采用SP法检测商品蛋鸡感染J亚群禽白血病病毒对产蛋性能的影响

本研究属世界上首次报道J亚群禽白血病病毒感染对蛋鸡产蛋性能的影响。尸体剖检观察到产蛋鸡的生殖系统发育不良，表现为卵巢、输卵管幼稚型，输卵管粗细不均。组织病理学观察，发现卵巢组织中有大量的胞浆内充满球形嗜酸性颗粒的骨髓瘤细胞。用特异性抗J亚群禽白血病病毒(ALV—J)囊膜糖蛋白gp85的单克隆抗体检测不产蛋鸡的卵巢、输卵管等待检的组织切片，均检出病毒阳性抗原。结果表明ALV—J的感染造成产蛋鸡卵巢、输卵管发育不良，是蛋鸡不产蛋的直接原因。     

动物性食品安全应从源头抓起

随着我国经济的发展和人民生活水平的提高,人们对动物性食品的需求发生了由量到质的变化,不仅仅关心动物性食品的营养价值,而且更加关注其卫生与安全。特别是近年来,国外重大动物疫病的发生,国内畜禽产品因抗生素残留在出口贸易中“屡遭封杀”,因兽药残留在国内引发一系列人体食物中毒事件等,更加重了国民对动物性食品安全和自身健康的担心。食品安全问题目前已成为我国各级政府和社会关注的热点问题,也是我国加入世贸组织之后畜牧业发展急需解决的重大问题。笔者认为,要想从根本上解决动物性食品安全问题,必须从动物性食品生产源头抓起,着…     

Multi‐channel visual evoked potential as an ancillary tool to diagnose intraorbital optic nerve lesions

Multi‐channel visual evoked potential (MVEP) recording method was used to assist in diagnosing a 4‐month‐old Chinese Albino rabbit with an intraorbital mass. Subcutaneous MVEP of its both eyes were recorded simultaneously using 16 electrodes (4 × 4) multi‐channel array. Analysis of the cortical potential landscapes (CPL) showed that the conduction function of right eye was remarkably impaired in terms of decreased amplitudes and prolonged latencies. Specific side‐dominant distribution asymmetry of the decreased MVEP amplitudes indicated that the temporal side of the optic nerve (ON) was severely involved. Overall prolonged latencies of the CPL without side differences suggested that the functional impairment could have been caused by the mechanical compression exerted by an intraorbital mass. Surgical removal procedures confirmed that the mass was located temporally to the ON. Pathological examination provided a final diagnosis of a giant polycystic mucocele. Beyond its significance as a standard tool to assess functional changes of the visual pathway, MVEP recordings might assist locating intraorbital lesions that involve the ON by careful analysis of abnormal CPLs.     

鱼类疫苗研究进展

经过试验探索、生产应用 ,鱼类疫苗的研究已进入用新技术和新方法研制高效疫苗的时期。疫苗的种类逐渐增多 ,除传统的死疫苗、活疫苗、化学疫苗以外 ,新型疫苗得到快速发展。主要包括 DNA疫苗、合成肽疫苗。一些疫苗已经成为工业化生产的商品用疫苗 ,如弧菌病疫苗、红嘴病疫苗、疖病疫苗、传染性造血器官坏死病疫苗。鱼类的免疫应答和疫苗的免疫接种方法等都会影响鱼类疫苗的应用。尽管鱼类疫苗面临着一些困难 ,但是它有广阔的发展前景     

Utilization of stereoisomers from alpha‐tocopherol in livestock animals

Alpha‐tocopherol derived from natural source is a single stereoisomer (i.e. RRR‐α‐tocopherol), whereas synthetic α‐tocopherol consists of a mixture of eight stereoisomers, including RRR‐, RRS‐, RSR‐, RSS‐α‐tocopherol (the 2R isomers, R configuration at positions 2′ of the phytyl tail) and SRR‐, SSR‐, SRS‐ and SSS‐α‐tocopherol (the 2S isomers, S configuration at positions 2′ of the phytyl tail). R and S are assigned by the sequence‐rule procedure, i.e. the priorities of the substituents decrease in clockwise direction or anti‐clockwise direction at each chiral centre. Not all these stereoisomers are equally bio‐available, which can be explained by the differences in the rate of degradation, transportation and retention. Humans and livestock animals can only utilize the 2R forms, while the 2S forms have very low bio‐availability or basically are not bio‐available. The utilization of 2R forms differs between different animal species. For humans and livestock animals, RRR‐α‐tocopherol has the highest bio‐availability compared with other stereoisomers, while other 2R forms have lower bio‐availability compared with RRR‐α‐tocopherol. The relative bio‐availability of RRR‐ and all‐rac‐α‐tocopherol is related to animal species, ages of animals and assessment criteria. In general, recent literature studies have demonstrated that the relative bioavailability of RRR‐ and all‐rac‐α‐tocopherol is 2:1, differing from the commonly used conversion factor of 1.36:1. The latter was based on rat‐resorption‐gestation test. Most recent studies have shown that this conversion factor of 1.36:1 is not applicable to livestock animals and based on other metabolic functions. When IU is required to express vitamin E activity, new conversion factors need to be defined for livestock animals. Quantitative determination of bio‐availability of the individual α‐tocopherol stereoisomers will give a more detailed picture of the bioavailability of natural and synthetic vitamin E forms.     

Effect of dietary methionine on growth performance and insulin‐like growth factor‐I mRNA expression of growing meat rabbits

An experiment was conducted to determine the effects of different amounts of dietary methionine on growth performance, serum protein, growth hormone (GH), insulin‐like growth factor‐I (IGF‐I) concentrations and IGF‐I mRNA expression of growing meat rabbits. One hundred weaned growing meat rabbits were allocated to individual cages and randomly divided into five groups. The methionine addition concentrations of the five groups were 0, 2, 4, 6 and 8 g/kg diet (as‐fed basis) and sulphur amino acids (SAA) concentrations ranging from 3.8 to 11.6 g/kg diet, respectively. The results obtained were as follows: the average daily gain of 2, 4 and 6 g/kg diet groups was higher than that of 0 g/kg diet group (p < 0.01). The feed gain ratio of the 4 g/kg diet group was lower than those of 0 and 8 g/kg diet group (p < 0.01). Methionine concentrations did not affect serum urea nitrogen, total protein, insulin and IGF‐I concentration (p > 0.05). The quadratic effects of methionine on the serum concentration of albumin (Alb) and GH were obtained (p = 0.013, p = 0.018). The quadratic effect of methionine amount on IGF‐I mRNA expression was obtained (p = 0.045). The serum concentration of Alb of the 4 g/kg diet group was higher than those of 0 and 8 g/kg diet group (p < 0.01). The serum concentration of GH of 8 g/kg diet group was higher than that of the 0 g/kg diet group (p < 0.05). The liver IGF‐I mRNA expression of 4 g/kg diet group was higher than those of the 0 and 8 g/kg diet group (p < 0.05). Providing a diet mainly consisted of corn, wheat bran and peanut vine, the optimum dietary methionine addition concentration and SAA concentration for a weaner to 2‐month‐old growing meat rabbits were shown to be 2 and 5.7 g/kg diet respectively.     

Biallele Expression of PEG10 Gene in Primordial Germ Cells Derived from Day 27 Porcine Fetuses

Primordial germ cells (PGCs) from day 27 porcine fetuses have often been isolated to establish pluripotent embryonic germ (EG) cell lines, but little is known regarding their imprinted gene status. In our study, we attempted to detect the imprinted gene expression of cloned embryos and EG cells derived from individual PGC of day 27 and day 35, using single nucleotide polymorphism (SNP) analysis of the paternally expression gene 10 (PEG10) as a sign of parental‐origin‐specific expression. The results showed biallelic gene expression of the SNP that occurred in EG cell colonies and almost all of the cloned blastocysts, demonstrating that aberrant imprinted gene expression of PEG10 occurs in the day 27 porcine PGCs, whereas monoallelic expression of the PEG10 gene occurs in all the PGC clones derived from day 35 PGCs. In addition, the same imprinted gene status was observed for blastocysts derived from both male and female PGCs, indicating that the parental genomic imprinting is erased in male and female germlines.     

绵羊BMP15基因B2突变可视化检测技术的建立

骨形态发生蛋白15（bone morphogenetic protein 15,BMP15）基因突变对绵羊排卵率、产仔数以及繁殖力有很大影响,本研究旨在建立快速可视化检测BMP15基因B2突变的技术。将改良的扩增阻滞突变系统（amplification refractory mutation system,ARMS）与核酸染料SYBR Green Ⅰ结合,针对BMP15基因B2突变设计ARMS特异性引物,使引物下游3'端的最后一个碱基为A,并在下游引物3'端的第3位碱基处设计额外的错配,以提高引物的特异性;经ARMS PCR扩增后,向产物中加入SYBR Green Ⅰ,通过肉眼观察PCR管内的颜色变化来检测BMP15基因的B2突变。经测序发现所采集的样本均为野生型,因此,利用重叠延伸PCR构建BMP15基因B2突变型模板,测序结果显示BMP15基因B2突变型模板构建成功。ARMS PCR结果显示,ARMS特异性引物能够只扩增突变型模板,而不会扩增野生型模板,且扩增效果良好。ARMS PCR扩增后加入SYBR Green Ⅰ发现已知野生型模板与阴性对照一致,呈SYBR Green Ⅰ原始颜色橙黄色,而已知突变型模板呈亮绿色,且色差明显,肉眼可辨。用建立的可视化检测BMP15基因B2突变的技术检测50个小尾寒羊基因组DNA （随机向其中20个样本中加入构建的BMP15基因B2突变型模板）,将可视化检测的突变型样本编号与混合样本时记录的编号对比,结果表明该技术能够准确检测绵羊BMP15基因的B2突变,且准确率高达100%。将构建的BMP15基因B2突变型的模板进行梯度稀释,对本试验可视化检测体系的灵敏度进行检测,发现ARMS可视化检测技术的灵敏度达到0.006 ng/μL。因此,本研究建立的技术能够可视化地检测绵羊BMP15基因B2突变,且准确率高,有望为高繁殖力绵羊的选育提供技术支持。     

饲料进出口贸易对我国经济增长的影响

我国是饲料生产加工大国,饲料生产量在世界上占据领先地位,饲料进出口贸易成交量较为庞大.在我国饲料进出口贸易中,近年来的贸易差有扩大趋势.这是由于我国长期在国外进口大量的饲料原料、粮食、产品导致的,另外,由于我国饲料出口贸易表现不够突出,对我国经济增长难以起到明显推动作用.本文从进出口贸易对经济的影响出发,通过分析我国饲...     

我国和欧盟兽药质量监督抽检工作机制对比研究

为更好地完善我国兽药质量监督抽检计划,通过对欧盟药品抽检管理工作机制的研究,本文分析了欧盟和我国兽药监督抽检管理方式的不同,从抽检责任部门、抽检目的、抽检计划内容、抽检计划制定流程、抽检品种的遴选和检测参数的确定等6方面进行了对比分析,探讨我国兽药质量监督抽检工作的管理中可以借鉴的方面。