Spent brewer's yeast as a replacement for fishmeal in diets for giant freshwater prawn (Macrobrachium rosenbergii), reared in either clear water or a biofloc environment

A 90‐day feeding experiment was conducted in order to test spent brewer's yeast as a replacement for fishmeal in diets for giant freshwater prawn (Macrobrachium rosenbergii) reared in either a recirculating aquaculture system (RAS) or a biofloc system. Triplicate groups, each of 20 prawn (6.7 ± 0.03 g), were randomly assigned to 24 identical tanks. Twelve tanks were connected to the RAS, and the other 12 tanks were connected to the biofloc system which were initially supplemented with Bacillus subtilis, molasses and blood meal to achieve a C:N ratio of 20:1. Four iso‐nitrogenous (350 g/kg) and iso‐energetic (19 MJ/kg) diets where 0%, 20%, 40% and 60% of fishmeal protein was replaced by spent brewer's yeast. Neither growth nor survival was affected (p > 0.05) by increasing levels of brewer's yeast. The exception, being fish given 60% replacement with brewer's yeast, reared in biofloc, which displayed a higher (p < 0.05) growth than fish given 40% replacement, reared in clear water. The feed conversion ratio of prawn reared in the biofloc environment was lower than in the clear water. We concluded that spent brewer's yeast represents a possible 60% substitute for fishmeal in giant freshwater prawn diets, especially for prawn reared in a biofloc environment.     

Acclimation of <Emphasis Type="Italic">Anabas testudineus</Emphasis> (Bloch) to three test temperatures influences thermal tolerance and oxygen consumption

Teleost fish have developed their own specific adaptive mechanism, both behavioral and physiological, to maintain homeostasis in response to unfavorable temperatures. Therefore, this study was aimed at assessing the critical thermal maxima (CT_Max), critical thermal minima (CT_Min), and oxygen consumption rate of Anabas testudineus (17.03 ± 1.2 g) after acclimating to three preset temperatures (25, 30, and 35°C) for 30 days. The CT_Max and CT_Min were 40.15, 41.40, 41.88°C and 12.43, 13.06, 13.94°C, respectively, and were significantly different (P < 0.05). The thermal tolerance polygon for the specified temperatures was 278.30°C². The oxygen consumption rate (117.03, 125.70, 198.48 mg O₂ kg⁻¹ h⁻¹, respectively) increased significantly (P < 0.05) with increasing acclimation temperatures. The overall results indicate that the thermal tolerance and oxygen consumption of A. testudineus are dependent on acclimation.     

Physiological Analysis of Growth, Yield Development and Grain Quality of Some Deep-water Rice (Oryza sativa L.) Cultivars

A field experiment was conducted with 10 deep‐water rice varieties (nine traditional and one improved), viz. Amona, Maguri, Rangoli, Kakua, Panikakua, Deoribao, Moimonsingia, Duatkalam, Dalbao and PJNB‐96‐10, to study their physiological performance, grain‐quality characters and yield. Among the cultivars, significant variations were recorded in plant height, root length, number of internode, tiller number, number of ear‐bearing tillers, panicle length, panicle weight, number of spikelets per panicle and filled grain percentage. The highest number of spikelets per panicle (199), filled grain percentage (95 %) and grain yield (4.32 t ha^?1) were recorded in Maguribao. The highest grain length was recorded in PNJB‐96‐10 (9.5 mm), whereas highest grain thickness was observed in Duatkalam (2.8 mm). Glutelin was the most dominant fraction of protein in all the tested cultivars. Maguribao showed the highest glutelin content (26.7 mg g^?1 dry weight), whereas Panikakua showed the highest amylose (24.45 %) and crude fat (4.64 %) content. Differences were also recorded among cultivars in fibre, ash and iron content in grain. Maguribao was found to have superior physiological traits for growth and hence may be considered for inclusion in deep‐water rice breeding programmes.     

Microbial Phytase Supplementation in Rohu, Labeo rohita, Diets Enhances Growth Performance and Nutrient Digestibility

Abstract.— A feeding trial was conducted for 60 d to study the effect of dietary microbial phytase on growth performance and nutrient digestibility of rohu, Labeo rohita , fingerlings. One hundred and twenty fingerlings (average initial weight: 9.17 g/fish) were equally distributed into five experimental tanks, each with four replicates. Five isonitrogenous (35%) and isocaloric (16.79 kJ/g) diets were prepared from plant-based ingredients, supplemented with microbial phytase at the level of 0, 250, 500, 750, and 1000 U/kg diets and fed to T₀, T₁, T₂, T₃, and T₄ groups, respectively. Weight gain %, food conversion ratio, protein efficiency ratio, and apparent net protein utilization were significantly ( P  < 0.05) improved in groups fed phytase-supplemented diets compared to control, the highest being observed in T₃ group. Maximum apparent digestibility of phosphorus and crude protein was recorded in T₃ group. Bone ash, phosphorus (P), and calcium (Ca) contents were also significantly ( P  < 0.05) increased in phytase-fed groups. However, maximum was recorded in T₃ group. Results from the present study indicated that addition of 750 U microbial phytase/kg diets effectively improved nutrient utilization, bone mineralization, and hence growth of L. rohita fingerlings.     

Effect of mixed cation solutions on hydraulic soil properties

Hydraulic conductivity (K) and soil water diffusivity (D) characterizing water flow under saturated and unsaturated conditions, respectively, were determined for a sandy loam and a clay loam soil, using water with different combinations of total electrolyte concentrations, C (i.e., 20, 40, 80, 125 and 250 meq 1^?1) and sodium adsorption ratios, SAR (i.e., 0, 20, 30, 40, 80 and ∞ mmole $\text{l}{}^{\mathrm{<mtext>?</mtext><mtext>1</mtext><mtext>2</mtext>}}$). Both K and D were found to increase with C and decrease with SAR. In low sodium adsorption ratio ranges (i.e., up to 20) the requirement of electrolyte concentration to maintain relative hydraulic conductivity = 0.5 was relatively more for sandy loam than for clay loam soil. However, the trend for electrolyte concentration requirements for the two soils was reversed at high sodium adsorption ratios (i.e. > 20). A spline function was used to draw the best fitting line through the data points of horizontal absorption experiments.     

Identification of optimal level of nitrogen fertilizer and tillage practice to reduce nitrous oxide emissions and maximize the nitrogen use efficiency and productivity from tropical rice paddy

Paddy and Water Environment - Agricultural tillage practices and fertilizer play an important role in production and consumption of greenhouse gases (GHGs), which contribute to global climate...     

Water soaking and exogenous enzyme treatment of plant-based diets: effect on growth performance, whole-body composition, and digestive enzyme activities of rohu, Labeo rohita (Hamilton), fingerlings

A 2 × 2 × 2 factorial experiment was conducted to delineate the main effect of water soaking of plant ingredients, phytase, cellulase, and their interactions on the growth and digestive enzyme activities of Labeo rohita fingerlings. Two basal diets were prepared using water-soaked (S) or unsoaked (US) plant-based ingredients. Feed of US ingredients was supplemented with phytase (U kg⁻¹) and cellulase (%) at the level of 0, 0 (C_us); 500, 0 (T₁); 0, 0.2 (T₂); 500, 0.2 (T₃), and feed of S ingredients at 0, 0 (C_s); 500, 0 (T₄); 0, 0.2 (T₅), and 500, 0.2 (T₆), respectively. Three hundred and sixty fingerlings were randomly distributed into eight treatments, each with three replicates. Soaking of the ingredients for 24 h significantly reduced the tannin content. However, feeding of S diets did not improve the fish growth. Highest performance was recorded in the T₃ group. A significant interaction between dietary phytase and cellulase was observed for apparent net protein utilization. Tissue crude protein, ether extract, and ash content of the fingerlings were observed highest in the T₃ group. Activities of amylase, protease, and lipase were recorded highest in the T₃ group. Results suggested that soaking of plant-based ingredients reduces tannin content; however, growth and digestive enzyme activities of group fed soaked diet were not improved, possibly due to leaching of soluble nutrients. Probably, a shorter duration soaking may be effective in reducing tannin content and avoiding nutrients leaching.     

Effect of substituting live feed with formulated feed on the reproductive performance and fry survival of Siamese fighting fish, Betta splendens (Regan, 1910)

This study aimed to elucidate the effect of partial or complete replacement of live feed (LF) (Tubifex) with formulated feed (FF) on the reproductive performance of Betta splendens. Three hundred B. splendens fry (average weight 0.19 ± 0.01 g) were equally distributed into five different groups, each with three replicates. They were fed for 105 days with following different diets: control (C)—100% LF; T1—75% LF, 25% FF; T2—50% LF, 50% FF; T3—25% LF, 75% FF, and T4—100% FF. Results showed that the average number of hatched larvae (654 ± 101) and fry survival after 2 weeks of rearing (428 ± 70), after completion of three spawning, were recorded highest in the control group, which was, however, not significantly different from the T1, T2, and T3 groups. At the end of the feeding trial, the highest hatching percentage (90.3%) was registered in the T2 group, which was not significantly different from the control and T1 groups. The T2 group also recorded highest fry survival (65.54%) after completion of three spawning, which was not significantly (P < 0.05) different from the T1 and T3 groups. Control diet contained higher saturated fatty acid (63.23%) than formulated diet (29.80%). In the whole-body tissue, highest level of EPA (0.42%) and DHA (3.13%) were found in the T4 group followed by T3 group. The DHA/EPA ration was recorded highest in the T2 group (10.96%), which did not differ significantly from the T1 and T3 groups. Significant positive correlation was observed between saturated fatty acid levels in fish whole-body tissue and number of hatched larvae (Y = 30.81 × −825.3, R ² = 0.968) and fry survival after 2 weeks of rearing (Y = 21.38 × −580.9, R ² = 0.967). Considering all these factors, it can be concluded that the live feed Tubifex can be replaced up to 50% without any adverse effect on the reproductive performance and fry survival of B. splendens.     

Cold tolerance at the early growth stage in wild and cultivated rice

The present study was conducted to understand the pattern of variation and the genetic bases for cold tolerance at the early growth stage in Asian rice. The genetic variation was investigated at the germination, plumule and seedling stages among 57 strains including cultivated rice (Oryza sativa ssp. indica and ssp. japonica) and its wild progenitor (Oryza rufipogon). The significant differentiation of cold tolerance was observed among the taxonomically divided groups. At the germination stage, both indica and japonica subspecies tended to be more tolerant than O. rufipogon, whereas at the plumule and seedling stages, ssp. japonica tended to be more tolerant than ssp. indica and O. rufipogon. Furthermore, in cold tolerance at the plumule stage, the clinal variation across the latitude of origins was observed within O. rufipogon and ssp. japonica, suggesting that the current pattern of variation seems to have been shaped by both their phylogenetic histories and on-going adaptation to the local environments. QTL analysis between O. sativa ssp. japonica (tolerant) and O. rufipogon (susceptible) revealed five putative QTLs for cold tolerance at the plumule and seedling stages but not at the germination stage. Substitution mapping was also carried out to precisely locate the two major QTLs for cold tolerance at the plumule stage, which could be used for improvement of tolerance to cold stress in ssp. indica.