帝克珠利对鸡堆型艾美尔球虫的药效实验

球虫病是威胁养鸡业的重要疾病之一,目前对该病的防治仍主要依赖药物［１］。但耐药虫株的出现使现有许多抗球虫药物疗效降低甚至丧失。因此,除了采取轮换用药及穿梭用药等方法以减少或延缓耐药性的产生外,开发评价和应用新型抗型抗球虫药物极为重要和必要。本文报道我...     

Studies on the stage of action of lasalocid against Eimeria tenella and Eimeria acervulina in the chicken

Broiler chickens in battery pens were either fed a diet containing 100 ppm lasalocid or no drug for 24 h prior to inoculation with sporulated oocysts of Eimeria tenella or Eimeria acervulina. Different groups of birds remained on medicated feed for 24, 48, 72, 96, 120 or 144 h after inoculation. Conversely, other groups started on an unmedicated diet, were given medicated feed at different times after oocyst inoculation. Starting lasalocid medication 24 h (E. tenella) or 48 h (E. acervulina) after inoculation reduced the lesions and improved the weight gain. There was no significant difference in performance of birds after withdrawal of the drug at 48 h (E. tenella) or 72 h (E. acervulina) and thereafter. Starting lasalocid medication at 96 or 120 h did not suppress but rather reduced oocyst production.     

Sensitivity of field isolates of Eimeria species to monensin and lasalocid in the chicken

Isolates of Eimeria species obtained from broiler or from breeder farms were compared for their sensitivity to two ionophorous anticoccidial drugs, monensin and lasalocid. All of 25 isolates from broiler farms were resistant to 100 ppm monensin or 90 ppm lasalocid, while 14 of 16 isolates were resistant to monensin and seven of 16 to lasalocid from breeder farms (replacement layer and broiler breeder).     

三株柔嫩艾美球虫野外分离株的致病性分析

用每鸡4×104和8×104个孢子化卵囊的剂量感染黄羽肉雏,以临床症状、肉眼病变、平均增重、病变记分和死亡率为判定指标,对柔嫩艾美球虫EtCZ-1、EtCZ-2、EtCZ-3株的致病性进行了比较分析。结果显示:各虫株引起的临床症状和肠道肉眼病变基本相似,致病性随着感染剂量的增加而增强。各感染组的增重与对照组相比均有显著差异(P<0.50),相对增重率分别下降了74.4%～83.2%、68.7%～72.2%和70.6%～74.4%;感染后鸡出现血便的时间较一致,即第108小时开始排血便,在120h～144h达高峰;病变值和卵囊值均随着感染剂量的增加而增大;除EtCZ-1株高剂量组的存活率是90%以外,其余各组均为100%。显示3株球虫的致病性相似。     

鸡胚接种柔嫩艾美耳球虫和堆形艾美耳球虫活卵囊的免疫保护试验

给18日龄鸡胚接种一定剂量的柔嫩艾美耳球虫(Eim eria tenella)和/或堆形艾美耳球虫(E.acervulina)孢子化卵囊,出雏后在无球虫环境中笼养,1~10日龄每天收集各组粪便样本,计数克粪便卵囊数(OPG),并于14日龄时以大剂量同源孢子化卵囊攻虫,以相对增重率(RWG)、饲料转化率(FCR)、相对卵囊产量(ROP)评价免疫保护效果。结果显示,以E.tenella或E.acervulina卵囊免疫18日龄鸡胚,其卵囊排出的潜隐期及达到峰值的时间与1日龄雏鸡接种组相一致,有相似的排卵囊曲线,提示其诱导免疫的建立是在出雏后开始建立的。攻虫后各免疫组的RWG由攻虫对照组的31.9%~51.7%提高到了76.5%~83.6%,RCR由攻虫对照组的4.11~4.89改善为2.72~2.96,ROP降至4.7%~23.5%。结果表明以一定剂量E.tenella和E.acervulina卵囊单独或混合经羊膜腔免疫18日龄鸡胚都可以建立起针对出雏后14日龄同源攻虫的良好免疫保护力。比较混合免疫E.tenella和E.acervulina卵囊组与单一接种E.tenella或E.acervulina卵囊组的免疫效果发现,混合免疫组的各项指标均稍优于后者。     

Pathogenicity of Eimeria praecox alone or associated with Eimeria acervulina in experimentally infected broiler chickens

Eimeria praecox and Eimeria acervulina are two species of coccidia parasites infecting chickens, which develop in the duodenum. The purpose of this study was to evaluate the pathogenicity of E. praecox and to study interactions of this coccidium with E. acervulina. The results showed that the pathogenicity of E. praecox was related to the infective dose, and that its impact on individual weight and weight gain was significant from the lowest administered dose: 5000 oocysts per bird. No morbidity was observed, even with the highest infective dose, but faecal consistency alteration was higher with increasing infective doses. No consistent lesion was observed. When E. praecox was associated with E. acervulina with a low infective dose, performance deterioration seemed to be an additional effect of the two species. However, in the case of heavy infections, signs worsened along with duration of negative impact on growth, compared to a mono-infection.     

Energy and nitrogen metabolism of chickens infected with either Eimeria acervulina or Eimeria tenella.

1. The effects of sublethal infections of E. acervulina and E. tenella on the energy and nitrogen metabolism of groups of five broilers aged 16 d were studied for 16 d in respiration chambers. 2. The metabolisable energy content of the diet for chickens infected with E. acervulina was 0.689 of its gross energy content and N retention was 42.5 g/100 g N intake compared with 0.738 and 47.1 g respectively, in uninfected pair-fed controls. Chickens infected with E. tenella were similarly affected. 3. Efficiency of utilisation of ME by chickens infected with E. acervulina was 0.43 during the first 8 d after infection, and 0.52 during the second 8 d compared with an overall efficiency by non-infected chickens fed ad libitum of 0.73. Maintenance energy requirement of infected chickens was higher during the first 8 d after infection than during the second 8-d period. 4. Body composition measurements showed that of the total gain in weight of chickens infected with E. acervulina, only 7.5 g/kg gain was fat and 213 g/kg was protein compared with 45 g and 210 g respectively for non infected chickens fed ad libitum. 5. E. acervulina and E. tenella infections reduced the apparent digestibility of total mineral, calcium and phosphorus.     

Intestinal absorption of glycylproline in chicks infected with Eimeria acervulina.

The absorption of glycine and proline through the mid-intestines of chicks infected with Eimeria acervulina was impaired when the amino acids were presented to the mucosal surface as the dipeptide, glycylproline.     

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.     

五种不同地理株柔嫩艾美耳球虫免疫保护性比较

用五个不同地理株的柔嫩艾美耳球虫（Eimeria tenella），即：广州株、保定株、长春株、北京株、沈阳株，对12日龄雏鸡分别进行免疫攻虫。通过OPG计数，粪便计分，盲肠病变计分，增重测定，计算保护率。结果发现不同地理株球虫的免疫保护率有明显差异，广州株80．2％〉保定株73．2％〉长春株68．4％〉北京株63．8％〉沈阳株51．0％。其中广州株比其他虫株有显著保护率（P〈0．01）。免疫后的雏鸡抽血进行CD4^＋、CD8^＋T细胞检测，结果各株均能引起两种T细胞数量增加，表明CD4^＋、CD8^＋T细胞在球虫免疫中起着重要作用。     

堆型艾美耳球虫感染后组织抗氧化功能的变化

通过测定堆型艾美耳球虫(Eimeria acervulina)感染鸡心脏、肝脏、脾脏、肺脏和肾脏组织中超氧化物歧化酶(SOD)、丙二醛(MDA)、谷胱甘肽过氧化物酶(GSH-Px)和过氧化氢酶(CAT)的水平,研究E.acervulina感染对雏鸡的组织抗氧化功能的影响。结果表明,雏鸡在感染E.acervulina后,早期各组织SOD活性均低于对照组水平,但很快都又恢复到正常对照组水平;各组织中MDA含量均高于对照组水平;心脏、肝脏和脾脏中CAT活性在感染后下降,肺脏和肾脏中CAT活性在感染后升高;各组织GSH-Px活性在感染后均有不同程度的下降。表明病理氧化应激参与了球虫感染过程,损伤了机体的氧化平衡。     

巨型艾美耳球虫不同地理株交叉免疫保护性研究

筛选出与巨型艾美耳球虫(E.maxima)山东分离株(Msd)免疫原性差异大的早熟弱毒株,为研制具有良好免疫原性的高效多价鸡球虫疫苗提供理论依据。4日龄雏鸡免疫E.maxima山东分离早熟株(PMsd),免疫后7 d分别攻击E.maxima Msd、上海分离株(Msh)、北京分离株(Mbj)、山西分离株(Msx);14日龄雏鸡分别免疫E.maxima Mbj和Msx,免疫后7 d,Mbj免疫组分别攻击Msh和Msx,Msx免疫组分别攻击Msh和Mbj。免疫PMsd攻击Msd组鸡只达到良好的免疫保护,而免疫PMsd攻击Msx组鸡只除病变记分减少率(28.6%)高于Mbj组(23.8%)外,相对增重率(74.3%)、卵囊减少率(9.7%)、抗球虫指数(159.3)均低于其他各组;免疫Msx攻击Mbj和Msh组鸡只卵囊减少率、抗球虫指数、相对增重率均大于免疫Mbj攻击Msx和Msh组。4种不同地理株的巨型艾美耳球虫中,Msx与Msd的免疫原性差异最大,且较Mbj更为广谱。     

NO对接种Eimeria acervulina雏鸡体液免疫水平的影响

用1日龄黄羽肉鸡研究了一氧化氮(NO)对接种Eimeria acervulina雏鸡体液免疫水平的影响.试验设3个对照组(免疫对照组、感染对照组、空白对照组)和3个试验组(L-精氮酸组、L-氨基胍组、NG亚硝基-L-精氦酸甲基酯组),每组8只鸡.免疫程序为,7日龄时初免,接种卵囊3×103个/只;14日龄时二免,接种卵囊5×103个/只;21日龄时三免,接种卵囊1×104个/只;28日龄时四免,接种卵囊3×106个/只.感染对照组用于判断本试验所采用的免疫程序是否成功,该组鸡仅在28日龄时感染卵囊1次,剂量为3×106个/只.3个对照组从7日龄开始直至扑杀当日连续口服生理盐水0.5 mL/次,2次/d;3个试验组从7日龄开始直至扑杀当日分别口服5 g/L L-精氨酸溶液或3 g/L L-氨基胍溶液或6 g/L NG-亚硝基-L-精氨酸甲基酯溶液,0.5 mL/次,2次/d.38日龄时扑杀全部试验鸡,取血清样本用ELISA法测定抗体水平;取十二指肠样本进行肠道病变记分.试验结果表明,给免疫E.acervulina的雏鸡每日口服NO生成底物L-精氨酸、可增加其血清抗体水平(P<0.05);而口服诱导型NO合成酶(iNOS)抑制剂氨基胍和原生型NO合成酶(cNOS)抑制剂NG-亚硝基-L-精氨酸甲基酯,可明显降低其血清抗体水平(P<0.01).上述结果表明,NO具有提高E.acervulina免疫雏鸡体液免疫水平的作用,且由2种NO合成酶(NOS)催化生成的NO均参与了此过程.     

Influence of coccidiosis on growth rate and feed conversion in broilers after experimental infections with Eimeria acervulina and Eimeria maxima

Under experimental conditions, the effects of subclinical Eimeria (E.) acervulina and E. maxima infections on growth and feed conversion in broilers of different ages were analysed. It was concluded that infection with E. acervulina and E. maxima led to a process which was independent of the age at which the birds were infected. The infection adversely affected growth and feed conversion for 2 to 3 weeks, followed by a recovery period of 2 to 3 weeks when compensatory growth took place. From this study it may be concluded that subclinical coccidiosis in the first weeks of life and in the last week of life of broilers does not lead to appreciable damage on growth and feed conversion. Since coccidiosis cannot be avoided in practice, systems in which broilers contact subclinical coccidiosis either in the first weeks of life or in the last week of life should be aimed for. It is suggested that in a coccidiostat programme an efficient anticoccidiosis agent is particularly desirable in the 3rd and 2nd week before slaughter. Examinations performed one week or less before slaughter can hardly be justified, on the grounds that there is a risk of a negative effect on growth an feed conversion due to subclinical coccidiosis.     

Pharmacodynamic evaluation of a reference and a generic toltrazuril preparation in broilers experimentally infected with Eimeria tenella or E. acervulina

1. The aim of this study was to investigate the effects on pigmentation, faecal oocyst output, immune responsiveness and reactive oxygen species (ROS) generation following treatment with either the reference toltrazuril (Baycox) or a generic preparation (gen-TTZ), during an experimental Eimeria tenella (Et) or E. acervulina (Ea) infection of 210 Ross broiler chickens.

2. Results showed a significant difference on the anticoccidial efficacy 6 d after treating infected animals with Baycox (Et: 99.69% and Ea: 99.52%) or gen-TTZ (Et:85.71% and Ea 81.81%).

3. Gen-TTZ-treated animals were less strongly carotenoid-pigmented than Baycox-treated broilers. Mean plasma carotenoid concentrations were significantly higher in groups treated with Baycox than in broilers given gen-TTZ.

4. Treatment of animals with Baycox led to a significant decrease in ability of the peripheral blood mononuclear cells to produce ROS in contrast to gen-TTZ-treated groups. Baycox, but not generic toltrazuril, increased IL-10 and decreased tumour necrosis factor alpha (TNF-α) concentrations in chickens infected with E. tenella and E. acervulina.

5. It is suggested that differences in anticoccidial efficacy may be observed when using a generic toltrazuril product. Hence, in addition to plasma profiles of drugs, standardised clinical control tests may be necessary for generic formulations, particularly if other parameters are important to achieve a better control of coccidiosis.     

Absorption and deposition of xanthophylls in broilers challenged with three dosages of Eimeria acervulina oocysts

1. An experiment was designed to evaluate the effect of different doses of oocysts of Eimeria acervulina on intestinal absorption and skin deposition of xanthophylls (XAs) in broilers.

2. A total of 192 broiler chickens were randomly assigned to 4 groups: an uninfected control group and three groups inoculated with either 1 × 10², 1 × 10⁴ or 1 × 10⁵ sporulated oocysts of E. acervulina by gavaging at 21 d. There were 4 replicate pens (2 male and 2 female) per group.

3. Plasma xanthophyll (PX) and skin yellowness (SY) were measured in live birds weekly. At 42 d of age, SY was measured in the breast and abdomen after chilling and in the breast 24 h post-processing on refrigerated carcasses.

4. In general, in all challenged treatments, and for the duration of the study, the average PX decreased by 0.02 μg/ml (R² = 61.6%) for every 1000 inoculated oocysts, whereas PX increased by 1.26 μg/ml/d in uninfected birds.

5. The average SY in live birds from 21 to 42 d of age decreased by 0.019 b*/every 1000 oocysts administered, while SY of uninfected controls increased by 0.57 b*/d. It was also noted that in all treatments females had a greater SY (6.17 b*) than males for the duration of the study. The SY of the breast and abdomen was correlated (r = 0.76) in chilled carcasses. Breast SY in 24 h refrigerated carcasses was greater in the control group and for female birds.

6. Oocyst excretion was different between inoculated treatments only on 7 d post-inoculation (PI). Coccidia lesion scores in the duodenum averaged 1+ in infected birds and 2+ in birds given the highest oocyst dose.     

Energy and nitrogen metabolism of chickens subjected to infection and reinfection with Eimeria acervulina.

1. The effects of E. acervulina on energy and nitrogen metabolism were studied in respiration chambers on four groups of four broilers aged 16 d: group C was infected with 1.1 x 10(6) oocysts/bird on day 1 and fed ad libitum, while groups A, B and D were pair-fed to group C to day 16 of the experiment. On day 17, groups A and C were given 5.0 x 10(6) oocysts/bird and fed ad libitum, while group B was pair-fed to group A and group D was pair-fed to group C to the end of experiment on day 32. 2. Dietary ME as a proportion of gross energy (0.68) and N retention (42 g/100 g N intake) were reduced in the infected group C compared with pair-fed controls (0.75 and 49 g, respectively) for the period 1 to 16 d. Subsequent challenge of group C saw no effects on the two variables, but metabolisability (0.65) and N retention (33 g) were significantly reduced in group A when infected for the first time on day 17. 3. The daily heat production and food intake of group A infected for the first time with E. acervulina on day 17, and group B, their pair-fed controls, were reduced during days 20 to 25 but no such reductions were observed in group C, receiving a challenge dose of E. acervulina, and group D, non-infected pair-fed to group C. The efficiency of utilisation of ME for growth of groups C and D was 0.60 over the 17 to 32 d period. 4. Challenge of immune birds did not affect the apparent digestibility of total minerals, calcium and phosphorus.     

Effects of Natustat supplementation on performance, feed efficiency and intestinal lesion scores in broiler chickens challenged with Eimeria acervulina, Eimeria maxima and Eimeria tenella

The effects of dietary supplementation of Natustat™, a propriety plant derived product (Alltech Inc., KY, USA) and Salinomycin, on performance, feed efficiency and intestinal lesion scores were observed during two Eimeria challenge trials in broiler chickens. In the first trial chickens were challenged with Eimeria sp. via infecting the litter with a known amount of Eimeria oocysts. In the second trial the source of the Eimeria challenge was the litter from the first trial and the same treatment groups were assigned to the same pens as in the initial trial.

Birds were placed 55 per pen with seven pens per treatment. Performance parameters were recorded on days 21 and 42 during both trials. Intestinal lesion scores were assessed on days 14 and 21 during Trial 1 and on day 21 during Trial 2. Average weight gain and feed conversion ratios were significantly improved in the Natustat™ and Salinomycin treatment groups when compared to the non-supplemented infected group. Furthermore, lesion scores were lower on all sampling days in the Natustat™ and Salinomycin groups when compared to the non-supplemented group. However, only lesions associated with Eimeria tenella were significantly lowered by Natustat™ and Salinomycin supplementation.

Natustat™ and Salinomycin were equivalent in alleviating the negative performance effects associated with coccidiosis challenge. In summary, Natustat™ has the potential to be used as a natural alternative to chemotherapeutic drugs for Eimeria control.