超高效液相色谱-串联质谱法快速测定禽蛋中氯霉素、氟苯尼考及其代谢物残留

建立了快速测定禽蛋中氯霉素、氟苯尼考及氟苯尼考胺的超高效液相色谱-串联质谱分析方法。禽蛋用乙腈提取后，再用正己烷液液分配除脂，浓缩后用超高效液相色谱分离，以乙腈和10%甲醇水为流动相进行梯度洗脱，MRM反应监测模式检测。结果表明在5-200μg/L的系列浓度范围内均呈良好线性关系，相关系数均大于0.999。氯霉素、氟苯尼考、氟苯尼考胺的检测限为0.5μg/kg，定量限为2.0 μg/kg，本方法在2μg/kg～20μg/kg添加浓度范围内平均回收率为60%～100%，精密度小于20%。该方法方便快捷、定性准确适于禽蛋中的氯霉素、氟苯尼考及氟苯尼考胺药物残留检测。     

鳗鱼中氯霉素残留的UPLC-MS/MS检测方法研究

建立了快速测定鳗鱼中氯霉素药物残留的超高效液相色谱串联三重四极杆质谱(UPLC-MS/MS)分析方法。样品添加同位素内标后,经1%HCl水解,乙酸乙脂提取、净化、流动相溶解,通过Waters ACQUITYUPLCTMBEHC18色谱柱分离,以串联质谱在多反应监测(MRM)模式下测定,在2 min内完成氯霉素的定量分析。结果表明:氯霉素在0.02~1.0μg/kg浓度范围内线性良好,相关系数(r)为0.996 5;在0.05、0.1、0.5μg/kg添加水平条件下,氯霉素加标回收率为86.6%~92.5%,相对标准偏差(RSD)均小于7%(n=5);本方法对氯霉素检出限和定量限分别为0.003μg/kg和0.011μg/kg。     

猪肉及组织中β-受体激动剂UPLC-MS/M检测方法研究

超高效液相色谱串联质谱法(UPLC-MS/MS)检测猪肉中克伦特罗、莱克多巴胺、沙丁胺醇3种β-受体激动剂残留方法.选用盐酸葡萄糖醛苷酶/芳基硫酸酯酶水解,混合型阳离子交换固相萃取净化,以0.1%甲酸水溶液-0.1%甲酸乙腈溶液-甲醇为流动相,超高效液相色谱串联质谱法检测,在1.0、5.0、10μg/kg浓度添加水平,空白肌肉组织中3种药物添加平均回收率范围84~95%,标准偏差3.6~8.1%.该方法检测限为0.1μg/kg,定量限为0.3μg/kg,具有准确敏感特性.     

超高效液相色谱-串联质谱法测定猪牛组织中甲基盐霉素残留量

建立超高效液相色谱-串联质谱法测定猪牛组织中甲基盐霉素残留量。猪、牛组织中残留的甲基盐霉素,经乙腈溶液提取,硅胶固相萃取柱净化,超高效液相色谱-串联质谱法测定,外标法定量。甲基盐霉素在5 ng/mL～250 ng/mL的浓度范围内呈现良好的线性关系,甲基盐霉素在猪、牛肌肉、肝脏、肾脏、脂肪中的检测限均为2.5μg/kg,定量限均为5.0μg/kg,猪牛肌肉、肝脏、肾脏、脂肪中5.0 ng/g～100 ng/g添加浓度范围内的回收率均值为71.9%～88.4%,批内批间RSD值均<15%。     

同位素稀释-液相色谱串联质谱法测定渔用饲料中氟苯尼考及氟苯尼考胺残留

文章旨在建立同时测定渔用饲料中氟苯尼考及氟苯尼考胺残留量的同位素稀释-高效液相色谱串联质谱法。以氯霉素-D5和氟苯尼考胺-D3位内标，样品用氨化乙酸乙酯提取，混合型阳离子交换固相萃取柱（MCX）净化，在金刚烷基色谱柱上分离，采用LC-MS/MS选择多反应监测（MRM）模式进行定性、定量分析。结果表明：氟苯尼考及氟苯尼考胺的检出限（LOD）为0.2和0.5μg/kg，定量限（LOQ）为1.0和2.0μg/kg，检测结果的相对标准偏差为2.04%～12.1%（n=6），加标回收率达到64.3%～97.0%。该方法具有比较高的重现性和选择性，在渔用饲料中氟苯尼考及氟苯尼考胺的残留测定中具有很好的应用前景。 [关键词]高效液相色谱-串联质谱法|同位素稀释法|氟苯尼考|氟苯尼考胺|渔用饲料     

超高效液相色谱-串联质谱法测定鸡蛋中沙拉沙星残留的研究

建立了鸡蛋中沙拉沙星残留检测的液相色谱-串联质谱法。样品经1 mol/L磷酸和乙腈提取后,饱和正己烷除脂净化,以0.1%甲酸溶液和乙腈为流动相,液相色谱-串联质谱法测定,内标法定量。试验结果表明：沙拉沙星在1～25 ng/mL浓度范围内线性关系良好,相关系数r大于0.999。沙拉沙星在鸡全蛋及其蛋清、蛋黄中的检测限均为0.5μg/kg,定量限为1μg/kg。沙拉沙星在1、10、20μg/kg浓度添加水平内的平均回收率范围为97.0%～105.4%,批内、批间相对标准偏差在1.3%～10.3%范围之间。本方法适用于鸡全蛋及其蛋清、蛋黄中沙拉沙星残留量的测定。     

超高效液相色谱-串联质谱法测定牛乳、发酵乳和乳粉中四环素类药物残留

建立超高效液相色谱-串联质谱法同时检测牛乳、发酵乳和乳粉3种基质中4种四环素类药物残留的检测方法。对前处理方法和仪器上机条件进行研究。以EDTA-Mcllvaine缓冲液进行提取,经HLB固相萃取柱净化,甲醇-乙酸乙酯(1∶9,V/V)洗脱,氮吹后复溶,采用电喷雾离子源正离子模式、多反应监测模式进行检测。结果表明:乳粉中四环素、土霉素、金霉素和强力霉素的定量限均为10μg/kg;液态乳和发酵乳中4种药物的定量限均为2μg/kg;四环素类药物添加量为2～100μg/kg时,回收率为63.1%～100.6%,相对标准偏差为1.8%～10.7%,基质效应为100.5%～122.1%。该方法准确、快速、灵敏度高、重复性好、线性范围宽,适用于液态乳、发酵乳和乳粉中4种四环素类药物残留的测定。     

高效液相色谱-串联质谱法快速测定乳与乳粉中20种同化激素

建立了液相色谱-电喷雾串联质谱同时测定乳与乳粉中11种甾类和9种β-受体激动剂类同化激素的快速确证方法。样品经体积分数0.1%甲酸乙腈溶液提取,正己烷脱脂,HLB固相萃取柱净化后,以0.1%甲酸甲醇-0.1%甲酸水为流动相梯度洗脱,通过C8色谱柱分离,电喷雾正离子多反应监测模式检测。在优化条件下,20种目标物在0.05~50μg/L范围内线性良好,相关系数均大于0.996;方法定量限(RSN=10)在0.1~1.0μg/kg之间;不同添加水平回收率为52.8%~97.4%,相对标准偏差(n=6)为2.8%~9.6%。多种市售纯牛奶和乳粉的测定结果表明,该方法操作简单、测定结果准确,可用于乳与乳粉中甾类和β-受体激动剂类激素多残留的快速测定。     

反相高效液相色谱测定家兔肌肉中氯霉素残留量的研究

建立了反相高效液相色谱分析法测定家兔肌肉中氯霉素残留量的实验方法,能快速、简便、灵敏地测定兔肉中的氯霉素残留。本方法最低检出浓度为10μg.kg-1,氯霉素浓度在0.01～10μg.ml-1范围内具有良好的线性关系,平均回收率为92.6%,RSD为1.85%～2.78%。本方法适于动物肌肉组织中氯霉素残留的监测。     

鸡皮脂组织中尼卡巴嗪残留量的测定高效液相色谱-串联质谱法

本研究旨在建立一种检测鸡皮脂组织中尼卡巴嗪标志物4,4-二硝基均二苯脲残留量的高效液相色谱-串联质谱法。组织样品用乙腈提取,氮气吹干浓缩,正己烷除脂、甲醇水溶液(75∶25,v/v)萃取,高效液相色谱-串联质谱法测定,内标法定量。该方法在50~1000 ng/m L范围内,线性关系良好,线性相关系数r=0.9998,该方法的检测限和定量限分别为2.5μg/kg和25μg/kg,加标平均回收率为98.10%~114.11%,批内批间的RSDs均小于5%,具有较好的回收率和重复性。该方法简单、快速、有效,可用于鸡皮脂中尼卡巴嗪残留标志物残留量的定量检测。     

Feline intracranial neoplasia: retrospective review of 160 cases (1985-2001)

The purpose of this study was to determine the frequency of different tumor types within a large cohort of cats with intracranial neoplasia and to attempt to correlate signalment, tumor size and location, and survival time for each tumor. Medical records of 160 cats with confirmed intracranial neoplasia evaluated between 1985 and 2001 were reviewed. Parameters evaluated included age, sex, breed, FeLV/FIV status, clinical signs, duration of signs, number of tumors, tumor location(s), imaging results, treatment, survival times, and histopathologic diagnosis. Most of the cats were older (11.3 +/- 3.8 years). Primary tumors accounted for 70.6% of cases. Metastasis and direct extension of secondary tumors accounted for only 5.6 and 3.8% of cases, respectively. Twelve cats (7.5%) had 2 or more discrete tumors of the same type, whereas 16 cats (10.0%) had 2 different types of intracranial tumors. The most common tumor types were meningioma (n = 93, 58.1%), lymphoma (n = 23, 14.4%), pituitary tumors (n = 14, 8.8%), and gliomas (n = 12, 7.5%). The most common neurological signs were altered consciousness (n = 42, 26.2%), circling (n = 36, 22.5%), and seizures (n = 36, 22.5%). Cats without specific neurological signs were common (n = 34, 21.2%). The tumor was considered an incidental finding in 30 (18.8%) cats. In addition to expected relationships (eg, meninges and meningioma, pituitary and pituitary tumors), we found that lesion location was predictive of tumor type with diffuse cerebral or brainstem involvement predictive of lymphoma and third ventricle involvement predictive of meningioma.     

The Prevalence and Intensity of Helminth and Coccidial Infections in Dairy Cattle in Central Kenya

A survey of gastrointestinal parasite infections of young (<6 months old), immature (6–12 months old) and adult (>12 months old) dairy cattle on 16 farms in Kiambu District, Kenya was conducted during a dry season (September 1991 to January 1992) and during a wet season (March to July 1992). The survey was based on monthly coproparasitological examination of cohorts and worm counts in tracer calves. The effects of age, sex, farm and season on the prevalence and intensity of helminth and coccidial infections were determined. Faecal egg and oocyst counts revealed that the overall prevalences were: strongyles (including trichostrongyles) (85.5%), liver flukes (Fasciola gigantica) (34.0%), coccidia (30.9%) and tapeworms (9.6%). Eight species of the protozoan Eimeria were identified, the most prevalent species being E. bovis and E. zuernii. The most prevalent nematode genera were Haemonchus, Cooperia, Oesophagostomum and Trichostrongylus. Season, farm and age of the animals had a significant (p<0.05) influence on the intensity of infection with strongyles, liver flukes and coccidia, whereas the sex of the animals had no significant (p>0.05) effect on the prevalence or intensity of infections. A higher intensity of infection with strongyles and coccidia was found in the wet season than in the dry season (p<0.05). The age-specific intensity was in the following order: for strongyles, immature animals of 6–12 months of age had the highest egg counts, followed by young calves and adults. Calves had significantly (p<0.05) higher oocyst counts than immatures or adults. Liver fluke egg counts did not differ significant (p>0.05) between immatures and adult cattle.     

Hypothalamic dopamine is required for salsolinol‐induced prolactin secretion in goats

The aim of the present study was to clarify the relationship between hypothalamic dopamine (DA) and salsolinol (SAL) for the secretion of prolactin (PRL) in goats. SAL or thyrotropin‐releasing hormone (TRH) was intravenously injected into female goats treated with or without the D₂ DA receptor antagonist haloperidol (Hal), which crosses the blood‐brain barrier, and the PRL‐releasing response to SAL was compared with that to TRH. PRL‐releasing responses to SAL, Hal, and Hal plus SAL were also examined after a pretreatment to augment central DA using carbidopa (Carbi) and L‐dopa. The PRL‐releasing response to Hal alone was greater than that to SAL or TRH alone. The PRL‐releasing response to Hal plus SAL was similar to that of Hal alone. In contrast, the PRL‐releasing response to Hal plus TRH was greater than that to TRH or Hal alone. The treatment with Carbi plus L‐dopa inhibited SAL‐ and Hal‐induced PRL secretion. The inhibition of the PRL‐releasing response to SAL disappeared when SAL was injected with Hal. These results indicate that the mechanisms underlying the SAL‐induced PRL response differ from those of TRH, and suggest that hypothalamic DA and its synthesis is associated in part with SAL‐induced PRL secretion in goats.     

Prevalence of gastric lesions in racing Alaskan sled dogs

Human and equine athletes are reported to have a high prevalence of gastric disease, and anecdotal evidence suggests a similar phenomenon applies to racing sled dogs. To investigate the prevalence of gastric disease in racing sled dogs, we conducted 2 gastroscopy studies on dogs competing in the annual Iditarod Sled Dog Race. A pilot study of dogs that were either dropped from the 2000 Iditarod Sled Dog Race because of illness or that finished the race indicated that, approximately 5 days after competing, 10 of 28 dogs (35%) had endoscopic evidence of gastric ulceration, erosion, or hemorrhage. The next year, an endoscopic study of 73 dogs participating in the 2001 Iditarod race was performed in order to evaluate a larger population of dogs. Data from 70 of these dogs could be used; 34 (48.5%) had ulceration, erosion, gastric hemorrhage, or some combination of these findings. When this group of 70 dogs was compared retrospectively to a control group of 87 dogs presented to the Texas A&M University (TAMU) Veterinary Medical Teaching Hospital, the Iditarod sled dogs had a significantly higher prevalence (P = .049) of gastric lesions. These findings suggest that, similar to athletes of other species, elite canine athletes have an increased prevalence of gastric disease compared to the canine population at large.     

Laboratory diagnosis of respiratory diseases of cattle

The authors describe the procedure of laboratory diagnosis for bovine respiratory diseases: direct diagnosis by isolation and for identification of bacteria or viruses and indirect diagnosis by serological methods. They specify the restraints and limits of this diagnosis and the significance results which are obtained and connected with knowledge of anamnestic information.     

The effect of peri-parturient anthelmintic treatment on the productivity of dairy cattle in subtropical western India

Trials with fenbendazole (Panacur, Hoechst India Ltd) were carried out on two commercial farms in subtropical western India to study the response and economics of nematode treatment in adult dairy cows. Milk yield, lactation length, time to first oestrus and worm egg output were monitored in treated and control groups. Treatment reduced the egg count considerably. Treated cows produced 142 litres more milk over 100 days (p<0.05), with extension of lactation length and advancement of time to first oestrus. The economic gain in terms of milk yield far outweighed the cost of anthelmintic used.     

An Evaluation of the Acceptability as Forage of Some Nutritive and Antinutritive Components and of the Dry Matter Degradation Profiles of Five Species of Ficus

The suitability of five species of Ficus, F. mucoso, F. thonningii, F. polita, F. religiosa and F. benjamina, for feeding ruminant livestock was studied. The nutritive and antinutritive components were determined and the acceptability of the forages to livestock was assessed using a cafeteria method in 8 adult small ruminants. Also, the degradation potential of the dry matter of the five Ficus species was investigated using 3 fistulated sheep. The crude protein (CP) content of the Ficus species varied significantly (p < 0.05), ranging from 130 to 180 g/kg DM. The content of neutral detergent fibre (NDF) also varied significantly (p < 0.05), ranging from 650 to 710 g/kg DM. The organic matter (OM) contents did not differ significantly (p > 0.05), having a mean value of 916 g/kg DM. The concentrations of tannin, saponin, phytic acid and oxalic acid were low. The acceptability of the forage was similar for four of the species but poor for F. polita. The extent of DM degradation varied significant among the Ficus species, the ranking order being F. benjamina > F. thonningii > F. mucoso > F. religiosa > F. polita.