Epidemiology and control of brucellosis in China

The paper describes the history and evolvement of brucellosis in China. It presents the variation of epidemic situation, epidemiological characteristics, application of vaccines and control in brief. Before 1980s, human and animal brucellosis was quite severe; during 1980s, the incidence of human and animal brucellosis was relatively low, and seemed to decrease during the decade. During 1990s, there were no obvious changes in the incidence of animal brucellosis, but the incidence of human brucellosis increased, especially from 1995 to 2001. There are not only some common characteristics but also some differences in brucellosis epidemiology relative to that reported in the rest of the world. For the entire country, B. melitensis was the predominant strain associated with outbreaks, and the epidemic peak is from February to June. Several Brucella vaccines have been used in China for prevention and control of brucellosis. such as B. abortus 104 M in humans, B. suis S2 in animals. The introduction of comprehensive measures has allowed great progress in the prevention and control of brucellosis in China. Surveillance points were set-up countrywide to estimate the epidemic situation. In addition, we discussed the new characteristics of brucellosis in China, the influence of the El Nino phenomenon on brucellosis epidemic situation, the phenomenon of antigenic interference between Brucella species and some disadvantages of live Brucella vaccines.     

Effect of simulated transport stress on the rat small intestine: A morphological and gene expression study

The present study investigated the effects of simulated transport stress on morphology and gene expression in the small intestine of laboratory rats. Sprague Dawley rats were subjected to 35 °C and 0.1×g on a constant temperature shaker for physiological, biochemical, morphological and microarray analysis before and after treatment. The treatment induced obvious stress responses with significant decreases in body weight (P < 0.01), increases in rectal temperature, serum corticosterone (CORT), serum glucose (GLU), creatine kinase (CK) and lactate dehydrogenase (LDH) levels (P < 0.01), as well as expression of Hsp27/70/90 mRNA (P < 0.05; P < 0.01). The rat jejunum was severely damaged and apoptotic after mimicking transport stress, which may mainly be related to cell death, oxidation reduction and hormone imbalance determined by microarray analysis. The bioinformatics analysis from the present study would provide insight into the potential mechanisms underlying transport stress-induced injury in the rat small intestine.     

法氏囊活性肽对鸡体增重及饲料转化率的影响

把不同剂量的法氏囊活性肽 (BS)冻干粉与传染性法氏囊病 (IBD)活苗混合后 ,对 2 1日龄SPF鸡滴鼻点眼 ,同时另选一批同样生长状态的鸡 ,在颈部皮下接种IBD细胞毒油苗 ,同时肌肉注射上述不同剂量法氏囊活性肽 ,观察法氏囊活性肽对鸡生长性能的影响。结果发现 :免疫后7d ,活苗 0 2mLBS组增长最快 ,比免疫对照组多增 82 5 % ,并且饲料报酬高。但从整个试验期看 ,0 4mLBS组增重效果较好 ,比免疫对照组多增 1 9 8% ,并且有较高的饲料转化率。而肌肉注射BS组中 ,高剂量 (0 8mL)BS组的增重效果一直很好 ,比对照组总增重平均多增 7 2 3 % ,并有较高的饲料报酬。这说明滴鼻点眼或是肌肉注射 ,BS都有促生长的作用     

药物代谢动力学猪链球菌病模型的研制

为研制适于猪的药物代谢动力学研究的传染病模型，取长白×杜洛克杂种猪１６头（体重３２．０±０．７ｋｇ），每猪皮下接种纯净猪链球菌（Ｃ７４－４１型）１２．５亿个活菌，复制出典型的亚急性型猪链球菌病。动物经感染后１ｄ体温持续升高１．５～２．０℃。血浆总蛋白含量开始持续降低（Ｐ＜０．０１），血清肌酐浓度则开始升高（Ｐ＜０．０５）。感染后２．５ｄ，磺溴酞的消除半衰期和给药后１５ｍｉｎ的滞留率均下降（Ｐ＜０．     

The production of short chain fatty acid and colonic development in weaning piglets

Weaning process widely affects the small intestinal structure and function in piglets, while the responses of large intestine to weaning stress are still obscure. The purpose of this study was to determine the developmental changes (i.e., short chain fatty acids (SCFAs) concentrations, growth parameters, crypt‐related indices and antioxidant capacity) in colon of piglet during weaning. Forty piglets were weaned at day 21 and euthanized to collect colonic tissues and digesta samples on day 0, 1, 3, 7 and 14 post‐weaning (n = 8). Piglet growth performance was improved (p < .001) on day 7 and 14 post‐weaning. The concentrations of acetate, propionate, butyrate, valerate, isobutyrate, isovalerate and total SCFAs were higher (p < .001) during the late post‐weaning period. The mRNA abundances of SCFAs transporters were greater (p < .001) on day 7 and 14. The absolute and relative weights, absolute length and perimeter of colon were greater (p < .001) on day 7 and 14. Similarly, post‐weaning increases (p < .001) in colonic crypt depth and Ki67 positive cells numbers per crypt were observed during the same period. Colonic crypt fission indices decreased (p < .01), while total crypt numbers increased (p < .001) on day 14 after weaning. Moreover, total SCFAs concentration was significantly associated with colonic growth parameters and Ki67 cells/crypt (p < .001). In addition, catalase content was decreased on day 3, 7, and 14, whereas, the concentrations of total superoxide dismutase (T‐SOD) and manganese‐containing superoxide dismutase (MnSOD) were higher (p < .05) on day 1 and 3 post‐weaning. These results showed that weaning process has a significant effect on colonic growth and development, which might be associated with the change of SCFAs concentrations in colon.     

宁夏首起牛结节性皮肤病疫情流行病学调查

2020年10月,宁夏盐池县、利通区、平罗县发生输入性牛结节性皮肤病疫情。为查明疫情发生原因,分析疫情扩散风险,宁夏回族自治区农业农村厅畜牧兽医局组织成立督导组进行流行病学调查。通过现场调查、座谈及实验室检测,综合发病、溯源和追踪情况以及实验室检测结果,分析认为此次疫情是由调入纯种荷斯坦育成奶牛引起的。因及时采取了封锁疫点、控制移动、扑杀、无害化处理、清洗消毒、杀灭蚊蝇、免疫等综合处置措施,疫情扩散风险较低。此次疫情警示,要强化牛只及其产品的调运监管,加强疫情排查监测,及时发现和处置疫情。     

Rapid identification and differentiation of Theileria sergenti and Theileria sinensis using a loop-mediated isothermal amplification (LAMP) assay

The present study developed and validated a species-specific loop-mediated isothermal amplification (LAMP) assay for the rapid detection and discrimination of two benign bovine Theileria species – T. sergenti and T. sinensis. The LAMP assay is inexpensive and easy to perform and involves a rapid reaction-the amplification can be performed in 55 min or 50 min under isothermal conditions of 61 °C or 63 °C, respectively, by employing a set of four species-specific primer mixtures. The results can be checked using agarose gels. The optimal assay conditions, under which the assay exhibited with no cross-reaction with other closely related tick-borne parasites (T. annulata, Babesia bovis, B. bigemina, B. major, B. ovata, B. U. sp., Anaplasma marginale) or between the two Theileria species of interest, was established. The assay is approximately 10-fold more sensitive than the conventional specific PCR assay. The LAMP assay was validated using DNA from 6 standard stocks in the laboratory and was evaluated for its diagnostic utility using blood samples collected from experimentally and naturally infection cattle or yaks in China. These findings indicate that this Theileria species-specific LAMP assay may have potential clinical applications for the detection and differentiation of two benign bovine Theileria species – T. sergenti and T. sinensis, especially in endemic countries.     

Mechanisms Involved in the Growth Promotion of Weaned Piglets by High-level Zinc Oxide

Dietary supplementation with high levels of zinc oxide (ZnO) is an effective method to prevent diarrhea and promote growth in weaned piglets. However, the mechanisms behind these beneficial effects are not well understood. Recent advances in this field indicated that the effects of ZnO on piglet growth are achieved through multiple regulatory pathways rather than a single pathway. This review focuses on recent advances in the effects of high level ZnO on:1) Zn status in weaned piglets;2) intestinal microbe flora regulation;3)intestinal structure and function;4 )ion secretion in the intestine epithelium;5) intestinal immunology; and 6) secretion of brain-intestine peptides. ZnO appears to regulate the intestinal microflora and decreases the release of histamine to prevent diarrhea. ZnO also increases the expression of intestinal insulin-like growth factor-1 (IGF-1) and the IGF-1 receptor to ameliorate intestinal injury associated with weaning, and mediates secretion of brain-gut peptides to stimulate food intake, to promote the growth of piglets. Better understanding of the underlying mechanisms should inspire us to supplement the diet for weaned piglets with ZnO and investigate new approaches to prevent diarrhea and enhance growth.     

冷却塔中新型混流式水轮机设计

通过数值模拟和试验两种方法,开发出一种新型高比转速混流式水轮机,配备相应变比的减速器,代替冷却塔中的风扇电动机,以达到节能的目的.根据冷却塔水轮机工作环境的特点,为尽量减小水轮机尺寸,在结构设计方面提出了金属梯形蜗壳和单列环形导叶.通过数值模拟,分析了不同的导叶形式、转速、叶片安放角对水轮机性能的影响.通过对比,选取负曲度导叶形式,选择最优单位转速及叶片安放角,确定最优性能的水轮机数模方案.通过物模试验证明所开发的高比转速混流式节能水轮机尺寸能够满足冷却塔要求,其效率高,性能稳定,可以在有条件的地方推广应用.     

基于遗传算法的农业机械中行星传动机构的优化设计

行星传动机构在水稻插秧机分插机构、拖拉机变速箱、秸秆压块机等渚多农业机械中得到了应用.如何优化设计行星传动结构,以便更好地适应农业机械生产需求,是一项极为重要的工作.为此,介绍了行星传动结构优化设计模型和基本遗传算法的基本原理,在此基础上,将星齿行星传动的最小体积作为优化设计目标,采用遗传算法进行优化设计.实验结果表明,此方法有效减少了星齿行星传动体积,更好地适应了农业机械对于成本和体积的特殊需求.