猪免疫抑制性疾病病因学研究进展

猪免疫抑制性疾病是由多种因素相互作用引起机体免疫系统损伤而导致机体抵抗力和抗病能力下降并引发各种疾病的总称。该类疾病具有感染率高、发病率高的特点,加之其发病原因多样化和复杂化,致使该病的防控难度很大,严重制约着我国养猪业的进一步发展。论文以近年来国内外研究资料为基础,分别从病原因素、猪自身因素和人为因素等方面对猪免疫抑制性疾病的病因进行了阐述,以期为该病的防控提供参考。     

牛传染性支原体肺炎流行病学与防控措施

牛传染性支原体肺炎是影响养牛产业较为严重的传染性疾病,该病主要危害3月龄~1岁的牛群,在饲养管理较差的牛场内较易暴发与流行,牛群一旦患病很难净化,对养牛业造成较大的经济损失。因此,在养牛生产中应加强对该病的预防,减少因患该病带来的经济损失。本文将对该病的流行病学特点及防控措施做以下阐述,旨在提升对该病的防控水平。     

家畜布鲁氏杆菌病的防控措施

布鲁氏杆菌病为人畜共患疾病,除危害养殖业健康发展外,还对人体健康构成威胁,我国将该病列为重点防控疫病.本文论述了家畜布鲁氏杆菌病及其防控措施,旨在为家畜该病的规范防控提供一些参考.     

我国规模猪场伪狂犬病流行状况及场间传播风险因素

猪伪狂犬病是严重危害全球养猪业的传染病。随着伪狂犬病基因缺失疫苗的出现,一些发达国家通过免疫及淘汰带毒猪,已在家猪中成功实现了伪狂犬病净化。本文结合近年来的调查和研究资料,对猪伪狂犬病的主要流行病学特征、在国内猪群中的流行概况、场间传播风险因素以及防控措施等进行了详细综述,为该病的防控和净化提出了建议。     

小反刍兽疫的防控

小反刍兽疫是由副小反刍兽疫病毒引起的山羊、绵羊、野生小反刍兽的高度接触传染性疾病,本文从兽医流行病学、诊断、防控等方面综述了该病的研究进展与最新的防控政策动态,为该病的研究和防控提供科学依据。     

我国1984-2014年羊口疮报道文献的统计分析

羊口疮是严重危害养羊业的病毒性疾病之一,回顾性数据对该病的综合防控具有重要意义。本文对1984-2014年报道的羊口疮文献进行了统计分析,对其年度流行病例数、地理分布、发病原因、诊断方法、预防治疗方案及病原学研究等数据进行了深入的分析,旨在为该病的综合防控提供回顾性和指导性数据,也为相关部门制定该病综合防控措施提供理论依据。     

猪场生物安全系统要点

建立生物安全体系是猪场防控疾病的前提,也是最经济有效的疫病防治措施。2018年我国发生非洲猪瘟以来,疫情对我国生猪养殖业带来深刻影响,在未来很长一段时间内该病都将是我国猪场的常态化疾病。非洲猪瘟疫情发生后,我国养猪业创新性地提出了系列生物安全防控技术,建立了能够有效应对疫情常态威胁的生物安全技术体系,两年多来的防控实践证明了这些生物安全防控手段的有效性。文章总结了猪场生物安全体系建设和管理中的关键环节及注意事项,希望可以为猪场非洲猪瘟防控提供参考。     

我国鸭疫里氏杆菌病流行概述

鸭疫里氏杆菌因其血清型多且复杂,抗药性严重,其已成为危害我国养鸭业的一种主要疾病。为进一步提高对鸭疫里氏杆菌病的防控水平,论文就该病的流行病学、诊断方法及疫苗研制等方面的研究进展进行综述,以期为指导临床安全合理用药及制定综合防控措施提供参考。     

高致病性禽流感的流行特点以及防控手段

高致病性禽流感是一种较为常见的疾病,该病具有传播范围广,传染性强的特点,可严重影响我国家禽养殖业的健康发展,给养殖户带来巨大的经济损失.该病一年四季均可发生,但秋、春季发病率较高.因此,为降低该病的发病率,养殖人员必须熟练掌握该病的流行特点及防控措施.本文结合高致病性禽流感的流行特点、临床症状等,对该病的防控措施进行论...     

新城疫流行病学新特点及鹅新城疫防控策略

新城疫是危害我国养禽业最严重的疫病之一,与高致病性禽流感并列为世界公认的最重要的两个禽类疫病。该病为OIE规定的必须报告的疾病,也是我国规定的一类动物疫病,世界各国对新城疫的防治和研究一直十分重视。由于对该病采取的严格防控措施,包括扑杀、强制性免疫等,新城疫的爆发流行得到了一定的控制。自2005年5月以来,我国新城疫发生的频率、数量和规模总体在减少,但是我国每年仍然至少有一半以上的省市区有该病发生。     

The non-invasive and automated detection of bovine respiratory disease onset in receiver calves using infrared thermography

Bovine respiratory disease complex (BRD) causes considerable economic loss and biosecurity cost to the beef industry globally and also results in significant degradation to the welfare of affected animals. The successful treatment of this disease depends on the early, timely and cost effective identification of affected animals. The objective of the present study was to investigate the use of an automated, RFID driven, noninvasive infrared thermography technology to determine BRD in cattle. Sixty-five calves averaging 220 kg were exposed to standard industry practices of transport and auction. The animals were monitored for BRD using conventional biometric signs for clinical scores, core temperatures, haematology, serum cortisol and infrared thermal values over 3 weeks. The data collected demonstrated that true positive animals for BRD based on a gold standard including core temperature, clinical score, white blood cell number and neutrophil/lymphocyte ratio displayed higher peak infrared thermal values of 35.7±0.35 °C compared to true negative animals 34.9±0.22 °C (P<0.01). The study also demonstrated that such biometric data can be non-invasively and automatically collected based on a system developed around the animal's water station. It is concluded that the deployment of such systems in the cattle industry would aid animal managers and practitioners in the identification and management of BRD in cattle populations.     

The epidemiology of bovine respiratory disease: What is the evidence for predisposing factors?

Bovine respiratory disease (BRD) is the most costly disease of beef cattle in North America. It is multi-factorial, with a variety of physical and physiological stressors combining to predispose cattle to pneumonia. However, efforts to discern which factors are most important have frequently failed to establish definitive answers. Calves are at highest risk shortly after transport. Risk factors include purchasing from sale barns and commingling. It is unclear whether or not these practices increase susceptibility, increase exposure, or are proxies for poor management. Lighter-weight calves appear to be at greater risk, although this has not been consistent. Persistent infection (PI) with bovine virus diarrhea virus increases BRD occurrence, but it is unclear if PI calves affect other cattle in the feedlot. The complexity of BRD has made it difficult to define involvement of individual factors. Stressors may play a role as "necessary but not sufficient" components, requiring additive effects to cause disease.     

Evaluation of practices used to reduce the incidence of bovine respiratory disease in Australian feedlots (to November 2021)

Bovine respiratory disease (BRD) has been identified as the most significant infectious disease of feedlot cattle in eastern Australia.¹ Bovine respiratory disease causes economic loss due to medication costs, mortalities, excessive feed inputs associated with increased time on feed, reduced sale prices and associated labour costs. Bovine respiratory disease is a complex multifactorial condition with multiple animal, environmental and management risk factors predisposing cattle to illness. A range of microorganisms are implicated in BRD with at least four viral and five bacterial species commonly involved individually or in combination. The viruses most commonly associated with BRD in Australia are bovine herpesvirus 1 (BHV1), bovine viral diarrhoea virus (BVDV or bovine pestivirus), bovine parainfluenza 3 virus (PI3) and bovine respiratory syncytial virus (BRSV). More recently, bovine coronavirus has been identified as a potential viral contributor to BRD in Australia.² A number of bacterial species have also been recognised as important to the BRD complex; these include Mannheimia haemolytica, Pasteurella multocida, Histophilus somni, Trueperella pyogenes and Mycoplasma bovis. Although one or more of the pathogens listed above can be isolated from clinical cases of BRD, there is no evidence that infection alone causes serious illness. This indicates that, in addition to specific infectious agents, other factors are crucial for the development of BRD under field conditions. These can be categorised as environmental, animal and management risk factors. These risk factors are likely to exert their effects through multiple pathways including reductions in systemic and possibly local immunity. For example, stressors such as weaning, handling at saleyards, transport, dehydration, weather conditions, dietary changes, comingling and pen competition might reduce the effectiveness of the immune system. Reduced immunocompetence can allow opportunistic infection of the lower airways with potential pathogens leading to the development of BRD. The objective of this paper is to critically review the evidence for management practices aimed at reducing the incidence of BRD in Australian feedlot cattle. Predisposing factors (Table 1) largely beyond the control of most feedlots, such as weather and exposure to respiratory viruses, are discussed separately, but these factors can generate indirect prevention responses that are discussed under the preventative practices categories. The current practices are classified as either animal preparation practices (Table 2) or feedlot management practices (Table 3).     

Galyean Appreciation Club Review: revisiting nutrition and health of newly received cattle—what have we learned in the last 15 years?

Our objective was to review the literature related to the health and management of newly received cattle published since a previous review by Duff and Galyean (2007). Bovine respiratory disease (BRD) continues to be a major challenge for the beef industry. Depending on disease severity, animals treated for BRD have decreased performance and lowered carcass value. Diagnosis of BRD is less effective than desired, and progress on developing real-time, chute-side methods to diagnose BRD has been limited. Systems that combine lung auscultation with temperature and body weight data show promise. Assessment of blood metabolites and behavior monitoring offer potential for early identification of morbid animals. Vaccination and metaphylaxis continue to be important tools for the prevention and control of BRD, but antimicrobial resistance is a concern with antibiotic use. Dietary energy concentration and roughage source and level continue to be important topics. Mineral supplementation has received considerable attention, particularly the use of organic vs. inorganic sources and injectable minerals or drenches given on arrival. The use of probiotics and prebiotics for newly received cattle has shown variable results, but further research is warranted. The health and nutrition of newly received cattle will continue to be an important research area in the years to come.     

Associations between weather conditions during the first 45 days after feedlot arrival and daily respiratory disease risks in autumn-placed feeder cattle in the United States

Data on associations between weather conditions and bovine respiratory disease (BRD) morbidity in autumn-placed feedlot cattle are sparse. The goal of our study was to quantify how different weather variables during corresponding lag periods (considering up to 7 d before the day of disease measure) were associated with daily BRD incidence during the first 45 d of the feeding period based on a post hoc analysis of existing feedlot operational data. Our study population included 1,904 cohorts of feeder cattle (representing 288,388 total cattle) that arrived to 9 US commercial feedlots during September to November in 2005 to 2007. There were 24,947 total cases of initial respiratory disease (animals diagnosed by the feedlots with BRD and subsequently treated with an antimicrobial). The mean number of BRD cases during the study period (the first 45 d after arrival) was 0.3 cases per day per cohort (range = 0 to 53.0), and cumulative BRD incidence risks ranged from 0 to 36% within cattle cohorts. Data were analyzed with a multivariable mixed-effects binomial regression model. Results indicate that several weather factors (maximum wind speed, mean wind chill temperature, and temperature change in different lag periods) were significantly (P < 0.05) associated with increased daily BRD incidence, but their effects depended on several cattle demographic factors (month of arrival, BRD risk code, BW class, and cohort size). In addition, month and year of arrival, sex of the cohort, days on feed, mean BW of the cohort at entry, predicted BRD risk designation of the cohort (high or low risk), cohort size, and the interaction between BRD risk code and arrival year were significantly (P < 0.05) associated with daily BRD incidence. Our results demonstrate that weather conditions are significantly associated with BRD risk in populations of feedlot cattle. Defining these conditions for specific cattle populations may enable cattle health managers to predict and potentially manage these effects more effectively; further, estimates of effects may contribute to the development of quantitative predictive models for this important disease syndrome.     

主要病毒性牛呼吸道疾病的研究进展

牛呼吸道疾病（bovine respiratory disease,BRD）是引起舍饲牛发病和死亡的主要原因,给北美和世界养牛业造成巨大的经济损失。BRD是由多种病毒、细菌与外界环境相互作用,如应激、环境因素与多种病毒、细菌和支原体等而引起的一种严重的呼吸系统疾病。作者就引起BRD的常见和严重的病原牛传染性鼻气管炎病毒（infectious bovine rhinotracheitis virus,IBRV）和牛呼吸道合胞体病毒（bovine respiratory syncytial virus,BRSV）的生物学特性、细胞感染和致病机制等进行简要概述,以期为该病的防制和研究提供参考。     

Microbiological and histopathological findings in cases of fatal bovine respiratory disease of feedlot cattle in Western Canada

The aim of this study was to describe the microbiologic agents and pathologic processes in fatal bovine respiratory disease (BRD) of feedlot cattle and to investigate associations between agents and pathologic processes. Ninety feedlot calves diagnosed at necropsy with BRD and 9 control calves without BRD were examined, using immunohistochemical (IHC) staining and histopathologic studies. Mannheimia haemolytica (MH) (peracute, acute, and subacute cases) and Mycoplasma bovis (MB) (subacute, bronchiolar, and chronic cases) were the most common agents identified in fatal BRD cases. Significant associations (P < 0.10) were detected between microbiologic agents and between agents and pathologic processes. When IHC staining was used, 25/26 (96%) of animals that were positive for bovine viral diarrhea virus (BVDV) were also positive for MH; 12/15 (80 %) of animals that were positive for Histophilus somni (HS) were also positive for MB; and all of the animals that were positive for HS were negative for MH and BVDV. This quantitative pathological study demonstrates that several etiologic agents and pathologic processes are involved in fatal BRD of feedlot cattle.     

Bovine respiratory disease in feedlot cattle: phenotypic, environmental, and genetic correlations with growth, carcass, and longissimus muscle palatability traits

Bovine respiratory disease (BRD) is the most costly feedlot disease in the United States. Selection for disease resistance is one of several possible interventions to prevent or reduce the economic loss associated with animal disease and to improve animal welfare. Undesirable genetic relationships, however, may exist between production and disease resistance traits. The objectives of this study were to estimate the phenotypic, environmental, and genetic correlations of BRD with growth, carcass, and LM palatability traits. Health records on 18,112 feedlot cattle over a 15-yr period and slaughter data on 1,627 steers over a 4-yr period were analyzed with bivariate animal models. Traits included ADG, adjusted carcass fat thickness at the 12th rib, marbling score, LM area, weight of retail cuts, weight of fat trim, bone weight, Warner-Bratzler shear force, tenderness score, and juiciness score. The estimated heritability of BRD incidence was 0.08 +/- 0.01. Phenotypic, environmental, and genetic correlations of the observed traits with BRD ranged from -0.35 to 0.40, -0.36 to 0.55, and -0.42 to 0.20, respectively. Most correlations were low or negligible. The percentage of carcass bone had moderate genetic, phenotypic, and environmental correlations with BRD (-0.42, -0.35, and -0.36, respectively). Hot carcass weight and weight of retail cuts had moderate, undesirable phenotypic correlations with BRD (0.37 and 0.40, respectively). Correlations of BRD with LM palatability and ADG were not detected. Low or near zero estimates of genetic correlations infer that selection to reduce BRD in feedlot cattle would have negligible correlated responses on growth, carcass, and meat palatability traits or that selection for those traits will have little effect on BRD susceptibility or resistance.     

Undifferentiated bovine respiratory disease (shipping fever): Is it communicable?

A study was conducted on 6–8-month old calves entering 2-research facility feedlots in 1983–1985, to examine if the occurrence of undifferentiated bovine respiratory disease (BRD) clustered within pens. For the purposes of analysis, 12 different groups of cattle were formed based on the source of cattle within year and/or year of arrival.The morbidity rates of BRD ranged from 5.7 to 64% and varied significantly from group to group (i.e., source to source) within year and from year to year. In all groups except one, the secondary attack (morbidity) rates were lower than the morbidity rates.An algorithm to examine for extra-binomial variation was used to formally examine for pen effects (clustering of disease within pen). In all models, a simple binomial model was sufficient to describe the data, i.e., the usual binomial parameter was estimated to describe the mean level of BRD by group, no additional parameter estimates were required to describe pen effects within group.Thus, although BRD has important pathogens as part of its sufficient causes, there is no evidence that clinical disease in one individual increases the risk of disease for other cattle in the same pen.     

Effects of 3-methylindole production and immunity against bovine respiratory syncytial virus on development of respiratory tract disease and rate of gain of feedlot cattle

OBJECTIVE: To determine whether immunity against bovine respiratory syncytial virus (BRSV) mitigates the effects of 3-methylindole (3MI) on occurrence of bovine respiratory tract disease (BRD) and rate of gain in feedlot cattle. ANIMALS: 254 mixed-breed beef cattle. PROCEDURE: Cattle were randomly assigned to 1 of 3 groups at the time of arrival at the feedlot. One group was vaccinated with an inactivated BRSV vaccine, another was vaccinated with a modified-live BRSV vaccine, and the third was maintained as unvaccinated control cattle. On days 0 and 28, serum BRSV antibody concentrations were measured, using serum neutralizing and ELISA techniques. Serum 3MI concentrations were measured at feedlot arrival and 3 days later. Cattle were monitored for development of BRD. At slaughter, lungs were evaluated grossly for chronic lesions. RESULTS: Higher serum 3MI concentrations early in the feeding period were associated with lower mean daily gain. Control cattle were more likely to be treated for BRD after day 3, compared with cattle vaccinated with the modified-live BRSV vaccine. Humoral immunity against BRSV did not appear to modify the effect of 3MI on development of BRD or mean daily gain. CONCLUSIONS AND CLINICAL RELEVANCE: Results suggest that abrogating the effects of 3MI and BRSV infection may improve the health and growth performance of feedlot cattle. However, in this study, immunity against BRSV did not appear to protect against the potential synergism between 3MI and BRSV infection, possibly because of the slow rates of gain of cattle included in the study or timing of sample collection.