四川地区藏猪戊型肝炎病毒的检测和遗传演化分析

旨在调查四川地区藏猪戊型肝炎病毒（hepatitis E virus，HEV）的流行情况和遗传演化，作者用RT-PCR法对2018—2020年采集自四川省甘孜藏族自治州和阿坝藏族自治州的22个藏猪场332份藏猪粪便样本进行HEV检测，并对阳性样本进行基因分型。RT-PCR检测结果表明HEV核酸阳性率为20.48%（68/332，95% CI=16.3%~25.2%），22个规模藏猪场中HEV猪场阳性率为77.27%（17/22，95% CI=54.6%~92.2%），健康样本阳性率为2.86%（3/105，95% CI=0.6%~8.1%），腹泻样本阳性率为28.63%（65/227，95% CI=22.8%~35.0%），系统进化分析显示所有阳性株均为G4型。为了进一步研究该地区流行毒株的演化过程，以贝叶斯进化分析软件进行分歧时间估算，结果表明，藏猪流行毒株的分歧时间最早为1999年，最晚为2016年。并分别从每年的样本中挑选1份阳性样本得到全基因组序列，核酸序列相似性为89.5%~93.1%。通过对3条全基因组重组分析发现SWU/301/2019存在重组现象，SWU/301/2019重组区域位于ORF1的3 746—4 655 bp。本研究首次对四川地区藏猪源HEV进行调查，结果表明四川藏猪中存在一定程度的HEV感染，为四川地区对藏猪感染HEV的防治以及深入研究四川藏猪源HEV遗传变异及生物学特性提供了参考依据。     

以“猪疫情”与“猪周期”叠加致肉价波动为契机建立新时代立体生态养殖产业链

该文从2019年中国生猪和猪肉产品价格大幅波动而带动CPI快速上调的“高通胀风险”及与工业生产PPI下降的“高通缩风险”关联性,探讨了推动猪肉价格快速上涨的机制。难控性“猪疫情”、规律性“猪周期”、投机性“猪炒作”及泛化性“外贸战”是促进肉产品价格快速上涨的“启动”、“叠加”、“内讧”及“外推”四大机制,并建议以此为机遇,充分利用新时代人们消费理念的绝对绿色健康性和恩施山区区域的相对独立分散性,克服浮躁性无序养殖心态,建立不受“猪周期”影响和少受“猪疫情”影响的“种-养-销”绿色立体生态产业链,使其与“猪炒作”脱代际,与“外贸战”失偶联,逐步形成新时代理性养殖和健康养殖与理性消费和健康消费的良性循环。     

基于智能算法的猪饲料配方优化数学模型

在多种原料配比过程中，营养指标因素复杂的实际情况及控制成本保证收益的现实需求，文章结合智能算法背景，进行猪饲料配方优化设计，建立猪饲料配方模型，采用智能算法求解饲料配方的过程，对于生猪饲料配方进行建模，同时优化出饲料配方。结果表明，智能算法的猪饲料配方优化能够解决多种原料配比以及多个营养指标复杂因素，实现快速计算和生产处理，对企业生产者、销售经营者、实际消费者具有十分重大的价值与现实意义。 [关键词]智能算法|猪饲料|配方优化|数学模型     

Improvement,identification, and target prediction for miRNAs in the porcine genome by using massive,public high-throughput sequencing data

Despite the broad variety of available microRNA (miRNA) research tools and methods, their application to the identification, annotation, and target prediction of miRNAs in nonmodel organisms is still limited. In this study, we collected nearly all public sRNA-seq data to improve the annotation for known miRNAs and identify novel miRNAs that have not been annotated in pigs (Sus scrofa). We newly annotated 210 mature sequences in known miRNAs and found that 43 of the known miRNA precursors were problematic due to redundant/missing annotations or incorrect sequences. We also predicted 811 novel miRNAs with high confidence, which was twice the current number of known miRNAs for pigs in miRBase. In addition, we proposed a correlation-based strategy to predict target genes for miRNAs by using a large amount of sRNA-seq and RNA-seq data. We found that the correlation-based strategy provided additional evidence of expression compared with traditional target prediction methods. The correlation-based strategy also identified the regulatory pairs that were controlled by nonbinding sites with a particular pattern, which provided abundant complementarity for studying the mechanism of miRNAs that regulate gene expression. In summary, our study improved the annotation of known miRNAs, identified a large number of novel miRNAs, and predicted target genes for all pig miRNAs by using massive public data. This large data-based strategy is also applicable for other nonmodel organisms with incomplete annotation information.     

绿色富硒生物猪饲料中AFB1达标生产工艺优化研究

饲料中黄曲霉毒素(AFB₁)容易超标,检出率达80%~100%,毒性大,具强致癌性,可抑制生猪免疫机能,降低动物生产性能,引起动物继发感染,还会在动物产品中残留而威胁人类健康,给生猪养殖带来经济损失,降低猪肉食品安全性。本文通过使用先进固体发酵系统设备和益生菌发酵技术,采用单因素试验和响应面中试优化,获得发酵降解猪饲料AFB₁的最佳工艺参数为硒浓度0.3 mg/kg,发酵时间12 h,量子波强度30 Hz,益生菌菌种组合CGMCC NO.17328混合CGMCC NO.15611。该工艺将猪饲料AFB₁量从63.41μg/kg降解到2.98μg/kg,降解率达到95.30%,AFB₁含量达到国家饲料安全标准。生产工艺适合养猪场低成本快速生产AFB₁达标猪饲料。     

北京家庭农场发展模式探析

家庭农场作为一种新的农业组织形式近年来在国内得到大力推广,但北京家庭农场的发展还处于试点阶段,没有形成适合的模式,对北京在试点过程中出现的规模标准缺失、劳动力缺乏、土地使用和劳动力成本高、市场运作能力弱、融资难等问题进行分析研究,借鉴国内外家庭农场发展的成功经验,提出北京家庭农场的发展要因地制宜,以特色农产品为抓手进行专业化生产,发展生态型家庭农场,进行市场化经营,同时要加强政策引导、制度保障和农场主培训等,从而形成适宜北京的家庭农场发展模式。     

集约化奶牛养殖场不同粪尿处理阶段氮素分布及氨排放特征

为促进奶牛养殖场的大气氨排放控制,形成奶牛养殖场粪便中氨排放的阻控体系,该文在冬季和夏季对内蒙古呼和浩特地区奶牛养殖场A和奶牛养殖场B的大气、牛粪和牛尿进行了采样试验分析,研究了2种奶牛养殖场不同处理工艺的氨排放特征。静态试验结果表明,奶牛养殖场A和奶牛养殖场B氨气排放浓度最高的是氧化塘处理工艺、预处理工艺,分别为冬季0.862,3.169 mg/m3,夏季2.785,2.130 mg/m3。动态试验结果表明,牛粪的氨排放系数要高于牛尿1.85倍,奶牛养殖场A和奶牛养殖场B平均排放系数分别为29.23%、49.36%。奶牛养殖场A和奶牛养殖场B总大气氨排放量分别为冬季172.69,1 101.00 kg/d,夏季284.70、1 395.32 kg/d。2种处理工艺冬季和夏季大气氨含量均满足畜禽场环境质量标准,但超过人居空气质量标准。     

非洲猪瘟对中国生猪市场和产业发展影响分析

受非洲猪瘟疫情、环保等因素影响,生猪产能快速深度下降,未来2 a猪肉供给偏紧特征明显,生猪价格快速进入新一轮上涨周期,未来养殖收益将连续3 a处于较好水平,未来2 a猪肉进口预期创新高。短期来看,非洲猪瘟影响下产销区供给过剩和供给偏紧交替出现,猪价由区域分化演变为普遍性上涨。受非洲猪瘟防控政策、产业生物安全水平提升需求和近期出台的产业支持政策等因素影响,中国生猪产业的生产和屠宰布局、流通模式、消费结构、猪肉贸易、价格周期等发生深刻变革。非洲猪瘟导致中国生猪养殖模式向适度规模转变,"公司+农户"成为主要发展模式,屠宰产能由销区向产区转移,管理和防疫成本提高,生猪产能恢复速度将较缓慢,猪肉消费加速向冷鲜肉转变,在肉类消费结构中比重将进一步下降,未来猪肉进口保持较高水平将成为常态。要有效实施非洲猪瘟分区防控、保障生猪市场稳定,需要通过加强区域化防控机制的顶层设计和立法,优化非洲猪瘟强制性扑杀补贴机制,加强基层兽医体系建设,实施"政府+企业+养殖户"联防联控,降低疫病传播风险,推动生猪产业可持续发展。     

Commuting distances to local non‐farm workplaces and out‐migration: The case of Northeast Thailand

The relationship between commuting distances and where people work has been studied for urban contexts in both developed countries and developing countries. However, few studies have examined the situation in rural areas, and none look at commuting distances to non‐farm workplaces in rural areas of developing countries. This paper investigates how commuting distance, and thus accessibility, to local non‐farm work influences non‐farm employment and out‐migration from rural villages in Northeast Thailand. The main issues examined are: (i) the distance that rural residents travel to work in local non‐farm jobs; and (ii) the influence that local non‐farm employment has on the number of outmigrants from rural villages. The study finds: (i) distance between villages and non‐farm work sites impact the number of villagers who are employed in regular wage work; (ii) beyond 20 km villagers are less likely to travel to non‐farm employment using their own means of transportation; and (iii) employment in regular wage work decreases outmigration. The findings from this study contribute to the debates over the drivers of rural out‐migration, rural livelihood changes, and agrarian changes that are taking place in Southeast Asia.