Resistance In Gastrointestinal Nematodes Research Articles

Tannin rich peanut skins lack anthelmintic properties

Gastrointestinal nematode (GIN) resistance to synthetic anthelmintics in small ruminants has led to the evaluation of feed sources containing naturally occurring bioactive secondary metabolites that lessen parasite activity. Plants rich in condensed tannins (CT) can have beneficial anthelmintic properties. Peanut (Arachis hypogea L.) skins (testa), an agricultural by-product, are a rich source of CT, have low fiber and high levels of oil and crude protein, and have been incorporated into feed products for the cattle industry. Anthelmintic activity of pellets formulated with peanut skins was compared to that of commercial alfalfa (Medicago sativa L.) pellets (control diet) fed to lambs in two separate experiments, one with initially low (220eggsg−1feces; 2008) and the other high (4260eggsg−1feces; 2009) burden of GIN. In both experiments lambs were maintained on bermudagrass (Cynodon dactyon (L.) Pers.) pastures except when pellets were fed (six lambs per treatment) at 2.3% BW every other day three times a week. Overall, average daily intake of CT as quebracho (Schinopsis sp.) equivalents of peanut skin pellets formulated with 5% molasses was 0.38% BW (low GIN lambs), and that of peanut skin pellets formulated with 48% alfalfa and 7% molasses was 0.53% BW (high GIN lambs). Regardless of the initial level of GIN burden and the formulation of the peanut skin pellets, average daily weight gain of all lambs was about 94±7.2g per day. Increases in fecal egg count and decreases in blood packed cell volumes that occurred during the trials were not significantly different (P>0.05) between lambs fed the control alfalfa pellets and lambs fed peanut skin containing pellets. In these trials, intake of peanut skin may have been insufficient to decrease GIN parasite activity, or perhaps the low prodelphinidin subunit composition of CT in peanut skin prevented a beneficial response.

First Report of Anthelmintic Resistance in Gastrointestinal Nematodes of Sheep from Costa Rica

As the prevalence and severity of anthelmintic resistance continue to rise, nematode infections in sheep correspondingly reduce the profitability of the sheep industry. In Costa Rica, sheep production systems are increasing in both number and importance. A field trial study was carried out to detect the level of anthelmintic resistance to albendazole and ivermectin in gastrointestinal nematodes (GIN) of sheep from seven farms in Costa Rica. Resistance was determined using the fecal egg count reduction test (FECRT). Three treatment groups were assessed on each farm: control, albendazole, and ivermectin. Haemonchus spp. (71%), Strongyloides sp. (57%), and Trichostrongylus spp. (43%) presented resistance levels to albendazole, whereas Strongyloides sp. (43%), Haemonchus spp. (29%), and Trichostrongylus spp. (29%) were resistant to ivermectin. Haemonchus spp., Strongyloides sp., and Trichostrongylus spp. were the most resistant GIN to both products. This study suggests that frequency of treatment, exclusive chemical control, and visual estimation of animal weight to calculate dosage may contribute to the high levels of anthelmintic resistance that were observed on the farms analyzed herein.

Systems biology of ovine intestinal parasite resistance: disease gene modules and biomarkers

This study reports on the molecular systems biology of gastrointestinal nematode (GIN) infection and potential biomarkers for GIN resistance in sheep. Microarray gene expression data were obtained for 3 different tissues at 4 time points from sheep artificially challenged with two types of nematodes, Haemonchus contortus (HC) and Trichostrongylus colubriformis (TC). We employed an integrated systems biology approach, integrating 3 main methods: standard differential gene expression analyses, weighted gene co-expression network analyses (WGCNA) and quantitative genetic analyses of gene expression traits of key biomarkers. Using standard differential gene expression analyses we identified differentially expressed genes (DE) which responded differently in sheep challenged with HC compared to those challenged with TC. These interaction genes (e.g. MRPL51, SMEK2, CAT, MAPK1IP1 and SLC25A20A) were enriched in Wnt receptor signalling pathway (p = 0.0132) and positive regulation of NFκβ transcription factor activity (p = 0.00208). We report FCER1A, a gene encoding a high-affinity receptor for the Fc region of immunoglobulin E, which is linked to innate immunity to GIN in sheep. Using weighted gene co-expression network analysis (WGCNA) methods, we identified gene modules that were correlated with the length of infection (disease modules). Hub genes (with high intramodular connectivity) were filtered further to identify biomarkers that are related to the length of infection (e.g. CAT, FBX033, COL15A1, IGFBP7, FBLN1 and IgCgamma). The biomarkers we found in HC networks were significantly associated with functions such as T-cell and B-cell regulations, TNF-alpha, interleukin and cytokine production. In TC networks, biomarkers were significantly associated with functions such as protein catabolic process, heat shock protein binding, protein targeting and localization, cytokine receptor binding, TNF receptor binding, apoptosis and IGF binding. These results provide specific gene targets for therapeutic interventions and provide insights into GIN infections in sheep which may be used to infer the same in related host species. This is also the first study to apply the concept of estimating breeding values of animals to expression traits and reveals 11 heritable candidate biomarkers (0.05 to 0.92) that could be used in selection of animals for GIN resistance.

In vivo anthelmintic activity of an aqueous extract from sisal waste (Agave sisalana Perr.) against gastrointestinal nematodes in goats

The resistance of gastrointestinal nematodes (GINs) of small ruminants to anthelmintics has required the investigation of new alternatives. The aim of the present study was to evaluate the in vivo anthelmintic activity of an aqueous extract from sisal waste (Agave sisalana) (AESW) against GINs in goats and to observe the animals for toxic effects. Thirty animals that were naturally infected with GINs were distributed into three groups: group I, was treated with daily doses of AESW (1.7g/kg) for eight days; Group II, the positive control, was treated with a single dose of levamisole phosphate (6.3mg/kg); and group III, the negative control, was left untreated. Faecal eggs counts (FECs), coprocultures and post-mortem worm counts were performed to assess the efficacy of the treatments. Clinical and laboratory analyses were performed to evaluate any toxic effects associated with the treatment. In the goats in groups I and II, a significant reduction (p<0.05) of the number of eggs and infective larvae (L3) was observed. The maximum reductions of the FECs were 50.3% and 93.6% for groups I and II, respectively, whereas the percent reductions of the total number of L3 larvae were 80% (group I) and 85.6% (group II). There was no difference between groups I and III with respect to worm burden, and the percent reductions were 28.8% and 63.4% for Oesophagostomum columbianum and Trichostrongylus colubriformis, respectively. No reduction was detected for the Haemonchus contortus. The positive control group demonstrated a 74% reduction of the parasites that were recovered from the digestive tract. There were no changes in clinical and haematological parameters. The levels of serum urea and creatinine were higher in group I, but remained within the normal range. At necropsy, pale mucous membranes, abomasitis and enteritis were associated with parasitism. In addition, a histological analysis of the liver and kidney did not reveal any changes suggestive of toxicity. A chemical analysis of the AESW demonstrated the presence of saponins, which after acid-hydrolyses reaction, gave the sapogenins hecogenin and tigogenin. The AESW had a low efficacy for the parasitic stages and was moderately effective against eggs and free-living stages. Furthermore, the treatment was not toxic to the goats.

Albendazole Failure to Control Resistant Nematodes in Lambs: Lack of Effect of Fasting-Induced Improvement on Drug Absorption

Enhanced plasma availability of albendazole sulphoxide (ABZSO), the active metabolite of albendazole (ABZ), has been described in feed-restricted sheep. The aim of the present work was to determine if the absorption-related pharmacokinetic changes derived from fasting animals prior to drug treatment would modify the clinical efficacy of ABZ against resistant gastrointestinal nematodes in lambs. Forty Corriedale lambs, naturally infected with resistant gastrointestinal nematodes, were divided into 4 groups. Controls were fed ad libitum and did not receive any drug treatment. Treated animals were fed ad libitum up to 30 min prior to treatment with ABZ (3.8 mg/kg) by the intraruminal route. The control (fasted) animals were not fed during the 24-hr period prior to the start of the experiment and did not receive any drug treatment. A second treated group of animals were fasted 24 hr prior to the treatment with ABZ, as previously described for the fed-treated group. Blood samples were collected over a period of 72 hr post-treatment from 6 animals in each treated group. Plasma samples were analyzed by high performance liquid chromatography. The pharmacokinetic parameters were statistically compared using parametric statistical tests. The estimation of the efficacy of the different treatments was performed by the fecal egg count reduction test (FECRT). Additionally, 4 animals randomly chosen from the control-fed and treated groups were killed 13 days post-treatment to evaluate the efficacy against different adult nematode parasites. The results were statistically compared by parametric and non-parametric tests. Significantly (P < 0.05) higher Cmax and AUC values were observed for both the ABZSO and ABZ-sulphone (ABZSO(2)) metabolites in the fasted compared to the fed animals. These kinetic results may be due to a fasting-induced delay in the GI transit time which increases ABZ dissolution and GI absorption. However, a poor ABZ efficacy (measured as FECRT), compatible with a high degree of nematode resistance, was obtained in both fed (48%) and fasted (49%) animals. Haemonchus contortus and Trichostrongylus colubriformis appeared as the more reluctant species with respect to ABZ treatment. The efficacy against H. contortus ranged between 37 (fed) and 54% (fasted) and against T. colubriformis between 0% (fed) and 16% (fasted). Under these experimental conditions, the fasting-induced improvement on ABZ systemic availability (>60%) did not improve its activity against nematodes with a high degree of resistance. However, the data described here for a highly resistant nematode population should not discourage the use of fasting as a practical and well-proven management tool for parasite control in ruminants.

Multiple resistance of gastrointestinal nematodes to nine different drugs in a sheep flock in southern Brazil

Based on clinical observation of a flock of approximately 5000 sheep (breed Merino) from southern Brazil, the failure of anthelmintic treatments was suspected. The sensitivity of the gastrointestinal nematodes that infected these sheep to nine drugs (Levamisole, Moxidectin, Albendazole, Ivermectin, Nitroxynil, Disophenol, Trichlorphon, Closantel, and a combination of Ivermectin, Levamisole and Albendazole) was evaluated. None of the drugs reduced the count of nematode eggs per gram of feces (EPG) in the sheep to an adequate extent (defined as a 95% reduction in EPG). Therefore, we found multiple parasite resistance to all classes of anthelmintic drugs available for small ruminants in the Brazilian market. The genera Haemonchus spp., Trichostrongylus spp. and Ostertagia spp. had various degrees of resistance (or natural tolerance) to each of the drug treatments.

Update on the prevalence of anthelmintic resistance in gastrointestinal nematodes of sheep in New Zealand

Extract Recently, a comparison was made between the prevalence of anthelmintic resistance, determined using faecal egg count reduction tests (FECRT), on randomly selected sheep farms in a systematic national survey (Waghorn et al. 2006) and that derived from similar case material submitted to a veterinary pathology laboratory on a more ad-hoc basis (McKenna 2008). The results of that comparison showed that while there were some differences between them, there were considerable similarities in the prevalence figures obtained from either source. Those similarities, which were particularly evident in terms of the overall pattern of involvement of the various worm genera and the types of anthelmintic concerned, led to the conclusion that FECRT case submissions to veterinary laboratories may offer a useful source of information regarding changes in the prevalence of anthelminticresistant sheep nematodes in New Zealand (McKenna 2008). Accordingly, the present study was undertaken to make further use of this material, to try to ascertain what, if any, such changes may have taken place over the last few years.

Efficacy of anthelmintics on South American camelid (llama and alpaca) farms in Georgia

The number of South American camelid (SAC; llama and alpaca) farms is growing in the southeastern United States, and infection with gastrointestinal nematodes (GIN) is a major health concern in this region. There is widespread resistance to anthelmintic remedies in small ruminants (sheep and goats), but a paucity of information on llamas and alpacas. Anthelmintic resistance was evaluated on three SAC farms (two llama; one alpaca) in Georgia in the southern United States using fecal egg count reduction (FECR) tests. For each farm, animals were randomly assigned to 1 of 5 treatment groups based on initial fecal egg count (FEC) and number of animals available (2-5 groups, n=9-11 per treatment). Ivermectin (IVM, subcutaneous injection; 0.3mg/kg body weight (BW)) and a control group were tested on an alpaca farm, and fenbendazole (FBZ, oral; 10mg/kg BW; two farms), moxidectin (MOX oral; 0.2mg/kg BW; two farms), and levamisole (LEV, oral; 8 mg/kg BW; one farm) were added for the llama farms. Anthelmintic efficacy was determined by comparing FEC of treatment and control animals 14 days post-treatment, with resistance evaluated using the World Association for the Advancement of Veterinary Parasitology (WAAVP) guidelines. Based upon these guidelines, there was GIN resistance to IVM in both llamas and alpacas in Georgia and to FBZ on both llama farms where this drug was tested. There was MOX resistance on one llama farm using the FECR test, while there was no resistance to LEV detected in this study. These data demonstrate a serious emerging problem in the United States of llama and alpaca GIN resistant to drugs from two of the three major anthelmintic classes.

Recherche de la résistance des strongles aux anthelminthiques chez le mouton en Algérie

Une étude de la résistance des strongles gastro-intestinaux aux anthelminthiques chez le mouton a été menée dans une région semi-aride d’Algérie. Deux anthelminthiques (albendazole et ivermectine) communément utilisés ont été testés respectivement sur 120 et 40 animaux dans 14 fermes par le test de réduction de l’excrétion fécale des oeufs (Fecrt). Les résultats ont révélé une grande efficacité de l’ivermectine (&gt; 95 %) à la dose de 0,2 mg/kg de poids vif. L’efficacité globale de l’albendazole à la dose de 5 mg/kg de poids vif a été de 94,2 p. 100, mais elle a été faible (&lt; 90 %) dans quatre à cinq fermes sur dix, et la réduction de l’excrétion fécale des oeufs a été comprise entre 83,3 et 100 p. 100. La persistance de Marshallagia marshalli après traitement a été significativement la plus forte (70,4 %) parmi d’autres strongles gastrointestinaux. L’interprétation du Fecrt à faible nombre d’oeufs par gramme de fèces liée à cette persistance et son rapport avec la présence annuelle de l’espèce chez les ovins ont été analysés.

Efficacy of sericea lespedeza hay as a natural dewormer in goats: Dose titration study

Gastrointestinal nematodes (GIN) parasitism is the greatest threat to economic sheep and goat production in the southern USA, and there is widespread prevalence of GIN resistance to broad-spectrum anthelmintics in this region. A natural alternative for controlling GIN in small ruminants is feeding hay of sericea lespedeza [SL, Lespedeza cuneata (Dum.-Cours., G. Don)], a perennial warm-season legume high in condensed tannins. To determine the level of SL needed to reduce GIN infection, a confinement study was completed with 32 Spanish/Boer/Kiko cross yearling bucks offered one of four diets with 75% hay and 25% concentrate (n=8, 2pens/treatment, 4 goats/pen). The hay portion of each diet consisted of a combination of ground SL (0%, 25%, 50%, and 75% of the diet) and bermudagrass [BG, Cynodon dactylon (L.) Pers.; 75%, 50%, 25%, and 0% of the diet]. The bucks were allowed to acquire a natural GIN infection on pasture prior to moving to the pens. After a 3-week adjustment period in the pens, the goats were stratified by fecal egg count (FEC) and packed cell volume (PCV), randomly assigned to treatments and pens, and then fed the treatment diets for six weeks. During the experimental period, fecal and blood samples were collected from individual animals weekly to determine FEC and PCV, respectively. Adult worms from abomasum and small intestines were collected for counting and identification of species at slaughter. Goats fed SL hay at 25%, 50%, and 75% of the diet had 45.3% (P=0.2048), 66.3% (P=0.0134), and 74.5% (P=0.0077) lower FEC than control animals (75% BG hay) after 21 days. The 50% and 75% SL goats had 84.6% (P=0.0625) and 91.9% (P=0.0340) lower FEC than controls by day 42. The 75% SL-fed goats tended to have higher (P=0.0624) PCV and had fewer (P=0.035) abomasal worms than control animals, while PCV and adult worm numbers of the 50% and 25% SL goats were not different from controls. The optimum level of SL hay in the diet for reducing worm numbers of small ruminants appears to be 75%, whereas 50–75% SL reduces FEC, which could lead to reduced larval infection on pasture.

Genetic markers to gastrointestinal nematode resistance in sheep: a review

Abstract Nematode parasites are the major animal health constraint in sheep production on pasture and cause serious economic losses. Because of failure of anthelmintic drenches, a major research effort has been underway to examine alternatives to chemical control. One of them is selecting sheep which are genetically resistant to parasitic nematodes. However, this last is not widely practiced because of the difficulty of measuring parasite resistance which mostly relies on indirect criteria such as number of nematode eggs passed in the sheep faeces (FEC) packed cell volume (PCV) or enhanced number of eosinophils in peripheral blood. Despite the well known host immune reaction it has been impossible to standardize any immunological parameter and use it as an indicator of parasitic infection. The aim of finding some genetic markers associated with resistance/susceptibility to nematodes is to make diagnostic work easier and conduct an earlier selection of desirable genotypes. However, searching for reliable genetic markers is rather difficult due to different sheep’s manifestation of resistance to either the adult or larval stages of the same parasite species and against the same parasitic stage and various manifestations of the immune responses and antigens against parasites. This review summarizes findings reported in the literature relating to genetic markers to gastrointestinal nematodes resistance in sheep.

Monitoring the efficacy of ivermectin and albendazole against gastro intestinal nematodes of cattle in Northern Europe

Faecal egg count reduction tests (FECRT) using ivermectin (IVM) and benzimidazole (BZ) were conducted to investigate the prevalence of anthelmintic resistance in gastro-intestinal nematodes on cattle farms in Germany, Belgium and Sweden in 2006 and 2007. Based on sufficient numbers of eggs prior to the study, between 3 and 10 farms per country were selected. 10–15 animals were randomly selected per farm and subcutaneously treated with 0.2 mg IVM/kg bodyweight (Ivomec ®, Merial). Faecal samples were collected individually from every animal on day 0 (treatment), day 7 (Belgium & Sweden) or 14 (Germany), and day 21 (Germany, Belgium and Sweden). Faecal egg counts (FEC) were performed at each sampling occasion to estimate the eggs per gram of faeces (EPG) and the reduction of eggs after treatment. The FECRT using IVM in 2006 revealed mean reduction of egg counts between 69–100% on day 7/14 (95% confidence interval (CI) 19–102) and 35–96% (95% CI 0–102) on day 21. Farms with a suggested problem of anthelmintic resistance have been re-visited in 2007 and except for one case all results obtained in 2006 were confirmed in 2007. Larvae obtained from faecal cultures were identified using microscopic identification keys or genus-specific real time PCR. Cooperia oncophora was the predominant species detected after treatment, but Ostertagia ostertagi was found in samples on 3 farms in Germany and 3 farms in Sweden post-treatment. In 2007 additionally a FECRT using benzimidazoles was conducted in Germany and Sweden. In Germany oral Valbazen ® (albendazole, 10%, Pfizer) was used at a concentration of 7.5 mg albendazole/kg bodyweight; in Sweden Valbazen Vet ® (albendazole, 10%, Orion Pharma) at a dose of 8 mg/kg was used. For benzimidazoles an efficacy of 100% was obtained on all tested farms in both countries. This is the first report of a multinational anthelmintic efficacy investigation in cattle in Europe. The results suggest that testing of anthelmintic efficacy should be performed more intensively due to possible insufficient efficacy of current drugs.

Clinical efficacy assessment of the albendazole–ivermectin combination in lambs parasitized with resistant nematodes

Combination of anthelmintic drugs from different chemical groups has been proposed as alternative parasite control strategies where failure of individual drugs is documented. The main goal of the current trial was to compare the clinical anthelmintic efficacy of albendazole (ABZ) and ivermectin (IVM) given either separately or co-administered to lambs naturally infected with gastrointestinal nematodes resistant to both molecules. Seventy (70) Corriedale lambs naturally infected with multiple resistant gastrointestinal nematodes were involved in the efficacy trial: the animals were allocated into 7 experimental groups ( n = 10) and treated with either ABZ intravenously (iv) (ABZ IV), IVM IV, ABZ IV + IVM IV, ABZ intraruminally (ir) (ABZ IR), IVM subcutaneously (sc) (IVM SC) and ABZ IR + IVM SC or kept as untreated controls. The indirect estimation of the efficacy of the different treatments was performed by the faecal egg count reduction test (FECRT). Additionally, four animals randomly chosen from the untreated control and ABZ IV, IVM IV and ABZ IV + IVM IV experimental groups were sacrificed 15 days post-treatment to evaluate the efficacy against different adult resistant nematode parasites. The results were statistically compared by a non-parametric ANOVA (Kruskal–Wallis test). The following egg output reduction values were obtained: 73.4% (ABZ IV), 79.0% (IVM IV), 91.9% (ABZ IV + IVM IV), 43.5% (ABZ IR), 79.8% (IVM SC) and 70.8% (ABZ IR + IVM SC). The efficacy against Haemonchus spp. was 95.1 (ABZ IV), 99.3 (IVM IV) and 99.9% (ABZ IV + IVM IV), while the efficacy against Trichostrongylus colubriformis for the same treatment groups was 79.6, 100 and 99.9%. The data obtained on the assessment of the ABZ–IVM combination indicates that no potentiation synergism is observed. This work is complementary to a parallel study that demonstrated the lack of negative pharmacokinetic interactions between the two anthelmintics acting by different mode of action. Thus, an additive effect may be achieved against nematodes resistant to both compounds. Further work is required to understand the implications of potential pharmacokinetic/pharmacodynamic interactions between anthelmintics before drug combined formulations are developed to be introduced into the pharmaceutical market.

The effects of feeding sericea lespedeza hay on growth rate of goats naturally infected with gastrointestinal nematodes1

Goat production is increasing in the United States due to high ethnic demand, but infection with gastrointestinal nematode (GIN) parasites is a major constraint to the industry. Increasing GIN resistance to chemical anthelmintics worldwide has led to the development of alternative control strategies, including use of forages containing condensed tannins (CT). An experiment was designed using infected and dewormed male kids (Kiko x Spanish, 6 mo old, 18.9 +/- 3.25 kg) fed diets containing 25% concentrate and either 75% sericea lespedeza [SL; Lespedeza cuneata (Dum-Cours.) G. Don], a high CT forage (87 to 181 g of CT/kg), or 75% bermudagrass [BG; Cynodon dactylon (L.) Pers.] hay (n = 10/treatment). The kids were weighed every 14 d, and fecal and blood samples were taken weekly for fecal egg counts and packed cell volume determination, respectively. Fecal cultures were processed every 14 d to determine CT effect on larval development. At slaughter, adult GIN were collected from the abomasum and small intestines for counting and speciation. Blood samples were also analyzed for plasma urea-N, and ruminal VFA and pH were determined. The infected SL-fed kids had consistently lower (P < 0.05) fecal egg counts than the infected BG goats throughout the trial and greater (P < 0.05) packed cell volume beginning by d 77. Average daily gain was greater (P < 0.001) in kids fed SL- than BG-based diets, regardless of infection status (104.3 +/- 5.0 and 75.5 +/- 4.8 g/d, respectively). Total VFA and acetate concentrations were greater (P < 0.001) in the BG- than in SL-fed goats, whereas propionate levels were unaffected by diet. Acetate:propionate ratio (P = 0.01) and plasma urea-N (P = 0.03) levels were greater in BG-fed goats, whereas rumen pH was greater (P < 0.001) in the SL-fed goats. Feeding SL hay can reduce GIN infection levels and increase performance of goats compared with BG hay.

Dietary copper sulfate for control of gastrointestinal nematodes in goats

Prevalence of anthelmintic resistance in gastrointestinal nematodes (GIN) of goats has necessitated studies for alternative means of control. The objective was to determine the effectiveness of dietary copper sulfate for control of GIN in meat goats. Naturally infected buck kids received 0 (LC), 78 (MC) or 158 (HC) mg copper sulfate (CS)/kid daily mixed with concentrate supplement for 63 days. After 42 days the HC group was re-randomized into either the LC or MC treatment. In another study, naturally infected yearling does were offered trace mineral mix with and without CS and intake was estimated to be 140–200 mg CS/day. Goats grazed bermudagrass pastures and were rotated among two or three pastures to minimize pasture effects. Fecal egg count (FEC) and packed cell volume (PCV) were determined every 7 days in the first experiment and 14 days in the second experiment, and goats were weighed every 28 days. On Days 49 and 56 FEC were lower in the HC-treated kids (copper by day, P < 0.02), but FEC were similar on all other days in the first experiment and were similar between the two groups of does in the second experiment. Blood packed cell volume was similar among treatment groups throughout both studies. Body weight was greater in LC compared with MC or HC-supplemented kids on Days 42 and 63 (copper by day, P < 0.04). Body weights of does were similar on Days 0 and 56, but were reduced in those consuming trace mineral with CS on Day 28 (copper by day, P < 0.03). Dietary CS failed to control GIN in this study.

Prevalence of multiple anthelmintic resistant gastrointestinal nematodes in dairy goats in a desolated tract (Pakistan)

This paper presents the first report of anthelmintic resistance (AR) in dairy goats in a desert (Pakistan). Three breeds of dairy goats, i.e. Dera Din Panah, Pak Angora and Beetal, kept at Government Livestock Farm, Rakh Khairewala, district Jhang/Layya, Pakistan, were surveyed for gastrointestinal nematodes (GINs) resistant to commonly used three anthelmintics, i.e. benzimidazole, levamisole and ivermectin. Sixty animals of each breed were selected randomly on the basis of their weight and egg count. Three commonly used anthelmintics, viz., oxfendazole (three different preparations of oxfendazole: fendamex, oxazole, systamex), levamisole and ivermectin, were given at the recommended dose to five groups while one untreated group was kept as control for each breed. Faecal egg counts, faecal egg count reduction test, postmortem worm count and copro-culture were performed to assess the efficacy of selected anthelmintics. The prevalent species of GINs exhibited resistance against all three preparations of oxfendazole. Levamisole in two breeds and ivermectin in all the breeds led to reduction (P< or =0.05) of prevalent species of GINs in both flocks. Haemonchus controtus and Trichostrongylus species exhibited the presence of resistance against oxfendazole preparations which exhibited low efficacy (P> or =0.05). The farm management practices along with the results of the present study revealed the presence of multiple anthelmintic resistant GINs of dairy goats kept in a desolated tract.

Use of FAMACHA system to evaluate gastrointestinal nematode resistance/resilience in offspring of stud rams

High levels of anthelmintic resistance in gastrointestinal nematodes (GIN) of small ruminants have created the need for animals with greater resistance to these parasites. The objective of this experiment was to evaluate the effectiveness of the FAMACHA system in identification of parasite resilient/resistant offspring, and thus identification of stud rams with greater resilience/resistance. Katahdin ewes bred in separate groups to two sires to lamb in spring (2004, 2005: Ram A and Ram B; 2006, 2007: Ram C and Ram D) at the USDA, Agricultural Research Station in Booneville, Arkansas produced 20–40 offspring/sire each year. Ewes and lambs grazed mixed grass (predominantly bermudagrass and ryegrass) pastures and were supplemented with corn/soybean meal between 30 days pre- and 60 days post-lambing (ewes) and starting 45 days of age until weaning (lambs; 95.0 ± 0.6 days of age). Blood samples and feces were collected from the lambs to determine blood packed cell volume (PCV) and fecal egg counts (FEC) and FAMACHA scores were determined at 90, 120, and 150 days of age. Lambs were dewormed if anemic (PCV < 19% or FAMACHA score >2) and data removed within 30 days after deworming. Data were analyzed for the 2004/2005 and 2006/2007 groups using general linear models with year, sex of lamb, and sire nested within year as variables. Sire differences were detected ( P < 0.05 or less) for PCV and FAMACHA at all time points, but not FEC. There tended ( P < 0.10) to be sire differences for FEC at 90 and 120 days of age, but not at 150 days of age. Lambs sired by Ram D were dewormed less by 150 days of age than those sired by Ram C. The FAMACHA system can be used to identify superior sires for parasite resilience/resistance, thus increasing flock resilience, and perhaps resistance.

EFICÁCIA ANTI-HELMÍNTICA EM REBANHO CAPRINO NO ESTADO DE ALAGOAS, BRASIL

Anthelmintic resistance of gastrointestinal nematodes of goats, from the zone of the forest of the Alagoas State, was evaluated. The flocks were split into four groups, one control group and three tested with different drugs: moxidectin, ivermectin and albendazole. The evaluation of the efficiency of each drug was made by reduction test in the count of eggs of feces (RCOF) and differentiation of infective larvae by the fecal culture. Samples of feces were collected before treatment and at days 0 and 7, 14 and 21 post-treatment. The efficiency of albendazole, ivermectin and moxidectin at the days 7, 14 and 21, was 97.89%, 71.2%, 80% for albendazole; 98.74%, 88.3%, 87% for ivermectin; and 83.6%, 96% 96.3% for moxidectin, at the respectivelly days of evaluation. The prevalent infective larvae in fecal cultures were of the gender Haemonchus (95%), revealing resistance to the tested drugs. Keywords: Goats, resistance, anti-helmintic, nematodes.

Effect of pelleting on efficacy of sericea lespedeza hay as a natural dewormer in goats

Resistance of gastrointestinal nematodes (GIN) to anthelmintic treatment has increased pressure to find alternative, non-chemical control methods. Feeding hay of the high condensed tannin (CT) forage sericea lespedeza [SL; Lespedeza cuneata (Dum-Cours.) G. Don.] to sheep and goats has reduced GIN fecal egg count (FEC) and worm numbers in the abomasum and small intestines. This effect has been reported with both unground (long) and ground hay. Pelleting of ground hay increases ease of storage, transport, and feeding, but heating during the pelleting process could reduce biological activity of CT. Eighteen naturally GIN-infected 5–6-month-old Kiko-Spanish cross bucks were fed pelleted and ground SL hay and ground bermudagrass [BG; Cynodon dactyon (L.) Pers.] hay diets ( n = 6 per treatment) in a confinement trial. The bucks were fed the ground BG hay (75% of daily intake) plus a pelleted 16% CP commercial goat chow (25% of daily intake) for 3 weeks, after which they were assigned to treatment groups based upon FEC, 12 animals were switched to ground and pelleted SL hay plus goat chow for 4 weeks, and then all animals were fed the BG ration for one additional week. Throughout the trial, feces and blood were collected from individual animals weekly to determine FEC and blood packed cell volume (PCV), respectively. All goats were slaughtered at the end of the trial, with adult worms in the abomasum and small intestines recovered, counted, and identified to species. Both forms of SL hay reduced ( P < 0.05) FEC in goats relative to BG hay-fed animals, with a greater reduction in goats fed the SL pellets. There was no effect on PCV until the final sampling date, when the SL pellet-fed goats’ PCV increased ( P < 0.05) compared with the other treatments. Feeding pelleted SL reduced ( P < 0.05) abomasal worms, primarily Haemonchus contortus, relative to the BG hay-fed goats. Worm numbers in the goats fed ground SL hay were intermediate. Pelleting SL hay enhanced its efficacy against parasitic nematodes and may facilitate the broader use of this forage in small ruminant GIN control programs.

The resistance of nematode parasites in sheep against anthelmintic drugs widely used in Western Turkey

This study was carried out in seven sheep herds infected by gastro-intestinal nematodes in the Afyonkarahisar district (Western Turkey) from June to July 2005. Sixty sheep in each herd were distributed into 3 groups as anthelmintic treatment groups along with a control group containing 15 animals. The anthelmintic groups were treated with albendazole (7.5 mg/kg BW), oxfendazole (7.5 mg/kg BW)-oxyclosanide (15 mg/kg BW) combination and ivermectin (0.2 mg/kg BW-injectable). The faecal samples were collected before treatment and after 10 days of treatment. Nematode egg counts per gram of faeces (EPG) were examined in the faecal samples using the McMaster technique. To identify the genus, the faecal samples were cultured. The faecal egg count reduction test (FECR) was employed to determine the resistance. In ivermectin treated groups, the FECR% values and the lower confidence limits were estimated as A: 68.57(14.77), B: 46.42(22.47), C: 84.41(35.38), D: 95.23(61.64), E: 97.14(76.94), F: 65.21(80.46) and G: 91.66(31.69), respectively. In the A, B, C, F and G herds, statistical analysis showed that the FECR% values were less then 95% and the estimated lower confidence limits were less then 90%. In all herds, albendazole treated, oxfendazole-oxyclosanide treated and control group, there were no eggs in the feacal samples. In these groups, the FECR% values were 100. In ivermectin treated groups, the third stage larvae from the genera Haemonchus, Oesophagostomum, Trichostrongylus, Cooperia, Nematodirus and Ostertagia were detected in coprocultures before treatment and the larvae from the genera Haemonchus and Oesophagostomum were detected in post-treatment coprocultures in the resistant herds. In conclusion, there was no evidence of resistance in sheep gastro-intestinal nematodes against albendazole and oxfendazole-oxyclosanide; in contrast, the resistance against ivermectin was detected in five sheep herds in the Afyonkarahisar district.