Palm oil-laden spent bleaching clay as a substitute for marine fish oil in the diets of Nile tilapia, Oreochromis niloticus     

W.-K. NG  C.-B. KOH  & Z.B. DIN 《Aquaculture Nutrition》2006,12(6):459-468

A 8‐week feeding trial was conducted to determine the effect of substituting fish oil with palm oil‐laden spent bleaching clay (SBC), a by‐product from crude palm oil (CPO) refining, on growth, feed utilization, fatty acid composition and heavy metal accumulation in the muscle of Nile tilapia, Oreochromis niloticus. Four isonitrogenous and isolipidic practical diets were formulated to contain 0, 100, 200 or 300 g kg^?1 SBC. Growth performance of Nile tilapia was significantly better in fish fed the 100 g kg^?1 SBC diet compared with fish fed the 0, 200 or 300 g kg^?1 SBC diet. Growth and feed utilization efficiency of fish fed 200 or 300 g kg^?1 SBC were similar to fish fed the control diet without added SBC. Whole‐body composition, body‐organ indices and haematocrit of tilapia were not affected by dietary treatments. Fatty acid compositions in the muscle lipid of Nile tilapia were strongly influenced by dietary treatments with progressively elevated levels of total saturates and n‐6 PUFA because of the dietary influence of these fatty acids from residual CPO adsorbed onto SBC. A gradual decrease in total n‐3 PUFA concentrations were also observed with the ratio of n‐3 to n‐6 fatty acids in muscle lipids decreasing from 4.75 to 4.41, 3.23 or 2.37 after 8 weeks on the 0, 100, 200 or 300 g kg^?1 SBC diet, respectively. The arsenic, cadmium and lead concentrations in the experimental diets increased with increasing dietary levels of SBC but the concentrations of these heavy metals in the whole body and bone of Nile tilapia were not significantly different among fish fed the various diets. The present 8‐week study showed that in fishmeal‐based diets for Nile tilapia, palm oil‐laden SBC can totally replace added fish oil. The use of this presently discarded waste product from palm oil refining in tilapia diets will greatly contribute to reducing the impact of rising feed costs in the culture of tilapia in many tropical countries. Other potential benefits may include acting as a feed binder, removal of mycotoxins in fish feeds as well as adsorbing toxic substances present in the culture water.  相似文献   

The use of hand-held terminals and micro-computers for the recording and analysis of potato cyst nematode counts     

Linda Farrer  C. M. NG Stephen 《Euphytica》1982,31(2):507-510

Summary An automated system of data capture and summarisation is described. Although it is of widespread applicability, it is illustrated by a specific example involving the screening of potato tubers for resistance to potato cyst nematode.  相似文献   

实时实地氮肥管理对水稻产量和氮素利用率的影响   总被引：117，自引：12，他引：117  

刘立军  桑大志  刘翠莲  王志琴  杨建昌  朱庆森 《中国农业科学》2003,36(12):1456-1461

 以籼型三系杂交稻汕优 63为材料 ,对不同氮肥管理的农艺和经济表现进行了评价。结果表明 ,未施氮肥 (空白区 )的产量为 6.8～ 7.4t·ha- 1,表明试验田背景氮颇高。与农民习惯施肥法 (氮肥 2 40kg·ha- 1)相比 ,改良的农民施肥法 (农民习惯施氮量的 70 % )、实时氮肥管理 (依据叶绿素仪测定值进行的施肥方法 )和实地氮肥管理(施氮时期、施氮量和叶绿素仪测定值相结合的施肥方法 )分别增产 9.2 %～ 10 .3 %、3 .3 %～ 7.0 %和 8.9%～ 9.3 % ,氮肥农学利用率分别提高了 110 .5%～ 13 5.6%、2 0 4.3 %～ 2 97.0 %和 2 0 0 .9%～ 2 76.4%。以上结果表明 ,在产量不降低甚至有所增加的前提下 ,实时、实地氮肥管理可以减少氮肥施用量 ,较大幅度地提高水稻氮肥利用率。另外 ,实时、实地氮肥管理还可以降低稻米的垩白率和垩白度 ,改善稻米的外观品质  相似文献   

北京市城区近郊区生活垃圾成分调查及可农用性分析     

刘克锋  石爱平  王红利  刘悦秋  刘彩玲  邢汝明 《农业环境科学学报》2002,21(3):232-236

对北京市城区和近郊区的新鲜城市生活垃圾进行了分类调查和理化性质测定。结果表明:(1)新鲜生活垃圾可农用部分占84.04%,冬季可农用部分所占比率高;(2)垃圾肥料有机质含量在12.50%—19.70%范围,全氮在0.53%—0.87%范围;(3)垃圾肥料重金属含量和残毒含量符合国家卫生标准和城市垃圾农用控制标准。建议垃圾肥料与处理过的禽畜粪便混合,可生产出优质有机肥料。  相似文献   

Single-Electron Transport in Ropes of Carbon Nanotubes     

M Bockrath  DH Cobden  PL McEuen  NG Chopra  A Zettl  A Thess  RE Smalley 《Science (New York, N.Y.)》1997,275(5308):1922-1925

The electrical properties of individual bundles, or "ropes," of single-walled carbon nanotubes have been measured. Below about 10 kelvin, the low-bias conductance was suppressed for voltages less than a few millivolts. In addition, dramatic peaks were observed in the conductance as a function of a gate voltage that modulated the number of electrons in the rope. These results are interpreted in terms of single-electron charging and resonant tunneling through the quantized energy levels of the nanotubes composing the rope.  相似文献   

Still going strong, community forests in Sweden   总被引：2，自引：0，他引：2  

Carlsson  L 《Forestry》1999,72(1):11-26

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