口蹄疫病毒VP1基因密码子偏好性分析

VP1蛋白是口蹄疫病毒(FMDV)的主要结构蛋白,可诱导机体产生中和抗体以及激发保护性免疫应答。为探究VP1基因密码子偏好性,筛选出其最佳体外表达系统,使用Visual Gene Developer、CodonW、GraphPad Prism等软件,对VP1基因进行密码子偏好性分析,同时将VP1基因密码子使用频率与大肠杆菌、毕赤酵母、昆虫杆状病毒和哺乳动物细胞表达系统作了比较。结果显示,VP1基因的CAI为0.21,ENC为55.43,GC3S为65.26%,表明该基因密码子使用偏好较弱并且密码子偏好以G/C碱基结尾。结合VP1基因与各表达系统密码子使用频率比值,发现其与昆虫杆状病毒表达系统频率比值差异最小且CAI最大,因此推断昆虫杆状病毒表达系统是FMDV VP1基因最适体外表达系统。本研究为FMDV亚单位疫苗研制等提供了技术基础。     

雏鸭重组禽流感（H5+H7）三价灭活苗母源抗体消长规律

为探究雏鸭重组禽流感(H5+H7)三价灭活苗母源抗体消长规律,确定最佳首免日龄,将试验分为A组(种鸭免疫H5N1 Re-11+Re-12株、H7N9 H7-Re-2株、H5N2疫苗)和B组(种鸭免疫H5N2 rSD57株+rFJ56株、H7N9 rGD76株疫苗);选其孵化后的雏鸭各300羽,分别于1、7、14、21、28日龄时采血,每组随机采集100份样品,通过血凝(HA)和血凝抑制(HI)试验进行禽流感母源抗体检测。结果显示:两组各亚型母源抗体在1日龄时平均滴度均达最高水平( 7.27log2),且离散程度低( 0.22)。两组雏鸭的禽流感母源抗体阳性率均随日龄增长而逐渐下降,7日龄时,平均滴度在4.26log2以上,群体抗体阳性率在76%以上,其中B组阳性率略高于A组;14日龄时,平均滴度都下降到2.55log2以下,群体抗体阳性率下降到25%以下;21日龄时,平均滴度均在0.43log2以下,群体抗体阳性率下降至1%以下。结果表明,高抗体水平种鸭能够使后代雏鸭具有较高水平的禽流感母源抗体,但母源抗体保护时间较短,重组禽流感(H5+H7)三价灭活苗的最佳首免时间为7～14日龄。本研究为鸭禽流感疫苗免疫策略制定提供了参考。     

不同饲养条件对蝇蛆生长发育及蛹虫繁殖性能的影响

在不同饲养条件下饲养蝇蛆,从而建立蝇蛆养殖的最优环境组合量化标准.选择培养基基料中不同奶粉添加量、培养基湿度及饲养密度3个主要因素,每因素设4个水平,进行交叉组合试验,共有64个处理,每个处理设3个重复,观测每个组合条件下饲养蝇蛆的蛆重、蛆长、蛹重、蛹长等指标,以评价这些因素对蝇蛆生长发育及蛹虫繁殖性能的影响.单因素方差分析结果表明:不同奶粉添加量、培养基湿度及饲养密度对家蝇生长发育及繁殖性状等指标均存在极显著差异(P＜0.01),在奶粉添加量为6 g、培养基含水量为65％～80％、饲养密度为每瓶60～90条时最有利于家蝇生长发育及蛹虫的繁殖.此外,三因素之间对生长性状蛆重和蛆长存在极显著差异(P＜0.01),但在化蛹率指标中表现为任意两因素的交互作用有极显著差异(P＜0.01),而三因素交互却不显著(P＞0.05);繁殖性状蛹重和化蛹率指标的三因素互作效应显著(P＜0.05),而对家蝇蛹长的互作效应不显著(P＞0.05).结果 显示,家蝇幼虫的饲养条件以30 g发酵麦麸+3g红糖的基础培养基中,添加奶粉量为6 g,培养基湿度为80％,饲养密度为60～ 90条/瓶时,生长性状中蛆重、蛆长、化蛹率和繁殖性状中蛹重、蛹长等指标均较为理想;而培养基湿度为50％时,羽化率最高,且随着培养基湿度的增大,羽化率呈下降趋势.     

关于天津市非洲猪瘟无疫小区创建工作的思考

2019年12月,农业农村部组织制定颁发了《无规定动物疫病小区评估管理办法》（农业农村部公告第242号）、《农业农村部办公厅关于印发<无非洲猪瘟区标准>和<无规定动物疫病小区管理技术规范>的通知》（农办牧[2019]86号）等文件,随即启动了非洲猪瘟无疫小区建设工作。     

A pioneering survey of deep-diving and off-shore cetaceans in the northern South China Sea

A pioneering boat-based survey was conducted in 2019, to gather baseline information regarding the presence, composition, relative abundance, and spatial distribution of deep-diving and off-shore cetaceans in the northern South China Sea (SCS). A total of 27 sightings comprising at least 8 cetacean species were recorded during the 13-day survey, including 5 deep-diving species (i.e. Risso's dolphin [Grampus griseus], short-finned pilot whale [Globicephala macrorhynchus], sperm whale [Physeter macrocephalus], Cuvier's beaked whale [Ziphius cavirostris], and an unidentified beaked whale [either the ginkgo-toothed beaked whale, Mesoplodon ginkgodens, or Deraniyagala's beaked whale, Mesoplodon hotaula]), as well as 3 off-shore dolphins (i.e. pantropical spotted dolphin [Stenella attenuate], striped dolphin [Stenella coeruleoalba], and Fraser's dolphin [Lagenodelphis hosei]). With the exception of pantropical spotted dolphins, all other species were sighted and recorded at sea in the northern SCS for the first time. The pantropical spotted dolphin was the most frequently sighted species, comprising 30% of the total sightings. Deep-diving cetaceans were mainly sighted in the northern Xisha Archipelago, whereas off-shore dolphins were distributed across the survey area. The pantropical spotted dolphin was observed in aggregations of more than 100 individuals and nearly all encountered species included calves; these findings suggested that the survey area functions as an important feeding and calving ground for various cetacean species. This pioneering survey provides fundamental information regarding cetacean fauna in the northern SCS and highlights the need to strengthen research and conservation efforts concerning these species.     

Green tea polyphenols supplementation alters immunometabolism and oxidative stress in dairy cows with hyperketonemia

Peripartal cows often experience negative energy balance, and are therefore prone to suffering from metabolic diseases such as hyperketonemia, which causes financial losses in dairy farms. This study aimed to investigate the effect of green tea polyphenol (GTP) supplementation during the periparturient period on production performance, oxidative stress and immunometabolism in dairy cows with hyperketonemia. One hundred Holstein cows were assigned to GTP (0.2 g/kg DM; n = 50) or control (without GTP; n = 50) group based on body weight, previous milk yield, and parity on d 15 before expected parturition. Subsequently, 10 cows with hyperketonemia were selected from each group, according to blood β-hydroxybutyric acid (BHBA) concentration between 1.2 and 2.9 mmol/L from 2 to 3 d postpartum. All cows were fed a close-up diet and a lactation diet with or without GTP supply from 15 d prepartum until 30 d postpartum. Milk and blood samples were obtained from 20 cows selected with hyperketonemia on 10, 20, and 30 d postpartum. Compared with control cows, greater milk yield and lower somatic cell count were observed in GTP cows. The GTP group had lower concentrations of BHBA, free fatty acids, cholesterol, triglyceride, reactive oxygen species, malondialdehyde, and hydrogen peroxide, greater concentrations of glucose, lower activities of aspartate aminotransferase, alanine aminotransferase, and glutamyl transpeptidase, alongside greater activities of superoxide dismutase, glutathione peroxidase, and total antioxidant capacity. Additionally, GTP supplementation up-regulated concentrations of interleukin-6 and interleukin-10, but down-regulated concentrations of tumor necrosis factor-α, interleukin-1β, interleukin-2, interleukin-8, and interferon-γ in plasma. Greater concentrations of plasma immunoglobulin G were also detected in the GTP group. Overall, the data suggested that GTP supplementation from 15 d prepartum to 30 d postpartum improved the milk yield and health status in cows with hyperketonemia during early lactation.     

彰武县东沟小流域综合治理及其效益分析

东沟小流域3年来的综合治理实践证明:根据辽北低山丘陵区风沙、干旱,水土流失严重的特点,进行详细的调查和科学的论证,因地制宜地布置各项水土保持措施,就能收到显著的保水保土效益和较高的经济效益。经统计,在近11km2的水土流失面积上,拦洪量达32.5万m3,拦沙量达到0.93万t。经济效益中的内部收益率为60.6%,经济效益费用比:3.85。     

豫西丘陵地区果牧结合立体生态园设计的探讨

根据豫西丘陵地区生态、经济、社会条件以及目前农牧业生产中存在的突出问题，提出果牧结合立体生态园建设是该地区生态农业发展的重要途径。并在调查和初步研究基础上设计了“畜（禽）—果”、“畜（禽）—沼—果”等果牧结合模式，分析了生态园建设研究中要探讨的具体内容。     

玉米变性淀粉气流干燥设备的设计

采用湿法工艺生产玉米变性淀粉时,湿淀粉通常采用气流干燥,根据用户需要,设计了一套负压气流干燥设备来满足玉米变性淀粉的干燥。文章介绍设备主要结构、工作原理,并对干燥必需的能耗、所需的风量和热量、干燥管的长度、引风机功率等参数进行计算。设备经过实际生产使用,能够满足玉米变性淀粉的干燥要求。