畜禽粪便中多重耐药细菌及耐药基因的分布特征

为了解畜禽粪便中多重抗生素耐药细菌及耐药基因的污染特征,采用微生物培养的方法调查了鸡粪、猪粪中多重耐药细菌的数量,并挑取部分菌株进行16S rDNA鉴定和抗生素敏感性试验;进一步通过高通量测序技术解析多重耐药细菌的群落结构,利用高通量定量PCR对粪便中176种耐药基因的分布情况进行研究.结果表明,不同鸡粪、猪粪中对四环素、环丙沙星和庆大霉素同时耐药的多重耐药细菌比例在7.96%~12.40%;单菌株鉴定和群落结构分析均显示,可培养的多重耐药细菌主要集中在Escherichia(埃希氏杆菌属)、Acinetobacter(不动杆菌属)和Proteus(变形杆菌属)中.与未饲用抗生素的猪粪相比,猪粪样品中耐药基因的总富集倍数达到1.96×10~4~1.54×10~5倍,各类耐药基因的富集情况为:四环素类β-内酰胺类MLSB(大环内酯、林可酰胺和链阳性菌素B类)氨基糖苷类FCA(氟喹诺酮、喹诺酮、氟苯尼考、氯霉素和酰胺醇类)磺胺类万古霉素类.     

Exponential Growth, Animal Welfare, Environmental and Food Safety Impact: The Case of China’s Livestock Production

Developmental states are criticized for rapid “industrialization without enlightenment.” In the last 30 years, China’s breathtaking growth has been achieved at a high environmental and food safety cost. This article, utilizing a recent survey of China’s livestock industry, illustrates the initiating role of China’s developmental state in the exponential expansion of the country’s livestock production. The enthusiastic response of the livestock industry to the many state policy incentives has made China the world’s biggest animal farming nation. Shortage of meat and dairy supply is history. Yet, the Chinese government is facing new challenges of no less a threat to political stability. Production intensification has created a welfare crisis impacting the world’s biggest number of farm animals. The resulting food safety incidents are affecting consumer confidence and health. Untreated waste contributes to the nation’s environmental degradation. Developmental states may have a proud record of growth in the initial stage of industrialization. Their prospects for sustained development have long been questioned. China has come to an important juncture to march towards a sustained development.     

Use of a Wetland Index to Evaluate Changes in Riparian Vegetation After Livestock Exclusion 1

Abstract: A method was developed to characterize ecological integrity of riparian sites based on the abundance of hydric species. This wetland index can be calculated with species data, or with community type data as performed here. Classified riparian community types were used to describe vegetation at 14 livestock exclosures and adjacent grazed areas. Community type wetland index values were generated and used to calculate site wetland index values. It was hypothesized that removal of livestock would result in higher wetland index values because of release from herbivory and decreased physical disturbance of vegetation, streambanks, and soil. The wetland index for exclosures was about 12% higher than grazed sites; differences were statistically significant (p < 0.01) based on paired t‐tests. The increase in hydric vegetation after livestock exclusion may have contributed to the greater bank stability (p = 0.002) and smaller width‐to‐depth ratio (p = 0.005) in exclosures. Challenges were encountered in using community types to describe and compare site vegetation, which could be avoided with species data collection. The wetland index can be a tool to monitor sites over time, compare sites with similar environments, or compare sites for which environmental differences can be accounted.     

VARIATION OF STREAM STABILITY WITH STREAM TYPE AND LWESTOCK BANK DAMAGE IN NORTHERN NEVADA1

ABSTRACT: Many natural and anthropogenic factors contribute to the stability or erodibility of stream channels. Although a stream rating procedure used by more than 60 percent of the U.S. National Forests provides an estimate of overall stability, it does not identify the cause of instability or indicate corrective management. To better sort natural from livestock influences, stream stability rating indicator variables were related to stream types and levels of ungulate bank damage in a large data base for streams in northern Nevada. Stability and the range in stability varied naturally with stream type. Ungulate bank damage had different effects on different stream types and on different parts of their cross-sections. Vegetation is more important for stability on certain stream types than on other types. Streams with noncohesive sand and gravel banks are most sensitive to livestock grazing. Range managers should consider the stream type when setting local standards, writing management objectives, or determining riparian grazing strategies.     

参数选取对畜禽养殖业大气氨排放的影响:以长三角地区为例

氨对于大气细颗粒物中二次无机盐的生成具有十分重要的作用,近年来引起了国内外学者的高度关注.相对准确地定量氨排放对于深入研究二次气溶胶的理化过程、实现较好的数值模拟性能,以及开展氨排放精细化管控具有极为重要的科学意义和现实意义.已有研究表明,农业源是大气氨的主要排放源,其中,畜禽养殖业的氨排放占比最大.已有针对畜禽养殖业氨排放的研究大多采用排放系数法建立氨排放清单,然而,不同参数的选取会对研究结果造成较大差异.本文从活动水平和排放系数选取上做出了多种假设,构建了8种情景,以2017年为基准年,分别计算了长三角地区畜禽养殖业大气氨排放.结果表明,选取不同的活动水平对清单估算结果的影响最大,选取出栏量计算的结果较选取存栏量高出27.6%～34.1%.选取更细致的月均温的计算结果高出以年均温结果0.3～0.4万t.此外,清单的时空分布特征也与该两项参数密切相关,以存栏量进行估算的结果中,舟山地区排放强度最低,淮南市最高;以出栏量进行估算的结果中,丽水排放强度最低,南京最高.以月均温度估算情景中将获得更准确的月排放廓线,全年中5～9月排放量最高,冬季(12、 1和2月)排放量最小.     

基于供给—消耗关系的蒙古高原草地承载力时空变化分析

在全球气候变化与人类活动加剧的双重影响下,蒙古高原草地放牧超载与草地退化问题不断凸显。如何从畜牧业生产对草地利用强度角度揭示草地生态系统的人地关系,对草地资源可持续利用对策研究至关重要。基于生态系统供给与消耗平衡关系,利用卫星遥感数据与畜牧业统计数据,分析蒙古高原草地生态系统的生态承载状态,研究不同政策背景和资源禀赋条件下草地生态系统承载压力的区域差异特征。研究结果表明：（1）内蒙古自治区和蒙古国两地不同的政策和习俗深刻影响了牧民对草地的利用方式,使得两地畜牧业生产结构产生显著差异,内蒙古自治区牲畜类型组成区域差异性大、总量相对平稳,而蒙古国牲畜数量增加显著、牲畜类型组成区域分布更为均匀。（2）内蒙古自治区和蒙古国草地消耗量均呈现出明显的上升趋势,蒙古高原草地资源消耗总量在2014年超出了供给量,其中内蒙古自治区草地资源消耗量在2005年超出了供给量,而近年来蒙古国的草地资源消耗量也逐渐逼近供给量。（3）2000-2016年间,蒙古高原草地承载压力不断增大,整体从盈余状态变为临界超载状态,持续严重超载地区主要出现在荒漠草原地区,并逐渐向典型草原及农牧交错区推进;蒙古国自2003年起富富有余状态区逐步减少且严重超载区逐步增多,内蒙古自治区则受生态保护政策的影响呈波动性变化。通过定量分析内蒙古自治区和蒙古国草地承载状况的时空差异性,所揭示出的不同社会经济背景下畜牧业生产结构与强度的变化规律可为草地资源管理提供科学依据。     

基于污染控制的畜禽养殖场适度规模的理论分析

当前，规模化逐渐成为我国畜禽养殖业发展的主要思路，而现实中大规模养殖在带来经济效益的同时也带来了严重的环境污染。从污染控制的角度看是否存在最优养殖规模成为一个需要研究的问题。基于耕地对氮磷的承载能力、运输成本、排污费等变量构建了数理模型，探讨追求利润最大化的畜禽养殖场的最优规模问题。结果表明：在养殖场自由选择养殖规模时，出售一个养殖单位获得的经济收益越高、耕地对处理剩余物的承载能力越大，则最优养殖规模越大；而一个养殖单位的直接生产成本和粪便处理成本越高、畜禽粪便经处理后的剩余物越多、运输成本越高、排污费越高，则最优规模越小。在养殖规模既定的情况下，提高排污收费时畜禽养殖场将提高其处理剩余物的还田处置比例。最后，指出在畜禽粪便处理技术难以有效去除氮磷、对养殖场是否合理处置最终剩余物难以监管的条件下，对养殖场进行规模控制将是畜禽养殖污染控制的一个政策方向     

草原生态补奖政策对农牧民牲畜养殖规模的影响——基于生计分化的调节效应分析

实现对牲畜养殖规模的有效管控是草原生态补奖政策成败的关键。在农牧民生计分化日益加深的背景下,探讨草原生态补奖政策与生计分化对农牧民牲畜养殖规模的影响,对于完善草原生态补奖政策,实现草原生态保护与农牧民生计转换的有机结合具有重要的现实意义。本文阐释了草原生态补奖政策影响农牧民牲畜养殖规模的机理,并引入生计分化变量,基于实地调研获取的317份农牧交错区农牧民微观数据,运用最小二乘回归和分位数回归实证分析了草原生态补奖政策对农牧民牲畜养殖规模的影响以及生计分化在草原生态补奖政策影响农牧民牲畜养殖规模中的调节效应。研究结果表明:①补奖金额与牲畜养殖规模之间存在稳健的“倒U型”关系,表明补奖政策在短期内对牲畜数量的增加具有积极的促进作用,但随着补奖金额的增加,促进作用将逐渐减弱,最终趋于抑制。②根据非农牧收入占比和生计对牧业生产依赖程度的差异可将农牧民分为牧业为主型、农业为主型、均衡型、高兼型和深兼型五种类型农牧民。③农牧民生计分化对牲畜养殖规模的扩大具有抑制作用,且在草原生态补奖政策与牲畜养殖规模二者关系中具有调节作用。即在“倒U型”曲线的左侧,生计分化能够弱化草原生态补奖政策对牲畜养殖规模扩大的促进作用;在“倒U型”曲线的右侧,生计分化能够促使补奖金额对牲畜养殖规模的负向影响趋于放缓,有助于避免因补奖金额的增加引致牲畜养殖数量的锐减。根据以上结论,建议政府应进一步提高补奖标准以增强补奖弥补损失的有效性,重视发挥农牧民生计分化在牲畜养殖规模调控中的作用。     

Development of an enzyme linked immunosorbent assay for the determination of phenothiazine drugs in meat and animal feeds

In this study, 2-chlorophenothiazine was used to synthesize a hapten for production of monoclonal antibody. The obtained monoclonal antibody showed high crossreactivities to chlorpromazine, promethazine and perphenazine, and showed low crossreactivities to acepromazine and fluphenazine. After evaluation of three coating antigens, a heterologous competitive indirect enzyme linked immunosorbent assay was developed to determine the five phenothiazines in animal feeds and the residues of chlorpromazine, promethazine and perphenazine in meat. The crossreactivities to the five analytes were in a range of 2.4%–98%. The limits of detection for the five drugs in feeds were in a range of 0.1–3.0 μg g^?1, and that for chlorpromazine, promethazine and perphenazine in meat were in a range of 0.5–0.8 ng g^?1. Their recoveries from standards fortified blank samples (chicken, pork and feeds) were in a range of 74.1%–96.5% with coefficients of variation of 6.4%–15.1%. Therefore, this method could be used as a rapid screen tool to determine phenothiazine drugs in animal feeds and animal derived foods.     

人工湿地系统对含沼液畜禽废水净化效果试验研究

为了考察人工湿地处理含沼液畜禽废水的可行性,采用水平潜流人工湿地对含沼液畜禽废水进行处理实验。试验结果表明：在进水流量1.5 m3.d-1,水平潜流人工湿地系统对含沼液畜禽废水具有较好的处理效果。废水中COD、TP、TN和NH4＋-N浊度平均去除率分别为59.21%、53.80%、55.09%和55.57%.另外,通过对人工湿地沿程的污染物变化试验分析表明,人工湿地系统对污染物的降解是沿人工湿地水流方向逐渐降低的。