饲料中呕吐毒素对不同阶段商品猪及种猪的影响

我国不仅是畜牧业生产和消费大国,同时饲料产量也居世界首位,作为饲料中最常添加的谷物原料,其质量安全对饲料生产和养殖业有着重要影响。小麦、玉米等谷物在其生长、收获及加工等阶段未及时按规定处理会产生大量的霉菌毒素,其中呕吐毒素最为常见。呕吐毒素(DON)主要由镰刀菌属(如禾谷镰刀菌、尖孢镰刀菌等)产生,会造成不同阶段商品猪及种猪呕吐、肌肉出血、生长性能和繁殖力的下降等。本文综述了饲料中DON的污染现状及其对养猪生产的危害,进而提出了综合防治措施,为畜牧业生产者更好地防治DON污染、提高养殖收益提供系统科学参考。     

政策认知、执行力度与资源化利用满意度——基于河北省380家生猪养殖主体调研数据(上)

参与主体对于政策的评价是衡量政策实施效果的重要指标，探明政策参与主体满意度影响因素有助于了解主体自身需求，从而提高政策实施水平。文章基于对河北省380家生猪养殖主体调研数据，运用多元有序Logistic回归方法，分析生猪养殖主体自身政策认知以及相关政策执行力度对畜禽养殖主体废弃物资源化利用满意度的影响。结果表明：养殖主体资源化利用政策了解程度能够显著提升其资源化利用政策满意度；仅考虑养殖主体政策参与力度，随着参与力度增加，满意度亦会显著提升。但综合考虑其他因素，参与力度对于满意度提升效果则不再显著；养殖主体感知政策执行力度增加不利于政策满意度提升。此外，生猪养殖主体废弃物资源化利用政策了解程度增加，可以显著提升其报告资源化利用政策“满意”可能性。而单纯提高资源化利用政策执行力度并不能显著提高养殖主体资源化利用政策满意度。因此，要提高养殖主体政策满意度，应多渠道提升宣传力度，鼓励养殖主体积极参与，提高其参与意识，不断改善现有政策执行方式。     

猪RUVBL2真核表达载体的构建及其在CHO细胞中的表达

RUVBL2(RuvB-like 2)蛋白是进化上高度保守AAA+(ATPases Associated With Diverse Cellular Activities,AAA)家族成员之一,CHO(Chinese Hamster Ovary)细胞被广泛地用于表达重组DNA蛋白。为探究猪睾丸组织的RUVBL2基因是否能够在CHO细胞中表达,本实验以猪睾丸组织的cDNA为模板,PCR扩增RUVBL2目的基因,并将其克隆至pIRES2-EGFP(Mammalian Expression Vectors pIRES2-EGFP)载体上,进一步转化到DH5α中,再进行PCR、酶切及测序鉴定;将重组质粒转染到CHO细胞中,再进行荧光、RT-PCR、Western blot检测。结果显示:PCR、酶切及测序都证实了RUVBL2基因正确地插入到了载体质粒pIRES2-EGFP的多克隆位点;荧光、RT-PCR、Western blot也证实了RUVBL2基因在CHO细胞中的成功表达。本实验成功构建了猪的pIRES2-EGFP-RUVBL2真核表达载体,并证实了猪睾丸组织中的RUVBL2基因能够在CHO细胞中表达。     

Transmission of methicillin-resistant Staphylococcus aureus strains between different kinds of pig farms

The main objective of the present study was to investigate if different kinds of pig farms, like farrowing farms and rearing farms, play a role in the transmission of methicillin-resistant Staphylococcus aureus (MRSA) to Dutch finishing farms. Twelve farrowing farms, 11 finishing farms, 6 farrow-to finish farms, 1 rearing farm and 1 centre for artificial insemination were included. Screening of 310 pigs from these 31 farms showed 35 pigs (11%) to carry MRSA in their nares. On 7 of the 31 (23%) investigated farms colonized pigs were found, including 3 finishing farms, 3 farrowing farms and 1 farrow-to-finish farm. The use of standard antimicrobial medication of the pigs seemed to be a risk factor for MRSA carriage. Screening of the pigs on six farms supplying pigs for the MRSA positive farms revealed that the pigs on all but one farm were MRSA positive. Genotyping revealed that all MRSA strains were non-typeable by PFGE using the SmaI restriction enzyme and had multilocus sequence type (MLST) ST398. Different spa-types were found including t011, t108, t567, t899 and t1939, but the spa-types on epidemiologically related farms were identical indicating that MRSA are transmitted between farms through the purchase of colonized pigs. Two SCCmec types were found among the MRSA: type IV and type V. SCCmec type V was predominant. On two farms MRSA isolates with ST398, the same spa-type but with different SCCmec types (IV and V) were found, suggesting that different SCCmec elements have been inserted into MSSA with the same genotype. All MRSA strains were resistant to tetracycline, but additional resistances to erythromycin, lincomycin, kanamycin and gentamicin were also found. All MRSA isolates were negative for the exfoliative toxin genes (eta and etb), PVL toxin genes (lukF and lukS), toxic shock syndrome gene (tst-1), and the leukotoxin genes (lukE, lukD, lukM, lukF').     

IGF-I- and EGF-dependent DNA synthesis of porcine myoblasts is influenced by the dietary isoflavones genistein and daidzein

Soy-derived isoflavones have been reported to be specific inhibitors of protein tyrosine kinases like the type 1 insulin-like growth factor receptor (IGF-1R) and the epidermal growth factor receptor (EGFR). This study was conducted to investigate, whether IGF-I and EGF stimulate porcine myoblast growth and whether the responses are influenced by isoflavones. Satellite cell-born myoblasts derived from the semimembranosus muscle of newborn piglets were treated for 26h with IGF-I or EGF alone and in combination with genistein or daidzein. The DNA amount was measured and DNA synthesis was recorded as 6 h-[(3)H]thymidine incorporation during exponential growth in serum-free basal medium. IGF-I and EGF synergistically stimulated DNA synthesis of porcine myoblast with EGF causing a greater response. Genistein (100mumol/l) effectively reduced the growth factor-mediated DNA synthesis, which was associated with an inhibition of growth factor receptor protein expression. In response to daidzein no reduction in growth factor-mediated DNA synthesis was found. Daidzein (1; 10mumol/l) combined with IGF-I caused even a slight increase in DNA amount compared with the untreated control. The expression of the IGF-1R precursor protein was reduced with 10 and 100mumol/l daidzein, whereas the EGFR expression remained unchanged with daidzein. The results suggest that dietary isoflavones may interact with growth factor-induced stimulation of pig skeletal muscle growth.     

新生猪肌组织成纤维细胞的分离培养和鉴定

研究建立了猪肌组织成纤维细胞体外培养的模型,采用组织块培养方法获得了新生猪肌组织成纤维细胞并进行体外培养.观察细胞形态,通过绘制细胞的生长曲线来研究肌组织成纤维细胞的生长规律,利用RT-PCR和免疫细胞化学染色对所获得的细胞进行鉴定,再用双荧光素酶检测系统来检测细胞的转染效率.通过形态学观察、RT-PCR和免疫细胞化学染色结果表明,已成功培养了猪肌组织成纤维细胞,纯度达90%以上.     

BPI基因在梅山猪初生断奶以及成年阶段的组织表达谱分析

为探讨杀菌/通透性增强蛋白(BPI)基因在梅山猪从初生到成年各个时期不同组织中的表达规律,利用qPCR检测初生、断奶、性成熟、体成熟4个重要发育时期(即1、35、134、158日龄)梅山猪的心脏、肝脏、脾脏、肺脏、肾脏、胃、肌肉、胸腺、淋巴结、十二指肠、空肠和回肠12个组织中BPI基因的表达水平。结果表明:4个不同发育阶段BPI基因的组织表达谱在心脏、肝脏、脾脏、肌肉和胸腺中均表现出相对一致的规律,即BPI基因的表达量一直处于极低水平,而在肠道组织中从初生到成年各时期均高度表达;BPI基因在胃中的表达程度随着日龄增长而显著提高;在小肠组织中,35日龄断奶仔猪BPI基因的表达水平极显著高于其他3个日龄。综上,推断肠道中BPI基因的高度表达是仔猪从初生就具有的抵抗大肠杆菌等病原感染属固有免疫的一部分,而在胃中的表达很可能是其后天为了抵御不断侵染的大肠杆菌等病原的结果。     

A comparably high virulence strain of porcine reproductive and respiratory syndrome virus isolated in Taiwan

Porcine reproductive and respiratory syndrome virus (PRRSV) has been endemic in Taiwan since 1991. This study aimed to present a highly virulent PRRSV in Taiwan based on farm data collection and both in vitro and in vivo evaluations in virus challenge studies. This virulent PRRSV strain was first noticed on Farm TSYM due to continuously high nursery mortality rate and severe PRRSV-associated pneumonia. In phylogenetic surveillance, the PRRSV TSYM-strain remained in the predominant position for years, even with several other PRRSV strain invasions. In laboratory challenge trials, the TSYM-strain led to prolonged pyrexia, growth retardation, high mortality rates and high viremia titer that similar to the highly pathogenic PRRSV. The TSYM-strain isolate also triggered early interleukin-10 up-regulation and significantly higher infection rates under in vitro experiments. This study provides information of a comparably virulent strain in Taiwan and its appearance in both farm and laboratory levels.     

Effect of controlled alterations in maternal dietary retinol on foetal and neonatal retinol status and pregnancy outcome in pigs

The objective of this experiment was to examine the effects of feeding a vitamin A deficient diet (VAF) to pigs at different times on day 100 of foetal and days 0, 1 and 2 of neonatal development. Three treatments included a control (n = 12), VAF for 100 days before mating and during the first month of pregnancy (n = 13; VAF–control), and VAF during the oestrous cycle before mating and throughout pregnancy (n = 13; control–VAF). On day 100 of pregnancy, maternal liver and plasma retinol concentrations were reduced in both groups of gilts fed a vitamin A free diet compared to controls (P < 0.001 and P < 0.01, respectively). Day 100 foetal liver retinol concentrations were not affected by dietary treatment, whereas foetal plasma concentrations were higher in foetuses carried by gilts fed the VAF–control diet (P < 0.05). Piglets born to mothers fed the control–VAF, but not the VAF–control diet had consistently lower hepatic and plasma liver retinol concentrations (P < 0.05). Moderate reductions in maternal vitamin A at either stage of pregnancy did not affect pregnancy rate, litter size, progesterone secretion or the allometric relationships between foetal or neonatal organ and total body size. Reduced vitamin A during conception and early pregnancy, but not during later pregnancy, was associated with increased within-litter uniformity in birth weight (P < 0.05) and a tendency for fewer low birth weight piglets, but this needs to be confirmed in a greater number of sows. The mechanism underlying this effect is not known, but appears to not involve an alteration in progesterone production.     

Risk factors associated with porcine cysticercosis in selected districts of Eastern and Southern provinces of Zambia

To determine the risk factors associated with Taenia solium transmission in humans and pigs in the rural areas of Eastern and Southern provinces of Zambia, a questionnaire was administered in 788 households from 155 villages. Pigs were examined from 800 households. Tongue examination and enzyme-linked immunosorbent assay (Ag-ELISA) for the detection of circulating antigens of T. solium cysticerci were used to measure infection in pigs. A snowballing technique was utilised to select households with pigs. Prevalence of households with pigs infected with T. solium on tongue examination by district ranged from 12.7% to 32.1% with Ag-ELISA having a range of 30.0-51.7%. Of the total number of households visited, 18.8% and 37.6% had at least one pig positive for porcine cysticercosis on tongue examination and Ag-ELISA, respectively. Risk factors associated with T. solium infection were lack of pork inspection at slaughter (96.7%), consumption of pork with cysts (20.1%), selling of pork infected with T. solium cysticerci (18.3%), free-range husbandry system (83.2%) and absence of latrines (58.0). Free-range husbandry system (OR=1.68; 95% CI=1.36-2.07) was a significant risk factor for porcine cysticercosis in the surveyed areas. The result that pigs were mostly kept on free-range and semi-intensive husbandry systems may have permitted them to have access to eating human faeces that could be contaminated with tapeworm eggs. This study has shown that T. solium infection poses a high public health risk in the study areas and urban areas as well. We recommend that a human survey be conducted to verify the human exposure to taeniasis and/or cysticercosis in Zambia.