乳房淋巴结内注射胸腺五肽治疗奶牛隐性乳房炎的研究

将患隐性乳房炎的奶牛30头随机分为5组,3个试验组奶牛分别在乳房淋巴结内注入低、中、高剂量的胸腺五肽（TP-5）;阳性药物对照组奶牛在乳房内灌注＂乳炎＂（主要含林可霉素和新霉素）;空白对照组,不作任何处理。治疗前和治疗后1、2、3周采集奶样进行细菌学检查和体细胞计数（SCC）。停药后4d之内每天采样进行牛奶抗生素残留检测。结果表明,和空白对照组比较,经药物治疗后各组感染乳区有不同程度减少,牛奶SCC减少的幅度依次为阳性药物对照组〉TP-5高剂量组〉TP-5中剂量组〉TP-5低剂量组。＂乳炎＂治疗组在停药后3d之内可以在牛奶中检测到抗生素残留,而TP-5则没有。因此,TP-5对奶牛隐性乳房炎具有治疗作用,并且不会在牛奶中造成有害的残留。     

抗菌药物治疗奶牛子宫内膜炎后牛奶中药物残留及其对酸奶发酵的影响

用TTC法检测44例经过抗菌药物治疗的患子宫内膜炎荷斯坦奶牛。其中，41例采用子宫内灌注药物治疗，主要药物有土霉素、金霉素和庆大霉素；每个病例治疗1～5次不等，3例采用静脉注射，主要药物有磺胺嘧啶钠和头孢噻啶。结果表明，31例经土霉素子宫内灌注的奶牛，停药后第24h所采的奶样均可检出抗生素；其中6头奶牛在第6d仍然抗生素阳性，残留时间最长的可达8d。8例用金霉素子宫灌注治疗的奶牛，停药后第48h所采的奶样，抗生素检出率100％，其在牛奶中的残留时间为2～5d不等。2例经庆大霉素子宫灌注治疗的患病牛，药残时间分别为1～2d。3头经静脉滴注治疗的病牛，牛奶中的药残时间约达到9d以上。此外，从3头用金霉素子宫内灌注的奶牛采集牛奶用于乳酸菌发酵试验。结果表明，牛奶TTC阳性时，发酵产酸较低。在治疗后6h采集的牛奶都不能正常发酵产酸、凝固。3例试验牛牛奶发酵产生的酸度分别于治疗后第13、24和48h恢复到治疗前的水平。     

土霉素在鸡蛋中的残留消除研究

研究临床使用常规剂量及养殖环节加大盐酸土霉素可溶性粉剂量后其在鸡蛋中的残留消除规律。对产蛋期蛋鸡分别给予500 mg/L和667 mg/L 50%盐酸土霉素可溶性粉,集中饮水给药,每日1次,连续5 d。分别采集停药后1～12 d的鸡蛋样品,采用UPLC-MS/MS测定鸡蛋中土霉素的残留量。按上述方法给药后,低、高剂量组分别在停药第1天和停药第2天达到土霉素残留量最高。低、高剂量组的最高残留量分别为142. 72、82. 84μg/kg,均低于国家规定的最高残留限量(200μg/kg),不会造成土霉素残留超标。本试验通过研究土霉素可溶性粉在鸡蛋中的残留情况,确定弃蛋期前后土霉素残留量,以期为蛋鸡产蛋期安全用药,保障食品安全提供科学依据。     

新疆地区绵羊和肉鸡不同组织兽药残留及消除规律研究

为了解新疆地区绵羊生产中使用药物的残留情况,进行了绵羊不同组织兽药残留量的研究。结果表明:停药5d青霉素钠在绵羊肾脏中的残留量最高,是肝脏的4倍,肌肉组织中的残留量最低;停药5d头孢噻呋钠在绵羊各组织内残留量均极低;停药10、20和30d检测结果显示:硫酸链霉素在绵羊的肝脏和肾脏中代谢时间长,残留量高,肌肉组织中代谢快,残留量低;停药17d伊维菌素在绵羊肾脏残留量最高,肝脏和背最长肌均未检出;停药7d阿苯达唑未检出;停药6d左旋咪唑未检出;吡喹酮在停药17、27和37d各检测一批,均未检出。肉鸡42d(出栏)时,新霉素在胸肌和腿肌中残留量最高,肝脏和肾脏中的残留量仅为肌肉组织的四分之一;肉鸡42d(出栏)时,强力霉素在肾脏中的残留量最高,是肌肉组织、心脏和肝脏残留量的10倍左右。证明试验中各种药物的残留量均低于中国和欧共体(EEC)规定的标准残留限量。     

盐酸土霉素可溶性粉在肉鸡组织中的残留消除研究

在常规养殖环境中,对不同日龄肉鸡分别给予250 mg/L和333 mg/L 50%盐酸土霉素可溶性粉,集中饮水给药,每日1次,连续5 d。停药后4 h,1 d,3 d,5 d,6 d,7 d,8 d,9 d,10 d宰杀肉鸡,采集可食性组织(肌肉、肝脏和鸡胗)样品,肌肉、肝脏和鸡胗组织中的残留量采用UPLC-MS/MS测定。结果表明:土霉素主要残留在肝脏组织中;肌肉、肝脏和鸡胗组织的消除速率相似;停药5 d后,两个剂量组的肌肉、肝脏中土霉素残留量均低于最高残留限量(MRL)。休药期计算软件WTl.4结果显示,上述两种方法给药后,建议休药期分别为7、8 d。     

固相萃取-高效液相色谱-二极管阵列检测器测定牛奶中土霉素、金霉素的残留量

土霉素、金霉素均属于四环素类药物，为广谱抗生素，对革兰氏阳性和阴性细菌、立克次氏体等均有抑制作用，在兽医临床上，这两种药物被广泛用于治疗奶牛乳房炎，因此极易残留于牛奶中，牛奶中残留的原型药物能与人体中的钙结合，导致人体钙流失，影响人体健康”。并且由于四环素类药物价格低廉，所以在畜禽饲养中被广泛用作饲料添加剂来预防动物疾病和提高饲料利用率，但食品动物中的药物残留会对消费者的健康造成危害，长期用药会产生耐药菌株。因此许多国家都对这两种药物实施例行监控，我国和欧盟规定牛奶中的四环素类药物总量不得超过100μg／l。笔者采用同相萃取、高效液相色谱法测定土霉素、金霉素残留量。     

牛奶中土霉素残留检测方法改进及临床消除规律探究

试验对牛奶中的土霉素残留检测方法进行了改进,并采用改进后的方法对牛奶中土霉素的临床消除情况进行了探究。样品前处理过程中,选取0.1mol/LNa₂EDTA-Mcllvaine缓冲溶液提取牛奶中的土霉素,正己烷除脂及HLB固相萃取柱净化浓缩。釆用Symmetry Shield RPC18(250mm×4.6mm,5μm)反相色谱柱,以乙腈和0.048%的磷酸溶液(pH2.5)为流动相,采用梯度洗脱的方式对样品进行分析。方法改进后,土霉素的出峰时间为6.5min,峰形尖锐,与样品中的杂质峰分离良好。土霉素标准溶液在5~2000μg/kg范围内线性关系良好,标准曲线R²=0.9999;牛奶中土霉素在10、20、100μg/kg3组浓度的加标回收率分别为87.9%、90.5%和87.8%,批内变异系数范围为2.2%~5.8%,批间变异系数范围为4.0%~5.1%。土霉素在牛奶中的检出限为5μg/kg,定量限为10μg/kg,适用于研究土霉素在牛奶中的残留消除规律。选取了29头产后患有子宫内膜炎的奶牛,分成4个不同剂量组(2、3、4和5g),通过子宫内灌注土霉素的方式进行治疗,然后采用优化后的方法检测牛奶中残留的土霉素。结果发现,4g及以下剂量组给药72h后,牛奶中的土霉素可以消除至残留限量以下;而当给药剂量达到5g时,72h后牛奶中的土霉素未消除至残留限量以下,因此不建议采用5g及以上剂量灌注病牛子宫。     

反相高效液相色谱法测定牛奶中土霉素残留

建立了测定牛奶中土霉素残留的RP-HPLC方法.采用草酸甲醇液提取牛奶中的土霉素,离心,用C18色谱柱(5 μm,250 mm×4.6 mm),甲醇 乙腈 0.01 mol/L草酸溶液(20∶ 12∶ 68)为流动相,流速1 mL/min,检测波长360 nm,以HPLC外标法测定牛奶中土霉素的残留量.结果:土霉素峰面积与浓度呈良好的线性关系,其线性范围为50～1 500 μg/L(r=0.999 9),平均回收率为88%.本法简便、准确、快速,是一种较好的测定牛奶中土霉素残留的方法.     

中药治疗奶牛乳腺炎与"放心奶"

牛奶中抗生素残留问题是世界范围内一直没有办法解决的大问题。欧美各国进行专题研究，已经有２０～３０年，但至今未能找到疗效上可取代抗生素，愈后又无抗生素残留的药物。牛奶中抗生素残留，是对患病奶牛，主要是对乳腺炎等常见疾病治疗时使用抗生素造成的。使用过抗生素后，抗生素就会从奶牛体内移行到乳腺，并持续残留进入牛奶中。由于奶牛群中奶牛乳腺炎的患病率都在４０％左右或更高（美国奶牛患乳腺炎的比例为３８％），由于目前世界各国只能采用抗生素类药物治疗乳腺炎，并且使用抗生素治病期间和治愈后的５～７天内必须将该奶牛四…     

中药治疗奶牛乳房炎及提高生产性能的研究进展

乳房炎是危害奶牛养殖的重要疾病,对奶牛造成巨大的危害和经济损失.奶牛乳房炎的防治主要是应用抗生素疗法.近年来人们对抗生素在牛奶、肉中的残留备受关注.中草药具有低毒性、低残留及安全性好等优势,人们在防治乳房炎中已开始把注意力转向中草药以代替抗生素类药物.本文概述奶牛乳房炎的危害,重点介绍中医药防治奶牛乳房炎的研究进展.以期指导生产实践,科学防治,促进奶牛生产健康持续发展.     

Enzyme-linked immunosorbent assay for screening the plasma residues of tetracycline antibiotics in pigs.

The recommended therapeutic doses of three kinds of tetracyclines, oxytetracycline (OTC, withdrawal period, 10 days), chlortetracycline (CTC, withdrawal period, 5 days) and tetracycline (TC, withdrawal period, 5 days), were each administered to a group of 15 pigs. Blood was sampled before drug administration and during the withdrawal period. The concentration of tetracyclines in plasma, determined by semi-quantitative ELISA, was compared with that of internal standard (10 ppb as oxytetracycline). The absorbance ratio of internal standard to sample (B/Bs) was employed as an index to determine the tissue residues in pigs. All 45 plasma samples from nontreated pigs showed negative in the residue of any of three tetracycline antibiotics. OTC was detected in plasma of pigs treated until the 8th day, CTC until the 4th day, and TC was detected until the 3rd day of its withdrawal period. The present study showed that the semi-quantitative ELISA easily be adopted in predicting tissue residues for tetracycline antibiotics in live pigs.     

Application of a solid-phase fluorescence immunoassay to determine oxytetracycline and tetracycline residues in tissue of olive flounder (Paralichthys olivaceus)

Parallux, a solid-phase fluorescence immunoassay (SPFIA) developed for antibotics residue detection in milk, was applied for analysis of fish tissue. The recommended therapeutic doses of oxytetracycline (OTC, 100 g/ton water, withdrawal period 30 days) and tetracycline (TC, 150 g/ton water, withdrawal period 30 days) were treated to a group of 35 olive flounders (Paralichthys olivaceus) using dipping administration. Muscle was sampled before and after drug treatment 1st, 2nd, 3rd, 5th, 7th, and 14th day. The concentration of oxytetracycline in muscle, determined by SPFIA, was compared with that of internal standard (100 ppb as oxytetracycline). The S/C ratio of sample inhibition value to cutoff inhibition value was employed as an index to determine the muscle residue in olive flounder. To investigate the recovery rate, and standard solutions were added to muscle samples to give final concentrations in muscle of 0.1 and 0.5 microg/ml. The recovery rates of all spiked samples were >89% of the spiked value. OTC and TC were detected in muscle of fishes treated until the 3rd day of withdrawal period. The present study showed that the SPFIA can be easily adopted in predicting tissue residues for OTC and TC in farmed fishes.     

Antibiotic residues (bacterial inhibitory substances) in the milk of cows treated under label and extra-label conditions

The objectives of this study were to describe the depletion pattern of antibiotic residues (microbial inhibitory substances) from the milk of cows treated under field conditions of clinical disease and antibiotic administration, including both label and extra-label use, and to determine if the type of extra-label use, the route of administration, and the drug used were factors associated with prolonged shedding of residues in milk.

Milk samples from 138 cows, treated with a variety of antibiotic products on farms in southwestern Ontario in 1989 and 1990, were collected before treatment and for six days after cessation of treatment. Samples were tested for antibiotic residues with the Brilliant Black reduction test (BR-test) and the Bacillus stearothermophilus var calidolactis disc assay. In 13/138 (9.4%) of cow treatments, at least one milk sample was positive on both antibiotic residue tests after the label milk withholding time for the drug(s) used. In ten of these instances, the antibiotics were administered in extra-label fashion and in three the drugs were reportedly used according to label instructions. Extra-label use of antibiotics was significantly associated with increased risk of antibiotic residues in milk beyond the label withholding time. No significant differences in risk were observed among the various antibiotic products used in the study.

The farms involved in this study were selected on the basis of their proximity to our laboratory; therefore, the frequency of antibiotic residue detection after withholding times may not be indicative of the provincial or national situation. If farmers and veterinarians find themselves in a situation where extra-label use of an antibiotic is necessary, use of an alternative antibiotic that can be used at label dose and with a known withdrawal time may avoid a problem with residues.

     

Microbiological screening test validation for detection of tylosin excretion in milk of cows with low and high somatic cell counts

Antibiotic residues in milk above tolerance levels interfere with dairy product processing and pose potential health risks to consumers. Residue avoidance programmes include, among other components, the observance of withdrawal times indicated in label instructions. Persistence of antibiotics in milk following treatment is influenced by drug, dosage, route of administration, body weight and mammary gland health status. Compositional changes that take place during intramammary infection (IMI) can affect antibiotic excretion in milk, thus modifying milk withdrawal time. The objectives of this study were to validate sensitivity and specificity of a qualitative microbiological method (Charm AIM-96) to detect tylosin in bovine composite milk and to determine the influence of subclinical IMI in tylosin excretion following intramuscular administration. For test validation, two groups of approximately 120 cows were used; one received a single intramuscular injection of tylosin tartrate at a dose of 20 mg/kg, while the other group remained as untreated control. Test sensitivity and specificity were 100% and 94.1% respectively. To determine the influence of subclinical IMI in tylosin excretion, two groups of seven cows, one with somatic cell counts (SCC) < or =250 000 cells/ml and the other with SCC > or =900 000, were administered a single intramuscular injection of tylosin tartrate at a dose of 20 mg/kg. Milk samples were obtained every 12 h for 10 days following treatment. Milk tylosin excretion averaged between 5 and 9 days for cows with low and high SCC respectively (P < 0.0001). Compositional changes in cows with high SCC most likely affect the pharmacokinetic characteristics of tylosin, extending the presence of the antibiotic in milk, thus influencing milk withdrawal times.     

红薯渣对奶牛产奶量和奶品质的影响

摘要试验选用;35头健康无病、处于泌乳中期、胎次相同、体重相近（体重约450kg）、产奶量相近（P〉0．05）的荷斯坦奶牛,随机分为2组：对照组10头,用产奶期正常饲料饲喂;试验组25头,每头牛在对照组日粮基础上投5kg新鲜红薯渣替代5kg苜蓿干草。结果表明：在产奶期日粮中添加新鲜红薯渣对奶牛的产奶量没有显著影响（P〉0．05）;从乳成分试验统计数据看,其对奶牛的乳成分影响不明显,乳脂、乳蛋白、乳糖、乳固形物和非脂固形物均无显著差异（P〉0．05）。     

Effects of subclinical bovine leukemia virus infection on some production parameters in a dairy farm in southern Turkey

Some production parameters of seropositive cows (age, first calving age, 305 day mature equivalent last milk yield production, lifetime mature equivalent milk yield production, lifetime total milk production, lifetime total milking period, lifetime monthly milk production, lifetime daily milk production, lifetime total days of milking, number of inseminations per pregnancy (for last pregnancy), number of calves and calving interval (for last pregnancy)) were analysed in the current study. The study population was clinically healthy Holstein cows from a commercial dairy herd in southern Turkey. Of 109 animals, 65 cows were seropositive by ELISA and the prevalence of bovine leukemia virus (BLV) infection was 59.6%. The prevalence of seropositive cows in 2nd (62.8%), 3rd (64.7%), 4th (61.5%), and 5th (66.6 %) lactations was slightly higher than that of cows in 1st (52.6%) lactations. No statistical differences were observed between BLV seronegative and seropositive cows for production and reproduction parameters analysed in this study (P > 0.05).     

乳房炎牛奶中复方阿莫西林纳米乳的残留检测及消除试验

利用高效液相色谱仪建立复方阿莫西林纳米乳（AMX-LH-NE）在牛奶中的残留监控高效液相色谱法（HPLC）,并通过残留消除试验,研究AMX-LH-NE在乳房炎牛奶中的残留消除规律,确定其弃奶期。结果显示,阿莫西林（AMX）和盐酸左氧氟沙星（LH）分别在7.5～400μg/L和40～600μg/L线性关系良好;平均回收率为（99.72±1.46）%和（99.65±1.53）%;相对标准偏差（relative standard deviation,RSD）为1.46%和1.54%;平均保留时间为（11.59±0.21）min和（6.87±0.02）min;日内精密度RSD为1.59%和1.39%,日间精密度RSD为3.17%和3.29%。在乳房炎牛奶中,AMX和LH的残留量均随着休药时间的延长而迅速降低;AMX的弃奶期为停药后35.96h,LH的弃奶期为停药后32.94h。结果表明,所建立的HPLC方法专属性好,回收率、重复性和精密度高,可为牛奶中AMX-LH-NE的残留监控提供检测方法;利用此检测方法确定的AMX-LH-NE的弃奶期为停药后36h。     

干奶后期饲喂阴离子盐对奶牛离子平衡和产奶的影响

采用28头荷斯坦经产牛按配对试验设计研究了添加阴离子盐对奶牛血液离子浓度、胎衣不下发病率及产后6个月泌乳性能的影响。结果表明,饲喂阴离子盐饲粮5天使尿液pH值显著降低(P<0.01),产前血清氯离子浓度提高(P<0.05),钙离子浓度趋于上升,并使分娩后胎衣不下的发病率降低31.2个百分点P=0.05)。第1、2、3、4泌乳月校正乳产量提高,且趋向提高乳脂率,但对乳蛋白、乳糖、非脂乳固体含量等乳成分没有明显影响(P<0.2)。饲喂阴离子盐能够显著降低产奶牛第2、3、4个泌乳月乳中的体细胞数P=0.03(0.09)。本试验结论:产前饲粮中添加阴离子盐能够改善奶牛产后的健康状况,提高泌乳性能。