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1.
Grazing herbivores avoid grass swards contaminated with faeces as the ingestion of faeces is a common route of micro- and macro-parasite transmission. The recent novel finding that herbivores do not avoid grass swards contaminated with rabbit faeces suggests that disease risk posed to herbivores by rabbits is determined by rabbit ranging and excretory behaviour. Using as a case study rabbits and the risk Mycobacterium avium sub-species paratuberculosis (M. a. paratuberculosis) poses to cattle, the interaction between rabbits and grazing pasture was studied on an infected farm in the east of Scotland in spring and autumn 2000. Radio telemetry, burrow surveys and faecal pellet count data were collected on two areas (Areas 1 and 2) of the farm with different habitat mosaics, to study the potential effects of season and habitat on the spatial distribution of rabbits faeces and thus disease in the environment. Twenty one rabbits were radio tracked and a total of 902 fixes collected. Mean home range sizes (100% minimum convex polygons) were between 2.0 and 7.1 ha per rabbit per season. Home ranges were significantly larger in spring, and in Area 1 which had more moor and woodland and less rough pasture. Rabbits used rough pasture most in Area 1 and gorse scrub in Area 2. In both areas, significantly more burrows were located in gorse scrub than in any other habitat. Most faecal pellets were deposited on the moorland habitat of Area 2 in autumn. In habitats to which grazing livestock had access, the mean rate of faecal deposition was 8571 pellets per ha per day. The greatest risk of disease transmission occurred in habitats of poor grazing quality (e.g., gorse scrub) which were used by rabbits for burrowing and thus contained high concentrations of faeces. The findings of the study are discussed in relation to management practices aimed at reducing disease risk to livestock, including the fencing of scrub and the reduction of rabbit population size to prevent expansion of rabbit burrows from scrub into grazing pastures.  相似文献   

2.
Despite the large body of circumstantial evidence to suggest a link, the means by which bovine tuberculosis is passed from badgers to cattle remains unclear; pasture contamination with the urine, faeces and/or sputum of infectious badgers is believed to be the main route of transmission. Therefore the behaviour of grazing cattle was studied to determine whether they avoided investigating and/or grazing pasture contaminated with badger excreta, and whether different farm management practices enhanced the potential for disease transmission. Active latrines were avoided by most cattle until the sward length in the rest of the field was reduced, after which there was an increasing likelihood that active badger latrines would be grazed. Most of the cattle grazed active badger latrines, but cattle of low rank within the herd grazed latrines more heavily. Farm management practices that reduced the availability of long swards shortened the period of investigative behaviour and greatly enhanced the risk that cattle would graze active badger latrines. Cattle were more likely to graze pasture away from latrines that was contaminated either with badger urine or single faeces. Because bacilli remain viable in the soil for up to 2 years, there is the potential for bacilli to accumulate at active badger latrines, and these could pose a significant risk to cattle, even when the latrine is no longer being used by badgers. Cattle readily grazed the lush sward at disused latrines, during which they could ingest contaminated soil; the amount of soil ingested increases as sward length decreases.  相似文献   

3.
In grazing systems, heterogeneous distributions of forage resources and faeces result in localised accumulations of nutrients and parasites (both macroparasites and microparasites), creating trade-offs between the costs of exposure to infestation or infection and the benefits of nutrient intake. Each contact between livestock and faeces in the environment is a potential parasite/pathogen transmission event. Thus, herbivores must make foraging decisions in complex environments which will affect their intake of both nutrients and parasites. However, the pattern of forage and faecal resources in agricultural environments will also be affected by the grazing management system in place. The aim of this study was to investigate the effect of grazing management on the risk of infection/infestation to livestock. We used a spatially explicit individual based stochastic foraging model to simulate livestock contact (both grazing and investigative) with faeces in the environment. The model was parameterised to simulate cattle grazing under three types of grazing management: set stock (i.e. where sward growth and cattle intake are in equilibrium in a single field); a two pasture rotation grazing system with increasing number of rotations; and a rotational grazing system with two rotations and increasing subdivisions of the pasture. Overall the amount of cattle contact with faecal-contaminated patches was similar in both set stocking and rotational grazing scenarios, suggesting no difference in the risk of infection or infestation between the different systems. However, the timing and absolute amounts of peak contact varied greatly indicating that different grazing management systems expose livestock to risks of different types of parasites at different times of the grazing season. Intensive rotational systems with small pasture blocks (especially the first grazing period) maximised livestock contact with fresh faeces, and thus exposure to microparasites (e.g. bacterial pathogens). Livestock re-entering pasture blocks in rotational systems and set stocked livestock had the highest contact with old faeces and thus have a greater risk of macroparasite transmission (gastrointestinal nematodes). This study highlights how livestock management affects the highly dynamic interaction between livestock and distributions of parasites in the environment and thus the levels of livestock exposure to parasites and pathogens via the faecal–oral route.  相似文献   

4.
This study was carried out to examine the survival of infective Ostertagia ostertagi larvae (L(3)) on pasture under different simulated conditions of grazing, i.e. mixed grazing of cattle and nose-ringed sows, or grazing by cattle alone. Standardised pats of cattle faeces containing O. ostertagi eggs were deposited on three types of herbage plots, which were divided into zone 1: faecal pat; zone 2: a circle extending 25cm from the edge of the faecal pat; zone 3: a circle extending 25cm from the edge of zone 2. For "tall herbage" (TH) plots, the herbage in zone 2 was allowed to grow naturally, while the herbage in zone 3 was cut down to 5-7cm fortnightly, imitating a cattle-only pasture. For "short herbage" (SH) plots, the herbage in both zones 2 and 3 were cut down to 5-7cm fortnightly, imitating mixed grazing of cattle and sows. The grass in the "short herbage and scattered faeces" (SH/SF) plots were cut as for SH plots, and the faeces were broken down 3 weeks after deposition and scattered within zone 2, imitating the rooting behaviour of co-grazing sows. Five faecal pats from each plot group were collected on monthly basis, along with the herbage from zones 2 and 3 cut down to the ground. Infective larvae were then recovered from both faeces and herbage. The numbers of L(3) recovered from zone 1 were higher in the TH plots than in the other two groups and, furthermore, the larval counts from SH plots were always higher than from SH/SF plots. The three groups followed a similar pattern during the season regarding numbers of L(3) in zone 2, and no clear patterns between plot types were obtained. The presence of L(3) in zone 3 was almost negligible. Important differences were seen throughout the study from the biological point of view; more L(3) were able to survive in faeces on the TH plots, presumably reflecting a better protection from heat and desiccation compared to those in the other plots. The overall results support the idea that mixed grazing of cattle and pigs favour the reduction of O. ostertagi larval levels in pasture. This reduction is mainly due to the grazing behaviour of pigs, which by grazing up to the very edge of the cattle faeces, will either expose the larvae in faeces to adverse environmental summer conditions or ingest cattle parasite larvae, or both.  相似文献   

5.
The detection of Mycobacterium paratuberculosis organisms in bovine faeces by isolation was compared with that by the microscopical examination of Ziehl-Neelsen stained faecal smears for the presence of clumps of acid-fast M. paratuberculosis organisms. Faeces were obtained from cattle naturally or experimentally infected with M. paratuberculosis as well as from uninfected cattle. Microscopical examination was an unreliable method for the detection of M. paratuberculosis organisms, since the organisms were only detected in 99 (=55.9%) of 177 culturally positive faecal samples. 1111 addition, clumps of acid-fast organisms indistinguishable from M. paratuberculosis were also observed iin three of 18 samples from cattle free from Johne's disease and in 18 of 37 culturally negative samples from paratuberculous cattle. When M. paratuberculosis organisms were added to faeces from an uninfected cow, results showed that isolation attempts should be positive when 15 or more M. paratuberculosis organisms per gram of faeces are present.  相似文献   

6.
Paratuberculosis (PTB) in Brazil has previously only been reported in imported animals and is officially considered as an exotic disease. A dairy herd, which had no imported animals, presented clinically suspect animals and was investigated for paratuberculosis using faecal culture, histopathology, indirect ELISA and the agar gel immunodiffusion test. Infection with Mycobacterium avium subsp. paratuberculosis (Map) was confirmed by culture of faeces from five cows with clinical symptoms of PTB and in 7/24 randomly selected asymptomatic cows from the same herd. Two cows with clinical symptoms were necropsied and their tissues were positive for Map by culture and histopathology. Twelve asymptomatic, randomly selected cows were positive on ELISA. The results confirmed the presence of PTB in this dairy herd and for the first time demonstrated the disease in a herd of native-bred cattle in Brazil.  相似文献   

7.
An experiment to determine the origin of populations of infective larvae of cattle nematode parasites on pasture during winter was conducted in south-west Western Australia. Six pasture plots were contaminated with worm eggs by grazing worm-infected cattle for periods of a month during summer and autumn. Each plot was contaminated at a different time from the rest. The levels of infective larvae were determined by counting the worm burdens of tracer calves which test-grazed the plots the following winter.Tracer calves which grazed the plots contaminated during summer acquired few worms, whereas those that grazed the plots contaminated during autumn acquired many worms. It was concluded that the hot, dry conditions prevailing during summer and early autumn prevented the development of eggs or survival of larvae in dung pats or free on pasture. In this environment, a programme of worm control which relied on administration of anthelmintic to grazing cattle to prevent autumn contamination of pasture would be most likely to succeed if the first treatment was given in early autumn.  相似文献   

8.
OBJECTIVE: To determine the prevalence of infection of cattle with the sheep strain of Mycobacterium avium subsp paratuberculosis at least two years after exposure at < 6 months old. DESIGN: Prospective survey One thousand seven hundred and seventy-four cattle from 12 properties (Farms A to L) were sampled by ELISA and faecal culture to detect evidence of infection with M a paratuberculosis. All properties had a known history of Johne's disease (JD) in sheep, and sampled cattle were likely to be susceptible to JD at the time they were first exposed, being at an age of 6 months or less. In addition, opportunistic investigations were undertaken of ELISA reactor cattle discovered during testing for the Australian Johne's Disease Market Assurance Program for Cattle (Farms M and N). RESULTS: All animals in the survey gave negative results on serology while one animal from a herd of 349 gave a positive faecal culture result. Follow-up faecal culture, post-mortem and histopathology on the latter animal were negative, suggesting that it was a passive faecal shedder or carrier. Two occurrences of OJD transmission to cattle were detected during the opportunistic investigations. CONCLUSION: These observations confirm existing beliefs about the risk of transmission of OJD to cattle, that the risk of transmission is low. However transmission occurs sporadically. An estimated upper limit of prevalence of S strain M a paratuberculosis infection in susceptible exposed cattle in the OJD high prevalence area of New South Wales is 0.8%, assuming a common prevalence within herds.  相似文献   

9.
A total of 50 sheep originating from 15 Dutch farms with a known paratuberculosis infection in their cattle herd, but with no history of paratuberculosis infection in their sheep flock, were examined for infection with Mycobacterium avium subsp. paratuberculosis (Map). The sheep had been grazing on the same pastures as the cattle or on pastures fertilised with manure from these cows. The sheep were screened for paratuberculosis by serum biochemistry, serology and intradermal skin tests. At necropsy they were examined macroscopically, microscopically and bacteriologically for paratuberculosis.From 10 sheep, originating from eight flocks, Map could be isolated from various tissues but not from the intestinal contents, after an incubation period of 2.5-4 months. Six of these culture-positive sheep had no macroscopic signs of paratuberculosis at necropsy. Seven sheep were Map culture negative but showed macroscopic and microscopic lesions consistent with a paratuberculosis infection. Results of serology and skin tests did not correlate with the results of bacteriological culture. Serum concentrations of calcium, albumin and total protein of the infected, suspected and negative sheep were not different. These results indicate that a substantial number of the sheep examined were infected with Map. Even though this bacterium was not isolated from their faeces, the possibility that these sheep could have been shedding Map with their faeces below detection level or at a later stage of the disease cannot be eliminated. Map infected sheep should, therefore, be considered as a possible factor in the epidemiology of with Map infected cattle herds in The Netherlands. At necropsy bacteriological culture of Map should be performed on a routine basis to improve the diagnosis of paratuberculosis in sheep.  相似文献   

10.
Ward CJ 《Veterinary parasitology》2006,138(3-4):268-279
A computer model of the population biology of Ostertagia ostertagi in young cattle and the effect of the parasite on animal growth has been constructed. It was validated against results from field trials where worm populations and rate of growth of cattle treated with anthelmintics were compared to similar groups of untreated animals. A close correlation between observed and predicted values for faecal egg and pasture larval counts was seen in the cattle which had been treated with an oxfendazole pulse release bolus at turnout. Timings and peak values were less accurately predicted in the untreated cattle. Although predictions for live weight gain during the grazing season indicated that the model may be overestimating the potential growth rate of cattle, it is considered that the model provides a suitable tool for comparing the effectiveness of different worming programmes under farm conditions. The computer simulation also allowed examination of the underlying influences and interactions between parasitological factors, such as numbers of immature and adult worms, and animal and pasture factors, such as sward height, grass consumption and feed conversion, in the parasite's influence on animal performance.  相似文献   

11.
During the 1997 Swedish grazing season, faeces were collected every 3 weeks on 7 occasions from young grazing cattle with moderate nematode parasite infections. From this source 12, 400 g dung pats were set up on each sampling occasion on a specially designated area of pasture. Half of these pats were placed on pasture where it was aimed to prevent snow cover during the subsequent winter. During the grazing season, herbage growth was kept at reasonably uniform height by clipping and the dung pats were protected from destruction by animals and birds. At the time of animal turn-out the following year (7th April 1998), it was observed that all dung pats had disappeared. Assessments of the survival of infective larvae, both on pasture and in soil, were made in a circular area encompassing the location of each pat. These sampling procedures were completed within a 3 week period. All faecal deposits yielded infective larvae at turn-out the following year, with proportionally greater numbers developing from nematode eggs deposited in cattle dung during the mid third of the previous grazing season. The surface layer of soil was found to be an important reservoir for infective larvae, with numbers recovered being approximately half those found in the overlying pasture samples. No significant differences were found between the normal pasture and snow excluded pasture in the number of infective larvae recovered from both pasture and soil samples. The epidemiological consequences of these findings are discussed.  相似文献   

12.
An absorbed enzyme immunoassay (EIA) test for Johne's disease in cattle was developed in which absorption of cross-reacting antibodies occurred as a rapid reaction in solution rather than overnight with whole organisms and a subsequent centrifugation step. Total test time was reduced to less than 2 h with a minimum of manipulations. The test was evaluated in cattle herds from Johne's disease-endemic and Johne's disease-free regions of Australia. Specificity was 99.8%. Calculations of sensitivity were affected by the history of the herd under test. However, the EIA detected in excess of 80% of animals before onset of clinical disease and 65% of faecal shedders were EIA positive on, or before, first detection of Mycobacterium paratuberculosis in their faeces. The test should aid epidemiological studies and be a useful tool in the management and control of Johne's disease.  相似文献   

13.
OBJECTIVE: To evaluate pooled faecal culture for herd diagnosis of caprine Johne's disease and relate these findings to faecal shedding rates of Mycobacterium avium subsp paratuberculosis (Map). DESIGN: Radiometric broth culture was applied to several pooling dilutions, and shedding rates were estimated from a regression equation based on bacterial growth rates and known processing losses during radiometric culture. PROCEDURE: Sixteen faecal samples from goats naturally infected with sheep (n = 3) or cattle (n = 13) strains of Map, were diluted in normal goat faeces from 1 in 5 to 1 in 50. Cultures were confirmed by IS900 polymerase chain reaction and restriction endonuclease analysis, and mycobactin dependency. The numbers of viable Map in the culture inocula were determined by endpoint titration (most probable number) of nine samples and related to a cumulative growth index. RESULTS: A pooling dilution of 1 in 25 with an incubation period of 10 weeks detected 13 of 16 culture positive goats, all shedding > or = 2 x 10(4) Map per gram of faeces. Two samples containing very low numbers of Map (< 2 x 10(3)/g) were only culture positive from undiluted faeces. Thirteen of 16 goats were considered to be shedding low to moderate concentrations of Map (< 2 x 10(5)/g faeces). CONCLUSIONS: These data support a pooling dilution of 1 in 25 for application of pooled faecal culture as a diagnostic tool in caprine Johne's disease control. A test based on this dilution would reduce laboratory costs of whole herd testing in goats by approximately 40% relative to serology and 75 to 90% relative to individual faecal culture.  相似文献   

14.
A study was conducted to determine whether trichostrongylid nematode larvae become contaminated with Mycobacterium avium subsp. paratuberculosis when they develop in the faeces of sheep with Johne's disease. Nematode larvae were hatched from ova in the faecal samples of affected sheep. Larval sheaths were removed and these as well as exsheathed larvae were subjected to radiometric culture for M. paratuberculosis. The organism was recovered from washing water used to prepare the larvae, third stage larvae and larval sheaths, but not from exsheathed larvae. The recovery of M. paratuberculosis from larvae was associated with the severity of the histological lesions in affected sheep and with the results of culture of the organism from intestinal tissues and faeces. Nematode parasites of sheep might be able to act as mechanical vectors for M. paratuberculosis as the organism associates with infective third stage larvae when these develop in the faeces of sheep with Johne's disease.  相似文献   

15.
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   

16.
A questionnaire survey regarding endoparasite control practices in Danish horse herds was carried out in 1995. The participating veterinarians and herd owners were sampled using convenience and purposive sampling. In the analysis of risk factors for development of a high endoparasitic burden (> 200 eggs per gram faeces) 903 horses were sampled and the analysis of the efficiency of a single anthelmintic treatment was based on 605 horses. The following factors had a significant effect on the endoparasitic burden: herd type, age of the horses, use of pasture rotation, anthelmintic treatment of horses visiting the herd, use of an adviser in the planning of endoparasite control and advice regarding pasture rotation. An interaction between pasture rotation and advice regarding pasture rotation was found, but due to high colinearity this was not reported. The factors influencing significantly on the reduction of the faecal egg count after a single anthelmintic treatment were the type of herd, the age of the horse, the drug used, and the anthelmintic-resistance-status of the herd. A negative effect of permanent pastures was observed. If pasture hygiene was performed on the advice of the veterinarian, the effect of a single anthelmintic treatment was less compared to a single anthelmintic treatment without any advice. An interaction between the treatment group and the resistance-status of the herd was found. Additional factors, normally accounted for, when endoparasites and anthelmintic resistance is discussed, were investigated, but not found significant in this study.  相似文献   

17.
The epidemiology of Nematodirus battus infection under a husbandry system based on an annual alternation of sheep and cattle was studied from 1983 to 1985. Pasture larval levels and sheep and cattle worm egg outputs were monitored from April to September each year. The level of N battus contamination on the sheep pasture and the number of clinically affected lambs increased over the three years despite grazing with cattle in the intervening year. Examination of cattle faeces demonstrated that six-month-old calves excreted moderate numbers of N battus eggs in June and July, thus contaminating next season's sheep grazing.  相似文献   

18.
鸭茅╋白三叶型混播放牧草地肉牛生产系统优化研究   总被引：1，自引：1，他引：0  
在鸭茅（Dactylis glomerata）+白三叶（Triflium repens）草地型肉牛放牧系统内,实施全日制划区轮牧、载畜量季节性调控、维持肥施用、草地除杂、枯草期补饲等优化措施,对草地的土壤养分、牧草生长强度、现存量、组分、养分及肉牛体质量、日增体质量等指标进行了监测。结果表明,采用全日制放牧,在草地年平均载畜量1.4牛单位/hm2下,牧草的生长量超过8 077 kg/hm2,肉牛体况得到明显的改善,单位草地面积经济效益可达1 135元/hm2,草地实现可持续利用。同时,针对草地肉牛放牧系统中存在的问题,提出了有效改进的合理化建议。  相似文献   

19.
Paratuberculosis (Ptbc) has a high prevalence in Argentina, that affects dairy and beef cattle. The culture is the gold standard to the diagnosis of the disease. Mycobacterium avium ssp. paratuberculosis (M. paratuberculosis), the aetiological agent, is difficult to isolate and grow in culture. In this study, 24 randomly selected cows of the Fresian breed from a dairy herd with a history of Ptbc were used to evaluate the performance of different diagnostic techniques. These animals did not show clinical signs of the disease. However, another animal from this herd presented evidence of clinical disease at the moment of the present study. This animal was necropsied and one strain of M. paratuberculosis was isolated from faeces, lymph nodes and intestine. Serum for indirect absorbed enzyme-linked immunosorbent assay (ELISA) and agar gel immunodiffusion (AGID) tests and whole blood samples to perform gamma interferon (gammaIFN) release assays were obtained from each animal. Faeces and milk samples to carry out bacteriological cultures, PCR identification of M. paratuberculosis, and direct examinations of smears with Ziehl-Neelsen's (ZN) stain were also collected. Tuberculin test with bovine purified protein derivative (PPD) in the caudal fold was performed. The results showed that 10 out of 24 animals (41.6%) were positive to ELISA. Eight strains of M. paratuberculosis were isolated, six from faeces, two from milk. Five of the animals that excreted the bacteria through faeces were ELISA-positive, whereas the excreters through milk were negative to ELISA. No positive samples by AGID were obtained in clinical asymptomatic animals. Seven samples gave positive gammaIFN results with avian PPD, but only two of these animals were confirmed with culture. Direct PCR, to detect IS900 (M. paratuberculosis) in faeces and milk samples, was negative, but PCR using material taken from faecal and milk cultures gave positive results before visualizing the colonies. No sample was positive by PCR directed to IS6110 (M. tuberculosis complex). There was not always agreement between isolations and ZN in the studied samples. In conclusion, the absorbed ELISA was useful to detect positive animals and excreters through faeces but not through milk. PCR applied to cultures with incipient development before the visualization of colonies was effective to specifically determine the presence of M. paratuberculosis. The gammaIFN test was not able to detect the most positive animals confirmed by culture. The importance of using ELISA and cultures is emphasized by this study but it is necessary to continue with the gammaIFN test development for early detection of the disease.  相似文献   

20.
A five year ley pasture was used as a source of natural infection with Dictyocaulus viviparus for cattle in anthelmintic trials. Pasture larval counts, faecal larval counts of permanently grazing calves and lungworm burdens harboured by tracer calves were monitored in three grazing seasons to assess the pattern of infection. Carrier calves were introduced at the beginning of the grazing season in the first two years of the study but not in the third. In the fourth year the pasture was subdivided into two paddocks where overwintered infection with and without carrier infection were compared. A control paddock exposed to carrier infection but no overwintered infection was also monitored. Pasture larvae survived the winter but carrier infection appeared to make a larger contribution to pasture larval counts and the onset of parasitic bronchitis in susceptible calves. In the absence of grazing cattle at the end of the grazing season the concentration of D viviparus larvae on the herbage fell rapidly to undetectable levels. Discrepancies between contamination of herbage by infective D viviparus larvae and infectivity of pasture for susceptible cattle occurred in all years but were particularly marked on the third year when natural immunity appeared to influence the number of lungworms accumulating in tracer calves. Failure to recover lung worms from tracer calves cannot be regarded as an accurate indication of lungworm free pasture. In the first three years the proportion of the lungworm population which was inhibited in tracer calves was higher early and late in the grazing season and negligible in mid season. This suggests that a predisposition to inhibition in larvae which have overwintered on pasture may influence the time of onset of parasitic bronchitis in the next grazing season, but results from the fourth year did not support this hypothesis.  相似文献   

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