云南省昆明市动物园大肠杆菌分离株毒力基因分布特征

为研究云南省昆明市动物园动物体内大肠杆菌(E.coli)分离株毒力基因的分布特征,从圆通山动物园37个动物种群粪便中分离出37株E.coli,采用生化鉴定方法鉴定大肠杆菌,PCR方法检测19种毒力基因。鉴定结果表明:37株E.coli中,ompA、iroN、fimC、aatA、vat 5种毒力基因携带率分别为100%、95.49%、83.78%、70.27%、51.35%,ibeA、neuC、iutA、traT、stx 5种毒力基因携带率为0,其他9种毒力基因携带率均低于40.00%;分离菌株普遍携带8种以下毒力基因,同时携带10种以上毒力基因的概率为8.10%;分离株强毒力岛基因携带率较高,分布较为普遍。结果表明,昆明市圆通山动物园内流行的大肠杆菌以致病性大肠杆菌为主,不同种类动物体内大肠杆菌的毒力基因携带率存在较大差异,其原因可能与动物的饲养环境以及动物自身的适应能力和抵抗力有关。因此,对于动物园内具有较高大肠杆菌致病风险的动物,要采取相应防治措施,防止大肠杆菌病发生与流行。     

某规模场仔猪伪狂犬病免疫抗体消长规律初探

为给规模猪场猪伪狂犬病(PR)免疫程序制定提供参考,在贵州省某规模猪场选取3组不同母源抗体背景仔猪群,按照不同的免疫程序进行PR疫苗免疫,然后设置不同的检测时间点,采集猪血清采用ELISA方法进行gE和gB抗体跟踪检测,初步探索仔猪群免疫抗体消长规律。结果显示:在母源gE和gB抗体均为阴性背景下,1日龄初生仔猪活疫苗滴鼻免疫对免疫抗体水平没有影响,15日龄基因缺失疫苗注射免疫后,免疫抗体水平逐渐升高,45日龄基因缺失疫苗加强免疫1个月后,免疫抗体水平达到顶峰,此后逐渐下降,到120日龄时,仍有50%的有效保护率;在gE母源抗体阴性背景下,产前40 d免疫母猪,55日龄进行基因缺失疫苗注射免疫后,仔猪免疫抗体水平持续升高,90日龄时再用基因缺失疫苗加强注射免疫1次,至120日龄免疫抗体水平达到顶峰,150日龄后开始下降,到185日龄时,仍有50%的有效保护率;在母源gE抗体阳性背景下,疫苗免疫不能使仔猪产生有效的免疫保护抗体。结果表明,仔猪母源抗体背景对于仔猪免疫程序的制定具有较大影响,合理的免疫程序要结合母源抗体和免疫抗体检测结果合理制定,并要及时淘汰gE阳性种猪。     

畜禽产品兽药残留超标案件的法律适用

畜禽产品兽药残留是政府关注、社会关切和消费者关心的食品安全问题。执法实践中,执法人员对畜禽养殖、畜禽收购与屠宰、畜禽产品市场销售等环节如何适用法律存在执法困惑。本文结合有关法理分析认为:一是养殖环节销售兽药残留超标的动物或动物产品的,应根据《兽药管理条例》对养殖者进行处罚。二是屠宰环节畜禽产品兽药残留超标的,要以违法行为是否构成为判定要素。对于畜禽产品尚未销售的,相关主体没有法律责任,但应对问题畜禽产品进行无害化处理,防止用于食品消费。对于畜禽产品已销售的,应根据《农产品质量安全法》对相关违法行为人进行处罚。在自营模式和代宰模式中,违法行为人认定和法律责任归属有所不同。三是市场销售环节发现畜禽产品兽药残留超标,应由食品药品监管部门按照《食品安全法》处罚,农业执法部门应防止越权执法。     

新疆某猪场母猪繁殖障碍病病原学检测和毒株鉴定

2018年4月,新疆某规模化繁育猪场出现大量母猪流产,产死胎、木乃伊胎等繁育障碍症状。为确诊病因,采集胎儿组织和母猪流产分泌物,通过普通PCR、RT-PCR、real-timePCR技术,对猪繁殖与呼吸综合征病毒(PRRSV)、伪狂犬病病毒(PRV)、猪细小病毒(PPV)、弓形虫4种病原进行检测。结果显示,PRRSV检测呈阳性,PRV、PPV和弓形虫检测呈阴性。通过PRRSV特异性引物NSP2进行PRRSV毒株鉴定,确定该猪场存在PRRSV类NADC30毒株。结果表明,类NADC30毒株是导致该猪场出现母猪繁殖障碍的重要病原,说明该新型毒株已经蔓延到新疆地区,并开始对该地生猪养殖业造成危害。本试验为新疆地区猪场母猪繁殖障碍的病因调查提供了依据。     

Immunomodulatory effect of γ‐irradiated Astragalus polysaccharides on immunosuppressed broilers

In this study, we irradiated Astragalus polysaccharides (APS) using 25 kGy ⁶⁰Co γ ray to obtain γ‐irradiated Astragalus polysaccharides (IAPS) and then investigated the effects of IAPS on growth performance and immune function of cyclophosphamide (CPM)‐treated broilers. The physicochemical properties of APS and IAPS (molecular weight, water solubility, viscosity, morphological and structural properties) were evaluated. Then, 384 one‐day‐old Arbor Acres broiler chicks with similar initial weight were randomly assigned into 6 groups: the non‐treated group (control), and CPM‐treated groups were fed either a basal diet or the diets containing 900 mg/kg APS, or 900, 600, 300 mg/kg IAPS, respectively. On days 16, 18, and 20, all broilers except for the control group were intramuscularly injected with 0.5 ml CPM (40 mg/kg·BW). Broilers in the control group were intramuscularly injected with 0.5 ml sterilized saline (0.75%, wt/vol). This trial lasted for 21 days. The physicochemical treatment showed that γ irradiation could decrease the molecular weight and viscosity, and increase the water solubility of APS (p < 0.05), whereas the structural properties of APS was not affected. In the animal trial, 900 mg/kg APS or 900, 600 mg/kg IAPS relieved the decreased growth performance, thymus index, T lymphocytes proliferation, serum IgG concentration, NOS activity and the increased blood heterophil:lymphocyte ratio in CPM‐treated broilers (p < 0.05). CPM‐induced decreases in B lymphocytes proliferation and serum IgM concentration were only increased by IAPS at 900 mg/kg (p < 0.05). Overall, both APS and IAPS alleviated CPM‐induced immunosuppression. Especially, IAPS possessed better immunomodulatory effect than APS, indicating that γ irradiation could be used as an effective method to enhance the immunomodulatory activity of APS.     

Effect of genistein on IGF‐1 and IGFBP‐1 in young and aged female rat ovary

The objective of this study was to assess the effects of genistein (GEN) on expression of insulin‐like growth factor 1 (IGF‐1) and insulin‐like growth factor binding protein 1 (IGFBP‐1) in young and aged rat ovary. Forty young female Sprague Dawley (SD) rats (200 ± 20 g) and forty aged female SD rats (490 ± 20 g) were selected and according to weight, they were divided into the following five groups with eight animals in each: negative control group (NC), low‐dose group (L), middle‐dose group (M), high‐dose group (H) and positive control group (PC). GEN group received GEN of 15, 30, 60 mg/kg respectively. It lasted 30 days. Concentrations of serum hormones, IGF‐1 and IGFBP‐1 were determined by enzyme‐linked immunosorbent assay (ELISA). Gene and protein expressions of IGF‐1 and IGFBP‐1 were determined by real‐time PCR and Western blot respectively. Compared with NC, GEN significantly increased oestradiol‐17β(E₂) level in aged rat, reduced luteinizing hormone (LH) level in young and aged rat. Serum levels of IGFBP‐1 in young rats were significantly higher in GEN groups (p < 0.05). mRNA and protein expression levels of IGF‐1 and IGFBP‐1 were positively correlated with GEN dose. GEN could significantly reduce the ratio of IGF‐1/IGFBP‐1 of aged rats. Multivariate Cox regression analysis result showed IGF‐1 and IGFBP‐1 levels significantly correlated with GEN dose. We speculate that there is an association between the addition of GEN and expression of IGF‐1 and IGFBP‐1, and the relationship between them is different in young and aged rat.     

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.     

Combined microRNAome and transcriptome analysis of follicular phase and luteal phase in porcine ovaries

The aim of this study was to explore the expression difference of miRNAs and mRNAs between the follicular phase (FP) and luteal phase (LP) in porcine ovaries and provide a theoretical basis for the research on mammalian reproductive regulation. RNA‐Seq and miRNA‐Seq were used to identify differentially expressed genes (DEGs) and miRNAs (DEMs) between the FP and LP in ovaries of six sows (3‐year‐old Yorkshire pigs with similar weights and same parities). Bioinformatic analysis was used to screen potential genes and miRNAs related to porcine ovarian function. Real‐time qualitative PCR was used to validate the sequencing results. RNA‐Seq results showed that 3,078 genes were up‐regulated, and 1,444 genes were down‐regulated in the LP compared with the FP, and DEGs were significantly enriched in 242 Gene Ontology (GO) terms and 33 Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways. miRNA‐Seq identified 112 DEMs, of which 25 were up‐regulated and 87 were down‐regulated in the LP compared with the FP. We obtained 186 intersection genes (IGs) between the 4,522 DEGs and 2,444 target genes predicted from the 112 DEMs. After constructing a miRNA‐gene‐pathway network, we identified key miRNAs and genes including miR‐17‐3p, miR‐214, miR‐221‐5p, miR‐125b, FGF1, YWHAG, YWHAZ, FDFT1 and DHCR24, which are enriched in Hippo and PI3K‐Akt signalling pathways, and various metabolic pathways. These results indicate that these key genes and miRNAs may play important roles in the developmental transition from FP to LP in porcine ovaries and represent candidate targets for further study.     

应用荧光定量RT-PCR检测J亚群禽白血病病毒

针对J亚群禽白血病病毒（ALV-J）基因序列保守区域设计一对特异性引物和一条特异性探针,通过构建重组阳性标准质粒作为阳性标准品,建立了检测ALV-J核酸的荧光定量PCR方法。优化反应体系和条件后进行特异性、敏感性、重复性试验。结果显示,该检测方法特异性强,与其它禽源病毒如A亚群禽白血病病毒（ALV-A）、B亚群禽白血病病毒（ALV-B）、新城疫病毒（ NDV）、禽流感病毒（AIV）、鸡传染性贫血病毒（CIAV）和马立克病病毒（MDV）均不发生交叉反应;该方法可检测到3.2×102拷贝/μL的病毒核酸,与常规RT-PCR相比,敏感性高100倍;重复性试验的变异系数小于2%。研究结果表明,建立的Real-time RT-PCR 检测方法特异性强、灵敏度高、可重复性好,可用于ALV-J的定量检测。