氟苯尼考在产蛋前期鸡蛋中的残留规律及膳食暴露评估

目的：为了探索开产前蛋鸡使用氟苯尼考后产蛋前期鸡蛋中氟苯尼考的残留规律,评估氟苯尼考对鸡蛋安全性的影响,评价其食用风险。方法：蛋鸡开产前不同时间预防性投喂氟苯尼考后测定鸡蛋中氟苯尼考残留量。结果：给药期间鸡蛋中氟苯尼考和氟苯尼考胺的残留量逐渐升高可达到峰值,或停药后1 d达到峰值,最大残留量出现在第4组为515.86 μg/kg。停药后5 d,鸡蛋中氟苯尼考和氟苯尼考胺的残留总量基本小于100 μg/kg。随着蛋鸡日龄的增长,产蛋率逐渐升高,停药后10~14 d鸡蛋中氟苯尼考和氟苯尼考胺残留量低于检出限。结论：对照实验各组鸡蛋中的检出是氟苯尼考和氟苯尼考胺的浓度总和,开产前23 d使用氟苯尼考,开产后所产鸡蛋对成人和婴儿都是安全的。     

恩诺沙星、氟苯尼考和泰万菌素在鸡蛋中残留消除规律研究

目的 评估恩诺沙星、氟苯尼考和泰万菌素在鸡蛋中的残留消除规律。方法 将80羽高产海兰褐蛋鸡随机等分成4组, 对照组饲喂基础日粮, 恩诺沙星组、氟苯尼考组和泰万菌素组分别经混饲给予相应药物, 每日1次, 连续给药5 d, 停药19 d, 检测各枚鸡蛋中相应药物及其主要代谢产物的残留量。结果 恩诺沙星及其主要代谢产物环丙沙星与氟苯尼考及其主要代谢产物氟苯尼考胺可迅速残留于鸡蛋中, 残留物分别以恩诺沙星原型和氟苯尼考原型为主, 且其残留蓄积期都超过19 d。泰万菌素及其主要代谢产物3-乙酰胺基泰万菌素在鸡蛋中的残留总量低于最大允许残留限量, 且平均残留蓄积期为7 d, 3-乙酰胺基泰万菌素占总残留量的50%以上。结论 恩诺沙星和氟苯尼考在海兰褐品系鸡蛋中残留消除周期超过19 d, 在对后备蛋鸡、肉蛋兼用鸡给药时需严格控制用法用量。在适用情况下, 可优先选择平均残留消除周期相对较短的泰万菌素。     

土霉素、环丙沙星、恩诺沙星在鲫鱼体内残留及消除规律的初步研究

在25±2℃水温条件下,研究土霉素、环丙沙星和恩诺沙星在鲫鱼体内的残留及消除规律.药物在鲫鱼肌肉中的残留用甲醇 水(2 8,pH5.30)提取,反相高效液相色谱法检测,最低检测限可达0.0105mg/kg,平均回收率在80%～95%.研究结果表明:在给定的给药条件下,停药5d后鱼体肌肉的药物浓度达到最大值,停药15d后土霉素和恩诺沙星的残留量降至最大残留限量(MRLs)以下,而环丙沙星的残留仍略高于其MRLs.     

氟苯尼考在鸡蛋和蛋鸡组织中的残留规律及预测模型建立

氟苯尼考是一种被广泛应用于动物养殖过程中的抗生素药物，可能残留于畜产品中，被人类长期食用会对机体造成耐药性、免疫抑制等不良影响。本实验旨在探讨蛋鸡摄入不同剂量氟苯尼考后，鸡蛋及各组织中氟苯尼考及其代谢产物氟苯尼考胺的清除规律，建立残留预测数学模型。本实验选取处于产蛋高峰期的罗曼粉壳蛋鸡250 只（350 日龄、体质量（1.97±0.07）kg），随机分为5 组，每组50 只，分别给予氟苯尼考0（对照）、30、60、120、240 mg/（kg mb·d），连续给药5 d。采用液相色谱-串联质谱法测定不同休药时间点蛋黄、蛋清、卵黄、肌肉、肝脏中氟苯尼考及其代谢产物氟苯尼考胺的残留含量。结果表明：休药1～3 d时，240 mg/（kg mb·d）剂量组蛋鸡产蛋率与其他处理组相比显著降低（P＜0.05），休药4 d后恢复至对照组水平；氟苯尼考及其代谢产物氟苯尼考胺在产蛋鸡组织中残留含量分布：蛋黄＞卵黄＞蛋清＞肝脏＞肌肉；不同组织残留氟苯尼考及氟苯尼消除所需休药时间：肝脏＜肌肉＜蛋清＜蛋黄＜卵黄；氟苯尼考给药剂量和休药时间对残留含量影响高度显著（P＜0.001），且给药剂量与休药时间互作效应高度显著（P＜0.001）。休药时间、给药剂量和残留含量之间呈现二元二次回归关系（P＜0.001）。为达到《中国兽药典（2015年版）》所规定的氟苯尼考给药剂量范围（40～60 mg/（kg mb·d）），肌肉等组织需休药1 d、蛋清蛋黄需休药13 d、卵黄需休药21 d。     

不同水温条件下恩诺沙星及其代谢物在俄罗斯鲟体内的代谢及消除规律

目的探究12～15℃低水温及18～21℃高水温条件下,恩诺沙星在俄罗斯锝体内的代谢及消除规律。方法以60 mg/(kg·bw)剂量连续5 d对体重为(750±50) g的健康俄罗斯锝灌服恩诺沙星,并于停药后1～140 d内连续采集血浆、肌肉、肝脏、肾脏、皮肤及鳃样品,经高效液相色谱-串联质谱法测定其中恩诺沙星及其代谢产物环丙沙星含量,研究连续5 d给药后恩诺沙星及其代谢产物环丙沙星在俄罗斯鲟体内的代谢及消除规律,得出不同温度条件下的休药期。结果在2种水温条件下,恩诺沙星在俄罗斯锝体内各组织中的达峰时间t_(max)均为1 d;夏季达峰浓度C_(max)小于冬季C_(max);药浓度-时间曲线下总面积AUC随温度升高而增大;药物自体内消除的清除率Cl_(z/f)及消除半衰期T_(1/2z)数据均表明,随温度升高药物清除速度加快。恩诺沙星在俄罗斯锝体内代谢产物为环丙沙星,其消除趋势与恩诺沙星大致相同。结论以皮肤和肌肉作为可食性组织,以恩诺沙星和环丙沙星总量降至0.1 mg/kg为标准,连续5 d以60 mg/(kg·bw)对俄罗斯锝口灌恩诺沙星后,建议冬季低温条件下休药期为124.2 d,夏季高温条件下休药期为112.9 d。     

恩诺沙星及其代谢物在俄罗斯鲟多组织中的 代谢及消除研究

目的研究恩诺沙星及其代谢产物环丙沙星在俄罗斯鲟中的代谢及消除规律,制定恩诺沙星在俄罗斯鲟体内的休药期。方法在水温12～15℃条件下,以60 mg/(kg?bw)剂量对体重为(750±50) g的健康俄罗斯鲟灌服恩诺沙星,灌服后的0～3360 h内不间断采样,使用高效液相色谱-串联质谱仪测定各组织内恩诺沙星及其代谢产物含量。结果灌药后,恩诺沙星在俄罗斯鲟鳃、血浆、肌肉、肝脏、肾脏、皮肤中达峰时间Tmax分别为0.25、9、12、12、18、24 h;肾脏、肝脏、皮肤、肌肉、鳃、血浆达峰浓度Cmax分别为31.863、23.435、21.434、18.640、10.342、2.599 mg/kg;消除半衰期以皮肤最大t1/2为394.431 h、血浆最小为129.6 h。鳃中药物浓度有2个峰值,第1次达峰时,血浆中药物浓度远低于鳃,推测与受试鱼进食习惯或组织结构有关。代谢产物环丙沙星代谢及消除趋势与恩诺沙星大致相同,血浆最早达峰, Tmax为12 h,达峰浓度以肝脏和肾脏较高,Cmax分别为6.876mg/kg和5.648mg/kg。结论从水产品质量安全角度应用本研究结果:以皮肤和肌肉作为可食性组织,恩诺沙星和环丙沙星残留总量不超过0.1 mg/kg至少需要100 d。     

抗生素在鸡蛋及鸡体组织中的代谢研究

目的 探究蛋鸡养殖业中广泛使用且在市场鸡蛋中检出频率较高的3种抗生素：氟苯尼考(florfenicol, FF)、恩诺沙星(enrofloxacin, ENR)、多西环素(doxycycline, DOX)在鸡蛋及鸡体组织中的代谢情况。方法 试验选取健康的103日龄育成鸡和300日龄产蛋鸡各105只,均分成7组,分别为FF低、FF高、ENR低、ENR高、DOX低、DOX高以及对照组。以肌肉注射的方式连续给药5 d,“低”代表说明书正常用量,“高”代表正常用量的一倍,对鸡只接受抗生素后一段时间内所产鸡蛋及鸡体组织中药物残留情况进行检测分析。结果 103日龄育成鸡使用抗生素后,至鸡只130日龄时所产鸡蛋中能检测到氟苯尼考残留,150日龄时所产鸡蛋中能检测到恩诺沙星和多西环素残留,3种抗生素还造成蛋鸡肝脏组织表面不同程度的出血和坏死;300日龄产蛋鸡注射抗生素后,氟苯尼考在蛋清、蛋黄中消除的时间分别为10 d、12 d。恩诺沙星在蛋清、蛋黄中消除的时间均为9 d。多西环素在蛋清、蛋黄中消除的时间均为25 d。结论 蛋鸡育成后期使用抗生素会对初产鸡蛋及鸡的肝脏组织造成一定影响,针对我国市场动物源性食品中频繁检出抗生素等问题,建议关注蛋鸡后备期抗生素的使用,不断强化市场监督机制和准入门槛,保障鸡蛋安全,维护人体健康。     

恩诺沙星注射液在猪体内残留消除规律研究

目的研究恩诺沙星注射液在猪体内的残留消除规律。方法本实验采用30头约50 kg重长白猪,随机分为2组,给药组25头,对照组5头。给药组用药量为每次2.5mg恩诺沙星/kg,每日1次,连用3d(1个疗程),使用1个疗程,对照组不给任何抗菌药物,与给药组同环境饲养。在最后一次给药6 h、24 h(1 d)、72 h(3 d)、120 h(5 d)、168 h(7 d)时采集肉、肝、肾、脂肪样本,经液相色谱-串联质谱法(liquid chromatography-tandem mass spectrometry, LC-MS/MS)测定组织中的恩诺沙星及其代谢物环丙沙星残留量之和,并利用WT1.4软件计算休药期。结果恩诺沙星注射液在猪肉中的休药期为3.17 d;在肾脏中的休药期为3.75 d;在肝脏中的休药期为8.18 d;在脂肪总的休药期为4.09 d。结论为保证兽药使用安全、食品安全和消费者健康,推荐恩诺沙星注射液在猪体内的休药期为9 d。     

恩诺沙星在余干乌鸡不同组织中的残留消除规律研究

目的 研究恩诺沙星可溶性粉在余干乌鸡各组织内的残留消除规律。方法 88只110d龄健康余干乌鸡,随机分为11组,以0.75 g/L饮水连续给药5 d。停药后第0.16、1、3、5、7、9、20、30、40 d采集肌肉、肝脏、肾脏、皮脂样本,经液相色谱-串联质谱法测定组织中恩诺沙星和环丙沙星残留量,计算药物代谢半衰期,并利用WT1.4软件计算恩诺沙星在余干乌鸡体内的休药期。结果 恩诺沙星在余干乌鸡体内的半衰期和休药期均长于普通肉鸡。恩诺沙星可溶性粉在余干乌鸡肌肉、肝脏、肾脏及皮脂中的休药期分别是110、64、67和208 d。结论 为保证乌鸡产品质量安全和消费者健康,推荐恩诺沙星可溶性粉在余干乌鸡体内的休药期应大于210 d。     

不同鸡种及不同产蛋周龄鸡蛋营养成分比较分析

目的比较不同鸡种及不同产蛋阶段所产鸡蛋营养成分的差异。方法在相同条件下饲养海兰褐鸡、苏禽青壳鸡、仿土蛋鸡,比较产蛋前期(21周)、中期(43周)、后期(67周)所产鸡蛋的营养成分及矿物元素含量。结果不同鸡种所产鸡蛋的粗蛋白含量差异不显著(P0.05);海兰褐鸡蛋的干物质、粗脂肪、胆固醇、磷脂、磷、铁、硒等含量均显著小于仿土蛋鸡蛋和苏禽青壳蛋(P0.05),仿土蛋鸡蛋和苏禽青壳蛋二者间差异不显著(P0.05)。产蛋前期鸡蛋的干物质含量显著低于产蛋中、后期(P0.05);仿土蛋鸡和苏禽青壳产蛋前期鸡蛋的粗脂肪含量显著低于产蛋中、后期(P0.05);产蛋前期鸡蛋的胆固醇和磷脂含量显著高于产蛋后期(P0.05),产蛋后期显著高于产蛋中期(P0.05),不同产蛋阶段鸡蛋的粗蛋白、磷、铁、铜和硒含量差异匀不显著(P0.05);不同鸡种在不同产蛋阶段所产鸡蛋的钙、镁、锌、锰等含量存在一定差异。结论青壳蛋和仿土鸡蛋营养成分要优于海兰褐鸡蛋,初产蛋除了磷脂含量较高,其他营养成分基本相同。     

Distribution and elimination of levamisole in eggs and tissues after oral administration to laying hens,determined by LC-MS/MS

Levamisole was administered to laying hens, and concentrations in eggs and tissues (thigh muscle, breast muscle, liver and kidney) were determined by a newly developed liquid chromatography tandem mass spectrometry method, which allowed trace level quantification of levamisole. The adopted analytical method showed good sensitivity, repeatability and percentage of recovery from spiked matrices. Maximum concentrations of levamisole were found on the first day after the administration (531.1 μg/kg in liver, 164.3 μg/kg in egg yolk, 130.7 μg/kg in kidney, 78.0 μg/kg in breast muscle, 70.7 μg/kg in thigh muscle and 64.0 μg/kg in egg white), after which there is a decline. The compound was rapidly eliminated from eggs, with a half-life of 1.3 days. Elimination appeared to be slower in thigh muscle (3.5 days), breast muscle (3.4 days) and liver (3.3 days). According to this experiment, the levamisole withdrawal periods calculated for eggs, liver, kidney, breast muscle and thigh muscle in laying hens were 14.1, 6.1, >4.0, 14.5 and 13.0 days, respectively. The longest time for levamisole residues to be completely released from tissues was seen in liver samples (37.4 days), followed by thigh muscle, breast muscle and kidney. Elimination from eggs was fastest (16.4 days for levamisole residues to drop below the method quantification limit).     

The residue levels of narasin in eggs of laying hens fed with unmedicated and medicated feed

Laying hens were fed contaminated feed containing narasin 2.5 mg/kg for 21 days followed by a 7 day withdrawal period, hens in the control group were fed unmedicated feed. Eggs were collected during trial days 0, 3, 7, 14, 21 and after the withdrawal period of 7 days. The concentration of narasin in yolks and egg whites was analyzed by a liquid chromatography-mass spectrometry method. Narasin was found to accumulate in yolks, where the narasin concentration increased during the treatment. The concentration of narasin varied from 5.9 to 13.8 microg/kg (mean 10.6 microg/kg) in yolks after 21 day feeding periods. The concentrations of narasin ranged from < 0.9 to 1.4 microg/kg after the withdrawal period. Narasin residues were not found in egg whites of the laying hens fed contaminated feed nor in either yolks or egg whites of the laying hens fed unmedicated feed. The effect of cooking was also tested on the amount of narasin residues in eggs. Cooking for 10 min did not significantly influence the narasin residues in eggs. Traces of lasalocid were also found in the yolks. The traces of lasalocid are attributable to an accidental contamination of the feed during its manufacture.     

Residues of sulfadiazine and doxycycline in egg matrices due to cross-contamination in the feed of laying hens and the possible correlation with physicochemical, pharmacokinetic and physiological parameters

In the poultry industry, the widespread use of veterinary drugs such as antimicrobial compounds may lead to the presence of residues in whole eggs, egg white and egg yolk. During this study, laying hens received experimental feed containing sulfadiazine or doxycycline at cross-contamination levels of 2.5%, 5% and 10% of the therapeutic concentration. Since the therapeutic dose is 250 mg kg(-1) for both substances, cross-contamination concentrations in the feed of 6.25, 12.5 and 25 mg kg(-1) were expected. Whole egg, egg white and egg yolk samples were collected during the treatment and depletion period and were analysed via liquid chromatography-tandem mass spectrometry. For both drugs, a plateau phase was reached within 3-5 days and residue concentrations were detected in all egg matrices. For the 10% cross-contamination group, residual sulfadiazine concentrations of 208, 299 and 60 μg kg(-1) and residual doxycycline concentrations of 455, 332, 206 μg kg(-1) were detected in whole egg, egg white and egg yolk on day 13 of the treatment period, respectively. Both sulfadiazine and doxycycline had higher concentrations in egg white than in egg yolk, but the egg white-egg yolk ratio was higher for sulfadiazine than for doxycycline. As neither drug is allowed in Belgium for use in laying hens, residues may pose food safety concerns.     

Combined effect of antibiotic and competitive exclusion treatment on Salmonella enteritidis fecal shedding in molted laying hens

Salmonella Enteritidis is an important pathogen for the layer industry, primarily because of its ability to infect hens and ultimately contaminate egg contents. Studies have shown that stress situations, such as flock recycling (induced molting), can increase Salmonella Enteritidis problems in the flock. The present study examined the effect of antibiotic treatment and competitive exclusion (CE) on Salmonella Enteritidis shedding in the period following molt and 14-day feed withdrawal. In two separate trials, 48 birds after molt and feed withdrawal were divided into one group that was treated for 10 days with enrofloxacin in water followed by administration of CE culture and a group that was left untreated. Salmonella Enteritidis shedding was significantly reduced in the antibiotic-CE group. The Salmonella Enteritidis shedding rate was 33 and 25% in untreated birds versus 4 and 0% in the enrofloxacin-CE group on the two test days. These results indicate that treatment of Salmonella Enteritidis-positive laying hens after molting with enrofloxacin and CE culture can substantially reduce Salmonella Enteritidis problems due to molting and would be a possible alternative to diverting eggs for pasteurization or slaughtering the infected flock. Possible development of bacterial resistance in conjunction with antibiotic use is also discussed.     

Doxycycline depletion and residues in eggs after oral administration to laying hens

The depletion of doxycycline (DC) residues in eggs was determined after oral drug administration by drinking water to laying hens. The antibiotic was supplied to birds for 5 consecutive days and the eggs were collected during medication and 18 days after withdrawal. DC residues were determined by LC-MS/MS. DC was isolated from eggs with a solution of 0.02 M of oxalic acid (pH 4), 0.1 M Na₂EDTA and acetonitrile. The limit of detection (LOD) and limit of quantification (LOQ) of the method were 2 and 5 µg kg^–1, respectively. Analyses were performed on whole egg, egg white and yolk separately. DC was detectable 24 h after the beginning of administration. The concentration of antibiotic increased daily, resulting in the highest DC concentration in whole eggs at the first day of the withdrawal period. Thirteen days after withdrawal, the content of DC in whole eggs was below the LOQ of the method. However, some differences were found in the depletion curve of DC between egg white and yolk. Residues of DC in egg white were much higher during treatment and 1 day after withdrawal, but later the concentration in egg white decreased fairly rapidly and a higher DC content in egg yolk was observed. The depletion period was shorter for egg white than for yolk, and DC was detected in the egg white until 12 days after withdrawal and 2 days more in egg yolk than in white. DC reached a peak faster in egg white, but the residues were detectable for longer period in the yolk.     

An automated HPLC determination of meticlorpindol in eggs with UV absorbance detection, using on-line dialysis and pre-concentration as sample clean-up; occurrence in and carry over to eggs

A fully automated HPLC determination of the coccidiostat meticlorpindol in whole egg, egg white and yolk is described. The sample homogenate is dialysed on-line against water. The dialysate is concentrated on-line on a short reversed-phase (RP) column. The contents of this column are transferred to the reversed-phase analytical column by means of the mobile phase. Meticlorpindol is detected using an absorbance detector at 270 nm. Linear calibration graphs are obtained in the range 40-900 ng/g in whole egg and egg white (detection limit 10 ng/g) and 80-1800 ng/g in yolk (detection limit 20 ng/g). Out of 111 commercially obtained egg samples 12 contained meticlorpindol with levels varying from 10 to 433 ng/g. A group of laying hens, kept in cages, received 10 mg/kg of Lerbek (meticlorpindol and methylbenzoquate; Dow Chemical) in the feed for 10 days. Meticlorpindol residues in the eggs rose to a level of 622 ng/g. Meticlorpindol was found in the eggs until 6 days after withdrawal of the medicated feed. Another group received 110 mg/kg in the feed. Meticlorpindol residues rose to levels of 4480 ng/g in the eggs, 5880 ng/g in the egg white and 2660 ng/g in the yolk. Meticlorpindol was found in the eggs and the egg white until 14 days and in the yolk until 8 days after withdrawal of the medicated feed.     

Validation of HPLC method of analysis of tetracycline residues in eggs and broiler meat and its application to a feeding trial

HPLC with ion-pairing chromatography and diodearray detection at 355nm was used to determine tetracycline antibiotics in eggs and broiler meat. The analytical methods were optimized and validated. The mean recovery values for oxytetracycline for eggs and for tetracycline for breast meat were 76% . The withinday precision ranged from 8.0 to 11.8% for oxytetracycline in eggs and from 6.1 to 15.5% for tetracycline in breast meat. The between-day precision was 4.8% and 5.0% respectively for oxytetracycline in eggs and tetracycline in breast meat. The limit of detection and the limit of quantitation for oxytetracycline in eggs were 2.2 and 13.0ng/g respectively. These limits for tetracycline in breast meat were 10.5 and 20.9ng/g respectively. Residue values of tetracycline antibiotics in eggs and broiler meat were determined after oral administration of medicated feed. Medicated feed with 840mg/kg oxytetracycline was provided to laying hens for seven successive days. Two days after the administration was stopped, the mean oxytetracycline residue value in the eggs was already lower than the Maximum Residue Limit (MRL)-level and reached 118ng/g. Broilers were supplied with medicated feed containing 480mg/kg tetracycline for seven successive days. Four days after the administration was stopped, the mean tetracycline residue value in breast meat decreased below the MRL and was 86ng/g.     

Residues of sulfadiazine and doxycycline in egg matrices due to cross-contamination in the feed of laying hens and the possible correlation with physicochemical,pharmacokinetic and physiological parameters

In the poultry industry, the widespread use of veterinary drugs such as antimicrobial compounds may lead to the presence of residues in whole eggs, egg white and egg yolk. During this study, laying hens received experimental feed containing sulfadiazine or doxycycline at cross-contamination levels of 2.5%, 5% and 10% of the therapeutic concentration. Since the therapeutic dose is 250?mg?kg^?1 for both substances, cross-contamination concentrations in the feed of 6.25, 12.5 and 25?mg?kg^?1 were expected. Whole egg, egg white and egg yolk samples were collected during the treatment and depletion period and were analysed via liquid chromatography-tandem mass spectrometry. For both drugs, a plateau phase was reached within 3–5 days and residue concentrations were detected in all egg matrices. For the 10% cross-contamination group, residual sulfadiazine concentrations of 208, 299 and 60?µg?kg^?1 and residual doxycycline concentrations of 455, 332, 206?µg?kg^?1 were detected in whole egg, egg white and egg yolk on day 13 of the treatment period, respectively. Both sulfadiazine and doxycycline had higher concentrations in egg white than in egg yolk, but the egg white–egg yolk ratio was higher for sulfadiazine than for doxycycline. As neither drug is allowed in Belgium for use in laying hens, residues may pose food safety concerns.