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1.
On the Persistence of Infective Ostertagia ostertagi, Cooperia oncophora and Nematodirus helvetianus on Pastures 
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下载免费PDF全文 H. J. Smith 《Canadian journal of veterinary research》1972,36(4):333-338
By grazing parasite-free susceptible calves on naturally infected paddocks for eighteen day periods, Nematodirus helvetianus was shown to survive over two winters on marshland pastures under Maritime climatic conditions in three successive years although the numbers surviving the second winter in two of the three years were low. Climatic conditions of below normal temperatures and little snowfall would appear to have a detrimental effect on the survival of Nematodirus over a second winter although large numbers did survive one winter of such adverse weather. However, under certain conditions, large numbers of Nematodirus can overwinter two years on pastures since over 12,000 worms were picked up by individual calves grazing paddocks in 1969 which had been vacant since 1967.
The findings indicated that few, if any, Ostertagia ostertagi and Cooperia oncophora survive over a second winter under Maritime conditions. The sharp decline in numbers of infective Ostertagia and Cooperia on pastures during the first grazing season following pasture contamination observed in this and previous investigations indicate that few worms of these species survive longer than a year under Maritime conditions.
相似文献2.
Helminth infections in Danish organic swine herds 总被引：1，自引：0，他引：1
In nine organic swine herds, faecal excretion and pasture contamination by parasite eggs/larvae were studied in a period from March to October 1999. It was shown that the organic pigs were infected with Ascaris suum (28% of weaners, 33% of fatteners, 4% of sows), Trichuris suis (4% of weaners, 13% of fatteners, <1% of sows) and Oesophagostomum spp. (5% of weaners, 14% of fatteners, 20% of sows) whereas no infections with Hyostrongylus rubidus, Metastrongylus spp. or Strongyloides ransomi were detected. Moreover, no pigs showed clinical signs of infestations with scabies or lice. In the soil samples, very few Trichuris eggs were found throughout the season, whereas Ascaris eggs were found in 14% of the soil samples from sow pastures and in 35% from slaughter pig pastures, with the first infective eggs being recorded in July and the maximum number in August. Infective Oesophagostomum larvae were found in the grass samples in increasing numbers from May to October. Single herd cases of exceptionally high parasite infection levels are described in relation to herd management procedures. 相似文献
3.
The development and survival of the eggs of Haemonchus contortus on pasture at Vom were studied by depositing faecal pellets on grass plots over a period of 12 months. Development and survival to the infective larvae occurred throughout the study except during the dry season months of December to April. More infective larvae were recovered from the herbage in June, July and August than in other months. The survival time of the infective larvae ranged from 2 weeks in October to 10 weeks in June, July and August. Rainfall was the most important epizootiological factor influencing the development and survival of the infective larvae. Temperature was not a limiting factor. 相似文献
4.
Summary The efficacy of the oxfendazole pulse release bolus (OPRB) was tested in a grazing experiment at the University of Utrecht. Three groups of four OPRB‐treated calves and one group of four untreated control calves were grazed on separate pastures between 18 May and 21 October 1987. Based on faecal egg counts for strongyle‐type eggs and Nematodirus eggs, embryonation of Nematodirus eggs and faecal larval counts for lungworm, the first pulse of oxfendazole was released after 28 to 63 days, which was later than the period of approximately three weeks indicated by the manufacturer and others. As far as could be detected, the second to fifth pulses were not as delayed, but generally the three‐week period was also exceeded. This delayed release of the pulse resulted in a build‐up of pasture infectivity for gastrointestinal nematode larvae and lungworm larvae. Nevertheless, this did not result in clinical gastrointestinal helminthiasis and husk in the treated groups of calves, whereas severe husk and mild gastrointestinal helminthiasis were seen in the control group. 相似文献
5.
In a study originally designed to determine the seasonal origin of the high levels of availability of nematode larvae to cattle in winter and spring, plots were serially contaminated with eggs of Ostertagia ostertagi and Cooperia oncophora by naturally-infected calves at monthly intervals from February 1980 to September 1980. The availability of infective larvae was monitored by monthly pasture sampling and larval recovery. Because of the intervention of a 15 month drought, recoveries of larvae from the pastures were very low until March 1981 (autumn in Australia) when large numbers of larvae appeared on pastures contaminated in the preceding spring. Examination of dry dung pats at that time showed that significant numbers of larvae were present in pats deposited up to a year previously, and particularly in pats deposited in May, August and September. Following the resumption of normal rainfall in May 1981, larval numbers in pats rapidly declined and concentrations of larvae on the pastures increased to extremely high levels. It is suggested that survival of infective larvae in dry dung pats was enhanced by the drought, with implications for control of nematode infections of cattle, particularly in winter rainfall environments. 相似文献
6.
As part of a study on the epidemiology of Nematodirus species of sheep in subarctic Greenland, the development and persistence of eggs and larvae were investigated by experimentally contaminating plots of pasture with infected faeces and by placing tubes containing a suspension of eggs on to or into the soil. Despite low ambient temperatures, infective larvae appeared within a month during the summer. The greatest numbers of larvae were recovered from herbage in August and September. Eggs did not develop synchronously as development beyond the morula stage could be delayed for up to two years. Larvae were found on herbage for up to 37 months after faecal deposition. In the sheep rearing area of Greenland, therefore, Nematodirus species larvae can be present on herbage throughout the whole summer but peak numbers occur late in the grazing season. 相似文献
7.
Abstract AIMS: To measure the development of Teladorsagia (=Ostertagia) circumcincta and Trichostrongylus colubriformis eggs to third-stage infective larvae (L3) at different times of the year. Also, to measure the spatial distribution of L3 across herbage, soil and faeces, in order to assess whether spatial issues could be important in larval dynamics on pasture. METHODS: Field plots were contaminated with sheep faeces containing approximately 20,000 eggs of each of T. circumcincta and T. colubriformis on five separate occasions, viz 01 December 1996 (summer), 18 March 1998 (autumn), 17 June 1998 (winter), 15 October 1998 (spring), and 23 July 1999 (winter). Replicate plots (n=10) were harvested at intervals for up to 12 months after deposition of faeces, and the number and distribution of L3 were measured. Larvae were sampled from faeces (where these remained), herbage, and three soil zones to a depth of 145 mm. RESULTS: There were large differences between contamination dates in the percentage of eggs that developed to L3. For both species the highest percentage development was for eggs deposited in December (7.8% and 25.9% for T. circumcincta and T. colubriformis, respectively) and the lowest for June (0.4% and 0.03% T. circumcincta and T. colubriformis, respectively). Development in winter was often delayed, and this was always associated with a low yield of larvae, probably due to compounding mortalities associated with long periods of exposure to low temperatures. The relative distribution of L3 present on herbage, in faeces or in the soil varied between sampling times. However, overall the most L3 were recovered from soil (74% and 66% for T.circumcincta and T. colubriformis, respectively, averaged over all samples), and the lowest recoveries were from the herbage. CONCLUSIONS: Although the data are limited, the results indicated that the highest percentage of eggs developed to infective larvae in summer and only minimal development occurred in winter. The data do not support the view that substantial contamination of pastures with sheep parasites occurs over winter. Large numbers of larvae were recovered from soil, which indicates that, assuming they can subsequently migrate onto herbage, soil is a potentially important reservoir ofinfective larvae in New Zealand. Therefore, the spatial distribution of L3 on pasture may affect both the dynamics and transmission of parasite populations. Further work on both these issues is warranted. 相似文献
8.
H.-J. Bürger 《Veterinary parasitology》1976,1(4):359-366
Larval counts were made on herbage samples collected from 14 calf pastures and 14 cow pastures at each of three different localities in Lower Saxony, Western Germany, in September 1974. Significantly higher numbers of larvae of the genera Ostertagia, Cooperia and Nematodirus were demonstrated on calf pastures than on cow pastures in all three areas. The results suggest that, in the absence of available “clean” pasture, improved control of trichostrongyle infection during late summer and autumn might be achieved by the transfer of calves to cow pastures at that time. 相似文献
9.
Successive pairs of approximately 4-month-old Friesland bull calves, raised under worm-free conditions, were exposed to helminth infection for 14 days on dry-land Kikuyu grass pastures at 28-day to monthly intervals, on a coastal farm in a non-seasonal rainfall region of the Eastern Cape Province. With the exception of one pair of calves exposed for 28 days, this procedure was repeated for 28 consecutive months from December 1982 to March 1985. The day after removal from the pastures one calf of each pair was slaughtered and processed for helminth recovery and the other 21 days later. Both members of the last four pairs of calves were killed 21 days after removal from the pastures. Sixteen nematode species were recovered from the calves, and infection with Ostertagia ostertagi was the most intense and prevalent, followed by Cooperia oncophora. The calves acquired the greatest number of nematodes from the pastures from June to October of the first year and from June to August of the second year of the survey. Few worms were recovered from the tracer calves examined from November or December to March or April in each year of the survey. The seasonal patterns of infection with Cooperia spp., Haemonchus placei, Nematodirus helvetianus, Oesophagostomum spp., O. ostertagi and Trichostrongylus axei were all similar and were negatively correlated to atmospheric temperature and evaporation. Slight to moderate arrest in the development of fourth stage larvae occurred from July to September in Cooperia spp., April to July in H. placei, and August to October in O. ostertagi and Trichostrongylus spp. during the first year of the survey. Too few worms were present in the second year to determine a seasonal pattern of arrest. Species survival during the hot and windy summer months appeared to be achieved via a combination of arrested larval development and an ageing residual population of adult worms in the host, and a small extant population of infective larvae on the pastures. 相似文献
10.
Strongylid parasites of horses: experimental ecology of the free-living stages on the Canadian prairie 总被引：1，自引：0，他引：1
L Polley 《American journal of veterinary research》1986,47(8):1686-1693
Each month for a 1-year period (October through September), equine fecal masses containing eggs of strongylid nematodes were placed outdoors on small grass plots in Saskatchewan, Canada. Thereafter, feces and grass from the plots were sampled after intervals of 1 week or longer, and the strongylid eggs and larvae recovered were counted. These observations were made over a 2-year period. Development of eggs to infective larvae occurred in all experiments, except those established in October, December, and January. Infective larvae from experiments set up in April through September survived that winter. During the summer, there was a gradual build up of infective larvae in the fecal masses, which reached a peak in August and September and then decreased into the winter. These results are discussed in the context of the control of strongylid parasites of horses on the Canadian prairie and in other areas of the world with a similar climate and similar horse management practices. 相似文献
11.
In studies on the control of parasitic gastroenteritis in calves and sheep, involving an annual rotation of pastures grazed by these host species, it was shown that young cattle could play an important role in the epidemiology of Nematodirus battus, a species usually regarded as a parasite of lambs. Thus, young cattle readily acquired heavy burdens of N battus in spring and the contamination of pastures with eggs from these infections resulted in significant populations of larvae on the herbage, which were infective to both calves and lambs grazed on these pastures in the following year. Although the majority of the N battus eggs hatched in the spring, some hatched in the autumn. The calves developed a strong immunity to N battus during the grazing season as demonstrated by the absence of worms at necropsy in the autumn, despite the presence of infective larvae on the pasture. 相似文献
12.
The Development, Clinical Signs and Economic Losses of Gastrointestinal Parasitism in Feeder Cattle on Irrigated and Non-irrigated Dikeland and Upland Pastures 下载免费PDF全文
下载免费PDF全文 Investigations were carried out over three grazing seasons with parasitized and treated (control) steers on irrigated and non-irrigated upland and dikeland pastures. The stocking rate in each paddock was adjusted by either adding or removing animals so as to maintain as uniform a sward and rate of grazing as possible. Animals were weighed on and off the pastures and fortnightly during the grazing seasons.
During the first grazing season clinically normal steers shedding low numbers of gastrointestinal worm eggs contaminated the parasite-free pastures sufficiently to give rise to large residual pasture infections and clinical parasitic gastroenteritis in grazing stock during the second grazing season. Worm burdens of 100,000 to 200,000 Ostertagia ostertagi and Cooperia oncophora were established in several steers showing marked clinical signs. In spite of treatments with high dosages of thiabendazole in attempts to keep worm burdens at a minimum, there was a slow but gradual buildup of pasture infections in the paddocks grazed by the control steers over the three year period.
During the second and third grazing seasons there were significant differences in the daily rate of gain between the parasitized and control animals on both upland and dikeland pastures. The parasitized groups of steers had daily rates of gain ranging from 0.29 to 0.80 pounds less than their comparable control groups.
Under Maritime conditions, irrigation did not have a consistent effect on weight gains and development of parasitism.
相似文献13.
The seasonal changes in nematode populations of a flock of sheep in the Montreal area were determined using serial fecal egg counts, fecal culture of larvae and necropsy worm counts. It was found that Ostertagia spp.,Nematodirus spp., Trichostrongylus agei, Trichostrongylus spp. and Chabertia ovina over-wintered on pasture and could initiate patent infections the following spring. The development of populations of H. contortus was typical of that seen with most of the other species and was characterized by the following series of events. In early winter when the study was started with stabled pregnant ewes, most of the populations were immature and the egg counts were low and remained so throughout the entire winter. However, in the spring, following lambing, large numbers of adult worms were seen with a consequent decrease in immatures and a sudden increase in egg counts. When the ewes and lambs were pastured together, the egg counts in ewes dropped consequent to “self-cure”, the “spring-rise” providing the major source of overwhelming infections for lambs with deaths by the end of July. As the season progressed larvae taken in by both ewes and lambs did not mature, and by early fall, most of the worm population consisted of immature forms. It appeared that H. contortus could not have more than two generations in ewes or lambs in a single grazing season. 相似文献
14.
Eysker M Bakker N Kooyman FN van der Linden D Schrama C Ploeger HW 《Veterinary parasitology》2005,133(4):313-321
During 2003 a grazing study was performed at Utrecht University to evaluate evasive grazing and application of Duddingtonia flagrans for the control of parasitic gastroenteritis in sheep. However, the summer of 2003 (June-August) was unusually warm and dry. As a result the patterns of gastrointestinal nematode infections deviated from those observed in more average years. The proportion of eggs that developed to infective larvae was far lower than normal in July-August. On the other hand, survival of larvae that had developed before the middle of July was not affected compared to other years. In fact, severe haemonchosis was observed in (tracer) lambs grazed at the end of July on pastures that had been contaminated from 26-05 to 16-06 and from 16-06 to 07-07. Moreover, tracer lambs grazing in September on some of these plots still acquired large Haemonchus contortus burdens. Over 60% of H. contortus that had established before the middle of July appeared to be able to survive until October in the virtual absence of re-infection. That may have consequences for the application of evasive grazing as a control option in that suppression of adult burdens might still be necessary, through a limited use of anthelmintics or through alternative deworming strategies. 相似文献
15.
THE EPIDEMIOLOGY OF EQUINE STRONGYLOSIS IN SOUTHERN QUEENSLAND 1. The Bionomics of the Free-Living Stages in Faeces and on Pasture 总被引：1，自引：0，他引：1
A. W. English 《Australian veterinary journal》1979,55(7):299-305
SUMMARY Development of the free-living stages of strongylid nematodes of the horse to the infective stage occurred in faeces in all months of the year in southern Queensland, at a rate which depended on the season. Most rapid development to the infective stage occurred in the warmer months, with the hatching of strongyle eggs being completed in 2 days in summer. During the winter, egg hatching continued for over 2 weeks. Larval moults proceeded at a faster rate in summer—all larvae were infective in 7 days during the hottest months, but it was as long as 5 weeks before all were infective in winter. However, even though development was rapid in summer, survival rates varied from 1 to 10%, in contrast to the spring and autumn, when over 80% reached the infective stage. One percent of larvae in faeces survived for up to 20 weeks in autumn and winter, but for only 4 weeks in summer. These results highlight the inadequacy of short-term pasture spelling for all but the hottest months. Infective larvae were found on herbage in all months of the year, but greatest numbers were recovered in spring and early summer, and in autumn and early winter. The relationship of pasture infestation to migration of larvae from Paecal reservoirs in response to rain was clearly shown. Most infective larvae were found within 30 cm of faecal masses, and in fact 89% of all larvae isolated from herbage in this study were found within 15 cm of faeces. Migration of larvae from faeces to herbage occurred with falls of rain as small as 25 mm. Horse faecal masses dried out completely in 6–8 days in summer and in 14–16 days in winter. Strongyle larvae developed to the infective stage in faeces in the absence of rain, although many remained in the pre-infective stage and completed their development when rain fell. This study shows that massive contamination of pastures with the eggs of strongylid nematodes must be prevented in spring and autumn if susceptible young horses are not to be at serious risk. 相似文献
16.
After foaling, 6 mares and their foals were placed on equine parasite-free pastures. Observations of fecal nematode eggs and pasture larvae indicated peak cyathostome egg production occurred in late August and early September, with greatest numbers of larvae on the forage appearing during October. Two foals were necropsied for parasitologic evaluations at approximately 155 days of age. Both had approximately 100,000 adult cyathostomes, mostly Cylicostephanus longibursatus, Cylicocyclus nassatus and Cyathostomum catinatum. However, there were nearly 7 times more cyathostome larvae (189,004) in the foal necropsied in October, during the autumn rise in pasture larval populations, than in the foal examined in September (27,354). 相似文献
17.
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
18.
H. J. Smith 《Canadian journal of veterinary research》1973,37(3):320-322
Infecting parasite-free eight week old calves with 8,000 infective Nematodirus helvetianus larvae did not modify appreciably their response to a later heavy field challenge with N. helvetianus, Ostertagia ostertagi and Cooperia oncophora, although two of six animals did have smaller Nematodirus burdens. 相似文献
19.
A study was carried out on a ranch in the semi-arid area of Kajiado District in Kenya during the period July 2000 to June 2001 to determine the seasonal patterns of development and survival of gastrointestinal nematodes of sheep on pastures. A series of plots were contaminated with sheep faeces every month and pasture samples were collected weekly for the recovery and identification of larvae. The availability of infective larvae on naturally contaminated pastures was also monitored on the paddocks grazed by sheep and around the night pen and the watering point every month from July 2000 to June 2001. The results from the examination of the pasture samples indicated that rainfall distribution was the major factor governing the development and survival of the pre-parasitic stages. No parasitic larvae were detected from the plots contaminated during the dry months from July to October 2000, but development and translocation of infective larvae on pastures occurred on plots contaminated during the rainy seasons and soon after when relatively high moisture was present in the herbage (November 2000 to June 2001). During this period, peak larval counts occurred between the first and the second week post contamination, then declined to undetectable levels between week 4 and 16 post contamination. The lack of development of infective larvae during the dry season and the relatively rapid decline of their population during the wet season presents an opportunity for the use of pasture spelling as a means of helminth control in the study area. The availability of infective larvae on naturally contaminated pastures, around the night pen and around the watering point also followed the rainfall distribution pattern. Infective larvae were consistently recovered around the watering point throughout the study period. This indicated that the point is an important source of infection for sheep, especially during the dry season when other pastures are non-infective. 相似文献
20.
The Effects of Anthelmintic Treatments on the Development of Gastrointestinal Parasitism in Calves 下载免费PDF全文
下载免费PDF全文 H. J. Smith 《Canadian journal of veterinary research》1974,38(2):139-144
Fortnightly treatment of susceptible calves with 1-tetramisole during the first two months of continuous exposure to pastures residually heavily-infected with Ostertagia ostertagi, Cooperia oncophora and Nematodirus helvetianus did not prevent the development of clinical parasitic gastroenteritis, although the infections were not as severe as in nontreated calves. Development of resistance in treated calves was manifested by significantly smaller numbers of Cooperia eggs in utero (which were reflected by reduced fecal egg counts) and by significantly smaller Nematodirus worm burdens than in susceptible calves that commenced grazing coincident with cessation of treatment. The findings also indicated that resistance to Nematodirus helvetianus was slower in developing in treated than in nontreated infected calves. 相似文献