牛胚胎移植技术的产业化研究

本文探讨了引进国外优质奶、肉牛冷冻胚胎建立核心群，以及供体牛选择、超数排卵、胚胎冷冻保存和分割等相关技术，为牛胚胎移植产业化奠定基础。     

应用PCR-RFLP及PCR-SSCP技术检测猪RN基因的研究

RN(Rendement Napole)基因是影响猪肉肉质性状的一个主效基因，已被定位在猪的15号染色体上(15q25)，该基因在猪肉品质上存在严重的负面效应。应用限制性片段长度多态性(RFLP)和单链构象多态性(SSCP)分析技术快速检测猪RN基因，根据RN向200Q突变的原理设计引物，PCR扩增后得到一段长约577bp的片段，两种方法得到相同的结果。     

Identification of a novel Bacillus species isolated from Calculus Bovis

A novel Bacillus species of Calculus Bovis (cow gallstone) was isolated and identified in this study. Morphological features, bacterial fatty acid analysis using a microbial identification system, carbon source utilization profiles using Biolog system and 16S rDNA sequencing were employed to identify the isolated bacterium. This isolated bacterium was observed to be Gram‐negative, aerobic growing, rod‐shaped and short chain. The results of bacterial fatty acid analysis and physiological characteristics were not matched to the database. The main fatty acids found in the bacterium were 65.96% branched chain saturated fatty acids (iso C_11:0, anteiso C_11:0 and iso C_13:0～anteiso C_19:0). The bacterium oxidized 35 carbon sources and weakly responded with 49 of the 95 different carbon sources analyzed with the Biolog identification system. Based on 16S rDNA sequence analysis, this bacterium was classified as a novel Bacillus species.     

一起饲料未落实留样观察制度案的查处

2019年7月,A市农业综合执法支队执法人员在执法检查中发现,×宠物饲料有限公司涉嫌未落实留样观察制度而从事饲料生产。经立案调查,认定当事人违法事实存在,证据确凿。根据《饲料和饲料添加剂管理条例》规定,依法给予了行政处罚。本文重点介绍了案件的发生、查处经过、法律适用及处理情况等执法内容,讨论了饲料留样目的和意义、调查取证注意事项、违法物品的处理以及责令改正的正确适用等问题,指出了办理此类案件时的取证依据、处罚前置条件,以期为行政执法人员办理同类案件提供参考。     

脂肪酸调控奶牛乳腺microRNAs研究进展

脂类是一种可以为动物体储存和提供能量的物质,大量研究证实,日粮中脂类的改变可以改变microRNAs（miRNAs）的表达从而影响机体生命活动。本综述主要概括了脂肪酸对奶牛乳腺miRNAs的调控作用,从奶牛乳腺miRNAs表达特征、调控乳脂合成的miRNAs及外源添加脂肪酸对乳腺miRNAs的调控三个方面进行概述,旨在从转录后调控角度,建立营养物质与乳腺功能的联系,为未来相关研究提供参考。     

藏鸡NSTN基因克隆与mRNA组织表达谱分析

肌肉生长抑制素(MSTN)是骨骼肌发育的负性调控因子,本研究用RT-PCR方法克隆藏鸡MSTN编码基因,用半定量RT-PCR方法检测MSTN mRNA在藏鸡腿肌等10个组织的表达情况.结果显示,藏鸡MSTN DNA长1128 bp,编码375个氨基酸.藏鸡与原鸡氨基酸序列一致率为99.7％,有6个同义突变和1个非同义突变的氨基酸差异.MSTN mRNA在腿肌、胸肌、心脏、肾脏、睾丸、卵巢、胃中均检测到表达,脂肪、肝脏、肺中未检测到MSTN mRNA表达.MSTN mRNA表达水平由高到低的顺序为:腿肌、胸肌、心脏、肾脏、睾丸、卵巢和胃.     

羊口疮病毒B2L基因的原核表达、纯化及鉴定

[目的]获取羊口疮病毒B2L基因编码蛋白。[方法]根据GenBank上羊口疮病毒ORFV/ShanXi/2011/China株B2L基因序列,设计并合成1对特异性引物,利用PCR方法扩增B2L全基因序列,然后将扩增的B2L基因克隆到PMD18-T载体上;对构建的重组克隆质粒(PMD18-T-B2L)经过测序鉴定后,将目的基因亚克隆到PET-32a(+)原核表达载体上,获得重组表达质粒PET-32a-B2L,然后通过双酶切和测序进行鉴定;将重组菌于37℃、终浓度含1 mM IPTG的LB培养基中,诱导表达3h后进行SDS-PAGE分析;表达的目的蛋白经过层析纯化后,进行Western Blot鉴定。[结果]原核表达重组质粒构建成功;SDS-PAGE鉴定发现目的条带的分子量与预期大小相符;纯化的目的蛋白经Western Blot鉴定正确,表明蛋白表达成功。[结论]本研究成功构建了羊口疮病毒B2L基因原核表达重组质粒,并成功表达和纯化了B2L蛋白,为后续羊口疮病毒检测方法的建立打下了基础。     

Pharmacokinetic/pharmacodynamic relationship of marbofloxacin against Pasteurella multocida in a tissue‐cage model in yellow cattle

The fluoroquinolone antimicrobial drug marbofloxacin was administered to yellow cattle intravenously and intramuscularly at a dose of 2 mg/kg of body weight in a two‐period crossover study. The pharmacokinetic properties of marbofloxacin in serum, inflamed tissue‐cage fluid (exudate), and noninflamed tissue‐cage fluid (transudate) were studied by using a tissue‐cage model. The in vitro and ex vivo activities of marbofloxacin in serum, exudate, and transudate against a pathogenic strain of Pasteurella multocida (P. multocida) were determined. Integration of in vivo pharmacokinetic data with the in vitro MIC provided mean values for the area under the curve (AUC)/MIC for serum, exudate, and transudate of 155.75, 153.00, and 138.88, respectively, after intravenous dosing and 160.50, 151.00, and 137.63, respectively, after intramuscular dosing. After intramuscular dosing, the maximum concentration/MIC ratios for serum, exudate, and transudate were 21.13, 9.13, and 8.38, respectively. The ex vivo growth inhibition data after intramuscular dosing were fitted to the inhibitory sigmoid E_max equation to provide the values of AUC/MIC required to produce bacteriostasis, bactericidal activity, and elimination of bacteria. The respective values for serum were 17.25, 31.29, and 109.62, and slightly lower values were obtained for transudate and exudate. It is proposed that these findings might be used with MIC₅₀ or MIC₉₀ data to provide a rational approach to the design of dosage schedules which optimize efficacy in respect of bacteriological as well as clinical cures.     

日粮添加LA和DHA对乳脂脂肪酸含量及比值的影响

本试验选用带有永久性瘤胃、十二指肠和回肠瘘管的泌乳荷斯坦奶牛4头,采用4×4拉丁方试验设计,研究日粮添加亚油酸(LA)和二十二碳六烯酸(DHA)对乳常规组成、消化道各段食糜pH以及乳脂脂肪酸构成的影响.试验结果表明:添加LA和DHA不影响乳蛋白和乳糖含量(P>0.05),而添加DHA有显著降低乳脂含量的趋势(P>0.05);日粮共同添加LA与DHA能提高十二指肠前消化道的pH,但差异不显著(P>0.05),而单独添加DHA显著降低了回肠的pH(P<0.05);日粮单独添加DHA增加乳脂中C23:0脂肪酸的含量,但并不降低乳脂中总饱和脂肪酸量.与对照组相比,LA与DHA共同添加使乳脂中总多不饱和脂肪酸增加了100%(P<0.05).LA与DHA共同添加使乳脂中饱和脂肪酸/不饱和脂肪酸由3.18降低至1.24(P<0.05).添加DFIA使乳脂中总单不饱和脂肪酸/多不饱和脂肪酸由5.94降低至3.00(P<0.05).上述研究结果表明,日粮添加LA和DHA可改变乳脂中脂肪酸的组成和比例,有利于人体健康,但DHA使产奶量有一定程度的降低.