Evaluation of commercial live bakers’ yeast, Saccharomyces cerevisiae as a growth and immunity promoter for Fry Nile tilapia, Oreochromis niloticus (L.) challenged in situ with Aeromonas hydrophila

This study was carried out to evaluate the use of commercial live bakers’ yeast, Saccharomyces cerevisiae as a growth and immunity promoter for Nile tilapia, Oreochromis niloticus (L.). Fish (0.33 g) were randomly distributed at 25 fish per 140-L aquarium and fed a diet containing 0.0, 0.25, 0.50, 1.0, 2.0, or 5.0 g yeast/kg diet for 12 weeks. After the 12-week experimental period, fish of each treatment were challenged by pathogenic Aeromonas hydrophila, which was given by interperitoneal (IP) injection and kept under observation for 10 days to record clinical signs and the daily mortality rate. The growth-promoting influences of bakers’ yeast were observed with fish and the optimum growth, feed utilization, and protein turn-over were obtained with 1.0–5.0 g yeast/kg diet. Also, yeast supplementation increased protein deposition in fish body. Biochemical parameters were improved in fish fed yeast up to 1.0 g/kg diet. Total fish mortality 10-days after IP injection with A. hydrophila and its count after incubation with fish serum decreased with the increase of yeast level in fish diets. However, the lowest fish mortality and bacterial counts were obtained in fish fed 5.0 g yeast/kg. These results indicate that bakers’ yeast supplement is promising as an alternative method to antibiotics for disease prevention in tilapia aquaculture, and the optimum level of live bakers’ yeast is about 1.0 g per kg diet.     

The Use of American Ginseng (Panax quinquefolium) in Practical Diets for Nile Tilapia (Oreochromis niloticus): Growth Performance and Challenge with Aeromonas hydrophila

This study was carried out to evaluate the effect of American ginseng (AG), Panax quinquefolium, on growth and resistance to Aeromonas hydrophila in Nile tilapia, Oreochromis niloticus. Ginseng was included in practical test diets at rates of 0.0 (control), 0.50, 1.0, 2.0, or 5.0 g/kg diet. Fish (9.1 ± 0.3 g) were distributed into quadricated 100-L aquaria at a density of 20 fish per aquarium. Fish in all treatments were fed up to satiation twice daily for 8 weeks. After the feeding trial, fish of each treatment were intraperitoneally injected with pathogenic A. hydrophila and kept under observation for 10 days. Highest growth was obtained at 1.0 – 5.0 g AG/kg diet. The survival of fish challenged by A. hydrophila increased with increasing AG levels in fish diets. Cost-benefit analysis indicated that ginseng supplementation could reduce per kg costs by 15% with an optimum inclusion level of 2.0 g/kg.     

Interactive effects of dietary protein and live bakery yeast, Saccharomyces cerevisiae on growth performance of Nile tilapia, Oreochromis niloticus (L.) fry and their challenge against Aeromonas hydrophila infection

Yeasts used as a probiotic in fish diets could stimulate fish resistance against bacterial infection and could enhance the activities of digestive enzymes in fish guts. In addition to yeast importance, dietary protein is another important part in fish diets that should be carefully optimized to meet fish requirement. It is proposed that the yeast supplementation may enhance the dietary protein turnover and reduce the protein requirement for fish. Therefore, the interactive effects of dietary protein and yeast levels on the growth performance of Nile tilapia, Oreochromis niloticus (L.) fry and their challenge against Aeromonas hydrophila infection was evaluated. In the present study, ten experimental diets were formulated to contain either 35% or 45% crude protein (CP). For each protein level treatment, bakery yeast (Saccharomyces cerevisiae) was supplemented at 0.0, 0.50, 1.0, 2.0, or 5.0 g/kg diet. Fish (0.25–0.48 g) were distributed at a rate of 25 fish per 140-L aquarium. For each diet, triplicate aquaria were fed twice a day, 5 days a week for 12 weeks. Fish growth and feed utilization were significantly affected by either dietary protein or yeast levels alone, while no significant effect of their interaction was observed. The highest fish growth was obtained at 1.0–5.0 g yeast/kg diet at both protein levels; however, the fish performance at 45% CP was better than that fed on 35% CP diets. The optimum feed conversion ratio (FCR) was obtained when fish fed on 1.0–5.0 and 2.0–5.0 g yeast/kg diet at 35 and 45% CP, respectively. The cumulative fish mortality, after interperitoneal injection with A. hydrophila for 10 days, and bactericidal activity was significantly higher in fish fed 35% CP diets than those fed 45% CP diets. Both variables decreased significantly with the increase in yeast levels. The lowest bacterial count and bactericidal activity were obtained in fish fed 5.0 g yeast/kg diet irrespective to dietary protein levels. It could be concluded that the inclusion of live bakery yeast in practical diets could improve the growth performances, feed utilization, and physiological status of Nile tilapia fry and their challenge against A. hydrophila infection. Moreover, fish performance when fed 45% CP diet was better than those fed 35% CP diet. Based on these results, the most suitable yeast level for maximum Nile tilapia growth was determined to be 2.0 g yeast/kg diet with 45% CP diet; however, this level was recommended to stimulate their productive performance and enhances their resistance against A. hydrophila infection.     

Stimulatory effect of dietary clove,Eugenia caryophyllata,bud extract on growth performance,nutrient utilization,antioxidant capacity,and tolerance of African catfish,Clarias gariepinus (B.), to Aeromonas hydrophila infection

The occurrence of pathogenic bacteria, Aeromonas hydrophila, in farm‐raised fish requires urgent attention. Continuous and indiscriminate use of antibiotics as growth promoters and disease control agents in aquaculture have been discouraged because of the risk of development of antibiotic‐resistant bacterial strains. There is steady interest in the use of botanicals, such as clove, Eugenia caryophyllata, buds extract (ECBE), as alternatives. Hence, the present study evaluated the effect of dietary ECBE supplementation on the growth performance, physiological, antioxidant, and immunity biomarkers of African catfish, Clarias gariepinus. Fish (11.7 ± 0.5 g) were fed diets containing 0.0 (control), 5.0, 10.0, or 15.0 g ECBE/kg diet up to apparent satiation twice daily for 12 weeks. After the feeding trial, fish from each treatment were challenged with A. hydrophila infection by intraperitoneal injection and kept under observation for 14 days to record any abnormal clinical signs and daily mortality. The results demonstrated that fish performance and feed intake were significantly enhanced with increasing ECBE levels, and its optimum level is 15 g/kg diet. Further, the dietary ECBE increased significantly the intestinal villi length/width and absorption area in a dose‐dependent manner. There are significant progressive increases in the values of red blood cells, hemoglobin, hematocrit, white blood cells, platelets, lymphocytes, and heterocytes, while monocytes, eosinophil, and basophils decreased significantly due to dietary ECBE in a dose‐dependent manner. Highest glucose, cholesterol, total protein, globulin, and albumin‐globulin ratios, aspartate aminotransferase (AST), alanine aminotransferase (ALT), alkaline phosphatase (ALP), urea, and creatinine values were found in fish fed 15 g ECBE/kg diets, while lowest values were recorded in fish fed the control diet. Despite the high AST and ALT values, no visible lesions or damage were observed in the liver cells of fish fed ECBE‐enriched diets. In addition, the inclusion of ECBE in fish diets enhanced the antioxidant and immunity capacity. Fish mortality after the bacterial challenge was higher in fish fed the control diet (82.3%) than those fed ECBE‐enriched diets. The lowest fish mortality was observed in fish fed the 15 ECBE/kg diet (4.7%) [Correction added on 16 November 2018: this section has been revised for clarity.].     

Live Spirulina (Arthrospira platensis) as a growth and immunity promoter for Nile tilapia, Oreochromis niloticus (L.), challenged with pathogenic Aeromonas hydrophila

The use of antibiotics to control fish disease is one of the constraints in tilapia farming. Hence, the use of probiotic and live organisms as alternative strategies has received much more attention. This study was undertaken to evaluate the use of Spirulina (Arthrospir platensis) as a growth and immunity promoter for Nile tilapia, Oreochromis niloticus (L.). Fish (1.88 g) were randomly distributed at 20 fish per 100 L aquarium and fed a diet containing either 0.0, 1.25, 2.5, 5.0, 7.5 or 10.0 g Spirulina kg^?1 diet for 12 weeks. After the feeding trial, fish of each treatment were challenged by pathogenic Aeromonas hydrophila, which was given by an interperitoneal injection, and they were kept under observation for 10 days to record any abnormal clinical signs and the daily mortality rate. The growth‐promoting influence of Spirulina was observed with fish, and the optimum growth and feed utilization were obtained at 5.0 g Spirulina kg^?1 diet. No significant changes were observed in fish survival among the different treatments. Spirulina supplementation improved the protein and lipid contents in fish bodies without significant differences among them, especially when fed 2.5–10.0 g kg^?1 diet, but no significant differences in the moisture and ash contents were observed among different treatments. The physiological parameters were improved when fish were fed a Spirulina‐enriched diet. However, the highest red blood cells, white blood cells and nitro blue tetrazolium values were obtained at 5.0–10.0 g Spirulina kg^?1 diet; meanwhile, the lowest value was obtained in the control. Total fish mortality due to A. hydrophila infection decreased with an increase in the Spirulina level in fish diets. These results indicate that Spirulina supplement is promising as an alternative method to antibiotics for disease prevention in tilapia aquaculture, and the optimum level of Spirulina in the fish diet should be 5.0–10.0 g kg^?1 diet.     

Effect of Coriolus versicolor polysaccharides on the hematological and biochemical parameters and protection against Aeromonas hydrophila in allogynogenetic crucian carp (Carassius auratus gibelio)

The effect of dietary intake of Coriolus versicolor Polysaccharides (CVP) on the hematological and biochemical indices of Allogynogenetic crucian carp (Carassius auratus gibelio) was investigated. Fish were fed CVP supplemented diets (0, 0.25, 0.5, 1.0, 2.0 or 4.0 g CVP kg^?1) for 56 days. The RBC, WBC counts, hemoglobin content, ESR in blood and TP, ALT, AST, ALP, GLU, CHO, TG, and BUN in serum were measured on day 0, 14, 28, 42, and 56. After feeding of 56 days, fish were infected with Aeromonas hydrophila and mortalities were recorded. The results indicated that feeding crucian carp with suitable dose of CVP enhanced the RBC, WBC counts, hemoglobin and TP content, ALP activity, and decreased the ESR, ALT, AST, GLU, CHO, TG and BUN. There was no effect in fish at low dose (0.25 g kg^?1). Unexpectedly, the higher CVP dose used here (2.0 and 4.0 g kg^?1) has a negative effect in fish. The results of challenge experiment indicated that a moderate level of CVP in the diet (1.0 g kg^?1) was the most effective to enhance the survival of fish after infected with A. hydrophila. In summary, the use of CVP, as dietary supplements, can improve the innate defense of crucian carp providing resistance to pathogens.     

Effects of Bacillus coagulans on Growth Performance,Disease Resistance,and HSP70 Gene Expression in Juvenile Gibel Carp,Carassius auratus gibelio

We studied the effects of Bacillus coagulans on growth, nonspecific immune parameters, and disease resistance in juvenile gibel carp. The fish were randomly divided into five groups: a control group fed a basic diet and four treated groups fed the basic diet supplemented with 125, 250, 500, and 1000 mg/kg B. coagulans, respectively, for 8 wk. Growth; plasma lysozyme activity; respiratory burst activity of phagocytes (RBAP); and the activity of tumor necrosis factor‐α (TNF‐α), interleukin‐1β (IL‐1β), and antioxidant enzymes were determined. The group that received 250 mg/kg B. coagulans showed an improved protein efficiency ratio, plasma lysozyme activity, superoxide dismutase, and superoxide anion radical scavenging activity and heat shock protein (HSP70) gene expression compared with the control group. Moreover, the 250 mg/kg B. coagulans group had a reduced feeding rate, feed conversion ratio, and plasma malondialdehyde content compared with the control group. The weight gain rate, protein efficiency ratio, plasma lysozyme, RBAP, TNF‐α, and superoxide anion radical scavenging activity and HSP70 gene expression were significantly increased, whereas the feed conversion ratio was significantly reduced, in the group supplemented with 500 mg/kg B. coagulans compared with the control. Artificial infection with Aeromonas hydrophila revealed a cumulative mortality in the control group that was higher than that in the 250, 500, and 1000 mg/kg B. coagulans groups. The results suggest that feed supplementation with 250–500 mg/kg B. coagulans has the potential to stimulate immunity, increase resistance against pathogenic infection, and promote growth in gibel carp.     

Effects of dietary supplementation with probiotic live yeast Debaryomyces hansenii on the immune and antioxidant systems of leopard grouper Mycteroperca rosacea infected with Aeromonas hydrophila

Two trials were conducted to determine the efficacy of fish fed live yeast Debaryomyces hansenii strain CBS 8339 on immune and antioxidant systems in leopard grouper Mycteroperca rosacea infected with Aeromonas hydrophila. Juveniles (12±0.5 g) were fed with a control diet or a D. hansenii‐supplemented diet (10⁶ colony‐forming units per gram) for 5 weeks. The live weight of fish was registered on a weekly basis. After 4 weeks, fish from each treatment were immunocompromised with pathogenic A. hydrophila and further fed for 1 week in order to evaluate the effect on immunological and antioxidant parameters. Generally, the results showed enhanced growth performance in fish fed the diet containing yeast compared with the control. Addition of live yeast had no significant effect on the immunological parameters after 4 weeks of feeding. However, post infection with A. hydrophila fish fed the yeast‐supplemented diet resulted in a significant increase in the levels of plasmatic immunoglobulin M. Superoxide dismutase and catalase (CAT) activities were significantly higher in the yeast group. In this fish, CAT and heat shock protein 70 genes were up‐regulated before and after infection of A. hydrophila. The present study is the first one reporting that yeast (D. hansenii) can enhance immunity and resistance against A. hydrophila.     

Effects of dietary probiotic Lactobacillus plantarum and whey protein concentrate on the productive parameters,immunity response and susceptibility of Nile tilapia,Oreochromis niloticus (L.), to Aeromonas sobria infection

Immunostimulatory feed supplements have an increasingly interest in aquaculture management. Generally, an individual supplement was used in fish diets but it is expected that the use of multi‐supplements may show synergistic enhancements in fish performance, health, and immunity. Therefore, the present investigation was carried out to evaluate the use of dietary probiotic Lactobacillus plantarum and whey protein concentrate (WPC) in practical diets for Nile tilapia, Oreochromis niloticus. Hence, probiotic L. plantarum, WPC and their mixture were incorporated into a basal fish diet (300 g/kg crude protein) as follows: T1 = a basal control diet, T2 = a basal diet containing L. plantarum, T3 = a basal diet containing 1.0 g WCP/kg diet and T4, T5 or T6 = basal diets containing probiotic L. plantarum + 1.0, 2.0 or 3.0 g WCP/kg diet, respectively. Fish (15.2 ± 0.6 g) were fed on one of the tested diets up to apparent satiation twice a day for 60 days. After that, fish were intraperitoneally injected with pathogenic bacteria Aeromonas sobria and fish mortality was observed for 10 days postchallenge. Fish growth and feed intake were significantly improved by dietary probiotic L. plantarum (T2) and/or WPC (T3) over the control group (T1), and highest fish performance was observed in T5–T6 fish groups. Similarly, highest values of haematocrit, glucose, total proteins, albumin, and globulin were significantly observed in T5–T6 fish groups. Likewise, fish fed dietary probiotic L. plantarum (T2), WPC (T3), and their mixture (T4–T6) showed antioxidants and immune‐stimulating activities better than the control group. Fish fed the control diet were more susceptible to A. sobria infection showing highest fish mortality (75.0%). Meanwhile, dietary probiotic L. plantarum (T2), WPC (T3), and their mixture (T4–T6) enhanced significantly the fish resistance to A. sobria infection resulting in maximum values of relative percent of fish survival (73.3%–80.0%) in T5–T6 groups. The present investigation recommended the use of probiotic L. plantarum with 2.0 g WPC/kg diet to improve the growth, antioxidant, immunity responses and tolerance of Nile tilapia to A. sobria infection.     

Evaluation of levamisole as a feed additive for growth and health management of hybrid striped bass (Morone chrysops × Morone saxatilis)

Three separate experiments were conducted with juvenile hybrid striped bass to determine the effects of levamisole as a feed supplement on growth performance, innate immunity and specific antibody responses, as well as resistance to Streptococcus iniae and Aeromonas hydrophila infection. A basal diet was formulated to contain 40% protein, 10% lipid and an estimated digestible energy level of 3.5 kcal/g. Four levels (100, 250, 500 and 1000 mg/kg) of levamisole were added to the basal diet in place of cellulose. After the 3-week feeding period in feeding trial 1, enhanced weight gain was generally observed in fish fed the diets supplemented with a low level (< 500 mg/kg) of levamisole. Dietary supplementation of levamisole at 100 mg/kg significantly (P < 0.05) enhanced growth and feed efficiency, compared to fish fed the basal diet. Fish fed diet supplemented with 1000 mg levamisole/kg diet showed chronic toxicity signs of inferior growth, reduced feed intake and feed efficiency. Although the extracellular superoxide anion production of head kidney cells, hematocrit, serum lysozyme and peroxidase were not significantly affected by dietary treatments, intracellular superoxide anion production of head kidney macrophages of fish fed 250 mg levamisole/kg diet was significantly (P < 0.05) higher than that of fish fed the other four diets. The hypothesized benefits of dietary supplementation of levamisole in reducing mortality from infection of pathogenic bacteria including S. iniae and A. hydrophila were not proven after two separate 3-week feeding trials and disease challenges in the present study. Agglutinating antibody titers of individual fish were highly varied and not significantly influenced by dietary levamisole at the tested levels.     

Effect of dietary willow herb,Epilobium hirsutum extract on growth performance,body composition,haematological parameters and Aeromonas hydrophila challenge on common carp,Cyprinus carpio

The present study was conducted to evaluate the use of Epilobium hirsutum extract in diet of common carp, Cyprinus carpio (20 ± 2 g). Different levels of plant extract (0%, 0.5%, 1, 3% and 3%+2‰ multivitamin (2 g of multivitamin per kg diet) were spread on commercial diet. The feed was offered by 8 weeks. Results showed that fish fed experimental diets had no significant difference (P>0.05) in specific growth rates, condition factor, feed conversion ratios and survival compared with control. There were no significant difference (P>0.05) in moisture, crude protein, crude lipid and ash content of common carp fed diets containing various levels of plant extract. The mortality of fish challenged by Aeromonas hydrophila have been recorded for 30 days after challenging, results showed that mortality decreased significantly (P<0.05) in fish fed diet containing plant extract compared with the control. The lowest mortality observed in group fed diet containing 3% plant extract. Haematological parameters showed that white blood cells had significantly (P<0.05) increased in infected and uninfected groups compared with the control. Red blood cells, haemoglobin and haematocrit had no significant change (P>0.05) in infected and uninfected groups compared with the control.     

Stimulatory effect of dietary taurine on growth performance,digestive enzymes activity,antioxidant capacity,and tolerance of common carp, <Emphasis Type="Italic">Cyprinus carpio</Emphasis> L., fry to salinity stress

The present study was carried out to evaluate the effect of dietary taurine (Tau) on performance, digestive enzymes, antioxidant activity, and resistance of common carp, Cyprinus carpio L., fry to salinity stress. Fish (0.97?±?0.033 g) were fed on different taurine levels of 0.0 (control), 5, 10, 15, or 20 g/kg diet up to satiation twice daily for 8 weeks. At the end of the feeding trial, fish were stressed by exposure to 10 ppt salinity for 3 days during which fish mortality was observed. Fish performance was significantly (P?<?0.05) improved by dietary taurine up to 15 g Tau/kg diet after which fish growth and feed intake were almost the same. Also, taurine supplementation significantly (P?<?0.05) elevated activities of intestinal amylase, lipase, and protease resulting in an improving in feed intake giving better performance. Furthermore, Tau-stimulated antioxidant activity of common carp was observed in a dose-related manner, where activities of superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GPx) were significantly (P?<?0.05) higher, but malondialdehyde (MDA) value was significantly (P?<?0.05) lower in Tau-fed fish groups than those fed the control diet. In salinity stress experiment, highest survival rate was observed at fish fed Tau-supplemented diets without significant (P?>?0.05) differences over fish fed the control diet. It appears that taurine could be used as a feed supplement to confer better growth and health of common carp fry with optimal level of 15 g/kg diet.     

Dietary supplement of Enterococcus faecalis on digestive enzyme activities,short‐chain fatty acid production,immune system response and disease resistance of Javanese carp (Puntius gonionotus,Bleeker 1850)

This study investigated the effects of Enterococcus faecalis on digestive enzyme activities and short‐chain fatty acid production in fish intestine, resistance against Aeromonas hydrophila and humoral immunity response by 3 experiments on Javanes carp (Puntius gonionotus). The experiment 1 revealed that diet supplemented with E. faecalis significantly (P < 0.05) increased protease and lipase activities compared to control fed fish. Moreover, E. faecalis supplementation significantly enhanced the production of propionic and butyric acid in the intestine, while no significant difference (P > 0.05) in acetic acid production was observed. In the challenge study (experiment 2), fish were injected (intraperitoneal) with 10⁷ A. hydrophila per ml and survival was significantly improved when fish were fed diet supplemented with E. faecalis compared to control fish. In experiment 3, dietary E. faecalis affected immune system response as fish fed the probiont and exposed to 10⁶ A. hydrophila per ml displayed significantly elevated antibody levels compared to control fed fish. Fish fed diet supplemented with E. faecalis but not exposed to the pathogen revealed significantly higher antibody level than control fish (P < 0.05). Therefore, E. faecalis can be used as a probiotic in Javanese carp farming.     

Effect of dietary hydrolysate supplementation on growth performance,non‐specific immune response and disease resistance of olive flounder (Paralichthys olivaceus) challenged with Edwardsiella tarda

A 9‐week feeding trial was conducted to investigate the effects of dietary supplementation with protein hydrolysates on growth, innate immunity and disease resistance of olive flounder. A fishmeal (FM)‐based diet was regarded as a control, and three diets were prepared by partial replacement of FM with krill hydrolysate, shrimp hydrolysate or tilapia hydrolysate (designated as Con, KH, SH and TH, respectively). Triplicate groups of fish (24.5 ± 0.3 g) were fed one of the diets to apparent satiation twice daily for 9 weeks and then challenged by Edwarsellia tarda. Fish‐fed KH diet showed significantly (P < 0.05) higher growth performance and feed utilization compared with the Con diet. Dry matter digestibility of the diets was significantly increased by KH and TH supplementation. All the examined innate immune responses were significantly increased in fish fed KH diet. Significantly, higher respiratory burst and superoxide dismutase (SOD) activities were found in fish‐fed SH diet. Lysozyme and SOD activities were significantly increased in fish‐fed TH diet. However, no significant effect was found on fish disease resistance. This study indicates that dietary supplementation of the hydrolysates, particularly KH, can improve growth performance, feed utilization and innate immunity of olive flounder.     

Effects of glutamate in low‐phosphorus diets on growth performance,antioxidant enzyme activity,immune‐related gene expression and resistance to Aeromonas hydrophila of juvenile mirror carp (Cyprinus carpio)

This study investigated the effects of glutamate (Glu) in low‐phosphorus diets on growth performance, haematological indices, antioxidant enzyme activity, immune‐related gene expression and resistance to Aeromonas hydrophila in juvenile mirror carp (Cyprinus carpio) (5.07 ± 0.02 g). Fish were fed either graded levels of Glu (0 g/kg, 5 g/kg,  10 g/kg and 20 g/kg, named G0, G0.5, G1 and G2, respectively) in a low‐phosphorus diet (15 g/kg NaH₂PO_4, 0.49), or a normal phosphorus diet ( 20 g/kg NaH₂PO_4, 0.61) without added Glu (C), for 8 weeks. At the end of the feeding trial, the fish were challenged with A. hydrophila. Compared with G0 group, 10 g/kg and 20 g/kg Glu supplementation of the low‐phosphorus diet significantly improved the final weight, WGR, SGR and PER, and decreased FCR (p < .05). Glu supplementation of the low‐phosphorus diet significantly enhanced the T‐AOC, SOD activity and GSH content in intestine (p < .05). Glu supplementation significantly reduced MDA content in foregut and midgut and increased CAT activity in midgut and hindgut (p < .05). Regarding immune‐related gene expression, Glu supplementation significantly diminished the up‐regulation of intestinal TNF‐α, IL‐1β and IL‐8 mRNA levels induced by phosphorus deficiency (p < .05). The survival rate of the G1 group was significantly higher than that of the G0 group (p < .05). In conclusion, 10 g/kg Glu supplementation in low‐phosphorus diets can improve the growth performance, enhance the activity of intestinal antioxidant enzymes and strengthen the immune function of juvenile mirror carp.     

Studies on the Growth of Common Carp, Cyprinus carpio L., in a Lake Fishery

Data are presented on the growth of an artificially stocked population of common carp, Cyprinus carpio L. in a South Lancashire rod and line lake fishery. The fish could not be aged from their scales and methods are described for the analysis of directly measured annual growth increments for tagged fish of unknown age in three size classes. Mean growth in weight for carp in the 454–2268 g (1–5 lb) and 2268–4536 g (5–10 lb) size classes was 0.23 and 0.19 kg year^?1; mean annual length increments were 10.8 and 4.4 mm, respectively. Carp >4536 g were observed to lose weight and length at a mean annual rate of 0.17 kg and 3.7 mm. The implication of these results to the stocking policy for the lake are discussed in conjunction with previously reported data on stock density and catchability. Comparisons between June/July length-weight regressions for carp at the time of tagging and after 1 and 2 years indicated no significant differences. Causes of growth inhibition by tagging reported by other authors are examined and considered to have been eliminated from the current study in which no adverse influence on growth could be detected. The effects of population density, competition with other species, chemical factors, weed growths and angling pressure on the growth rates of the carp are discussed and their implications to the management of the fishery considered.     

Dietary medicinal herbs improve growth and some non-specific immunity of red sea bream <Emphasis Type="Italic">Pagrus major</Emphasis>

The effects of dietary medicinal herbs on growth and some non-specific immunity were investigated in juvenile red sea bream Pagrus major. The fish (mean body weight 24.0±0.2g) were fed fishmeal diets supplemented with either Massa medicata (Mm), Crataegi fructus (Cf), Artemisia capillaries (Ac), Cnidium officinale (Co), or a mixture of all the herbs (HM), and a control diet without medicinal herbs, for 12 weeks. Survival, specific growth rate, feed efficiency, condition factor and hemoglobin levels were higher in fish given herbal diets than fish given the control diet without herbs. Significantly higher serum high density lipoprotein-cholesterol level and lysozyme activity were detected in HM and Co diet groups, and alternative complement pathway activity was detected in the HM diet group. However, significantly lower serum alanine aminotransferase and aspartate aminotransferase activities were obtained in all herbal diet groups compared with the control diet group. Pathogen challenge test by intraperitoneal injection of Vibrio anguillarum indicated that highest survival was obtained in the HM diet group followed by Ac, Co, Cf, and Mm diet groups. The lowest survival was obtained in the control group. These results reveal that medicinal herbs in diets enhance growth and some non-specific immunity of red sea bream.     

Lemon,Citrus aurantifolia,peel and Bacillus licheniformis protected common carp,Cyprinus carpio,from Aeromonas hydrophila infection by improving the humoral and skin mucosal immunity,and antioxidative responses

The role of dietary lemon peel (LM) and/or Bacillus licheniformis (BL) on the growth, immunity, and resistance against Aeromonas hydrophila in common carp, Cyprinus carpio was investigated in this study. LM and BL were included in diets at 0% (T0), 10⁸ CFU/g BL (T1), 1.5% LM and 10⁸ CFU/g BL (T2), and 3% LM and 10⁸ CFU/g BL (T3). Fish fed with T1, T2, or T3 had higher weight gain, specific growth rate, white blood cells count, and blood total protein with lower feed conversion ratio than T0 group (p < .05). The albumin increased significantly (p < .05) in fish fed both BL and LM (T3). The serum superoxide dismutase (SOD), catalase, lysozyme, and bactericidal activities were significantly increased in fish fed both BL and LM (T2 and T3), while serum glutathione peroxidase increased in fish fed BL (T2) (p < .05). Fish fed T1, T2, and T3 diets displayed higher SOD and lower malondialdehyde than fish fed T0 (p < .05). After the A. hydrophila challenge, the mortality rate was significantly lower in T1, T2, and T3 groups than the T0 group (p < .05). The obtained results revealed that LM and BL could be used to increase resistance against A. hydrophila infection in carp. However, further field studies should be performed to confirm the obtained results.     

Effects of Dietary Supplementation of Barodon on Growth Performance,Innate Immunity and Disease Resistance of Juvenile Olive Flounder,Paralichthys olivaceus,Against Streptococcus iniae

This study was conducted to evaluate the effects of dietary supplementation of Barodon, an anionic alkali mineral complex, on growth, feed utilization, humoral innate immunity and disease resistance of olive flounder. A basal experimental diet was used as a control and supplemented with 0.1, 0.2, 0.3, 0.4, or 0.5% Barodon. Triplicate groups of fish (26.4 ± 0.2 g) were fed one of the diets to apparent satiation twice daily for 10 wk. The growth performance was enhanced (P < 0.05) linearly and quadratically in fish fed diets containing Barodon compared with that in fish fed the control. Feed utilization was significantly improved by Barodon supplementation. Serum lysozyme and antiprotease activities were increased quadratically in Barodon fed groups. Also, significantly higher superoxide dismutase activity was found in Barodon‐fed fish. Dietary supplementation of 0.1–0.3% Barodon resulted in significant enhancement of fish disease resistance against Streptococcus iniae. The findings in this study indicate that dietary supplementation of Barodon can enhance growth, feed utilization, innate immunity, and disease resistance of olive flounder and that the optimum level seems to be 0.1% in diets.     

A combination of rapeseed,cottonseed and peanut meal as a substitute of soybean meal in diets of Yellow River carp Cyprinus carpio var

A feeding trial was conducted to evaluate the results of replacing soybean meal (SBM) with other blend plant protein (BP) (rapeseed meal, cottonseed meal and peanut meal) sources on growth, fish body composition, biochemical parameters, non‐specific immune index and gene expression of growth hormone/insulin‐like growth factor‐1 in Yellow River carp Cyprinus carpio. The results showed that the 600 g/kg replacement with BP in diet did not affect the growth performance of Yellow River carp, but the 800 g/kg SBM replacement diet could depress the growth of fish (p < .05). The 800 g/kg SBM replacement diet significantly impacted the superoxide dismutase, malondialdehyde contents, lysozyme, alanine aminotransferase and aspartate aminotransferase activities (p < .05). Fish fed 800 g/kg SBM replacement diet showed lowest insulin‐like growth factor 1 and highest growth hormone level than that of other diets (p < .05). Both gene expression levels of GH and IGF‐I in hepatic showed significant difference among dietary treatments (p < .05), and the lowest GH and IGF‐I mRNA level in liver were found in fish fed 800 g/kg SBM replacement diet (p < .05). In conclusion, no more than 600 g/kg SBM could be replaced by BP in diet of Yellow River carp without adverse effects on the growth performance. However, 800 g/kg SBM replacement with BP in diet inhibited the growth performance, affected some blood parameters and immune response index, and down‐regulated GH and IGF‐1 gene expression of liver in Yellow River carp. Further, GH level in serum was negatively correlated with GH mRNA level in liver; meanwhile, serum concentrations of IGF‐I were positively correlated with hepatic IGF‐I mRNA expressions.