Coccidiosis control with toltrazuril in conjunction with anticoccidial medicated or nonmedicated feed

A 42-day broiler floor pen study was conducted comparing the anticoccidial efficacy of toltrazuril (Baycox) as a stand alone treatment and as an additional treatment to in-feed anticoccidial programs. Toltrazuril was administered on days 18 and 19 in the drinking water at 7 mg/kg of body weight. The treatments were 125 ppm nicarbazin (days 0-14) to 66 ppm salinomycin (SAL) (days 15-35) with and without toltrazuril, SAL (days 0-35) with and without toltrazuril, nonmedicated (NM) to SAL with toltrazuril, and NM with and without toltrazuril. The controls were NM noninfected and infected. The treatments were replicated in five blocks of eight pens each in a randomized complete block design. All withdrawal feed was nonmedicated. On day 14, birds, except noninfected, were exposed to coccidial oocysts (Eimeria acervulina, Eimeria maxima, and Eimeria tenella) seeded litter. On days 21, 28, 35, and 42, birds and feed were weighed, four birds per pen were coccidial lesion scored, and litter oocyst counts were performed. The coccidial infection in the NM infected treatment caused a significant (P < 0.05) coccidiosis infection. Coccidiosis was moderately controlled in the anticoccidial treatment birds without toltrazuril. Performance in the NM with toltrazuril was equal to or better (P < 0.05) than the anticoccidial programs without toltrazuril. Toltrazuril was equal to the noninfected birds in performance. Toltrazuril most completely eliminated all coccidial lesions and dramatically reduced oocyst shedding. The performance data, lesion scores, and oocyst counts showed that a 2-day treatment with toltrazuril successfully controlled the coccidiosis with no relapse of infection. Toltrazuril can thus be used for supplemental control with in-feed anticoccidials or as a primary anticoccidial with nonmedicated feed.     

鸡球虫微囊型疫苗的研制及免疫效果

研制了微囊型鸡球虫疫苗并对其免疫效果进行探讨。结果表明,强毒微囊组获得的饲养效果最好,其相对增重率和相对饲料转换率分别为104.8%和100%;弱毒水剂组为74.1%和136%,而弱毒微囊组为49.4%和188%。强毒微囊组对球虫病的控制效果也明显好于其他组,其发病率、病变记分、血便记分分别为20%,6分和3分,而弱毒水剂组和弱毒微囊组分别为40%、10分、7分和50%、18分、8分。所研制的这种新型微囊球虫疫苗,具有使用方便,节省人力物力;疫苗大小适中,流动性好容易与小鸡饲料混合均匀等优点。由于微囊型球虫疫苗投服方便,因此能适合各种规模的鸡场使用,也适合鸡场进行多次或长期免疫使用。这种微囊剂型球虫疫苗的进一步完善和推广应用,可为我国鸡球虫病的免疫预防提供新的剂型。     

细菌CpG DNA对鸡球虫弱毒苗Immucox的免疫增强效应

采用细菌CpG DNA作鸡球虫弱毒苗Immucox佐剂以探索其应用的可行性。将制备的细菌CpG DNA和球虫疫苗Immuncox单独或联合免疫接种肉鸡,第2次免疫后7d进行攻虫,口服接种柔嫩艾美儿球虫孢子化卵囊105个/只。感染后第7天,对试验动物进行称重并屠杀,分别观察盲肠病变积分、每克粪便卵囊排出数和体增重情况。结果:在相对增重方面,细菌CpG DNA+疫苗组高于感染非免疫组、疫苗组和CpG组,且与它们均差异显著(P<0.05);在卵囊排出总数和盲肠病变平均记分方面,细菌CpG DNA+疫苗组低于感染非免疫组、疫苗组和CpG组,且与之比较差异显著(P<0.05);在抗球虫综合指数方面,疫苗+细菌CpGDNA组达到172。结果表明用细菌CpG作鸡球虫弱毒苗Immucox的佐剂可提高该疫苗免疫保护效果。     

Safety of the attenuated anticoccidial vaccine ‘Paracox’ in broiler chickens isolated from extraneous coccidial infection

A trial was carried out in 1-day-old broiler chicks raised for 54 days in floorpens under simulated commercial conditions, but isolated from all extraneous virulent coccidial infections, to demonstrate the safety of Paracox attenuated vaccine administered at the recommended dose when chicks were 7 days old. The vaccine did not adversely affect the water consumption, faecal moisture or litter condition of the broilers. Recycling of the attenuated coccidia occurred in vaccinated birds, oocysts being present in the litter between 5 and 33 days after vaccination; a single peak of oocysts was detectable 5 or 12 days after vaccination. Unvaccinated medicated control birds did not produce oocysts, indicating freedom from both between-pen contamination by the vaccine and invasion of the chicken-house by extraneous coccidial infection. A small proportion (4%) of vaccinated birds had mild coccidial lesions when sampled at 26, 33 or 40 days after vaccination. Despite this, the vaccinated birds performed better than control (unvaccinated, nicarbazin-treated) birds and there was no post-vaccinal check in their weight gain. Their mean finishing weight was 10.4% greater, their food conversion ratio 7.2% lower and their mortality 44.4% lower than the unvaccinated control birds, reflecting the safety of Paracox vaccine.Abbreviation FCR food conversion ratio     

Effect of route of vaccination on the prevention of infectious laryngotracheitis in commercial egg-laying chickens

Commercial egg-laying chickens were vaccinated for infectious laryngotracheitis (ILT) with one of five commercially available vaccines (designated A, B, C, D, and E) on five separate farms by either eyedrop (e), spray (s), or double dose in the water (w) method. Groups were identified by the vaccine designation and the method of vaccination. Birds from the test groups were transferred to an isolation facility and challenged intratracheally 3 wk after vaccination. The remaining birds were given a second vaccination with the original chicken embryo origin vaccine by spray or a chicken embryo origin vaccine if the first vaccine was of tissue culture origin. After challenge, birds were monitored for clinical signs. Those surviving were euthanatized on day 6 postchallenge, and tissues and blood were collected for histopathology, virus isolation, and serology. On the basis of histopathology and enzyme-linked immunosorbent assay (ELISA) results, after one vaccination, all chickens given vaccines by eyedrop were provided better protection than nonvaccinated controls (CTLs). Birds in groups Bs and Ds had lower microscopic lesion scores whereas only birds given Bs had higher ELISA titers than CTLs. Birds in groups As and Cs and groups Bw birds taken from the rear of the barn (r) had microscopic lesion scores that were no different from those of CTLs. These same birds in addition to vaccine Ds had ELISA titers no different from those of CTLs. Of all vaccines, only A given by eyedrop or spray produced higher virus isolation titers than those of CTLs. The remainder of the vaccines produced virus isolation titers that were no different from those of CTLs. After two vaccinations, all groups had lower microscopic lesion scores than CTLs. Only Bw birds from the middle of the barn Bs, EeDs, and AsAs had virus isolation results that were higher than those of CTLs. Only groups BwrBs, CsCs, and DsDs had ELISA titers no different from those of controls. These results suggest that a priming vaccination followed by a booster dose offers better protection against ILT than a single vaccination alone. Vaccine application by eyedrop provides more uniform protection if only one vaccination is given, whereas spray vaccination may serve as an alternative method of vaccination for birds receiving two doses of vaccine.     

Coccidiosis immunization: effects of mushroom and herb polysaccharides on immune responses of chickens infected with Eimeria tenella

An experiment was conducted to investigate the effects of polysaccharide extracts (E) of two mushrooms, Lentinus edodes (LenE) and Tremella fuciformis (TreE), and an herb, Astragalus membranaceus (AstE), on the immune responses of chickens infected with Eimeria tenella. A total of 180 broiler chickens were assigned to nine groups: three groups were fed with each of the extracts (LenE, TreE, and AstE), three groups were fed with the extracts and immunized with live oocyst vaccine (LenE+V, TreE+V, and AstE+V), a group was immunized with the vaccine only, and there were two controls (E. tenella-infected and noninfected groups). The oocyst vaccine was given at 4 days of age, and the extracts (1 g/kg of the diet) were supplemented from 8 to 14 days of age. At 18 days of age, all birds except those in the noninfected group were infected with 9 x 10(4) sporulated oocysts. The results showed that at 7 days postinfection (p.i.), birds fed the extracts without vaccination had lower body weight (BW) gain than those given the vaccine only. However, the extracts in conjunction with the vaccine significantly enhanced BW gain of the infected chickens compared with the vaccine group. Of the three extracts, LenE and TreE showed a better growth-promoting effect. The extracts largely increased oocyst excretion of droppings during the primary response postvaccination. The cecal peak oocyst output and lesion scores measured at 7 days p.i. were higher in the groups fed the extracts than in the group immunized with the vaccine only, whereas those of the groups fed with the extracts and immunized with the vaccine were not significantly different from the vaccine group. Of the three extracts, both LenE- and AstE-fed groups showed lower cecal oocyst output. Thus, as compared with the extracts, the live, attenuated vaccine showed better results with significantly increased immune response in coccidial infected birds. The polysaccharide extracts may prove useful against avian coccidiosis, and, particularly when they are used in conjunction with vaccine, they have shown preliminary promise against the experimental coccidial infection.     

免疫增强剂对鸡球虫免疫保护力的作用

选取免疫增强剂卡介苗（BCG）与黄芪多糖（APS）以比较不同用法、不同攻虫强度下其增强鸡球虫免疫保护力的效果。结果表明：BCG和APS均具有明显的免疫促进作用，能更有效地抵抗5万和25万E.Tenella卵囊的攻击，但BCG效果优于APS；BCG和APS大剂量或重复使用效果均不理想；BCG的最佳使用方法为：以0.025ml／只的剂量于球虫免疫前7d使用1次。     

Growth of Salmonella typhimurium in the caecum of gnotobiotic chickens with Eimeria tenella

Gnotobiotic chickens infected with Eimeria tenella (5 X 10(4) oocysts per bird) received an oral inoculation of 100 Salmonella typhimurium two, four, six or eight days after coccidial infection at four days old. When S typhimurium was given two or four days after E tenella infection, S typhimurium counts in the caecal contents were similar to the counts in birds infected with S typhimurium alone. When S typhimurium was given six or eight days after E tenella infection, counts of the organism were significantly greater than with S typhimurium infection alone. There were no differences in the number of chickens positive for S typhimurium in the caecal contents, bile, liver and spleen between the two groups.     

Inhibitory effect of dietary anacardic acid supplementation on cecal lesion formation following chicken coccidial infection

Two experiments were conducted to determine the effects on male chicken performance of anacardic acid and cashew nut shell oil as feed supplements during an experimental coccidial infection. Seven-day-old chicks wer e fed a corn-soybean diet containing anacardic acid at 0, 0.4 or 0.8% (Experiment 1), or cashew nut shell oil at 0, 0.1, 0.2 or 0.4% (Experiment 2) for 10 days. On the third day of each experiment, half of the birds fed each diet were individually inoculated orally with 2 × 10³ or 5 × 10⁴ (Experiment 1) and 1 × 10⁴ or 1 × 10⁵ (Experiment 2) Eimeria tenella oocysts. In Experiment 1, body weight gain and cecal length decreased significantly according to the level of oocyst inoculation, while oocyst production per cecum (log value) and cecal lesion score significantly increased. Dietary anacardic acid supplementation had no effect on these parameters except for that of lesion score, which was improved (i.e. decreased) by anacardic acid supplementation of 0.8% at the inoculation level of 2 × 10³ oocysts, and of 0.4 and 0.8% for the higher inoculation (5 × 10⁴ oocysts). Results of Experiment 2 also showed that cashew nut shell oil affected neither cecal length nor oocyst production per cecum (log value) at either of the inoculation levels, but the lesion score was improved by cashew nut shell oil supplementation at 0.2 and 0.4% in the diet at the inoculation level of 1 × 10⁴ oocysts and at 0.4% for the higher inoculation. The present study provides the first evidence of the reducing effects of anacardic acid and cashew nut shell oil on the severity of cecal lesions in chickens during an experimental coccidial infection.     

Effects of Eimeria brunetti infection and dietary zinc on experimental induction of necrotic enteritis in broiler chickens.

Broilers infected with Eimeria brunetti and given dietary zinc were examined for experimental induction of necrotic enteritis. Inoculation with sporulated E. brunetti oocysts at 7 days of age was followed by 5 consecutive days of oral inoculation with cultured Clostridium perfringens. Feed was supplemented with zinc at 1000 ppm. Upon necropsy of broilers 6 days after coccidial inoculation, necrotic enteritis was found in 20% (2/10) of birds given both organisms and dietary zinc. Coccidial lesion scores were also highest in that group. Birds infected with E. brunetti and C. perfringens with no dietary zinc had significantly higher coccidiosis lesion scores (P less than 0.05) than groups inoculated with E. brunetti only, regardless of zinc supplementation. Alpha toxin levels in intestinal contents were low in groups infected with both organisms, regardless of zinc supplementation. Zinc was tested for effects of alpha toxin production in vitro. In the mid-log phase (6 hours incubation), a high level of alpha toxin was produced in zinc-supplemented media, but this was lost quickly in the presence of trypsin. Addition of zinc partly protected the toxin from the action of trypsin.     

The impact of traditional management on seasonal internal parasite burdens and productivity of indigenous Tswana goats in southern Botswana

Data collected monthly over a period of two years were live weight, packed cell volume (PCV), nematode faecal egg counts (FECs) and coccidial oocyst counts from faecal analyses for 100 mixed age (3-7 years) indigenous Tswana does. The aims of this experiment were to determine seasonal FECs and coccidial oocysts in these goats and quantify the relationships of these burdens to liveweight and PCV. FECs significantly (P < 0.05) varied with season, with the warmer seasons viz spring, summer and autumn having higher log (x + 1) parasite burdens than the cooler winter, while seasonal trends for coccidial oocysts were not obvious. PCV was also significantly (P < 0.05) lower in the warmer seasons than winter. FECs and coccidial oocysts in all seasons were less than the mean log (x + 1) of 3.3 inferred to reduce production in small stock. Correlation coefficients were strongly negative: -0.95 for FECs and liveweight and -0.84 for FECS and PCV, indicating that these worms had a negative impact on productivity. A further study should be conducted to quantify the effects of controlling these parasites during the warm seasons on productivity.     

The development of eimerian infections during the first eight months of life in unweaned beef calves in a dry tropical region of Australia

The development of coccidial infections in 21 free-ranging, unweaned beef calves from birth to 8 months was investigated by examining faecal samples for oocysts. Most calves commenced shedding oocysts within a month of birth, and had shed all nine species identified by 3-4 months. Oocysts were shed by three calves as young as 12 and 13 days. The oocysts species shed earliest, and the commonest thereafter, were Eimeria bovis, E. ellipsoidalis and E. zuernii. Although several oocyst counts between 5.0 X 10(3) and 114.0 X 10(3)g-1 of faeces of these potentially pathogenic species were recorded there was no clinical disease. Some calves shed oocysts approximately four times more frequently than others, and individual species counts greater than or equal to 5.0 X 10(3)g-1 were confined to 10 of the calves. Intermittent oocyst shedding continued throughout the study with a similar distribution of oocyst species from all calves.     

Effect of infection with mixed Eimeria species on T cells and T regulatory cell properties

An experiment was conducted to study the effect of a mixed Eimeria infection on chicken regulatory T cell (Treg) percentages, T-cell percentages, cell proliferation, and cytokine mRNA amounts. Specific-pathogen-free white leghorn birds were raised in battery cages and were challenged with and without coccidial oocysts at 21 d of age. At 6 d post challenge, birds inoculated with coccidial oocysts shed an average of 1.5 × 10⁴ oocysts/gram of feces. At d 6 post challenge, both CD4⁺ and CD8⁺ cell percentages in the cecal tonsil were significantly (P < 0.01) increased in challenged birds compared to the control. At d 11, CD4⁺ cell percentages in the cecal tonsil were higher in the control birds. At 6 d post challenge there was a 6-fold increase (P = 0.18) in IL-10 mRNA content in the cecal tonsils of infected birds compared to the control. At 11 d post challenge there was a 4-fold increase (P = 0.09) in IL-10 mRNA content in the infected birds’ cecal tonsils. At 11 d post challenge there was half as much (P = 0.10) IFN-γ mRNA content in the spleen of infected birds compared to the control. At 6 d post challenge, the CD25 depleted cecal tonsils of infected birds had increased proliferation (P < 0.05) compared to the control. It could be concluded that a mixed Eimeria infection causes an up-regulation of IL-10, Tregs, and CD4⁺ cells in the cecal tonsils during the late stages of infection.     

A survey of helminth parasites in backyard flocks in Michigan by litter examination

The prevalence of parasitic infections in backyard flocks was surveyed using litter samples from 74 pens located on 12 farms in central lower Michigan. Eight species of birds were represented. Two methods of litter examination (a sucrose flotation technique and a multiple washing/ZnCl2 flotation) were compared; the sucrose flotation technique was found to be more useful and was used in the survey. The following parasites eggs/oocysts were observed; ascarid-type eggs (in 34 pens from nine farms), Capillaria eggs (in 30 pens from nine farms), Strongyloides eggs (in nine pens from five farms), Syngamus eggs (in five pens from four farms), and coccidial oocysts (in 40 pens from 10 farms). Contamination of litter with ascarid-type eggs, Capillaria eggs, and coccidial oocysts was commonly found, irrespective of bird species. The contamination level in pens with more than one bird species was lower than in pens with a single species. The relatively high contamination rate may be an indication of the risk of parasitic disease in birds that are not raised under controlled conditions in confinement.     

Sampling broiler house litter for coccidial oocysts.

1. A method of sampling the surface litter of commercial broiler houses for laboratory estimation of numbers of coccidial oocysts is described. 2. The resulting estimates can be regarded as indices of the total number of oocysts present in the house at the time of sampling. 3. Using material from a variety of sources it was shown that reliable estimates for many practical purposes can be achieved with few samples, unless the birds are less than 3 weeks old. 4. Oocyst numbers usually reached a peak 4 to 5 weeks after introduction of the birds and then rapidly declined in the next few weeks.     

Reduced incidence of Clostridium perfringens-associated lesions and improved performance in broiler chickens treated with normal intestinal bacteria from adult fowl

The dosing of young chicks with cultures of normal gut flora has been termed "competitive exclusion" (CE). This study was undertaken to examine, under field conditions, the effect of CE treatment on counts of intestinal Clostridium perfringens (CP) and on the occurrence of CP-associated disease in broiler chickens. A farm having recurrent CP-associated health problems was selected as study site. The study comprised four broiler houses, with one treated and one untreated flock per house. Treated birds were sprayed with the CE product Broilact upon arrival at the farm. All flocks were offered feed containing the ionophorous anticoccidial agent narasin. The feed did not contain growth promoters. Treatment was associated with positive but statistically nonsignificant effects on gut health. Delayed intestinal proliferation of CP and delayed appearance of CP-associated gut lesions were found in CE-treated flocks. This delay was associated with improved production performance at slaughter.     

柔嫩艾美耳球虫早熟株免疫剂量研究

为了确定柔嫩艾美耳球虫（Eimenatenella）早熟株合适的免疫剂量,本文设立7个早熟株免疫攻虫组、1个不免疫攻虫组和1个不免疫不攻虫组,免疫组的免疫剂量为孢子化卵囊100、200、400、600、800、1000和2000个／羽,经嗉囊感染,7日龄首次免疫,14日龄以同等剂量进行第二次免疫,21日龄以8×10^4个／羽的同源母株进行攻虫,28日龄结束试验,以存活率、增重、肠道病变记分、血便数量、卵囊减少率为观测指标。对免疫保护效果较好的3个免疫剂量进行重复试验,同时设置商品化球虫疫苗对照组,免疫方法、试验周期、试验指标同第一批试验。结果显示：攻虫后,不免疫攻虫组出现5％死亡,而各免疫组来出现死亡;各免疫组卵囊减少率在61．57％～69．52％;200～2000免疫组的增重与不免疫不攻虫组差异不具备显著统计学意义（P〉0．05）;600～2000免疫组的肠道病变记分和血便数量均明显少于不免疫攻虫组（P〈0．05）。用600、800和1000进行重复试验,三个免疫组攻虫期间均来出现死亡,而不免疫组和疫苗对照组均出现5％死亡;三个免疫组的增重均明显高于不免疫攻虫组和疫苗对照组（P〈0．05）;早熟株免疫组的肠道病变记分和血便数量明显低于不免疫攻虫组（P〈0．05）,而疫苗对照组与不免疫攻虫组的相当（P〉0．05）;卵囊减少率在66.30％-78．75％,高于疫苗对照组的51．82％。结果表明,该柔嫩艾美耳球虫早熟株保持了良好的免疫原性,不同免疫剂量均能诱发鸡产生免疫保护力,其中600、800和1000个／羽的免疫效果均优于疫苗对照组,可考虑以600个／羽作为该早熟株在疫苗制备中的推荐免疫剂量。     

Necrotic enteritis-producing strains of Clostridium perfringens displace non-necrotic enteritis strains from the gut of chicks

We inoculated broiler chicks with mixtures of Clostridium perfringens strains to investigate the single strain dominance observed in natural cases of necrotic enteritis (NE) [Nauerby, B., Pedersen, K., Madsen, M., 2003. Analysis by pulsed-field gel electrophoresis of the genetic diversity among Clostridium perfringens isolates from chickens. Vet. Microbiol. 94, 257-266]. Pre-inoculation bacteriologic culture of chick intestines yielded up to six pulsed-field gel electrophoresis (PFGE) types of C. perfringens. Birds developed typical NE lesions in response to administration (2x per day for 4 days) of a combined inoculum comprising one NE strain (JGS4143, PFGE pattern 8) and four non-NE strains (from piglet necrotizing enteritis, chicken normal flora, human gas gangrene, and bovine neonatal enteritis). After inoculation commenced, only the NE strain was recovered through the first post-inoculation day, in spite of intense efforts to recover pre-challenge flora strains and the other challenge strains. Thereafter, pre-inoculation and previously undetected PFGE types were found, and JGS4143 became undetectable. Birds inoculated simultaneously with five NE strains (from disease in chickens or turkeys, and including JGS4143) also developed lesions, but again only JGS4143 was recovered through the 1st day post-challenge. At that time, birds began to be repopulated with pre-challenge PFGE types. Two NE strains (JGS4143 and JGS4064) produced bacteriocins, which inhibited each other and normal flora strains (n=17), while normal flora strains inhibited neither NE strains nor each other. Thus, it appears that naturally occurring dominance of the gut by NE strains can be reproduced experimentally. Bacteriocins directed against normal flora could possibly provide the necessary advantage, although inhibition of one NE strain by another suggests that other factors may be partially or completely responsible for the dominance.     

The effect of subclinigal infections with Eimeria praecox and Eimeria tenella on pigmentation and vitamin a absorption in broilers

Broilers were fed for the first 5 weeks on a starter ration containing 20 g of xanthophylls/ton. They were then divided into uniform groups and fed on either a broiler finisher ration supplying 30 g xanthophylls/ton or one supplying 20 g xanthophylls/ton and supplemented with 2.5 g canthaxanthin/ton. Six groups from each dietary regime were given 10,000 sporulated oocysts of E. praecox, daily for 5 d, six with 5000 sporulated oocysts of E. tenella daily for 5 d while the remaining six groups served as uninfected controls. All birds were housed in cages with solid floors to aid in recycling the infections over the 3‐week test period.

The resulting subclinical E. praecox and E. tenella infections, regardless of dietary treatment, caused slightly reduced weight gains and slightly impaired food conversions. Shank and breast skin visual scores, plasma and toe‐web carotenoids and liver vitamin A levels were not depressed as a result of either coccidial infection.     

Clinical selection criteria for secondary examinations of the health-status of broiler flocks.

Results of post-mortem and laboratory examinations of broilers sampled randomly or selected by clinical symptoms were compared. The male:female-ratio was in all cases nearly equal for randomly sampled and selected birds. Regarding post-mortem findings, differences dependent on selection criteria were observed: in randomly-sampled birds the frequency of breast-blisters and plantar inflammations was higher than in selected broilers, whereas in the latter osteodystrophy and bursal atrophy were seen more frequently. Alterations of joints and tendon-sheaths caused by a reovirus-arthritis in one flock were seen in same frequency in randomly sampled and selected birds, respectively. Parasitological examinations revealed the highest coccidial lesion scores in selected birds with lameness or slightly retarded growth but when dwarfism birds were included into calculations, there was no significant difference among both groups. Results of bacteriological and serological examinations showed no differences between the groups.