The problem of meeting dietary protein requirements in intensive aquaculture of marine fish larvae, with emphasis on Atlantic halibut (Hippoglossus hippoglossus L.)   总被引：1，自引：0，他引：1  

A. KVÅLE  A. NORDGREEN  S.K. TONHEIM  & K. HAMRE 《Aquaculture Nutrition》2007,13(3):170-185

Atlantic halibut (Hippoglossus hippoglossus) achieve a mature gastrointestinal tract approximately 2 months after first feeding (12 °C). The immature digestion may be the reason that compound diets fail to sustain growth and survival in first feeding halibut larvae and in larvae of other marine fish species. On the other hand, larvae fed with live feeds are capable of extraction of sufficient quantities of nutrients to sustain high growth rates. A lower availability of the protein in formulated diets compared with live prey is considered to be an important reason for the low performance of formulated diets. One approach to increase dietary protein availability is supplementation of pre‐digested proteins. Experiments using tube fed individual larvae show that halibut larvae are able to utilize hydrolysed protein more efficiently than intact protein. However, Atlantic halibut in culture did not respond well to dietary supplementation of hydrolysed protein, in contrast to some other species. One reason may be extensive leaching of pre‐hydrolysed proteins from the microparticulate feed. Atlantic halibut are slow feeders and may thus suffer more from nutrient leaching than species eating more rapidly. Feed formulation techniques affect dietary protein leaching, and in this paper, different techniques and their impact on feed properties are described. Microbound diets are most widely used in larval rearing, but show high rates of nutrient leaching. Lipid‐based capsules seem to have the best potential to prevent leaching, however, they are not able to deliver a complete diet. The high need for improvements in larval feed formulation techniques are clearly stated, and some suggestions are given. Among these are production of complex particles, where small lipid‐based capsules or liposomes containing the low molecular weight water‐soluble nutrients are embedded. In such feed particles the water‐soluble molecules are protected from leaching. Techniques for delivery of water‐soluble nutrients that are needed in large quantities, i.e. free amino acids or hydrolysed and water‐soluble protein, remain to be developed.  相似文献   

不同种植年限山银花根区土壤生物特性   总被引：2，自引：1，他引：2  

张珍明  乐乐  林昌虎  何腾兵 《水土保持通报》2015,35(5):71-76

[目的]探索喀斯特山区不同种植年限对山银花产地土壤生物学特性的影响,为促进贵州省山银花的高产优质栽培提供基础数据。[方法]采用野外采集和室内分析的方法,以贵州省绥阳县不同种植年限山银花根区土壤为研究对象,对比研究了不同年限土壤生物特征。[结果]随着种植年限的增加,山银花土壤微生物总数和细菌数量(B)在数值上表现为先增加后减少的趋势,放线菌数量(S)和真菌数量(F)呈不断增加的变化趋势;土壤微生物生物量碳、生物量氮和微生物量磷都表现为先增加,后持续减少的趋势;土壤过氧化氢酶和脲酶的活性均有先增加后减少的趋势,土壤磷酸酶有先减少后缓慢增加的趋势;土壤细菌和真菌数比值(B/F)呈先增加后减少趋势,放线菌数量(S)和真菌数量比(S/F)随着种植年限的增加而增加;土壤微生物的Shannon—Wiener指数随着种植年限先增大后减小,Simpson指数和Shannon均匀度指数均随着种植年限呈减少趋势。[结论]随着种植年限的增加,土壤肥力下降,根区病毒害发病率增大。  相似文献   

松突圆蚧在我国潜在的适生分布区研究     

魏初奖  陈顺立  乐通潮 《福建林学院学报》2013,(2):165-169

为较准确地预测松突圆蚧在我国潜在的适生分布区域,笔者根据松突圆蚧的生物学、生态学特性以及寄主植物分布状况等,综合分析影响该虫生长发育的主要因子,据此应用地理信息系统分析其潜在的适生分布范围,获得了直观、明晰的松突圆蚧潜在的适生区分布图及风险等级区划图。结果表明,台湾、广东、澳门、香港、广西和福建的大部分及湖南、江西、云南南部地区为松突圆蚧潜在的1级风险区;海南、云南的中部以北地区、湖南与江西的北部、福建东北与西北部、浙江、江苏、安徽、湖北、重庆、贵州、河南、山东和河北中南部、四川东南部、陕西与山西中部以南等地区为松突圆蚧潜在的2级风险区;西藏南部、云南西北部、四川中西南部、甘肃东南部、宁夏、陕西北部、河北西部及辽宁的南部为松突圆蚧的3级风险区。据统计,其潜在分布区域的国土面积占全国国土总面积的41.5%,占我国松树分布面积的90%以上,其中1级风险、2级风险和3级风险区域的国土面积占潜在适生分布区国土总面积的比例分别为18.9%、58.7%和22.4%。  相似文献   

基于树枝状嵌段共聚物的载药微球的制备及其药物释放表征     

崔嘉扬  乐黄莺  沈振陆 《上海交通大学学报(农业科学版)》2012,30(6):6-13

为建立一种树枝状共聚物载药微球的制备方法及其药物释放行为的体外评价机制,研究采用实验室自制的4代树枝状大分子引发剂PEG-G4-(OH)32引发己内酯开环聚合,合成了一系列树枝状三嵌段共聚物,并对其结构进行了表征;采用乳液-溶剂挥发法制备了共聚物-紫杉醇载药微球。研究结果显示,以树枝状嵌段共聚物为壁材的载药微球形貌规整,表面平滑,粒径范围为1.92～2.54μm,载药量为15.7%～20.6%;在0～3d的时间里载药微球释药明显,在随后的3～15d的时间里基本呈现线性的零级释放效果。该研究首次采用树枝化聚己内酯的嵌段共聚物制备载药微球,与以线性聚己内酯为壁材制备的载药微球进行了对比,结果表明,前者药物缓释效果更好,具有一定的临床应用前景。  相似文献   

杂交榛不同枝段绿枝扦插生根特性及相关氧化酶活性变化   总被引：3，自引：1，他引：3       下载免费PDF全文

勒栋梁  董凤祥  李宝  王贵禧 《林业科学研究》2009,22(4)

采用简单重复扦插试验,设置发育枝上、中、下段和萌蘖上段浸蘸1 500 mg·L-1 IBA,清水处理为对照,3次重复,研究了杂交榛绿枝不同枝段生根特性和生根指标差异及扦插后不同时期、不同枝段皮部的过氧化物酶(POD)、多酚氧化酶(PPO)和吲哚乙酸氧化酶(IAAO)的活性变化.结果表明:杂交榛子绿枝扦插以表皮生根为主,不同枝段部位在生根时期和生根指标上存在差异;幼嫩的上段插穗从扦插至生根只需13 d,而中段和下段分别需要19、22 d;发育枝上、中、下段和萌蘖上段经1 500 mg·L-1IBA处理的生根率、根数、根长显著高于对照,发育枝上段生根最好,萌蘖上段、发育枝中段和下段生根能力依次降低.扦插后POD活性呈上升趋势,至第1根出现期达到最大(峰值),处理和对照间、不同枝段间在峰值处存在差异,发育枝上、中、下段POD活性在峰值处的大小与其扦插生根率呈极显著正相关;PPO活性在扦插生根过程中呈现一定的双峰特性,扦插时至愈伤形成期PPO活性有一个增高期,诱导期至第1根形成期PPO活性第2次快速提高,至第1根形成期PPO活性达到最达值,之后有所下降;IAAO在愈伤形成期和第1根形成期之间的表皮瘤状突起形成期(诱导期)达到最大.  相似文献   

论日本茶道与宋代斗茶之渊源     

乐素娜 《茶叶》2010,36(4):253-255

中国的茶与茶文化,对日本的影响甚为深刻,日本茶道的发祥与中国文化的熏陶息息相关。日本茶道与宋代时期流行的茶礼有许多共同点,两国的茶文化也有诸多共通之处。  相似文献   

有机生产系统中甜瓜果实发育和糖分积累研究   总被引：2，自引：0，他引：2  

乐建刚  宋世威  Philipp Lehne  黄丹枫  吴才君 《江西农业大学学报》2007,29(4):526-532

研究了有机和常规生产系统中不同施肥水平对网纹甜瓜果实发育和糖分积累的影响。结果表明:有机和常规生产系统以及施肥水平都未改变甜瓜果实发育和糖分积累规律。果实鲜重和果肉厚度的增长均呈"S"形曲线变化,可溶性固形物(TSS)和糖分积累呈二次型曲线变化。甜瓜果实在进入成熟期前,以葡萄糖和果糖积累为主,进入成熟期,蔗糖积累迅速,总糖含量持续上升。果实TSS增长趋势与总糖相同,两者呈极显著正相关(春季r=0.884**,秋季r=0.958**)。春季有机生产甜瓜采收期的果实重量显著高于常规生产,而秋季两者差异不显著。生产系统和施肥水平对果实TSS和糖分含量都没有影响。由于春季甜瓜果实发育时段的积温高,采收期果实重量和果肉厚度分别比秋季高28%和9.0%。甜瓜果实的生长量受积温的影响较大,有机生产系统和施肥水平不影响果实糖分积累。  相似文献   

Salmonella Dublin infection in Queensland dairy cattle     

KF TRUEMAN  RJ THOMAS  AR MACKENZIE  LE EAVES  PF DUFFY 《Australian veterinary journal》1996,74(5):367-369

Objective: To investigate the presence of Salmonella Dublin in Queensland cattle.
Design: An epidemiological study using diagnostic laboratory information and farm records.
Procedure: Outbreaks of gastroenteritis or pneumonia in calves, and abortions and enteritis in cows were routinely investigated for the presence of salmonellae. Where S Dublin was isolated, attempts were made to gather further epidemiological information.
Results: Prior to 1983 only two outbreaks of S Dublin have been recorded in Queensland dairy cattle. In 1983 S Dublin abortions were diagnosed in dairy heifers introduced from southern Australia to south-east Queensland. Sampling indicated that at least 10% of the 500 introduced heifers were faecal excretors of S Dublin. On 3 of the 7 farms from which S Dublin was recorded, infection spread to other cattle that were in contact. From February 1985 to February 1996, 29 outbreaks of S Dublin in cattle occurred on 29 farms (28 in south east Queensland and 1 in north Queensland). Calves were primarily affected. Continuing outbreaks were confirmed on only 4 of these 29 farms. On 15 farms S Dublin infections were associated with the purchase of infected calves or cows, while another farm adjoined 2 previously infected farms. No source of S Dublin was evident for the other 13 farms, where histories were often inadequate.
Conclusion: There has been a marked increase in S Dublin outbreaks in Queensland dairy cattle since 1983. Introduction of S Dublin carrier and aborting dairy heifers from southern Australia, where S Dublin is not uncommon, was associated with the initial outbreaks.  相似文献   

EFFICIENCY OF RAFOXANIDE AND NAPHTHALOPHOS AGAINST INHIBITED HAEMONCHUS CONTORTUS     

L.F. LE  JAMBRE I.A. BARGER 《Australian veterinary journal》1979,55(7):346-347

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Elimination of Staphylococcus intermedins in healthy dogs by topical treatment with fusidic acid     

L. Saijonmaa-Koulumies  E. Parsons  D. H. Lloyd 《The Journal of small animal practice》1998,39(7):341-347

Cutaneous and mucosal carriage of Staphylococcus intermedius was investigated in six healthy beagles before and after application of fusidic acid to mucosal surfaces as 1 per cent viscous eye drops twice daily for seven days. Bacterial populations were determined repeatedly over four weeks using quantitative techniques. The overall cutaneous populations of S intermedius reduced significantly (P<0·01) two days after treatment but returned to pretreatment levels after a further week. The mucosal frequency of S intermedius reduced significantly (P<0·001) two days after treatment and remained reduced (P<0·01) at the end of the study. The mucosal populations were also reduced (P<0·01) two days after treatment and remained lower (P<0·05) after a further week. No such changes occurred in the control group of six beagles. The study indicates the importance of mucosae as carriage sites for S intermedius in dogs. This form of therapy may be useful as an additional tool against canine recurrent pyoderma.  相似文献