Variability in the composition of lupin (Lupinus angustifolius) meals influences their digestible nutrient and energy value when fed to rainbow trout (Oncorhynchus mykiss)     

Brett Glencross  Wayne Hawkins  David Evans  Neil Rutherford  Peter McCafferty  Ken Dods  Max Karopoulos  Chris Veitch  Sofie Sipsas  Bevan Buirchell   《Aquaculture (Amsterdam, Netherlands)》2008,277(3-4):220-230

Over a series of seven separate experiments 76 different lupin (Lupinus angustifolius) meals were assessed for their digestible dry matter, protein, amino acid and energy characteristics when fed to rainbow trout. Two reference diets (a common basal diet and a reference lupin meal) were also included in each experiment. Minimal variance in the digestibility parameters of both reference diets was observed among the experiments ensuring that there was a high degree of robustness in the across-experiment evaluations. Using simple and multiple-regression techniques, principal diet and ingredient composition factors affecting diet and ingredient digestibilities and ingredient digestible values were explored within the dataset. Using simple linear regression, it was shown that nitrogen digestibility of the lupin meals was negatively influenced by ingredient lignin content, but positively affected ingredient protein (N × 6.25) content. The energy digestibility of the lupin meals was positively affected by a range of compositional features including protein, sum of amino acids and negatively affected by carbohydrate content. The digestible nutrient and energy content of the meals reflected the combined effects of both ingredient digestibilities and ingredient composition. The digestible nitrogen content of the lupin meals was positively affected by protein (N × 6.25), sum of amino acids and energy content, but was negatively affected by lignin and carbohydrate content. The digestible sum of amino acids was also positively affected by protein, sum of amino acids, but only negatively affected by carbohydrate content, not lignin content. The digestible energy content of the lupin meals was also positively affected by protein, sum of amino acids and their own energy density, but only negatively affected by carbohydrate content. Multiple linear regression modelling supported that together ingredient protein and lignin content were the strongest predictors of digestible protein value, explaining close to 60% of the variability in this parameter. Discrete reassessment of these relationships using non-linear analysis methods provided a stronger interpretation of the ingredient composition effects. In recognition of this, a functional model including terms for ingredient protein and lignin content on the digestible protein value was defined. This study demonstrates that within one raw material type that not only does significant variability in the digestible value of the raw materials exist, but that it is possible to identify compositional features of that raw material that are intrinsically influencing their own digestible value.  相似文献   

Large-scale experiment shows that nylon leaders reduce shark bycatch and benefit pelagic longline fishers   总被引：1，自引：0，他引：1  

Peter Ward  Emma Lawrence  Rebecca Darbyshire  Sheree Hindmarsh 《Fisheries Research》2008,90(1-3):100-108

We assess the performance of wire leaders, which some jurisdictions have banned to reduce shark mortality from pelagic longline fishing. Experiments were conducted off northeastern Australia on commercial vessels that deployed equal numbers of wire and nylon monofilament leaders randomly along their longlines. Catch rates of several species, including sharks, were lower on nylon than on wire leaders, probably because those animals often escape by biting through the nylon leaders. High bite-off rates indicate that as many animals escape from nylon leaders as are caught on nylon leaders. The fate of escaped animals is not known, although large sharks are more likely to survive than are small animals. By contrast, catch rates of valuable bigeye tuna (Thunnus obesus) were higher on nylon than on wire leaders. Bigeye tuna are probably able to see wire leaders and avoid those hooks. The financial benefits of increased bigeye tuna catches outweigh the costs associated with banning wire leaders, such as increased rates of gear loss. Thus, banning wire leaders is an effective way of reducing shark catches that fishers should be keen to adopt.  相似文献   

Effects of Atrazine Drift on Production Pond Plankton Communities and Water Quality Using Experimental Mesocosms     

Peter W.  Perschbacher Gerald M.  Ludwig Regina  Edziyie 《Journal of the World Aquaculture Society》2008,39(1):126-130

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pH对鱼类化学感觉的影响   总被引：11，自引：0，他引：11       下载免费PDF全文

周洪琪  彼得·约翰逊 《水产学报》1988,12(2):169-172

关于硬骨鱼类的嗅、味感觉器官在解剖学和生理学方面的研究成果，许多学者都发表过综述文章(Kleerekoper1969，Bardach和Atema1971，Bardach和Villars1974，Kapoor等1975，Brown和Hara1982，Tucker1983)，最近十几年，对于鱼类化学感觉的电生理研究，主要在于一些天然物质、氨基酸及其衍生物对于嗅、味觉系统的相对刺激效果，刺激物的分子结构与刺激效果的关系，以及刺激物与感受细胞膜上的感受点相互作用的机制，而对于人为因素如捕捞、环境因素pH、污染对鱼类嗅、味觉的影响报导甚少(Hara1976，1978，Konishi等1969，Tucker1973，Silver，1978，Cancolon1980，Hidaka1970)。鱼类的嗅、味觉在鱼类生命活动如摄食、洄游、生殖、逃避敌害、群体的控制等等行为中起重要的作用，当人们利用鱼类嗅、味觉的一些生理活动规律为生产实践服务时，pH是不可忽视的一个因素，本试验以重要的生物信息分子氨基酸为刺激物，研究pH对于鱼类嗅、味觉系统对氨基酸敏感性的影响。  相似文献   

Fertilizer ammonium : nitrate ratios determine phosphorus uptake by young maize plants     

Ingeborg F. Pedersen  Peter Srensen  Jim Rasmussen  Paul J. A. Withers  Gitte Holton Rubk 《植物养料与土壤学杂志》2019,182(4):541-551

We investigated the interacting effects of inorganic nitrogen and the main inorganic phosphorus form in dairy manure (dicalcium phosphate, CaHPO₄) on growth, nutrient uptake, and rhizosphere pH of young maize plants. In a pot experiment, three levels of CaHPO₄ (0, 167, and 500 mg P pot^?1) were combined with nitrogen (637 mg N pot^?1) applied at five NH₄‐N : NO₃‐N ratios (0 : 100, 25 : 75, 50 : 50, 75 : 25, and 100 : 0) and a nitrification inhibitor in a concentrated layer of a typical acid sandy soil from Denmark. ¹⁵N‐labeled NH₄‐N was applied to differentiate the role of nitrification and to partition nitrogen uptake derived from NH₄‐N. Among treatments including nitrogen, shoot biomass, rooting and phosphorus uptake were significantly higher at the five‐leaf stage when CaHPO₄ was applied with NH₄‐N : NO₃‐N ratios of 50 : 50 and 75 : 25. In these treatments, rhizosphere pH dropped significantly in direct proportion with NH₄‐N uptake. The fertilizers in the concentrated layer had a root‐inhibiting effect in treatments without phosphorus supply and in treatments with pure NO₃‐N or NH₄‐N supply. Increased nitrogen uptake as NH₄‐N instead of NO₃‐N reduced rhizosphere pH and enhanced acquisition of applied CaHPO₄ by young maize plants, which may have positive implications for the enhanced utilization of manure phosphorus.  相似文献   

Microbial remediation of a pentachloronitrobenzene-contaminated soil under Panax notoginseng: A field experiment     

Ning ZHANG  Dong GUO  Ye ZHU  Xiaomi WANG  Lingjia ZHU  Fang LIU  Ying TENG  Peter CHRISTIE  Zhengao LI  Yongming LUO 《土壤圈》2020,30(4):563-569

Pentachloronitrobenzene (PCNB) is an organochlorine fungicide that is mainly used in the prevention and control of diseases in crop seedlings. Microbial removal is used as a promising method for in-situ removal of many organic pesticides and pesticide residues. A short-term field experiment (1 year) was conducted to explore the potential role of a PCNB-degrading bacterial isolate, Cupriavidus sp. YNS-85, in the remediation of a PCNB-contaminated soil on which Panax notoginseng was grown. The following three treatments were used:i) control soil amended with wheat bran but without YNS-85, ii) soil with 0.15 kg m^-2 of solid bacterial inoculum (A), and iii) soil with 0.30 kg m^-2 of solid bacterial inoculum (B). The removal of soil PCNB during the microbial remediation was monitored using gas chromatography. Soil catalase and fluorescein diacetate (FDA) esterase activities were determined using spectrophotometry. In addition, cultivable bacteria, fungi, and actinomycetes were counted by plating serial dilutions, and the microbial biodiversity of the soil was analyzed using BIOLOG. After 1 year of in-situ remediation, the soil PCNB concentrations decreased significantly by 50.3% and 74.2% in treatments A and B, respectively, when compared with the uninoculated control. The soil catalase activity decreased in the presence of the bacterial isolate, the FDA esterase activity decreased in treatment A, but increased in treatment B. No significant changes in plant biomass, diversity of the soil microbial community, or physicochemical properties of the soil were observed between the control and inoculated groups (P<0.05). The results indicate that Cupriavidus sp. YNS-85 is a potential candidate for the remediation of PCNB-contaminated soils under P. notoginseng.  相似文献   

Reciprocal transfer effects on denitrifying community composition and activity at forest and meadow sites in the Cascade Mountains of Oregon     

Stephanie A. Boyle  Peter J. Bottomley  Kermit Cromack Jr. 《Soil biology & biochemistry》2006,38(5):870-878

In order to examine the effects of disturbance, vegetation type, and microclimate on denitrification and denitrifier community composition, experimental plots were established at the H. J. Andrews Experimental Forest in the Cascade Mountains of Oregon. Soil cores were reciprocally transplanted between meadow and forest and samples were collected after 1 and 2 years. Denitrifying enzyme activity (DEA) was measured using the acetylene block assay and terminal restriction length polymorphism profiles were generated with nosZ primers that target the gene coding for nitrous oxide reductase. Nitrate concentrations, C mineralization, and water content were measured to gain additional insights into soil properties controlling DEA. Meadow soils were significantly higher in DEA than forest soils, and the highest DEA levels were observed in cores transferred from the meadow into the forest. Nitrate concentrations were also different between forest and meadow soils, but did not correlate to DEA. DEA was higher in open versus closed cores, suggesting an association between denitrification and the rhizosphere. Denitrifier communities of undisturbed forest and meadow soils shifted through a 4-year period but remained distinct from each other. Similarly, denitrifier communities clustered by vegetation type of origin regardless of manipulation, suggesting that the overall denitrifier communities are well buffered against environmental changes.  相似文献   

Substrate utilization by Aspergillus flavus in inoculated whole corn kernels and isolated tissues     

Mellon JE  Dowd MK  Cotty PJ 《Journal of agricultural and food chemistry》2005,53(6):2351-2357

Utilization of the major corn (Zea mays) reserve materials (free saccharides, starch, triglycerides, and zein) was monitored during infection of detached kernels by Aspergillus flavus (A. flavus) over a 12-day period. Inoculated whole kernels were compared to noninoculated kernels. Concentrations of sucrose and raffinose in inoculated seed decreased to nearly zero at 6 days, whereas concentrations of these saccharides in noninoculated seed dropped at a considerably slower rate, and significant levels remained at the end of the incubation period. Triglyceride concentrations remained unchanged in the noninoculated seed but dropped continuously after 2 days in the inoculated seed. Starch and zein concentrations did not change during the 12-day incubation period. Aflatoxin B1 was first detected after 2 days and increased to about 20 microg/g (20,000 ppb) after 12 days. Very low aflatoxin concentrations were detected in the noninoculated seed. Significant concentrations of erythritol, arabitol, and mannitol were produced during infection, with peak concentrations occurring at 8 days. Whole seed and germ tissue appeared to support good fungal growth and aflatoxin production, whereas ground tissues and endosperm did not. A. flavus preferentially utilized saccharides as initial carbon substrates followed by triglycerides. When invading nonwounded corn kernels, the fungus selectively targets the germ tissue where these materials are localized in the highest concentrations.  相似文献   

Influence of mycotoxin producing fungi (Fusarium, Aspergillus, Penicillium) on gluten proteins during suboptimal storage of wheat after harvest and competitive interactions between field and storage fungi     

Prange A  Modrow H  Hormes J  Krämer J  Köhler P 《Journal of agricultural and food chemistry》2005,53(17):6930-6938

Cereals contaminated by Aspergillus spp., Penicillium spp., and Fusarium spp. and their mycotoxins, for example, ochratoxin A (OTA) and deoxynivalenol (DON), are not only a risk to human and animal health but can also show poor technological properties and baking quality. The influence of these genera on the sulfur speciation of low molecular weight (LMW) subunits of glutenin was characterized by investigating suboptimally stored wheat samples in situ by X-ray absorption near edge structure (XANES) spectroscopy and baking tests. Field fungi of the genus Fusarium have hardly any influence on both the sulfur speciation of wheat gluten proteins and the baking properties, whereas storage fungi of the genera Aspergillus and Penicillium have a direct influence. An increased amount of sulfur in sulfonic acid state was found, which is not available for thiol/disulfide exchange reactions in the gluten network, and thus leads to a considerably reduced baking volume. From changes of the composition of the mould flora during suboptimal storage of wheat and from the mycotoxin contents, it can be concluded that microbial competitive interactions play an important role in the development of the mould flora and the mycotoxin concentrations during (suboptimal) storage of wheat.  相似文献   

基于电磁阀的喷嘴直接注入式农药喷洒系统   总被引：2，自引：0，他引：2  

蔡祥  Walgenbach Martin  Doerpmund Malte  Schulze Lammers Peter  孙宇瑞 《农业机械学报》2013,44(6):69-72,200

设计了一种喷嘴直接注入式农药喷洒系统。通过与传统喷雾机械比较,简述了喷嘴直接注入式喷雾系统的结构和喷雾执行单元。为了实现农药定量注入,设计一种基于电磁原理的快速响应阀,并论述其工作原理和闭环控制方式。通过试验测试了喷雾执行单元的喷雾特性和喷杆组内各喷雾单元的一致性。结果表明在一定喷洒速率范围内,喷雾执行单元的喷水量和水压强存在多项式关系,农药注入量和PWM信号的高电平时间存在指数关系,其决定系数均高于0.9,并且同一喷杆组内6个喷雾单元的喷雾效果大体一致。  相似文献