药物饲料添加剂吉他霉素耐药性风险评估

目的 为给兽药减量政策的制定、动物源性食品安全的维护提供理论依据。方法 利用每日允许摄入量（ADI）、估算每日摄入量（EDI）及慢性风险熵（CRQ），对中国居民通过摄入肉蛋乳等动物性食品暴露于吉他霉素的耐药性风险进行点评估。结果 随着年龄增长，中国居民的吉他霉素膳食暴露量逐渐降低。2～7岁人群吉他霉素的膳食暴露量最高，男女分别为2.17和2.29 μg/ ( kg·bw·d)；＞65岁人群膳食暴露量最低，男女分别为0.45和0.46 μg/ ( kg·bw·d)。2～7岁人群通过摄入乳制品的吉他霉素的膳食暴露量最大，男女分别为1.15和1.22 μg/ ( kg·bw·d)，8岁以上人群通过摄入肉类食品的吉他霉素的膳食暴露量最大。中国居民通过摄入肉蛋乳等动物性食品暴露于吉他霉素，各年龄段CRQ均小于1。其中2～7岁人群CRQ值最高，风险最大；65岁以上人群CRQ值最低，风险最小。结论 中国居民通过摄入动物性食品的吉他霉素耐药性风险较低，危害程度较小，但儿童通过摄入乳制品的吉他霉素耐药性风险较高，有必要制定乳制品中吉他霉素残留的限量标准。     

Seneca Valley virus RNA detection in pig feed and feed ingredients in Brazil

We investigated Seneca Valley virus (SVV) contamination in pig feed and feed ingredients. Twenty‐seven samples were collected from two Brazilian feed mills and subjected to conventional RT‐nested‐PCR and qRT‐PCR assays. Seven samples were SVV‐positive with viral loads of 3.94–4.33 log₁₀ genomic copies/g of feed. The study reveals SVV feed and feed ingredient contamination under natural conditions in Brazil.     

单纯胸外按压课程在高校人群心肺复苏培训中的应用

目的分析单纯胸外按压(chest compression cardiopulmonary resuscitation,CC-CPR)课程对高校人群胸外按压培训效果,探索心肺复苏公众培训新形式。方法招募120名高校人群随机分为CC-CPR课程组、Heart-saver CPR&AED First Aid(HS)课程组。两组分别进行不同课程培训,通过SUNLIFE Palm CPR胸腔按压反馈仪收集培训后按压数据,比较两组平均按压深度、平均按压频率、正确按压率、按压深度达标率、按压频率达标率、不良按压率。结果CC-CPR课程组在按压平均深度、频率上达到与HS课程组相同的培训效果,但在胸外按压达标率上比较,CC-CPR课程组比HS课程组在按压正确率、按压深度达标率、按压频率达标率上都有显著提升(P<0.05)。从不良胸外按压上比较,两组在滞留按压率、过深按压率、过慢按压率上都控制良好;但在过浅按压和过快按压发生率比较,CC-CPR课程组明显少于HS课程组,差异有统计学意义(P<0.05)。结论CC-CPR课程可使高校人群获得较HS课程更优的按压质量,且效率更高,是普及高校人群CPR培训方式的一种尝试与创新。     

African swine fever risk and plant-based feed ingredients: Canada's approach to risk management of imported feed products

As a result of unprecedented spread of African swine fever (ASF) since 2018, Canada has taken additional steps to prevent introduction of the virus. While the role of plant-based feed in the transmission of ASF is not completely understood, it was identified that no mitigation measures were in place to address this uncertain risk. A risk analysis process was conducted with collaboration between government and industry, including an assessment of the costs and benefits of various risk mitigation options. Using existing legislative tools, requirements must now be met before the importation of plant-based feed ingredients of concern is permitted. Even with an uncertain risk, countries such as Canada that would suffer severe consequences should ASF be introduced, need to consider appropriate, risk-based mitigation measures.     

Feed or feed transport as a potential route for a porcine epidemic diarrhoea outbreak in a 10,000-sow breeding herd in Mexico

Porcine epidemic diarrhoea virus (PEDV) infects pigs of all ages causing vomiting and diarrhoea. PEDV is transmitted via the oral–faecal route, and a very low dose is enough to infect susceptible pigs, resulting in significant production losses. This short communication aims to describe the introduction of PEDV into a 10,000-sow farrow-to-wean farm located in northwest Mexico. Following the onset of clinical signs, an outbreak investigation was conducted to determine the most probable route of introduction. Based on data collected from interviews, construction of a timeline of events, and the detection of PEDV RNA in feed samples and samples collected from various surfaces of feed transport vehicles, it was concluded that the most probable route for PEDV incursion into this breeding herd was contaminated feed or a contaminated feed transport vehicle. This paper describes how feed or feed transport could serve as potential routes of PEDV infection to a farm and highlights the importance of establishing biosecurity programs to mitigate these risks.     

Rethinking the uncertainty of African swine fever virus contamination in feed ingredients and risk of introduction into the United States

Economically relevant pathogens, such as African swine fever virus (ASFV), have been shown to survive when experimentally inoculated in some feed ingredients under the environmental conditions in transoceanic transport models. However, these models did not characterize the likelihood of virus survival under various time and temperature processes that feed ingredients undergo before they are added to swine diets. Here, we developed a quantitative risk assessment model to estimate the probability that one or more corn or soybean meal ocean vessels (25,000 tonnes) contaminated with ASFV would be imported into the United States annually. This final probability estimate was conditionally based on five likelihoods: the probability of initial ASFV contamination (p0), ASFV inactivation during processing (p1) and transport (p2), recontamination (pR), and ASFV inactivation while awaiting customs clearance at United States entry (p3). The probability of ASFV inactivation was modelled using corn and soybean (extruded or solvent extracted) processing conditions (times and temperatures), D-values (time to reduce 90% or 1-log) estimated from studies of ASFV thermal inactivation in pork serum (p1), and survival in feed ingredients during transoceanic transport (p2 and p3). ‘What-if’ scenarios using deterministic values for p0 and pR (1%, 10%, 25%, 50%, 75%, and 100%) were used to explore their impact on risk. The model estimated complete inactivation of ASFV after extrusion or solvent extraction processes regardless of the initial ASFV contamination probability assumed. The value of recontamination (ranging from 1% to 75%) was highly influential on the risk of one ASFV-contaminated soybean meal vessel entering the United States. Median risk estimates ranged from 0.064% [0.006%–0.60%; 95% probability interval (PI)], assuming a pR of 1.0%, up to 4.67% (0.45%–36.50% 95% PI) assuming a pR of 75.0%. This means that at least one vessel with ASFV-contaminated soybean meal would be imported once every 1563–21 years, respectively. When all raw corn was assumed to be contaminated (p0 = 100%), and no recontamination was assumed to occur (pR = 0%), the median probability of one vessel with ASFV-contaminated corn entering the United States was 2.02% (0.28%–9.43% 95% PI) or once every 50 years. Values of recontamination between 1% and 75% did not substantially change the risk of corn. Days of transport, virus survival during transport (D-value), and number of vessels shipped were the parameters most influential for increased likelihood of a vessel with ASFV-contaminated soybean meal or corn entering the United States. The model helped to identify knowledge gaps that are most influential on output values and serves as a framework that could be updated and parameterized as new scientific information becomes available. We propose that the quantitative risk assessment model developed in this study can be used as a framework for estimating the risk of ASFV entry into the United States and other ASFV-free countries through other types of imported feed ingredients that may potentially become contaminated. Ultimately, this model can be used to develop risk mitigation strategies and critical control points for inactivating ASFV during feed ingredient processing, storage, and transport, and contribute to the design and implementation of biosecurity measures to prevent the introduction of ASFV into the United States and other ASFV-free countries.     

Effects of Dietary Exposure to Zearalenone (ZEN) on Carp (Cyprinus carpio L.)

The mycotoxin zearalenone (ZEN) is frequently contaminating animal feeds including feed used in aquaculture. In the present study, the effects of dietary exposure to ZEN on carp (Cyprinus carpio L.) were investigated. ZEN at three different concentrations (low dose: 332 µg kg⁻¹, medium dose: 621 µg kg⁻¹ and high dose: 797 µg kg⁻¹ final feed, respectively) was administered to juvenile carp for four weeks. Additional groups received the mycotoxin for the same time period but were fed with the uncontaminated diet for two more weeks to examine the reversibility of the ZEN effects. No effects on growth were observed during the feeding trial, but effects on haematological parameters occurred. In addition, an influence on white blood cell counts was noted whereby granulocytes and monocytes were affected in fish treated with the medium and high dose ZEN diet. In muscle samples, marginal ZEN and α-zearalenol (α-ZEL) concentrations were detected. Furthermore, the genotoxic potential of ZEN was confirmed by analysing formation of micronuclei in erythrocytes. In contrast to previous reports on other fish species, estrogenic effects measured as vitellogenin concentrations in serum samples were not increased by dietary exposure to ZEN. This is probably due to the fact that ZEN is rapidly metabolized in carp.     

补饲高蛋白饲料对西门塔尔产后母牛繁殖性能的影响

为了确定补饲高蛋白饲料对产后母牛繁殖性能的效果,选择30头西门塔尔产后母牛在产后90 d内持续补饲高蛋白饲料。利用直肠检查及B超监测技术在母牛产后15 d、30 d、45 d、60 d、90 d时对子宫恢复情况及卵巢状态变化进行检查,并及时记录胎衣、恶露以及发情配种情况。结果表明,产后母牛补饲高蛋白饲料300 g/d,繁殖性能发生了明显的改善。     

Bacillus spp. as direct-fed microbial antibiotic alternatives to enhance growth,immunity, and gut health in poultry

The increasing occurrence of antibiotic-resistant bacteria combined with regulatory pressure and consumer demands for foods produced without antibiotics has caused the agricultural industry to restrict its practice of using antibiotic growth promoters (AGP) in food animals. The poultry industry is not immune to this trend, and has been actively seeking natural alternatives to AGP that will improve the health and growth performance of commercial poultry flocks. Bacillus probiotics have been gaining in popularity in recent years as an AGP alternative because of their health-promoting benefits and ability to survive the harsh manufacturing conditions of chicken feed production. This review provides an overview of several modes of action of some Bacillus direct-fed microbials as probiotics. Among the benefits of these direct-fed microbials are their production of naturally synthesized antimicrobial peptides, gut flora modulation to promote beneficial microbiota along the gastrointestinal tract, and various immunological and gut morphological alterations. The modes of action for increased performance are not well defined, and growth promotion is not equal across all Bacillus species or within strains. Appropriate screening and characterization of Bacillus isolates prior to commercialization are necessary to maximize poultry growth to meet the ultimate goal of eliminating AGP usage in animal husbandry.