湖北省出口蛋品重金属和农药、兽药残监测及安全评价

为全面评估湖北省出口蛋品重金属和农兽残污染状况,采集了湖北省出口蛋禽备案养殖场的原料蛋及蛋制品,测定重金属汞、铅、砷、镉和农药六六六、滴滴涕等,兽药氯霉素、硝基呋喃类(呋喃唑酮、呋喃它酮、呋喃西林、呋喃妥因)、四环素类(四环素、土霉素、金霉素)、氟喹诺酮类(环丙沙星、恩诺沙星)、抗球虫药(盐霉素),非法添加物(三聚氰胺、苏丹红),环境污染物多氯联苯等含量和致病菌污染。依据国家标准对监测结果进行判定,鲜蛋样品中有5个样品检出重金属砷、铅、汞,皮蛋和咸蛋样品重金属铅、汞均有检出,砷有部分检出,所有检出样品质量均符合国家标准;兽药残留检测中有2个样品检测出氟喹诺酮类药物(1个样品环丙沙星含量6.5μg/kg,恩诺沙星140.0μg/kg;另1个样品环丙沙星含量14.8μg/kg,恩诺沙星162.7μg/kg),其他农药残留、非法添加物和微生物污染等监测项目全部合格。表明湖北出口蛋品总体质量水平高,食用安全,但也应关注蛋品中存在的重金属和兽药污染潜在威胁。     

不同消毒剂配方处理豆天蛾卵对其生长发育的影响

为探究人工养殖豆天蛾过程中卵的最佳消毒时长及筛选最优消毒剂配方,首先以38%盐酸+37%甲醛+水(0.5∶0.5∶10,V/V)为消毒剂,测定不同时长消毒处理对豆天蛾卵生长发育的影响,获得最佳消毒时长;再以此为基础,探究不同消毒剂配方(以下简称配方)处理对豆天蛾卵孵化率、25日龄幼虫存活率、体重和体长等指标的影响。结果表明,消毒30 min的豆天蛾卵孵化率(80.00%)、25日龄幼虫的存活率(59.72%)、体长(8.02 cm)及体重(8.96 g)最高,且显著高于对照。配方20(37%甲醛∶31%双氧水∶水=0.5∶0.5∶10,V/V)处理后的卵孵化率(86.67%)、25日龄幼虫存活率(66.67%)、体长(8.88 cm)和体重(10.70 g)优于其他配方,且显著高于对照,表明配方20对豆天蛾卵的消毒效果最好,为本试验筛选出的最优配方。此结果为人工养殖豆天蛾提供了一定的理论基础和技术支持。     

Heterotrophic Aurantiochytrium sp. supplementation to layer diets sustainably increases the omega-3 concentration of eggs

ABSTRACT

1. The consumption of adequate amounts of the long-chain polyunsaturated omega-3 fatty acids (n-3 LC-PUFA) has been associated with beneficial effects on human health. Eggs are commonly consumed worldwide, and their omega-3 content can be easily altered by changing the diets of laying hens and so represent an important target for enrichment.

2. In this study, the effect of supplementing laying hens with DHA-rich, Aurantiochytrium limacinum at three different inclusion levels was investigated over a 24-week period.

3. Significant increases in egg DHA concentrations were observed after four weeks and were maintained for the duration of the 24-week study. The supplemented eggs in the current study had a DHA content of 82, 101, and 129 mg/yolk when supplemented with 0.25%, 0.5% and 1% treatments, respectively, which meets the EU criteria to be considered ‘high in omega-3?.

4. Using the sustainably grown protist Aurantiochytrium limacinum to supplement layer diets increased the egg DHA concentration and decreased the n-6/n-3 ratio, improving the nutritional value of the eggs for human consumers.     

释放花绒寄甲卵对光肩星天牛幼虫的防治效果

采用木块法饲养花绒寄甲成虫,然后将其所产的卵块保存在5℃恒温条件下,以确定低温保存后花绒寄甲卵的生活力、初孵幼虫的行为学和对光肩星天牛幼虫的寄生率,并比较林间释放花绒寄甲卵与树干打孔注药(氧化乐果)防治光肩星天牛幼虫的防治效果.结果表明:低温保存49天与花绒寄甲新产卵的孵化率没有差异,花绒寄甲1龄幼虫在室内可存活1～8天、平均2.26天,爬行速度为6.5～100 cm·h-1,平均25.23 cm·h-1,室内及林间释放花绒寄甲卵后其初孵幼虫均能找到光肩星天牛幼虫并进行寄生;如果温度和湿度适宜,按照每头光肩星天牛幼虫释放15～25粒花绒寄甲卵时其寄生率可达90%;树干打孔注药与林间释放花绒寄甲卵后光肩星天牛幼虫的虫口减退率均在85%以上,两者的控制效果基本无差别.     

企业参与制定国家标准对其出口贸易规模的影响——基于上市公司数据的实证研究

运用面板数据模型,依据制造业中的1796家上市公司样本数据,考量微观层面标准对企业出口规模的影响。结果发现：企业参与制定国家标准可以有效促进出口,并且制定与国际接轨的一致标准比制定国家特有标准更能促进出口。因此,企业宜更多参与国家标准的制定,更多地推动标准层面的国际接轨。     

不同贮存期对海兰褐祖代种鸡受精蛋孵化率的影响

通过不同贮存时间对海兰褐祖代鸡孵化率影响的研究,为规模化种鸡场孵化管理提供参考.试验将来源相同的种蛋分别贮存2、3、4、5、6、7、8、9、10,1、1 d,其他贮存条件相同.同机同批孵化,分析其受精蛋孵化率.实验结果表明:贮存9 d以内的种蛋,各贮存日龄间受精蛋孵化率差异不显著(P>0.05);贮存2 d与10 d;8 d、9 d与11 d间受精蛋孵化率差异显著(P<0.05);贮存2~7 d分别与贮存10 d,贮存3~4 d分别与贮存11 d之间的受精蛋孵化率差异均达到极显著(P<0.01),保存期超过9 d后,受精蛋孵化率明显降低(P<0.01).     

茶叶出口萎缩对近代中国贸易条件的影响——基于历史计量的视角

贸易条件是衡量一国在国际市场中竞争实力和利益获得的重要指标,1867-1931年进出口贸易数据显示出中国贸易条件存在恶化趋势,同期茶叶作为近代中国最具有比较优势和代表性的出口商品,也经历了由盛及衰的变化过程。茶叶出口萎缩是近代中国贸易条件恶化的主要原因吗?本文试图通过历史计量研究来回答这一问题。研究结果表明,茶叶出口对贸易条件变化有显著的正向影响,茶叶出口萎缩确实是引发贸易条件恶化的主要原因;作者进一步将生丝出口和棉纱进口因素纳入模型,证明了这一结论的稳健性。本研究印证了比较优势在国际贸易中的重要作用,给予了近代中国贸易条件变化规律一个可信的解释,相关结论也可为当前中国农产品对外贸易形势评估和政策制定提供历史借鉴。     

古蔺河流域古蔺县段农业非点源污染综合评价

为了能准确估算古蔺河流域古蔺县境内农业非点源污染的输出负荷,确定出农田地表径流、畜禽养殖和农村居民生活污染中TN,TP输出量对水环境不同程度的影响。基于输出系数法,对研究区内三种污染源和两种污染物进行农业非点源污染综合评价,得到以下结果:研究区内农业非点源污染的输出总量为4 051.14t/a。其中TN负荷量为3 738.50t/a,TP为312.64t/a。从污染源角度分析,农田地表径流、畜禽养殖和农村居民生活三种污染源的总等标污染负荷比分别为16.57%,37.97%,45.45%。从污染物角度分析,TN,TP两种污染物的总等标污染负荷比分别为70.51%和29.49%。结果表明,农村居民生活和畜禽养殖污染是研究区内最主要的污染源,TN负荷量远大于TP为主要污染物,根据研究区的水污染情况,有针对性地提出农业非点源污染的防控措施。     

不同CO2浓度下鸡蛋呼吸仿真分析及验证

贮存环境中CO2浓度对鸡蛋呼吸作用及新鲜度变化具有重要影响,为了进一步考察在不同CO2浓度下鸡蛋呼吸释放CO2的扩散及新鲜度变化情况,该研究测定贮存在温度为25℃、相对湿度为65％、CO2体积分数分别为1.5％、3.0％、4.5％及空气(对照组)环境下鸡蛋呼吸和新鲜度,利用FLUENT软件完成不同CO2浓度下鸡蛋第1天...     

Na+ and Cl−: Leaf extrusion,retranslocation and root efflux in diplachne fusca (kallar grass) grown in NaCl

Abstract

Groups of “Kallar”; grass plants were subjected to various treatments of 100 mM NaCl simultaneously labelled with ²²Na⁺ and ³⁶Cl^?. On the basis of the specific activity, the distribution of Na and Cl^? in the tissue was followed during and after treatment, i.e. after transfer of some groups to an identical but inactive solution. Sequential collections of leaf washes showed that both Na and Cl^? were extruded at a somewhat constant rate. Leaf sheaths accumulated more Na⁺ and Cl^? than the leaf blades and the amounts of Na⁺ and Cl^? in the leaf sheaths as a percentage of their total plant content (i.e. 28% and 31%) approximated the amounts of Na and Cl^? extruded by the leaves (i.e. 23%). Moreover, almost equivalent amounts of Na⁺ (21%) and Cl^? (29%) were removed by root efflux which continued even several days after transfer of the plants to the inactive, saline solution. Part of the Na⁺ and Cl^? was retranslocated from the tops to the roots and was attributed to phloem export.

Tolerance of Kallar grass to NaCl was thus related to preventing the tissue from accumulating high concentration by extrusion of both Na⁺ and Cl^? by the leaves and their efflux by the roots in addition to an equivalent retention in the leaf sheaths.