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1.
The development of gastro-intestinal helminth diversity was monitored in lambs grazing alone or grazing with heifers in the ratio one heifer to four lambs. Five successive cohorts of lambs were studied from January 1994 to May 1996. Each cohort of lambs grazed irrigated pastures of Pangola grass for 4 months (from weaning to 6 months of age). A total of 50 lambs was necropsied and their worms counted and identified at the end of each grazing period. Four heifers were also necropsied on one occasion. Special attention was dedicated to the identification of the most pathogenic worm, i.e. Haemonchus spp. Malate dehydrogenase polymorphism in H. contortus was studied in order to evaluate changes between cohorts and between grazing managements. The species diversity was estimated by Shannon diversity indices (main species or all species). It was higher in the mixed grazing group than in the lambs that grazed alone. Diversity increased in successive cohorts. This was due in part to the acquisition of Cooperia spp. of cattle origin. The increase in diversity in the mixed grazing lambs corresponded to the lower faecal egg excretion and better weight gains recorded previously in that group. There seemed to be no cross-transmission of H. similis found in heifers and H. contortus harboured by lambs. The latter species was not morphologically or genetically different in the lambs grazed alone or with heifers, indicating that the presence of cattle did not modify qualitatively the transmission of H. contortus. 相似文献
2.
Resistance of Teladorsagia circumcincta in goats to ivermectin In 2005, suspected ivermectin resistance of gastrointestinal nematodes was investigated in 17 goats on a farm in the Netherlands, using a faecal egg count reduction test combined with faecal larval cultures. Eight goats were treated orally with 0.2 mg/ kg ivermectin on 1 August 2005 and the other nine goats served as untreated controls. Faeces were collected from all goats on 1 August and on 12 August. Faecal egg counts were reduced by 80.6% in goats receiving ivermectin. On the basis of faecal larval cultures and the egg counts, ivermectin was found to be 100% effective against Haemonchus contortus, 15.0% effective against Teladorsagia circumcincta, and 93.3% effective against Trichostrongylus spp. The effect of levamisole and oxfendazole on gastrointestinal nematodes was also evaluated. Nine goats were treated subcutaneously with 5 mg/kg levamisole and seven goats orally with 4.5 mg/kg oxfendazole on 12 September On the basis of faecal egg counts performed on 12 and 22 September, levamisole reduced the total egg count by 95.4% and oxfendazole reduced the egg count by 85.8%. Differentiation of pooled faecal larval cultures revealed that levamisole was 99.9% effective against H. contortus, 81.9% effective against T. circumcincta, and 99.5% against Trichostrongylus spp. Oxfendazole was 75.5% effective against H. contortus, 33.2% effective against T. circumcincta, and 100% effective against Trichostrongylus spp. On 28 October the nine goats that were still present on the farm were orally treated with 0.4 mg/kg ivermectin. Faecal egg counts and differentiation of pooled larval cultures of faecal samples collected on 28 October and 9 November, respectively, revealed that total egg counts were reduced by 93.1%. Ivermectin was 49.1% effective against T. circumcincta but 100% effective against H. contortus and Trichostrongylus spp. Thus H. contortus appears to be resistant to oxfendazole and T. circumcinta appears to be resistant to oxfendazole and ivermectin. This is the first documented case of ivermectin resistance of a gastrointestinal nematode of small ruminants in the Netherlands. 相似文献
3.
The anthelmintic efficacy of benzimidazoles (albendazole, fenbendazole and oxfendazole), levamisole, oral ivermectin and closantel was evaluated on a farm in Kenya using faecal egg count reduction test, larval cultures and a controlled slaughter trial. The results of this study indicated simultaneous resistance of Haemonchus contortus against benzimidazoles, levamisole and ivermectin, and of Trichostrongylus colubriformis and Oesophagostomum spp. against levamisole on the same farm. Ivermectin resistance developed to 47% within 15 months of first use. Closantel was effective against the benzimidazoles, levamisole and ivermectin resistant H. contortus. 相似文献
4.
Twenty-two Dorset Rambouillet lambs were moved to contaminated pasture on Apr 1, 1987. At regular intervals thereafter, pairs of lambs were withdrawn and euthanatized. Gastrointestinal parasites in the abomasum, small intestine, cecum, and large intestine were removed and counted. The last pair of lambs was euthanatized 8 months after original placement on the contaminated pasture. Fecal samples were taken at 3- to 4-week intervals throughout the grazing season and the fecal egg counts were used to estimate parasite fecundity (output of eggs per female parasite per day). The principal parasite genera found included Haemonchus spp, Trichostrongylus spp, and Nematodirus spp. In each of the genera examined, parasite fecundity remained the same irrespective of the intensity or duration of infection. Estimated average fecundities (eggs/female/day) were as follows: Haemonchus contortus, 6,582; Trichostrongylus spp, 262; Nematodirus spp, 40; and Oesophagostomum venulosum, 11,098. 相似文献
5.
Siedek EM Burden D von Samson-Himmelstjerna G 《Berliner und Münchener tier?rztliche Wochenschrift》2006,119(7-8):303-307
Results of real-time PCR analysis of coproculture third stage larvae (L3) using genus specific TaqMan minor groove binder probes were compared with the results of morphological differentiation of L3 after coprocultured and direct morphological worm differentiation from gastrointestinal samples of eight sheep with naturally acquired nematodes infections. Faecal egg counts prior to postmortem confirmed infections with trichostrongyles with a geometric mean count of 4828 eggs per gram for all sheep. Individual egg counts correlated positively with total worm counts (correlation coefficient 0.794). Five different nematode species and one genus were found in the abomasi and small intestines: Cooperia curticei, Haemonchus contortus, Nematodirus spp., Teladorsagia (Ostertagia) circumcincta, Trichostrongylus axei and Trichostrongylus colubriformis. Coproculture of faecal eggs yielded five of these, Cooperia spp., Haemonchus spp., Ostertagia/Teladorsagia spp. and Trichostrongylus spp. Comparison between morphological L3 and worm differentiation data showed high congruence (94%). The agreement between PCR analysis of L3 after coproculture and direct morphological worm differentiation was 84%. Thus, real-time PCR was found to be suitable as a speedy and reliable diagnostic tool for the assessment of gastrointestinal nematode infections of ruminants in the field. 相似文献
6.
Horak IG 《The Onderstepoort journal of veterinary research》2003,70(3):175-186
At monthly intervals for periods ranging from 9 to 25 consecutive months between three and four Merino yearling-sheep and two Merino lambs on three farms in Eastern Cape Thornveld, and two Dorper yearling-sheep on a farm in Valley Bushveld were slaughtered and examined for helminths. The Merino sheep were infected with 15 nematode species, of which Haemonchus contortus, Nematodirus spathiger and Trichostrongylus spp. were the most numerous, and with four cestode species. The Dorper sheep were infected with 17 nematode species, of which Trichostrongylus rugafus and N. spathiger were the most numerous, and with two cestode species. Haemonchus contortus was most numerous in older sheep during the summer months and exhibited no tendency to over-winter as arrested fourth stage larvae. The largest numbers of N. spathiger were present in sheep on the most coastally located of the farms during autumn and winter; on a farm further inland during spring; and on an inland farm in Valley Bushveld during spring and summer. As Merino lambs progressed from birth to 9 months of age a larger proportion of their dwindling burdens of N. spathiger was present as fourth stage larvae. Dorper sheep in Valley Bushveld harboured most Teladorsagia circumcincta in May and from October to January. Trichostrongylus rugatus was most numerous in Merino sheep on one of the Thornveld farms during September, whereas all Trichostrongylus spp., including T. rugatus, were most numerous in Dorper sheep on the Valley Bushveld farm during January. 相似文献
7.
Three Haemonchus species (Haemonchus contortus, Haemonchus placei and Haemonchus similis) live in sympatry in the savanna of North C?te d'Ivoire. Four domestic ruminant hosts (zebu-cattle, taurine-cattle, sheep and goats) share the same pastures throughout the year. Our post-mortem data imply that a Haemonchus spp. circulation exists among the different hosts species in the savanna of North C?te d'Ivoire. Under field conditions, mixed congeneric infections were the rule except in sheep where mono-specific H. contortus infections were the most frequent. The associations H.contortus+H.placei and H.placei+H.similis were dominant in goats and in cattle, respectively. In the populations examined, triple infections occurred in 11.5% of zebu-cattle and 29% of the taurine-cattle. Considering the intensities of infections, H. contortus was the main Haemonchus species of sheep and goats whereas H. similis was very rare in these host species. About 10% of the worms recovered in goats belong to the H. placei species. In cattle, H. contortus was very rare. H. placei was the dominant species in zebu-cattle (58.7% of the identified worms) and in taurine-cattle (73.9%) nevertheless, the proportion of H. similis was higher in zebu-cattle (38.6%) than in taurine-cattle (21.3%). Only few hybrids between H. placei and H. similis were found. The importance of such Haemonchus spp. circulation is discussed. 相似文献
8.
Studies on the epidemiology of gastrointestinal nematodes of sheep, conducted at two different farms in the Baghdad area, in 1979, revealed two peaks in worm egg counts in ewes, one in spring and the other in autumn; the latter coincided with the lambing season. Similarly in lambs, two peaks of infection were apparent, but the spring peak was not so well defined. During the hot and dry summer months of Iraq, helminthic infection was at a low level. Faecal culture for larvae and their identification indicated the predominance of Haemonchus contortus infection in the ewes and that of Ostertagia and Trichostrongylus spp. in the lambs examined, Trichostrongylus infection predominating during the hot, dry period of the year. The self-cure phenomenon as well as preparturient rise in egg counts, as reported in other countries, was also observed during this study. 相似文献
9.
Faecal samples (n=1155) were collected from n=111 (Farm A) and n=124 (Farm B) 2-6 week old female lambs on two farms in southern Western Australia across five sampling occasions (spanning 8 months). Genomic DNA was extracted directly from faecal samples and screened by PCR for ITS-2 nuclear ribosomal DNA to detect patent strongylid infections, specifically Teladorsagia circumcincta, Trichostrongylus spp., Haemonchus contortus, Oesophagostomum spp. and Chabertia ovina. The minimum amount of extracted genomic DNA necessary for successful PCR amplification was 2.0-5.0 pg. During the five sampling occasions for the two farms, the sensitivities for WEC and PCR identification of strongylid infections varied, with levels of agreement between the two sets of diagnostic results ranging from 85 to 100%. Strongylid species prevalences were high (90.3-97.3%), with T. circumcincta and Trichostrongylus spp. the most prevalent species and together they were the most common mixed strongylid infection; H. contortus was not identified in either flock. T. circumcincta was the only species associated with an increased risk of non-pelleted faeces on Farm B, where T. circumcincta-positive lambs were 2.3 and 2.6 times more likely to have non-pelleted faeces than negative lambs at the second and final samplings, respectively. The highest strongylid prevalence, mixed strongylid prevalence and mean number of strongylid species detected per lamb coincided with the highest average flock faecal worm egg counts (WECs) on both farms. There was a positive correlation between the number of strongyle species detected per lamb and both WEC and adjusted WEC (P<0.01; r(2) 0.026-0.591). These results indicate that strongylid eggs were likely to be the main source of strongylid DNA in the faecal DNA extracts. Despite the progress made by the molecular approach utilised in this study, it is incapable of distinguishing between patent and non-patent sources of strongylid DNA. However there is potential for further investigation into the development of a similar molecular procedure which could be used for early larvae detection on pastures. 相似文献
10.
用Ｒｉｎｔａｌ片进行了驱除绵羊消化道线虫试验。结果表明当５ｍｇ／ｋｇ体重剂量时对捻转血矛线虫、哥伦比亚线虫、羊仰口线虫、细预属线虫和奥斯特线虫等绵羊消化道线虫的虫卵减少率，虫卵转阴率、虫卵孵化第三期幼虫减少率和第三期幼虫转阴率均可达到１００％，且安全，无任何毒副作用。 相似文献
11.
Genetic resistance to gastrointestinal nematode parasites in Rh?n sheep following natural infection.
Genetic parameters of resistance to gastrointestinal nematodes were estimated in Rh?n sheep, a local sheep breed in Germany. In the first year, a total of 131 lambs (born between January and February 1998) from five rams were evaluated. Faecal egg counts (FEC) (n=1528) were measured in all lambs every 2 weeks until 4 months of age and every 4 weeks until 12 months of age in female lambs. In the second year, a total of 129 lambs (born between January and February 1999) from the same rams were evaluated. FEC (n=645) were measured in the lambs every 4 weeks until 5 months of age. Blood was taken in both years at the time of faecal sampling from the jugular vein and haematocrit was measured. Heritabilities for log(10)(FEC+25) were between 0.11 and 0.44. Heritabilities for the corresponding haematocrits were between 0.19 and 0.26 depending on the number of samples taken in account. A significant negative correlation was estimated for the parameters of FEC and daily weight gain (r=-0.57). The results confirm the feasibility of genetic selection in Rh?n sheep for resistance to nematode parasites in an environment where Trichostrongylus spp./Teladorsagia spp., Haemonchus contortus and Cooperia spp. are the dominant species. Breeding decisions can be based on one or two samples depending on the mean values and ranges of FEC and haematocrit, respectively. 相似文献
12.
Invasions of gastrointestinal nematodes proved to be the most frequent helminthiases in new-established large-capacity herds of cattle according to the results of parasitary examinations of cattle in one locality in the Tachov district. The nematodes, especially Oesophagostomum spp., Haemonchus contortus, Cooperia spp., Trichostrongylus spp., occurred in animals of all age categories. The Ostertagia spp., Chabertia ovina, Nematodirus spp., Bunostomum phlebotomum and Trishuris spp. participated in the invasions to a smaller extent. The first eggs can already be found in three months old calves. Strongyloidosis can be diagnosed in the first month of age in calves [5%], the incidence rate increasing up to the age of five months, then it begins to decrease. Taenasis was found out in six months old calves [4.4% and11.6%]. Reclamations of pastures reduced the incidence of fasciolosis to the minimum rate; its invasions were heavy before establishing the large-capacity herds of cattle. Dictyocaulosis was not found in the large-capacity herds of cattle at all, due to the same reasons. Not only were nematode eggs proved, but also larvae to develop to the stages capable of invasion [Chabertia ovina, Haemonchus contortus, Oesophagostomum spp., Strongyloides papillosus] in dry excrements on railings of pens, on slatted floors and walls of the calf-sheds that were investigated. 相似文献
13.
Evaluation of anthelmintic effects of Trianthema (T.) portulacastrum L. (Aizoaceae) whole plant and Musa (M.) paradisiaca L. (Musaceae) leaves against prevalent gastrointestinal worms of sheep was done that may justify their traditional use in veterinary clinical medicine. In vitro anthelmintic activity of the crude aqueous methanolic extract (CAME) of both the plants was determined using mature female Haemonchus (H.) contortus and their eggs in adult motility assay (AMA) and egg hatch test (EHT), respectively. In vivo anthelmintic activity of crude powder (CP) and CAME in increasing doses (1.0-8.0 g kg(-1)) was determined in sheep naturally infected with mixed species of nematodes using fecal egg count reduction test (FECRT) and larval counts. The study design also included untreated as well as treated controls. Fecal egg count reduction and larval counts from coprocultures were performed pre- and post-treatments to assess the anthelmintic activity of the plants. CAME of T. portulacastrum and M. paradisiaca showed a strong in vitro anthelmintic activity and pronounced inhibitory effects on H. contortus egg hatching as observed through AMA and EHT, respectively. Both plants exhibited dose and time dependent anthelmintic effects on live worms as well as egg hatching. M. paradisiaca (LC(50)=2.13 μg mL(-1)) was found to be more potent than T. portulacastrum (LC(50)=2.41 μg mL(-1)) in EHT. However, in vivo, maximum reduction in eggs per gram (EPG) of faeces was recorded as 85.6% and 80.7% with CAME of T. portulacastrum and M. paradisiaca at 8.0 g kg(-1) on 15th day post-treatment, respectively as compared to that of Levamisole (7.5 mg kg(-1)) that caused 97.0% reduction in EPG. All the species of gastrointestinal nematodes (GINs), i.e. Haemonchus contortus, Trichostronglyus spp., Oesophagostomum columbianum and Trichuris ovis which were prevalent, found susceptible (P<0.01) to the different doses of CP and CAME of both plants. The data showed that both T. portulacastrum and M. paradisiaca possess strong anthelmintic activity in vitro and in vivo, thus, justifying their use in the traditional medicine system of Pakistan. 相似文献
14.
DB ADAMS JJ LYNCH† BH ANDERSON LR FELL‡ GN HINCH§ RK MUNRO¶ 《Australian veterinary journal》1990,67(12):443-445
Three-year-old, non-lactating and non-pregnant Merino ewes, raised on pasture under a program of strategic treatment with anthelmintic and found to be extremely resistant to "trickle" infection with Haemonchus contortus, were given single-dose infections with either H. contortus or Trichostrongylus colubriformis or both species together. The purpose was to ascertain the intensity of protective immunity against the 2 parasites in sheep with immunity acquired from a presumably slight exposure to infection. To provide a criterion, some infected ewes were immunosuppressed with corticosteroid, dexamethasone. Untreated ewes were extremely resistant to challenge infection with either 15,000 or 150,000 H. contortus or 15,000 T. colubriformis. Surprisingly, when mixed infection was given, egg counts for H. contortus were significantly elevated compared with infection by that species alone. Antibody to antigens from infective larval and adult H. contortus was measured in serum by enzyme-linked-immunosorbent assay (ELISA) during the course of infection. Serum titres against larval antigens were significantly depressed when infections with either H. contortus or T. colubriformis were permitted by immunosuppression with dexamethasone, whereas those against adult antigen were depressed when infection with T. colubriformis was permitted. 相似文献
15.
High genetic correlation between resistance to Haemonchus contortus and to Trichostrongylus colubriformis in INRA 401 sheep 总被引：1，自引：0，他引：1
To compare the protection acquired by infection with Haemonchus contortus or Trichostrongylus colubriformis, successive cross infections with the two species were conducted in two genetically similar groups of 150 ewe lambs from 30 sires of INRA 401 breed. At 6 and 7.5 months of age, each group received two doses of 10000 L3 separated by a treatment of one of the species, followed by a similar infection with the second species at 9 and 11.5 months. Faecal egg counts (FECs) were done 28 and 35 days after each dose. There were very high genetic correlation within and between species suggesting that the environmental conditions were very similar. The heritability of FEC of H. contortus ranged from 0.39 to 0.48 and the genetic correlations between FEC after the first and second infections with the same or different species were all near 1. Selection against this species could be done on the response to only one dose. For T. colubriformis, only the response to challenge infection had a similar heritability (0.47); the genetic correlations within and among species were also near one. These results will assist the selection of sheep resistant to nematode parasites. 相似文献
16.
J H Boersema F H Borgsteede M Eysker W M Hendrikx J Jansen C M Smith-Buys 《Research in veterinary science》1987,43(1):18-21
A survey was carried out in The Netherlands to determine the prevalence of benzimidazole resistance in sheep nematodes. It was shown that 47 per cent of the 59 investigated flocks harboured trichostrongylid populations with resistance to benzimidazoles, as demonstrated by an LD50 value of 0.12 micrograms ml-1 thiabendazole or higher in an in vitro egg hatch assay. On these farms Haemonchus contortus was found to be the dominant species. In two flocks resistant Ostertagia and, or, Trichostrongylus species populations were found. Farms with resistance were revisited to determine the anthelmintic efficacy in vivo by means of treatment and egg count. In only four of the 19 flocks which showed resistance in vitro was an efficacy of less than 95 per cent in vivo achieved. This means that there is a discrepancy between the in vivo and in vitro results. Resistance was found more frequently on pure sheep farms than on mixed farms. It is suggested that mixed farms offer more refuge for susceptible H contortus populations. 相似文献
17.
Bambou JC Archimède H Arquet R Mahieu M Alexandre G González-Garcia E Mandonnet N 《Veterinary parasitology》2011,178(3-4):279-285
The aim of the present study was to test the effect of dietary supplementation on resistance to experimental infection with Haemonchus contortus in Creole kids. One trial with three replicates involved a total of 154 female kids that were chosen from three successive cohorts of the Creole flock of INRA-Gardel in 2007. The kids were placed into four treatments according to the amount of concentrate they received: G0 (no concentrate and a quality Dichantium spp. hay ad libitum, HAY), G1 (HAY+100g commercial concentrate d(-1)), G2 (HAY+200 g commercial concentrate d(-1)), G3 (HAY+300 g commercial concentrate d(-1)). The G0-G3 groups were infected with a single dose of 10,000 H. contortus third stage larvae (L(3)) at Day 0 (D0). Each infected group was comprised of one half resistant and one half susceptible genetically indexed kids. The average breeding values on egg excretion at 11 months of age were distant of 0.70, 0.65, 0.61 and 0.61 genetic standard deviations in G0, G1, G2 and G3, respectively. The faecal egg count (FEC), packed cell volume (PCV), eosinophilia (EOSI) and dry matter intake (DMI) indices were monitored weekly until 42 days post-infection. Enzyme-linked immunosorbent assay was carried out on serum samples to determine the level of IgA anti-H. contortus L(3) crude extracts and adult excretion/secretion products (ESP). The 10,000 L(3) dose received by the kids induced a severe infection: 8000 eggs per gram at the FEC peak, a PCV less than 15% and mortality. Interestingly, the supplemented animals in G3 showed a higher level of EOSI but a lower level of IgA anti-L3 and IgA anti-ESP than non-supplemented animals (G0). Resistant and susceptible kids had significantly different FEC variations within the groups. Susceptible kids had a 1.6 times higher egg output than resistant kids in G0. This difference was not found in the supplemented groups. The results of this study showed that supplementary feeding improved resistance of Creole kids to H. contortus experimental infection. 相似文献
18.
The prevalence and level of thiabendazole resistance of sheep nematodes in the North Island of New Zealand was investigated by means of an in vitro egg-hatch technique; samples from sheep on 52 properties in six country areas were examined. Resistance of Haemonchus contortus and Trichostrongylus spp. was identified on the basis of egg hatch in 0.1 ppm thiabendazole. Evidence of resistance was obtained on 11(21.2%) of the properties. LD 50's and resistance ratios were calculated for the resistant nematode populations found. 相似文献
19.
L. Ayalew J. L. Frchette R. Malo C. Beauregard 《Canadian journal of veterinary research》1973,37(4):356-361
Nematode populations is stabled ewes of the Rimouski region were studied by means of fecal worm egg counts, fecal culture of larvae, and worm counts at necropsy. It was found that during the winter strongyle egg counts were low, Trichostrongylus eggs being most numerous, The stronglye egg counts increased following lambing and reached peak in June. Ostertagia spp was the principal contributor to this “spring-rise”, with substantial contribution from Trichostrongylus and Haemonchus contortus. The bulk of adult worm populations in winter, however, was made up of Trichostrongylus, whereas the great majority of the populations of Ostertagia spp, H. contortus and Nematodirus spp were inhibited in development at the fourth larval stage. All the worms recovered at necropsy in spring were adults, coinciding with the “spring-rise”. 相似文献
20.
Groups of four stag fawns, weighing 51 +/- 0.8 kg, were-infected with 30,000 larvae of one of three nematode parasites: O.circumcincta, O.ostertagia, or H.contortus. A further four remained as control. Individual feed intake, body-weight, faecal egg count and plasma pepsinogen concentration were measured during seven weeks after infection. Only infection with H.contortus caused significant elevation of pepsinogen concentration to 380ml/ L and consistent depression of feed intake (15%). Worm egg counts were below 300 e.p.g. in deer infected with all worm species. It is concluded that while resistance to development of parasites common to other species appears to be high further investigation of the susceptibility of deer to H. contortus infection would be justifiable. 相似文献