UPLC-MS/MS法检测动物性食品中肝脏、肾脏组织中氯霉素残留量

建立了动物性食品中肝脏、肾脏组织氯霉素残留检测的超高效液相色谱-串联质谱（UPLC-MS／MS）分析方法。样品用β-葡萄糖醛酸苷酶酶解后乙酸乙酯提取,C18（500mg／3cc）固相萃取柱净化,液相色谱-串联质谱负离子模式测定,内标法定量。结果表明：氯霉素在0．5～10．0ng／mL的系列浓度范围内均呈良好线性关系,相关系数r均大于0．990。样品中氯霉素的检测限为0．1μg／kg,定量限为0．2μg/kg。本方法氯霉素在0．2、0．4、2μg／kg的添加浓度范围内,平均回收率均为70％～120％,相对标准偏差（RSD）均小于20％。该方法具有操作简便快捷、结果灵敏度高、准确度高等优点。     

动物源食品中氯霉素、甲砜霉素、氟苯尼考及氟苯尼考胺残留检测－超高效液相色谱-串联质谱法研究

建立了动物源食品中氯霉素、甲砜霉素、氟苯尼考及氟苯尼考胺残留检测的超高效液相色谱-串联质谱（UPLC—MS／MS）分析方法。样品在碱性条件下用乙酸乙酯提取后,再用正己烷去除脂肪,浓缩后用BEH C18（50mm×2．1mm,1．7μm）色谱柱分离,以乙腈和水为流动相进行梯度洗脱,流速为0．3mL／min,多反应监测（MRM）模式检测。结果表明：四种药物在2—500μg／L的系列浓度范围内均呈良好线性关系,相关系数r均大于0．990。样品中氯霉素的检测限为0．1μg／kg,定量限为0．2μg/kg;甲砜霉素、氟苯尼考和氟苯尼考胺的检测限为0．5μg/kg,定量限为1μg／kg。本方法氯霉素在0．2～1μg／kg的添加浓度范围内,甲砜霉素、氟苯尼考及氟苯尼考胺在1—50μg／kg的添加浓度范围内平均回收率均为70％-120％,相对标准偏差（RSD）均小于20％。该方法具有简便快捷、灵敏度高、定性准确等特点。     

鸡组织中氯霉素残留的气相色谱-微电子捕获检测方法研究

建立了鸡肌肉和鸡肝脏组织中氯霉素残留的气相色谱-微电子捕获检测方法。用乙酸乙酯提取样品中的药物，正己烷脱脂，乙酸乙酯液-液分配，氮气吹干后，用Sylon BFT衍生化，进配有微电子捕获检测器（μECD）的气相色谱仪测定，外标法定量。鸡肌肉组织在0．1、0．5、1．0μg／kg三个添加水平，平均回收率为90．2％～94．3％，日内变异系数在4．5％-11．6％之间，日间变异系数在7．8％～14．3％之间，检测限0．05μg/kg，定量限0．10μg/kg。鸡肝脏组织在0．2、0．5、1．0μg/kg三个添加水平，平均回收率为82．9％～90．8％，日内变异系数在7．0％～11．2％之间。日间变异系数在7．9％～14．5％之间，检测限0．10μg/kg，定量限0．20μg/kg。     

动物性食品中己烯雌酚残留量检测方法评定

用于检测动物性食品中己烯雌酚残留量的常用方法有放射免疫测定(RIA)、酶免疫测定(EIA)、气相色谱(GC)、高效液相色谱(HPLC)和薄层色谱(TLC)。比较这几种方法，认为RIA法测定的灵敏度较高，测定肝脏中DES的最低检出限可达0．3μg／kg，但对放射防护的要求较高，只能在专门实验室进行。GC法需增加衍生化步骤，检出限为2～10μg／kg。HPLC法用电化学检测器的最低检出限是0．1～0．2μg／kg。TLC法用硅胶作铺板，其最低检出限是0．1μg／kg。EIA法灵敏度高、特异性强，测定中华鳖肌肉中DES的最低检出限0．02μg／kg，是目前用于检测大量样品的首选方法。     

林可霉素在饲料中残留的微生物学检测方法

建立了林可霉素在配合饲料中残留的微生物学检测方法。样品用二氯甲烷提取经浓缩、溶剂转换．制成试样溶液，再用藤黄微球菌作为检定茼进行含量测定。结果显示。林可霉素在0．15-2．4μg／ml的浓度范围内具有良好线性关系（r=0．9991）。配合饲料中3种添加浓度1．00μg／g、400μg／g、8．00μg／g的平均回收率为80．2％（n=9）。RSD分别为5．7％、4．2％、2．2％（n=3）。     

气相色谱-质谱法测定鸡肉组织中氯霉素残留的研究

气相色谱-质谱法（GC-Ms）检测鸡肉组织中氯霉素的残留量。用乙酸乙酯提取鸡肉组织中的氯霉素，用正己烷净化，BSTFA＋TMCS衍生。采用负化学电离源（CI）方式进行选择离子扫描（SIM），选择离子包括376，378，466，468，470。方法的检测限为0．1μg／kg（S／N》10），线性范围为0．5-50μg／kg，加标回收率为70．0％-94．0％，相对标准偏差（n=5）为8．58-12．50％。该法具有灵敏度高，实用性强和操作简单等优点。     

氟苯尼考与氯霉素对鸡大肠杆菌病的疗效比较

以试管肉汤2倍稀释法测定氟苯尼考及氯霉素对鸡大肠埃希氏菌的最小抑菌浓度（MIC），然后对实验性鸡大肠杆菌病病鸡进行治疗试验，内服3d,2次／d。结果表明，氟苯尼考及氯霉素对鸡大肠埃希氏菌的最小抑菌浓度分别是3.2μg/mL和1.6μg/mL；以氟苯尼考40mg/kg和氯霉素40mg/kg体重给鸡（每组40只）内服后，对大肠杆菌病的治愈率分别为77．5％和55．0％,而感染对照组的死亡率为95．0％。     

超高效液相色谱-串联质谱法测定猪肉中巴喹普林残留

建立了猪肉中巴喹普林药物残留的超高效液相色谱一串联质谱测定方法,样品用乙酸乙酯提取,吹干后用60％乙腈水（0．1％甲酸）溶解,供液相色谱一串联质谱法分析,内标法定量。结果表明：巴喹普林标准溶液在100～800μg／L范围内呈现良好线性,r2均大于0．998;方法检出限为5μg／kg,定量限为10μg／kg;巴喹普林在10～80μg／kg添加范围内的平均回收率为90．8％-108％,批内、批间RSD均小于6．9％。该方法简便快捷、灵敏度高、定性准确,能满足食品安全检测右吴浩妾田．的霉求．     

鸡蛋中四环素类药物残留量测定的高效液相色谱法研究

建立了鸡蛋中土霉素、四环素、金霉素、多西环素残留量测定的高效液相色谱法。样品经弱酸性缓冲液提取后,HLB固相萃取柱净化后,反相液相色谱分离测定,本方法的检出限为10μg／kg,定量限为50μg／kg。四种四环素类药物在50～1000ng／mL范围内呈线性相关。在100～400ng／g添加浓度范围内,平均回收率为60％～110％,批内变异系数在3．2％～13．7％之间（n=5）,批间变异系数在0．9％-5．3％之间（n=4）。结果表明,该法简单、灵敏、特异性强,适用于鸡蛋中土霉素、四环素、金霉素、多西环素残留量的测定。     

快速测定婴幼儿乳粉中的氯霉素残留

建立一种高效液相色谱一串联质谱法快速测定婴幼儿乳粉中氯霉素残留的方法。样品以D5-氯霉素为内标,碱化后,经乙酸乙酯提取、低温离心、氮吹浓缩,流动相复溶,采用高效液相色谱一串联质谱法测定。结果表明：在0．1-5μg/L范围内氯霉素呈良好的线性关系,高、中、低浓度回收率为80％～110％,精密度小于15％,定量限为0．1μg/kg。本方法快速、简便,适于乳粉中氯霉素残留的快速测定。     

Phase I evaluation of CCNU (lomustine) in tumor-bearing cats

1-(2-Chloroethyl)3-cyclohexyl-1-nitrosourea (CCNU) is an alkylating agent in the nitrosourea subclass. A prospective evaluation of CCNU was done to determine the maximally tolerated dosage of CCNU in tumor-bearing cats. Response data were obtained when available. Twenty-five cats were treated with CCNU at a dosage of 50-60 mg/m3 body surface area. Complete hematologic data were available for 13 cats. Neutropenia was the acute dose-limiting toxicity. The median neutrophil count at the nadir was 1,000 cells/microL (mean, 2,433 cells/microL; range, 0-9,694 cells/microL). The time of neutrophil nadir was variable, occurring 7-28 days after treatment, and counts sometimes did not return to normal for up to 14 days after the nadir. Based on these findings, a 6-week dosing interval and weekly hematologic monitoring after the 1st treatment with CCNU are recommended. The nadir of the platelet count may occur 14-21 days after treatment. The median platelet count at the nadir was 43,500 cells/microL. No gastrointestinal, renal, or hepatic toxicities were observed after a single CCNU treatment, and additional studies to evaluate the potential for cumulative toxicity should be performed. Five cats with lymphoma and 1 cat with mast cell tumor had measurable responses to CCNU. Phase II studies to evaluate antitumor activity should be completed with a dosing regimen of 50-60 mg/m3 every 6 weeks.     

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.     

Furosemide continuous rate infusion in the horse: evaluation of enhanced efficacy and reduced side effects

Continuous rate infusion (CRI) of furosemide in humans is considered superior to intermittent administration (IA). This study examined whether furosemide CRI, compared with IA, would increase diuretic efficacy with decreased fluid and electrolyte fluctuations and activation of the renin-angiotensin-aldosterone system (RAAS) in the horse. Five mares were used in a crossover-design study. During a 24-hour period, each horse received a total of 3 mg/kg furosemide by either CRI (0.12 mg/kg/h preceded by a loading dose of 0.12 mg/kg IV) or IA (1 mg/kg IV q8h). There was not a statistically significant difference in urine volume over 24 hours between methods; however, urine volume was significantly greater after CRI compared with IA during the first 8 hours ([median 25th percentile, 75th percentile]: 9.6 L [8.9, 14.4] for CRI versus 5.9 L [5.3, 6.0] for IA). CRI produced a more uniform urine flow, decreased fluctuations in plasma volume, and suppressed renal concentrating ability throughout the infusion period. Potassium, Ca, and Cl excretion was greater during CRI than IA (1,133 mmol [1.110, 1,229] versus 764 mmol [709, 904], 102.7 mmol [96.0, 117.2] versus 73.3 mmol [65.0, 73.5], and 1,776 mmol [1,657, 2.378] versus 1,596 mmol [1,457, 1,767], respectively). Elimination half-lives of furosemide were 1.35 and 0.47 hours for CRI and IA, respectively. The area under the excretion rate curve was 1,285.7 and 184.2 mL x mg/mL for CRI and IA, respectively. Furosemide CRI (0.12 mg/kg/h) for 8 hours, preceded by a loading dose (0.12 mg/kg), is recommended when profound diuresis is needed acutely in horses.     

The Epidemiology of Gastrointestinal Nematodes of Dairy Cattle in Central Kenya

The epidemiology of H. placei and of other gastrointestinal nematodes in yearling dairy cattle was examined on two farms in Kiambu District, central Kenya during each of 13 one-month periods from April 1993 to April 1994. On each farm, 32 newly weaned dairy calves were given a single dose of albendazole and then placed on experimental pastures. Twelve of the animals were designated for bi-monthly slaughter (n = 2) and analysis of worm population characteristics and 20 were designated for blood and faecal collection and for weighing. Two parasite-free tracer calves were grazed alongside the weaner calves each month throughout the study period and were also slaughtered for analysis of worm populations. Faecal egg counts, haematological and serum pepsinogen determinations, herbage larval counts, and animal live weight changes were recorded monthly. The study revealed that Haemonchus placei, Trichostrongylus axei, Cooperia spp. and Oesophagostomum radiatum were responsible for parasitic gastroenteritis and that H. placei was the predominant nematode present in the young cattle on both farms. Faecal egg counts from resident cattle and necropsy worm counts revealed that pasture larval levels were directly related to the amount of rainfall. The total worm burdens in the animals were highest during the rainy season (March–June and October–December) and lowest during the dry seasons (July–September and January–February). The very low recovery of immature larvae of H. placei from the tracer calves indicated that arrested development is not a feature of the life cycle of this parasite in central Kenya. The maintenance of the parasite population depended on continuous cycling of infection between the host and the pasture. The agroclimatic conditions of the study area were such that, in general, favourable weather conditions for the development and survival of the free-living stages of gastrointestinal nematodes existed all year round.     

Diversity of Ectoparasites in Sheep Flocks in Sa~o Paulo,Brazil

The occurrence of ectoparasites in sheep flocks is frequently reported but seldom quantified. Sheep production used to be a predominantly family activity in the state of Sa~o Paulo (Brazil), but it began to become a commercial activity in the past decade. Thus, information about the ectoparasites existing in sheep flocks has become necessary. The present data were obtained by means of questionnaires sent to all sheep breeders belonging to the `Associaça~o Paulista de Criadores de Ovinos' (ASPACO; Sa~o Paulo State Association of Sheep Breeders). Response reliability was tested by means of random visits paid to 10.6% of the respondents. Most of the properties (89.5%) reported the presence of one or more ectoparasites. Screw-worm (Cochliomyia hominivorax) was the most frequent ectoparasite (72.5%), followed by bot fly larvae (Dermatobia hominis, 45.0%), ticks (Amblyomma cajennense) and Boophilus microplus, 31.3%) and finally lice (Damalinia ovis, 13.8%). Combined infestations also occurred, the most common one being screw-worm with bot fly larvae (36.0%) followed by bot fly larvae with ticks (13.9%), screw-worm with ticks (9.3%), bot fly larvae with lice (6.9%), and ticks with lice (5.0%). The most common triple combination was screw-worm, bot fly larvae and ticks (12.8%). Breeds raised for meat or wool were attacked by bot fly larvae and ticks more often than other breeds. Lice were only absent from animals of indigenous breeds. The relationships among these ectoparasites are discussed in terms of sheep breeds, flock size, seasonality and the ectoparasitic combinations on the host.     

Evaluation of biohydrogenation rate of canola vs. soya bean seeds as unsaturated fatty acids sources for ruminants in situ

An experiment was conducted to study disappearance of C14 to C18 fatty acids, lag times and biohydrogenation (BH) rates of C18 fatty acids of ground soya bean and canola seeds in situ. Three ruminally fistulated Dallagh sheep were used to determine ruminal BH of unsaturated fatty acids (UFAs). Differences in the disappearance of fatty acids through the bags and lag times were observed between the oilseeds. We saw that the longer the incubation time of the oilseeds in the rumen, the lower the content of C18:2 and C18:3. Significantly higher lag times for both C18:2 and C18:3 were observed in ground canola compared to ground soya bean. BH rates of C18:2 and C18:3 fatty acids in soya bean were three times higher than those of canola. These results suggest that the fatty acid profile of fat source can affect the BH of UFAs by rumen micro‐organisms. So that UFAs of canola had higher ability to escape from ruminal BH. It seems that fatty acid profile of ruminant products is more affected by canola seed compared to soya bean seed.     

Serum biochemical values and mineral element contents of tissues in yaks

Serum biochemical values and the wet weight to dry weight ratios of tissues were determined in yaks in Shandan county of Gansu province. The liver, kidney, heart and muscle contents of seven elements in yaks were also analysed. Most serum biochemical values were similar to those of cattle, camels and sheep, but the calcium concentration was considerably above the normal range for other ruminants. The liver contained the highest concentrations of copper, manganese and cobalt and the kidney of selenium, iron and calcium.Abbreviations Alb albumin - ALT alanine aminotransferase - AST aspartate aminotransferase - BUN blood urea nitrogen - Chol cholesterol - Glob globulin - -GT -glutamyl transpeptidase - IP inorganic phosphorus - TP total protein     

Avian brood parasitism — a growing research area in behavioral ecology (part Ⅱ)

正We are pleased to publish the second special issue on avian brood parasitism and to be responsible guest editors for the two special issues of Chinese Birds (Vol. 3, No. 4, 2012 and Vol. 4, No. 1, 2013), entitled "Avian Brood Parasitism - A Growing Research Area in Behavioral Ecology". The first issue was published in December 2012. The goal of the two special issues is to publish accumulated knowledge and some of the recent developments in     

Internal Parasites and Haematological Values in Cattle Slaughtered in Buea Subdivision of Cameroon

Tropical Animal Health and Production -