肉仔鸡低血糖-尖峰死亡综合征的流行病学分析和病原初探     

吴延功梁万友  徐书永王志亮 魏荣陈正平  张德新 《中国动物检疫》2005,22(8):20-22

自2003年6月份以来，在我国北方肉鸡饲养基地普遍流行了一种主要侵害肉仔鸡的疾病，低血糖-尖峰死亡综合征(HSMS)。HSMS发病日龄集中于10～18日龄．临床表现为突然出现的高死亡率，病鸡头部震颤、运动失调、昏迷、失明、死亡。先后对黑龙江、吉林、辽宁、内蒙古、天津、河北、山东等省进行调查．发现HSMS在这几个省的很多肉鸡饲养区广泛存在。对发生该病的259个肉鸡饲养户的调查结果显示．该病与祖代种鸡没有关系．病原可能来自受污染的父母代种鸡场。平均发病率为17．9％。发病鸡群血糖浓度极显著的下降。从2个发病鸡群的病鸡肠道内容物中观察到病毒颗粒．病毒呈多形性．有囊膜，直径约80-100nm，表面有棒状纤突，长约10-20nm．与冠状病毒类似。  相似文献   

Demographic trends in Claremont California’s street tree population     

《Urban Forestry & Urban Greening》2018

The aim of this study was to quantify street tree population dynamics in the city of Claremont, CA. A repeated measures survey (2000 and 2014) based on a stratified random sampling approach across size classes and for the most abundant 21 species was analyzed to calculate removal, growth, and replacement planting rates. Demographic rates were estimated using a hierarchical Bayesian framework. The community-level (all species) median growth rate was 1.41% per year (95% CI: 1.21–1.65%) with Pinus brutia and Pistacia chinensis growing significantly faster than the community-level median. The community-level median removal rate was 1.03% per year (95% CI: 0.66–1.68%), with no significant differences between species and the community-level medium. Once removed, only 7.2% (95% CI: 4.4–12.9%) were replaced annually. Presence of overhead utility lines influenced tree removal rates while age, diameter-at-breast-height, and prior tree condition influenced tree growth. Overall live aboveground biomass in sampled sites was 713.29 Mg in 2000 and increased to 877.36 Mg by 2014. Biomass gain from growth outweighed loss from removals nearly three-fold; replacement contributed 0.5% of the total biomass gain. We conclude that to increase the resilience of the street tree population will require 1) an increase in percent of full stocking or biomass stock and 2) a shift in the species palette to favor species less vulnerable to pests and expected disturbance from climate change and 3) ongoing monitoring to detect departures from baseline demographic rates.  相似文献   

Predicting the age of fish using general and generalized linear models of biometric data: A case study of two estuarine finfish from New South Wales, Australia     

Faith A. Ochwada  James P. Scandol  Charles A. Gray 《Fisheries Research》2008,90(1-3):187-197

Direct ageing of fish can be a laborious and expensive task when age estimates from a large population are required, and often involves a degree of subjectivity. This study examined the application of general and generalized linear models that predict the age of fish from a range of efficiently and objectively measured covariates. The data sampled were from yellowfin bream (Acanthopagrus australis (Sparidae) (Owen, 1853)) and sand whiting (Sillago ciliata (Sillaginidae) Cuvier, 1829) populations from New South Wales, Australia. The covariates evaluated in the models were fish length, otolith weight, sex and location (the estuary from which the fish were sampled). Akaike Information Criteria were used for model selection and residual plots of the final models revealed a satisfactory fit to the observations. The best fitting model for each species included all covariates. An additional investigation considered whether general and generalized linear models that predict age from two different categories of biometric information outperform age-length keys with respect to subsequent estimates of total mortality from catch-curve analysis. The two categories of biometric information differed in the ease and cost with which the information could be collected. The first category only included fish length and location as covariates, whilst the second category also included otolith weight and sex. It was found that traditional age-length keys outperformed the predictive models that estimated age from only fish length and location, because the results from the models were prone to significant bias. However, when otolith weight and sex were added as covariates to the predictive models, some of them, including a generalized linear model with a Poisson-distributed response variable, performed similarly to the age-length key. Given that otolith weight and the sex of fish are cheaper to quantify than age from a sectioned otolith in many situations, general or generalized linear models may represent a cheaper and faster method of estimating mortality compared to age-length keys. Such models can also easily incorporate the influence of spatial, temporal and demographic variation.  相似文献   

Seabird mortality at trawler warp cables and a proposed mitigation measure: A case of study in Golfo San Jorge, Patagonia, Argentina     

Diego González-Zevallos  Pablo Yorio  Guillermo Caille 《Biological conservation》2007,136(1):108-116

We studied the interaction between seabirds and warp cables in the high-seas Argentine hake Merluccius hubbsi trawl fishery operating in Golfo San Jorge, Argentina, and tested the efficacy of a simple mitigation measure designed to reduce mortality at warp cables. Observations were made onboard hake trawlers during the height of the fishing season, between December 2004 and April 2005. Thirteen seabird species used food made available by fishing operations. The most frequent and abundant seabirds (% occurrence, mean maximum number per haul) were the Kelp gull Larus dominicanus (98.1%, 348.5) and the Black-browed albatross Thalassarche melanophrys (96.1%, 132.2). Contacts with warp cables were recorded for six species in 81.4% of hauls, with a mean number of contacts per haul of 14.4 ± 23.8 (range = 0-127). A total of 53 individuals were killed due to interactions with nets and cables, resulting in a total cable mortality rate of 0.14 birds/haul. Considering the fishery’s fishing effort, the estimated total number of birds killed during the study was 2703 (CV = 0.8), of which 306 (CV = 0.9) were killed due to contacts with warp cables (255 Kelp gulls and 51 Black-browed albatross). The tested device consisted of a plastic cone attached to each warp cable. In hauls with mitigation device, the number of contacts was reduced by 89% and no seabirds were killed. Mean distances between seabirds and cables were significantly larger in hauls with than without mitigation device (2.6 vs 0.9 m). The proposed device could be easily applied in this and other trawl fisheries operating in Argentine waters. Increased effort should be placed in implementing mitigation measures and the monitoring of cable related mortality associated to high-seas trawlers operating in the Argentine Continental Shelf.  相似文献   

Use of Akaike information criteria for model selection and inference. An application to assess prevention of gastrointestinal parasitism and respiratory mortality of Guinean goats in Kolda,Senegal     

Lancelot R  Lesnoff M  McDermott JJ 《Preventive veterinary medicine》2002,55(4):993-240

A field experiment was carried out in Kolda (southern Senegal) from July 1986 to July 1988. Its goals were to: (1) describe the patterns of mortality of female Guinean goats by age, season and year; (2) assess preventive measures against respiratory diseases and gastrointestinal parasitism in reducing mortality; and (3) estimate the overall impact of these measures on survival to 1 year of age. Preventive measures for respiratory disease included vaccination against peste des petits ruminants (PPR) and pneumonic pasteurellosis (Pasteurella multocida types A and D). Control of gastrointestinal parasites was by deworming does with morantel (7.5 mg kg⁻¹, three times during the rainy season). The effects of vaccines and deworming were tested in a randomised factorial field experiment with villages being the experimental units. A total of 19 villages, 113 goat herds and 1458 goats were included in the study.

Generalised linear models of survival for five cohorts of goats (defined by five different birth seasons) used a binomial assumption for the response distribution and a complementary log–log link. Explanatory variables included age, season, year, vaccination, deworming and their interactions. A complex a priori model was built on the basis of previous epidemiological knowledge; a purposively selected set of simpler models was compared to this full model by the Akaike information criterion (AIC) and derived statistics. Inference on 1-year survival and treatment effects accounted for model-selection uncertainty. It was carried out with a bootstrap procedure and used information from the whole set of selected models.

Large variations in mortality by year and season were observed but no regular seasonal pattern was apparent. Mortality probabilities of kids in dewormed groups decreased quickly after birth, but remained elevated up to 9 months of age in the non-dewormed groups. Deworming lowered the risk of mortality. Vaccination alone was not protective (except during an observed outbreak of PPR).  相似文献   

Mortality and recovery of runt white sturgeon (Acipenser transmontanus) in a commercial farm in California, USA     

Georgiadis MP  Hedrick RP  Johnson WO  Gardner IA 《Preventive veterinary medicine》2000,43(4):269-281

We investigated the effect of raising runt white sturgeon (Acipenser transmontanus) separately from dominant fish during the initial stages of grow-out in a commercial farm. Runt fish are poor-growers, have underdeveloped muscle mass, swim slowly and are more-frequently found at the top of the water column. The objective of the study was to describe the mortality and recovery rates (and their determinants) of white-sturgeon runts after separating them from dominant fish. Runt white sturgeon were stocked into twelve 2 m × 2 m rectangular tanks and graded periodically during a follow-up of 46–102 days. Overall mortality rates ranged from 0.3 to 7 dead fish per 1000 sturgeon-days at risk and overall recovery rates from 3.9 to 13.5 recovered fish per 1000 sturgeon-days at risk. Period-specific mortality and recovery rates increased over time. The period-specific mortality rates for all three periods were significantly higher for tanks of runts originating from grow-out tanks with high mortality (p-values: first period = 0.06; second period = 0.09; third period = 0.03), but were similar for tanks of runts of high- and low-mean initial weight. The period-specific recovery rates were significantly higher in runts originating from high-mortality grow-out tanks only for the third period (p = 0.05) but not the first and second periods (p-values = 0.33 and 0.25, respectively). Recovery rates were significantly higher in the higher-mean-weight runts tanks for the first and third period but not for the second (p-values: first period = 0.02; second period = 0.65; third period = 0.06). We concluded that the proportion of runts that recover during a 46–89 day period is substantial (16–58%); therefore, it might be worthwhile growing such fish separately in a fish farm for about three months. Financial analysis showed that this practice was profitable, if the value of white sturgeon fish for the farm exceeded $2.05 per kg.  相似文献   

Retrospective analysis of trends and production factors associated with sow mortality on swine-breeding farms in USA   总被引：2，自引：0，他引：2  

Koketsu Y 《Preventive veterinary medicine》2000,46(4):249-256

Of the 825 pig farms in USA that mailed in their electronic file containing production records, 604 farms were used to observe breeding-female mortality risk and related factors (herd size, lactation length, parity and season). Multiple regression was used to determine factors associated with annual mortality risk. Analyses of variance were used for comparisons of mortality risks among parity and season groups. Average annual mortality risks during the 1997 period was 5.68%. Average breeding-female inventories and average lactation length on USA farms were 733 and 18.3 days, respectively. Higher annual breeding-female mortality risk was associated with larger herd size, greater parity at farrowing and shorter lactation length (P<0.02). For example, as herd size increases by 500 females, mortality risk increases by 0.44%. Older parity was associated with higher mortality risks. Summer season was also associated with higher mortality risk. Using five-years’ records on 270 farms, annual mortality risk in 1997 was higher than those of 1993 and 1994, while average breeding-female inventory increased and lactation length decreased. It is recommended that producers, especially in large herds, pay more attention to breeding females.  相似文献   

Passive transfer of colostral immunoglobulins in calves     

Weaver DM  Tyler JW  VanMetre DC  Hostetler DE  Barrington GM 《Journal of veterinary internal medicine / American College of Veterinary Internal Medicine》2000,14(6):569-577

Passive transfer of colostral immunoglobulins has long been accepted as imperative to optimal calf health. Many factors, including timing of colostrum ingestion, the method and volume of colostrum administration, the immunoglobulin concentration of the colostrum ingested, and the age of the dam have been implicated in affecting the optimization of absorption. The practice of colostrum pooling, the breed and presence of the dam, and the presence of respiratory acidosis in the calf also may affect passive transfer. Various tests have been reported to accurately measure passive transfer status in neonatal calves. The radial immunodiffusion and the enzyme-linked immunosorbent assay (ELISA) are the only tests that directly measure serum IgG concentration. All other available tests including serum total solids by refractometry, sodium sulfite turbidity test, zinc sulfate turbidity test, serum gamma-glutamyl transferase activity, and whole blood glutaraldehyde gelation estimate serum IgG concentration based on concentration of total globulins or other proteins whose passive transfer is statistically associated with that of IgG. This paper presents a comprehensive review of the literature of passive transfer in calves including factors that affect passive transfer status, testing modalities, effects of failure of passive transfer on baseline mortality, consequences of failure of passive transfer, and some treatment options. Many previously accepted truisms regarding passive transfer in calves should be rejected based on the results of recent research.  相似文献   

鹅副粘病毒感染鸡试验   总被引：7，自引：0，他引：7  

周继宏  田慧芳  王永坤 《中国预防兽医学报》2000,22(1):3-4

本室分离的鹅副粘病毒是一侏对鹅具有料强致病毒，它也能实验感染雏鸡，且雏鸡感染后发病率均为１００％，死亡率５０％以上。人工感染的鸡其症状和病理变化均与鹅自然发病的病变相类似。从感染途径看，注射接触（混养）均能感染发病，并且在感染发病及死亡时间上也与鹅感染情况相似，因此该病毒感染鹅同时又能实验感染雏鸡，而且传播之迅速，危害之严重必须引起养禽户的重视。  相似文献   

Estimating the production and mortality of fine roots in a Japanese cedar (Cryptomeria japonica D. Don) plantation using a minirhizotron technique     

Kyotaro Noguchi  Tadashi Sakata  Takeo Mizoguchi  Masamichi Takahashi 《Journal of Forest Research》2005,10(6):435-441

Fine roots are a key component of forested ecosystems, but available information is still limited. This study examined the production and mortality of fine roots less than 1 mm in diameter in a Japanese cedar (Cryptomeria japonica D. Don) plantation located on the Kanto Plain in central Japan. We used a minirhizotron technique in combination with soil coring, and collected data for 1 year (May 2002–May 2003). Fine root production and mortality were determined from changes in the lengths of individual fine roots on minirhizotron tubes. Both fine root production and mortality rates were greater in the upper soil than in lower soil levels. Both rates were seasonal, with higher values in summer than in winter; this trend was more pronounced in upper soil levels. These results suggest that environmental conditions, such as temperature or soil properties, affect the production and mortality rates of fine roots. Fine root production and mortality occurred simultaneously, and their rates were similar, which may have led to unclear seasonal changes in fine root standing crop estimates. Soil coring indicated that the fine root biomass of this stand was about 120 g m⁻², of which 40% was from Japanese cedar. The estimated rates of dry matter production and mortality of total fine roots, including understory plants, were both approximately 300 g m⁻² year⁻¹.  相似文献