Effect of brewer’s yeast on immune response of giant freshwater prawn, Macrobrachium rosenbergii, and its resistance to white muscle disease

The present study was conducted to find the effect of dietary brewer’s yeast on growth, survival, immune response, and resistance to white muscle disease in giant freshwater prawn, Macrobrachium rosenbergii. The brewer’s yeast was supplemented at graded levels 0, 5, 10, and 20?g per kg diet, and the experiment was conducted for 75?days. After the feeding trials, growth, survival, immune parameters like prophenoloxidase activity, respiratory burst, and total hemocyte count were assessed. The growth, specific growth rate, and survival were not found significantly different among the treatment and control groups “prophenoloxidase activity and respiratory burst” were found significantly different (p?<?0.05) among the treatment and control groups. The total hemocyte count was significantly different (p?<?0.05) among control and treatment groups. Cumulative percent survival was higher in M rosenbergii fed 1?% brewer’s yeast-supplemented diet when they were challenged with white muscle disease virus (MrNV (Macrobrachium rosenbergii nodavirus) and XSV (extra small virus)). The present work revealed that the incorporation of brewer’s yeast in the diet is effective in enhancing immune response and controlling the white muscle disease in M rosenbergii.     

Should only females of giant freshwater prawn Macrobrachium rosenbergii be selected in genetic improvement programmes?

Sexual dimorphism is widely observed in almost all farmed aquatic animal species but giant freshwater pawn (GFP) is unique, with males characterized by three main morphotypes (blue claw, orange claw and small males) and females by different reproduction status (ovary, berried egg and already‐spawned females). There has been reported evidence that the effect of male morphotype may have masked genetic variation in growth‐related traits, as a result the heritability for male body weight was lower than that estimated in female. A pending question has arisen whether selection should be made in female only. To answer this question, we used an 8‐year data set from a long‐term selection programme (2008–2015) for high growth in this species comprising 106,756 individuals that were offspring of 515 sires and 810 dams. The body weight data of female and male GFP or of each morphotype was treated as a separate trait and a multi‐trait approach was used to estimate genetic correlations for homologous traits between sexes and between morphotypes. Our analysis showed that there were little differences in the heritability estimates between female and male. In female, mature ovary individual displayed higher heritability than berried egg and already‐spawned females. For male, the heritability for blue claw, orange claw and small males were 0.11, 0.06 and 0.00 respectively. Between‐sex genetic correlation was moderate (0.55 ± 0.11) for body weight, suggesting that the trait expressions in female and male may be genetically different. In female, the genetic correlations for body weight among three female types were close to one (0.91–0.94). In contrast, the genetic correlations for body weight between male morphotypes especially between blue claw or orange claw and small males were low (0.15–0.25). Furthermore, we estimated genetic gain as the difference in least square means (LSM) or estimated breeding values (EBV) between the selection line and control group. The genetic gain in body weight was smaller in females than in males. It is concluded that there is no need to run separate breeding programme for female and male GFP. A combined selection using both female and male data can achieve selection response for body weight as demonstrated in the present study.     

PCR cloning and identification of the β-haemolysin gene of Aeromonas hydrophila from freshwater fishes in China

In this study, β-haemolysin gene (AHTPS30HEM) of Aeromonas hydrophila was cloned from diseased fish in mainland China. AHTPS30HEM gene (AB021152) resulted in a 1589 bp fragment which covers the open reading frame (ORF) in region 5–1486 coding for 493 amino acids. Multiple alignment of AHTPS30HEM with other β-haemolysin amino acid sequences showed 18 amino acid substitutions between AHTPS30HEM and A. hydrophila β-haemolysin. Although the ORF sizes between AHTPS30HEM and Aeromonas species are different, four cysteins and four potential N-glycosylation sites were conserved. To identify the β-haemolysin-producing virulent or pathogenic A. hydrophila, a specific PCR to amplify 208 bp target DNA of β-haemolysin gene was established. Twenty strains containing pathogenic A. hydrophila, Aeromonas sobria, Vibrio anguillarum, Cytophaga columnaris, Pseudomonas fluorescens, and Yersinia yuckeri were investigated by PCR. Based on the cloned β-haemolysin sequences, the specific PCR method for identification of the β-haemolysin gene of A. hydrophila was established, and surveyed on those samples. The results indicated that β-haemolysin-specific PCR might be useful in the detection of pathogenic A. hydrophila.     

Effect of long-term administration of dietary β-1,3-glucan on growth, physiological, and immune responses in Litopenaeus vannamei (Boone, 1931)

β-1,3-Glucan at different dietary doses was administered to enhance the growth, immunity, and survival against nitrite stress in Pacific white shrimp, Litopenaeus vannamei. Four different diets supplemented with 0, 250, 500, or 1,000 mg of β-1,3-glucan kg⁻¹ diets were fed to L. vannamei. Growth performance (weight gain and survival rate), physiological conditions (blood total protein, glucose, lactate, triacylglycerols, cholesterol levels) and immunological responses (superoxide dismutase, catalase, lysozyme, acid phosphatase, and alkaline phosphatase activities) of shrimp were recorded after 84-day feeding and 120 h after exposed to nitrite-N. After 84-day feeding, 250 mg kg⁻¹ β-1,3-glucan diet resulted in better weight gain (P < 0.05). Before the nitrite stress, blood lactate, triacylglycerols, and cholesterol level in shrimp fed with 250 mg kg⁻¹ β-1,3-glucan diet were significantly higher than those observed in shrimp fed with other diets (P < 0.05). Higher activities of catalase, lysozyme, and alkaline phosphatase were observed in shrimp fed with 500 or 1,000 mg kg⁻¹ β-1,3-glucan diet as compared to those obtained in shrimp fed with other diets (P < 0.05). After 120-h nitrite stress, blood protein, lactate, superoxide dismutase, catalase, and alkaline phosphatase activities in shrimp fed with 500 or 1,000 mg kg⁻¹ β-1,3-glucan were significantly higher than those observed in shrimp fed with other diets (P < 0.05). Glucose and triacylglycerol levels of shrimp fed with 500 or 1,000 mg kg⁻¹ β-1,3-glucan were significantly lower than those observed in other diets (P < 0.05). In shrimp fed with 500 and 1,000 mg kg⁻¹ β-1,3-glucan and 120-h after nitrite stress, the mortality was significantly lower than that observed in shrimp of control. Together, in this 84-day feeding trial, 250 mg kg⁻¹ β-1,3-glucan improved growth, whereas 500 mg kg⁻¹ β-1,3-glucan preferentially improved nitrite resistance, probably through accelerating energy metabolism and activating immune system.     

Immunoadjuvant effect of garlic (Allium sativum)–mineral oil suspension on immunity and resistance to Aeromonas hydrophila infection in rohu,Labeo rohita

The immunomodulatory effect of garlic–mineral oil as a modified adjuvant was investigated in rohu, Labeo rohita along with formalin-killed Aeromonas hydrophila. The garlic extract was not having any proteolytic effect on the tested antigen as marked in SDS-PAGE. The efficacy of graded levels of modified adjuvant formulation was assessed by measuring serum hemolysin and agglutination titers as well as level of protection against A. hydrophila challenge in the immunized fish at days 10 and 30 post-vaccination (dpv). The higher hemolysin and bacterial agglutinin titers along with significantly lower mortality against A. hydrophila challenge in modified adjuvant-based vaccinated fish, particularly at low level of garlic incorporation, indicated the pronounced immunoadjuvant role of this modified adjuvant formulation in rohu.     

Impact of phased harvesting on population structure,feed intake pattern and growth performance of <Emphasis Type="Italic">Macrobrachium rosenbergii</Emphasis> DeMan (giant freshwater prawn) in polyculture with carps in concurrent rice–fish culture

This study was carried out to study the impact of phased harvesting on the population structure, feed intake pattern and growth performance of Macrobrachium rosenbergii in polyculture with carps in a deepwater rice–fish system. There were two experimental conditions—rice–fish culture with phased harvesting (T₁) and rice–fish culture without phased harvesting (T₂)— and a control, which consisted of rice monoculture without fish (T₃). In the T₁ trial, 61% of the population had a mean body weight (MBW) <20 g 120 days after stocking (DAS), which fell significantly to 7.3% at 210 DAS. However, in the T₂ trial, 62% of the population had a MBW <20 g at 120 DAS, which only fell to 23.7% at 210 DAS. Similarly, at 210 DAS, 12.5% of the population attained a MBW >80 g in the T₁ trial, while none of the population reached a MBW >80 g in the T₂ trial. The removal of fast-growing individuals in T₁ improved the prospects of other smaller individuals to achieve their individual growth potential. This step also disrupted the continuation of the socially induced differential growth rates, resulting in a wide variation in size within the population over time. The matrix of dietary overlap(s) of cultured species revealed that the degree of food preference was more similar between Cyprinus carpio and M. rosenbergii (0.9), while it overlapped poorly between Catla catla and M. rosenbergii (0.42). This high similarity index between bottom dwellers is evidence of the strong possibility that these bottom dweller compete for food. Natural and supplemental feed together with phased harvesting boosted the production of freshwater prawns (550 kg ha⁻¹) in the T₁ trial, while a 11.3% reduction in production was recorded in the T₂ trial.     

Identification of haematological markers in shrimp health assessment from the immune profile of Fenneropenaeus indicus on β-1,3-glucan administration and white spot syndrome virus challenge

Haematological alterations in Fenneropenaeus indicus fed marine yeast glucan-incorporated diet and challenged with white spot syndrome virus were analysed. Adult F. indicus 16.45 ± 2.12 g (mean ± SD) were reared in 25 ‰ sea water and allowed to acclimate for a period of 7 days. Diet was prepared incorporating glucan (0.2 %) extracted from marine yeast, Debaryomyces hansenii S169. The shrimps were reared on experimental diet for 28 days and then challenged with white spot syndrome virus through oral administration. Random sampling was done (n = 6 shrimps) on 1st, 15th and 28th day of the experiment and on post-challenge day 2 (PCD 2) and PCD 7 for haematological analysis. The immune parameters viz. plasma protein, total haemocyte count, phenoloxidase activity, superoxide anion production, alkaline phosphatase and acid phosphatase activities were estimated in the haemolymph. Superoxide dismutase, catalase, glutathione peroxidase, hydroperoxide, conjugated dienes and malondialdehyde concentrations in the haemolymph of shrimps were also analysed. Analysis of variance showed that there are significant differences (p < 0.05) in the immune and antioxidant parameters in different treatment groups of F. indicus. The shrimps fed glucan-incorporated diet showed higher survival rate with comparatively lower accumulation of lipid peroxidation products. Correlation coefficients showed that all haematological variables except hydroperoxides and conjugated dienes exhibited positive correlation with the survival rate. The immune variables and antioxidant parameters exhibited a greater degree of correlation with each other. When multiple regression of survival rate on all immune parameters was considered, the amount of variability explained was 93 % (R Square = 0.932). When significant regression coefficients among the immune parameters were taken into account, it was found that total haemocyte count (p < 0.001), phenoloxidase activity (p < 0.05), alkaline phosphatase activity (p < 0.05) and plasma protein concentration (p < 0.05) together are explaining 84 % (R ² = 0.842) of the variability, indicating that these four parameters are mainly supporting the survival. The amount of variability explained by the antioxidant parameters was 94 % (R ² = 0.938). When significant regression coefficients among the antioxidant parameters were taken into account, it was found that superoxide dismutase activity (p < 0.01) and catalase activity (p < 0.05) together are explaining 87.4 % (R ² = 0.874) of the variability, indicating that these two antioxidants act as the major immune effectors supporting the survival in shrimps.     

Inclusion of β-1,3/1,6-glucan in the ornamental fish,Jewel tetra (Hyphessobrycon eques), and its effects on growth,blood glucose,and intestinal histology

The effects of β-1,3/1,6-glucan on Hyphessobrycon eques were assessed after 42 days of feeding diets containing 0 (control group given commercial feed), 0.5, 1, or 2 g β-glucan/kg diet. In total, 180 fish, with an initial weight of 0.43?±?0.03 g, were used. There were 15 fish in each of twelve 42-L aquariums, and there were 3 aquariums of fish for each dietary treatment. The fish were fed until apparent satiety. Performance parameters (final weight, total length, standard length, feed intake, survival rate, weight gain, feed conversion, specific growth rate, and condition factor) and plasma glucose concentration were measured. Histological analysis of the proximal portion of the intestine (width and height of the villi, depth of the crypts, height of the enterocytes, thickness of the muscle layer, and number of goblet cells) was performed. Different levels of the additive did not influence fish performance (for example, final weight: control: 0.63 g, 0.5: 0.60, 1: 0.58, and 2: 0.61). Likewise, there was no influence on the plasma glucose concentration (control: 81.80 mg/dL, 0.5: 75.33, 1: 85.00, and 2: 81.00) and intestinal morphometry of the animals. However, the results showed that 2.0 g/kg of β-1,3/1,6-glucan provided a greater abundance of goblet cells secreting acidic and neutral mucus present in the epithelium (periodic acid-Schiff: 66.67 cells, Alcian blue pH 1.0: 72,67 cells, and Alcian blue pH 2.5: 95.00 cells), showing significant differences when compared to animals in the control group, which may represent better protection of the intestinal epithelium of H. eques.

     

Comparing the efficacy of dietary α-tocopherol with that of dl-α-tocopheryl acetate, both either alone or in combination with ascorbic acid, on growth and stress resistance of angelfish, Pterophylum scalare, juveniles

This study aimed to compare the efficacy of dietary α-tocopherol with that of dl-α-tocopheryl acetate, both either alone or in combination with vitamin C (ascorbic acid), on the growth performance, survival, and stress resistance of angelfish, Pterophylum scalare, juveniles. Juveniles were fed ad libitum for four weeks with Artemia enriched with no vitamins (control), vitamin C (T_c), α-tocopherol (T_α), dl-α-tocopheryl acetate (T _dl ), α-tocopherol and vitamin C (T_α+C), and dl-α-tocopheryl acetate and vitamin C (T _dl+C). After four weeks, an osmotic stress test was performed using seawater (25 g/L) to evaluate juvenile’s resistance to stress. Whole-body glucose and cortisol were used as stress indicators. At the end of the feeding trial, growth performance and survival of the juveniles fed vitamin-enriched Artemia were significantly (P < 0.05) higher than for the control fish. Best performance was recorded for the T_α+C group. Survival, however, was not significantly (P > 0.05) different between the vitamin-fed groups. Osmotic stress significantly elevated the stress indicators, whole-body cortisol and glucose levels (P < 0.05), highest and lowest values being observed in control and T_α+C groups, respectively. Survival after osmotic stress of juveniles fed the T_α+c diet was significantly higher (by 46.2%, P < 0.001) than for controls. Results suggested that α-tocopherol has greater efficacy than dl-α-tocopheryl acetate and enriching Artemia with α-tocopherol and vitamin C together improves growth performance, survival, and stress resistance of angelfish juveniles.     

Effect of high dietary carbohydrate on growth,serum physiological response,and hepatic heat shock cognate protein 70 expression of the top-mouth culter <Emphasis Type="Italic">Erythroculter ilishaeformis</Emphasis> Bleeker

To investigate the effects of different carbohydrate (CHO) levels in the diet of top-mouth culter Erythroculter ilishaeformis Bleeker, fish were randomly divided into five treatment groups. A control group was fed a diet with no CHO, and four treatment groups were fed with 14, 21, 27, and 34 % CHO, respectively, for 70 days. Serum cortisol level, glucose concentration, alanine aminotransferase activity, and malondialdehyde content of fish offered the diet containing 27 % CHO or 34 % CHO were significantly greater than those of fish offered the diet containing 14 % CHO or 21 % CHO. Serum lysozyme activity, total antioxidation capacity, and superoxide dismutase activity of fish offered the diet containing 27 % CHO or 34 % CHO also were significantly lower than those of fish offered the diet containing 14 % CHO. The relative levels of hepatic heat shock cognate protein 70 messenger RNA (mRNA) of fish offered the diet containing 27 % CHO after being deprived of food for 48 h or 34 % CHO at 48 h after feeding were significantly higher than those of fish offered the diet containing 21 % CHO or 14 % CHO. The results of this study suggest that ingestion of 27 or 34 % dietary CHO can impact the nonspecific immune ability of E. ilishaeformis and also cause metabolic stress.     

Effect of diethylstilbestrol (DES) and 17 β-estradiol (E2) on growth, survival and histological structure of the internal organs in juvenile European catfish Silurus glanis (L.)

The effect of supplemented commercial diets with diethylstilbestrol (DES—15, 30 and 60 mg kg^?1) and 17 β-estradiol (E2—30 and 60 mg kg^?1), two chemicals commonly used in sex reversal procedure in fish, on survival and growth parameters of juvenile European catfish (Silurus glanis) was evaluated. During the two experiments, lasting 28 days each, fish were kept at temperature 25.2–26.5 °C, pH 7.4–9.3 and oxygen concentration 5.0–7.3 mg O₂ dm^?3. DES supplementation resulted in depressed growth rate of catfish. In experimental groups fed with E2, no negative effect on growth parameters was found. Both chemicals did not result in observed mortality. In all of the experimental DES groups, hepatosomatic index increased significantly, which suggests negative influence on physiological condition of catfish. DES supplementation significantly changed cytological factors of liver cells and caused hepatic alterations in parenchyma, such as vacuolization and blood congestion. Similarly, supplementation of E2 in food resulted in changes in cytological parameters of hepatocytes. However, E2 did not cause pathological changes within the liver tissue. Histological examination of the catfish gonads showed 19 and 38 % of sterile fish after treatment with 30 and 60 mg kg^?1 of DES, respectively. The results suggest that DES served in food could be ineffective in hormonal feminization process of European catfish. No disturbances of sex differentiation process after E2 treatment were observed. However, slight feminization effect in the highest level of E2 treatment group was recorded.     

The Effect of Continual,Nocturnal, or No Aeration on Water Chemistry and Plankton Standing Crops in Highly-Fertilized Sunshine Bass,Morone chrysops × M. saxatilis,Fingerling Production Ponds Without Fish

ABSTRACT

Production of fingerlings from very small fry depends upon an initial high concentration of rotifers followed by high densities of crustacean zooplankton. High fertilization rates lead to increased zooplankton production but often cause poor water quality conditions that aeration may alleviate. This study was designed to determine the effects of constant, nocturnal, and no aeration on water quality, primary productivity, and standing crops of phytoplankton and zooplankton in heavily fertilized nursery-size ponds that contained no fish.

Four 0.04-ha ponds were aerated continually; four ponds were aerated only at night with a 372-W (1/2 hp) paddlewheel aerator; and four ponds were not aerated. For 21 days after they were filled on July 21, 1999, the ponds received 1,224 kg/ha rice bran and 581kg/ha liquid 9-27-0 fertilizer. Water quality variables, primary production, chlorophyll-a and zooplankton were sampled daily.

Constant aeration resulted in several conditions more conducive to survival of fish fry, such as higher zooplankton densities, more moderate temperatures, and safer dissolved oxygen levels than did nocturnal aeration or no aeration. However, the development of a higher standing crop of phytoplankton and higher total ammonia concentrations in the turbulent, constantly aerated ponds resulted in higher un-ionized ammonia levels that were not favorable to survival and growth of fry. The high concentrations of zooplankton that developed in the aerated ponds have good potential for cropping to inoculate other ponds or to provide live foods for tank culture of zooplanktivorous fish.     

Effect of dietary niacin on growth and body composition of two Indian major carps rohu, <Emphasis Type="Italic">Labeo rohita</Emphasis>, and mrigal, <Emphasis Type="Italic">Cirrhinus mrigala</Emphasis> (Hamilton), fingerlings based on dose–response study

An 15 week two set of feeding experiments were conducted to determine the dietary niacin requirement of Indian major carp fingerlings Labeo rohita and Cirrhinus mrigala, using casein gelatin–based diet. In both experiments, six isonitrogenous (40%) and isoenergetic (15.35 kJ g⁻¹) test diet, with graded levels of niacin (0–50 mg kg⁻¹ dry diet) in gradation of 10 mg kg⁻¹ dry diet, were formulated. In first experiment, fingerling of L. rohita (4.20 ± 1.22 cm; 0.632 ± 0.67 gm) were randomly stocked, in triplicate groups, in 55-L indoor polyvinyl flow-through system (1.5 L min⁻¹) and fed experimental diet at 0800 and 1600 h. Maximum live weight gain (1214%), feed conversion ratio (1.55) and protein efficiency ratio (1.60) were recorded at 30 mg dietary niacin diet. In second experiment, C. mrigala (4.50 ± 1.25 cm, 0.665 ± 0.88) were stocked in same setup. At the end of experiments, maximum live weight gain (1248%), FCR (1.47) and PER (1.70) occurred at 30 mg dietary niacin diet. However, the weight gain, FCR and PER data were analyzed by polynomial regression analysis indicating the requirement of niacin for L. rohita at 36.69, 33.06 and 32.0 mg kg⁻¹, respectively, and for C. mrigala at 35.19, 28.69 and 27.70 mg kg⁻¹ of dry diet, respectively. Whole body composition also showed significant (P < 0.05) differences among each other. On the basis of regression analysis of growth data, it is recommended that the diet for fingerlings should contain niacin at 33 and 30 mg kg⁻¹ dry diet for L. rohita and C. mrigala, respectively.     

Effect of temperature decrease on oocyte development,sex steroids,and gonadotropin β-subunit mRNA expression levels in female Japanese eel <Emphasis Type="Italic">Anguilla japonica</Emphasis>

To improve understanding of the mechanism of early ovarian development in eels, the effects of water temperature decrease on oocyte development, plasma levels of sex steroids [estradiol 17β (E2), testosterone (T), 11-ketotestosterone (11-KT)], and gonadotropin β-subunit [follicle-stimulating hormone (FSHβ), luteinizing hormone (LHβ)] messenger RNA (mRNA) expression levels were investigated. A total of 27 female Japanese eels Anguilla japonica were divided into initial, control, and test (water temperature decrease) groups. Starting on 22 September 2009, eels in the test group were reared in a tank with gradual temperature decrease from 25°C to 15°C over 39 days, while the control group was maintained at 25°C. The test group accumulated more oil droplets in their oocytes than did the other groups. Levels of sex steroids, especially 11-KT, were higher in the test group. In contrast, FSHβ and LHβ mRNA expression levels were lower in the test group. These results suggest that water temperature decrease only induced an early stage of ovarian development that was partly affected by an 11-KT increase. For further maturation, other environmental factors related to induction of gonadotropin increase appear to be needed.     

Effect of Stocking Density on Growth and Survival of the Rainbow Pearl Oyster <Emphasis Type="Italic">Pteria sterna</Emphasis> (Gould 1852) during Nursery and Late Culture in Bahía de La Paz,Baja California Sur,México

Growth and survival of the rainbow pearl oyster, Pteria sterna (Gould 1852), was evaluated in field culture at Bahía de La Paz, México. Mexican made Nestier^TM trays were used in nursery culture from March to July 1999 at four different stocking densities (25, 50, 75 and 100 individuals/tray). Late culture proceeded from July 1999 to March 2000 in sandwich nets and rail cages. Each artifact received 70 to 75 individuals. We studied the long-term effect of nursery culture stocking treatments. Growth patterns were examined using shell volume (height × width × depth, in cm³). Survival was estimated monthly. Growth and survival were acceptable regarding routine operations, but variations in this experiment depended on stocking density and type of late culture device. The interaction of density and culture device was significant for shell volume at the end of the experiment (F = 3614.14; p < 0.0001). Final shell volume depended on stocking density in nursery culture (F = 8.09, p < 0.001), but culture device had no influence (F = 0.76; p = 0.3). The results indicated that growth and survival in nursery culture were not proportionally related with stocking density. The change to late culture improved overall response. Advantages in growth were favorable for D50 C only. Rail cages promoted better survival than sandwich nets. Based on the natural behavior of P. sterna, the Optimal Stocking Density may be higher than the ranges tested in the present study. We recommend new strategies to improve the actual culture technology for P. sterna. A 3-dimensional culture unit might be an important advantage for this species regarding territorial exploitation and efficiency of spatial management in the production cycle.