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1.
Worm egg counts of yearling Angora or Merino wethers grazing in mixed flocks at either 4/ha or 8/ha were observed over a 5 month period. Based on faecal egg counts infection levels in the sheep increased for the first 3 months and then decreased as the animals developed resistance. Egg counts in the goats did not decrease during the experiment. Post mortem worm counts indicated that there was a significant host species--stocking rate interaction on worm burdens of Haemonchus contortus adults and Ostertagia circumcincta adults and larvae. Goats had more H. contortus and O. circumcincta adults than sheep at the 8/ha stocking rate. At 4/ha goats had fewer O. circumcincta fourth stage larvae than sheep. There was no stocking rate effect on the numbers of Trichostrongylus axei or T. colubriformis. Sheep had more T. axei and fewer T. colubriformis than goats.  相似文献   

2.
OBJECTIVE: To relate trichostrongylid infections acquired by sheep during summer to prevailing weather conditions. PROCEDURE: Groups of worm-free 'tracer' sheep were put onto pastures, previously contaminated with trichostrongylid eggs, for successive periods of 2 weeks from December to March. After grazing the sheep were housed for 6 weeks. Weekly worm egg counts and worm counts were used to estimate the numbers of worms acquired and related to weather conditions during the grazing period. RESULTS: No worm eggs were detected in the faeces of sheep that grazed at the end of January when only 7 mm of rainfall was recorded. At other times rainfall between 12 and 24 mm occurred and strongyle egg counts were generally either < 50 or > 150 eggs per g (epg). Mean counts of 1,100 Ostertagia and Trichostrongylus adults gave rise to mean counts of about 350 epg whereas about 6,000 Nematodirus spp were associated with mean egg counts of about 200 Nematodirus spp epg. CONCLUSIONS: Rainfall events during summer determine the numbers of trichostrongylid larvae acquired by sheep in summer but further studies are necessary before the implications for strategic control programs in southern Australia can be fully assessed.  相似文献   

3.
A new approach to the interpretation of faecal egg counts using a simple "formula", is described. It is suggested that adoption of this procedure may enable the likely level and frequency distribution of strongyle worm burdens (Nematodirus excluded) in young sheep flocks to be estimated. The potential relevance of this information to the diagnosis of gastrointestinal parasitism is discussed.  相似文献   

4.
In order to establish the infection pattern with gastrointestinal nematodes in ruminants in the central Kenya highlands, a study was carried out in 58 smallholder farms. The study involved monthly faecal examinations from sheep, goats and cattle and pasture sampling from eight communal grazing areas. Each month, six Dorper worm-free tracer lambs were introduced and four locally grazed cross-bred sheep were purchased for parasite recovery. The mean faecal egg counts (FEC) for cattle were low throughout the study period, whereas those for sheep and goats showed a seasonal pattern with high levels of infection occurring during the two main rainy seasons, especially in March, April and October. There were significant differences in egg counts over time and among farms. Haemonchus contortus was the most prevalent nematode in the tracer lambs whereas the previously exposed locally grazed sheep had significantly lower numbers of H contortus but significantly higher numbers of Trichostrongylus species The highest levels of infection in the tracer lambs occurred in November 1995 and January, May and June 1996. Based on this study, it is now possible to explore the possibility of using strategic treatments for the control of parasitic gastroenteritis in this area of Kenya.  相似文献   

5.
Helminths cause great economic loss in livestock in Africa, and can be categorized as either direct or indirect losses. Arid and semi-arid lands (ASAL) in Kenya comprise 71% of total land area and harbour the largest population of cattle, sheep and goats. However, little information on the distribution and impact of gastro-intestinal (GIT) parasitism in these animals is available. This survey was conducted to establish the prevalence of GIT parasites infecting calves, sheep and goats and their relative importance in Magadi division, which is semi-arid. Faecal samples were obtained directly from the rectum of 109 calves, 133 goats and 20 sheep and submitted to the laboratory for faecal worm egg counts, and coccidial oocysts examination using a modified McMaster method. The significance of differences in mean egg count per gram (epg) between animal species and herds (farms) were assessed using analysis of variance. The overall prevalence of nematodes in the calves, sheep and goats was 69.2%, 80% and 82%, respectively. About 10% of sheep and goats had epgs higher than 1 000, the remainder having light to moderate infections. The overall prevalence of coccidial oocysts in calves, sheep and goats was 30%, 44% and 45%, respectively. Poor productivity in ASAL areas, where nutrition is often poor, is likely to be pronounced in the presence of parasite infections. These findings indicate that viable internal parasite control should be implemented in the study area in order to increase the productivity of the livestock there.  相似文献   

6.
Romanov X Rasa Aragonesa ewes rearing twins and kept on pasture at a mean stocking density of 35 ewes ha-1 were used to study the epidemiology of parasitic gastro-enteritis under an intensive grazing system on irrigated land in the northeast of Spain. Measurements were made of the population of infective larvae on the pasture, level of serum pepsinogen, faecal worm eggs in ewes and lambs, and lamb growth rates. In addition, postmortem worm counts from "indicator" lambs were used to establish the level of infection at each rotational grazing cycle. Two generations of parasites were identified in the experiment. One of them, derived from the eggs deposited the previous autumn, gave rise to the first infection of the animals in March and April. This was responsible for the first outbreak of parasitism in the lambs. This was indicated by an increase in serum pepsinogen levels, the appearance of diarrhoea and a significant decrease in lamb growth rates. Ostertagia spp., Nematodirus spp. and Trichostrongylus spp. were present. The second generation, which appeared during May, was derived from the eggs of the previous generation and gave rise to an outbreak of parasitism in the lambs at the beginning of May and the middle of June. Haemonchus spp. and Chabertia ovina were present. Under the conditions of this experiment, the overwintering larvae have an important epidemiological significance as the gastro-intestinal nematodes are one of the main limiting factors for developing intensive sheep production systems.  相似文献   

7.
A longitudinal study of faecal nematode egg counts was made in naturally infected Scottish Blackface sheep over two grazing seasons to 75 weeks of age. Although egg counts were lower in the second grazing season the variation among animals was greater. Egg counts were repeatable from 3 months of age. The repeatability of faecal egg counts within and between grazing seasons was about 0.3. Animals with lower than average egg counts in the first grazing season tended to have lower than average egg counts in the second grazing season. Therefore lambs with relatively low faecal egg counts after 3 months of age are likely to retain their advantage in the following year.  相似文献   

8.
Faecal egg count patterns and clinical signs associated with gastro-intestinal (GI) nematodes of 107 zoo ruminants were monitored at fortnightly intervals for 1 year. The ruminants in this study were kept under different husbandry conditions at two sites of the Royal Zoological Society of Antwerp, the Antwerp Zoo and the Animal Park Planckendael. Artiodactylids involved were Arabian oryx (Oryx leucoryx), scimitar-horned oryx (Oryx dammah), bongos (Tragelaphus euryceros isaaci), sitatungas (Tragelaphus spekii gratus), common eland (Taurotragus oryx), impala (Aepyceros melampus), slender-horned gazelles, (Gazella leptoceros), blue wildebeest (Connochaetes taurinus taurinus), Kordofan giraffes (Giraffe camelopardalis antiquorum) and okapi (Okapia johnstoni). Nematode eggs were recovered from 586 of 1606 (36.5%) individual faecal samples, using flotation techniques. Infection levels were distinctly low at Antwerp Zoo, probably due to zero grazing and daily dung removal. At Planckendael, the herds of Arabian oryx, scimitar-horned oryx and slender-horned gazelles showed markedly higher egg counts than the other herds, with more than 10% of the faecal egg counts having more than 100 eggs per gram (epg) and maximum faecal egg counts of 600, 750 and 1350 epg, respectively. Faecal egg counts increased during the mid-grazing season (July) and peaked at the end of the grazing season (October). No clinical signs, such as loss of faecal consistency, could be correlated with faecal egg counts (P > 0.05). With the exception of significantly more Nematodirus spp. eggs that were present in juvenile eland, no differences in faecal egg counts could be found between the sexes and different age groups. Abomasa and intestines of 17 animals that died during the survey were available for total worm counts. In one Arabian oryx, four slender-horned gazelles and one sitatunga low burdens ranging from 200 to 14,300 were found. Nematode species recovered were Camelostrongylus mentulatus from the abomasa and Trichostrongylus retortaeformis, Nematodirus fillicollis, Capillaria spp. and Trichuris spp. from the intestines. Our findings suggest different nematode infection levels between herds, which are mainly due to husbandry conditions but to a lesser extent to species- or individual susceptibility. Identification of ungulates that are highly infected and knowledge of the seasonal variation of their helminths can contribute greatly to a well-adjusted species-specific management and helminth control program.  相似文献   

9.
Weight gain costs due to infection were higher in sheep than goats, 28 and 17.5%, respectively, for Trichostrongylus colubriformis and 48.7 and 32.2%, respectively, for Haemonchus contortus. The extent of bodyweight cost attributed to anorexia in sheep infected with H. contortus was higher (13.5 g/day) than in sheep infected with T. colubriformis (2.3 g/day). On the other hand, bodyweight cost due to the other pathogenic effects in sheep infected with T. colubriformis were higher (35.6 g/day) compared to sheep infected with H. contortus (10.9 g/day). A strong relationship between faecal egg count and worm count (r=0.79, P=0.006) was shown only in sheep infected with T. colubriformis. About half of the infected sheep and goats had low or zero faecal egg counts throughout the study. In about 40% the egg count rose initially but became low by weeks 10-16, whereas in about 10% counts increased progressively throughout the period of observation and these animals also had the highest numbers of worms at slaughter. Packed cell volume was reduced in sheep and goats infected with H. contortus but serum protein and haemoglobin levels were unaffected. Sheep infected with T. colubriformis had a higher level of eosinophilia after 8 weeks (18.4%) than sheep infected with H. contortus (11.4%), whereas this pattern was reversed in goats and levels were also lower (4.1 and 8.9%, respectively). There was no apparent relationship between eosinophilia and resistance to infection with H. contortus or T. colubriformis.  相似文献   

10.
The anthelmintic activity of thiabendazole (TBZ) at 88 mg kg-1 and ivermectin at 0.2 mg kg-1 was examined in goats with naturally-acquired nematode infections. In one experiment, a herd of 450 does was treated with TBZ or ivermectin at 4-week intervals for 9 months and efficacy was measured by reduction in faecal egg counts after each treatment. In a second experiment, 100 kids were treated with ivermectin and effectiveness measured at 2 and 4 weeks after treatment by comparison of their egg counts with those of nontreated controls. In a third experiment, efficacy of treatment with TBZ and ivermectin was determined by recovery of parasites at necropsy in a controlled test with 15 kids. The results indicated that TBZ generally did not reduce egg counts and only removed 19% of Haemonchus contortus in the controlled test. The efficacy of ivermectin approached 100% for reduction in egg counts and elimination of H. contortus. Species of Ostertagia, Trichostrongylus, Nematodirus and Oesophagostomum also were present in some subjects, but not in sufficient numbers to evaluate effectiveness of treatment.  相似文献   

11.
A study was conducted to evaluate the therapeutic efficacy of doramectin administered intramuscularly at a dose rate of 200 microg/kg to sheep harbouring naturally acquired infections of gastrointestinal nematodes and Oestrus ovis in the southwestern region of France. On day 0, 24 sheep were selected on the basis of positive faecal egg counts (>100 EPG) and positive assessment of O. ovis infection (including positive O. ovis antibody level and positive clinical score). The sheep were randomly allocated to a non-medicated control group (T1) or a doramectin-treated group (T2) of 12 animals each. On day 0, sheep in group T2 received a single intramuscular injection of doramectin (200 microg/kg), whereas those in group T1 received an intramuscular injection of saline solution (sodium chloride, 0.02ml/kg). Individual faecal egg counts were performed on days 0, 1, 2, 3, 4, 5, 6, 7, and 14. Between days 14 and 16, all sheep were slaughtered, and worm and O. ovis burdens were determined. In doramectin-treated sheep, faecal egg counts had decreased to zero by day 4 for all recovered types of nematode eggs: strongyles, Nematodirus sp., Trichuris sp., and Rhabditidae sp. For strongyles, Nematodirus sp., and Rhabditidae, the percentage reductions in faecal egg counts (geometric means) of doramectin-treated sheep, compared to the non-medicated control sheep were 100% from days 4-7. For Trichuris sp., they were 100, 99.7, 99.9, and 100% on days 4, 5, 6, and 7, respectively. On day 14, percentage reductions were 100% for Nematodirus sp. and Rhabditidae, and 99.8 and 99.1% for strongyles and Trichuris sp., respectively. At necropsy, only adult nematodes and mainly first-stage O. ovis larvae were recovered. Doramectin was highly efficacious against the adult stages of Teladorsagia circumcincta (100%), Nematodirus battus (100%), Nematodirus filicollis (99.9%), Oesophagostomum venulosum (99.8%), and Trichuris sp. (99.3%). It was also 100% efficacious against first-stage larvae of O. ovis. No abnormal clinical signs or adverse reactions in any of the sheep treated with doramectin were observed.  相似文献   

12.
The influence of feeding urea-molasses blocks (UMB) on growth and gastrointestinal (GI) nematode parasitism of weaner goats grazing the same pasture was investigated on a farm in Nyandarua District, Kenya. Thirty female Small East African goat kids at an average age of 5 months were initially treated with albendazole orally (5 mg kg(-1) body mass) and randomly assigned into one of two groups: group I were fed UMB prepared using a cold process and group II kids (controls) received no block supplementation (NBS). The UMB were given in the evening when the animals returned from grazing and were consumed during the night at a rate of 95.0 g head(-1) day(-1). Supplementation was undertaken for 3 consecutive months from July to September 2001 and January to March 2002. Body mass of the kids and faecal egg counts were measured monthly and larval cultures were performed on positive faecal samples of kids of each group. Five goats from each group were randomly selected for slaughter and total counts and identification of worms at the end of June 2002. Significant differences (P < 0.05) were found in cumulative mass gains of kids in group I from September compared with those in group II. On termination of the study kids in group I had gained an average of (+/- SD) 20.4 +/- 1.4 kg while those in group II had gained 11.8 +/- 1.1 kg. From January 2002, faecal egg counts of the kids in the UMB group differed significantly (P < 0.05) from those of the NBS group and at slaughter, the mean (+/- SD) worm counts for the UMB group was 482 +/- 299 while that of the NBS group was 1 302 +/- 410. In all the goats, Haemonchus contortus was the predominant nematode recovered. These results indicate that UMB had significant effects in the control of GI nematode parasitism and enhanced growth of the young goats.  相似文献   

13.
A survey was carried out to determine the prevalence and seasonal abundance of the egg and adult stages of nematode parasites of sheep and goats in the semi-arid zone of north-eastern Nigeria between January and December 2002. Faecal samples collected from 102 sheep and 147 goats and examined by the modified McMaster technique using saturated solution of sodium chloride as the floating medium revealed that 44 (43.1%) and 82 (55.8%) of the samples, respectively, contained at least one nematode egg type. Three nematode egg types were recovered with strongyle egg type (22.5% in sheep and 35.4% in goats) being the most prevalent followed, respectively, by Trichuris (5.9% in sheep and 4.1% in goats) and Strongyloides (4.9% in sheep and 4.1% in goats) egg types. Mean faecal egg counts were generally moderate in both sheep (1052+/-922 strongyle, 1000+/-590 Strongyloides and 380+/-110 Trichuris eggs, respectively, per g of faeces) and goats (2092+/-3475 strongyle, 958+/-854 Strongyloides and 683+/-512 Trichuris eggs, respectively, per g of faeces) and showed the same trend irrespective of the age or sex of the animals. The prevalence and counts of strongyle nematode eggs showed a definite seasonal sequence that corresponded with the rainfall pattern in the study area during the period. In both sheep and goats, counts of strongyle egg type increased with the rains and reached peak levels at about the peak of the rainy season in September. The other egg types encountered during the study did not show much variation with the season of the year. Out of the 45 sheep and 75 goats examined at necropsy, 27 (60%) and 39 (52%), respectively, contained adult nematode species. Seven genera of adult nematodes including Strongyloides, Trichostrongylus, Haemonchus, Trichuris, Cooperia, Oesophagostomum and Bunostomum species were encountered during the study. Bunostomum species were recorded only in sheep. Adult worm burdens were generally low and showed seasonal variation that corresponded with the rainfall pattern in the study area during the period. Haemonchus and Trichostrongylus species attained peak counts together in both goats (June) and sheep (August). Strongyloides species were encountered throughout the year in both sheep and goats irrespective of the season. Other genera of nematodes encountered occurred in very low numbers and did not allow any meaningful comparison of seasonal sequence. The results suggest that Haemonchus, Trichostrongylus and Strongyloides species may be the major contributors to small ruminant helminthiasis in the study area.  相似文献   

14.
Haemonchus, Trichostrongylus, Ostertagia and Nematodirus worm populations of Angora goats, based on differential egg counts, are considered in relation to climatological and topographical data. Egg counts indicated that the estimated worm populations in goats that experienced wet circumstances were higher than those exposed to dry conditions. Wetness was assessed by relating spring, summer, and early autumn rainfalls to ground slope. It is proposed, that tactical anthelmintic treatments of goats be based on the degree of wetness of the grazing or property.  相似文献   

15.
A three-year survey (1997-99) was carried out on organically reared sheep flocks throughout Sweden. The aim was to determine the prevalence and intensity of nematode infections and to establish relationships between sheep management practices and parasite infections. Faecal samples from ewes and lambs were collected from 152 organic flocks around lambing-time and during the grazing-period for analysis. Results were compared with the different management practices that farmers use to prevent parasitism in their flocks. A high proportion of the flocks was infected with nematodes. The most prevalent species were Haemonchus contortus, Teladorsagia circumeincta, Trichostrongylus axei. T. colubriformis and Chabertia ovina and infections progressively increased during summer in lambs grazing on permanent pastures. Severity of parasitic infection in lambs was highly dependent on egg output from the ewes. H. contortus was found in 37% of the flocks, even at latitudes approximating the Polar Circle. Nematodirus battus was recorded for the first time in Sweden during the course of this study. Lambs turned out onto permanent pasture showed higher nematode faecal egg counts (epg) than lambs that had grazed on pastures, which had not carried sheep the previous year. This beneficial effect of lambs grazing non-infected pastures persisted if the ewes were treated with an anthelmintic before turn-out and if the lambs were kept on pastures of low infectivity after weaning. In lambs, the prevalence and the magnitude of their egg counts were higher during autumn in flocks where lambs were slaughtered after 8 months of age, compared with flocks where all lambs were slaughtered before this age. These results will be used in providing advice to farmers of ways to modify their flock management in order to minimise the use of anthelmintics, but at the same time efficiently produce prime lambs.  相似文献   

16.
A field investigation was carried out from 1981 to 1983 on the prevalence of Nematodirus battus under different systems of lowland sheep management. Pasture larval counts, ewe and lamb worm egg counts, and tracer lamb worm counts were carried out. As expected, contamination was generally greater on permanent pasture than on new leys as measured by pasture larval counts and lamb worm egg counts. However significant contamination was also recorded on young grass fields for which alternate grazing with young calves may have been partly responsible. It is suggested that the 1983 hatch was delayed because of a drop in soil temperature in late March which may have increased subsequent scour problems involving N battus seen in May.  相似文献   

17.
The purpose of the study was to record and determine intensities, seasonal incidence and distribution of helminth parasites of veterinary importance that occur in cattle, sheep and goats in the northeastern Free State. The study was conducted at Harrismith and Kestell and in Qwa-Qwa from March 2000 to May 2001. Cattle of various breeds (including Bonsmara, Simmentaler and Friesian), Merino sheep and Angora goats were sampled. Faecal samples were analysed using the McMaster and Visser sieve techniques for egg counts and faecal cultures for 3rd-stage nematode larvae identification. Haemonchus and Oesophagostomum were the dominant nematode genera found to be infecting the animals. The socioeconomic status of the farmers in the study area was determined through a questionnaire survey aimed at recording their management strategies. It indicated that 81% of farmers take care of their livestock by feeding them with supplements. The low to moderate faecal egg counts from cattle showed that helminth infections in this region are still under control even though helminthosis seems to be a problem in small-stock, since EPG counts of more than > 1000 were found. Cattle farmers in this region are encouraged to continue with good animal husbandry practices that have ensured that helminth infections rates are kept low. Small-stock farmers are, however, encouraged to control helminth infections in their sheep and goats by anthelmintic treatment.  相似文献   

18.
Composite faecal egg counts (FEC) are increasingly used to support strategic anthelmintic treatment decisions in grazing livestock. However, their accuracy as estimators of group mean FEC is affected by the number of individual samples included, how thoroughly they are mixed, and the underlying degree of parasite aggregation between individual hosts. This paper uses a Negative Binomial model for parasite aggregation, and a Poisson model for egg distribution within faecal suspensions, in order to optimise composite FEC protocol for commercial sheep flocks. Our results suggest that faecal egg density in a well-mixed composite sample from 10 sheep (3g of faeces from each), estimated by examination of four independently filled McMaster chambers, is likely to provide an adequate estimate of group mean FEC in the majority of situations. However, extra care is needed in groups of sheep for which high levels of FEC aggregation might be expected. The implications of statistical error in FEC estimates depend on how they are used. The simulation-based approach presented here is a powerful tool for investigating the risks of error in FEC-driven treatment decisions in different situations, as well as for the statistical analysis of parasitological data in general.  相似文献   

19.
OBJECTIVE: To assess the efficacy of copper oxide wire particles (COWP) for the control of H contortus infections in grazing sheep. PROCEDURE: In experiment 1, 40 worm-free Merino hoggets (11 to 12 months of age) were divided into four equal groups and allocated to separate 0.8 ha pasture plots. Two groups then received 2.5 g COWP whereas the other two groups were untreated. From 1 week after COWP treatment all lambs received a weekly infection of 2000 H contortus larvae. At week 8, six sheep from the untreated group were then allocated to two groups and treated with either 2.5 or 5.0 g of COWP to establish therapeutic efficacy of treatment. Experiment 2 followed a similar protocol but was conducted with 40 worm-free Merino lambs (3 to 4 months of age) and no assessment of therapeutic efficacy was made. Results: In experiment 1 no significant difference in faecal worm egg counts was observed between treatments and faecal worm egg counts remained less than 3000 epg in all animals. Total worm counts were reduced by 37% by COWP treatment (P = 0.055). Both 2.5 g and 5.0 g doses of COWP at 8 weeks of infection reduced faecal worm egg counts by > 85% with the higher dose giving an earlier response to treatment. In experiment 2, faecal worm egg counts at 4 and 6 weeks were reduced by more than 90% in the COWP treated lambs and worm numbers were 54% lower after 6 weeks when all remaining untreated lambs had to be treated for haemonchosis. Mean faecal worm egg counts in the COWP lambs remained below 3500 epg and clinical disease did not develop in the majority of lambs before the end of the experiment at 10 weeks. CONCLUSION: Treatment with COWPs appears to have the potential to reduce establishment and worm fecundity of Haemonchus spp for an extended period and may offer livestock producers a supplementary means of reducing larval contamination of pasture particularly in areas where anthelmintic resistance is a problem and copper supplementation is likely to be beneficial.  相似文献   

20.
Body condition scoring is widely used for sheep and cattle but the practice is included in only one Code of Practice for the welfare of goats in Australia. There is no published scientific evidence to support or defend its use in the assessment of welfare risks to farmed goats. PROCEDURE: The significance of stocking rate, grazing system, body condition score (CS) and live weight were investigated in explaining the risk of mortality of individual and flocks of grazing Angora goats from hypothermia following a severe weather event in April. This event occurred 5 weeks after shearing the goats. Angora goats and Saxon Merino sheep were grazed alone, or mixed together in equal numbers at each of three stocking rates. RESULTS: There was no mortality amongst Angora goats provided they grazed at the lowest stocking rate even when their CS was < or = 2.0. Mortality in flocks of Angora goats was most related to the CS reached during the preceding 2 months. For flocks of Angora goats there was no mortality at CS > or = 2.5 and mortality increased sharply at mean CS < 2.0. For individual Angora goats, mortality increased as CS declined and stocking rate and grazing combinations were additive in effect on mortality. Grazing with sheep increased mortality of Angora goats at higher stocking rates. The individual goat mortality rate was not dependent on individual plot effects suggesting that these results are applicable widely. Live weight loss was not related to mortality rates of goats once CS had been accounted for. CONCLUSION: It was concluded that CS and stocking rate were highly significant determinants of welfare risk in Angora goats.  相似文献   

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