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Abstract.— Quantitative changes in the protein, lipid and carbohydrate were studied in the early larval stages of developing freshwater prawn Macrobrachium rosenbergii reared under fed and starved conditions to understand the relative importance of these nutrients in energy metabolism of the growing larvae. Larvae obtained from several females were stocked into three 250-L tanks at a density of 30 larvae/L. The feeding regime consisted of newly hatched Artemia nauplii. Protein was always the major organic constituent followed by lipids and then carbohydrates of both fed and starved larvae. Protein levels of both fed and starved larvae increased during development, suggesting an important role in morphogenesis. The decline of lipid during the larval growth that was more rapid for starved larvae, suggests a probable utilization of lipid as the major metabolic source of energy. Carbohydrates formed less than 5 and 2.4% of the larval dry weight of fed and starved larvae, respectively, suggesting their limited role in larval metabolism.  相似文献   
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In this work, the effect of organosolv lignin on properties of polypropylene (PP)/chitosan composites was investigated. Mechanical and thermal properties of the composites were analyzed by means of ASTM D 638-91, ASTM D 256, thermogravimetry analysis (TGA) and differential scanning calorimetry (DSC). Tensile strength and elongation at break of the PP composites decreased upon the presence of chitosan filler, but Young’s modulus improved. Impact strength was found to increase with the maximum value at 30 php of filler loading. At a similar loading, treated PP/chitosan composites were found to have higher tensile strength, elongation at break, Young’s modulus as well as impact strength than untreated composites. Furthermore, the presence of organosolv lignin imparted a plasticizing effect. Thermal properties of the treated PP/chitosan composites were better as compared with the untreated PP/chitosan composites; although the chemical treatment did not alter the thermal degradation mechanism. In addition, the obtained results were comparable to results from previous studies. This finding implied that the organosolv lignin could be a potential reagent to replace its synthetic counterpart.  相似文献   
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This study was conducted to determine the biological filtration capabilities of some culinary herbs co‐cultured with lemon fin barb hybrid in a nutrient film technique (NFT) recirculating aquaponic system. Lemon fin barb hybrid (Hypsibarbus wetmorei ♂ × Barbonymus gonionotus ♀) fingerlings were stocked in twelve 2‐tonne fibreglass tanks at 25 fish per tank and co‐cultured with Chinese celery (Apium graveolens var. secalinum Alef.), coriander (Coriandrum sativum) and peppermint (Mentha × piperita) for seven weeks. The impacts of the waste generated by the fish on the water quality, the filtration capability of the herbs and the ability of fish and herbs to retain nutrients (NPK) were also estimated. All the herbs showed water purifying potentials to varying degrees as significantly lower levels of nitrogenous compounds (NH3‐N, NO3‐N, NO2‐N) were observed after the herbal filtration. The plant growth seemed to be affected by their ability to absorb nutrients and consequently purify the culture medium. Interestingly, the lemon fin barb hybrid also showed significant differences in terms of weight gain, but the nutrient retention among fish treatments was not statistically different. The plants absorbed less phosphorus and potassium than the fish. After computing for the total system percentage of NPK recovered, nitrogen was the most retained nutrient. The peppermint showed superiority in terms of gross biomass and water purifying potential compared to the Chinese celery and coriander.  相似文献   
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The performance of selected leaf meals of high dietary fibre in the feed of a tropical commercial carp, hybrid lemon fin barb (Barbonymus gonionotus ♀ × Hypsibarbus wetmorei ♂) was evaluated in a 56‐day feeding trial. The tropical carp juveniles (9.43 ± 0.05 g) were randomly stocked in 60‐L aquaria at 15 fish per aquarium. Five isonitrogenous and isocaloric diets (30% crude protein, 17 kJ/g gross energy) containing no leaf meal and 10% napier grass (Pennisetum purpureum), alfalfa (Medicago sativa), water spinach (Ipomea aquatica) and Gliricidia sepium leaf meals were formulated and tested. Three aquaria were randomly assigned to each experimental diet. The results showed that fish‐fed diets containing leaf meals showed superior growth performance and body composition which was better than those fed control diet. The leaf meal‐treated groups also had higher values of protein, lipid, energy retention and production of digestive enzymes amylase. Conclusively, the results indicated that leaf meal fibre provided better performance showing the inherent prebiotic effect of the utilization of these leaf meal in hybrid lemon fin barb .  相似文献   
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Most research works on the production frontier in aquaculture focus on efficiency measurement using either Stochastic Production Frontier (SPF) or Data Envelopment Analysis (DEA). The studies on productivity growth in aquaculture were limited, perhaps due to lack of time-series data. Nevertheless, total factor productivity analysis (TFP) in fish farms has started gaining popularity in recent years. In addition, the majority of the efficiency studies have centered on technical efficiency analysis but substantial increases in the output levels can be fully realized through improving overall economic efficiency. Therefore, this review suggests that future research should estimate all three efficiency indices (i.e., technical, allocative and economic efficiencies).  相似文献   
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Abstract

Nodule formation in legume crops is a multistep process which involves the interactive gene expression of bacteria and host plants. Attempts to widen the genetic variation of symbiotic bacteria and host plants have led to the isolation of several mutants with a diverse capability of nodulation. The most striking variants in hosts are the supernodulating mutants isolated in pea (Pisum sativum L.) (Jacobsen and Feenstra 1984; Duc and Messager 1989), common bean (Phaseolus vulgaris L.) (Park and Buttery 1988), and soybean (Glycine max (L.) Men.) (Carroll et al. 1985a,b; Gremaud and Harper 1989; Akao and Kouchi 1992), all of which are capable of producing several-fold more nodules than their parental lines in the presence of nitrate. These mutants may be useful materials for analyzing the mechanism controlling nodule formation, and are considered to have a high agronomic potential under certain growing conditions.  相似文献   
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Abstract.— Amino acid profiles of freshwater prawn Macrobrachium rosenbergii were determined during early larval stages (I-IX) to provide some baseline biochemical information of the growing larvae. The larvae obtained from several females were stocked into three 250-L tanks at a density of 30 larvae/L. The feeding regime consisted of newly hatched Artemia nauplii and egg custard containing 5% cod liver oil. For each developmental stage, larval samples from each experimental tank were pooled, freeze dried and after acid hydrolysis, the quantification of amino acids was done by a reverse phase high performance liquid chromatography ( N = 2). The highest represented of the total amino acids were for glutamic acid and phenylalanine (with cystine) with ranges from 13.4–16.6 and 9.7–11.5%, respectively, whereas tryptophan (1.4–1.6%). methionine (1.4–2.7%) and histidine (2.9–4.2%) were relatively lower. The levels of the following essential amino acids did not significantly change during larval development: arginine, leucine, phenylalanine (plus cystine), threonine, tryptophan and valine. Despite statistically significant changes that were observed in levels of some amino acids, amino acid composition appeared to be relatively unchanged during the larval growth. The results may suggest that the amino acid requirements of the freshwater prawn is relatively constant during larval life and can be satistied by a suitable protein source that resembles the larval amino acid profile.  相似文献   
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The optimum dietary protein requirement of the Malaysian mahseer (Tor tambroides) fingerlings was determined in this study. In this completely randomized designed experiment, formulated diets of five levels of dietary protein (30, 35, 40, 45 and 50%) were tested on the T. tambroides fingerlings (initial body weight of 5.85 +/- 0.40 g), reared in aquarium fitted with a biofiltering system. The fingerlings were fed twice daily at 5% of biomass. The fingerling body weight and total length was taken at every two weeks. Mortality was recorded daily. The dietary protein had significant effects on the body weight gain and Specific Growth Rate (SGR) of the fingerlings. The body weight gain and SGR of fingerlings fed with the diet with the dietary protein level of 40% was significantly higher (p<0.05) than that of 30, 35 and 50%. The feed conversion ratio of the 40% dietary protein was the significantly lowest at 2.19 +/- 0.163. The dietary protein level of 40% was the most optimum for T. tambroides fingerlings.  相似文献   
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