Mean Faecal Egg Counts Research Articles

Experiences with Duddingtonia flagrans administration to parasitized small ruminants

The aim of this study was to investigate the effect of the nematophagous fungus Duddingtonia flagrans applied orally to small ruminants in a field study in Germany. 20 female, pure breed goat kids and 20 female, pure breed lambs, all naturally infected with GIN, were kept on pasture and fed additionally with concentrates amended by 5 × 10 5 spores of D. flagrans per kilogram bodyweight daily for 3 months during pasture season. The equally sized control groups got the concentrate without spores. Every fortnight data of body weight, eggs per gram faeces and larval development in faecal cultures and on pasture were collected. Following 3 months of spore feeding the control goats showed arithmetic mean faecal egg counts of 1235 (±533) eggs per gram (epg) faeces, in comparison to 517 (±671) epg in the fungus-fed group ( p < 0.001). No statistically significant difference was found between the two sheep groups. The maximum in larval reduction in faeces was found at the end of the fungus-feeding period (81.3% in the sheep groups and to 67.9% in the goat groups), but without statistical significance. At the end of the study the mean body weight gain in the fungus-treated groups tended to be higher than in the control groups, but not showing statistically significant differences. Only regarding the first-year-grazing-goats, the bodyweights of the post-feeding period revealed significant ( p < 0.05) differences between fungus-fed and control group. However, no statistically significant differences were observed in qualitative faecal cultures, pasture larvae counts, serum pepsinogen-level and PCV. In the study presented here, no clear effect of fungus could be observed. Furthermore, climatic conditions during the study period may have demonstrated how vulnerable the fungus application is to such parameters.

Comparative experimental Haemonchus contortus infection of two sheep breeds native to the Canary Islands

This study compares the susceptibility to Haemonchus contortus infection in two breeds of sheep endemic to the Canary Islands, the Canaria Hair Breed sheep and the Canaria sheep. Sheep were experimentally infected with 20,000 larvae of H. contortus and animals killed on days 7 and 28 post-infection. No difference between sheep breeds were detected in immature worm counts at days 7 or 28 post-infection. However, in comparison to the Canaria sheep breed, the Canaria Hair Breed sheep showed lower mean faecal egg counts, lower adult worm counts, lower number of eggs in utero and female worm stunting. Overall, these data suggest that the Canaria Hair Breed sheep has a greater resistance to H. contortus infection than Canaria sheep, and that this resistance may act at the level of the adult parasite.

Effect of rainfall and temperature on liver and rumen fluke infestations of bovines in Sri Lanka

Fecal fluke egg output of bovines from three selected farms at Ma Eliya (site A), Ma Eliya (site B) and Delathure (site C) in Ja-Ela area of Gampaha district in Sri Lanka was examined for six months period from July to December 2006. The mean egg output of the animals of site A, B and C were 255, 84 and 95 eggs/g of feces respectively. Statistical analysis showed that mean fecal fluke egg output was significantly different between sites (df= 2, f= 126.05, p=0.000) and also between months (df= 5, f= 7.31, p=0.000). Regression analysis revealed that the fecal fluke egg output had a positive relation with rainfall (r2=0.6178) and a negative relation with temperature (r2= 0.6486). The female cattle had a higher fecal fluke egg output (x =202.76) than the male cattle (x =116.97) but egg output did not significantly differ. Also there was an increasing trend of mean fecal fluke egg count with the increment in the age of cattle (r2= 0.6057). Rumens and livers of slaughtered cattle and buffaloes from the study area were examined for fluke infections. Specimens were identified by making histological sections. One species of liver fluke, Explanatum explanatum and four rumen flukes, Paramphistomum spp., Gastrothylax crumenifer, Carmyerius spp., and Fischoederius elongates were identified. Two other flukes belonging to the family Gastrothylacidae were also found from the rumen of buffalo. Explanatum explanatum was found to be a great cause of condemnation of livers at slaughterhouses in Sri Lanka. Keywords: liver and rumen flukes, bovines, influence of climate, Sri Lanka. International Journal of Biological and Chemical Sciences Vol. 1 (3) 2007: pp. 229-236

Efficacy of the nematode-trapping fungusDuddingtonia flagransagainst infections byHaemonchusandTrichostrongylusspecies in lambs at pasture

The efficacy of the nematode-trapping fungus Duddingtonia flagrans against infections by trichostrongyle nematodes in sheep was assessed throughout 6 months. Twenty Ile de France lambs were divided into two groups (control and treated groups), which were kept in separate pastures. Animals of the treated group were fed with D. flagrans twice a week (Tuesdays and Fridays). Pellets were prepared with the fungus mycelia in liquid culture medium and contained approximately 20% fungus. They were mixed with the animals' diet at a concentration of 1 g pellet per 10 kg live weight. Faecal egg counts (FEC), packed cell volume (PCV), total serum protein and the animals' body weight were determined fortnightly from 7 October 2005 to 24 March 2006. Comparison of such parameters between groups showed no significant differences (P > 0.05), except on 10 February 2006, when the control group presented a higher mean FEC than the treated group (P < 0.05). Feeding sheep with pellets containing D. flagrans had no benefit to the prophylaxis of nematode infections under the experimental conditions used in the present study.

The efficacy of Ivermectin and Levamisole against natural Nematodirus spathiger infection in the Arabian sand gazelle ( Gazella subgutturosa marica) and the Arabian mountain gazelle ( Gazella gazella) in Saudi Arabia

The efficacy of two broad spectrum anthelmintics (Ivermectin and Levamisole) against the nematode Nematodirus spathiger in the reem (Arabian sand gazelle) and idmi (Arabian mountain gazelle) at King Khalid Wildlife Research Centre (KKWRC) was determined. Gazelles of both species naturally infected with N. spathiger were each divided into 3 groups. One group was treated with Ivermectin, the other group with Levamisole and the last group was left as untreated control. Faecal egg counts were employed to determine the efficacy of the two drugs against N. spathiger infection in both gazelle species. Reduction in arithmetic mean faecal egg counts achieved by Ivermectin and Levamisole in the reem gazelles was 94% and 89.3%, respectively. The reduction in the idmi gazelles was 97.2% and 96.4%, respectively. Hence, both anthelmintics appeared to be more effective in the idmi gazelles than in the reem gazelles, however, there was no significant difference in the faecal egg reduction tests in both animal species.

The use of age-clustered pooled faecal samples for monitoring worm control in horses

A study was performed on two horse farms to evaluate the use of age-clustered pooled faecal samples for monitoring worm control in horses. In total 109 horses, 57 on farm A and 52 on farm B, were monitored at weekly intervals between 6 and 14 weeks after ivermectin treatment. This was performed through pooled faecal samples of pools of up to 10 horses of the groups ‘yearlings’ (both farms), ‘2-year-old’ (two pools in farm A), ‘3-year-old’ (farm A) and adult horses (four pools on farm A and five pools on farm B), which were compared with the mean individual faecal egg counts of the same pools. A very high correlation between the faecal egg counts in pooled samples and the mean faecal egg counts was seen and also between the faecal egg counts in pooled samples and larval counts from pooled faecal larval cultures. Faecal egg counts increased more rapidly in yearlings and 2-year-old horses than in older horses. This implied that in these groups of young animals faecal egg counts of more than 200 EPG were reached at or just after the egg reappearance period (ERP) of 8 weeks that is usually indicated for ivermectin. This probably means that, certainly under intensive conditions, repeated treatment at this ERP is warranted in these young animals, with or without monitoring through faecal examination. A different situation is seen in adult animals. Based on the mean faecal egg counts on both farms and on the results of pooled samples in farm A, using 100 EPG as threshold, no justification for treatment was seen throughout the experimental period. However, on farm B values of 100 EPG were seen at 9 and 11, 13 and 14 and 14 weeks after ivermectin treatment in pools 10, 12 and 13, respectively. This coincided with the presence of one or two horses with egg counts above 200 EPG. The conclusion is that random pooled faecal samples of 10 adult horses from a larger herd, starting at the ERP and repeating it at, for instance, 4-week intervals, could be used for decisions on worm control. However, there would be a certain risk for underestimating pasture contamination through missing high-egg excreters. An alternative use of pooled samples would be as a cheap first screening to detect which adult horses really contribute to pasture contamination with worm eggs on a farm. All horses should be sampled and subsequently animals from ‘positive’ pools can be reexamined individually.

Effect of tanniniferous browse meal on nematode faecal egg counts and internal parasite burdens in sheep and goats

The effect of tanniniferous browse meal on faecal egg counts (FEC) and intestinal worm burdens was investigated in sheep and goats infested experimentally with gastrointestinal nematodes. Initially, leaves of different browse tree species were assayed for condensed tannin (CT) content using a colorimetric method to determine concentration and seasonal variations. The level of CT in the leaves ranged between 58 – 283 g/kg dry matter. Seasonal changes in CT levels were influenced by stage of leaf maturity with peak levels after the wet season in June. Leaves of Acacia polyacantha had the highest tannin concentration and were used to test their anthelmintic effect in goats and sheep infested with the nematodes in two separate feeding trials. In Trial 1 an acacia leaf meal supplement (AMS) was offered at 100 – 130 g/animal/day for 20 days to growing Small East African goats to investigate its effect on FEC and worm burden. Mean FEC and worm burden of the AMS-fed group were respectively 27% and 13% lower than in the control group. Trial 2 was similar to Trial 1 except that AMS was offered for 30 days to growing Black Head Persian sheep at 170 g/animal/day. The sheep receiving AMS showed a slight reduction in FEC (on average 19% lower than the control group) but had no effect on worm burden. The current results substantiated previous reports of a suppressing effect of CT on gastrointestinal nematodes of small ruminants. Although the observed anthelmintic activity of AMS was less than expected, such reductions can have practical epidemiological implications in reducing pasture larval contamination. Further studies are needed under field conditions to evaluate the feasibility of using locally available tanniniferous browse as an alternative to synthetic anthelmintics in reducing worm infestations in small ruminants. South African Journal of Animal Science Vol. 37 (2) 2007: pp. 97-106

First report of multiple drug resistance in trichostrongyles affecting sheep under field conditions in Italy

Drug resistance in sheep gastrointestinal trichostrongyles is a cosmopolitan major constraint to small ruminant production. Despite reports that anthelmintic drug resistance has become common, there are limited information on the presence of drug resistance in Italy. The purpose of this study was to determine the effect of four anthelmintics to control infection in sheep in central Italy. Fifty sheep with fecal egg counts (FEC) > or =150 eggs per gram were selected on each of three farms (n = 150 total sheep) which were randomly allocated to one of five groups. Groups were treated with febantel, levamisole, ivermectin, or moxidectin while the fifth group acted as the control group. A FEC reduction test (FECRT) was conducted on each animal and the mean FEC of each treatment group was compared to that of the control group within farm. Resistance was declared when percentage reduction (R) <95% and the lower 95% confidence interval was <90%. Levamisole (mean R = 89%) resistance was found on all farms and ivermectin (mean R = 93%) resistance was found on two of the three farms. Posttreatment larval cultures showed the presence of Teladorsagia (Ostertagia) circumcincta and Trichostrongylus spp. larvae. Febantel (mean R = 96%) and moxidectin (mean R = 100%) remained effective. This study suggests that drug resistance in sheep gastrointestinal trichostrongyles is present in central Italy and a potential problem which would justify a broader nationwide geographical investigation.

Dynamics of infections with gastrointestinal parasites and Dictyocaulus viviparus in dairy and beef cattle from Costa Rica

A longitudinal survey was carried out to determine and describe the prevalence and intensity of gastrointestinal parasite infections and Dictyocaulus viviparus in a dairy and a beef cattle farm of two different ecological zones in Costa Rica. The influence of anthelmintic treatment, age and meteorological factors (rainfall, minimum and maximum temperatures) on gastrointestinal nematodes and D. viviparus counts was determined. Calves were subjected to monthly sampling of feces and blood between April 2002 and March 2003. Coprological techniques were used to detect gastrointestinal helminthes, protozoan and D. viviparus. Blood samples were analyzed for antibodies to D. viviparus by ELISA. The most prevalent gastrointestinal parasites detected on both farms (dairy cattle, A; beef cattle, B) were Eimeria spp. (94.7%, 93.7%), Strongylidae (75.0%, 81.4%), Buxtonella sulcata (38.0%, 21.6%) and Strongyloides papillosus (29.8%, 31.7%), whereas Moniezia benedeni (4.8%, 9.1%), Trichuris spp. (7.3%, 13.2%), Toxocara vitulorum (0.0%, 1.8%) and Entamoeba bovis (2.5%, 1.1%) were less prevalent. Mean fecal egg counts (FEC) showed highest values of Strongylidae in April, May and July (>335.3 eggs/g feces) on farm A, and April, May and August (>304.3 eggs/g feces) on farm B. S. papillosus presented low FEC throughout the year on farm A, on farm B the highest values were obtained in April (303.0 eggs/g feces). Trichuris spp. presented maximum FEC values in May (328.6 eggs/g feces) on farm A and in June (157.5 eggs/g feces) on farm B. Treatment and age had significant influence on infection intensity of Strongylidae (farms A and B), S. papillosus (farms A and B) and Trichuris spp. (farm A). Rainfall had significant effect on S. papillosus (farms A and B) and Trichuris spp. (farm B). Maximum temperature showed significant effect on S. papillosus (farm A) and Trichuris spp. (farms A and B). Minimum temperature had significant influence on Strongylidae (farm A), S. papillosus (farms A and B) and Trichuris spp. (farm B). Haemonchus spp. (57%, 66%) and Cooperia spp. (30.0%, 30.7%) were the most prevalent genera identified by coproculture on both farms, in contrast, Trichostrongylus spp. and Oesophagostomum spp. were less frequent. Patent lungworm infections were low on both farms (10.8%, 1.8%). On farm A, high prevalence of antibodies against D. viviparus was determined only at the beginning of the study, in contrast, on farm B the seroprevalence fluctuated throughout the year. Treatment, age and maximum temperature had significant effect on D. viviparus counts on farm A, but not on farm B.

Anthelmintic resistance in cattle nematodes in northwestern São Paulo State, Brazil

The present study was carried out in the northwestern region of São Paulo State, Brazil, to determine the anthelmintic resistance status in cattle naturally infected with gastrointestinal nematodes. The anthelmintics tested were levamisole phosphate (Ripercol ®, Fort Dodge), albendazole sulphoxide (Ricobendazole, Fort Dodge), ivermectin (Ivomec ®, Merial) and moxidectin (Cydectin ®, Fort Dodge), administered at the doses recommended by the manufacturers. From April 2002 to May 2004, 25 cattle farms were evaluated. On each farm, steers were divided into treatment and control (not treated) groups based on fecal egg counts (FEC). Between 7 and 10 days after the anthelmintics administration, fecal samples were collected from each animal for post-treatment FEC. Fecal cultures from each group were also prepared for larval identification. After treatment, mean FEC reduction (FECR) in treatment groups (compared with control groups) was assessed on each farm. FECR was lower than 90% on 23 farms after ivermectin treatment. On 19 farms, FECR of 100% was recorded following moxidectin treatment; on the remaining 6, FECR ranged from 90% to 97.2%. After albendazole treatment, FECR was higher than 90% on 20 farms and ranged from 47.4% to 84.6% on other 5. After levamisole treatment, FECR was higher than 90% on 23 farms and equal to 47.4% and 73.7% on other 2 farms. Results indicated the presence of resistant Cooperia spp. and Haemonchus spp., especially to ivermectin; on some farms, resistance to albendazole and levamisole was also observed.

Use of copper oxide wire particles to control gastrointestinal nematodes in goats1

The objectives of these experiments were to determine the optimal dose of copper oxide wire particles (COWP) necessary to reduce gastrointestinal nematode (GIN) infection in young and mature goats naturally infected with Haemonchus contortus or a mixed infection and to determine whether the effectiveness could be enhanced through feeding management. Two experiments were conducted during cooler months in Georgia, and 4 experiments were conducted during warmer spring or summer months in Arkansas. Meat goats received 0 up to 10 g of COWP under a variety of management conditions. In all experiments, blood and feces were collected every 3 or 7 d from 6 to 42 d to determine blood packed cell volume (PCV) and fecal egg counts (FEC) to estimate the degree of GIN infection. In mature goats grazing fall pasture, mean FEC of 0 g of COWP-treated goats increased, and those of 4 g of COWP-treated goats remained low on d 0, 7, and 14 (COWP x d, P < 0.03), and FEC decreased on these days (P < 0.001). In 5 and 10 g of COWP-treated goats, PCV increased (P < 0.001), but FEC and PCV remained unchanged over time in control goats. Fecal egg counts were similar among all low doses (0.5, 1, 2, 4 g) of COWP administered to weaned kids for all dates examined (P > 0.10), which were lower on d 7 through 21 (COWP x date, P < 0.05) but similar by d 28, compared with FEC of 0 g of COWP-treated kids. Packed cell volume was lower in 0 g compared with all COWP-treated kids by d 14 (COWP x date, P < 0.05). Feeding management in combination with COWP for GIN control had little effect compared with COWP alone for these short-term studies. In conclusion, a dose of COWP as low as 0.5 g, which was considered optimal to reduce the risk of copper toxicity, was effective in reducing FEC in young goats, and 5 g of COWP was effective in older goats. Copper oxide does not appear to be effective in controlling newly acquired L4 stage (preadult) larvae, which also feed on blood, leading to decreased PCV in newly infected goats.

Preliminary investigations of the anti-nematode activity of Acacia cyanophylla Lindl.: Excretion of gastrointestinal nematode eggs in lambs browsing A. cyanophylla with and without PEG or grazing native grass

The potential use of Acacia cyanophylla Lindl. (acacia), a tanniniferous shrub species, as a biologic way to reduce gastro-intestinal parasites was examined in grazing Barbarine lambs. Three groups each of 10 lambs were allocated to one of the following dietary treatment according to a cross-over design: grazing native pasture free of acacia and other woody species (grass group), grazing acacia (acacia group), and grazing acacia after daily oral administration of 40 g polyethylene glycol (PEG mol. weight 4000) (acacia plus PEG-group). PEG, a potent deactivating agent for condensed tannins, was mixed in water (1 kg in 2 l of water) and administered orally. Animals received daily at 8:30 h 300 g concentrate, and were then allowed to graze in the pasture or in the acacia plantation from 10:00 h to 16:00 h. Oaten hay (500 g) was distributed to lambs in the barn at 16:30 h. Each of the three experimental periods lasted 4 weeks. When lambs were on acacia diet they showed a significantly lower mean faecal egg counts (FECs) than those on grass, 849.1 ± 453.6 epg and 1001.8 ± 511.8 epg, respectively. The addition of PEG to the acacia diet resulted in an increase in the daily weight gain and plasmatic uraemia concentrations to levels similar to that in the case of grass. However, the FECs (863.4 ± 434.6 epg) were not increased by comparison to acacia group.

Duration of Anthelmintic Effect of Three Formulations of Ivermectin (Oral, Injectable and Pour-on) Against Multiple Anthelmintic-Resistant Haemonchus contortus in Sheep

We report the results of investigations that were conducted in a sheep flock in Uttaranchal, India where repeated failure of anthelmintic medication was noted. The study revealed that Haemonchus contortus in sheep had developed resistance to benzimidazoles (fenbendazole, mebendazole and albendazole), imidazothiazole (levamisole) and salicylanide (rafoxanide), while it was fully susceptible to avermectins (ivermectin). Further, the suppression of nematode egg output in faeces of sheep naturally infected with multiple anthelmintic-resistant H. contortus following treatment with ivermectin tablet (0.4 mg/kg body weight (bw), orally), ivermectin injection (1% w/v, 0.2 mg/kg bw, subcutaneously) and ivermectin pour-on (0.5 w/v, 0.5 mg/kg bw) was also studied over a period of 10 weeks post treatment. It was noted that ivermectin tablet after initial clearance of infection (faecal egg count reduction 100%), could not prevent establishment of new patent natural infection for even a single day, while ivermectin pour-on and injection prevented the establishment of new infection for 7 and 14 days post treatment, respectively. Maximum protection period (duration for which mean faecal egg count of sheep reaches 500 eggs per gram of faeces or more) of 68 days was recorded in sheep treated with injectable ivermectin, followed by pour-on (60 days) and oral (53 days) preparations.

Prevalence and intensity of intestinal helminths found in free-ranging golden lion tamarins ( Leontopithecus rosalia, Primates, Callitrichidae) from Brazilian Atlantic forest

Helminth identification and egg counts were performed in 316 fecal samples during 4 years in 199 golden lion tamarins (GLTs), Leontopithecus rosalia, from two Brazilian conservation units. Tamarin sex and age, area of occurrence and helminth co-infection were tested as potential factors that could affect helminth prevalence and egg shedding in host individuals. Three nematodes species were found at low prevalences but not in both conservation units: Ancylostomatidae (12%), Ascarididae (1%) and Tripanoxyuris minutus, an Oxyuridae (4%). Three other species had high prevalences and were found in both conservation units: one acanthocephalan, Oncicola sp. (30%), and two nematodes, Spiruridae (24%), and Trichostrongylidae (31%). These three latter helminths had distinct prevalences between the conservation units, probably due to differences in availability of helminth infective stages in each area. Prevalences were greater in females for all helminth species; this was especially the case for Oncicola sp. Sex and age differences in helminth prevalence may be associated with changes in sexual steroid levels that accompany age and reproductive status. Frequency of simultaneous infections by the two helminths considered most pathogenic ( Oncicola and Trichostrongylidae) were statistically lower than expected; this may be related to: (i) higher tamarin death rate caused by the association; (ii) differences in exposure to helminth infective stages in the various areas of occurrence; (iii) and competition between these helminth species. All helminth species followed a negative binomial distribution, with stronger clumping occurring in Trichostrongylidae and in female GLTs. Distinct transmission strategies of Oncicola sp. and Spiruridae, in contrast with Trichostrongylidae, may partially explain the different clumping levels of these helminths in GLTs. Mean fecal egg counts of all helminths were not different between GLT sexes, ages or areas of occurrence. The three most common helminth species may be a threat to isolated or dense GLT populations.

Prevalence and seasonal changes in the population of gastrointestinal nematodes of small ruminants in the semi-arid zone of north-eastern Nigeria

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.

Cases of reduced cyathostomin egg-reappearance period and failure of Parascaris equorum egg count reduction following ivermectin treatment as well as survey on pyrantel efficacy on German horse farms

In 2003 and 2004, on a total of 63 different German horse farms, a survey using the faecal egg count reduction (FECR) test was performed to investigate the efficacy of ivermectin (IVM, Ivomec ®) and pyrantel (PYR, Banminth ®) treatment against gastro-intestinal nematodes in a total of 767 horses. IVM treatment resulted in 100% reduction of the cyathostomin egg production 14 and 21 days post-treatment (d.p.t.) on 37 farms. On the remaining five farms, the mean faecal egg count reduction ranged between 97.7 and 99.9%. The mean cyathostomin FECR following PYR treatment ranged between 92.2 and 100% on the 25 farms tested. Therefore, based on the 90% FECR threshold suggested for detection of anthelmintic resistance in horses, neither IVM nor PYR anthelmintic resistance was detected. However, if the thresholds recommended for the detection of resistance in small ruminants were applied, on one and four farms signs of reduced IVM and PYR efficacy, respectively, were observed. In 2005, to further investigate these findings, the cyathostomin egg-reappearance period (ERP) following IVM treatment was examined on six selected farms, two of which were found to show less than 99.8% FECR in the previous survey. On these two latter farms, the ERP was less than 5 weeks, while on the other four it was at least 8 weeks. Earlier investigations described IVM cyathostomin ERP of at least 9 weeks. The efficacy of IVM to reduce Parascaris equorum egg excretion was also studied. On one farm in 2 consecutive years, IVM treatment did not lead to a significant reduction in P. equorum faecal egg counts in one and five young horses, respectively.

A 3-year field evaluation of pasture rotation and supplementary feeding to control parasite infection in first-season grazing cattle—Effects on animal performance

To evaluate non-chemical strategies to control pasture-borne parasites in first-season grazing (FSG) cattle, a 3-year grazing trial was conducted during 2002–2004 on naturally infected pastures on a commercial beef cattle farm in Sweden. A uniform pasture was divided in 4 equal 2 ha paddocks onto each of which 10, 5–9 months old dairy breed steer calves were allocated at turn-out in May each year. Two strategies were evaluated: (1) turn-out onto pasture which had been grazed the previous year by second-season grazing (SSG) steers, followed by a move to aftermath in mid-July (RT) and (2) supplementation with concentrate and roughage for 4 weeks from turn-out (FD). Comparisons were made with an untreated (UT), and an anthelmintic treated control group (DO). Animal parasitology and performance were monitored monthly throughout the 20 weeks grazing period. Additional sampling occasions were performed on day 9 (for coccidia) and 10 weeks after turn-out (mid-July). Due to clinical parasitic gastro-enteritis (PGE), salvage treatments were performed on all animals in group FD approximately 7 weeks after turn-out in 2003 and of three animals in group UT 5 weeks after turn-out in 2004. In 2003, the geometric mean oocyst excretion 9 days after turn-out was approximately 150,000 opg of mainly Eimeria alabamensis in group FD, and in 2004 approximately 180,000 opg in group UT. Apart from the DO group, geometric mean faecal egg counts (FEC) were between 80 and 400 epg 4 weeks after turn-out. Mean serum pepsinogen concentrations (SPC) of approximately 3.6 U tyrosine were recorded in the FD and UT groups from late August 2002. In 2003 and 2004, mean concentrations in these groups were between 4.1 and 7.2 U tyrosine 8 weeks after turn-out. By the end of the three grazing seasons the average weight gain difference compared to the DO group was for FD −29, −38 and −5 kg and for RT −4, −21 and +14 kg, and compared to the UT group −18, +2 and +22 for FD and +7, +19 and +41 kg for group RT. In conclusion, the rotation control strategy showed promising results, whereas the strategic feeding was poor from a parasite control standpoint.

Effect of CD4 + T lymphocyte depletion on resistance of Gulf Coast Native lambs to Haemonchus contortus infection

It has been reported that CD4 + T lymphocytes are important in acquired immunity to gastrointestinal nematode infection. Whether these lymphocytes are also involved in the immune response of naturally resistant Gulf Coast Native (GCN) sheep to Haemonchus contortus infection remains to be defined. The objective of this study was to determine the role of CD4 + T lymphocytes in this resistance. Ten GCN lambs were randomly assigned to a control ( n = 5) or a treatment ( n = 5) group. The treatment consisted of a series of IV injections with mouse anti-ovine CD4 + T lymphocyte monoclonal antibodies for a period of 3 weeks. After the second treatment, all lambs were experimentally infected with 10,000 H. contortus infective larvae by oral inoculation. All lambs were monitored for fecal egg counts, blood packed cell volumes, white blood cell differential counts and serum antibody responses on a weekly basis. Fluorescence-activated cell sorter (FACS) analysis was done biweekly to enumerate CD4 + T lymphocytes in peripheral blood. Necropsies were performed at the end of the study and 10% of the contents of the gastrointestinal tract were preserved for nematode enumeration and identification. Also at necropsy, mesenteric lymph nodes were extracted and FACS analysis was run on lymphoid cells. Mean fecal egg counts on day 21 and 28 post-infection and nematode counts at necropsy of the treated group were significantly ( p < 0.05) higher than that of the control group. Percent CD4 + T lymphocytes in peripheral blood was significantly ( p < 0.05) lower in the treatment group than in the control group from day 9 to the end of the study. No differences were found in blood packed cell volumes, white blood cell differential counts, antibody titer or lymph node CD4 + lymphocytes between groups. Lambs depleted of their CD4 + T lymphocytes were more susceptible to H. contortus infection than undepleted lambs. The results of this study suggest that CD4 + T lymphocytes are associated with the natural resistance of GCN sheep to H. contortus infection.

Control of endoparasites in horses with a gel containing moxidectin and praziquantel

A gel formulation containing moxidectin (20 g/kg) and praziquantel (125 g/kg) reduced the geometric mean faecal strongyle egg count in horses to below 100 eggs per gram of faeces (epg)...

Effect of forage legumes and anthelmintic treatment on the performance, nutritional status and nematode parasites of grazing lambs

Recent studies in New Zealand and the UK have shown that certain forages reduce parasitic infection in sheep. The aim of this experiment was to investigate the effects of legume forages compared to ryegrass on interactions between production, nutritional status and nematodes in grazing lambs. Twenty-four male lambs per forage treatment, half of which were treated with anthelmintics on Day 0, grazed monocultures of lucerne ( Medicago sativa), red clover ( Trifolium pratense) and white clover ( Trifolium repens) and were compared with lambs grazing perennial ryegrass (Lolium perenne). Individual faecal egg counts (FEC) and liveweight were determined every 7 days for 56 days, after which half the lambs were slaughtered to determine total nematode intensities (TNI). Results showed that lambs grazed on red or white clover, but not lucerne, had lower pooled mean FEC and improved liveweight performance compared to lambs grazing ryegrass. Lambs treated with anthelmintics had higher TNI compared to lambs not treated, due to a trend for more adult nematodes in lambs grazing lucerne and treated with anthelmintics than all other lambs, except those grazing red clover and also given anthelmintics. Lambs grazing white clover tended to have fewer adult nematodes than lambs grazing other forages. Examination of the nematode species showed a change in female T. circumcincta occurred in all lambs following anthelmintic treatment and that the forage species grazed by lambs affected individual parasite species. Lambs grazing white clover had fewer male and adult T. circumcincta compared to lambs grazing other forages, and lambs grazing lucerne had fewer adult T. circumcincta compared to lambs grazing ryegrass or red clover. Data on small intestine TNI showed that lambs grazing lucerne and given anthelmintics had more male adult nematodes than other lambs, except those grazing red clover and treated with anthelmintics. Results indicate that lucerne and red clover both increase the re-infection of grazing lambs with Trichostrongylus species compared to ryegrass following anthelmintic treatment. In conclusion, legume forages have the potential to contribute to the control of abomasal but not small intestine nematode parasites in finishing lamb systems.