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21.
The effects of galactooligosaccharide (GOS) and a combination of yeast and β-glucan (YβG) supplementation of dietary soybean meal (SBM) on the growth and digestive performance of striped catfish Pangasianodon hypophthalmus were evaluated. Four isonitrogenous (30% protein) and isocaloric (19 MJ/kg diet) diets were formulated to contain 100% fish meal (FM) protein, 55% FM protein/45% SBM protein, FM-SBM supplemented with 1% GOS, and a combination of 1% yeast and 0.1% β-glucan, respectively. Each diet was fed for 12 weeks to three groups of 30 striped catfish fingerlings (average weight 16.45?±?0.07 g) maintained in circular fiberglass tanks (600 l). Growth, feed utilization, and muscle protein composition of fish improved significantly after supplementation with either GOS or YβG compared to the unsupplemented SBM diet, but were similar to those of fish fed the FM diet. Nutrient digestibility, digestive enzyme activities, villi and microvilli length were significantly increased in fish fed the supplemented SBM diets. The gut microbiota ranking profile showed that supplementing the SBM diet with YβG and GOS gave a ranking of Verrucomicrobia, Spirochaetes, Bacteriodetes, and Actinobacteria phyla similar to that of the FM diet. Thus, diet containing 45% protein from soybean supplemented with either GOS or YβG can be recommended to improve the growth and digestive performance of striped catfish.  相似文献   
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23.
The influence of dietary supplementation of Lactobacillus acidophilus, on growth performance, digestive enzyme activities, gut histomorphology and gut microflora were evaluated in juveniles striped catfish (Pangasianodon hypophthalmus). Five experimental diets were formulated by supplementing 0, 103, 105, 107 and 109 CFU/g L. acidophilus in fishmeal and casein‐based semi‐purified diet. Triplicate groups of striped catfish (21.69 ± 0.18 g) were stocked in 15 fiberglass tanks with stocking density of 25 individuals per tank and fed twice daily at 2.5% of the fish body weight for 12 weeks. Weight gain, specific growth rate, feed conversion ratio and the protein efficiency ratio were significantly higher in fish fed with 105 and 107CFU/g L. acidophilussupplemented diets compared with the other treatment groups. Compared with the control and fish fed low (103 CFU/g) L. acidophilus supplementation, those fed with 105 and 107 CFU/g had significantly higher (p < 0.05) apparent protein digestibility. Inclusion of L. acidophilus at 107 CFU/g diet significantly increased amylase, protease and lipase activities. Microscopic analysis showed that the villi length in both the anterior and posterior gut and microvilli length in the posterior gut increased significantly in fish fed L. acidophilus supplementation at 105 and 107 CFU/g of diet. The fish fed L. acidophilus supplemented diets significantly increased the total lactic acid bacteria counts in the gut of striped catfish compared with the control‐fed group. Based on gut histomorphology and growth performance, inclusion of L. acidophilus at 105 CFU/g appears to have the most positive effect on striped catfish farming.  相似文献   
24.
We mapped the forest cover of Khadimnagar National Park (KNP) of Sylhet Forest Division and estimated forest change over a period of 22 years (1988-2010) using Landsat TM images and other GIS data. Supervised classification and Normalized Difference Vegetation Index (NDVI) image classification approaches were applied to the images to produce three cover classes, viz. dense forest, medium dense forest, and bare land. The change map was produced by differencing classified imageries of 1988 and 2010 as before image and after image, respectively, in ERDAS IMAGINE. Error matrix and kappa statistics were used to assess the accuracy of the produced maps. Overall map accuracies resulting from supervised classification of 1988 and 2010 imageries were 84.6% (Kappa 0.75) and 87.5% (Kappa 0.80), respec- tively. Forest cover statistics resulting from supervised classification showed that dense forest and bare land declined from 526 ha (67%) to 417 ha (59%) and 105 ha (13%) to 8 ha (1%), respectively, whereas medium dense forest increased from 155 ha (20%) to 317 ha (40%). Forest cover change statistics derived from NDVI classification showed that dense forest declined from 525 ha (67%) to 421 ha (54%) while medium dense forest increased from 253 ha (32%) to 356 ha (45%). Both supervised and NDVI classification approaches showed similar trends of forest change, i.e. decrease of dense forest and increase of medium dense forest, which indicates dense forest has been converted to medium dense forest. Area of bare land was unchanged. Illicit felling, encroachment, and settlement near forests caused the dense forest decline while short and long rotation plantations raised in various years caused the increase in area of medium dense forest. Protective measures should be undertaken to check further degradation of forest at KNP.  相似文献   
25.
Effect of Fine Root Contact on Plant-Induced Weathering of Basalt   总被引:1,自引:0,他引:1  
The objective of the present study was to provide experimental evidence on the active role of plant roots in rock weathering and the importance of the proximity of roots to rock in the weathering process. The analysis was based on the release of different elements from basalt rock particles by three crop species: rice, soybean and maize. Quantitative results were obtained by chemical analyses. We designed two types of hydroponic crop pots, in which fine roots were allowed (or not allowed) to make contact with rock particles by using coarse (or fine) net bags. Experiments were carried out in a controlled glasshouse during a 42 d period. The release of elements in the presence of the plants was calculated by subtracting the decrease in the amounts of elements in the media from the amounts absorbed by the plants. We observed the positive effect of plants on the release of elements from the rock particles and the highest amounts were released in the soybean pots. The amounts of Si, Ca, Mg, Mn and Al released increased by a factor of 2–5, 2–7, 16–112, 3–19 and 6–60, respectively. The amount of Fe released by soybean plants from the rock particles was 4–6 times higher than that by other plants. Between the coarse and fine net pots, the amount of released elements differed significantly only for soybean (Si, Mg and Mn at p < 0.01 level and Fe at p < 0.05 level), which displayed the most vigorous growth. Our results imply that weathering may be caused partially by the absorption of nutrient elements directly through the interface of fine roots and rock particles, and is most likely associated with alterations of the local rhizosphere conditions surrounding the roots.  相似文献   
26.
Lack of proper nutrition is one of the most serious problem across the globe, affecting majorly African countries, where many children died not only due to inadequate food but also as a result of insufficient nutrient in their diet. This research was aimed to study the proximate composition and screening of chemical components in different part of Moringa oleifera Lam. Proximate analysis was adapted from the standard methods developed by Association of Official Analytical Chemists (AOAC). We have determined percentage of moisture content, ash content, crude protein, crude fibre, crude fat and carbohydrate which were ranges from 8.1–4%, 5.59–9.28%, 11.70–26.57%, 21.03–44.27, 11.82–20.19 and 8.16–31.12% respectively. Different bioactive compounds of polyphenol, flavonoids, tannins and saponin were determined. Different parts of plants accumulate different levels of polyphenol, flavonoids, tannins and saponin. Our study suggest that Moringa oleifera can served as a good supplement to our nutrition, due to high content of fibre, protein, fat. However intake of Moringa plant might reduce the risk of many oxidative related problems due to the present of some polyphenols and flavonoid in almost all part of the plant used.  相似文献   
27.
Background : The soils under continuous rice monocropping are currently facing a serious threat of accelerated soil and environmental quality degradation. Aims : Examining the impact of tillage and cropping diversity on soil aggregate stability and associated nutrients in a sub‐tropical rice ecosystem. Methods : A split‐plot experiment with tillage (minimum, MT vs. conventional, CT) as a main plot and cropping diversity [mustard (Brassica napus)–rice (Oryza sativa)–rice (M–R–R), wheat (Triticum aestivum)–rice–rice (W–R–R), and lentil (Lens esculenta)–rice–rice (L–R–R)] as a sub‐plot was repeated for four years. Soil aggregate properties were measured using wet sieving techniques. Soil organic carbon (SOC) and nutrients were measured in different aggregate size groups as well as in the bulk soil samples. Results : Results show that all the aggregate size groups were similar in both MT and CT, except in 0.85–0.30 mm. Likewise, cropping diversities increased soil aggregation, being higher aggregate size of < 0.053 mm in M–R–R relative to the W–R–R and L–R–R, where the latter two were alike. By contrast, > 2 mm aggregates were higher in L–R–R than in M–R–R and W–R–R, where the latter two were similar. The MT increased aggregate mean weight diameter (MWD) by 14% in W–R–R, and by 29% in L–R–R. Soil organic carbon (SOC), total N (TN), and available P were higher in MT than in CT, while it was alike for exchangeable K and available S. While W–R–R had a higher aggregate‐associated SOC, available P, and available S, L–R–R had a higher TN, and M–R–R had a higher exchangeable K. While SOC, TN, and exchangeable K accumulated more in the > 0.85 mm size aggregates, the available P, in contrast, accumulated more in < 0.85 mm size aggregates. Conclusion : Wheat–rice–rice diversity, coupled with minimum tillage, has a higher potential for soil fertility sustenance and crop productivity through better nutrient protection.  相似文献   
28.
Biodegradable packaging is gaining much attention in food industry as the awareness on sustainability has increased. Thermoplastic starch is a possible alternative. This study evaluated the influence of malic acid (MA) and citric acid (CA), used as a plasticizer, on the mechanical properties of thermoplastic starch (TPS) obtained by spray drying. TPS powder was produced from solution spray drying. This powder was further compression molded to prepare TPS dog-bone test samples. X-ray Diffraction (XRD) results showed that both the spray dried TPS powder and dog-bone test samples were amorphous in nature irrespective of the amount of plasticizer added. Scanning electron microscope (SEM) was used to examine the morphology of solution spray dried TPS powder. No noticeable difference was observed in the morphology. Particles were spherical in shape with homogenous surface. The FT-IR analysis indicated the interaction of plasticizers with starch chains by hydrogen bonding. During TGA analysis, apart from moisture loss at 100 °C, samples were thermally stable up to 170 °C. Mechanical testing of TPS dog-bone revealed that sample containing malic acid as plasticizer exhibited a more elastic behavior as compared to citric acid plasticized formulations. It was revealed that the tensile strength of TPS dog-bone samples was inversely proportional to the quantity of plasticizer used.  相似文献   
29.
The effect of hot-water and alkaline pre-extraction of rice straw on soda-anthraquinone pulping was carried out. The pre-extraction with hot water at 150 °C for 1 h dissolved 34.7% biomass and the pre-extracted liquor comprised of 16.6% sugars, 6.7% lignin, 6.6% acetic acid and other unknown products. But the pre-extraction with 1% NaOH at 100 °C for 1 h dissolved 10.2% sugars, 5.1% lignin and 10% acetic acid from rice straw. Pre-extracted rice straw was cooked by soda-anthraquinone process with varying alkali charges. The pulp from pre-extracted rice straw was low in kappa number with reduced pulp yield. The drainage resistance (°SR) improved obviously on pre-extraction of rice straw. Pulp strength properties such as the tensile index and the burst index were found to be lower, but the tear index was higher both with hot-water and alkaline pre-extraction. After bleaching, the gaps of the overall pulp yield and strength properties between pre-extracted and non-extracted rice straw became narrower. The alkaline pre-extraction showed improved yield and properties compared with hot-water pre-extracted rice straw.  相似文献   
30.
The rice panicle architecture depends on the arrangement of branches and spikelets which directly affect grain yield. We identified a mutant for panicle apical abortion (PAA-Hwa) from a japonica cultivar Hwacheongbyeo treated with N-methyl-N-nitrosourea. Under normal growth conditions, the mutant had multiple abnormal phenotypes, such as a slight reduction in plant height, narrow and dark green leaf blades, and small erect panicles with clear PAA compared to the wild-type plants. Genetic analysis revealed that the PAA was controlled by a single recessive gene, which is tentatively designated as paa-h. The paa-h gene was fine mapped at an interval of 71 kb flanked by sequence tagged site markers aptn3 and S6685-1 at the long arm of chromosome 4. Sequence analysis of the candidate genes within the delimited region showed a single base-pair change corresponding to an amino acid substitution from glycine to glutamic acid at the candidate gene, LOC_Os04g56160. We expect that the paa-h gene will be a clue to uncover the molecular mechanism of PAA and to maintain the panicle identity for grain yield in rice breeding programs.  相似文献   
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