Carcass traits of different marketable sizes of rohu,Labeo rohita (Hamilton, 1822)

The present study was carried out to investigate the carcass traits of farmed freshwater Labeo rohita in relation to body size as important information to calculate yield and/or support for machine/manual processing. For this purpose ninety specimens were collected for nine weight groups from 600 to 1100 g, each group with a 100 g increment. Specimens were collected from grow‐out culture ponds of the Central Institute of Freshwater Aquaculture (CIFA), Bhubaneswar. The carcass evaluation technique was followed to evaluate carcass yield, offal yield and carcass cutability. Head size percentage of rohu increased as the body mass increased, which in turn increased the processing yield. Dry matter and ether extract percentage also increased with the body mass; however, moisture percentage showed a decreasing trend. The fore cut showed a distinctly higher ether extract percentage followed by the middle and posterior cuts. There was a good correlation development to describe the relationship between yield traits and body weight.     

Effect of dietary beta-1,3 glucan on immune responses and disease resistance of healthy and aflatoxin B1-induced immunocompromised rohu (Labeo rohita Hamilton).

The immunostimulant beta-1,3 glucan was fed at 0.1% in feed for 7 days to healthy and aflatoxin B1 (AFB1)-induced immunocompromised fish, Labeo rohita (one of the major tropical carp species), in a 60 day trial. The effects of AFB1, glucan and their interactions on non-specific and specific immunity levels and disease resistance of fish were studied. A single intraperitoneal injection of AFB1 at 1.25 mg kg(-1) body weight) caused a significant (P < 0.05) reduction in non-specific immunity as measured through neutrophil phagocytic indices, serum bactericidal activity, and specific immunity as measured through bacterial agglutination titre against Edwardsiella tarda, as well as reduced protection against Aeromonas hydrophila challenge in comparison to control fish which were exposed neither to aflatoxin nor to glucan. Feeding of glucan to healthy fish raised the non-specific and specific immunity level and protection against bacterial infection compared with the control. Feeding of glucan to AFB1-induced immunocompromised fish for 7 days significantly raised the degree of resistance against A. hydrophila challenge and the non-specific immunity level in comparison to non-treated AFB1 exposed fish. Although feeding of glucan was able to increase specific immunity, all measured through haemagglutination titre against sheep red blood cells, and bacterial (E. tarda) agglutination titre in healthy fish in comparison to all other groups, no significant increase in specific immunity to the aflatoxin-exposed group was seen.     

High temperature acclimation alters upper thermal limits and growth performance of Indian major carp,rohu, Labeo rohita (Hamilton, 1822)

Increase in water temperature due to anthropogenic and climatic changes is expected to affect physiological functions of fish. In this study, we determined high temperature tolerance (CTmax) of a common aquacultured Indian major carp, rohu, Labeo rohita fingerlings (15.96 ± 0.72 g BW, 11.56 ± 0.42 cm TL) followed by acclimatization at three temperatures (30, 33, 36 °C). To determine the CTmax, we analyzed the major hemato-biochemical indices - hemoglobin (Hb), red blood cell (RBC), white blood cell (WBC), blood glucose levels, and erythrocytic nuclear abnormalities (ENAs) and erythrocytic cellular abnormalities (ECAs) of peripheral erythrocytes in the fish sampled at the start and end point at each acclimated temperature. Significantly decreased CTmax of the fish was found at 36 °C compared to 30 °C and 33 °C. The fish in the highest (36 °C) temperature were found with significantly lower Hb and RBC content and significantly higher WBC and blood glucose levels than that of the fishes in the lowest (30 °C) temperature both at the start and end points. The highest frequencies of ENAs and ECAs were found in the highest (36 °C) temperature group compared to the lowest (30 °C) temperature group at both the points. We also evaluated growth performance of the rohu fingerlings reared in the three temperatures for 60 days. The growth parameters - final weight gain, percent weight gain and specific growth rate were the highest at 33 °C and the lowest at 36 °C. The present study revealed that the highest temperature (36 °C) tested here may be hazardous to rohu and the temperature should be kept below 36 °C in the aquaculture setting to avoid physiological damage and growth and production loss to the fish.     

Effect of dietary protein and carbohydrate levels on growth,nutrient utilization and body composition in fingerling rohu,Labeo rohita (Hamilton)

Twelve experimental diets (D‐1 to D‐12) in a 4 × 3 factorial design having four protein levels (25, 35, 40 and 45%) and three carbohydrate levels (15, 25 and 35%) were formulated and fed to fingerling rohu, Labeo rohita (5.48 ± 0.02 g) for 60 days in three replicates at 2% BW per day. The best performance of fish in terms of weight gain (%), specific growth rate (SGR; % per day), feed conversion ratio (FCR) and protein efficiency ratio (PER) was recorded with diet D‐9 containing 40% protein and 35% dextrin as a source of dietary carbohydrate. In general, lower protein consumption per kilogram BW was observed at all protein levels with the rise of the dextrin level. The apparent digestibilities of protein and lipid were not affected by the dietary treatments. At the end of the experiment the body composition of animals from all treatments showed lower percentages of moisture and higher percentages of protein as compared to the initial values. A consistent rise in protein retention efficiency was noted in fish fed diets with increasing dextrin levels. The highest protein sparing effect was found in fish fed the diet containing 40% protein and 35% dextrin.     

Growth and body composition of rohu, Labeo rohita (Hamilton), fed compound diet: winter feeding and rearing to marketable size

A 122‐day growth trial was conducted to observe the impact of polyhouse in winter on growth, conversion efficiencies and body composition of fingerling Labeo rohita (7.9 ± 1.1 cm; 4.60 ± 0.18 g). Fish were stocked (1.5 m^?2) in polyhouse and outdoor concrete tanks (250 m²) in duplicate and fed a compound diet [35% crude protein (CP)] to apparent satiation twice daily, at 09.00 and 17.00 hours. A natural photoperiod was maintained during the trials. At the end of the trials, polyhouse‐reared fish produced significantly (P < 0.01) higher values for weight increment, specific growth rate (SGR %), protein efficiency rate (PER), protein productive value (PPV) and better feed conversion ratio (FCR). Polyhouse‐reared fish showed higher (P < 0.01) CP and fat, and lower (P < 0.01) moisture and ash contents in the muscle. In the second part of the study, which also lasted 122 days, polyhouse‐reared young L. rohita (21.7 ± 1.3 cm; 127.8 ± 0.69 g) were raised to marketable size in outdoor earthen ponds (500 m²) at a stocking density of 0.37 m^?2 to examine the effects of feeding traditional feed mixture and compound diet (30% CP) on growth and body composition of fish. Labeo rohita fed the compound diet showed higher (P < 0.01) values for weight increment, SGR (%), PER and PPV, and better (P < 0.01) FCR than those fed traditional feed. Proximate composition of fish muscle showed higher (P < 0.05) CP and fat, and lower (P < 0.05) moisture and ash contents in fish fed the compound diet. The results suggest that polyhouse may be used successfully to culture L. rohita during winter, and that thereafter the fish may be reared in earthen ponds using the compound diet to obtain better production.     

Nutritional evaluation of fermented black gram (Phaseolus mungo) seed meal in compound diets for rohu, Labeo rohita (Hamilton), fingerlings

Six isonitrogenous (approximately 35% crude protein) and isocaloric (approximately 4.0 kcal g⁻¹) diets were formulated incorporating raw and fermented black gram, Phaseolus mungo, seed meal at 20%, 30% and 40% levels by weight into a fishmeal‐based control diet fed to rohu, Labeo rohita, fingerlings (mean weight, 1.81 ± 0.21 g) for 80 days for a study of fish performance. A particular bacterial strain (Bacillus sp.) isolated from the intestine of adult common carp (Cyprinus carpio) reared in the wild having significant amylolytic, cellulolytic, lipolytic and proteolytic activities was used for fermentation of seed meal for 15 days at 37 ± 2°C. Fermentation of P. mungo seed meal was effective in significantly reducing the crude fibre content and antinutritional factors such as tannins and phytic acid, and enhancing available free amino acids and fatty acids. In terms of growth, feed conversion ratio and protein efficiency ratio, the 30% fermented black gram seed meal incorporated diet resulted in a significantly (P < 0.05) better performance of rohu fingerlings. In general, growth and feed utilization efficiencies of diets containing fermented seed meal were superior to diets containing raw seed meal. The apparent protein digestibility (APD) values decreased with increasing levels of raw seed meal in the diets. The APD for raw seed meal was lower at all levels of inclusion in comparison to those for the fermented seed meals. The maximum deposition of protein in the carcass was recorded in fish fed the diet containing 40% fermented seed meal. The results indicate that fermented black gram seed meal can be incorporated in carp diets up to the 30% level compared to the 10% level of raw seed meal.     

Dietary valine requirement of Indian major carp, Labeo rohita (Hamilton) fry

Dietary valine requirement of Indian major carp, Labeo rohita Hamilton, fry (3.0 ± 0.02 cm, 0.16 ± 0.03 g) was determined using dose‐response method. Fishes were fed six isonitrogenous [40% crude protein (CP)] and isocaloric (4.28 kcal g^?1, Gross Energy (GE)) amino acid test diets containing casein, gelatin, and l ‐crystalline amino acids with graded levels of valine (0.75, 1.00, 1.25, 1.50, 1.75, and 2.00% dry diet) at 5% body weight for 6 weeks in triplicate groups twice a day at 07.00 and 17.30 hours. Live weight gain (158.52%), feed conversion ratio (FCR, 1.70), specific growth rate (SGR, 2.25), and protein efficiency ratio (PER, 1.46) were significantly (P < 0.05) higher in fish fed a diet containing 1.5% of the dietary valine (diet IV). Second‐degree polynomial regression analysis of the live weight gain and FCR data indicated the dietary valine requirement at 1.63 and 1.5% of the dry diet, corresponding to 4.0 and 3.75% of dietary protein. Maximum carcass protein, minimum moisture, and fat were recorded at 1.5% of the dietary valine level, except carcass ash, which remained constant throughout the treatments. No mortality was observed during the entire length of the feeding trial. On the basis of FCR and protein deposition data, it is recommended that dietary valine inclusion at 1.5% of dry diet, corresponding to 3.75% of dietary protein, is optimal for the growth of L. rohita fry.     

Stage-dependent hatching responses of rohu (Labeo rohita) embryos to different concentrations of cryoprotectants and temperatures

Hatching performances of three embryonic stages of postfertilization rohu (Labeo rohita) (9-, 12-, and 15-h) were examined after treatment with various concentrations (0.5-4.5M) of two cryoprotectants (methanol and propylene glycol) supplemented with 0.1M trehalose. Different lengths of storage (1-48 h) and temperature (-4 degrees C to ambient) were studied. Of the three stages of embryonic development, the 12-h stage proved to be the most suitable stage for low temperature storage, showing the highest percentage of hatch out (72+/-2%) with 2.0M methanol and 0.1M trehalose. Methanol was more useful for storage at higher temperatures and propylene glycol at subzero temperatures. The maximum possible duration of effective storage of 12-h embryos was 31h in 2.0M methanol at 0 degrees C. No hatch out was found beyond 31h of storage with all concentrations of methanol at 0 degrees C. The results of interactions was that the optimal concentration of methanol was 3.0M at 4 degrees C, 2.0M at 0 degrees C, and 1.5M at 4 degrees C. Among three embryonic stages 12-h stage showed better results in trehalose treatment than sucrose. Among all concentrations of trehalose tested 0.1M gave the maximal survival rate of the rohu embryos.     

Hematological and plasma chemistry of Indian major carp,Labeo rohita (Hamilton, 1822)

Hematological and plasma chemistry indices are simple and essential diagnostic tools for monitoring the physiological and health status of fish. Aim of the present study was to obtain reference values for the hematological and plasma chemistry of wild populations of Labeo rohita captured in a freshwater pond between July 2008 and June 2010. These reference values and the mean were evaluated according to sex and season. In summer, the red blood cells (1.84 × 106 38 per cubic mm), haemoglobin (8.52 gm dl^?1) and haematocrit (31.49%) were highest in males, whereas the maximum values for white blood cells (5.635 × 103 40 per cubic mm) were found in females, however, no significant variation of mean corpuscular volume (MCV) or mean corpuscular haemoglobin (MCH) was observed between sexes. Various blood parameter levels between the sexes in summer were notably different from those measured in other seasons except for MCH and MCHC values (p < 0.05). Compared to most teleosts, the L. rohita has similar mean values for PCV and Hb. Throughout summer the glucose (76.0 mg dl^?1), lipid (3.41 gm dl^?1) and cholesterol (145.0 mg dl^?1) levels were highest. In spring the plasma protein levels were higher in males, but higher in winter for females. Consequently, the seasons are key factors when using blood parameters as biomarkers for environmental alterations.     

Thermal tolerance,growth and oxygen consumption of Labeo rohita fry (Hamilton, 1822) acclimated to four temperatures

A 30 day feeding trial was conducted using a freshwater fish, Labeo rohita (rohu), to determine their thermal tolerance, oxygen consumption and optimum temperature for growth. Four hundred and sixteen L. rohita fry (10 days old, 0.385±0.003 g) were equally distributed between four treatments (26, 31, 33 and 36 °C) each with four replicates for 30 days. Highest body weight gain and lowest feed conversion ratio (FCR) was recorded between 31 and 33 °C. The highest specific growth rate was recorded at 31 °C followed by 33 and 26 °C and the lowest was at 36 °C. Thermal tolerance and oxygen consumption studies were carried out after completion of growth study to determine tolerance level and metabolic activity at four different acclimation temperatures. Oxygen consumption rate increased significantly with increasing acclimation temperature. Preferred temperature decided from relationship between acclimation temperature and Q₁₀ values were between 33 and 36 °C, which gives a better understanding of optimum temperature for growth of L. rohita. Critical thermal maxima (CTMax) and critical thermal minima (CTMin) were 42.33±0.07, 44.81±0.07, 45.35±0.06, 45.60±0.03 and 12.00±0.08, 12.46±0.04, 13.80±0.10, 14.43±0.06, respectively, and increased significantly with increasing acclimation temperatures (26, 31, 33 and 36 °C). Survival (%) was similar in all groups indicating that temperature range of 26–36 °C is not fatal to L. rohita fry. The optimum temperature range for growth was 31–33 °C and for Q₁₀ values was 33–36 °C.     

The immunosuppressive effect of alpha-permethrin on Indian major carp, rohu (Labeo rohita Ham.)

The immunosuppressive effects of bath exposure to a sub lethal concentration of the synthetic pyrethroid alpha-permethrin (3.05 x 10(-4) mg l(-1)) in the Indian Major carp, Labeo rohita was studied after 45 days' exposure. In some groups, the effects of alpha-permethrin on non-specific defences and serum enzymes of carp were investigated after challenge with Aeromonas hydrophila. Several nonspecific immune responses and serum enzymes were reduced after exposure of alpha-permethrin. Bactericidal activity of rohu serum was reduced significantly in pesticide and bacteria treated fish. The Glutamic Oxaloacetate Transaminase (GOT) and Glutamic Pyruvate Transaminase (GPT) activity were increased in immunosuppressed fish. Blood glucose level was elevated significantly and Hb% was reduced significantly in pesticide and bacteria treated fishes as compared to the negative control.     

Isolation and characterization of immunoglobulin of the Indian major carp, rohu [Labeo rohita (Ham.)

Information on the structure and character of immunoglobulin of fishes is essential in health management. A study was carried out to characterize the serum immunoglobulin (IgM) of the Indian major carp, rohu Labeo rohita (Ham.). Rohu (500g) were immunised with bovine serum albumin (BSA) and the anti-BSA antibody was purified employing BSA-CL agarose affinity column chromatography. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) of the purified Ig in a 3% gel under non-reduced conditions revealed a single protein having a molecular weight of 850kDa. Analysis of the purified serum in 10% SDS-PAGE under reduced conditions revealed that the immunoglobulin contained heavy and light chains with molecular weights of 85 and 23kDa, respectively. A polyclonal mouse anti-rohu IgM was prepared and used in an immunodot test which showed a specific reaction of the crude rohu anti-BSA antiserum and the purified anti-BSA IgM with BSA. Results indicate that the immunoglobulin of L. rohita is tetrameric IgM, similar to that of other fishes.     

Development of monoclonal antibodies to rohu [Labeo rohita] immunoglobulins for use in immunoassays

Serum immunoglobulins [Ig] of rohu [Labeo rohita] were purified by affinity chromatography using bovine serum albumin as capture ligand. The purified rohu Ig [r-Ig] had a molecular weight [MW] of 880 kDa as determined with gel filtration chromatography. The heavy chain of r-Ig had an MW of 77.8 kDa and that of light chain was 26.4 kDa in SDS-PAGE. Purified r-Ig was used for the production of two anti-rohu Ig monoclonal antibodies [D7 and H4] that belonged to subclass IgG2b and IgG1, respectively. Both the MAbs were specific to heavy chain of r-Ig as seen in Western blotting. Anti-rohu Ig MAb was used as a diagnostic reagent in ELISA and immunocytochemical assays to demonstrate its application for sero-surveillance and for immunological studies in rohu. A competitive ELISA was used to demonstrate the antigenic relatedness of r-Ig with whole serum Ig of other fish species. Cross reactivity of anti-rohu Ig MAb was observed with serum Ig of Catla catla and Cirrihinus mrigala. No reactivity to serum Ig of Ophiocephalus striatus and Clarias gariepinus was seen. Anti-rohu Ig MAb was found to be suitable for the detection of pathogen specific [Edwardsiella tarda] antibodies in serum of immunized rohu by an indirect ELISA. In flow cytometry using D7 MAb, the mean percentage [+/-SE] of Ig positive cells in spleen and blood of rohu were found to be 64.85% [+/-2.34] and 51.84% [+/-2.55] of gated lymphocytes, respectively. Similarly, D7 MAb also stained 52.84% [+/-1.30] and 10.5% of gated lymphocytes in kidney and thymus, respectively. The anti-rohu Ig MAbs also showed specific staining of Ig bearing cells in spleen sections by the indirect immunoperoxidase test.     

Revealing liver specific microRNAs linked with carbohydrate metabolism of farmed carp,Labeo rohita (Hamilton, 1822)

The role of microRNA in gene regulation during developmental biology has been well depicted in several organisms. The present study was performed to investigate miRNAs role in the liver tissues during carbohydrate metabolism and their targets in the farmed carp rohu, Labeo rohita, which is economically important species in aquaculture. Using Illumina-HiSeq technology, a total of 22,612,316; 44,316,046 and 13,338,434 clean reads were obtained from three small-RNA libraries. We have identified 138 conserved and 161 novel miRNAs and studies revealed that miR-22, miR-122, miR-365, miR-200, and miR-146 are involved in carbohydrate metabolism. Further analysis depicted mature miRNA and their predicted target sites in genes that were involved in developmental biology, cellular activities, transportation, etc. This is the first report of the presence of miRNAs in liver tissue of rohu and their comparative profile linked with metabolism serves as a vital resource as a biomarker.     

Carbofuran- and cypermethrin-induced histopathological alterations in the liver of Labeo rohita (Hamilton) and its recovery

Alterations in the liver histology of Labeo rohita were examined after exposure to different concentrations of carbofuran (0.06 and 0.15 mg L^?1) and cypermethrin (0.16 and 0.40 μl L^?1) for 28 days. Histological recovery was also studied by maintaining the intoxicated fish in a freshwater system for an additional 28 days. Major damages caused by carbofuran toxicity were diffuse necrosis, cordal disarrangement, individualization of hepatocytes, etc.; significant changes induced by cypermethrin were hyperplasia, disintegration of hepatic mass, focal coagulative necrosis, etc. In both cases, damages were dose‐dependent, with cypermethrin exhibiting more sensitivity than carbofuran. In all cases, recovery was prominent and rate of recovery was faster with carbofuran than when using cypermethrin.