First report of multiple resistance to eprinomectin and benzimidazole in Haemonchus contortus on a dairy goat farm in France

Occurrence of Internal Parasites and Anthelmintic Resistance in Goats

Extensive anthelmintic (AH) use for endoparasitism prevention, especially gastrointestinal strongyle (GIS) infections, led to AH resistance (AR). This study assessed the internal parasitic profile and AR occurrence in goat herds. Five herds (H, n = 300) raised in household systems in Romania (2020-2021) were dewormed with eprinomectin in the fall (H1, H2) and albendazole in the spring (H3-H5). Fecal samples (n = 67) were collected pre- and 14 days post-AH administration. Coprological examinations, coprocultures, and polymerase chain reaction (PCR) were performed. Anthelmintic resistance was detected in H1, H2, and H5. Pre-AH administrations, Eimeria spp. was the most common parasite (95.5%), followed by GIS (91.0%), P. rufescens/M. capillaris (77.6%), Dyctiocaulus filaria (56.7%), and Moniezia spp. (43.3%). Teladorsagia circumcincta (4/5), Trichostrongylus colubriformis (4/5), Oesophagostomum venulosum (3/5), Haemonchus placei (3/5), Haemonchus contortus (2/5), and Cooperia oncophora (2/5) were identified by PCR. Mean OPG/EPG values for Eimeria spp. and GIS were <1000 eggs/gram feces, tending to be higher in young versus adult goats and in autumn versus spring. FECR (90%CI) values post-AH administration were 38.42 (23.4; 71.8), 54.71 (-4.1; 75.1) for eprinomectin, and 9.78 (-1.7; 64.8) for albendazole, suggesting AH ineffectiveness and AR presence in H1, H2, and H5, respectively. These findings highlight that specific management measures are needed.

The Lipid Composition of the Exo-Metabolome from Haemonchus contortus

Background/Objectives: Metabolomic studies of different parasite-derived biomolecules, such as lipids, are needed to broaden the discovery of novel targets and overcome anthelmintic resistance. Lipids are involved in diverse functions in biological systems, including parasitic helminths, but little is known about their role in the biology of these organisms and their impact on host-parasite interactions. This study aimed to characterize the lipid profile secreted by Haemonchus contortus, the major parasitic nematodes of farm ruminants. Methods: H. contortus adult worms were recovered from infected sheep and cultured ex vivo. Parasite medium was collected at different time points and samples were subjected to an untargeted global lipidomic analysis. Lipids were extracted and subjected to Liquid Chromatography-Mass Spectrometry (LC-MS/MS). Annotated lipids were normalized and subjected to statistical analysis. Lipid clusters' fold change (FC) and individual lipid features were compared at different time points. Lipids were also analyzed by structural composition and saturation bonding. Results: A total of 1057 H. contortus lipid features were annotated, including glycerophospholipids, fatty acyls, sphingolipids, glycerolipids, and sterols. Most of these compounds were unsaturated lipids. We found significant FC differences in the lipid profile in a time-dependent manner. Conclusions: We predict that many lipids found in our study act as signaling molecules for nematodes' physiological functions, such as adaptation to nutrient changes, life span and mating, and as modulators on the host immune responses.

Proteolytic profile and nematicidal potential of proteases produced by Pleurotus djamor in coprocultures

The aim of this study was to evaluate the proteolytic profile of the cell-free crude extract (CFCE) of Pleurotus djamor and its nematicidal action on Haemonchus spp. and Trichostrongylus spp. larvae in coprocultures. Solid-state fermentation was used to produce proteases by P. djamor. The proteolytic and specific activity of CFCE was measured, and its proteolytic profile was revealed using a zymogram. The nematicidal assay of CFCE in coprocultures was evaluated using two groups: the control group (G1) containing 1 mL of CFCE with denatured enzymes +10 g of positive feces, and the treated group (G2) containing 1 mL of active CFCE +10 g of positive feces. For each group, 10 repetitions were carried out. A proteolytic activity of 7.5 ± 0.9 U mL-1 and a specific activity of 30 ± U mg-1 were measured. With regard to the nematicidal assay, there was a significant 35 % reduction in the number of larvae recovered from G2 compared to G1. The zymogram showed the presence of at least two proteases in the active CFCE of P. djamor with molecular weights between 75 and 100 kDa. The results suggest that the CFCE of P. djamor has nematicidal potential even in the feces environment.

A systematic review of the molecular mechanisms related to anthelmintic resistance in Haemonchus contortus: A contemporary narrative

Haemonchus contortus is a gastrointestinal parasite that affects ruminants (cattle, sheep, etc.), having a significant welfare impact worldwide. The rise of anthelmintic resistance poses a growing challenge to adequate control, compromising the success of treatments. This study presents a systematic review of the molecular mechanisms involved in the resistance of H. contortus to anthelmintic drugs. Following an extensive literature search (9075 total articles/excluding duplications), 61 articles were examined. From these, benzimidazoles (BZD) and macrocyclic lactone (ML) were the most reported drug classes (17 and 29, respectively). The mutations in the β-tubulin gene were the primary mechanism of BZD resistance. Important comparisons from early reports of resistance mechanisms to ML (published before 2020) mainly based on parasite-population gene expression (e.g., ligand-gated chloride channels, LGCC, and P-glycoproteins, PGP) with more recent genomic and transcriptomic data (e.g., transcription factor, cky-1 gene) are highlighted. Additionally, resistance mechanisms to levamisole (LEV) and monepantel are discussed, showing evidence of polymorphisms in genes related to the nicotinic acetylcholine receptors (nAChR). Considering the available data, it is possible to divide the reports into two technological periods, evidencing that the availability of a chromosome-level genome for H. contortus in association with experiments based on controlled genetic crosses and transcriptome-wide data allowed for the visualization of genes and polymorphisms that were previously indistinguishable from unrelated genetic variation (i.e., genetic noise). Therefore, the study of anthelmintic resistance mechanisms is facing new possibilities, reflecting the large data banks and the speed at which this information is being processed. We suggest that new publications on drug resistance should adopt the approaches and refer to this new era of scientific discoveries. Consistent data interpretation, including artificial intelligence (AI) support, will help us to suggest novel biological mechanisms involved in drug resistance and predict its evolution, allowing a more comprehensible approach toward sustainable parasite control strategies.

Surveillance of Ancylostoma caninum in naturally infected dogs in Quebec, Canada, and assessment of benzimidazole anthelmintics reveal a variable efficacy with the presence of a resistant isolate in imported dogs

Ancylostoma caninum is a widely prevalent parasitic nematode in dogs across the world. There has been a notable increase in reports of anthelmintic resistance in A. caninum within the United States of America in recent years, which has led us to investigate the potential of this scenario in Canada. The study objectives were to assess the prevalence of A. caninum in two different groups, including a colony of rescued dogs in Canada and three imported Greyhound dogs from USA, and to evaluate the efficacy of two benzimidazole (BZ) anthelmintics against A. caninum, complemented with a molecular genetic analysis adapted to low prevalence. Fecal samples were collected at pre- and post-treatment with fenbendazole for the native shelters-origin group, and a combination of anthelmintic formulations, including the pro-BZ febantel for the USA-origin group. The coprology analyses found several genera of internal parasites. Canine ancylostomiasis was the most prevalent parasitosis with 30.77% in the native group and 100% in the USA group, but with overall low average of A. caninum eggs per gram. Through the fecal egg count reduction test (FECRT), applying a cut-off at 90% as baseline of egg reduction for successful efficacy, BZ showed variable efficacy. Furthermore, molecular analysis confirmed the presence of A. caninum in both groups of dogs and found differences in the genetics linked to BZ resistance on the A. caninum β-tubulin isotype 1 gene. In the isolate from the native group, both codons 167 and 200 were homozygous without the presence of single nucleotide polymorphism (SNP). In contrast, the selected isolate from the USA group, showed a homozygous allele at position 200 and a heterozygous SNP at position 167. The latter was congruent with the low efficacy in FECRT and agrees with the recent findings of USA A. caninum isolate resistant phenotype to the BZ anthelmintics. The limitations of the study include an overall low eggs-per-gram in both canine groups, and the shortage of additional fecal samples from the USA group, restraining the molecular analysis only to one out of the three Greyhounds. This study provided some insights on the efficacy of BZs against A. caninum and revealed the presence of BZ resistant isolates in imported dogs in Quebec, Canada. All this information should be considered, for choosing the best strategy in the control of A. caninum using anthelmintic drugs.

Comparison of traditional copromicroscopy with image analysis devices for detection of gastrointestinal nematode infection in sheep

Sustainable parasite control practices are necessary to combat the negative effects of gastrointestinal nematodes on animal health and production while reducing the selection pressure for anthelmintic resistance. Parasite diagnostic tests can inform treatment decisions, the timing and effectiveness of treatment and enable livestock breeding programmes. In recent years new diagnostic methods have been developed, some incorporating machine learning (ML), to facilitate the detection and enumeration of parasite eggs. It is important to understand the technical characteristics and performance of such new methods compared to long standing and commonly utilised methods before they are widely implemented. The aim of the present study was to trial three new diagnostic tools relying on image analysis (FECPAKG2, Micron and OvaCyte) and to compare them to traditional manual devices (McMaster and Mini-FLOTAC). Faecal samples were obtained from 41 lambs naturally infected with gastrointestinal nematodes. Samples were mixed and separated into 2 aliquots for examination by each of the 5 methods: McMaster, Mini-FLOTAC, FECPAKG2, Micron and OvaCyte. The techniques were performed according to their respective standard protocols and results were collected by trained staff (McMaster and Mini-FLOTAC) or by the device (FECPAKG2, Micron and OvaCyte). Regarding strongyle worm egg count, McMaster values varied from 0 to 9,000 eggs per gram (EPG). When comparing replicate aliquots, both the Mini-FLOTAC and Micron methods displayed similar repeatability to McMaster. However, we found FECPAKG2 and OvaCyte significantly less precise than McMaster. When comparing parasite egg enumeration, significant positive linear correlations were established between McMaster and all other methods. No difference was observed in EPG between McMaster and Mini-FLOTAC or FECPAKG2; however, Micron and OvaCyte returned significantly higher and lower EPG, respectively, compared to McMaster. The number of eggs ascribed to other parasite species was not sufficient for performing a robust statistical comparison between all methods. However, it was noted that FECPAKG2 generally did not detect Strongyloides papillosus eggs, despite these being detected by other methods. In addition, Moniezia spp and Trichuris spp eggs were detected by OvaCyte and Mini-FLOTAC, respectively, but not by other methods. The observed variation between traditional and new methods for parasite diagnostics highlights the need for continued training and enhancing of ML models used and the importance of developing clear guidelines for validation of newly developed methods.

Faecal egg count reduction test in goats: Zooming in on the genus level

The faecal egg count reduction test (FECRT) is the most widely used method to assess treatment efficacy against gastrointestinal nematodes (GIN). Information on genera composition of the GIN community is not available with this test and it is commonly obtained by identifying cultured third-stage larvae (L3) or through molecular assays in the post-treatment survey, but results provided are usually only qualitative or semi-quantitative. The updated WAAVP guidelines now recommend assessing anthelmintic efficacy for each GIN genus/species separately (genus-specific FECRT), but this approach is poorly employed in Europe and in goats especially. For this reason, four FECRT trials were conducted using oxfendazole and eprinomectin in two Italian goat farms. Samples were processed individually using the McMaster technique and then pooled to create two samples from faeces of 5 animals each. Pooled samples were analysed using the McMaster and cultured for seven days at 26°C to obtain L3s. The genus-specific FECRT was based on larval identification, integrating coproculture and FEC results. Larvae were identified as Haemonchus, Trichostrongylus, Teladorsagia, Oesophagostomum / Chabertia and Bunostomum. Molecular assays (a multiplex real-time PCR and two end-point PCRs) were also implemented on pooled samples to support the morphological identification. The Spearmann Rho test confirmed a high correlation between the two approaches (Rho = 0.941 and Rho = 0.914 respectively for Haemonchus and Trichostrongylus, the two most common genera). Both oxfendazole and eprinomectin were effective in one farm, while none in the other farm (FECR = 75.9% and 73.3% respectively). In the second farm, the genus-specific FECRT highlighted a different response to treatment among genera: oxfendazole lacked efficacy against both Haemonchus and Trichostrongylus spp., eprinomectin only against Haemonchus, while all other genera were susceptible to both drugs. This study brings new attention on the importance of adopting a genus-specific approach to identify and quantify differences in susceptibility to anthelmintics among genera in goats, providing support for FECRT interpretation, anthelmintic resistance evaluation and evidence-based GIN control.

Multidrug resistance in Haemonchus contortus in sheep - can it be overcome?

Introduction

Gastrointestinal nematodes pose a threat to animal health and affect farmers by negatively impacting farm management.

Material and Methods

The study was conducted on a sheep farm with suspected reductions in the efficacies of anthelmintics. Efficacy was determined using in vivo faecal egg count reduction, in vitro egg hatch (EHT) and larval development (LDT) tests. In the first phase, 60 sheep were equally split into six groups. Group 1 received the recommended dose of albendazole (ALB), group 2 received the same after fasting for 24 h, group 3 received the dose divided into two halves at 6 h intervals, group 4 received a double dose of ALB, and group 5 received the recommended dose of ivermectin (IVM). Group 6 served as a control. The second phase of the experiment had two groups: one treated with levamisole (LEV) and a control group. Faecal samples were collected from all sheep.

Results

No reduction of egg output was observed in the groups treated with single, double, or divided doses of ALB, but one of 13.7-16.9% was noted in the fasting group. Efficacy in the IVM group ranged from 31.50 to 39.97%. The mean concentrations sufficient to prevent 50% of the eggs from hatching in the in vitro EHT and the mean concentrations in which the development of larvae to the L3 stage was inhibited by 50% in the LDT exceeded established thresholds for benzimidazoles and IVM. Haemonchus contortus was the only species identified after treatment. The LDT did not indicate the presence of resistance to LEV. All animals treated with LEV were negative for eggs 10 d after treatment.

Conclusion

Resistance to ALB and IVM in Haemonchus contortus was confirmed. Alternative approaches to improve the efficacies of benzimidazole did not sufficiently increase the efficacy, but LEV was an efficient anthelmintic treatment.

Research on the Control of Gastrointestinal Strongyles in Sheep by Using Lotus corniculatus or Cichorium intybus in Feed

The general practice of sheep farmers in gastrointestinal helminth control is based on the use of commercial drugs, making chemoresistance very common. Considering this, our study focused on the biological control of gastrointestinal parasitism using high-tannin plant hay. Three groups of 30 animals each were formed. The control group was additionally fed meadow hay, while the other two groups received chicory (group 2) and bird's foot trefoil hay (group 3). The number of gastrointestinal strongyle eggs, shed through faeces (EPG), was surveyed for 28 days for all animals. The amounts of total tannins for meadow, chicory, and Lotus corniculatus hay supplements were 13.92 mg/g, 78.59 mg/g, and 94.43 mg/g, while their condensed tannin contents were 2.58 mg/g, 29.84 mg/g, and 15.94 mg/g, respectively. Compared to experimental day 0, there was an increase in EPG of 80.83% in the control group, a decrease of 24.72% in group 2, and a 20% decrease in group 3, by day 28. The p-value was <0.05 between group 1 and the other groups, showing significant differences between the control and experimental groups. The decrease in EPG rates in the experimental groups compared to the control group demonstrates an antiparasitic effect of Lotus corniculatus and chicory.

[Five past twelve - the resistance situation in small ruminant gastrointestinal nematodes in Germany]

Anthelmintic resistance has reached alarming levels worldwide and already seriously threatens pasture-based small ruminant production in certain geographic regions. The situation in Europe has also dramatically deteriorated in the last decade. This review provides an overview of the occurrence of anthelmintic resistance in small ruminants with a particular focus on Germany and its neighbouring countries. It also covers mechanisms leading to the development and spread of anthelmintic resistance, and recommendations for a responsible use of anthelmintics in veterinary practice.

First report of eprinomectin-resistant isolates of Haemonchus contortus in 5 dairy sheep farms from the Pyrénées Atlantiques département in France

Infection of sheep by gastrointestinal nematodes (GIN) in pastoral systems such as those found in the South Western area of France, the Pyrénées Atlantiques, is one of the main reasons for economic loss and degradation of their welfare. In the present study, the efficacy of eprinomectin (EPN) was monitored on farms from this area following suspicion of lack of anthelmintic efficacy. Suspicions were raised by veterinarians, based on clinical signs ranging from milk and body condition loss, to anaemia, and mortality. Resistance was evaluated according to the World Association for the Advancement for Veterinary Parasitology (WAAVP) guidelines using fecal egg count reduction tests reinforced by individual analysis of drug concentration in the serum of all treated ewes by high-performance liquid chromatography (HPLC). EPN was administered by subcutaneous (SC) and topical (T) route according to manufacturer's requirements, as well as by the oral route (O) with the topical solution according to off-labelled practices in the field. For the first time in France, the presence of resistant isolates of Haemonchus contortus to EPN was observed in 5 dairy sheep farms. The HPLC dosages showed exposure of worms to concentrations compatible with anthelmintic activity for animals treated by the SC and O routes. By contrast, they showed under exposure to the drug of most individuals treated by the T route. EPN is the only null milk withdrawal anthelmintic molecule currently available. The presence of resistant isolates of the pathogenic H. contortus to EPN in this important dairy region requires an urgent change in grazing, and sometimes production, systems.

Variability in the Response against Teladorsagia circumcincta in Lambs of Two Canarian Sheep Breeds

The increasing resistance to anthelmintics has necessitated the exploration of alternative control strategies of gastrointestinal nematode (GIN) infections. A sustainable option is genetic selection based on differences in susceptibility to GIN infection between and within breeds of sheep. Here, three-month-old Canaria Hair breed (GIN-resistant) and Canaria Sheep breed (GIN-susceptible) showed no significant between-breed differences after trickle infection with Teladorsagia circumcincta, whereas considerable individual variability was found in both breeds. Next, data from lambs of both breeds were used to explore the relationships between parasitological variables and T. circumcincta-specific IgA levels, local immune cell populations, and abomasal lymph node gene expression to understand the possible mechanisms underlying resistance. Mucosal IgA levels as well as numbers of globular leukocytes and MHC-II⁺ cells were associated with protection. Analysis of lymph node gene expression revealed the associations between lower parasite numbers and cumulative fecal egg counts and several immune pathways, such as leukocyte cell adhesion, activation and differentiation of T cells, in particular CD4⁺ and IL-4 production. The data obtained here may inform on the relationship between phenotypic resistance variability and protective responses at the humoral, cellular, and transcriptomic levels, thus contributing to identifying immune responses in young lambs that could be used as markers for selection.

Application of multiplex amplicon deep-sequencing (MAD-seq) to screen for putative drug resistance markers in the Necator americanus isotype-1 β-tubulin gene

Global control of hookworm infections relies on periodic Mass Drug Administration of benzimidazole drugs to high-risk groups, regardless of infection status. Mutations in the isotype-1 β-tubulin gene have been identified in veterinary nematodes, resulting in structural changes and reduced drug-binding. In Ghana, previous studies have demonstrated significant variability in albendazole effectiveness among people infected with the hookworm Necator americanus, although the mechanisms underlying deworming response have not been defined. Using hookworm egg samples from a cross-sectional study in Ghana, we developed a multiplex amplicon deep sequencing (MAD-seq) method to screen genomic regions encapsulating putative drug-resistance markers in N. americanus isotype-1 β-tubulin gene. Three single nucleotide polymorphisms (SNPs) corresponding to resistance-associated mutations (F167Y, E198A, F200Y) within the coding region of the isotype-1 β-tubulin gene were characterized using MAD-seq in 30 matched pre- and post-treatment samples from individuals with persistent infection following therapy. Post-sequence analysis showed that the highest mean alternative nucleotide allele at each PCR amplicon was 0.034% (167amplicon) and 0.025% (198/200amplicon), suggesting minimal allelic variation. No samples contained the F167Y SNP, while one contained low-frequency reads associated with E198A (3.15%) and F200Y (3.13%). This MAD-seq method provides a highly sensitive tool to monitor the three putative benzimidazole resistance markers at individual and community levels. Further work is required to understand the association of these polymorphisms to treatment response.

Effectiveness of Anthelmintic Treatments in Small Ruminants in Germany

Simple Summary

Parasitic worms are a major threat to the health and production of sheep and goats worldwide, particularly because many worms have become resistant to commonly applied drugs. This problem is well known around the world, but the situation is currently not well studied in Germany. This study was therefore performed to evaluate the effectiveness of treatments against infection with gastrointestinal nematodes. Faecal samples from animal groups were examined before and after treatment, the worm eggs in the feaces were counted, and the reduction in egg excretion following treatment was calculated. Eggs of Haemonchus contortus (barber’s pole worm) were stained to differentiate them from other gastrointestinal nematodes. Treatments were chosen and carried out by farmers together with their local veterinarian. Additional information was collected by questionnaires to check if the treatments were performed correctly. Reduced effectiveness was observed for all available drugs, but some showed better treatment success than others. The barber’s pole worm frequently survived treatments by most products. The high percentage of treatment failures is highly concerning, and it is necessary to develop and/or apply alternative methods of worm control to prevent the deterioration of this situation.

Abstract

Widespread anthelmintic resistance is a concern for small ruminant health and production worldwide. The current situation regarding anthelmintic efficacy is, however, not very well studied in Germany. Thus, a nationwide field study was undertaken to assess the effectiveness of 253 treatments performed in 223 small ruminant flocks by faecal egg count reduction test (FECRT) using pooled samples and a modified McMaster method. The percentage of Haemonchus contortus and non-Haemonchus eggs was determined by fluorescence microscopy following peanut agglutinin–fluorescein isothiocyanate staining. Treatments were chosen and performed by farmers together with their local veterinarian, and potentially confounding factors for FECRT results were addressed as far as possible by rigorous inclusion criteria. Reduced effectiveness was observed for treatments with all examined anthelmintic classes, but treatments with benzimidazoles and moxidectin showed significantly poorer results than monepantel, a closantel and mebendazole combination, and levamisole. Low case numbers precluded reliable assessment of avermectins. Unsuccessful treatments were frequently associated with the survival of H. contortus, but this was also observed for non-Haemonchus genera. The results are highly concerning, and sustainable approaches to parasite control are urgently needed to prevent further deterioration of this situation.

Increasing resistance to multiple anthelmintic classes in gastrointestinal nematodes on sheep farms in southwest England

Background

Anthelmintic resistance (AR) in gastrointestinal nematodes (GIN) is increasing globally, and farmers are encouraged to adopt sustainable control measures. Haemonchus contortus is increasingly reported in the UK, potentially complicating effective GIN control.

Methods

Faecal egg count reduction tests (FECRT) were conducted on 13 farms in north Devon, England, UK in 2016. Relative abundance of H. contortus was quantified using peanut agglutinin staining and used to estimate faecal egg count reduction percentages (FECR%) using the eggCounts R package.

Results

On average, farms had GIN resistance to three anthelmintic classes. No farms had susceptibility to all anthelmintics tested. AR was more prevalent in 2016 than on the same farms in 2013. H. contortus was present on 85% of the farms tested and comprised on average 6% (0%–52%) of GIN eggs before treatment. Resistance or suspected resistance to all anthelmintics tested was observed in this species on different farms.

Conclusion

The results demonstrate diversity of AR profiles on farms, apparent progression of AR within a 3‐year period, and challenges detecting AR in mixed‐species infections. Where possible, interpretation of mixed‐species FECRT should take into account the relative abundance of species pre‐ and post‐treatment to identify pragmatic treatment options targeting individual genera.

Assessment of Avermectins-Induced Toxicity in Animals

Macrocyclic lactones, particularly the avermectins, have completely revolutionized the approaches aimed at control of parasites. These avermectins are the most widely used anti-parasitic drugs in veterinary field with sales exceeding one billion US dollars annually. However, before clinical usage, their safety evaluation in the animals is a major critical factor that must be considered. Many studies have reported the negative effects of avermectins like ivermectin, abamectin, doramectin, and eprinomectin on the host animals. These harmful effects arise from avermectins targeting GABA and glutamate-gated chloride channels present both in the parasites and the host animals. In this review, various modes of avermectins action along with the negative effects on the host like nephrotoxicity, hepatotoxicity, neurotoxicity, reproductive toxicity, and endocrine disruption were discussed in detail. Furthermore, other important issues like ecotoxicity, drug resistance, and drug residues in milk associated with avermectins usage were also discussed, which need special attention.

Unfavorable genetic correlations between fecal egg count and milk production traits in the French blond-faced Manech dairy sheep breed

Background

Genetic selection has proven to be a successful strategy for the sustainable control of gastrointestinal parasitism in sheep. However, little is known on the relationship between resistance to parasites and production traits in dairy breeds. In this study, we estimated the heritabilities and genetic correlations for resistance to parasites and milk production traits in the blond-faced Manech breed. The resistance to parasites of 951 rams from the selection scheme was measured through fecal egg counts (FEC) at 30 days post-infection under experimental conditions. Six milk production traits [milk yield (MY), fat yield (FY), protein yield (PY), fat content (FC), protein content (PC) and somatic cell score (LSCS)], were used in this study and were collected on 140,127 dairy ewes in first lactation, as part of the official milk recording. These ewes were related to the 951 rams (65% of the ewes were daughters of the rams).

Results

Fecal egg counts at the end of the first and second infections were moderately heritable (0.19 and 0.37, respectively) and highly correlated (0.93). Heritabilities were moderate for milk yields (ranging from 0.24 to 0.29 for MY, FY and PY) and high for FC (0.35) and PC (0.48). MY was negatively correlated with FC and PC (− 0.39 and − 0.45, respectively). FEC at the end of the second infection were positively correlated with MY, FY and PY (0.28, 0.29 and 0.24, respectively with standard errors of ~ 0.10). These slightly unfavorable correlations indicate that the animals with a high production potential are genetically more susceptible to gastrointestinal parasite infections. A low negative correlation (− 0.17) was also found between FEC after the second infection and LSCS, which suggests that there is a small genetic antagonism between resistance to gastrointestinal parasites and resistance to mastitis, which is another important health trait in dairy sheep.

Conclusions

Our results indicate an unfavorable but low genetic relationship between resistance to gastrointestinal parasites and milk production traits in the blond-faced Manech breed. These results will help the breeders’ association make decisions about how to include resistance to parasites in the selection objective.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12711-022-00701-1.

Nematocidal activity of hydroalcoholic extracts of spent substrate of Pleurotus djamor on L3 larvae of Haemonchus contortus

The objective of this study was to evaluate and compare the in vitro lethal effect of the hydroalcoholic extract of the spent substrate of Pleurotus djamor ECS-123, obtained at 15 days of colonization (SPS) and at the first (SPS1) and second (SPS2) harvests, against infective larvae L₃ of Haemonchus contortus. The in vitro lethal effect was evaluated by the L₃ larval mortality test (LM) using six concentrations: 1.25, 2.5, 5, 10, 20, and 40 mg/mL, with ivermectin and thiabendazole (5 mg/mL) as controls. The first harvest extract (SPS1) of strain ECS-123 was subjected to liquid-liquid bipartition, which resulted in two fractions: aqueous (PdAcO) and ethyl acetate (PdAct). The chemical fractionation of PdAct with the highest mortality rate (80.11 %) was carried out with open-column chromatography, giving a total of 13 fractions, which were analyzed by thin-layer chromatography (TLC) and grouped into 5 mixtures (R1;1-3, R2;4-7, R3;8-9, R4;10-11 and R5;12-13). Subsequently, the mixtures were evaluated against H. contortus L₃ larvae. Finally, the components of the mixtures with the highest nematocidal effects were evaluated by gas chromatography coupled to mass spectrometry (GC-MS). The data were analyzed with a completely randomized design through ANOVA using the generalized linear model (GLM) with the "R" program. The purification and characterization of R4 and R5 by GC-MS revealed the presence of the following compounds: veratryl alcohol, 4-hydroxy-3,5,5 trimethyl-4-[3-oxo-1-butenyl]-2- cyclohexen-1-one, caffeine and 5,6-dimethoxy-1(3 H) isobenzofuranone. This information allowed for the identification of nematocidal compounds in the degraded substrate of P. djamor, an activity that had not been reported previously.

Pour-on administration of eprinomectin to lactating dairy goats: Pharmacokinetics and anthelmintic efficacy

Lactation is discussed as a physiological covariate which may influence the exposure characteristics of systemically acting drugs including macrocyclic lactones and potentially alter their pharmacological response. This study characterizes for the first time in the same study, the plasma profile and therapeutic anthelmintic efficacy of eprinomectin 5 mg/ml solution (EPRINEX^® Multi, Boehringer Ingelheim) administered as a pour-on at 1 mg per kg body weight to lactating dairy goats. The study was conducted in compliance with VICH GCP and anthelmintic efficacy evaluation guidelines and included 20 goats harboring induced adult gastrointestinal and pulmonary nematode infections. The goats were blocked on pre-treatment body weight and randomly allocated either to remain untreated (control) or to be eprinomectin-treated. Plasma samples to determine the plasma disposition kinetics of eprinomectin (B1a component) were obtained at intervals up to 14 days following treatment when the animals were necropsied for parasite enumeration and identification. Basic pharmacokinetic parameters of eprinomectin determined in the ten eprinomectin-treated goats were as follows: AUC_last , 23.8 ± 9.7 day*ng/ml and C_max , 5.35 ± 2.27 ng/ml; individual maximum plasma concentrations were observed from 8 to 48 h after treatment (median T_max , 0.5 days). Topical eprinomectin treatment efficacy, based on significant (p < .01) worm burden reductions in eprinomectin-treated animals relative to untreated controls, was ≥97% to 100% against adult Dictyocaulus filaria, Haemonchus contortus, Teladorsagia circumcincta(pinnata/trifurcata), Trichostrongylus axei, T. colubriformis, Cooperia curticei, Nematodirus battus, and Oesophagostomum venulosum. Both pharmacokinetic parameters and anthelmintic activity in lactating dairy goats were similar to those observed in parasitized young growing and adult female non-lactating dairy goats treated with eprinomectin administered as a pour-on.

Resistance of strongylid nematodes to anthelmintic drugs and driving factors at Czech goat farms

Background

Strongylid nematode infections may negatively affect both animal health and welfare, with deleterious consequences for livestock productivity. Many farmers in recent decades have relied on anthelmintics as the sole strategy of control, but the intensive use of these chemotherapeutics has led to the development of anthelmintic resistance (AR). Knowledge of both the efficacy of anthelmintics and factors promoting AR are essential to effectively control nematode infections, but no information on these topics for goats in the Czech Republic (CR) is available. This survey aimed to determine the occurrence of AR at Czech goat farms and to identify risk factors for the development of AR. A total of 24 herds of dairy goats across the CR were evaluated using in vitro tests for detecting AR, and a questionnaire survey was carried out to evaluate factors associated with AR.

Results

Resistance against benzimidazoles was confirmed at 18 (75%) farms, and the level of resistance was high in four (22%) of the affected herds based on the egg hatch test. Ivermectin-resistant nematodes were detected in 13 (54%) herds using the larval development test; Teladorsagia/Trichostrongylus and Haemonchus were the predominant types of resistant larvae. Eight (62%) of the affected herds were evaluated as highly resistant to ivermectin. Eleven (46%) of the herds were resistant to both benzimidazoles and ivermectin. This report is the first on dual AR in the CR. A univariate logistic regression analysis indicated that a high stocking rate and farmer inexperience were significantly associated with ivermectin and benzimidazole resistance, respectively.

Conclusions

The results of our survey suggest that AR is widespread amongst herds of dairy goats in the CR, likely due to inappropriate practices of pasture and health management. AR may be an issue for expanding dairy-goat production in the CR in the near future unless both veterinary practitioners and farmers widely adopt strategies to prevent the development of AR.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12917-021-02819-8.

Effect of injectable eprinomectin on milk quality and yield of dairy ewes naturally infected with gastrointestinal nematodes

The objective was to investigate the effect of injectable eprinomectin on milk yield and quality of dairy ewes naturally infected with gastrointestinal nematodes when grazing in communal pastures. Onehundred and fifty (150) clinically healthy adult lactating ewes, equally selected from 3 farms, were included in the study. On day -7, the ewes on each farm were randomly allocated into 2 equal groups of 25 animals (n=50): Control group (C) and Treated group (T). On day 0, ewes in group T were given a single subcutaneous injection of eprinomectin at a dose rate of 0.2 mg/kg bodyweight. Ewes in group C were left untreated during the whole experiment. Ewes in group T with a fecal egg count (FEC) >300 eggs per g on day +60 were treated again. Fecal samples were individually collected on days -7, 0, +30, +60, +90, +120 for FEC estimations and coprocultures. On days -7, 0, +30, +60 and +90, individual milk yield (MY) was recorded using ICAR approved volumetric milk meters. Energy corrected milk yield (ECMY) for 6% fat was also calculated. Moreover, individual milk samples were collected on each day for determination of chemical composition [fat (F%), protein (P%) and lactose (L%) content] and somatic cell counts (SCC). On each day, individual fat and protein yield (FY and PY, respectively) were calculated. Total lactation MY, total ECMY, total FY and total PY were computed. The most prevalent parasite at pre-treatment and post-treatment days was Haemonchus spp. The overall efficacy on days +30 and +90 was 97.27 % and 98.80 %, respectively. In two out of the three farms, 80 % and 91.3 % of T ewes received a second treatment on day +60, due to high parasitic burden. Treatment had a significant effect (P=0.033) on MY with an average benefit of 8%. No significant effects of treatment were observed on the other parameters, although values were constantly numerically higher for treated ewes compared to control ones. In this field trial, injectable eprinomectin had a high overall efficacy and a beneficial effect on daily milk yield.