反刍动物饲料中农药残留研究进展

农药在农业和畜牧业生产中作为预防和治疗农作物病虫草害和料仓中卫生害虫等有害生物侵害的重要投入品,在保障农作物质优、高产及保护饲料贮存环境卫生等方面发挥着突出作用。由于其广泛应用,不可避免的残留在饲料当中。然而,反刍动物的主要饲料原料来源于农作物,致使农药进入体内的可能性增加。使用含有农药残留的饲料,可能降低动物的生长性能,严重者可危害动物健康甚至导致动物死亡,且残留在动物产品中的农药可能危害人类健康。饲料中农药残留问题应引起社会各界的关注和高度重视。本文针对反刍动物饲料原料种植过程中的使用情况,综述了饲料中农药残留情况、代谢情况及对人畜健康安全的影响,对反刍动物饲料中农药残留情况的摸底调查和风险评估具有重要的现实意义。     

苹果汁中多种有机磷农药残留的同时测定分析

随着人们对食品安全关注程度的日益提高,各国对食品中农药残留限量的要求越来越严格,其中日本“肯定列表制度”最为严格。“肯定列表制度”自实施就对我国输日浓缩苹果汁造成了较大的影响,农药残留问题成为我国浓缩苹果汁出口贸易的技术壁垒。而自2008年“甲胺磷事件”以来,我国出口浓缩果汁中甲胺磷、敌敌畏、甲拌磷、     

食品和饲料中农药残留分析方法性能标准指南

本文译自国际食品法典委员会"CAC/GL 90-2017食品和饲料中农药残留分析方法性能标准指南".该指南规定了农药残留分析方法的选择和验证原则、分析方法的性能参数、筛选方法的性能指标、定量方法的性能指标、分析物鉴定方法和确证方法的性能标准和定义等.本译文可为我国食品和饲料中农药残留分析专业人员研发和验证化学分析方法或...     

气相色谱法快速测定大米中多种农药残留

针对大米样品中残留的14种有机磷农药,通过较为简便的提取方法和实用有效地净化处理,用毛细管柱气相色谱法进行测定,方法所需时间短,干扰小,准确可靠,易于操作,回收率和检出限均能满足大米样品中残留农药检测的需要。     

蔬菜中多种有机磷农药残留气相色谱分析法

为了同时测定蔬菜中13种有机磷农药残留,利用毛细管色谱仪附火焰光度检测器进行检测.蔬菜匀浆后经乙腈提取、净化后,采用程序升温和恒流的方式进行气相色谱分析.结果表明,13种有机磷农药在22.5 min内得到很好分离.有机磷农药残留量在2～1 000 μg/kg范围内线性良好,相关系数为0.998 6～0.999 7.13种混合农药加标浓度为0.1 mg/kg时,平均回收率在73.20 %～101.23 %之间,相对标准偏差小于5 %,检出限0.01～0.05 mg/kg.该方法能一次完成蔬菜中13种有机磷农药残留的分离和测定,操作简便、灵敏.     

智能手机检测蔬菜中多种农药残留

目的 建立基于可视化蛋白芯片法智能手机同时快速检测蔬菜中3种农药残留的分析方法.方法 依次向制备好的微孔板芯片中加入50μL标准品工作液和50μL相应的纳米银标记抗体,在37℃、600 r/min下反应15 min;再加入50μL显色液进行显色并用智能手机进行拍照,Photoshop软件对图像进行反相,再用genpix...     

销售蔬菜中农药残留分析

为了解沈阳市蔬菜农药残留情况,随机采集43种蔬菜,共1180份样品,采用快速检测法和气相色谱法进行检测.43种蔬菜中,检测出农药残留超标的蔬菜有:茄子、芹菜、小白菜、菠菜和油麦菜,主要的残留农药是氧化乐果、磷胺、水胺硫磷、对硫磷、甲拌磷、三唑磷;蔬菜的农药残留受季节影响明显,冬季蔬菜农药残留最为严重;根据蔬菜种类比较发现,叶菜类蔬菜的农药残留问题明显大于果菜类和根茎类蔬菜.     

气相色谱法测定黑木耳中多种有机磷农药残留

建立黑木耳中10种有机磷类农药多残留的气相色谱(FPD检测器)快速定量检测方法.样品采用乙腈提取,PSA吸附刑净化,保留时间定性,外标法定量.结果表明10种有机磷类农药在20 min内得到良好分离;10种农药在0.01 mg/L～0.2(或0.02-0.4)mg/L浓度范围内线性关系良好,相关系数为0.996 4～0.999 8;添加水平在0.01 mg/kg和0.1(或0.02和0.20)mg/kg浓度时,平均加标回收率除敌敌畏为62.2%外,其余农药均在84.5%～127.7%之间;相对标准偏差为1.4%～22.8%;该方法准确、灵敏,可以满足黑木耳中10种有机磷农药的检测.     

廊坊市市售蔬菜中农药残留的调查分析

目的调查廊坊市市售蔬菜中农药残留的情况并进行分析。方法应用《食品中化学污染物及有害因素监测技术手册》中气相色谱法,对7大类蔬菜进行抽样检测。结果廊坊市市售不同种类蔬菜农药残留检出情况为:鳞茎类检出率82.61%,超标率8.70%;叶菜类检出率29.03%,超标率14.52%;瓜类检出率18.18%,无超标样品;茄果类检出率16.00%,超标率4.00%;芸苔属类检出率5.00%,无超标样品;豆类、根茎类和薯芋类检测结果均小于最低检出限。超标样品中超范围使用的情况占超标份数的66.7%。秋季农药残留的检出率及超标率均高于春季。结论市售蔬菜中仍存在农药残留超标的现象,应继续加强监督管理,保障食品安全。     

山东省茶叶中14种农药残留状况调查

目的：了解茶叶中农药残留状况,以便采取相应的预防策略。方法：采集潍坊、济南、烟台样品共计50份,采用气相色谱-质谱联用仪对茶叶中14种农药残留量进行检测。检测结果判定依据《食品安全国家标准食品中农药最大残留限量》（GB 2763—2021）。结果：50份茶叶样品中,检出农药残留29份,检出率为58.0%;超标样品3份,超标率为6.0%。其中6种农药有检出,联苯菊酯检出率最高,检出率为50.0%。多农药联用现象较为突出。结论：茶叶中农药残留总体超标率较低,有多农药联合使用现象,相关部门应继续采取有效的措施加强监督和检测。     

Effects of partial substitution of concentrates with maize silage in organic dairy cow rations on performance and feed efficiency

BACKGROUND: The general goal of organic dairy farming is to minimize purchased concentrate use and focus on milk production from forages. The aim of the present paper is to examine the influence of a partial substitution of purchased concentrates with home‐grown maize silage on feed intake, milk production and feed efficiency in rations for organic dairy cows. In the experimental treatment group (E), two‐thirds of average herd concentrate intake was replaced with 2.7 kg maize silage on a dry matter (DM) basis. RESULTS: In treatment E, total DM, energy and protein intake were significantly reduced compared to the control treatment group (C). Daily milk yield decreased in E by 11% and milk urea content was significantly lower. Calculated milk production from forage was significantly higher (91 versus 71%) in treatment E. Efficiency of dietary nitrogen (N) utilization (calculated as milk N as a percentage of N intake) was slightly improved in E and protein and energy balance (calculated as intake as a percentage of requirements) were closer to zero than in C. CONCLUSION: The present study indicates a potential to reduce levels of concentrates and substitute them with maize silage in organic dairy cow rations at least in the second half of lactation. Copyright © 2007 Society of Chemical Industry     

Using brown midrib 6 dwarf forage sorghum silage and fall-grown oat silage in lactating dairy cow rations

Double cropping and increasing crop diversity could improve dairy farm economic and environmental sustainability. In this experiment, corn silage was partially replaced with 2 alternative forages, brown midrib-6 brachytic dwarf forage sorghum (Sorghum bicolor) or fall-grown oat (Avena sativa) silage, in the diet of lactating dairy cows. We investigated the effect on dry matter (DM) intake, milk yield (MY), milk components and fatty acid profile, apparent total-tract nutrient digestibility, N utilization, enteric methane emissions, and income over feed cost. We analyzed the in situ DM and neutral detergent fiber disappearance of the alternative forages versus corn silage and alfalfa haylage. Sorghum was grown in the summer and harvested in the milk stage. Oats were grown in the fall and harvested in the boot stage. Compared with corn silage, neutral detergent fiber and acid detergent fiber concentrations were higher in the alternative forages. Lignin content was highest for sorghum silage and similar for corn silage and oat silage. The alternative forages had less than 1% starch compared with the approximately 35% starch in the corn silage. Ruminal in situ DM effective degradability was similar, although statistically different, for corn silage and oat silage, but lower for sorghum silage. Diets with the alternative forages were fed in a replicated 3 × 3 Latin square design experiment with three 28-d periods and 12 Holstein cows. The control diet contained 44% (DM basis) corn silage. In the other 2 diets, sorghum or oat silages were included at 10% of dietary DM, replacing corn silage. Sorghum silage inclusion decreased DM intake, MY, and milk protein content but increased milk fat and maintained energy-corrected MY similar to the control. Oat silage had no effect on DM intake, MY, or milk components compared to the control. The oat silage diet increased apparent total-tract digestibility of dietary nutrients, except starch, whereas the sorghum diet slightly decreased DM, organic matter, crude protein, and starch digestibility. Cows consuming the oat silage diet had higher milk urea N and urinary urea N concentrations. Milk N efficiency was decreased by the sorghum diet. Diet did not affect enteric methane or carbon dioxide emissions. This study shows that oat silage can partially replace corn silage at 10% of the diet DM with no effect on MY. Brown midrib sorghum silage harvested at the milk stage with <1% starch may decrease DM intake and MY in dairy cows.     

Effects of dietary forage level and monensin on lactation performance, digestibility and fecal excretion of nutrients, and efficiency of feed nitrogen utilization of Holstein dairy cows

Two experiments (Exp. 1 and 2) were conducted using a 4 × 4 Latin square design with 2 replications (n = 8) to evaluate effects of feeding Holstein dairy cows a total mixed ration containing 50 or 60% of ration dry matter (DM) from forages with or without supplementation of monensin. In Exp. 1, alfalfa silage (AS) was used as the major forage (55% forage DM), and corn silage (CS; 45% forage DM) was used to make up the rest of the forage portion of diets (55AS:45CS). In Exp. 2, CS was used as the major forage (70% forage DM) and alfalfa hay (AH; 30% forage DM) was used to make up the rest of the forage portion of diets (70CS:30AH). Experimental diets were arranged in a 2 × 2 factorial with 50 or 60% ration DM from forages and monensin supplemented at 0 or 300 mg/cow daily. In Exp. 1 (55AS:45CS), feeding 60% forage diets decreased DM intake (DMI; 27.3 vs. 29.6 kg/d) but maintained the same levels of milk (45.8 vs. 47.0 kg/d) compared with 50% forage diets. The efficiency of converting feed to milk or 3.5% fat-corrected milk was greater for cows fed 60% compared with 50% forage diets (1.7 vs. 1.6 kg milk or 3.5% fat-corrected milk/kg of DMI, respectively). Increasing dietary forage level from 50 to 60% of ration DM increased milk fat percentage (3.4 to 3.5%); however, adding monensin to the 60% forage diet inhibited the increase in milk fat percentage. Feeding 60% forage diets decreased feed cost, but this decrease ($0.5/head per day) in feed cost did not affect income over feed cost. Feeding 60% forage diets decreased fecal excretion of DM (10.6 to 9.6 kg/d) and nitrogen (N; 354 to 324 g/d) and improved apparent digestibility of neutral detergent fiber from 43 to 49% and apparent efficiency of feed N utilization from 32.3 to 35.9% compared with 50% forage diets. In Exp. 2 (70CS:30AH), feeding 60% forage diets decreased DMI from 29.6 to 28.2 kg but maintained the same level of milk (41.1 vs. 40.8 kg/d) and therefore increased the efficiency of converting feed to milk (1.46 vs. 1.38 kg milk/kg DMI) compared with 50% forage diets. Daily feed cost for feeding 60% forage diets was $0.3/head lower than for the 50% forage diets. Fecal excretion of DM (10.3 vs. 11.5 kg/d) was lower and fecal excretion of N (299 vs. 328 g/d) tended to be lower for 60% compared with 50% forage diets. Results from these 2 experiments suggest that a 60% forage diet consisting of either AS or CS as the major forage can be fed to high producing Holstein dairy cows without affecting milk production while improving or maintaining the efficiency of converting feed to milk and the apparent efficiency of utilization of feed N. Cows receiving a 60% forage diet had a similar or improved digestibility of nutrients with a similar or reduced fecal excretion of nutrients. Effects of monensin under the conditions of the current experiments were minimal.     

Enhancing in vitro degradation of alfalfa hay and corn silage using feed enzymes

A series of in vitro fermentation experiments was performed to assess the effects of 4 feed enzyme products (FE) that varied in enzymatic activities on the degradation of alfalfa hay and corn silage. The FE contained a range of endoglucanase, exoglucanase, xylanase, and protease activities, and a range of dose rates (DR) was used. The objective of the study was to identify effective formulations and optimum DR, and to establish if combining FE would further improve fiber degradation. For alfalfa hay, quadratic increases in gas production and degradation of dry matter (DM) and fiber were observed for all FE, with maximum responses at low to medium DR. For corn silage, none of the FE increased gas production or DM degradation, but all FE increased NDF degradation, with optimum DR in the low to medium range. The proteolytic enzyme papain improved fiber degradation of alfalfa hay and corn silage in a manner similar to that observed for polysaccharidase FE. Among the polysaccharidase FE, added activities of endoglucanase and exoglucanase were positively correlated with improvement in neutral detergent fiber (NDF) degradability of corn silage, whereas only added endoglucanase activity tended to be correlated with improvement in NDF degradability of alfalfa hay. Combining effective polysaccharidase FE further improved fiber degradation of both forages, with greater improvements for corn silage. Combining polysaccharidase and proteolytic FE further improved NDF degradation of corn silage, but not alfalfa hay. Combination treatments generally resulted in additive effects with increases in fiber degradation equal to the sum of the improvements for the individual enzyme components. Improved fiber degradation of corn silage was associated with decreased acetate to propionate ratios. Enzyme products that improve in vitro degradation of forages may have the potential to improve lactational performance of dairy cows.     

A meta-analysis of feed digestion in dairy cows. 2. The effects of feeding level and diet composition on digestibility

A meta-analysis based on published experiments with lactating dairy cows fed mainly grass silage-based diets was conducted to study the effects of intake, diet composition, and digestibility at a maintenance level of feeding on the apparent total diet digestibility. A data set that included a total of 497 dietary treatment means from 92 studies was collected and analyzed using mixed model regression analysis with a random study effect. Diet organic matter digestibility (OMD) in dairy cows at a production level (OMD_p) was positively associated with OMD at maintenance (OMD_m), but the slope was less than 1 (0.69). Diet OMD_p decreased as feed intake increased, and diets with high OMD_m exhibited greater depressions in digestibility with increased intake than did diets with low OMD_m. Digestibility of organic matter and neutral detergent fiber (NDF) increased as dietary crude protein concentration increased, whereas increased concentrate fat decreased digestibility. Replacement of grass silage with whole-crop cereal silage was associated with a quadratic decrease in diet digestibility. Metabolic fecal output, defined as fecal organic matter minus NDF, averaged 95.8 (SE = 0.65) g/kg of dry matter intake, and it was not influenced by intake or diet composition. Variation in OMD_p in cows fed grass silage-based diets was therefore attributable to variation in dietary NDF concentration and NDF digestibility. Depression in digestibility of organic matter with increased intake was less than predicted by the National Research Council and Cornell Net Carbohydrate and Protein systems. The following 2-parameter model indicates that the difference between OMD estimated in sheep fed at maintenance compared with dairy cows at production level is related both to dry matter intake and digestibility at maintenance level: OMD_p = 257 (±43) + 0.685 (±0.054) × OMD_m (g/kg of dry matter) - 2.6 (±0.44) × dry matter intake (kg/d); adjusted residual mean square error = 8.4 g/kg. It was concluded that diet digestibility in dairy cows can be predicted accurately and precisely from digestibility estimated at maintenance intake in sheep by using regression models including animal and dietary factors.     

二氧化氯对原料果农药残留的清除作用研究

通过研究、分析二氧化氯对原料果农药残留（如甲胺磷、甲基对硫磷）的分解作用，依据原料果的清洗程序，设计了加药工序及清洗工艺，并对控制点（一榨浊汁）的农药残留进行了检测。测试结果表明：在原料果清洗的适当环节加入50～75mg／kg的二氧化氯，可有效地分解农药残留．     

Nutritive value of maize silage in relation to dairy cow performance and milk quality

Maize silage has become the major forage component in the ration of dairy cows over the last few decades. This review provides information on the mean content and variability in chemical composition, fatty acid (FA) profile and ensiling quality of maize silages, and discusses the major factors which cause these variations. In addition, the effect of the broad range in chemical composition of maize silages on the total tract digestibility of dietary nutrients, milk production and milk composition of dairy cows is quantified and discussed. Finally, the optimum inclusion level of maize silage in the ration of dairy cows for milk production and composition is reviewed. The data showed that the nutritive value of maize silages is highly variable and that most of this variation is caused by large differences in maturity at harvest. Maize silages ensiled at a very early stage (dry matter (DM) < 250 g kg^?1) were particularly low in starch content and starch/neutral detergent fibre (NDF) ratio, and resulted in a lower DM intake (DMI), milk yield and milk protein content. The DMI, milk yield and milk protein content increased with advancing maturity, reaching an optimum level for maize silages ensiled at DM contents of 300–350 g kg^?1, and then declined slightly at further maturity beyond 350 g kg^?1. The increases in milk (R² = 0.599) and protein (R² = 0.605) yields with maturity of maize silages were positively related to the increase in starch/NDF ratio of the maize silages. On average, the inclusion of maize silage in grass silage‐based diets improved the forage DMI by 2 kg d^?1, milk yield by 1.9 kg d^?1 and milk protein content by 1.2 g kg^?1. Further comparisons showed that, in terms of milk and milk constituent yields, the optimum grass/maize silage ratio depends on the quality of both the grass and maize silages. Replacement of grass silage with maize silage in the ration, as well as an increasing maturity of the maize silages, altered the milk FA profile of the dairy cows, notably, the concentration of the cis‐unsaturated FAs, C18:3n‐3 and n‐3/n‐6 ratio decreased in milk fat. Despite variation in nutritive value, maize silage is rich in metabolizable energy and supports higher DMI and milk yield. Harvesting maize silages at a DM content between 300 and 350 g kg^?1 and feeding in combination with grass silage results in a higher milk yield of dairy cows. © 2014 Society of Chemical Industry     

GC在农药残留检测中的问题及对策

GC是现今检测农药残留的广泛应用方法,针对其在检测过程中所碰到的一系列常见问题,结合实际操作经验,给出相应的解决对策。主要涉及样品的前处理、气相色谱仪的维护保养、气相色谱仪检测条件的设置等诸多方面。     

Effects of essential oils on digestion, ruminal fermentation, rumen microbial populations, milk production, and milk composition in dairy cows fed alfalfa silage or corn silage

Four Holstein cows fitted with ruminal cannulas were used in a 4 × 4 Latin square design (28-d periods) with a 2 × 2 factorial arrangement of treatments to investigate the effects of addition of a specific mixture of essential oil compounds (MEO; 0 vs. 750 mg/d) and silage source [alfalfa silage (AS) vs. corn silage (CS)] on digestion, ruminal fermentation, rumen microbial populations, milk production, and milk composition. Total mixed rations containing either AS or CS as the sole forage source were balanced to be isocaloric and isonitrogenous. In general, no interactions between MEO addition and silage source were observed. Except for ruminal pH and milk lactose content, which were increased by MEO supplementation, no changes attributable to the administration of MEO were observed for feed intake, nutrient digestibility, end-products of ruminal fermentation, microbial counts, and milk performance. Dry matter intake and milk production were not affected by replacing AS with CS in the diet. However, cows fed CS-based diets produced milk with lower fat and higher protein and urea N concentrations than cows fed AS-based diets. Replacing AS with CS increased the concentration of NH₃-N and reduced the acetate-to-propionate ratio in ruminal fluid. Total viable bacteria, cellulolytic bacteria, and protozoa were not influenced by MEO supplementation, but the total viable bacteria count was higher with CS- than with AS-based diets. The apparent digestibility of crude protein did not differ between the AS and CS treatments, but digestibilities of neutral detergent fiber and acid detergent fiber were lower when cows were fed CS-based diets than when they were fed AS-based diets. Duodenal bacterial N flow, estimated using urinary purine derivatives and the amount of N retained, increased in cows fed CS-based diets compared with those fed AS-based diets. Feeding cows AS increased the milk fat contents of cis-9, trans-11 18:2 (conjugated linoleic acid) and 18:3 (n-3 fatty acid) compared with feeding cows CS. Results from this study showed limited effects of MEO supplementation on nutrient utilization, ruminal fermentation, and milk performance when cows were fed diets containing either AS or CS as the sole forage source.