首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献，搜索用时 15 毫秒
1.
The efficacy of halofuginone lactate in the prevention of cryptosporidiosis in suckling calves was evaluated in a multicentre, control versus placebo, randomised, double-blind clinical trial. Seventy-eight six- to 48-hour-old calves were treated daily with 120 microg/kg bodyweight of halofuginone lactate administered orally for seven consecutive days, while 80 calves received a placebo. Faecal samples were collected on the first day of dosing and four, seven, 14 and 21 days later, and Cryptosporidium parvum oocysts were counted and faecal indices for diarrhoea were determined after a clinical examination. An analysis of variance for repeated measurements showed a highly significant difference in favour of halofuginone lactate for both the oocyst counts (P=0.0002) and the faecal diarrhoea indices (P=0.0001) throughout the trial. The difference was greatest after seven days, when the mean oocyst count of the placebo group was 2.5 times and its mean faecal index was twice the mean of the halofuginone lactate group. One day after the end of the treatment the calves which received halofuginone lactate excreted 44 per cent fewer C parvum oocysts and 44 per cent fewer of them had diarrhoea. The reduction was even greater (65 per cent) when liquid diarrhoea was assessed, with 32.5 per cent of the calves in the placebo group having liquid diarrhoea compared with 11.5 per cent in the halofuginone lactate group. The treatment was well tolerated and easily administered.  相似文献   

2.
OBJECTIVE: To evaluate the effect of daily oral administration of decoquinate to neonatal calves experimentally challenged with various numbers of Cryptosporidium parvum oocysts. DESIGN: Clinical trial. ANIMALS: 75 calves. PROCEDURE: Calves were purchased from a commercial dairy during a 5-week period. Calves were housed in individual hutches and fed milk replacer with or without decoquinate (2 mg/kg [0.9 mg/lb per day]). Calves were randomly assigned to treatment and 1 of 5 challenge groups (0, 50, 100, 1000, or 10,000 C. parvum oocysts in 60 mL of saline [0.9% NaCl] solution administered p.o. on the day after arrival). Calves were maintained in the study for as long as 28 days. Calves were clinically assessed for diarrhea and dehydration. Fecal samples were submitted for oocyst enumeration 3 times each week. RESULTS: Treatment did not affect number of days to first watery feces (diarrhea), number of days to first oocyst shedding, or duration of diarrhea or oocyst shedding. Duration of oocyst shedding was significantly associated with challenge dose of oocysts administered to calves and number of days to first oocyst shedding. Duration of diarrhea and number of days to first oocyst shedding were significantly associated with week of arrival and number of days to first watery diarrhea. CONCLUSIONS AND CLINICAL RELEVANCE: Daily treatment with decoquinate at the dosage used in this study did not affect oocyst shedding or clinical signs associated with cryptosporidiosis. However, there was an indication that if the number of oocysts calves received could be reduced, then the duration of oocyst shedding and, hence, environmental loading of C. parvum oocysts could be reduced.  相似文献   

3.
Male Holstein calves were each inoculated with 350,000 sporulated oocysts of Eimeria bovis. Two calves were given decoquinate (0.5 mg/kg of body weight) continuously in dry feed for 29 days, and 2 calves each were given 0.5, 1, or 1.5 mg of decoquinate/kg on an every 2nd-or 3rd-day schedule for 29 days. Calves given decoquinate continuously did not discharge oocysts but had slightly loose feces. In general, the number of oocysts discharged increased and fecal consistency decreased as the time between feeding of medicated feed increased. Calves given 0.5 or 1.5 mg of decoquinate/kg every 3rd day discharged more oocysts and had more diarrhea than did calves given 1 mg of decoquinate/kg every 3rd day. At postinoculation day 29, calves were euthanatized. At necropsy, intestinal tissues of calves given decoquinate were mostly normal. Apparently, reduced infections along with the elapsed time were sufficient to resolve most intestinal lesions caused by the coccidia. Decoquinate was most effective when fed continuously at 0.5 mg/kg. However, when fed at 1 or 1.5 mg of decoquinate/kg every 2nd day or 1.5 mg of decoquinate/kg every 3rd day, oocyst production was reduced and clinical coccidiosis was prevented.  相似文献   

4.
Twenty-five 6-week-old Holstein male calves were each inoculated with 500,000 sporulated oocysts of Eimeria bovis. Two nontreated (control) and 3 treated calves (1.5 mg of decoquinate/kg of body weight in feed) were necropsied 7 days after inoculation. Similar groups of calves were necropsied at 12, 18, 22, and 28 days after inoculation. Treated calves were started on medicated feed 2 days before inoculation or at 7, 12, or 15 days after inoculation or were on continuous medication from the day of inoculation. Control calves were not given medication. Early schizonts were in the small intestines of control calves at 7 days after inoculation, but none was in the treated calves that were started on medicated feed 2 days before inoculation. Schizonts were present in the small intestine of both treated and control calves at 12 days after inoculation. At 18 days after inoculation, control calves had schizonts in the small intestine and gamonts and oocysts in the cecum and large intestines, but treated calves only had schizonts in the small intestine. At 22 days, control calves had schizonts in the small intestine and gamonts and oocysts in the large intestine; treated calves had schizonts in the small intestine. At 28 days, controls still had schizonts in the small intestine and gamonts and oocysts in the cecum and large intestine; the treated calves that had been on continuous medication did not have schizonts, gamonts, or oocysts in the tissues. Decoquinate apparently kills sporozoites or arrests development and release of merozoites from the schizonts when fed at 1.5 mg/kg of body weight in the feed.  相似文献   

5.
To evaluate the efficacy of halofuginone lactate (Halocur; Intervet) when used prophylactically against cryptosporidiosis in dairy calves, 513 Holstein heifer calves were randomly distributed between two experimental groups. Those in the treatment group (n=259) received 0.1 mg halofuginone base per kg bodyweight daily in a 10 ml solution, for the first seven days following birth, while those in the control group (n=254) received an equal volume of a placebo solution. Faecal samples were collected weekly from all calves until three weeks of age to test for Cryptosporidium oocysts and to assess the diarrhoeal status. Growth parameters of the calves were also recorded at approximately four months of age. Calves that received halofuginone were significantly less likely to shed Cryptosporidium oocysts during the course of the study than placebo-treated calves (odds ratio 0.6, 95 per cent confidence interval 0.4 to 0.9, P=0.009). Mean growth measurements of calves in the treated group were consistently higher than those of the control calves (hipometer-derived P=0.052, wither height P=0.097) and mortality was lower in the treated group (P=0.07). However, these differences were not statistically significant (P>0.05). No association was found between the prophylactic use of halofuginone and the incidence of calf diarrhoea.  相似文献   

6.
Two experiments were conducted to evaluate lasalocid as a coccidiostat in Holstein calves and to compare lasalocid with monensin and decoquinate. In experiment 1, calves in 3 groups (6 calves/group) were each inoculated with 500,000 sporulated oocysts, 88% of which were Eimeria bovis and 12% were E zuernii. Calves in each group were given lasalocid-medicated feed at 0.50 (group 3), 0.75 (group 4), or 1 mg/kg (group 5) of body weight/day for 45 days. Two control groups (6 calves/group) were also evaluated; calves in control group 2 were inoculated and nontreated, and calves in control group 1 were noninoculated and nontreated. At 0.50, 0.75, or 1 mg/kg/day, lasalocid was equally effective in preventing induced coccidiosis (E bovis and E zuernii) in calves. Compared with inoculated nontreated controls, treated calves had significantly (P less than 0.05) fewer oocysts in feces and had fewer clinical signs of coccidiosis from days 16 to 30 after inoculation. Experiment 2 was conducted to compare the effectiveness of monensin, lasalocid, and decoquinate for the prevention of experimentally induced coccidiosis. Calves (n = 48) were allotted into 4 groups (12 calves/group); each was inoculated orally with 275,000 sporulated oocysts, predominantly E bovis and E zuernii, and each was given nonmedicated feed (group 6) or feed medicated with 33 mg of lasalocid (group 7), decoquinate (group 8), or monensin (group 9)/kg of feed for 46 days. Calves given medicated rations had significantly (P less than 0.05) fewer oocysts in their feces and fewer clinical signs of coccidiosis than did calves given nonmedicated rations.(ABSTRACT TRUNCATED AT 250 WORDS)  相似文献   

7.
Twenty coccidia-free Holstein bull calves were allotted to groups to study effects of treatment with lasalocid and decoquinate on subsequent resistance to coccidiosis (Eimeria spp infections). Calves fed medicated rations of either drug at dosages of 50 mg/kg of feed (approx 1.2 mg/kg of body weight) had significantly fewer oocysts (P less than 0.01) than did nontreated controls regardless of other procedures used. Treated calves premunized with 2,000 oocysts/day for 5 days and later challenge inoculated with 200,000 oocysts did not develop diarrhea, unless the drugs were withdrawn from feed. Animals premunized (2,000 oocysts/day for 5 days) in absence of drug were no more resistant to the challenge inoculation than nonpremunized animals. These results indicated that lasalocid and decoquinate were efficacious coccidiostats and protected calves as long as they were administered. Cessation of drug treatment usually resulted in appearance of oocysts in feces and diarrhea. Premunization alone cannot be expected to prevent coccidiosis when animals are exposed to large numbers of oocysts.  相似文献   

8.
Prevalence and control of bovine cryptosporidiosis in German dairy herds   总被引：6，自引：0，他引：6  
In a 5-year survey regarding its prevalence and importance in five German state veterinary laboratories Cryptosporidium was diagnosed annually in 19-36% of faecal samples either submitted to the laboratories or taken post mortem. In approximately half of the cases no other enteropathogens were detected. However, only 73% of 30 laboratories participating in a questionnaire survey routinely tested for this parasite, and the majority of researchers considered cryptosporidiosis to be of minor importance. In a placebo-controlled field study 152 suckling calves were treated daily against cryptosporidiosis either with sulfadimidine or with halofuginone (Halocur, Intervet) over 1 week. Treatment by oral drench started at the onset of diarrhoea in the herd. Oocyst excretion, faecal consistency and health status were recorded five times for a 3-week period. Oocyst excretion peaked 7-14 days in the placebo group after the onset of diarrhoea, and during that period prevalence and intensity of excretion were significantly lower in the halofuginone-treated group compared to the sulfadimidine and the placebo control groups. The health status (diarrhoea, dehydration) declined in all groups but was significantly (P<0.05-0.001) better in the halofuginone group in the first 2 weeks. Halofuginone effectively (P<0.05-0.001) reduced oocyst excretion and improved the health status of the treated animals, while sulfadimidine had no effect against Cryptosporidium.  相似文献   

9.
This study was carried out to find the importance of Cryptosporidium parvum in diarrhoea of neonatal calves in two types of breeding - suckling and dairy calves - in France. Different agents causing neonatal diarrhoea, E. coli, rotavirus, coronavirus, Salmonella and Cryptosporidium were systematically researched in faeces. 1. Suckling calves: In 40 livestock farms selected for diarrhoea, 311 calves 4 to 10 days old which had diarrhoea for less than 24h or no diarrhoea, were included in the study. A prophylaxis of neonatal diarrhoea had been carried out in 21 of the 40 livestock farms. On D0 (inclusion day), the mean age was 6 days, 82% presented a good initial general condition and 76.2% had a good appetite; 48.6% were diarrhoeic but 91.3% presented no sign of dehydration. Only 6.1% were infected by E. coli K99, 14.3% by rotavirus, 6.8% by coronavirus, 0.3% by Salmonella but 50% excreted C. parvum oocysts. This later percentage increases up to 84% and 86% by D3 and D7, respectively . We note that 16% of the 4-day-old calves on D0 are excreting oocysts and this percentage increases as a function of the age of the calf on D0 to reach 90% to 95% by the age of 8 days. 10 out of 12 dead calves excreted C. parvum oocysts. From D0 to D14 the other pathogen agents show a relative or a decreasing stability. 2. Dairy calves: 382 calves which had diarrhoea for less than 24 h or no diarrhoea, aged 8 to 15 days coming from six industrial livestock farms were included in the study. On D0, 99% of the calves presented a good initial general condition, 99.7% had a good appetite and no calf was dehydrated. At this date (D0), 16.8% of the calves excreted cryptosporidia. This percentage increases up to 23% and 51.8% on D3 and D8, respectively, then decreases to 31.9% on D14. The pressure of the other pathogenicagents remains relatively stable, excepted for rotavirus on D7 (from 9.9% on D0 to 27.2% on D7, then 12.6% on D14) which does not explain the concomitantpeak in diarrhoea because the infection by rotavirus on D7 is more frequent in non-diarrhoeic calves than in diarrhoeic calves. Our results show that Cryptosporidium prevalence is higher in suckling than in dairy calves and C. parvum constitutes actually in both cases the major aetiological agent of neonatal diarrhoea.  相似文献   

10.
Taylor, M. A., Bartram, D. J. The history of decoquinate in the control of coccidial infections in ruminants. J. vet. Pharmacol. Therap.  35 , 417–427. Decoquinate is a quinolone derivative that has been used for over 20 years in the control of coccidiosis in domestic ruminants. Decoquinate treats coccidiosis in lambs and calves and prevents coccidiosis in lambs when administered in feed at a dosage of 1 mg decoquinate/kg bodyweight (b.w.) daily for at least 28 days. It prevents coccidiosis in calves and aids in the prevention of coccidiosis in lambs when administered in calf and ewe feed, respectively, at a dosage of 0.5 mg/kg b.w. daily for at least 28 days. Decoquinate also aids in the prevention of abortions and perinatal losses owing to toxoplasmosis by medication of ewe feed at a dosage of 2 mg/kg b.w. daily, fed continuously for 14 weeks prior to lambing. Several field studies have reported reductions in cryptosporidial oocyst shedding. Decoquinate acts early in the life cycle of Eimeria on sporozoites, released from ingested oocysts, and on first‐generation meronts, arresting development and release of merozoites and thus preventing further damage to the intestines owing to the gametocyte stages. Production benefits associated with the use of decoquinate are due mainly to its action as a coccidiostat rather than any effects on diet utilization or ruminal fermentation.  相似文献   

11.
Sixteen 7-week-old Holstein male calves were inoculated with sporulated oocysts of Eimeria zuernii. Four calves (controls) were euthanatized and necropsied at 14 and 20 days after inoculation (DAI). Two calves were treated with 20 mg of dexamethasone (IM) on 13, 14, and 15 DAI and euthanatized and necropsied 17 DAI and 2 calves were given similar treatments and necropsied 20 DAI. The 8 other calves were euthanatized and necropsied 20 DAI. Two were started on the anticoccidial drug decoquinate in feed 13 DAI; 2 others were given decoquinate on the same schedule plus dexamethasone on 13,14, and 15 DAI. Two calves were given the antibiotic narasin in feed beginning 13 DAI and 2 calves were given parasin on the same schedule plus dexamethasone on 13,14, and 15 DAI. All calves, except 2 controls necropsied 14 DAI and 4 calves given decoquinate, discharged moderate-to-large numbers of oocysts in feces and had moderate-to-serve changes in fecal consistency. Histologic examinations revealed large numbers of endogenous stages in tissues of calves treated or not treated with dexamethasone. Few endogenous stages were observed in tissues from calves that were given decoquinate or decoquinate plus dexamethasone. Calves given narasin or narasin plus dexamethasone had moderate-to-large numbers of endogenous stages in the tissues.  相似文献   

12.
Cryptosporidium parvum infection and the pattern of oocyst shedding were observed in calves. A total of 480 fecal samples were collected from 30 calves (age, < or =30 days) over a period of 10 months from June 1998 to March 1999. A sucrose centrifugal flotation technique revealed 28/30 (93%) calves were passing Cryptosporidium oocysts. Oocyst shedding was first detected on the sixth day after birth, with 8% of the calves testing positive. This rate increased day by day and reached approximately 80% by day 15. Oocyst shedding varied from 1 to 13 days, with a mean of 7 days. Calves infected with C. parvum had a significantly higher rate of diarrhea (33%) than non-infected calves (8%) (P<0.05), suggesting C. parvum infection as the likely cause. The mean number of oocysts excreted by calves < or =30 days old was approximately 6x10(7) per gram of feces. These results indicated that one calf would excrete some 6x10(11) oocysts in the first month after birth, taking both the quantity of feces in a day and the period of excretion into consideration. Accordingly, it is clear that calves are important in the spread of cryptosporidiosis to calves and humans.  相似文献   

13.
Effects of lasalocid on coccidial infection and on calf growth were examined in 16 Holstein bull calves. Calves were assigned randomly to a 2 x 2 factorial arrangement of starter ration containing 0 or 40 mg of lasalocid/kg of starter, beginning when calves were 3 days old (SE = 0.046), and single oral inoculation with 0 or 30,000 sporulated oocysts (Eimeria bovis) at 28 days. Pelleted calf starter was fed ad libitum from day 1; milk replacer was fed at a rate of 3.6 kg/d until day 28. Mean daily gain, dry-matter intake, and body weight were increased in calves fed lasalocid and decreased in those inoculated with coccidia. Addition of lasalocid to the feed improved gains by 8% in uninoculated calves and by 50% in inoculated calves. Fecal oocyst numbers were reduced when lasalocid was fed to inoculated calves. Feces were more abnormal in calves inoculated with coccidia. Respiration rates, rectal temperatures, PCV, and serum sodium and potassium concentrations were unaffected by treatment. On the basis of findings in this study, lasalocid minimized effects of coccidial challenge inoculation and increased growth of calves.  相似文献   

14.
The aims of the present study were to investigate the excretion of Eimeria alabamensis oocysts by young cattle during their first grazing season and during the first 16 days of their second grazing period. In trial 1, nine first-season grazing heifers were studied and found to have become infected with E. alabamensis shortly after turnout. The next grazing period they were turned out on to a permanent pasture together with two first-season grazing calves. Faecal samples were collected before turnout and then daily from day 3 to day 16. The second-season grazing heifers excreted insignificant numbers of E. alabamensis oocysts, whereas one of the two first-season grazing calves excreted up to 703,000 oocysts/g of faeces (OPG), indicating that the pasture was contaminated. In trial 2, faecal samples were collected from 12 calves before their first turnout in May, daily from day 2 to day 20 after turnout and then once a week until the end of September. The calves grazed pastures used in previous years by first-season grazing calves. Nine of the calves developed clinical E. alabamensis coccidiosis 4-7 days after turnout and excreted more than 950,000 OPG on days 9-10. By day 17 the oocyst excretion had decreased below 900 OPG and remained low throughout the rest of the grazing season. The results of the two studies indicate that reinfections with E. alabamensis are of little clinical importance in calves grazing contaminated pastures, and that young stock infected with E. alabamensis during their first grazing season may be used to cleanse contaminated pastures without risk of developing clinical coccidiosis.  相似文献   

15.
SUMMARY Thirty-six, 2- to 4-day-old Friesian bull calves were divided into 4 groups and fed milk replacer and calf starter pellets ad libitum in separate pens. Four treatments were applied; lasalocid in milk (1 mg/kg body weight/day) (M), lasalocid in starter (F), lasalocid in both milk and starter (M+F) and untreated (C). When the calves were about 2 weeks old they were each dosed orally with 550 000 sporulated Eimeria sp oocysts, mainly E zurneii and E bovis. The infection, detected by faecal excretion of oocysts, was suppressed in the M+F and M groups. There was significant excretion of oocysts in the F group but these calves did not show any clinical signs of coccidiosis. Untreated calves were affected with diarrhoea containing blood on the 24th day after inoculation. Body weight gain and intake of starter pellets was also depressed in the untreated calves during the time they were clinically affected. It is concluded that mixing lasalocid in milk replacer (or fresh milk) is an effective method of protecting young calves against early infection with coccidia.  相似文献   

16.
This study was conducted to determine the effect of feeding high milk volumes on the growth rate, health and cross-sucking behaviour in group-fed Jersey calves. Three-day-old heifers (n = 120) in a seasonal calving dairy herd were randomly assigned to one of 6 treatment groups. Three groups received high milk volumes (HMV), consisting of ad libitum milk or milk replacer feeding twice a day, while 3 groups received restricted milk volumes (RMV), consisting of 2 l twice daily, during the pre-weaning period. After a pre-weaning period during which feeding was reduced to once daily, all calves were weaned at 42 days and monitored until 60 days of age. Adjusting for birth mass, birth date, dam parity and sire, average daily mass gain (ADG), both pre-weaning (days 0-42) and overall (days 0-60), was higher in HMV than in RMV calves (P < 0.001). After weaning, growth rates showed no differences and at 60 days of age the HMV calves maintained a 6.74 kg advantage in mean body mass (P < 0.001). The mean intake of dry starter feed was higher in RMV than in HMV calves. Overall feed conversion rate of HMV calves was 9.6 % better than RMV calves. However, the variable cost per kg mass gain was 12 % higher for HMV calves. In the RMV groups 75 % of calves showed cross-sucking behaviour pre-weaning and 18 % post-weaning, whereas in HMV calves the proportions were 2 % and 7 %, respectively. There was no significant effect of milk volume on the incidence of diarrhoea. We conclude that the feeding of high volumes of milk to Jersey calves has a positive effect on growth rate, without compromising health or reducing solid feed intake after weaning. However, the higher cost of such a feeding system may limit its implementation.  相似文献   

17.
Cryptosporidium parvum is an apicomplexan parasite that is an important cause of diarrhea in neonatal calves and humans. No treatment is currently available for neonatal calves. We have recently learned from colleagues in the pharmaceutical industry that dairy practitioners are sometimes using decoquinate for the treatment of neonatal bovine cryptosporidiosis. Therefore, the present study was undertaken to determine whether the clinical observations in calves can be substantiated by laboratory investigation. Oocysts of the KSU-1 isolate of C. parvum were used to infect human ileocecal epithelial cells in vitro to measure the efficacy of treatment using an ELISA based assay. No activity was observed at 10 or 50microM decoquinate, but at 100microM an 8% inhibition of development was seen. Oocysts of the AUCp-1 isolate of C. parvum were then used to infect suckling mice. The numbers of oocysts observed in suckling mice treated with 2.5 or 5.0mg/kg decoquinate were not significantly different from untreated control suckling mice (p0.05). The results of our study suggest that decoquinate should have little efficacy for treatment of neonatal bovine cryptosporidiosis if administered once per day and that any clinical improvement observed in treated calves may be due to factors unrelated to decoquinate's effect on C. parvum.  相似文献   

18.
Eighteen female Holstein calves, raised as natural herd additions under conditions typical of a well-managed midwestern United States dairy farm, were used in a natural-exposure study to determine the anticoccidial efficacies of lasalocid and decoquinate. Calves were allotted to 6 treatment blocks of 3 calves each as they were weaned. Within each block, calves were randomly assigned to be given either lasalocid or decoquinate or to remain as a nonmedicated control. Calves were given medication for 90 days and remained separated from other calves for 120 days. Adjusted weight gains were consistently greater in calves that were given medication; however, differences were not statistically significant. Fecal specimens were obtained from calves at weekly intervals during the study. Overall, oocyst shedding was low. During the medication period, quantitative mean fecal shedding of oocysts was reduced eightfold in calves given decoquinate and four-fold in calves given lasalocid, as compared with nonmedicated control calves. During the period following the medication period, calves that had been controls shed fewer oocysts than did calves that had previously been given medication. A pairwise comparison of the proportion of specimens that were oocyst-positive was made to assess qualitative oocyst shedding among treatment groups. During the medication period, qualitative oocyst shedding (all species, Eimeria bovis, E zuernii, species other than E bovis and E zuernii) was greater in controls than in either lasalocid-or decoquinate-treated groups. Like-wise, lasalocid-medicated calves shed oocysts more frequently than did the decoquinate-medicated group. After medication, qualitative findings were reversed. Little diarrhea was noticed in treatment or control calves during the study.(ABSTRACT TRUNCATED AT 250 WORDS)  相似文献   

19.
Preruminant calves excreted coccidia oocysts in their faeces after 3 weeks of group housing. Two weeks of oral sulphadimidine (SDM) administration, 50 mg/kg on the first day of treatment followed by daily administration of 37.5 mg/kg, under the same housing conditions kept the faeces free of oocysts. Three weeks later, these calves excreted oocysts again. Repetition of the same treatment for 2 weeks controlled the infection again, but a second treatment for 5 days did not suffice. The repeated long treatment affected immunoglobulin levels adversely. SDM given repeatedly at a lower dose rate (30 mg/kg) for 1-week periods with medication-free intervals of 1 week controlled the infection and no adverse effects were noted. In comparison with controls, weight gains were greater in treated calves.  相似文献   

20.
The numbers of Eimeria oocysts per gram (opg) and the dry matter content of 449 faecal samples taken from 54 calves in 8 herds in south west Sweden were determined during the last 2 weeks before and the first 3 weeks after the animals were turned out to pasture. While they were housed only between 0 and 580 opg were found and in 2 of the herds the numbers of oocysts remained low after turn-out. In the other 6 herds the numbers of oocysts increased after 8 to 10 days and reached a peak of between 1080 and 80 803 opg 9 to 18 days after turnout. By 21 to 24 days after turn-out the opg-values had declined to their initial levels. Eimeria alabamensis accounted for most of the increase, but small numbers of oocysts of E. auburnensis, E. bovis, E. bukidnonensis, E. cylindrica, E. ellipsoidalis, E. pellita, E. subspherica, E. wyomingensis and E. zuernii were also observed. The interval between turn-out and the start of the increase in excretion of oocysts corresponded closely to the prepatent period of E. alabamensis and overwintered oocysts were therefore the most likely source of the infection. In 6 of the herds the dry matter content of the faeces of the calves decreased after turn-out and 56 % of the calves had clinical diarrhoea. Although it cannot be excluded that change of diet may have contributed to these symptoms, E. alabamensis infection is suggested as a potential cause of diarrhoea and loss of condition in calves in Sweden during their first weeks on pasture.  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号