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1.
A study was conducted over 3 years (1998-2000) to investigate larval availability of gastrointestinal nematodes from faeces of cattle reared under different parasite control schemes. These cattle were part of a parallel, but separate grazing trial, and were used as donor animals for the faecal material used in this experiment. At monthly intervals, faeces were collected and pooled from three groups of first-season grazing cattle. These groups were either untreated, ivermectin bolus treated or fed the nematophagous fungus Duddingtonia flagrans. The untreated and fungus treated animals were infected with gastrointestinal nematodes and the number of eggs per gram (epg) pooled faeces ranged between 50 and 700 in the untreated group and between 25 and 525 epg in the fungus treated group. Each year between June and September, artificial 1 kg dung pats were prepared and deposited on pasture and protected from birds. The same treatments, deposition times and locations were repeated throughout the study. Larval recovery from herbage of an entire circular area surrounding the dung pats was made in a sequential fashion. This was achieved by clipping samples in replicate 1/4 sectors around the dung pats 4, 6, 8 and 10 weeks after deposition. In addition, coinciding with the usual time of livestock turn-out in early May of the following year, grass samples were taken from a circular area centred where the dung pats had been located to estimate the number of overwintered larvae, which had not been harvested during the intensive grass sampling the previous year. It was found that recovery and number of infective larvae varied considerably within and between seasons. Although the faecal egg counts in 1999 never exceeded 300 epg of the faecal pats derived from the untreated animals, the abnormally dry conditions of this year generated the highest level of overwintered larvae found on herbage in early May 2000, for the 3 years of the study. Overall, biological control with D. flagrans significantly reduced larval availability on herbage, both during and between the grazing seasons, when compared with the untreated control. However, the fungus did not significantly reduce overwintered larvae derived from early season depositions (June and July), particularly when dung pats disappeared within 2 weeks after deposition. Very low number of larvae (<3 per kg dry herbage) were sporadically recovered from grass samples surrounding the ivermectin bolus faecal pats.  相似文献   

2.
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   

3.
A series of experiments was carried out to examine the effects of two different isolates of the nematode-trapping fungus Duddingtonia flagrans to reduce the number of free-living larvae of the bovine lungworm, Dictyocaulus viviparus. A laboratory dose-titration assay showed that isolates CI3 and Troll A of D. flagrans significantly reduced (P < 0.05 to P < 0.001) the number of infective D. viviparus larvae in cultures at dose-levels of 6250 and 12,500 chlamydospores/g of faeces. The larval reduction capacity was significantly higher for Troll A compared to CI3 when lungworm larvae were mixed in faecal cultures with eggs of Cooperia oncophora or Ostertagia ostertagi and treated with 6250 chlamydospores/g of faeces. Both fungal isolates showed a stronger effect on gastrointestinal larvae than on lungworm larvae. Two plot trials conducted in 1996 and 1997 involved deposition of artificial faecal pats containing free-living stages of D. viviparus and C. oncophora on grass plots. Herbage around the pats was collected at regular intervals and infective larvae recovered, counted and identified. These experiments showed that both D. flagrans isolates reduced the number of gastrointestinal as well as lungworm larvae in faecal pats. During both plot trials, the transmission of C. oncophora larvae, but not D. viviparus, from faecal pats to the surrounding herbage was clearly affected by climatic conditions. After collection of faecal pats from the grass plots one month after deposition, the wet and dry weight of pats as well as organic matter content were determined. No differences were found between the fungus-treated and non-treated control pats. This indicated that the rate of degradation of faeces was not affected by the addition of the fungus.  相似文献   

4.
This paper reports the findings of two trials into the effects of the treatment of cattle with ivermectin slow-release (SR) bolus on the larval development of the dung beetle Aphodius constans Duft. Rectal faecal samples were collected prior to treatment and every 3 and 2 weeks in a first and second trial, respectively, and up to 156 days post-administration of the SR bolus. Faecal ivermectin concentration reached a peak at 63 days post-treatment (1427 ng g(-1)) and ivermectin was detected up to 147 days post-treatment in the first trial (7.2 ng g(-1)). First stage larvae of A. constans were reared with control or contaminated dung and adult beetles were counted after emergence. In the first trial, the comparison of pairwise samples showed that ivermectin prevented the development of larval A. constans until day 105, while at day 135 the rate of emergence was still significantly lower than the corresponding series of control (p < 0.05). In the second trial, the difference between control and treated series remained significant until 143 days post-treatment, with no emergence until 128 days post-administration of SR bolus to cattle. These results show the negative effect of ivermectin on the development of larval A. constans, even at a low concentration (38.4 ng g(-1)). The administration of ivermectin sustained-release bolus to cattle was highly effective in killing dung beetle larvae for approximately 143 days after treatment. The results were similar when dung was obtained from a single animal kept alone, or from a blending of faecal pats obtained from a group of animals kept in field conditions during the whole trial period.  相似文献   

5.
Abstract

The effect of urine and dung deposition on the patch grazing patterns of cattle and sheep in the Southern Tall Grassveld was investigated using an experiment with four treatments, viz. artificial urine, fresh cattle dung, fresh sheep dung, and a control. Cattle and sheep preferentially grazed the sward surrounding and within urine deposits for six months after deposition. Cattle rejected herbage from both cattle and sheep dung patches for six months after deposition. Sheep initially rejected the herbage from cattle dung patches, but their grazing patterns were no longer affected at six months after deposition. Sheep grazing tended not to be influenced by sheep dung. Urine deposition may consequently be an important factor in patch initiation and patch development.  相似文献   

6.

Management of nematode parasites of grazing livestock is essential, but there is concern about the potential environmental risk from agents used in their control. In this experiment, parasites in young cattle were controlled, using ivermectin boluses or the predacious fungus Duddingtonia flagrans , over 3 years. Treatment differences were sought among the soil nematodes recovered from soil samples collected from the paddocks on which treated animals grazed, and compared with similar samples taken from an untreated control paddock. Analysis of the soil nematode fauna on 21 occasions failed to demonstrate any impact of parasite management on soil nematodes. In 0-22 mm soil total nematode abundance averaged 524 000 m -2 , with 18 nominal taxa and H' diversity 2.41. There were both underlying paddock and year-to-year, climate-related, differences. The results of this trial not only confirm the lack of any adverse environmental impact of D. flagrans , a promising biological control agent, on soil nematodes, but also fail to show any impact arising from the use of ivermectin boluses.  相似文献   

7.
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   

8.
Investigations were made into the timing of administration of Duddingtonia flagrans as a biological control agent against ovine parasitic nematodes including stongylid and Nematodirus spp. Faeces from 3-4 months old male lambs were deposited onto pasture plots that had never been grazed by sheep. The trial was conducted over two consecutive years (1998 and 1999). For both years, the following three plot types were involved: Sim plots had faeces containing nematode eggs and Duddingtonia flagrans spores deposited simultaneously; Post plots had faeces containing nematode eggs followed 2 weeks later by faeces containing D. flagrans spores alone; Control plots had faeces containing only nematode eggs; Prior plots (included in 1999) had faeces containing D. flagrans spores alone followed 2 weeks later by faeces containing nematode eggs. In each year, two deposition periods were involved: July and August in 1998 and June and July in 1999. During the first year pasture samples were collected at 2, 4, 6, 8 and 12 weeks after initial deposition. In 1999, additional samples were collected at 10, 16 and 20 weeks. Larvae were extracted from the pasture samples and counts performed to estimate the number and species of infective third-stage (L(3), larvae) present. The number of third-stage strongylid larvae on pasture was significantly lower on Sim plots compared to the remaining plot types for both years at all deposition times (P<0.001). This was also the case for the number of Nematodirus infective larvae in August deposition plots in 1998 (P<0. 02). There was no significant difference between treatments in both deposition times in 1999 and July deposition plots in 1998 for the Nematodirus data. These results suggest that D. flagrans, if deposited at the same time as parasite eggs prevents transmission of third-stage larvae from the faecal deposit onto pasture, including occasionally Nematodirus species, but does not have an effect on third-stage parasitic nematode larvae in the surrounding soil.  相似文献   

9.
A three-year grazing experiment (1998-2000) was conducted with first-season grazing cattle (FSGC) on improved pastures in central-eastern Sweden. Comparison was made between five groups with 10 calves in each group where four of these were set stocked and either (1) untreated, (2) ivermectin bolus treated, (3) subjected to biological control with the nematophagous fungus Duddingtonia flagrans, or (4) treated with a copper wire particle bolus. The fifth treatment was an evasive grazing strategy, whereby untreated calves were turned out onto pasture used by older cattle the previous year and then these calves were moved to silage aftermath in mid-July. To introduce low-levels of parasite infection to the experiment, each animal received a 'priming dose' of approximately 5,000 Ostertagia ostertagi and 5,000 Cooperia oncophora infective third stage larvae immediately prior to the start of the first grazing year of the trial.Results showed that efficient and sustainable parasite control of FSGC was possible to achieve without the use of anthelmintics by using turnout pastures that the previous year had been grazed by older cattle, in combination with a mid-July move to aftermath leys. Biological control also proved beneficial but the efficacy was impaired if high faecal egg counts coincided with rapid dung pat degradation due to heavy rainfall. No indication of parasite control was observed with the copper wire particle bolus. It was also demonstrated that the impact of gastrointestinal (GI) parasitism varied between years and that the level of overwintering contamination is important but likewise, is unpredictable. Although faecal egg counts in 1999 were low, due both to a delayed turnout and drought for the major part of the grazing season, deposited eggs successfully developed to infective larvae and overwintered in large numbers. The population of overwintered infective larvae at the time of turnout in early May played an important role in the course of infection in 2000 and resulted in an average 65 kg advantage of the ivermectin treated calves compared with the untreated calves.Thus, this three-year grazing experiment has emphasised the importance of subclinical gastrointestinal nematode infections in FSGC in Sweden. In addition, the study has shown that adequate parasite control may be achievable without the use of anthelmintics.  相似文献   

10.
An experiment was carried out in 1997 to test the efficacy of an isolate of the microfungus Duddingtonia flagrans against free-living stages of horse strongyles under conditions in the field and to assess the eventual effect of the fungus on the normal degradation of faeces. Faecal pats were made from faeces of a naturally strongyle infected horse, which had been fed fungal material at a dose level of 106 fungal unit/kg bwt. Control pats without fungi were made from faeces collected from the same animal just before being fed fungi. Faecal cultures set up for both groups of faeces to monitor the activity of the fungus under laboratory conditions showed that the fungus significantly reduced the number of infective third-stage larvae (L3) by an average of 98.4%. Five faecal pats from each batch of faeces were deposited on pasture plots at 3 times during spring-summer. The herbage around each pat was sampled fortnightly to recover L3 transmitted from faeces. The results showed that the herbage infectivity around fungus-treated pats was reduced by 85.8-99.4%. The remaining faecal material at the end of each sampling period was collected, and the surviving L3 were extracted. Significantly fewer larvae were recovered from the fungus-treated pats. Analysis of wet and dry weight of the collected pats, as well as their organic matter content, were performed to compare the degradation of faeces of both groups. The results indicated that the presence of the fungus did not alter the degradation of the faeces.  相似文献   

11.
In a series of five laboratory experiments observations were made on the role of Pilobolus in the translation of infective lungworm larvae from faeces of cattle. The results indicated that a substantial proportion of the lungworm larvae present in the faeces may be translated from the faeces by this fungus within eight days at a temperature of 15 degrees C. No clear relationship was observed between the numbers of Pilobolus and the translation of lungworm larvae. Further a longitudinal study on the occurrence of Pilobolus on faecal pats of grazing calves showed that between the beginning of July and the middle of September peak emergence of sporangia generally occurred within one week and most sporangia emerged within three weeks. From faecal pats which had been deposited at the end of September and the middle of October emergence of sporangia was lower and mainly occurred after two to four weeks.  相似文献   

12.
Objective: To assess the toxicity of residues of ivermectin and moxidectin in cattle faeces collected at intervals after treatment.
Design: Replicated bioassays of faeces using larvae of the bush fly, Musca vetustissima and the house fly, Musca domestica .
Animals: Two groups of five Murray Grey x Aberdeen Angus steers were treated with injectable formulations of ivermectin and moxidectin respectively. A third group was used as an untreated control.
Procedure: Newly emerged fly larvae were reared in the dung of treated animals.
Results: Drug residues in faeces collected 3 to 35 days after treatment with an injectable formulation of moxidectin had no significant effect on the survival of larvae of M vetustissima . Similarly, faeces dropped up to seven days after treatment caused no significant reduction in larval survival in M domestica . In day 2 dung, residues of moxidectin delayed development of M vetustissima larvae, but had no effect on their survival. In contrast, ivermectin-treated steers, produced dung that inhibited larval development of both M vetustissima and M domestica for 7 to 14 days after treatment. Significant reductions in survival of M vetustissima larvae occurred in dung collected on days 21 and 28 after treatment, but by day 35 survival did not differ from that in control dung.
Conclusion: Excreted faecal residues of moxidectin are relatively innocuous to larvae of both M vetustissima and M domestica . Those of ivermectin inhibit survival for 7 to 14 days after treatment and are likely to have adverse effects on non-target organisms.  相似文献   

13.
The control of ruminant gastrointestinal nematodes and ectoparasites, one of the major production health problems, are heavily reliant on the systematic and sometimes abusive use of anthelmintic drugs. Endectocides are the most frequently used drugs, having high potency against arthropods and nematodes. Their dung pat residues enhance the risk of adverse effects on non-target invertebrates and on the general grazing cattle ecosystem. In this scenario, our objective is to review current knowledge of the agro-environmental and biodiversity impact and risks of endectocides in South America. The effects of faecal drug residues of ivermectin and doramectin on dung colonising invertebrates and dung degradation have been reported in studies carried out in the temperate centre of Argentina and in the subtropical region of Brazil. The results from Argentina showed a depression in invertebrate colonisation and degradation of dung recovered from endectocide treated cattle during the autumn. Comparisons have shown that ivermectin and doramectin have similar adverse effects. A decrease of Coleoptera larvae, Diptera larvae, Staphylinidae, Collembola, Acari and dung specific nematodes was noted in pats from both endectocides. The results from Brazil showed that dipterous larvae, Polyphaga coleopteran larvae and adults and mites were significantly reduced in the ivermectin treated group. The disturbances that macrocyclic lactones can produce on non-targeted invertebrates and on their associated participation in dung degradation and soil element recycling, are unpredictable and can negatively influence biodiversity and the agricultural ecosystem sustainability.  相似文献   

14.
Effective alternatives to anthelmintic treatment against nematode parasites of goats are required because of the high prevalence of benzimidazole resistance. Towards this objective, the nematophagous fungus, Duddingtonia flagrans (Df), was used in a plot study against two main parasitic nematode species of goats, Teladorsagia circumcincta (Tcir) and Trichostrongylus colubriformis (Tcol). Worm-free, culled goats were experimentally infected with strains of Tcir and Tcol to constitute donors. Half of the animals were periodically given Df chlamydospores at a daily dose of 2.5 x 10(5) spores/kg BW while the remaining animals were kept as controls. At 5 time periods i.e. March, May, July, September and November 2001, corresponding to the main grazing season in France for goats, faeces were collected from the 6th day of fungus administration for the following 2 days to obtain approximately 1 kg of faeces from each group of animals: Tcir/Control, Tcol/Control, Tcir/Fungus, Tcol/Fungus. For each period and each group, the faeces were deposited on a 1 m2 grass plot and the grass was cut (3 replicates) on weeks 2, 4, 6, 8,12 after deposition, for infective larval recovery. Larvae were counted and the results were expressed as a ratio of larvae/eggs deposited. On the plots with the control faeces deposited in March, July and September, the grass infectivity due to Tcir and Tcol was similar and the maximum number occurred between 2 and 4 weeks post deposition. In May, the maximum numbers of larvae were not recorded until 8 weeks after deposition, due to high daily temperatures and dryness. In November, larval development took place only for Tcir. On the plots with the fungus treated faeces, a significant reduction in grass infectivity occurred for both nematodes and ranged from 50-60% in May, July and November deposits to 80-90% in the September deposit. On the contrary to these findings, no difference was recorded between the fungus and control plots for the March deposit. In conclusion, D. flagrans is suitable for reducing the number of infective larvae in the herbage during the main part of the grazing period for the most important digestive nematodes of goats.  相似文献   

15.
The nematode-trapping fungus Duddingtonia flagrans may be used in biological control of parasitic nematode larvae in faeces of domestic host animals after feeding the hosts with fungal chlamydospores. In this experiment a possible undesirable fungal impact on earthworms, of the species Aporrectodea longa, was investigated. As earthworms eat animal faeces, D. flagrans may come into contact with earthworms both in their alimentary tract and on their body surface. However during the experimental period of 20 days, when earthworms were living in soil and eating cattle faeces that were heavily infested with viable chlamydospores of D. flagrans there were no indications of internal or external mycosis among the earthworms.  相似文献   

16.
The repeatability of detection of Mycobacterium avium subsp. paratuberculosis (Map) within and between samplings from 16 paratuberculous dairy cows (13 subclinical; 3 clinical) was investigated by radiometric culture of quadrants of faecal dung pats collected on four to seven occasions over a 10-16-day period. Results were compared to serological status and to pathological and bacteriological findings in multiple tissues obtained at slaughter from 15 of the animals 2-6 weeks after the faecal samplings. From faecal samples taken on 77 occasions over the 2-week period, 296/308 (96%) quadrants were culture positive, with samples from all cattle showing evidence of faecal shedding of Map. Histological lesions typical of paratuberculosis were present in 14 of the 15 cows examined at slaughter, varying in severity from mild (two animals) to moderate (4) and advanced (8), and all predilection tissue sites yielded Map. The negative faecal samples were derived from a single animal that was culture positive in two quadrants on each of the first two (of four) sampling occasions (i.e. culture positive in only 4 of 16 collected quadrants). This animal was found to be histologically negative at slaughter, and culture positive from three of five predilection tissue sites. Faecal samples from cows with subclinical and clinical paratuberculosis, with lesion severity ranging from mild to severe at multiple predilection sites, produced faeces with relatively consistent concentrations of Map within samples. There was significant variation in concentrations of Map between samples in individual animals over a period of 2 weeks, but this did not affect the dichotomous positive-negative culture status for 15 of the 16 cattle. A faecal sample collected non-randomly per rectum thus provides a representative specimen for detection of Map by radiometric culture on a single sampling occasion.  相似文献   

17.
On a series of pasture plots, 2 kg pats of bovine faeces containing known numbers of strongylid (Haemonchus, Cooperia, Oesophagostomum and Trichostrongylus) eggs were deposited at intervals of 4 weeks from July 1995 to June 1996. The plots were sampled every 2 weeks after contamination and infective larvae were identified and counted. Larvae of all the genera developed throughout the year, but the pats exposed during the rainy season yielded more abundant larvae on the herbage. Irrespective of the season of deposition of the pats, larvae were found in larger numbers from 2 to 6 weeks after deposition and generally declined to below detectable levels within 12 to 16 weeks of contamination. The comparatively short survival times noted in this experiment may present opportunities for manipulation of the population dynamics of the gastrointestinal nematodes in the tropical environment of Kenya.  相似文献   

18.
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   

19.
The size and composition of the nematode assemblage in soil under faecal pats derived from young cattle treated or untreated with either ivermectin sustained-release boluses, or the nematophagous fungus Duddingtonia flagrans, were studied in each of three years. Soil samples taken 4, 6, 8 and 10 weeks after four deposition dates in 1998 showed significant temporal effects in many taxa and treatment effects in a few genera. In 2000, soil samples taken 10 weeks after deposition in July, August and September showed treatment effects in the plant-associated Tylenchus and Cephalenchus, and the bacterial-feeding Cephalobus 1 and Cephalobus 2 taxa. However, overall it was found that the nematode assemblages were similar below all three types of pat, and the assemblages varied with the season of deposition. D. flagrans, the novel biological control agent being tested against the free-living stages of nematode parasites of cattle, had no detectable impact on the size or the structure of the soil nematode communities under the faecal pats.  相似文献   

20.
Pristionchus maupasi, a soil nematode, was used to elucidate the potential ecotoxic effect of the two anthelmintics fenbendazole and ivermectin in cattle dung. The population growth of P. maupasi was greater in faeces from cattle harbouring active Panacur- or Ivomec-boli, which are releasing fenbendazole and ivermectin to the rumen, respectively, compared to the growth in control faeces. In dose-response experiments it could be shown that the pure chemical compound of fenbendazole was increasingly nematocidal to P. maupasi in concentrations from 10 to 20 microg/g faeces (ww, i.e. wet weight) and the pure compound of ivermectin was effective above 3 microg/g faeces (ww). The results indicate that neither fenbendazole nor ivermectin have any acute toxic effect on P. maupasi in naturally excreted concentrations of the pure drugs, together with their metabolites in faeces from bolus-treated cattle. Both drugs are excreted in concentrations that are non-toxic to P. maupasi.  相似文献   

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