Feeding selectivity of the marine ascidian Styela clava     

Jiang Ai-li  Yu Zhen  Cai Wen-gui  & Wang Chang-hai 《Aquaculture Research》2008,39(11):1190-1197

The sessile suspension feeding ascidian, Styela clava , plays an important role in the functioning of estuarine systems. The feeding selectivity of S. clava was examined using standard physiological techniques in terms of particle sizes and diet concentrations. Styela clava increased its retention efficiency (the proportion of available particles retained in ascidian) with increasing particle size at a lower diet concentration [expressed as particulate organic matter (POM)] from 2.11 to 10.06 mg POM L⁻¹, and the highest retention was reached for 5–20 μm particles. With increasing diet concentration to 20.12 mg POM L⁻¹, S. clava retained small particles (<3.5 μm) more efficiently and large ones (>15 μm) less efficiently. The selectivity of ascidian with different sizes was similar at the same concentration. At every diet concentration, larger ascidians retained more 5–20 μm cells than the smaller ones. All these results indicate that S. clava possesses a particle selection mechanism that may affect the zooplankton communities to a certain degree.  相似文献   

古尔班通古特沙漠南缘脊椎动物群落的摄食集团及其生态适应   总被引：2，自引：0，他引：2  

胡德夫  贾泽信 《干旱区研究》1998,15(1):64-68

本文依据实地观测资料，探讨了古尔班通古特沙漠南缘区脊椎动物群落各摄食集团的动种构成及其随物候期食物资料变化所产生的相应分化和转换，揭示出该区域脊椎动物食集团具有不稳定的特征，分析得出，少数生态适应性强的物种摄食量集团的分化是维系沙质荒漠生态系统完整性的重要生态过程，它介研究脊椎动物群落营养结构动态的关键摄食集团。  相似文献   

Interannual variation in the availability and utilization of euphausiids as prey for Pacific hake (Merluccius productus) along the south-west coast of Vancouver Island     

TANASICHUK 《Fisheries Oceanography》1999,8(2):150-156

The species and size composition of euphausiids consumed by Pacific hake ( Merluccius productus ) along the south-west coast of Vancouver Island were monitored during the 1989, 1990 and 1995–97 summer feeding seasons. Thysanoessa spinifera and Euphausia pacifica were the only euphausiid species eaten by hake. Hake persisted in selecting krill longer than 17 mm and consistently preferred T. spinifera, even though there was a substantial reduction in euphausiid abundance, a change in species composition and a shift in the size distribution to smaller individuals after the 1992–93 warm water years. The biomass of euphausiids available to hake after 1993 averaged 27% of that for 1991, the pre-ENSO year, and was 12% of the 1991 value in 1996. Hake predation was not responsible for the reduction in euphausiid abundance, as it was already low at euphausiid sizes smaller than those eaten by hake.  相似文献   

广华枝的取食量及其防治研究     

陈培昶  陈树椿  王缉健 《中国森林病虫》1998,(4)

本文研究了广华枝ＳｉｎｏｐｈａｓｍａｌａｒｇｕｍＣｈｅｎｅｔＣｈｅｎ的食叶量。其一生食叶量为２０．８０２ｇ，其中１～４龄低龄若虫期的食量占其一生食量的３．１３％，５～６（７）龄老龄若虫期的食量占２１．９５％，成虫期的食量占７４．９２％，老龄若虫期和成虫期是主要的危害期，占其一生食量的９６．８７％；并建立了个体食叶量模型、个体日均食量模型及其活动量指数增长模型，分别为Ｘ１＝０．０３９４ｅ０．５９７９Ｘ０，校正Ｒ２＊＊＝０．８９３１；Ｘ２＝２６．５１７６ｅ０．２２３３Ｘ０，校正Ｒ２＊＊＝０．７６７３；Ｘ３＝１．３０９３ｅ０．５００１Ｘ０，校正Ｒ２＊＊０．９４４０，复相关系数平方显著或极显著；胸径为８～１２ｃｍ的寄主，其防治指标为９３．１头，并提出了防治意见。  相似文献   

仔猪日常饲养管理与健康管护     

张国恩  张国晃  陈兆国 《现代农业科学》2008,(12):103-105

通过仔猪的生理特点就哺乳仔猪和断奶仔猪饲养管理与健康管护方面谈谈具体做法,还针对仔猪急病防治和饲养人员管理做了简单的介绍。  相似文献   

Migration of kawakawa Euthynnus affinis in the waters near Taiwan     

Wann-Duen  CHIOU  Liang-Kang  LEE 《Fisheries Science》2004,70(5):746-757

ABSTRACT:   Kawakawa Euthynnus affinis is the most abundant species among the small tuna in the coastal waters of Taiwan. The migration pattern of kawakawa to Taiwan was determined in the present study based on the species' feeding habits and reproductive biology and on temporal variation of catch for kawakawa and its prey fishes. Schools of this species successively migrate to Taiwan from September to May, and then move away in June. They travel to the waters off Taiwan with the warm Kuroshio current, migrate toward coastal waters for feeding and move away for spawning. It is suggested in the present study that the kawakawa spawning ground is in the waters of the northern Philippines. The migration of kawakawa exhibits size-segregating behavior. Schools of immature young fish first arrive in the coastal waters around Taiwan, followed by the adults.  相似文献   

日本对虾的实验室养殖研究     

李惠滨  傅文庆 《福建畜牧兽医》1998,(6):4-5

我们曾将发病残存的日本对虾继续养殖作为亲虾，进行夏季高温育苗，所得到的虾苗在实验室里桶养，证明在人工饲养条件下它们是可成活和生长的，本实验还提示，若能解决水质净化问题，日本对虾甚至有可能移至内陆养殖。  相似文献   

洛阳市奶业发展的现状及对策     

杜耀辉  刘洪涛 《河南科技大学学报(农学版)》2004,24(4):70-71,74

经过充分调查，认为洛阳的奶业发展现状是奶牛数量少、品质差、产量低，加工能力过剩，奶源明显不足，满足不了加工企业的需要，针对存在的问题，提出了相应的对策。  相似文献   

三疣梭子蟹早期发育阶段最佳饵料投喂策略及投喂密度探讨     

李玉全  张海艳  郑学永  王学忠  李志国 《青岛农业大学学报(自然科学版)》2009,26(4)

三疣梭子蟹是大型可食经济蟹类,具有很高的商业价值。为发展三疣梭子蟹育苗技术,试验对其早期发育阶段的饵料选择、投喂策略及最佳捕食密度进行了探讨。实验设置小球藻组、扁藻组、小球藻与扁藻混合组、轮虫组(加小球藻50×104个/ml)和卤虫组(加扁藻8×104个/ml)5个因素,分别设4、4、4、6和6个梯度。结果表明,小球藻浓度50×104个/ml或扁藻浓度8×104个/ml或小球藻(25~40×104个/ml)+扁藻(2.5~4×104个/ml)可使Ⅰ期溞状幼体(Z1)存活较长时间,但仅投喂单胞藻类不能使Z1正常变态;自Z1开始投喂轮虫可使幼体正常发育至Ⅲ期溞状幼体(Z3),以后幼体发育迟缓,出现Ⅲ期、Ⅳ期溞状幼体(Z4)和大眼幼体(M)同时存在的现象。Z1对轮虫的最佳捕食密度为5个/幼体、Ⅱ期溞状幼体(Z2)为10个/幼体,存活率可分别达到95.7%和94%;从Z3开始应该投喂卤虫无节幼体,捕食密度为10个/幼体,存活率达到最高值为84.5%。从Z4开始投喂卤虫成体,Z4、M和Ⅰ期幼蟹(C)的最佳捕食密度为10个/幼体,存活率分别为90%、85.7%和82.9%。因此,三疣梭子蟹Z1和Z2应该投喂轮虫,最佳捕食密度分别为5个/幼体和10个/幼体;Z3开始投喂卤虫无节幼体,最佳捕食密度为10个/幼体。Z4开始投喂卤虫成体,最佳捕食密度为10个/幼体。同时,育苗水体中添加一定量的单胞藻类。  相似文献   

饲喂频率对妊娠母猪背膘厚和繁殖性能的影响     

饲喂频率对妊娠母猪背膘厚和繁殖性能的影响 《畜牧与饲料科学》2022,43(2):35-40

[目的] 研究饲喂频率对妊娠母猪背膘厚和繁殖性能的影响。[方法] 挑选加系杜洛克经产母猪480头,配种时按照胎次（2~7胎）、背膘厚（11~22 mm）相近的原则随机将母猪分为T1组（每天饲喂1次）和T2组（每天饲喂2次）,两组每天等量饲喂。T1组母猪220头,饲喂时间为8：00;T2组母猪260头,饲喂时间为8：00和15：00,每次饲喂量为总量的一半,定位栏饲养。[结果] ①饲喂频率不影响妊娠56 d、开配-妊娠56 d的背膘厚（妊娠56 d背膘厚-开配背膘厚）（P>0.05）;T2组妊娠110 d（P=0.06）、妊娠56-110 d（P=0.09）背膘厚（妊娠110 d背膘厚-妊娠56 d背膘厚）有高于T1组的趋势。②饲喂频率对窝产总仔数、活仔数、死胎数、木乃伊胎数、初生窝重以及初生个体重均无显著（P>0.05）影响。③在三胎母猪中,T2组妊娠110 d（P=0.01）、妊娠56-110 d（P=0.04）背膘厚均显著高于T1组;五胎及以上母猪,T2组妊娠56-110 d（P=0.08）背膘厚有高于T1组的趋势。④饲喂频率不影响二胎母猪窝产总仔数、死胎数、木乃伊胎数、初生窝重以及初生个体重（P>0.05）,但二胎母猪中T2组活仔数有高于T1组的趋势（P=0.07）。[结论] 饲喂频率由每天两餐减少到每天一餐不会对母猪的繁殖性能产生不利影响。  相似文献