Evaluation of Lactobacillus plantarum as a water additive on host associated microflora,growth, feed efficiency and immune response of giant freshwater prawn,Macrobrachium rosenbergii (de Man, 1879)

A 90‐day experiment was conducted by rearing 1020 prawn juveniles (0.54 ± 0.03 g) in water supplemented with three different concentrations of probiotic bacteria viz. T1 (10⁷ cfu L^?1), T2 (10⁸ cfu L^?1), T3 (10⁹ cfu L^?1) and the control (C) (unsupplemented water), to evaluate probiotic effect of Lactobacillus plantarum. In the present study, the growth parameters (WG%, SGR) and feed utilization parameters (FCR, PER) significantly improved (P < 0.05) in T3. The growth and feed utilization parameters though improved marginally in T1 and T2, the difference was not significant (P > 0.05) compared to the control. The gastro‐intestinal Lactobacillus sp. count increased significantly (P < 0.05) in all the treatment groups, whereas the decrease in harmful bacteria was significant (P < 0.05) in T3 compared to the control. Similarly, the Lactobacillus sp. count in culture water increased significantly (P < 0.05) in all the experimental groups, whereas the decrease in harmful bacteria was significant (P < 0.05) in T2 and T3. The immune parameters (THC, PO and RB activity) and clearance efficiency significantly improved (P < 0.05) in T3 with concurrent decrease (P < 0.05) in cumulative mortality against Aeromonas hydrophila challenge. However, water quality did not improved (P > 0.05) in any of the treatment groups. The results indicate that Lactobacillus plantarum at a minimum concentration of 10⁹ cfu L^?1 could be used as water additive to confer its probiotic effect in prawn, Macrobrachium rosenbergii. Moreover, future studies with higher probiotic concentrations should be conducted for its efficient commercial scale field application.     

Growth and production of endangered Indian butter catfish,Ompok bimaculatus (Bloch) at different stocking densities in earthen ponds

Growth, survival and production of endangered Indian butter catfish (Ompok bimaculatus) fingerlings were examined at different stocking densities. The experiment was conducted for 8 months in nine earthen ponds having an area of 0.03 ha each. 30‐day‐old fingerling, stocked at 40 000 ha^?1 was designated as treatment‐1 (T1), 50 000 ha^?1 as treatment‐2 (T2) and 60 000 ha^?1 as treatment‐3 (T3). At stocking, all fingerlings were of same age group with a mean length and weight of 3.36 ± 0.08 cm and weight of 0.83 ± 0.02 g respectively. Fish in all the treatments were fed with a mixture of rice bran (50%), mustard oil cake (30%), fish meal (19%) and vitamin‐mineral premix (1%). Physicochemical parameters, plankton populations and soil parameters were at the optimum level for fish culture. Highest weight gain was observed in T1 and lowest in T3. Final length, weight and survival of fish also followed the same trend as weight gain. Highest specific growth rate was observed in T1 followed by T2 and T3. Feed conversion ratio was significantly lower in T1 followed by T2 and T3 in that order. Significantly higher amount of fish was produced in T1 than T2 and T3 respectively. Higher net benefit was obtained from T1 than from T2 and T3. Overall, the highest growth, survival and benefit of fish were obtained at a density of 40 000 fingerlings ha^?1. Hence, of the three stocking densities, 40 000 fingerlings ha^?1 appears to be the most suitable stocking density for culturing of Indian butter catfish in grow‐out system.     

Impact of neem (Azadirachta indica A. Juss) seed cake upon selective nutrient cycling bacterial population in fish culture

With an objective to examine neem seed cake as bactericide, three treatments—10, 20, and 30 mg L^?1—were applied in outdoor experimental Labeo rohita culture tanks for a period of 120 days. Nitrifying, ammonifying, and denitrifying bacteria declined directly with increasing dosage. Ammonifying and phosphate solubilizing bacteria recovered within a month, nitrifying and denitrifying bacteria after 45 days. A positive relationship was established between soil available-N and ammonifying, nitrifying, and denitrifying bacteria in 10 mg L^?1 (R² = 0.68–0.83). Phosphate solubilizing bacteria responded directly with dosage and contributed significantly to the orthophosphate pool (R² = 0.66–0.78).     

Dietary ascorbic acid requirement for growth of striped catfish,Pangasianodon hypophthalmus (Sauvage, 1878) juveniles

A sixty‐day feeding trial was conducted to determine the ascorbic acid (AA) requirement for growth of striped catfish, Pangasianodon hypophthalmus juveniles. Seven iso‐nitrogenous and iso‐energetic (370 g protein per kg and 19.6 MJ/kg) purified diets were prepared with different levels of ascorbic acid such as control (0), T₁ (17.5), T₂ (35), T₃ (70), T₄ (175), T₅ (350) and T₆ (700) mg ascorbic acid (L‐ascorbyl‐2‐polyphosphate) equivalent per kg diet. Fish with a mean body weight of 3.2–3.4 g were stocked (fifteen fish per tank) in triplicates following a completely randomized design. Each group was fed to satiation twice a day for 60 days. Significant differences were observed in growth, survival, body composition and metabolic enzymes activities with different dietary ascorbic acid levels. Maximum weight gain, specific growth rate (SGR) and protein efficiency ratio (PER) were found in fishes fed with 35 mg AA per kg diet, supported by best feed conversion. Fish fed a diet containing vitamin C had the highest activities of aspartate aminotransferase (AST), alanine aminotransferase (ALT) and alkaline phosphatase (ALP) compared to those fed with vitamin C‐depleted diets. In this study, based on using broken‐line regression analysis, the dietary vitamin C requirement for growth of P. hypophthalmus juveniles was estimated to be in the range of 46–76 mg AA per kg, depending on the criterion used, growth and liver storage. Our results will be helpful for the formulation of cost‐effective ascorbic acid incorporated diets for striped catfish, P. hypophthalmus.     

Development of a simple and rapid monoclonal antibody-based flow through immunogold assay (FIA) for detection of <Emphasis Type="Italic">Aeromonas hydrophila</Emphasis>

In this study, we developed a simple, low-cost, and rapid flow through immunogold assay (FIA) for detection of Aeromonas hydrophila in fish tissues and validated. The developed assay relied on colloidal gold conjugated highly specific monoclonal antibody (B8E3) against 20 kDa protein of A. hydrophila. The assay can be completed within 5 min including antigen (sample) preparation and exhibited no cross-reaction with other major aquatic pathogens such as Vibrio anguillarum, V. parahaemolyticus, V. harveyi, white spot syndrome virus (WSSV), and Aphanomyces invadans. A wider range of Aeromonas species were tested including A. caviae, A. dhakensis, A. sobria, A. veronii, A. culicicola, A. sharmana, and A. schubertii and no cross-reactivity could be observed. The developed technique FIA could detect 10³ CFU/ml of aeromonad cells. In addition, the FIA is as sensitive as the first-step polymerase chain reaction (PCR) and 1000 times sensitive than the immunodot blot method. The validation study revealed the accuracy of FIA by comparing with the standard first-step PCR. The proposed FIA is low-cost, easy-to-use, and compatible for field-level analysis of A. hydrophila in fish tissues. Our developed FIA could successfully detect A. hydrophila at early stage of the infection and could be easily availed by farmers, fish producers, non-technicians, and technicians in the aquaculture industry.     

Improving fertilizer recommendations for Nepalese farmers with the help of soil-testing mobile van

Smallholder farmers dominate agriculture in Nepal. These farmers have poor knowledge about agriculture and lack of support for soil management and integrated plant-nutrient systems. Focusing on the importance and need for soil-fertility management, a soil-testing mobile van program has recently been introduced in Nepal by Soil Management Directorate, Hariharbhawan. With the introduction of the mobile lab, famers can get their soil tested for nutrient deficiencies and fertilizer requirements at their doorsteps. Using mobile lab, spatial distributions of chemical properties, including pH, organic matter (OM), total nitrogen (N), available phosphorus (as P₂O₅), and available potassium (as K₂O) were examined in soil samples taken from the 0 to 15 cm depth from selected agricultural fields in eight different districts in the mid-hills and Terai regions of Nepal. Tests conducted on 1,479 soil samples in the soil-testing mobile van revealed the following: the mean soil OM ranged from 0.01 to 1.77%; total N content ranged from 0.01 to 0.08%; mean available P₂O₅ ranged from 16.47 to 197.82 kg ha^?1; and mean available K₂O ranged from 84.3 to 422.57 kg ha^?1. For each crop to be grown, farmers were provided with individual soil health reports and fertilizer recommendations (rate, amount, and type). This program not only allows scientists and farmers to work closely and share information but also serves as a model for the nation to successfully transfer technology for improving soil health and sustainability.     

Effect of dietary Sargassum wightii and its fucoidan-rich extract on growth,immunity, disease resistance and antimicrobial peptide gene expression in Labeo rohita

International Aquatic Research - This work aimed to appraise growth performance, immune responsiveness, bacterial disease resistance and mRNA expression of two antimicrobial peptides in Labeo...     

Statistical Assessment of Sustainability of Finger Millet Yield through Rainfall and Soil Fertility Variables using Regression and Principal Component Models in Rainfed Semi-Arid Alfisol

Field experiments were conducted in farmyard manure (FYM) and maize-residue (MR) blocks during 1984–2011 with the objective of identifying a superior treatment for attaining maximum finger millet yield and soil fertility at Bangalore. The treatments tested in the FYM block were Control; FYM@10tha^?1; FYM@10tha^?1 + 50% nitrogen, phosphorus, and potassium (NPK); FYM@10tha^?1 + 100%NPK; 100%NPK; and in the MR block, Control; MR@5tha^?1; MR@5t ha^?1 + 50%NPK; MR@5tha^?1 + 100%NPK; 100%NPK. FYM@10t/ha + 100%NPK gave a maximum mean yield of 3207 kg/ha in the FYM block, while MR@5t/ha + 100%NPK gave 2548 kg/ha in the MR block. Regression and principal component (PC) models of yield were developed through soil fertility and rainfall variables to assess the treatments. Maximum yield predictability of 60% and 65% under regression, and 76% and 75% under the PC model were observed for the FYM and MR blocks, respectively. FYM@10t/ha + 50%NPK was superior, with maximum gross returns of Rs.41286/ha and benefit–cost ratio (BCR) of 2.27 in the FYM block compared to MR@5t/ha + 100%NPK (gross returns of Rs.34530/ha and BCR of 2.09) in the MR block with maximum soil fertility, and are recommended for adoption under semi-arid Alfisols.     

Effect of Integrated Nutrient Management on Soil Fertility and Yield of Rice (Oryza sativa L.) under the System of Rice Intensification in the Indian Subtropics

Field experiments were conducted at Water Management Research Station, Begopara, Nadia, WB, India, during the rabi seasons of 2008–2009 and 2009–2010 to find out the integrated effect of nitrogen (N), phosphorus (P), potassium (K), farmyard manure (FYM) and zinc (Zn) under the system of rice intensification (SRI) techniques using eight treatments on the fertility changes in soil. The results revealed that the amounts of organic carbon and available N content in soil were found to maintain the highest fertility status with the highest yield in T₆ (NPK + FYM 10 tha^?1 + Zn 5 kgha^?1) and gave the highest N uptake (55.98 kgha^?1). The availability of P decreased with the increased level of Zn application and gave the highest P uptake (23.52 kgha^?1) in the treatment T₅ (NPK + FYM 10 tha^?1). The highest Zn content (4.71 mgkg^?1) was recorded in the treatment T₇ (NPK + FYM 10 tha^?1+ Zn 10 kgha^?1).