癸氧喹酯抗柔嫩艾美耳球虫洛阳分离株的效果试验

以抗球虫指数(Anticoccidial Index,ACI)、料肉比及增重为指标,研究了癸氧喹酯抗鸡柔嫩艾美耳球虫洛阳分离株的效果.结果表明,根据54.4 mg/kg、27.2 mg/kg、13.6 mg/kg体重的剂量按饲料比拌料给药,抗球虫指数(ACI)分别达到183.57、145.53和127.80,与感染不给药组相比,料肉比分别降低30.04％、10.60％和3.18％,高剂量组增重与不感染对照组没有显著差异.癸氧喹酯以54.4 mg/kg体重的浓度拌料可以预防洛阳地区鸡球虫病感染,试验结果为临床上有效利用癸氧喹酯控制鸡球虫病提供了重要依据.     

癸氧喹酯溶液预防人工感染肉仔鸡球虫病的药效试验

研究了癸氧喹酯溶液对肉鸡球虫病的预防效果。结果表明,癸氧喹酯溶液按15mg/kg饮水,抗球虫指数为190．属高效抗球虫药物。     

柔嫩艾美耳球虫2个抗药株的抗药性评估

为检测实验室长期保存的柔嫩艾美耳球虫马杜拉霉素抗药株和地克珠利抗药株的遗传稳定性,采用鸡体试验法,以抗球虫指数、最适抗球虫活性百分率、病变记分减少率和相对卵囊产量4项指标,评价2个抗药株对地克珠利、癸氧喹酯、马杜拉霉素等3种抗球虫药物的抗药性,并以柔嫩艾美耳球虫敏感株为对照。结果显示,柔嫩艾美耳球虫敏感株对3种抗球虫药物均无抗药性,4项指标全部阴性。柔嫩艾美耳球虫马杜拉霉素抗药株对马杜拉霉素为完全耐药,4项指标全部阳性;对地克珠利、癸氧喹酯则表现为无抗药性,4项指标全部阴性。柔嫩艾美耳球虫地克珠利抗药株对地克珠利表现为完全耐药,4项指标全部阳性;对马杜拉霉素表现为中度耐药,2项指标阳性;对癸氧喹酯则表现为无抗药性,4项指标全部阴性。结果表明,在实验室已繁殖保存10余年的柔嫩艾美耳球虫2个抗药虫株对其诱导药物具有明显抗药性,实验室保种繁殖方法可行,虫株遗传稳定性良好,为利用该虫株进行球虫抗药性机制等相关研究奠定了基础。     

柔嫩艾美球虫常州株对5种抗球虫药的抗药性分析

将柔嫩艾美耳球虫(E.tenella)常州分离株感染14日龄苏禽黄羽肉鸡,设立5个用药组、1个感染不用药对照组和1个不感染不用药对照组,以相对卵囊产量、病变记分减少率、最适抗球虫百分数和抗球虫指数为指标对该虫株对球虫宁、地克珠利、马杜霉素、磺胺氯吡嗪、癸氧喹酯5种常用抗球虫药的抗药性进行了综合评定,分析了该地区球虫的抗药性及用药对策。结果表明,该虫株对癸氧喹酯敏感,对球虫宁、地克珠利、马杜霉素、磺胺氯吡嗪具有完全抗药性,提示目前常州地区球虫抗药性非常严重,癸氧喹酯抗球虫疗效最好,其他药物应合理使用、应慎用、减少或暂停使用。     

癸氧喹酯干混悬剂对不同地区分离球虫株的敏感性试验

分别进行癸氧喹酯对历史分离球虫株和现行临床分离球虫株的敏感性试验,结果显示,癸氧喹酯干混悬剂对历史分离球虫株和现行临床分离球虫株的敏感性较好,抗球虫指数大于180,表现出高效的抗球虫活性,能有效提高鸡只生长性能,提高饲料转化率。     

癸氧喹酯干混悬剂防治人工感染鸡球虫病的效果试验

通过对14日龄岭南黄鸡人工感染柔嫩艾美耳球虫卵囊,测定国家四类新兽药癸氧喹酯干混悬剂的抗球虫作用。研究结果表明,新兽药癸氧喹酯干混悬剂按照推荐剂量0.25g/L(15mg/L)饮水给药对鸡球虫病表现出高效的抗球虫活性,具有良好的预防鸡球虫病效果,达到100%的保护率,抗球虫指数高达202.2。     

四川部分地区鸡球虫分离株对11种抗球虫药物的耐药性调查

从四川省部分地区分离到6株鸡艾美耳球虫株,为了掌握这些虫株对11种常用抗球虫药物的耐药性情况,采用笼饲试验法(鸡体试验法),以最适抗球虫活性百分率(POAA)、病变记分减少率(RLS)、相对卵囊产量(ROP)和抗球虫指数(ACI)4项指标对结果进行综合判定。结果表明,6株鸡艾美耳球虫对癸氧喹酯、拉沙洛西钠、盐酸氯苯胍和莫能菌素为轻度耐药及以上;对尼卡巴嗪、二硝托铵、氯羟吡啶、马度米星铵和甲基盐霉素为中度耐药及以上;对复方磺胺氯达嗪钠均为重度耐药及以上。6株鸡艾美耳球虫四川株对11种受试药物均不敏感,且对大部分试验药物表现为中度或重度耐药。     

柔嫩艾美耳球虫莆田株抗药性研究

为掌握鸡场球虫抗药程度,以便制定合理用药方案,采集福建省莆田市某鸡场盲肠球虫,进行柔嫩艾美耳球虫单卵囊分离和纯化;采用鸡体试验法,设立5个用药组、1个感染不用药对照组和1个不感染不用药对照组,以病变记分减少率(Reduction of lesion sores,RLS)、抗球虫指数(Anticoccidial index,ACI)、相对盲肠卵囊产量(Relative at oocyst production,ROP)和最适抗球虫活性百分率(Percent of optimum anticoccidial activity,POAA)4项为指标,检测该球虫对癸氧喹酯、尼卡巴嗪、地克珠利、二硝托胺和氯苯胍等5种常用抗球虫药的抗药性。结果表明:该虫株对癸氧喹酯敏感,对地克珠利、二硝托胺和氯苯胍具有完全抗药性,对尼卡巴嗪为中度抗药性,说明目前莆田市球虫抗药性非常严重,癸氧喹酯可用于抗球虫病,其他药物应慎用或暂停使用。     

柔嫩艾美耳球虫盐霉素耐药株的实验室诱导

为了研究耐药性柔嫩艾美耳球虫产生耐药性的机理,本研究在实验室条件下,采用药物浓度递增的方法,以15 mg/kg为起始诱导浓度,对柔嫩艾美耳球虫盐霉素耐药性进行诱导。经过10次传代,获得了对60 mg/kg盐霉素耐药的柔嫩艾美耳球虫虫株。以抗球虫指数、最适抗球虫活性百分率、病变记分减少率和相对卵囊产量四项指标综合判定柔嫩艾美耳球虫对盐霉素的耐药性。其中抗球虫指数为156.92,最适抗球虫活性百分率为32.38,病变记分减少率为53.85,相对卵囊产量为28.17。结果显示,成功获得了柔嫩艾美耳球虫对盐霉素完全耐药的虫株,为进一步从分子水平研究球虫抗药性奠定基础。     

4种抗球虫药防制鸡艾美耳球虫的试验

挑选健康和体况相近的180羽14日龄黄羽肉鸡,随机分组,在人工感染鸡艾美耳球虫条件下,评估癸氧喹酯、马杜米星铵、尼卡巴嗪乙氧酰胺苯甲酯及甲基盐霉素的抗球虫效果,并对4种抗球虫药物进行比较,以抗球虫指数(ACI)作为药物治疗效果的综合评定指标。结果显示,各药物组的ACI分别为癸氧喹酯194.53,马杜米星铵190.15,尼卡巴嗪乙氧酰胺苯甲酯189.87,甲基盐霉素165.42,未用药的感染对照组ACI为112.23。癸氧喹酯和马杜米星铵的抗球虫效果最好,ACI>190。     

柔嫩艾美耳球虫对盐酸氟乙基硫胺素耐药性的诱导

为评估盐酸氟乙基硫胺素产生抗药性的倾向,采用药物浓度递增法,在实验条件下进行柔嫩艾美耳球虫耐药性的诱导研究。每组动物用10只快大黄肉鸡,每只鸡接种1×105个孢子化卵囊,以50 mg/kg盐酸氨丙啉和盐酸氟乙基硫胺素为起始诱导浓度连续传代,以病变记分、存活率和卵囊数三项指标综合判定耐药性。经过10次传代,盐酸氨丙啉对敏感虫株的ACI为192.6,而对耐药虫株的ACI为109.1;经过12次传代,盐酸氟乙基硫胺素对敏感虫株的ACI为197.5,而对耐药虫株的ACI为110.6,对盐酸氨丙啉耐药虫株的ACI为163.2;结果表明成功地诱导出对盐酸氨丙啉、盐酸氟乙基硫胺素完全耐药的虫株。盐酸氟乙基硫胺素产生耐药速度慢于盐酸氨丙啉,与盐酸氨丙啉有部分交叉耐药性。     

柔嫩艾美耳球虫地克珠利抗药株的实验室诱导

采用药物浓度递增法,以0．07mg／L地克珠利为起始诱导浓度连续传代,以最适抗球虫指数（POAA）、病变记分减少率（RLS）和相对卵囊产量（ROP）3项指标综合判定抗药性。经12次传代,该诱导虫株对1．5mg／L地克珠利具有完全抵抗力。试验结果表明,用实验室方法诱导柔嫩艾美耳球虫抗药株完全可行。     

复方尼卡巴嗪、马杜霉素铵对鸡艾美耳球虫临床防治效果初探

试验表明,推荐量的复方尼卡巴嗪（125mg／kg）、马杜霉素铵（5mg／kg）对E．tenella GD珠球虫抗球虫指数为194．1,对6个E．tenella 田间分离株抗球虫指数都在170以上,其抗球虫指数优于单方的尼卡巴嗪及马杜霉素组,尤其对耐药虫株。     

Efficacy of decoquinate against drug sensitive laboratory strains of Eimeria tenella and field isolates of Eimeria spp. in broiler chickens in China

The efficacy of decoquinate against Eimeria infections in broiler chickens was evaluated using two drug sensitive laboratory strains of Eimeria tenella and 20 field isolates of Eimeria spp. collected from farms in China where various anticoccidials (including maduramicin) had been used. Decoquinate (20-40 ppm in feed) and maduramicin (5 ppm) were efficacious against E. tenella laboratory strains, but decoquinate more so than maduramicin. Body weight gains of E. tenella infected chickens were significantly improved, and caecal lesions were prevented, by feeding either decoquinate or maduramicin. Decoquinate also prevented oocyst production, but maduramicin did not. Most (18/20) Eimeria field isolates were resistant to maduramicin, judged by oocyst production; decoquinate at > or =20 ppm completely controlled all 20 field isolates. Decoquinate has potential value as a broiler anticoccidial in China and other countries where it has not been previously used.     

Isolation and selection of ionophore-tolerant Eimeria precocious lines: E. tenella, E. maxima and E. acervulina

Eimeria parasites were isolated from Nanhai Guangdong province (southern China) and studied in chickens in wire cages to evaluate their drug resistance against commonly used ionophores: monensin (100 mg/kg of feed), lasolacid (90 mg/kg), salinomycin (60 mg/kg), maduramicin (5 mg/kg) and semduramicin (25 mg/kg). Chinese Yellow Broiler Chickens were infected with 40,000 crude sporulated Eimeria oocysts at 15 days of age and prophylactic medication commenced a day prior to infection. Drug resistance was assessed for each ionophore drug by calculating the anticoccidial index (ACI) and percentage optimum anticoccidial activity (POAA) based on relative weight gain, rate of oocyst production and lesion values. Results revealed that Nanhai Eimeria oocysts comprising of E. tenella, E. maxima and E. acervulina, were resistant to monensin, sensitive to both salinomycin and lasolacid and partially sensitive to maduramicin and semduramicin. By selection for early development of oocysts during passage through chickens, the prepatent time of E. tenella, E. maxima and E. acervulina were reduced by 49, 36 and 22 h, respectively. The precocious lines are less pathogenic than the parent strains from which they were selected and conferred a satisfactory protection for chickens against coccidiosis. These ionophore-tolerant precocious lines could have wider applications in the development of anticoccidial vaccines for sustainable control of coccidiosis.     

Tracing the emergence of drug-resistance in coccidia (Eimeria spp.) of commercial broiler flocks medicated with decoquinate for the first time in the United Kingdom

Decoquinate is a quinolone coccidiostat introduced during 1967 as an in-feed prophylactic for broiler chickens. Despite early drug-resistance problems and its age, the drug is still used commercially worldwide. Decoquinate here serves as a valuable model in a field study that addresses the dynamics and economic impact of the development of coccidial resistance to potent synthetic anticoccidial drugs. The results of this unique, hitherto unpublished, study on the initial emergence of resistance of avian coccidia (Eimeria spp.) to a new drug in the field may be of strategic value in the continued use of decoquinate or the introduction of new drugs. The commercial performance of the first 3-5 crops of broilers to be medicated with decoquinate on each of six farms was monitored during 14 months in 1968-1969, supplemented by assessments of the species, population dynamics and decoquinate-resistance of coccidia isolated from each farm. During the rearing of each flock in a single shed on each farm, oocysts were counted in fresh faecal samples collected on three occasions, and the species were identified by their morphology if possible, supported if necessary by the biological characteristics of infections in chickens. E. acervulina was the most common species, followed by E. mitis, E. maxima, E. tenella and E. praecox. E. brunetti occurred rarely, and E. necatrix was not found. Decoquinate-resistance was evident in several species during the rearing of the first decoquinate-medicated crop on each farm, although clinical coccidiosis did not occur. It was concluded that inherently resistant mutants of E. acervulina, E. brunetti, E. maxima, E. tenella, and probably also E. mitis and E. praecox, were selected from field populations by 6 weeks during their first exposure to decoquinate. During up to four more subsequent crops, cycling of resistant parasites stimulated host immunity, which had no obvious adverse impact on commercial performance. There was no apparent seasonal effect. A hypothesis is proposed to explain the sudden and rapid emergence of quinolone-resistance in the coccidia, and why bird health was not thereby compromised in these circumstances.     

巨型艾美耳球虫和柔嫩艾美耳球虫早熟株对8种抗球虫药的敏感试验

为检测巨型艾美耳球虫和柔嫩艾美耳球虫早熟株对常用抗球虫药的敏感性,选用地克珠利、氯苯胍、二硝托胺、癸氧喹酯、尼卡巴嗪、马杜米星、盐霉素和拉沙洛西等8种抗球虫药进行鸡体试验,通过抗球虫活性百分比（percent of optimum anticoccidial aetivity,POAA）、病变记分减少率（reduction of lesion scores,RLS）、相对卵囊产量（relative oocyst production,ROP）和抗球虫指数（anticoccidial index,ACI）4项指标进行综合评价。结果表明,巨型艾美耳球虫早熟株对8种药物敏感;柔嫩艾美耳球虫早熟株对盐霉素轻度敏感,对地克珠利、氯苯胍、二硝托胺、癸氧喹酯、尼卡巴嗪、马杜米星和拉沙洛西敏感。本研究结果可为对球虫早熟株疫苗的开发与应用提供实验依据。     

Evaluation of the efficacy of maduramacin ammonium in combination with roxarsone and avoparcin in caged broiler chickens

1. The anticoccidial activity of maduramicin ammonium (5 mg/kg food) administered alone or with roxarsone (50 mg/kg food) and/or avoparcin (10 mg/kg food) was evaluated in battery-reared broilers artificially challenged with recent field culture mixtures containing Eimeria acervulina, E. maxima and E. tenella or E. mivati, E. necatrix and E. brunetti. 2. Maduramicin ammonium exhibited a high degree of anticoccidial activity and the addition of roxarsone and/or avoparcin in food at recommended concentrations did not adversely affect the activity.