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Kim Birnie‐Gauvin Lasse Birch Hjrup Theis Kragh Lene Jacobsen Kim Aarestrup 《Ecology of Freshwater Fish》2019,28(3):376-384
Pike (Esox lucius) occupy coastal streams and rivers of the Baltic Sea, where they attain large sizes (>5 kg). These large sizes are perhaps due to the fact that they can tolerate relatively high salinities and can thus forage in the nearby more productive brackish environments. In an attempt to quantify the extent to which pike utilise brackish environments, and to provide some insight into the underlying causes for brackish water migrations, we tagged 30 pike from a western Baltic river with acoustic transmitters and were able to track 21 individuals for 1 year. Based on experienced from local anglers, this population was assumed to be brackish in nature, where individuals underwent freshwater migrations to spawn. Our findings however suggest that the smallest and most active individuals make short exits into brackish waters and do so on rare occasions. Our results further indicate that neither sex nor size is related to activity level. We suggest that these patterns reflect two distinct behaviours—active and passive—and that large pike can be supported by the food availability in the river, without the need to venture into coastal zones, thus defying the conventional view that Baltic pike are all brackish in nature. 相似文献
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Viral and bacterial agents associated with experimental transmission of infectious proventriculitis of broiler chickens. 总被引:1,自引:0,他引:1
G R Huff Q Zheng L A Newberry W E Huff J M Balog N C Rath K S Kim E M Martin S C Goeke J K Skeeles 《Avian diseases》2001,45(4):828-843
Proventriculitis of broilers can be reproduced by oral inoculation of day-old chicks with a proventricular homogenate from affected 3-wk-old broilers. The objective of the following studies was to isolate from this homogenate viral and bacterial isolates that could produce proventriculitis. A monoclonal antibody to infectious bursal disease virus (IBDV) was used to precipitate virus from the homogenate. A primary chicken digestive tract cell culture system was also used to isolate virus from a 0.2-microm filtrate of the homogenate, and a bacterium was also isolated from the homogenate. In trial 1, day-old birds were orally inoculated with either proventriculus homogenate or monoclonal antibody immunoprecipitated IBDV (MAB-IBDV). At 4, 7, 14, and 21 days postinfection (PI), 12 birds from each treatment group were subjected to necropsy. In trial 2, day-old birds were orally inoculated with either infectious proventriculus homogenate, suspect virus isolated in cell culture and propagated in embryo livers and spleens, or a bacterial isolate. Twelve birds from each treatment were subjected to necropsy at days 7, 14, 21, and 28 PI. In trial 3, treatments were maintained in negative pressure isolation chambers, and an additional treatment included virus plus bacterial isolate. Twenty-four birds from each treatment were subjected to necropsy at day 21 PI. In trial 1, infectious homogenate decreased body weight and relative gizzard weights at 4, 7, 14, and 21 days PI. Proventriculus relative weight was increased at days 7, 14, and 21 PI, and proventriculus lesion scores were increased at days 14 and 21 PI. Bursa/spleen weight ratios were decreased at day 14, and feed conversion was increased at days 4 and 21. The MAB-IBDV treatment decreased proventriculus and gizzard relative weights at day 4 PI, increased proventriculus lesion scores and bursa/spleen weight ratios at day 14, and decreased heterophil/lymphocyte ratios at day 21. In trial 2, all infected birds had significantly higher mean relative proventriculus weights at 21 days PI and had higher 4-wk mean proventriculus scores as compared with both control groups. In trial 3, birds treated with homogenate and birds treated with both suspect virus and the bacterial isolate had significantly higher proventriculus lesion scores; higher relative weights of proventriculus, gizzard, liver, and heart; lower body weights; and lower relative bursa weights compared with the saline control group. These studies suggest that infectious proventriculitis has a complex etiology involving both viral and bacterial infection. 相似文献
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用两株单克隆抗体混合后包被ELLISA微孔板,加牛冠状病毒抗原,加经白陶土处理过的兔抗牛冠状病毒免血清,再加上辣根氧化物酶标记的羊抗兔IgG抗体,加底物质显色间接ELISA检测牛冠状病毒抗原获得成功。用此方法检测细胞培养的牛冠状病毒上清液,其敏感度高出血凝试验(HA)8倍,从武汉市附近3个奶牛场采集犊牛腹泻粪便105份,用单抗ELISA检测牛冠状病毒抗原,共检出阳性36份,并与血凝及血凝抑制试验, 相似文献
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Verification by polymerase chain reaction of vertical transmission of Theileria sergenti in cows 总被引:2,自引:0,他引:2 下载免费PDF全文
Byeong K. Baek Kim B. Soo Jin H. Kim Jin Hur Bou O. Lee J. M. Jung Misao Onuma Anthony O. Oluoch Chang-Hyun Kim Ibulaimu Kakoma 《Canadian journal of veterinary research》2003,67(4):278-282
To evaluate the transplacental transfer of Theileria sergenti infection in cattle, we used DNA probes to detect T. sergenti in 6 pregnant cows and their calves. All the animals were monitored by parasitologic, serologic, and polymerase chain reaction (PCR) assays for a predicted 875-base-pair (bp) DNA product and a 684-bp amplicon detected by nested PCR in the blood and spleens of aborted fetuses. An open reading frame (ORF) starting at nucleotide 170 and terminating at position 1021 was shown to code for a polypeptide of 283 amino acid residues. All 6 dams and 5 calves were positive for T. sergenti in all tests. One calf was positive only with nested PCR. We conclude that transplacental transmission of T. sergenti is a significant problem. The relevance of the data in the programmed introduction of new (especially pregnant) animals into established clean herds needs serious consideration with regard to control of theileriosis and other tickborne diseases. 相似文献
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I.-S. Park G. C. Choi D. S. Kim Y. K. Nam 《Journal of the World Aquaculture Society》2002,33(4):494-500
For the evaluation of hormonal control of spermiation in fish, a method to quanify the spermiation response of mature Rhynchocypris oxycephalus (Sauvage and Dabry) to hormonal therapy is described. Spermatocrit was determined after 7 min centrifugation at 18,000 ± g and sperm density was estimated by a standard hemocytomer method. Sperm density can be predicted from spermatocrit since their relationship is linear as described by the regression equation, Y = 3.68X - 27.18 ( R 2 = 0.82, N = 50). where Y is spermatocrit and × is sperm density. Milt production by mature R. oxycephalus was highest at 24 h after injection of 1,000 IU human chorionic gonadotropin (HCG) and 50 μg luteinizing hormone-releasing hormone analogue (LHRHa) per kg body weight. Increased milt production coincided with low spermatocrit and sperm density levels. These results demonstrate that spermiation in mature R. oxycephalus can be reliably evaluated by a spermatocrit method and that HCG and LHRHa are effective in stimulating of spermiation in this species. 相似文献
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1986年我们从加拿大碧青种子公司引进牧草种子24份,其中豆科7份,禾本科17份,于当年秋播。从3年试种结果看,Glory苜蓿、Minto苜蓿、Algonquin苜蓿在北京种植,无论是产草量、种子产量、草质还是适应性均表现良好。Leo百脉根在北京可安全越冬,其特点是夏季生长繁茂,草质好,耐牧,耐践踏。Orbit长穗冰草、Chief 中间冰草、阿尔泰野麦草表现为抗寒耐旱,产草量高,但要适时利用,否则会降低饲用价值。俄罗斯野麦草、Nordan沙生冰草、草地看麦娘、猫尾草产草量一般,但草质好,春季返青早,枯黄期晚,可在京郊西部山区种植。无芒雀麦(2份)、鸭茅、牛尾草、(艹鹝)草(3份)均表现为适应性好,草质优,产草量高,是较好的禾本科牧草。白三叶、草地早熟禾可做为地被植物和草坪草。 相似文献