Long-term effect of toltrazuril on growth performances of dairy heifers and beef calves exposed to natural Eimeria zuernii and Eimeria bovis infections

The long-term effects of a toltrazuril treatment against natural Eimeria bovis and/or Eimeria zuernii infections were investigated in comparison with diclazuril and untreated controls on two dairy (Italian Friesian breed) and two beef (Chianina breed) farms. At each trial site, 30 calves were allocated into three groups of 10 calves each: T (treated with toltrazuril), D (treated with diclazuril) and C (left untreated). For 40 weeks post-treatment, the calves were weighed and examined clinically and parasitologically. The oocyst counts as well as the number of scour days were significantly lower in the T group than in the D and C groups. Final bodyweights and body condition scores of the T group exceeded those of groups C and D. The results confirmed that toltrazuril was highly efficacious, safe and provided productive benefits in dairy and beef calves.     

Metabolism and growth in housed calves given a morantel sustained release bolus and exposed to natural trichostrongyle infection

Three groups of calves, previously grazed on permanent pastures contaminated with bovine trichostrongyle (Ostertagia and Cooperia species) infective larvae, were housed from October to May. During the grazing season one group had received fenbendazole at fortnightly intervals to suppress trichostrongyle infections, one received a morantel sustained release bolus before grazing to limit trichostrongyle contamination of the pasture, and the control group was only medicated when heavy infections caused clinical type 1 ostertagiasis. Digestibility of the whole diet was poorer in the control cattle, particularly for dry matter, crude protein and energy fractions. Balance studies conducted throughout the winter housed period showed that both increased faecal and urinary nitrogen outputs in the control animals contributed to a significantly reduced overall nitrogen retention. The effects were most apparent during clinical type 2 ostertagiasis, which occurred in March in the control group.     

Dynamics of Eimeria oocyst excretion in dairy calves in the Province of Buenos Aires (Argentina), during their first 2 months of age

Clinical coccidiosis is associated with high fecal contamination and stress situations, mainly in animals under 1 year of age. Artificially fed dairy calves are one of the categories most prone to suffer from this parasitic disease. The study was carried out in a commercial dairy farm. Feces samples of heifer calves between 2 and 8 weeks old were taken monthly for oocyst counts and Eimeria spp. identification. Of the 862 feces samples analyzed, 48% presented oocysts. When grouping the results of monthly samplings of each age group, it was observed that this percentage increased in the group of calves between 20 and 40 days of life, reaching the peak average of 85% of infection prevalence in the group with between 26 and 30 days of age. The discharge of oocysts observed between 21 and 35 days of age was superior to the rest (p<0.05). This trend appeared every month throughout the whole year. However, during March, April, June, September and November, the curves in the group categories were higher than in the remaining months (p<0.05). Twelve Eimeria species were identified, being E. ellipsoidalis, E. bovis, E. zuernii and E. auburnensis those in highest numbers. E. ellipsoidalis had an important predominance in the opg composition, >75% up to 25 days of life (p<0.05). E. bovis reached peak values in the 26 and 30 days group (p<0.05), remaining without significant variations in the last stage of the artificial milk feeding period (approximately 60 days of life), when the oocyst counts were significantly low. Oocysts of E. auburnensis appeared in great proportion (46%) in the cultures later than the previous species (p<0.05), in calves of the age groups of between 46 and 50 days of age. Oocysts of E. zuernii showed no trend associated with age. The highest prevalence of infection and of oocyst values appeared during the periods with better environmental conditions for sporulation, survival and dispersion of oocysts (spring and autumn), coincident with the highest birth rates and an elevated number of calves in the paddock. Calves developed a process of natural "vaccination" against coccidiosis. This was demonstrated by the decrease in the quantity of animals shedding oocysts and in the number of oocysts eliminated at the end of the artificial milk feeding period.     

Eimeria infections in cows in the periparturient phase and their calves: oocyst excretion and levels of specific serum and colostrum antibodies.

Faecal Eimeria oocyst excretion and levels of antibodies to first generation merozoite antigen of E. bovis in sera and colostra were followed in 86 and 70 cow-calf pairs in northern (group EF) and central Germany (group H), respectively, over periods of 3 weeks before to 3 weeks after calving in cows and from birth to an age of 63 days in calves. Oocysts were found in 30 and 7.7% of cows in groups EF and H, respectively. They belonged to 10 (group EF) and four Eimeria spp. (group H) with E. bovis, E. ellipsoidalis, E. auburnensis and E. zuerni as the most frequently occurring species. Prevalence and intensity of oocyst excretion varied with time resulting in peak values around the date of parturition, particularly in the case of E. bovis. Peak values at the time of parturition were also seen in case of strongyle egg excretion. Seven (group H) and nine Eimeria spp. (group EF) were found in the calves. The predominant species E. ellipsoidalis, E. zuerni, E. bovis and E. auburnensis were detected for the first time earlier after birth (3-5 weeks) than the others. The prevalence of Eimeria infections increased to 67.1% (group EF) and 50.1% (group H) 9 weeks after birth. Specific IgM and IgA antibody levels (the latter only determined in group EF) in cow sera remained almost constant throughout the observation period, whereas IgG(1) and IgG(2) levels were reduced at the time of parturition. Levels of specific antibodies in sera and colostra were significantly correlated. Except IgM antibodies, significant inverse correlations were found in cows between intensity of infection with E. bovis and specific serum IgG (group H) and IgG(2) (group EF) antibodies. Antibodies to E. bovis were detected in calves sera only after colostrum intake with significant correlations between levels in calves sera and colostra. Levels decreased, starting within the first week of life (most conspicuously in case of IgM and IgA) until the third week. Subsequently, but except IgG(1) antibody concentrations increased until the end of the observation period. Interrelations between antibody levels and the total amount of E. bovis oocysts excreted by the calves until the ninth week of life varied with the age of the animals. Inverse relationships in the first 3 weeks of life as suggested by negative correlation coefficients could not be proven statistically. Thus, there is no unambiguous proof for immunoprotection of calves against E. bovis via maternal immunity. Considering antibody levels in the 3-9 weeks old calves significant direct correlations with E. bovis oocyst excretion were found in case of IgM, IgG(2) and IgA, reflecting an active immune response of young calves to coccidial infection.     

Sequential in vivo measurements of body composition of calves exposed to natural infection with gastrointestinal nematodes

Sequential in vivo measurements of total body water, exchangeable sodium and exchangeable potassium, made by radioisotopic dilution techniques, were used to determine changes in body composition in calves exposed to natural infections with gastrointestinal nematodes during their first grazing season. Two groups of calves were studied, one of which received a sustained release anthelmintic bolus at turn out. Over the grazing season the bolus-treated calves showed a significantly improved pattern of bodyweight gain, compared with the untreated control calves. There were also significant increases in both total body water and exchangeable potassium, as a percentage of the bodyweight, in the bolus calves compared with the controls. These findings indicated that body protein as a percentage of bodyweight was increased in the bolus animals. The bolus-treated calves also had significantly lower serum pepsinogen concentrations, faecal egg counts and worm burdens.     

Effect of strategic treatments with invermectin on parasitism of set-stocked calves exposed to natural trichostrongyle infection in Lithuania

The effect of strategic treatments with ivermectin in first-season calves exposed to trichostrongyle nematodes on naturally contaminated pasture was studied. Twenty first season heifer calves were divided into 2 groups, according to live weight, and on 22nd May each group was turned out onto a 1 hectare pasture. Group A (Plot A) was treated with ivermectin at weeks 3, 8 and 13 after turn out, while group B (Plot B) served as an untreated control group. The study showed that control calves exhibited increase in trichostrongyle egg counts in August, while treated calves were excreting low numbers of trichostrongyle eggs. Pasture larval counts on Plot B (control animals) were low during the first part of the grazing season, followed by a steep rise towards the end of July. In contrast, the numbers of infective larvae recovered from Plot A remained low throughout the season. Both groups showed comparable weight gains from May up to the middle of July. However, from then on, Group B (controls) had lower weight gains than ivermectin treated Group A. From the end of July onwards, most untreated calves (Group B) showed clinical signs of parasitic gastroenteritis. It can be concluded that the strategical ivermectin treatments were successful, and faecal egg counts, pepsinogen levels and herbage larval counts clearly demonstrated that this was accomplished through suppression of pasture contamination with nematode eggs and subsequent reduction of pasture infectivity.     

Use of an oxfendazole pulse release bolus in calves exposed to natural subclinical infection with gastrointestinal nematodes

During the first grazing season a group of calves treated with an oxfendazole pulse release bolus achieved a mean (+/- sem) weight gain of 140.7 (+/- 6.7) kg compared with 106.5 (+/- 5.7) kg by a group treated once with ivermectin mid-season, and 116.9 (+/- 6.9) kg by a group which received no treatment. This economic advantage was maintained during the period of winter housing. By the end of the second grazing season, during which the animals received no anthelmintic medication, they weighed on average 20 kg more than the wholly untreated group, a difference which was not statistically significant. No signs of clinical disease were observed in either the animals dosed with a pulse release bolus or the undosed control animals during the two year trial period. The treatment with the oxfendazole pulse release bolus greatly reduced the degree of pasture contamination in the first year but in the second year those animals that had been treated in the first year developed higher worm egg counts (P less than 0.001) and thus augmented the levels of pasture contamination compared with the untreated control animals. Nematodirus battus and N filicollis both produced low grade but fertile infestations in the calves.     

Control of coccidiosis in turkeys with diclazuril and monensin: effects upon performance and development of immunity to Eimeria species

The effects of diclazuril and monensin, when included in the feed of turkeys from 0 to 10 wk, upon performance and development of immunity to Eimeria species was investigated. Birds were initially inoculated with a low dose of oocysts of three species of Eimeria at 3, 5, 7, and 9 days of age in order to simulate a natural infection. Weight gain and feed intake from 0 to 6 wk of age was significantly greater in medicated birds compared with those that received no anticoccidial medication. Weight gain and feed intake from 6 to 10 wk was greater in birds that received diclazuril than in unmedicated birds. No differences in performance were evident after drug withdrawal from 10 to 16 wk. Immunity to Eimeria species developed by 10 wk in birds that received no anticoccidial medication but did not develop in those given diclazuril or monensin.     

Comparative therapeutic effect of toltrazuril, sulphadimidine and amprolium on Eimeria bovis and Eimeria zuernii given at different times following infection in buffalo calves (Bubalus bubalis)

We compared the therapeutic effect of three anticoccidial drugs (toltrazuril, sulphadimidine and amprolium) in buffalo (Bubalus bubalis) calves experimentally infected with Eimeria bovis (E. bovis) and E. zuernii oocysts (3 x 104oocyst/calf). Buffalo calves (1.5-4 month old, 70-kg body weight) were randomly allocated into 3 groups (9 calves each). Group T was experimentally infected with oocysts and treated with toltrazuril (20 mg/kg BW twice orally at a 1-week interval). Group S was experimentally infected with oocysts and treated with sulphadimidine (125 mg/kg injected IM followed by half dose for 4 successive days). Group A was experimentally infected with oocysts and treated with amprolium (50 mg/kg orally for 7 successive days). Each group had three subgroups (three calves/subgroup) to represent timing of the drug administration: 1st day of coccidia infection (FD), onset of clinical signs of coccidiosis (CC), and onset of oocyst shedding into the faeces (OS). Clinical signs, body-weight gain (BWG) and number of oocysts per gram feces (OPG) were monitored daily for 35 days post-infection (DPI). The OPG were reduced (but the BWG was not different) in the T calves compared to S and A calves. Within the same group, treatment from the 1st day of infection reduced the OPG and increased the BWG compared to the later treatment timings.     

Experimental and natural infection of calves with Bunostomum phlebotomum

An experiment was conducted to determine the efficiency of a method of experimental infection of weaner beef calves with Bunostomum phlebotomum and to compare such infection with that established by natural infection. Six calves, maintained on a concrete-floored pen, were inoculated with B. phlebotomum L3 by placing the larval inocuulum, in small volume, in the outer chamber of the ear while the animal was restrained for 18 min. Inoculation doses of 20, 30, 40, 50, 60, and 80 thousand L3 were used. Six other calves were grazed on pasture known to be heavily contaminated with hookworm. All animals were killed 72 days after experimental infection and 93 days after initial exposure to pasture infection. The experimental and naturally-infected calves became patent at 55 and 66 days, respectively, after exposure to L3. Red blood cell counts and hemoglobin values were markedly depressed in both groups and lowest values coincided with onset of patency. There was difference in liveweight changes, but both groups lost weight during the prepatent period of infection and gained weight with the onset of patency. The largest number of hookworms was established at the 30000 L3 inoculation level; little or no establishment was observed at the 2 highest levels. Sizeable adult hookworm burdens were established in 4 out of 6 pastured calves. Intestinal pathology was generally more severe in experimentally-infected calves, consisting of a thickened mucosa and masses of punctate, hemorrhagic foci. Pastured calves also acquired large burdens of Ostertagia ostertagi, particularly inhibited early fourth-stage larvae. Moderate to severe abomasal pathology and elevated plasma pepsinogen were associated with ostertagiasis in the pastured calves. The experimental infection method is efficient in establishing high levels of B. phlebotomum infection in calves currently or previously infected with other gastrointestinal nematodes.     

地克珠利防控湖羊自然感染球虫用药程序及效果研究

为探讨地克珠利防控湖羊自然感染球虫的用药技术和效果,90只经粪检确诊为自然感染球虫的50日龄湖羊随机分为8组,其中第1～7组为药物试验组,分别按设计用药程序给予地克珠利,第8组为不用药对照组;应用饱和盐水漂浮法检查用药前后供试羊粪样中球虫卵囊,麦克马斯特法计数每克粪便中的卵囊数,收集阳性样品中球虫卵囊进行培养和鉴定,依用药后不同时期的球虫卵囊减少率、转阴率、平均增重率等判定药物防控球虫效果和增重效益。结果显示:按1 mg·kg~(-1)剂量给予地克珠利,每天1次,连用2 d且间隔14 d再次用药对50日龄湖羊自然感染球虫的防控效果最好;用药后第56天,共4次给予地克珠利的试验羊比对照组羊平均每只多增重2.51 kg,经济效益显著;球虫种类鉴定表明,地克珠利抗小型艾美尔球虫(Eimeria parva)、类绵羊艾美尔球虫(E.ovinoidalis)、阿撒他艾美尔球虫(E.ahsata)、槌形艾美尔球虫(E.crandallis)、颗粒艾美尔球虫(E.granulose)、斑点艾美尔球虫(E.punctata)、苍白艾美尔球虫(E.pallida)、温布里吉艾美尔球虫(E.weybridgensis)的效果良好。本研究结果为羔羊和育肥肉羊球虫病防控提供了技术方法。     

不同锰元素含量日粮对犊牛生长性能和粪尿排泄指标的影响研究

日粮1%预混料减少120mg/kg锰元素时,30天犊牛累积生长显著高于对照组（P < 0.05）,说明锰元素与犊牛的生长性能确有明显影响;但是日粮中不同的锰元素对于犊牛体尺指标均没有显著影响（P > 0.05）,说明微量元素锰对于犊牛体尺性能影响不大。而且,研究发现日粮1%预混料减少60mg/kg、120mg/kg和240mg/kg锰元素均可以适当提高犊牛粪便氮磷的表观消化率,降低犊牛多种元素的排放,其中日粮1%预混料减少240mg/kg锰元素时的氮磷消化率最高,而且可以有效降低犊牛粪氮、粪铜和粪锌的排放量、30天的尿氮排放量,效果最好。     

Field testing of a fenbendazole treatment combined with hygienic and management measures against a natural Giardia infection in calves

The need of a combination of animal treatment and environmental measures against a natural Giardia infection in calves between the age of 1 and 6 months was emphasized and evaluated. Ten commercial farms with a total of 94 calves suffering from chronic diarrhea, ill thriving and impaired growth, were included in two subsequent studies. The first study indicated that treatment of all animals with fenbendazole at 15 mg/kg during 3 consecutive days combined with environmental measures on the final day of treatment, which were either removal of bedding, thorough cleaning and ammonia 10% disinfection or relocation of the treated animals to a Giardia free environment, resulted in a total reduction in cyst excretion for at least 2 weeks. In the second study, the immunofluorescence assay (Merifluor Cryptosporidium/Giardia; Meridian Diagnostics Inc., Cincinnati, Ohio) was used quantitatively and confirmed that the combination of treatment and environmental measures resulted in a total reduction of cyst excretion during 2 weeks and in a significant (P<0.05; >or=98.0%) reduction of the cyst excretion until at least 4 weeks after treatment. Furthermore, there was a noticeable improvement of the clinical symptoms in all animals towards day 28 after treatment and 4 months after treatment health in all calves was normal.     

The effect of dietary polyunsaturated fatty acids (PUFA) on infection with the nematodes Ostertagia ostertagi and Cooperia oncophora in calves

Diet-induced changes in the polyunsaturated fatty acid (PUFA) content of immune cells influences the immune phenotype that develops following infection. The aim of this study was to examine the effect of manipulating dietary PUFA supply on tissue fatty acids composition and immunity to a mixed infection with an abomasal and an intestinal nematode parasite in calves. Calves (n=24) were allocated into two treatment groups and fed 25 g/day of either fish oil (n-3 group) or a binary mixture of palm/rapeseed oil (normal group) as a supplement in milk replacer. Within each treatment group eight calves were infected with 2000 L3 Ostertagia ostertagi and Cooperia oncophora, three times per week for 8 weeks, the remaining calves were pair-fed uninfected controls. Faecal egg counts (FEC) were carried out twice weekly. At slaughter, the whole gut was removed intact for worm counts and tissue samples were taken for fatty acid analysis. Samples of abomasum, duodenum and mid-gut were also collected for immunohistological analysis. FEC were not significantly influenced by oil supplement but tended to remain higher in the palm/rapeseed oil-fed group (normal infected). The number of intestinal immature worms was significantly (p<0.05) higher in the n-3 group. Mucosal mast cell (MMC) and eosinophil numbers were significantly increased (p<0.05) by infection and were significantly lower (p<0.05) in the intestinal tissue of the fish oil supplemented and infected group (n-3 infected group). These results suggest that feeding an n-3 PUFA-rich supplement (fish oil) can influence cellular mediators of immunity to nematode infection. This is the first report of the establishment of patency and the subsequent development of immunity to a mixed infection with O. ostertagi and C. oncophora in calves undergoing early rumen development. The trend in the FEC, MMC and eosinophil numbers in the n-3 group suggests that decreasing the dietary n-6/n-3 PUFA ratio may be a worthwhile immunonutritional strategy for potentiating the immune response to nematode parasite infection in the calf.     

Effect of social environment and oocyst dose on resistance and immunity to Eimeria tenella challenge

Chickens were exposed to graded doses of a suspension of Eimeria tenella oocysts while in environments of high (HSS) or low (LSS) social stress. Both primary cellular resistance and the sensitization phase of cell-mediated immunity were higher in the HSS environment than in the LSS environment. The manifestation of cell-mediated immunity seems to be inhibited by social stress.