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Control of nematode parasites with reduced reliance on the use of anthelmintics was studied in 16 ewes with suckling twin lambs on contaminated pasture in Denmark. Ewes and lambs were treated with albendazole at turn-out 3 May. Ewes were removed from the groups on 26 July, and lambs were slaughtered on 11 October. The animals were allocated to 4 groups of 8 lambs and their 4 ewes. Group TS was treated with albendazole at weeks 3, 6 and 8 after turnout and set-stocked; group TM was similarly treated but moved to clean pasture in conjunction with the last drenching; group US was untreated and set-stocked, and group UM was left untreated but moved to clean pasture week 8 after turn-out. Supplementary feed was offered in June and August due to scarcity of pasture. Strategic treatments of ewes and lambs weeks 3, 6 and 8 after turn-out, with or without a move to clean pasture, were highly effective in controlling nematode infections for most of the season. This was reflected in better weight gains and carcass characteristics in the treated compared to untreated lambs, resulting in an average increase in the value of the product by 36%. The effect of moving without treatment (UM) on faecal egg counts was limited but peak pasture infectivity was reduced to less than 10% compared to the set-stocked group and weight gains of lambs were significantly better despite poor feed availability in late season. The study showed that under set-stocked conditions repeated anthelmintic treatments of both ewes and lambs in early season may ensure sufficient nematode control whereas moving animals to clean pasture without dosing was less efficient. The latter may, however, still be a viable option in organic and other production systems where routine use of anthelmintics is banned, particularly if weaning and moving are combined or a second move is performed. 相似文献
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Helminth infections are a major cause for reduced productivity in livestock, particularly those owned by the poor worldwide. Phytomedicine has been used for eons by farmers and traditional healers to treat parasitism and improve performance of livestock, and many modern commercial medicines are derived from plants. However, scientific evidence on the anti-parasitic efficacy of most plant products is limited, regardless of their wide ethnoveterinary usage. Scientific validation of the anti-parasitic effects and possible side-effects of plant products in ruminants is necessary prior to their adoption as a novel method for parasite control. A variety of methods has been explored to validate the anthelmintic properties of such plant remedies, both in vivo and in vitro. In vitro assays are useful as pre-screens of activity and are mainly performed with the free-living rather than parasitic stages of nematodes. Concentrations of potentially active substances used in vitro do not always correspond to in vivo bioavailability. Therefore, in vitro assays should always be accompanied by in vivo studies when used to validate the anthelmintic properties of plant remedies. In vivo controlled studies have shown that plant remedies have in most instances resulted in reductions in the level of parasitism much lower than those observed with anthelmintic drugs. Whether it is necessary or not to achieve very high efficacy in order for plant remedies to have a role in the control of parasitism depends on the determination of biologically important levels of reduction of parasitism and it will be required prior to the wide-scale use of plant products for parasite control. Similarly, standardisation of validation studies in reference to the numbers of animals required for in vivo studies to measure direct anthelmintic effects of a plant needs to be established. Although in many cases the active compounds in the herbal remedies have not been fully identified, plant enzymes, such as cysteine proteinases, or secondary metabolites, such as alkaloids, glycosides and tannins have shown dose-dependent anti-parasitic properties. However, as some of the active compounds may also have anti-nutritional effects, such as reduced food intake and performance, it is essential to validate the anti-parasitic effects of plant products in relation to their potential anti-nutritional and other side effects. A concerted effort on isolation, development, and validation of the effects of these herbal remedies will have to be undertaken before their wider acceptance. 相似文献
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Several studies have shown that foot lesions and clinical lameness occur before first calving and develop further during the lactation period. Lameness may cause production losses, but the relationship between foot lesions, particularly in the claw horn, and lameness in heifers is unclear. The objectives of this study were to describe the development of and evaluate the relationship between lameness and foot lesions in Danish Holsteins before and after first calving. In a longitudinal study, 147 heifers were examined for lameness and foot lesions 2–5 times over an 18-month period. Lameness was assessed by means of a visual locomotion score and foot lesion severity was recorded.The prevalence of a locomotion score 3 was 25% before calving, and 90% at approximately 250 days in milk (DIM). Prevalence of moderate to severe sole haemorrhage (SH) was 27% before calving and 56% at 250 DIM, and that of moderate to severe white line lesion (WLL) 44% before calving with a peak of 70% at 200 DIM. There was one case of white line abscess but SH was seen throughout the entire study period. Digital dermatitis (DD) was prevalent prior to first calving (15%) and peaked at 39% at 0–100 DIM. Heel horn erosion (HHE) occurred in almost all cows (93–100%) and was strongly correlated with DD (r = 0.51). The correlation coefficient between SH and WLL was also high (0.42). The relatively high correlations between WLL and both DD and HHE were more surprising (0.38 and 0.35, respectively), those between SH and both DD and HHE were moderate (around 0.18). Interdigital dermatitis was significantly correlated with both HHE and DD, but completely unrelated to SH and WLL.The overall average locomotion score increased by about one-half of a score unit from 1 month prior to calving until 250 DIM, with a large difference between herds, although this was unsurprising as cows may alter their locomotion pattern with management factors (e.g. floor properties). DD and WLL were both associated with a locomotion score 3 but of the cows with severe WLL there was no clear association between a locomotion score 3 and DD. The highest locomotion scores occurred among cows with DD but without WLL. 相似文献
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S S Nielsen H Houe S M Thamsborg V Bitsch 《Journal of veterinary diagnostic investigation》2001,13(2):164-166
Serologic diagnosis of bovine paratuberculosis (Johne's disease) with currently available tests may give false-positive results due to cross-reactions with avian and bovine tuberculosis viruses and other infectious agents. Indirect enzyme-linked immunosorbent assays (ELISA) for detection of antibodies against paratuberculosis based on antigens from Mycobacterium avium subsp. avium (A-ELISA) and M. avium subsp. paratuberculosis (P-ELISA) were compared. Despite an expected higher specificity for M. a. paratuberculosis in the P-ELISA, the 2 antigens were equally suitable for demonstration of antibody to M. a. paratuberculosis in cattle. Receiver operating characteristic (ROC) curves was used to demonstrate the possible antigenic relationship. The area under the curve (AUC) was calculated for each of the 2 ROC curves. The AUC for the P-ELISA ROC curve was 0.9197, and the AUC for the A-ELISA ROC curve was 0.9149, demonstrating a negligible difference in efficiency of the 2 tests (z = 0.182). 相似文献
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Vlaminck J Nejsum P Vangroenweghe F Thamsborg SM Vercruysse J Geldhof P 《Veterinary parasitology》2012,189(2-4):267-273
The significant economical consequences of infections with Ascaris suum in pigs are already well documented. However, due to the subclinical nature of the disease and the lack of practical diagnostic means, ascariasis often remains undiagnosed. Here we describe the development and evaluation of a novel indirect ELISA using the purified A. suum haemoglobin (AsHb) molecule as an antigen. Initial validation using sera from 190 pigs experimentally infected twice a week with A. suum and Trichuris suis (25 and 5eggskg(-1)day(-1) respectively) demonstrated that the AsHb ELISA is able to detect long-term exposure to A. suum with a high sensitivity and specificity (99.5% and 100.0% respectively). Furthermore, this serological technique proved to be more sensitive than faecal examination on week 7 and 14 of the experiment (99.5% and 100% compared to 59.5% and 68.4% respectively). Cross-reactivity caused by T. suis infection was shown to be limited after analysing sera from pigs with an experimental T. suis mono-infection. Seroconversion was shown to occur from week 6 onwards in pigs receiving 100 A. suum eggs 5 times a week. Preliminary testing of the ELISA on six randomly selected farms confirmed the results obtained in the artificial infection trials, showing a higher sensitivity of the serologic method compared to faecal examination. Finally, the ELISA was used to investigate Ascaris infection rates on 101 conventional Flemish pig farms. The results showed that on 38.6% of the farms less than 20% of the tested samples were seropositive, while in 19.8% of the farms 80-100% of all pigs were seropositive. The results of this study suggest that the AsHb ELISA could provide pig farmers and veterinarians with an easier and more sensitive way to estimate the overall prevalence of A. suum on their farm. 相似文献
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Nielsen MK Vidyashankar AN Olsen SN Monrad J Thamsborg SM 《Veterinary parasitology》2012,189(2-4):260-266
Nematodes belonging to the order Strongylida are ubiquitous in grazing horses, and the large strongyle Strongylus vulgaris is considered the most pathogenic. This parasite was originally described widely prevalent in equine establishments, but decades of frequent anthelmintic treatment appears to have reduced the prevalence dramatically. Increasing levels of anthelmintic resistance in cyathostomin parasites have led to implementation of selective therapy to reduce further development of resistance. It has been hypothesized that S. vulgaris could reoccur under these less intensive treatment circumstances. The aim with the present study was to evaluate the occurrence of S. vulgaris and the possible association with usage of selective therapy. A total of 42 horse farms in Denmark were evaluated for the presence of S. vulgaris using individual larval cultures. Farms were either using a selective therapy principle based on regular fecal egg counts from all horses, or they treated strategically without using fecal egg counts. A total of 662 horses were included in the study. Covariate information at the farm and horse level was collected using a questionnaire. The overall prevalence of S. vulgaris was 12.2% at the individual level and 64.3% at the farm level. Farms using selective therapy had horse and farm prevalences of 15.4% and 83.3%, respectively, while the corresponding results for farms not using selective therapy were 7.7% and 38.9%. These findings were found statistically significant at both the horse and the farm level. Stud farms using selective therapy were especially at risk, and occurrence of S. vulgaris was significantly associated with the most recent deworming occurring more than six months prior. The results suggest that a strict interpretation of the selective therapy regimen can be associated with an increased prevalence of S. vulgaris. This suggests that modifications of the parasite control programs could be considered on the studied farms, but it remains unknown to which extent this can be associated with increased health risks for infected horses. 相似文献
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Waruiru RM Thamsborg SM Nansen P Kyvsgaard NC Bogh HO Munyua WK Gathuma JM 《Tropical animal health and production》2001,33(3):173-187
The epidemiology of H. placei and of other gastrointestinal nematodes in yearling dairy cattle was examined on two farms in Kiambu District, central Kenya during each of 13 one-month periods from April 1993 to April 1994. On each farm, 32 newly weaned dairy calves were given a single dose of albendazole and then placed on experimental pastures. Twelve of the animals were designated for bi-monthly slaughter (n = 2) and analysis of worm population characteristics and 20 were designated for blood and faecal collection and for weighing. Two parasite-free tracer calves were grazed alongside the weaner calves each month throughout the study period and were also slaughtered for analysis of worm populations. Faecal egg counts, haematological and serum pepsinogen determinations, herbage larval counts, and animal live weight changes were recorded monthly. The study revealed that Haemonchus placei, Trichostrongylus axei, Cooperia spp. and Oesophagostomum radiatum were responsible for parasitic gastroenteritis and that H. placei was the predominant nematode present in the young cattle on both farms. Faecal egg counts from resident cattle and necropsy worm counts revealed that pasture larval levels were directly related to the amount of rainfall. The total worm burdens in the animals were highest during the rainy season (March–June and October–December) and lowest during the dry seasons (July–September and January–February). The very low recovery of immature larvae of H. placei from the tracer calves indicated that arrested development is not a feature of the life cycle of this parasite in central Kenya. The maintenance of the parasite population depended on continuous cycling of infection between the host and the pasture. The agroclimatic conditions of the study area were such that, in general, favourable weather conditions for the development and survival of the free-living stages of gastrointestinal nematodes existed all year round. 相似文献
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