Control Of Gastrointestinal Nematodes Research Articles

Ovicidal and larvicidal activity of the crude extracts from Phytolacca icosandra against Haemonchus contortus

The development of anthelmintic resistance has impacted on the success of conventional anthelmintics (AH) for the control of gastrointestinal nematodes in grazing/browsing sheep and goats. Medicinal plants from the traditional herbolary in Mexico may provide new candidates that can be explored as alternative sources of AHs for ruminants. This study evaluated the leaf extracts derived from Phytolacca icosandra against infective L 3 larvae and eggs from Haemonchus contortus collected from sheep. Three extracts of different polarities were obtained from the leaf plants using ethanol, n-hexane and dichloromethane as the solvents. The effectiveness of the in vitro AH activity of the plant extracts was evaluated using larval migration inhibition (LMI) and egg hatch (EHA) assays. For the LMI assays, the ethanolic extract of P. icosandra showed 55.4% inhibition of larval migration at 2 mg/mL ( p < 0.05). The dichloromethane extract of P. icosandra showed 67.1% inhibition of migration at 3 mg/mL ( p < 0.05) and a dose-dependent response with an LD 50 of 0.90 mg/mL. The n-hexane extract failed to show inhibition of larval migration at any concentration explored. In the EHA for the ethanol extract, the lowest concentration tested (0.15 mg/mL) resulted in inhibition of egg hatching greater than 72.6%. Therefore, the LD 50 could not be calculated for this extract. The LD 50 of the dichloromethane extract of P. icosandra was 0. 28 mg/mL. An egg hatch inhibition greater than 90% was observed with both the ethanolic and dichloromethane extracts when using a concentration of 0.90 mg/mL or higher. The n-hexane extract failed to show egg hatch inhibition at any concentration tested. The AH activity reported for P. icosandra could be attributable to the flavonoids, steroids, terpenoids, coumarins and/or saponins that were present in the ethanolic and dichloromethane extracts. A combination of more than one component may also explain the observed AH activity against the H. contortus life stages that were evaluated. In conclusion, the ethanolic and dichloromethane extracts of P. icosandra showed clear in vitro AH activity against the H. contortus eggs and the L 3 larvae. However, the hexanic extract of the plant leaves failed to show any in vitro AH activity.

A comparison of two integrated approaches of controlling nematode parasites in small ruminants

Control of gastrointestinal nematodes (GIN) in small ruminants in regions of the world where anthelmintic resistance is prevalent must rely on more than just chemical deworming strategies. The objective of this experiment was to compare two integrated treatment protocols for control of GIN (primarily Haemonchus contortus in this region) using anthelmintics, copper oxide wire particles (COWP) and FAMACHA ©, compared to traditional anthelmintic use only. Three separate trials were conducted on mature ewes, weaned goats, and weaned lambs in which three deworming management strategies were applied: 1) all animals were dewormed with levamisole at four week intervals (LEV), 2) individual animals were dewormed with moxidectin when scored ≥ 4 (ewes) or ≥3 (kids and lambs) using FAMACHA © (FAM/MOX), 3) all animals were dewormed with moxidectin initially and again with COWP (2 g) when group mean FEC exceeded 500 (ewes), 3000 (kids), or 1000 (lambs) eggs/g (MOX/COWP). In this final group, during periods between group treatments, individual animals were dewormed with albendazole and levamisole according to FAMACHA © score. Fecal egg counts (FEC) and blood packed cell volume (PCV) were determined every 7 days and body weight every 28 days for 30, 20, or 16 weeks in ewes, goats, and lambs, respectively. Efficacy of levamisole was 83.4–86.4%, efficacy of moxidectin was 93.5–100%, and efficacy of COWP was 10.8–98.1% among the three trials. The mean number of deworming treatments per animal that occurred for the LEV, FAM/MOX, and MOX/COWP groups, respectively, was 7.9, 0.6, and 2.5 ± 0.4 ( P < 0.001) for ewes, 5.2, 1.6, and 3.4 ± 0.3 ( P < 0.001) for goats, and 4.0, 1.7, and 3.6 ± 0.2 ( P < 0.001) for lambs. Production (body weight of lambs weaned from ewes or final body weight of kids and lambs) was similar among management strategy groups for ewes and kids, but FAM/MOX lambs were lighter by the end of the trial ( P < 0.003). While more time and labor was required to use the FAMACHA © system, a more conservative use of anthelmintics occurred in the FAM/MOX group.

European field study of the efficacy and safety of the novel anthelmintic monepantel in sheep

During 2007, a large-scale controlled, multicentre, blinded and randomised field study was conducted in Scotland, England and France to assess the efficacy and safety of monepantel, the first molecule to...

A suite of genes expressed during transition to parasitic lifestyle in the trichostrongylid nematode Haemonchus contortus encode potentially secreted proteins conserved in Teladorsagia circumcincta

The control of gastro-intestinal nematodes remains largely based on anthelminthic treatments, however spreading of anthelmintic resistance has reduced their efficacy. The genes involved in the transition to parasitic lifestyle could constitute targets of interest to develop alternative control strategies. In the trichostrongylid nematode Haemonchus contortus, we have used a SSH (Suppressive Subtractive Hybridization) based approach to generate two distinct subtracted cDNA libraries specifically enriched in cDNA expressed during the early parasitic fourth stage larvae L4 (5 days post-infection). A total of 200 clones were subjected to dot-blot experiments and 46 clones were selected for further characterization. The 46 corresponding expressed sequence tags (EST) were found to cluster into nine contigs. The corresponding full-length cDNA was obtained for all candidates. The genes encoding potentially secreted proteins were investigated in more detail. RT-PCR experiments confirmed their specific expression or over expression from the early L4 larvae to the adult stages and search for homologs in the trichostrongylid species T. circumcincta was performed in order to investigate whether they may be novel cross-specific targets.

Anthelmintic activity of Pistacia lentiscus foliage in two Middle Eastern breeds of goats differing in their propensity to consume tannin-rich browse

The Damascus and Mamber breeds of goats thrive in Middle Eastern Mediterranean regions where the tannin-rich (20% of polyethylene glycol-binding tannins) brush species Pistacia lentiscus L. (lentisk) is ubiquitous. In light of the increasing recognition of the anthelmintic activity of plant tannins, we examined the effect of offering lentisk foliage for 24 days on fecal egg excretion in 5.5-month-old Damascus and Mamber kid goats ( n = 28) following infection with 10,000 L3 larvae of mixed gastro-intestinal nematodes (GIN). Lentisk foliage was consumed with or without a daily supplement of 20 g polyethylene glycol (PEG; MW 4000). Lentisk tannins showed a strong protein-depletive effect that was totally reversed by the addition of PEG. At the peak of infection, kids of the two breeds lost weight unless they were fed with lentisk without PEG. Fecal egg counts (FEC) were lowest – and did not differ from 0 – in kids fed lentisk without PEG, highest in the controls fed hay as roughage, and intermediate in kids fed lentisk and PEG (241, 1293, and 705 eggs per gram, respectively, SEM 180; P < 0.001); therefore, the anthelmintic activity of lentisk was only partly attributable to tannins. The suppressive effect of lentisk on FEC ceased when feeding was discontinued, suggesting that female parasites were not killed but their fertility was reversibly impaired. Damascus kids showed lower FEC than their Mamber counterparts, inferring that the effect of foraging on tannin-rich species is only additive to genetic differences between goat breeds in their sensitivity to GIN infection. On the basis of our results we would expect yearlong lentisk grazing to result in no or very low GIN infection, and Damascus goats to have some advantage over Mamber goats where chemical control of GIN is unfeasible. There appears to be a trade-off between the benefits of lentisk tannin as drug and its side-effects (protein depletion) when given at high level; how goats balance this trade-off requires further elucidation.

Using copper oxide wire particles or sericea lespedeza to prevent peri-parturient gastrointestinal nematode infection in sheep and goats

Gastrointestinal nematodes (GIN) continue to plague the small ruminant industry, especially in parts of the world with warm, humid climates. Alternatives to chemicals are needed for GIN control because of anthelmintic resistance and a desire to reduce chemical residues in meat products. Three experiments using peri-parturient does or ewes addressed the objective: 1) in Arkansas, meat goats were untreated ( n = 20) or fed copper oxide wire particles (COWP; 2 g each) in pelleted sericea lespedeza ( Lespedeza cuneata; n = 22) before kidding while consuming sericea lespedeza hay, 2) in Arkansas, 42 Katahdin ewes were randomly assigned to remain untreated or were fed COWP (2 g each) before lambing within groups fed bermudagrass ( Cynodon dactylon) or sericea lespedeza hay in a 2 × 2 factorial design, 3) in Louisiana, Gulf Coast Native ewes were randomly assigned to remain untreated or were fed COWP (4 g each) in a pelleted ration ( n = 10 each) after lambing began. Fecal egg counts (FEC) and blood packed cell volume (PCV) were determined weekly in all experiments, and coproculture to examine GIN species was conducted in the first two experiments. Haemonchus contortus is typically the predominant GIN in the southeastern U.S., even during cooler months. However, Trichostrongylus spp. was the predominant GIN in Arkansas during these experiments. In all of the experiments, feeding COWP led to a reduction in FEC, but no change in PCV. The sericea lespedeza hay fed to ewes in Experiment 2 was associated with a reduction in FEC compared with ewes fed bermudagrass hay. Kids and lambs from COWP-treated dams in two experiments were lighter than those from untreated dams. Sericea lespedeza aided in the control of GIN infection, and while feeding COWP to peri-parturient ewes and does offered some reduction in GIN infection, body weight of offspring at birth and 60 or 90 days of age may be reduced.

Ostertagia ostertagi in first-season grazing cattle in Belgium, Germany and Sweden: General levels of infection and related management practices

The objective of this study was to determine the prevailing levels of infection with Ostertagia ostertagi in first-season grazing calves and related management factors in three European countries (Belgium, Germany and Sweden). A cross-sectional survey was performed in first-season grazing dairy cattle during 2 consecutive years. Levels of infection with O. ostertagi were assessed by a standardized serum pepsinogen assay at the end of the grazing periods 2006 and 2007 and information on control measures against gastrointestinal nematodes were collected at the same time through a questionnaire. Information was collected from a total of 358 herds in 2006 and 726 herds in 2007. The general infection patterns were similar in the different countries and the 2 years with the majority of the herds having a low (<1 U Tyr) or intermediate pepsinogen result (1–3 U Tyr) and only 2–6% of the herds having levels of infection that are considered to induce significant production losses (>3 U Tyr). The level of nematode control was high in each country, which is illustrated by the widespread use of anthelmintics (69–83% of herds) and the frequent combination of anthelmintic use and control through pasture management (>50% of herds combined two or more protective measures). However, the used control methods showed clear differences between the countries. After taking into account the effect of anthelmintic treatment, herd mean pepsinogen levels were significantly lower in large herds, in calves grazing on a small paddock (vs. pasture) and on mown (vs. non-mown) pastures and if turn out on pasture was postponed. The collected data may serve as a baseline from which we can monitor the methods and success of gastrointestinal nematode control in dairy cattle.

Control of Horn Flies (Haematobia irritans) and Gastrointestinal Nematodes and Its Relation with Growth Performance in Stocker Cattle

<h2>ABSTRACT</h2> The objective of this study was to assess the effects of horn fly and gastrointestinal (GI) nematode control on the performance of stocker cattle grazing Bermudagrass in Louisiana. A total of 168 (56 per trial) weaned calves were available for 3 trials. Stocker cattle were stratified by sex and BW and randomly assigned to 2 replicate treatment groups. The treatments were 1) no horn fly or GI nematode control; 2) horn fly control administrated with insecticidal ear tags, sprays, and pour-ons; 3) GI nematode control administrated every 28 d with fenbendazole; and 4) both horn fly and GI nematode control. Lengths of the trials were 84, 98, and 112 d for trials 1, 2, and 3, respectively, and trials were initiated in early to mid-May of each year. Horn fly and fecal egg counts were conducted periodically. Stocker cattle treated for horn flies had lower (P<0.05) fly counts than control cattle for each trial; however, counts for treated stocker cattle ranged from 42 to 62 flies per side. Stocker cattle treated with fenbendazole had lower (P<0.01) fecal egg counts than controls 14 d posttreatment in all 3 trials. In trials 1 and 2, stocker cattle treated for both horn flies and GI nematodes had 0.14 and 0.23kg greater ADG (P<0.06), respectively, compared with untreated stocker cattle. Under the conditions of this study, even with a lack of effective horn fly control, improved growth rates were achieved for stocker cattle when treated for both external and internal parasites.

Genetic parameters for resistance to trichostrongylid infection in dairy sheep

In sheep, the traditional chemical control of gastrointestinal nematode (GIN) parasites with anthelmintics has led to the widespread development of anthelmintic resistance. The selection of sheep with enhanced resistance to GIN parasites has been suggested as an alternative strategy to develop sustainable control of parasite infections. Most of the estimations of the genetic parameters for sheep resistance to GIN parasites have been obtained from young animals belonging to meat- and/or wool-specialised breeds. We present here the estimated genetic parameters for four parasite resistance traits studied in a commercial population of adult Spanish Churra dairy ewes. These involved two faecal egg counts (FECs) (LFEC0 and LFEC1) and two serum indicator traits, the anti-Teladorsagia circumcincta fourth stage larvae IgA (IgA) and the pepsinogen (Peps) levels. In addition, this study has allowed us to identify the environmental factors influencing parasite resistance in naturally infected Spanish Churra sheep and to quantify the genetic component of this complex phenotype. The heritabilities estimated for the two FECs analysed (0.12 for LFEC0 and 0.09 for LFEC1) were lower than those obtained for the examined serum indicators (0.19 for IgA and 0.21 for Peps). The genetic correlations between the traits ranged from 0.43 (Peps−IgA) to 0.82 (LFEC0−LFEC1) and were higher than their phenotypic counterparts, which ranged between 0.07 and 0.10. The heritabilities estimated for the studied traits were lower than previously reported in lambs. This may be due to the differences in the immune mechanisms controlling the infection in young (antibody reactions) and adult (hypersensitivity reactions) animals/sheep. In summary, this study demonstrates the presence of heritable variation in parasite resistance indicator traits in the Churra population studied, which suggests that genetic improvement is feasible for this complex trait in this population. However, further studies in which the experimental variables are controlled as much as possible are needed to identify the best trait that could be measured routinely in adult sheep as an indicator of parasite resistance.

Administration of copper oxide wire particles in a capsule or feed for gastrointestinal nematode control in goats

Widespread anthelmintic resistance in small ruminants has necessitated alternative means of gastrointestinal nematode (GIN) control. The objective was to determine the effectiveness of copper oxide wire particles (COWP) administered as a gelatin capsule or in a feed supplement to control GIN in goats. In four separate experiments, peri-parturient does ( n = 36), yearling does ( n = 25), weaned kids ( n = 72), and yearling bucks ( n = 16) were randomly assigned to remain untreated or administered 2 g COWP in a capsule (in Experiments 1, 2, and 3) or feed supplement (all experiments). Feces and blood were collected every 7 days between Days 0 and 21 (older goats) or Day 42 (kids) for fecal egg counts (FEC) and blood packed cell volume (PCV) analyses. A peri-parturient rise in FEC was evident in the untreated does, but not the COWP-treated does (COWP × date, P < 0.02). In yearling does, FEC of the COWP-treated does tended to be lower than the untreated (COWP, P < 0.02). FEC of COWP-treated kids were reduced compared with untreated kids (COWP × date, P < 0.001). FEC of treated and untreated bucks were similar, but Haemonchus contortus was not the predominant nematode in these goats. However, total worms were reduced in COWP-fed bucks ( P < 0.03). In summary, it appeared that COWP in the feed was as effective as COWP in a gelatin capsule to reduce FEC in goats. COWP administration may have a limited effect where H. contortus is not the predominant nematode.

A pooled analysis of the efficacy of monepantel, an amino-acetonitrile derivative against gastrointestinal nematodes of sheep

Monepantel is the first compound from the amino-acetonitrile derivative class of anthelmintics to be developed for the control of gastrointestinal nematodes of sheep. An analysis of pooled data from a series of controlled studies is reported providing a single point of efficacy (+/- 95% confidence interval) for each gastrointestinal nematode tested at the fourth larval and/or adult stages. For most nematode species, the pooled efficacy was greater than 99%, and for the remaining few species, efficacy was greater than 90%. These data are well supported by field studies conducted across five countries, where the pooled efficacy (on the basis of fecal worm egg count reduction) was in most cases, greater than 99% (depending on the calculation used). Monepantel is highly effective when administered to sheep at 2.5 mg/kg, and its introduction as a new anthelmintic for sheep is timely, given the problems with anthelmintic resistance that the world's sheep farmers are now experiencing.

The relative contributions of T. colubriformis, T. vitrinus, T. axei and T. rugatus to sheep infected with Trichostrongylus spp. on the northern tablelands of New South Wales

This survey was designed to determine the spatial and temporal distribution and the relative contributions of Trichostrongylus colubriformis, Trichostrongylus vitrinus, Trichostrongylus axei and Trichostrongylus rugatus to sheep infected with Trichostrongylus spp. on the northern tablelands of NSW. Thirty completed larval cultures were collected from a commercial parasitology laboratory servicing the northern tablelands of NSW between June and December 2007. Cultures were selected at random from farms within the study area whenever the combined results of faecal worm egg counting and coproculture indicated >200 Trichostrongylus spp. eggs per gram and >40% Trichostrongylus spp. respectively. Selection of cultures was constrained to prevent multiple samples from a single grazing property. Larval cultures were stored at 4 °C and subsequently used to artificially infect GIN-free sheep which were sacrificed for the collection of gut contents at 3 weeks post-infection. Abomasal contents were examined for the presence of T. axei. From the anterior small intestine 100 adult male Trichostrongylus spp. per animal were identified to species ( T. colubriformis, T. vitrinus or T. rugatus) according to spicule morphology. T. colubriformis was the most prevalent Trichostrongylus species (present in 100% of the samples) as anticipated in a summer rainfall region. T. vitrinus was present in 20% of the samples whilst T. rugatus was present in only 10% of the samples, yet when present comprised a much higher proportion of the total Trichostrongylus population than has previously been reported. In an unexpected result, T. axei was not identified in any of the samples collected. The epidemiological basis for these results and the implications for gastro-intestinal nematode control are discussed.

Gastrointestinal nematode infections in adult dairy cattle: Impact on production, diagnosis and control

Due to the intensification of dairy herds and the recognition of subclinical infections with a negative impact on production as disease, control of gastrointestinal (GI) nematodes in adult cows is becoming established in an increasing number of dairy herds. The objectives of this paper are to review the aspects related to the impact on production, diagnosis and control of GI nematodes in adult dairy cattle. During the last decade substantial evidence has been generated that GI nematodes can have a negative impact on the performance of adult animals. The milk-yield response to anthelmintic treatment in recent studies in pastured dairy herds was observed to be around 1 kg/cow per day, whereas effects on reproductive performance remain equivocal. GI-nematode infections can be monitored based on Ostertagia ostertagi-specific antibody measurement, which provides information on the level of larval exposure and an indication of the associated production losses. Other diagnostic parameters are considered of limited use in adult cattle. Control relies on anthelmintic treatment and grazing management, which can be used complementary to each other. There are three critical points that need to be considered when developing anthelmintic control recommendations in adult cows: the unpredictability of the treatment response, the timing of treatment and the risk for developing anthelmintic resistance. As a consequence, monitoring of GI-nematode infections is desirable in order to focus anthelmintic treatments on those herds with a high larval challenge and associated production losses. For the future, more studies are needed to evaluate the effects of different control approaches in terms of financial benefits for the farmer and sustainability on the long term.

The role of targeted selective treatments in the development of refugia-based approaches to the control of gastrointestinal nematodes of small ruminants

Anthelmintic resistance is recognised as a major problem affecting small ruminant production worldwide and now threatens the sustainability of many of these systems. One method that has been proposed to prolong the efficacy of our current anthelmintics is the maintenance of a parasite population in refugia (unexposed to a drug) which will maintain the genes for susceptibility within the parasite population. Management strategies that employ refugia-based methods include targeted or strategically timed whole flock treatments, targeted selective treatments (TST), whereby only a proportion of the flock is treated at any one time, and the dilution of resistant with susceptible parasites. The ability to effectively target anthelmintic use relies on the identification of those animals that will most benefit from treatment. This review explains the concept of refugia, describes the role of refugia-based approaches to the management of anthelmintic resistance and reviews the markers that have been studied as indicators for TSTs as well as the implementation of refugia-based strategies. Recent results suggest that targeting anthelmintic treatment on the basis of anaemia, milk production and liveweight gain may offer a means of reducing anthelmintic usage whilst still maintaining animal performance.

Impact of rotational grazing on management of gastrointestinal nematodes in weaned lambs

Gastrointestinal nematode (GIN) control for ‘natural’ or organic lamb production is needed, especially where Haemonchus contortus is prevalent. The objective was to determine the impact of rotational grazing on GIN infection of weaned lambs. In year 1, naturally infected Katahdin lambs (120 days of age) were randomly assigned to graze (1) continuous bermudagrass (CB; n=14), (2) rotational bermudagrass moved every 3.5 days and returned to original plot 35 days later for three rotations (RB; n=14), or (3) rotational bermudagrass rotated when forage height fell below 10cm (RBH; n=7) where first day of grazing=Day 0. In late summer, all lambs were supplemented with 500g corn/SBM because of poor condition. The following year, similar animals were used and included the CB (n=18) and the RB (n=36) groups only. In both years, fecal egg counts (FECs) and blood packed cell volume (PCV) were determined every 7–14 days and body weight every 28 days. Individuals were dewormed with 0.5g copper oxide wire particles (COWP) when FAMACHA score increased to 3 or more. Between 0 and 3 deworming treatments per lamb were necessary and there tended to be fewer RB than CB lambs dewormed by Day 84 for both years combined (P<0.001). Worm free tracer lambs were introduced to CB (n=6) and RB (n=8) plots following the last rotation during the first year to determine worm burdens after 20 days of grazing. Abomasal worm burden tended to be greater in RB than CB or RBH tracer lambs (P<0.10), but intestinal worm numbers were similar. Differences may be due to differences in grazing patterns among groups. Body weight gains were similar between CB and RB groups. Economic value between the CB and RB lambs was similar based on number of lambs that could have been marketed as organic. For both years, lambs relied exclusively on COWP for GIN control with the exception of one lamb. In summary, while there was a reduced incidence of deworming in the RB compared with the CB group of lambs, estimated economic value of these systems was similar.

Control of horn flies (Haematobia irritans) and gastrointestinal parasites and its relation with cow–calf performance

The objective of this study was to assess the effects of horn fly and gastrointestinal (GI) nematode control on cow–calf performance with a spring-calving system. A total of 508 cow–calf records from two locations in Louisiana were available for study over two trials (2005 and 2006). Cow and calf pairs were stratified by cow age, calf sex, calf age, calf sire breed and calf sire and randomly assigned to three replicate treatment groups across the two locations. The treatments were: (1) no horn fly or GI nematode control; (2) horn fly control administrated to cows with insecticidal ear tags applied in late-May (start of trial); (3) GI nematode control administrated to calves in late-May, mid-July and late-August (each calf received fenbendazole at the rate of 5mgkg−1 body weight); and (4) horn fly and GI nematode control as stated above. Length of the trials ranged from 115 to 124 days (late-May to weaning in late-September or early-October). Cows and calves were weighed at the start of the trial, mid-July and weaning. Weekly horn fly counts were conducted. Individual calf fecal samples were collected in late-May, mid-July, late-August, weaning and 10–14 days after late-May and late-August collections. Cows treated for horn flies had lower (P<0.05) fly counts compared with untreated cows for each trial; however, overall fly counts for the treated cows at one location exceeded over 70 flies per side. Calves treated with fenbendazole had lower (P<0.01) GI nematode fecal egg counts (FEC) for the 10–14 day post-treatment collections. Calves treated GI nematodes and whose dams were treated for horn flies had numerically higher or greater (P<0.05) total calf gains (8.6kg and 11.8kg) in both trials than untreated calves. Weight gain differences for fenbendazole-treated calves compared with untreated calves were of greater magnitude from mid-July to weaning than weight gain differences from late-May to mid-July in both trials. There were no treatment differences for any of the cow response traits. In conclusion, improvement in calf growth from both horn fly and GI nematode treatments were realized even with marginal levels of fly control and a greater response in calf growth resulted when deworming of spring-born calves occurred when they were 4 months of age or older.

Effectiveness of a community-based strategic anthelmintic treatment programme in the control of gastrointestinal nematodes and Fasciola gigantica in cattle in Kilolo district, Tanzania

A longitudinal demonstration project was carried out in 2005/2006 for thirteen months to determine the effectiveness of a strategic community-based worm control (CBWC) programme in the control of gastrointestinal (GI) nematodes and Fasciola gigantica in cattle. Two villages namely, a CBWC village (Ilula-Masukanzi) and a village without CBWC (Kilolo-Luganga) were randomly selected in Kilolo district, Iringa region of Tanzania. Animals in both villages were under the traditional management system and used the village communal grazing area. At the village with CBWC, 60 zebu cattle (6-18 months old) from 10 farms in the village were selected and ear tagged for monthly sampling and weghing. A strategic CBWC programme was instituted whereby all animals in the village (tagged and non-tagged) were treated with albendazole 10% drench at 10 mg/kg four times a year e.g. middle of the rainy season (February), end of the rainy season (May), middle of the dry season (September) and late dry/early rainy season (December). In the village without CBWC, 68 zebu cattle (6-18 months old) from 11 farms in the village were selected and tagged for monthly sampling and weighing. Farmers in the village without CBWC were allowed to continue with their normal management practices including anthelmintic treatments. Faecal and blood samples from tagged animals and pasture samples from communal grazing areas were collected on monthly basis for 13 months. Results showed that strategic CBWC programme was highly effective in reducing faecal egg counts (FEC) and the proportion of animals passing Fasciola eggs in faeces. The strategic CBWC significantly reduced FEC of animals by an average of 60% compared to animals at the village without CBWC (P < 0.01). Four strategic CBWC treatments per year significantly reduced the proportion of animals passing Fasciola eggs in faeces by an average of 82.5% compared to animals at the village without CBWC (P < 0.05). From commencement to the end of the trial, animals at the village with CBWC significantly outgained animals at the village without CBWC by an average of 13.9 kg per year (P < .05). It is concluded that strategic CBWC programme was highly effective in reducing FEC, reducing the proportion of animals passing Fasciola eggs in faeces and improved weight gain in animals.

Atividade ovicida e larvicida in vitro do óleo essencial de Eucalyptus globulus sobre Haemonchus contortus

The objective of this work was to evaluate ovicidal and larvicidal effects of Eucalyptus globulus essential oil (EGEO) on Haemonchus contortus. The chemical composition determination of EGEO was through gas chromatography and mass spectrometry. Egg hatch test (EHT) was performed in concentrations 21.75; 17.4; 8.7; 5.43 e 2.71 mg x mL(-1). In larval development test (LDT) were used the concentrations 43.5; 21.75; 10.87; 5.43 e 2.71 mg x mL(-1). Each trial was conducted by negative control with Tween 80 (3%) and positive control, 0.02 mg x mL(-1) of thiabendazole in EHT and 0.008 mg x mL(-1) of ivermectin in LDT. The maximum effectiveness of EGEO on eggs was 99.3% in concentration of 21.75 mg x mL(-1) and on larvae was 98.7% in concentration 43.5 mg x mL(-1). The concentration of EGEO that inhibits 50% of the eggs and larvae was 8.3 and 6.92 mg x mL(-1), respectively. The oil chemical analysis identified as main component the monoterpen 1,8-cineol. EGEO presented ovicidal and larvicidal activities in vitro, revealing a good potential for use in the control of sheep and goat gastrointestinal nematodes.

Digestibility of Duddingtonia flagrans chlamydospores in ruminants: in vitro and in vivo studies

BackgroundThe use of Duddingtonia flagrans as a tool for the biological control of gastrointestinal nematodes (GIN) is a promising alternative to anthelmintics. The chlamydospores of D. flagrans are orally dosed and their thick cell wall gives them the capacity to resist digestion and pass through the gastrointestinal tract (GIT). Chlamydospores reaching the faeces are able to germinate and trap nematode larvae. The efficacy of this control method is based on reducing the numbers of infective larvae leaving the faeces. Techniques have recently been developed for quantifying the numbers of chlamydospores in faeces. As the number of non-digested spores could be relevant in the design and optimization of dosing programmes for the control of GIN infective larvae, the aim of the present study was to estimate the loss of D. flagrans chlamydospores during their passage through the ruminant gastrointestinal tract using in vitro and in vivo techniques.ResultsAfter in vitro rumen digestion, chlamydospore recovery was not different from the quantity originally incubated (undigested spores) (P > 0.05). In vitro rumen+abomasum digestion caused nearly 36% loss of the chlamydospores originally incubated (P < 0.05). Germination of chlamydospores classified as viable was 24.3%. Chlamydospores classified as non-viable did not germinate. Rumen digestion resulted in more spore germination (R1 = 35.7% and R2 = 53.3%) compared to no digestion (time 0 h = 8.7%). Subsequent abomasal digestion reduced germination (R1+A = 25%) or stopped it (R2+A = 0%). In vivo apparent chlamydospore digestibility in sheep showed a loss of 89.7% of the chlamydospores (P < 0.05).ConclusionsThe loss of chlamydospores was evident under in vitro and in vivo conditions. Negligible amounts of spores were lost during the in vitro rumen digestion. However, in vitro rumen+abomasum digestion resulted in a chlamydospore loss of approximately 36%. In vivo passage through the sheep GIT resulted in a total loss of 89.7% of the orally administered spores.

Eficácia de plantas para o controle de nematóides gastrintestinais de pequenos ruminantes: revisão de estudos publicados

As helmintoses gastrintestinais constituem um dos principais fatores limitantes para a ovinocaprinocultura em todo o mundo e a saúde dos rebanhos depende de um efetivo controle antiparasitário. A resistência aos anti-helmínticos representa um dos entraves para esse controle e a busca por novas bases tem sido um desafio constante. A utilização da fitoterapia na medicina veterinária constitui um campo promissor de pesquisas. Estudos nesta área necessitam da inserção em um contexto agroecológico, tendo como fator limitante o manejo sustentável dos recursos naturais envolvidos. O presente artigo apresenta uma revisão dos estudos de plantas cientificamente testadas no Brasil e em outros países para o controle das parasitoses gastrintestinais em pequenos ruminantes.