were injected with 1 mL each of S. xylosus, A. hydrophila gr.2 and S. agalactiae, respectively, and were all fed the non‐probiotic diet (designated as non‐probiotic treatments; NPsx, NPah and NPsa respectively). In the fifth group, fish were injected with 1 mL physiological saline but fed the probiotic diet (probiotic control), while fish in the sixth, seventh and eighth groups were each injected with 1 mL of S. xylosus, A. hydrophila gr.2 and S. agalactiae, respectively, and were all fed the probiotic diet (and designated as probiotic treatments; Psx, Pah and Psa respectively). Blood samples were collected for haematology analysis, while samples of the liver and kidney were examined for pathohistology after 7 and 21 days of infection. The results showed that the haematology parameters, packed cell volume, haemoglobin, erythrocyte sedimentation rate, red blood cell, white blood cell, total serum protein, Mg²⁺, Ca²⁺, Cl^?, glucose, cholesterol and total immunoglobulin concentrations and the pathohistology of the liver and kidney were better in the challenged fish (infected) maintained on the probiotic diet than those in the groups fed the non‐probiotic diet. It is concluded, based on these results, that L. acidophilus is useful as a probiotic agent in C. gariepinus against these pathogenic bacteria (S. xylosus, A. hydrophila gr.2 and S. agalactiae).     

Effect of probiotic on reproductive performance in female livebearing ornamental fish

A probiotic bacterial strain, Bacillus subtilis, isolated from the intestine of Cirrhinus mrigala (Hamilton), was incorporated in fish feed at four different concentrations (5 × 10⁸ cells g⁻², 5 × 10⁷ cells g⁻², 5 × 10⁶cells g⁻¹ and 5 × 10⁵ cells g⁻¹) and fed to four species of livebearing ornamental fish, Poecilia reticulata (Peters), Poecilia sphenops (Valenciennes), Xiphophorus helleri (Heckel) and Xiphophorus maculatus (Gunther) for one year duration to observe the effect of dietary probiotic supplementation on their reproductive performance. Sixty virgin females of each species were stocked separately in circular FRP tanks (350 L) and fed diets with varying levels of probiotic cells and control feed. Broodstock performance was evaluated based on gonadosomatic index (GSI), fecundity and fry production of female broodstock. The results showed that supplementation of feed with probiotics increased significantly (P<0.05) the GSI, fecundity and fry production of spawning females and length and weight of fry in all the four species of fish. The number of dead and deformed fry were also significantly lower (P<0.05) in fish fed with the probiotic feeds. The use of higher concentration of the probiont in diet did not always lead to significantly improved reproductive performance of the spawners. Collectively, this study showed that female livebearers benefit from inclusion of probiotics in diet during their reproductive stages.     

Effect of dietary supplementation with Bacillus subtilis on the growth,performance, immune response and antioxidant activities of the shrimp (Litopenaeus vannamei)

The objective of this study was to evaluate the effect of dietary supplementation of a probiotic bacterium, Bacillus subtilis, on the growth, immune response and antioxidant activities of shrimp (Litopenaeus vannamei). Shrimps with an average initial weight of 2.11±0.17 g were randomly assigned to four groups with three replicates. The control group was fed a basal diet, and three treated groups were fed diets supplemented with B. subtilis at doses of 1 × 10⁴, 5 × 10⁴ and 10 × 10⁴ colony‐forming unit (CFU) g^?1 feed respectively. After 40 days of culture, 10 shrimps from each replicate were taken randomly for the determination of immune response and oxidization resistance indices. The results showed that the shrimps fed with B. subtilis at a dose of 1 × 10⁴, 5 × 10⁴ CFU g^?1 feed showed significantly better growth than that of the control diet. The phenoloxidase activities showed a tendency to increase with an increased dose of B. subtilis in diets but there was no significant difference among the three treated groups. In addition, phenoloxidase activities were found to be significantly higher (P<0.05) in the groups treated with B. subtilis than that of the control group. Shrimps treated with 5 × 10⁴ CFU g^?1 feed probiotic bacterium showed the highest lysozyme activity and it was significantly higher (P<0.05) than the other groups. However, there was no significant difference in acid phosphatase and alkaline phosphatase activity across all the groups. The total antioxidant capacity, superoxide dismutase and glutathione peroxidase activities in the probiotic‐treated groups were significantly increased (P<0.05) as compared with the control groups. Both maleic dialdehyde concentration and superoxide anion activities in the probiotic‐treated groups were significantly lower (P<0.05) than those of the control. The probiotic did not affect the nitric oxide synthase and the catalase activity in any of the control and treated groups. These results indicated that the probiotic B. subtilis could significantly promote the growth rate of shrimp by increasing the immune function and antioxidant capacity. The most effective dose of B. subtilis in the diet was 5 × 10⁴ CFU g^?1 feed.     

Enrichment of Artemia nauplii with the probiotic yeast Saccharomyces boulardii and its resistance against a pathogenic Vibrio

Enrichment of Artemia nauplii with a known probiotic yeast Saccharomyces boulardii (SB) and its role in enhancing resistance against the pathogen Vibrio harveyi was investigated. SB was cultured, then fed to instar II Artemia nauplii in three different treatments; 10² (T1), 10³ (T2) and 10⁴ (T3) colony forming units (CFU) per ml in triplicate. The algae Nanochloropsis sp. was used as control diet. Survival and total count of CFU nauplii⁻¹ was observed on different media (Sabouraud, for enumerating yeasts, thiosulphate citrate bile salts sucrose, for enumerating Vibrio and seawater agar, for enumerating total aerobic flora) for each replication. Enhanced survival of nauplii was observed in treatments as compared to control. Results indicated that enrichment of SB in Artemia nauplii proceeded in a linear fashion, and up to 3500 CFU of SB could be detected in one nauplii at 10⁴ CFU ml⁻¹ treatment. No conclusive trend could be observed in the count of Vibrio and total aerobic flora due to treatment. Enriched nauplii were then challenged with the pathogen V. harveyi for 24 and 48 h at a concentration of 6.1 × 10⁶ CFU ml⁻¹. The survival counts at 48 h showed that the resistance of the nauplii was significantly (P < 0.01) improved in those fed with 10⁴ CFU  ml⁻¹ SB (90% survival rate after 48 h of challenge versus less than 40% for the infected control group without SB and treatments T1 and T2). This study shows that SB, which has been used for the first time in an aquatic live feed organism, has a profound beneficial effect on the nauplii by increasing its resistance to a pathogenic Vibrio infection. This revised version was published online in August 2006 with corrections to the Cover Date.     

Changes in the growth performance,antioxidant enzymes and stress resistance caused by dietary administration of synbiotic (fructooligosaccharide and probiotics) in juvenile Chinese Mitten Crab,Eriocheir sinensis

The research aimed to evaluate the effects of dietary fructooligosaccharide, probiotics and their combination on the growth performance, antioxidant enzymes and stress resistance of juvenile Eriocheir sinensis. Crabs (average weight: 9.90?±?0.07 g) were randomly assigned into 4 groups (3 tanks per group) fed experimental diets: basal diet (control group), basal diet supplemented with 5 g/kg FOS, basal diet supplemented with 2 g/kg multi-strain probiotics (each gram contains Lactobacillus acidophilus 10⁶ CFU?+?Bacillus subtilis 10⁷ CFU?+?Saccharomyces cerevisiae 10¹⁰ CFU) and basal diet supplemented with symbiotic (5 g/kg FOS?+?2 g/kg multi-strain probiotics) (designated as control, D1, D2 and D3, respectively). After 8 weeks of feeding trial, crabs were exposed to the transportation process (3 h). Cumulative mortality was recorded at 24 h, 48 h, 72 h and 96 h after transport stress, and pre-transport and post-transport sampling of hepatopancreas occurred for assay. The results indicated that crabs fed D3 had significantly higher weight gain (WG), specific growth rate (SGR) and lower feed conversion ratio (FCR) than crabs fed control diet. Before stress, compared to the control group, crabs fed D1 and D3 diet significantly increased catalase (CAT), superoxide dismutase (SOD) activities and decreased malondialdehyde (MDA) activities, the highest activities of pepsin, trypsin and chymotrypsin were observed in crabs fed D2 diet. After stress, there was a trend that the activities of antioxidants enzymes and proteases in all groups were significantly decreased. And compared to the control group, crabs fed D1 and D3 diet significantly improved SOD and CAT activities, the lowest MDA activity was observed in crabs fed D3 diet, no significant difference was obtained in activities of total antioxidant capacity (T-AOC) and three proteases among all groups (P?>?0.05). At 96 h after transportation process, the lowest cumulative mortality was observed in crabs fed D3 diet, the difference among all groups before and at 24 h, 48 h and 72 h after stress was not significant (P?>?0.05). In summary, a basal diet supplemented with synbiotic could improve the growth performance and protect the hepatopancreas of Eriocheir sinensis more effectively than singular supplementation with prebiotics or probiotics.

     

Bioencapsulated probiotics increased survival, growth and improved gut flora of turbot (Psetta maxima) larvae

Bacterial diseases are probably the major cause of mortality in aquaculture. The use of probiotics is one of the solutions to manage bacterial infections, by preventing the colonization and exclusion of pathogenic bacteria. The effect of two selected probiotics in turbot (Psetta maxima) larvae was evaluated. Turbot larvae were reared on three different dietary treatments consisting of newly hatched Artemia nauplii from day 16 to 34 post-hatch. Groups A and B were fed with Artemia-containing probiotics FAA and FAB, respectively, and group C was control group. Results indicated that the addition of probiotics increased survival and promoted turbot growth, showing that they were beneficial for the aquaculture of turbot. Moreover, turbot fed with bioencapsulated probiotics attained higher percentages of survival during its development.     

Haematologic and immunologic parameters of bullfrogs,Lithobates catesbeianus,fed probiotics

The effects of two probiotics (P₁–Lactobacillus acidophilus, Bifidobacterium bifidum and Enterococcus faecium and P₂–Bacillus subtilis) supplemented to commercial feed (40% crude protein) on the haematological and immunological parameters of the bullfrog Lithobates catesbeianus were studied. Two doses of each probiotic (5 and 10 g kg^?1 of food) were added to the diets and fed to frogs, totalling five treatments over 112 days. Haematological analyses consisted of total and differential leucocyte counts, erythrocyte and thrombocyte counts, haematocrit, haemoglobin levels and RBC indices (mean corpuscular volume, mean corpuscular haemoglobin – and mean corpuscular haemoglobin concentration) and the immunological parameters included phagocytic capacity and phagocytic index of peritoneal phagocytes. The results showed that the probiotics did not significantly influence any of the haematological parameters measured. However, immunological assays showed that the probiotics had an immunostimulating effect. The greatest effects were seen with probiotic P₁ fed at a dose of 10 g kg^?1 of diet and probiotic P₂ fed at 5 g kg^?1 of diet.     

Effects of probiotic Pediococcus acidilactici on growth performance,survival rate,and stress resistance of Persian sturgeon (Acipenser persicus)

This study was conducted to examine the effect of Artemia urmiana nauplii enriched with Pediococcus acidilactici on growth performances, survival rate, and stress resistance of Persian sturgeon (Acipenser persicus). Artemia nauplii were enriched with P. acidilactici at concentration of 10¹⁰ CFU/ml for 3 h (T3), 6 h (T6), 9 h (T9), and one nonenriched nauplii treatment (control). Since nauplii enriched for 9 h had the most significant CFU/g, fish were fed with T9 for 11 days and compared with the control. To evaluate the effect of probiotic on fish resistance, Persian sturgeon larvae were subjected to osmotic shocks of 15, 25, or 35 ppt; four pH treatments, pH 5, pH 6, pH 8 or pH = 9; and air for 5, 10, 15, or 20 s on the 11th day. There were no significant differences in final weight, weight gain, CF, SGR, and FCR between T9 and control (P > 0.05). However, the survival rate of larvae fed nauplii enriched for 9 h increased significantly in comparison with the control group (P < 0.05). In addition, significant higher resistance to all stress challenges was observed in the T9 group.     

To what extent can maternal inherited immunity acquired from a crustacean‐enhanced diet improve the performance and vitality of the offspring and enhance profitability of European Sea bass (Dicentrarchus labrax)?

This study was conducted to investigate the effects of maternal inherited immunity acquired from crustacean‐enhanced diets on the vitality and profitability of sea bass offspring. Newly hatched larvae produced from three groups of broodstock were evaluated. The broodstock were fed (a) a basal diet (BD), (b) a Palaemon‐supplemented diet (PSD), and (c) an Artemia‐supplemented diet (ASD) for 42 days. A total of 400,000 larvae at 3 days posthatch (DPH) produced from each treatment were stocked in larval rearing tanks at 40 larvae/L for 42 days. Survival (%) was improved by 37 and 9.96% in the groups fed ASD and PSD compared with the control group. The growth, swim bladder (%), and condition factor all significantly (p ≤ 0.05) improved in the postlarvae produced from broodstock enhanced with crustacean diets. Compared with the BD group, the serum lysozyme activities of the fish groups fed ASD and PSD increased by 45.6 and 11.7%, respectively. Sea bass fry (90DPH) produced from broodstock fed ASD showed the best tolerance to salinity/temperature stress tests. Furthermore, the profitability improved in ASD and PSD compared with the BD group. In conclusion, sea bass broodstock enhanced with Artemia biomass produced offspring of superior quality with less cost and greater profit margins.     

Effect of dietary supplementation of inulin and W. cibaria on haemato‐immunological parameters of hybrid surubim (Pseudoplatystoma sp)

The dietary supplementation of prebiotics, probiotics and symbiotic in hybrid surubins (a Pseudoplatystoma corruscans and P. fasciatum cross) was evaluated for the effects on their autochthonous intestinal microbiota and on haematological and immunological parameters. A total of 160 fish were divided into four treatment groups with four replicates each. The treatment groups were fed with the following diets for 15 days: control diet without supplementation; 0.5% inulin (prebiotic) supplementation; Weissella cibaria (CPQBA 001‐10 DRM 02) (7.87 ± 0.2 log CFU g^?1) supplementation; or 0.5% inulin and W. cibaria supplementation (symbiotic group). The midgut intestines of the fish with the symbiotic diet supplementation had higher concentrations of lactic acid bacteria (7.07 ± 1.11 log CFU g^?1) and low levels of Vibrio spp (1.90 ± 0.60 log CFU g^?1) and Pseudomonas spp (2.23 ± 1.48 log CFU g^?1). In addition, increased erythrocytes and reduced circulating neutrophils were observed in this group. No differences in blood glucose, serum protein or lysozyme levels were detected between treatment groups. However, a higher concentration of total immunoglobulin was observed in fish fed with the probiotic and symbiotic diets. The addition of 0.5% inulin (prebiotic) thus W. cibaria (probiotic) to the diet of Pseudoplatystoma hybrid surubins reduce the number of pathogenic bacteria and stimulate the beneficial intestinal microbiota and may possibly alter their immune defence system.     

Effects of Bacillus subtilis Strains on Growth,Immune Parameters,and Streptococcus iniae Susceptibility in Nile Tilapia,Oreochromis niloticus

This study was conducted to evaluate the effects of probiotic‐amended diets fed to juvenile Nile tilapia, Oreochromis niloticus, on growth and susceptibility to Streptococcus iniae infection. Fish (average weight 16.5 ± 0.2 g) were fed five diets formulated with Bacillus subtilis strains SB3086, SB3295, SB3615, or AP193 either individually or in combination of strains SB3086 and SB3615 at a targeted concentration of approximately 4 × 10⁷ colony‐forming units (CFU)/g of feed or with a basal control diet with no additives for 21 d. After the 21‐d growth trial, no significant difference in growth performance was observed with any probiotic‐amended diet. Results from serum bactericidal activity showed a significant difference between treatments and the control (P = 0.0002), except for the SB3295‐amended diet (P = 0.9020). Lysozyme activity was also significantly different in fish fed probiotic diets from those fed control diet (P = 0.0001). After 21 d of feeding, fish were challenged with S. iniae by intraperitoneal injection at a dosage of 8 × 10⁶ CFU per fish. Results from the challenge also showed a significant difference between treatments and control (P = 0.0001). Overall, fish fed with strain SB3615 showed the lowest percent mortality (44.0 ± 7.2%) and those fed the control diet showed the highest mortality (77.3 ± 7.0%). The combined feeding with strains SB3086 and SB3615 did not result in any significant difference in reducing mortality because of S. iniae infection in juvenile Nile tilapia when compared with the individual probiotic treatments.     

Assessment of the effects of vegetative and lyophilized Pediococcus acidilactici on growth,feed utilization,intestinal colonization and health parameters of rainbow trout (Oncorhynchus mykiss Walbaum)

A study was conducted to assess the probiotic effect of different dietary forms of Pediococcus acidilactici on rainbow trout (Oncorhynchus mykiss Walbaum). Growth performance, feed utilization, intestinal colonization and basic health status were investigated after a 10 week feeding trial. Fish were fed either vegetative (Veg) or lyophilized (Lyo) cells incorporated into a basal diet at either 10⁷ (Lo) or 10⁸ (Hi) CFU g^?1. P. acidilactici temporarily colonized the digestive tract (as both epithelium associated and transient populations) in all probiotic groups during supplemented feeding. Scanning electron microscopy confirmed the presence of localized colonization of P. acidilactici‐like cells between intestinal folds of the probiotic fed fish. Compared to the control group, no significant improvements in growth performance, feed utilization or carcass composition were observed in the probiotic fed fish (P > 0.05). However, a significant reduction of condition factor (K) was evident in fish fed the lyophilized diets. Increased leucocyte levels were observed in fish fed the low level vegetative P. acidilactici supplemented diet yet leucocyte types were not affected. The study demonstrates some potential for the application of P. acidilactici with rainbow trout but further research is required to optimize applications.     

Improvement of reproductive indices,lysozyme activity,and disease resistance in live‐bearing ornamental fish,Poecilia latipinna using Artemia supplementation with treated yeast cell,Saccharomyces cerevisiae

In the present study, the effects of Artemia supplemented with 2‐β‐mercapto‐ethanol (β‐ME) treated yeast cell, Saccharomyces cerevisiae, on growth and reproductive performance, lysozyme activity, and disease resistance to Aeromonas hydrophila of freshwater ornamental species, Poecilia latipinna, were investigated. Within 60 days, molly fish were fed with three treatments including commercial food (T1), un‐supplemented Artemia (T2), and Artemia supplemented with β‐ME‐treated yeast cell (at concentration of 4 × 10⁷ CFU/L of water) (T3). After the feeding period, the fish were exposed to 100 μl of a suspension (1.1 × 10⁷ cells/ml) of A. hydrophila (BCCM5/LMG3279) and the cumulative mortality rates were recorded for 12 days. No significant difference was found between survival rate and growth performance of P. latipinna except for weight gain that was higher in fish fed through Artemia supplemented with β‐ME‐treated yeast cell compared to control group. Fecundity rate was significantly improved in fish fed using T3 with the maximum amount of 49.5 ± 2.29 per female (p < 0.05). Besides, lysozyme activity was significantly increased in group 3 (p < 0.05). Moreover, lowest fish mortality was significantly observed in this treatment (p < 0.05). In addition, the number of colonies formed by yeast cell in T3 (634 × 10³ CFU/g intestine) showed significant difference with other treatments (p < 0.05). In sum, Artemia enriched with β‐ME‐treated yeast improved reproductive indices, immune responses, and resistance against A. hydrophila of P. latipinna.     

Effect of dietary administration of Psychrobacter sp. on the growth,feed utilization,digestive enzymes and immune responses of grouper Epinephelus coioides

A 60‐day feeding trial was conducted to assess the effect of incorporating dietary Psychrobacter sp., one predominant bacterium with antagonistic activity in the gut of fast‐growing grouper Epinephelus coioides, on the growth, feed utilization, digestive enzymes and immune responses of E. coioides at regular monthly intervals. The fish were fed with control diet (without probiont) or probiotic diet supplemented with 1.0 × 10⁸ CFU g^?1Psychrobacter sp. No significant improvement in weight gain (WG) and specific growth ratio (SGR) were observed in the probiotic group, but a significant improvement in feed conversion ratio (FCR) was observed in fish fed the probiotic diet for 60 days. Although not statistically significant, enhanced hepatopancreatic protease and lipase activities and intestinal amylase activity were observed in probiotic group at day 60. A slightly increase in phagocytic activity and phagocytic index was observed in fish fed probiotic diet for 60 days. Serum lysozyme activity showed no significant differences between the probiotic group and the control group during the whole experiment period, while an increasing trend of superoxide dismutase (SOD) activity in the probiotic group was observed. Serum complement component 3 (C3) level of the probiotic group was higher than that of control in the whole feeding period, while complement component 4 (C4) level of the probiotic group was significantly higher than that of the control at day 60. The results of the current study firstly demonstrated potential for Psychrobacter sp. as a novel probiont to improve feed utilization, digestive enzymes and innate immunity in E. coioides.