Oral vaccination of brushtail possums with BCG: Investigation into factors that may influence vaccine efficacy and determination of duration of protection

AIMS: To determine factors that may influence the efficacy of an oral pelleted vaccine containing Mycobacterium bovis bacille Calmette-Guérin (BCG) to induce protection of brushtail possums against tuberculosis. To determine the duration of protective immunity following oral administration of BCG.

METHODS: In Study 1, a group of possums (n=7) was immunised by feeding 10 pellets containing dead Pasteur BCG, followed 15 weeks later with a single pellet of live Pasteur BCG. At that time, four other groups of possums (n=7 per group) were given a single pellet of live Pasteur BCG orally, a single pellet of live Danish BCG orally, 10 pellets of live Pasteur BCG orally, or a subcutaneous injection of live Pasteur BCG. For the oral pelleted vaccines, BCG was formulated into a lipid matrix, and each pellet contained approximately 10⁷ colony forming units (cfu) of BCG, while the vaccine injected subcutaneously contained 10⁶ cfu of BCG. A sixth, non-vaccinated, group (n=7) served as a control. All possums were challenged by the aerosol route with a low dose of virulent M. bovis 7 weeks after vaccination, and killed 7–8 weeks after challenge. Protection against challenge with M. bovis was assessed from pathological and bacteriological findings.

In Study 2, lipid-formulated live Danish BCG was administered orally to three groups of possums (10–11 per group), and these possums were challenged with virulent M. bovis 8, 29 or 54 weeks later. The possums were killed 7 weeks after challenge, to assess protection in comparison to a non-vaccinated group.

RESULTS: The results from Study 1 showed that vaccine efficacy was not adversely affected by feeding dead BCG prior to live BCG. Feeding 10 vaccine pellets induced a level of protection similar to feeding a single pellet. Protection was similar when feeding possums a single pellet containing the Pasteur or Danish strains of BCG. All vaccinated groups had significantly reduced pathological changes or bacterial counts when compared to the non-vaccinated group. In Study 2, oral administration of Danish BCG induced protection against challenge with M. bovis, which persisted for at least 54 weeks after vaccination. Some protection was observed in possums challenged 54 weeks after vaccination, but this protection was significantly less than that observed in groups vaccinated 29 or 8 weeks prior to challenge. There was a strong relationship between the proportion of animals producing positive lymphocyte proliferation responses to M. bovis antigens and protection against challenge with M. bovis.

CONCLUSIONS: Factors considered potentially capable of interfering with vaccination, including feeding dead BCG to possums prior to feeding live BCG, feeding multiple doses of BCG at one time, and changing strains of BCG, were shown not to interfere with the acquisition of protective immune responses in possums. Protection against tuberculosis was undiminished up to 29 weeks after vaccination with BCG administered orally. It is concluded that vaccination of possums by feeding pellets containing BCG is a robust and efficient approach to enhance the resistance of these animals to tuberculosis.     

Selective and on-demand drenching of lambs: Impact on parasite populations and performance of lambs

AIM: To determine whether drenching regimes for lambs by which a proportion (10%) of the heaviest animals was selectively left untreated, or animals are only drenched ‘on demand’ when faecal nematode egg counts (FEC) exceeded a threshold level, would result in measurable increases in parasite larval challenge in the autumn and/or decreases in the performance of lambs.

METHODS: A replicated study compared three drenching strategies in which mobs of lambs (n=360 in total) received either: a five-drench preventive programme, administered to all animals (Treatment 1); a five-drench preventive programme, but the 10% heaviest animals left untreated each time (Treatment 2); or drench treatments administered only when FEC exceeded 500 eggs per gram of faeces (epg) (Treatment 3). After the five-drench programme, animals in Treatments 1 and 2 were treated according to FEC as for Treatment 3. A triple-combination drench containing ivermectin, oxfendazole and levamisole, administered orally, was used for all treatments. There were nine farmlets, allowing three replicates of each treatment, in a completely randomised design. Parasite infestations on pasture were measured in autumn by pasture plucks, and worm burdens were monitored in tracer lambs, while the performance of lambs was assessed by liveweight gains, fleece weights, and body condition and dag scores.

RESULTS: Increased numbers of Haemonchus contortus and Trichostrongylus colubriformis larvae on pasture were found in the autumn on farmlets treating selectively or on-demand (Treatments 2 and 3). No differences were detected in other parasite species. Mean liveweight gains did not differ between treatments but some differences were detected between drenched and undrenched lambs in Treatment 2. Mean body condition and mean dag scores of lambs in Treatment 3 tended to be lower and higher, respectively, than those of lambs in Treatment 1; Treatment 2 was generally intermediate.

CONCLUSIONS: Drenching strategies for lambs designed to slow the development of anthelmintic resistance, by increasing the pool of susceptible worms available to dilute resistant survivors after treatment, resulted in increased numbers of H. contortus and T. colubriformis but not other species of parasite on pasture. The increased parasite challenge to lambs in the autumn was associated with small production losses, which may be acceptable to farmers wishing to implement such strategies. It is clear that further work is required on the interaction between management practices and the population dynamics of parasites, especially with regard to creating pools of susceptible genotypes to slow the development of drench resistance.     

青贮对天然草原牧草长链脂肪酸的影响

以呼伦贝尔草原四种不同草地类型牧草为研究对象,分别对其进行单贮、混贮处理,研究不同青贮处理对不同草地类型牧草长链脂肪酸的构成及含量的影响.结果表明:四种草地类型不同处理样品所含长链脂肪酸的成分相同,都以亚麻酸和棕榈酸为主,亚油酸含量也比较高;四种草地类型不同处理间各长链脂肪酸的含量均有所差异,混贮处理对各长链脂肪酸含量变化的影响最大.混贮处理后贝加尔针茅硬脂酸(P＜0.01)、亚油酸(P＜0.05)的含量明显升高,油酸明显下降(P＜0.05);四种草地经不同处理后同一草地类型取样点之间长链脂肪酸含量的差异不大.     

内蒙古自治区区域协调问题与对策研究

内蒙古自治区与相关区域构成了一个复杂、开放的区域系统,其内部主要由自然区、行政区、主体功能区等组成;区域协调内容包括内蒙古自治区与全国的协调、内蒙古自治区东部与西部的协调、呼和浩特、包头、鄂尔多斯(简称呼包鄂,下同)三市协调、内蒙古自治区与俄罗斯等国家的协调、内蒙古自治区与相关省市自治区的协调、自然区与行政区的协调、行政区与主体功能区的协调、城市与农牧区的协调等;存在着许多社会经济指标低于全国平均水平、东部与西部社会经济等方面差距过大、出口依存度太低与外贸逆差过大、与相关省市自治区自然资源及产业的互补性差、地方利益与流域全局利益矛盾尖锐、主体功能区跨界缺乏统一领导、呼包鄂三市产业同构化现象趋于明显、城乡差距过大等问题;应该采取加强内蒙古自治区区域协调研究、编制区域协调规划、建立区域协调组织、利用调控手段促进区域协调发展和构建区域协调内在机制等对策.     

水稻生产机械专利技术分析

在水稻生产机械的产业化中,相关的知识产权问题乃是众多法律问题中的基础性问题,而所进行的与水稻生产机械相关的专利权检索则为黑龙江省制定相应的知识产权战略提供了基础性数据,使最终的战略制定更为科学。在对相应检索范围进行框定,检索数据进行筛选、整理与分析的基础上,得出相应的科学结论,并从如何提高黑龙江省专利申请水平、加强各方主体的职能与合作、保护农民权益等角度提出了建议。     

Neuroanatomy of the equine dorsal cricoarytenoid muscle: surgical implications

Reason for performing study: Studies are required to define more accurately and completely the neuroanatomy of the equine dorsal cricoarytenoid muscle as a prerequisite for developing a neuroprosthesis for recurrent laryngeal neuropathy. Objective: To describe the anatomy, innervation, fibre types and function of the equine dorsal cricoarytenoid muscle. Methods: Thirty‐one larynges were collected at necropsy from horses with no history of upper airway disease and 25 subjected to gross dissection. Thereafter, the following preparations were made on a subset of larynges: histochemical staining (n = 5), Sihler's and acetylcholinesterase staining for motor endplates (n = 2). An additional 6 larynges were collected and used for a muscle stimulation study. Results: Two neuromuscular compartments (NMC), each innervated by a primary nerve branch of the recurrent laryngeal nerve, were identified in all larynges. Stimulation of the lateral NMC produced more lateral displacement of the arytenoid cartilage than the medial NMC (P<0.05). The medial NMC tended to rotate the arytenoid cartilage dorsally. Motor endplates were identified at the junction of the middle and caudal thirds of each NMC. If fibre type grouping was present it was always present in both NMCs. Conclusions: The equine dorsal cricoarytenoid muscle has 2 distinct muscle NMCs with discrete innervation and lines of action. The lateral NMC appears to have a larger role in increasing cross‐sectional area of the rima glottidis. Potential relevance: This information should assist in planning surgical reinnervation procedures and development of a neuroprosthesis for recurrent laryngeal neuropathy.     

Impact of antimicrobial drug usage measures on the identification of heavy users, patterns of usage of the different antimicrobial classes and time-trends evolution

Several measurement units are available to quantify antimicrobial usage in veterinary medicine, to obtain diverse measures such as the weight of active substance used, the live weight (LW) treated, the fraction of animals exposed, the number of treatments recorded or the cost represented. These measures can be applied to study practices variability between farms, to characterize patterns of usage of the different antimicrobial classes or to follow evolution of antimicrobial usage with time. An investigation was carried out to specifically explore the influence of measurement units on the conclusions obtained from such studies. Antimicrobial exposure was explored in a sample of turkey and chicken broiler flocks, using six different units [kg of active compound, treatments, days of administration, kg of LW treated, animal daily dose to treat 1 kg of LW (ADD_kg) and euros] to compare flocks usage variability and patterns of use of the different antimicrobial classes. Time-trends evolutions of macrolides usage in turkey broilers, characterized by percentage of flocks exposed and LW treated, were also compared. In all analyses, the measure gave different results without equivalences, highlighting the necessity for care in choosing the measurement unit and caution in interpreting the figures obtained.     

AMMI双标图在马铃薯区域试验产量分析中的应用

运用AMMI模型.结合双标图对2007年国家中晚熟西北组马铃薯品种区域试验各承试点的平均产量结果进行分析.试验结果表明,在参试品种中,L0031-17、青薯6号高产但不稳产,陇薯3号为高产稳产型,品种960102、中9931-48稳产但不高产,8025-1不稳产又不高产.AMMI模型具体、直观、有效的综合评价,为马铃薯品种提供了一种比较好的分析方法.     

马铃薯新品种青薯11号的选育

青薯11号是以同薯23号为母本,以青薯168为父本,通过有性杂交和系统选育育成的鲜食马铃薯新品种。中晚熟,出苗至收获107 d(天)左右;薯块椭圆形,粉红皮,薯肉黄色带红晕,芽眼浅;块茎淀粉含量17.96%,粗蛋白3.17%,VC240.3 mg·kg~(-1),还原糖0.279%。抗晚疫病。一般肥力条件下每667 m~2产量2 200~2 500 kg,高肥力条件下产量2 500~3 000kg。适宜在青海省各类地区种植。     

Echocardiographic variables in healthy North American Salukis

Introduction

To report normal echocardiographic variables from a population of healthy Salukis in North America.