Gastrointestinal Nematodes Of Sheep Research Articles

Epidemiology and field efficacy of anthelmintic drugs associated with gastrointestinal nematodes of sheep in Nejo district, Oromia, Ethiopia

Gastrointestinal nematodes (GINs) are major constraints to health and productivity of small ruminants. Methods of their control relies mainly on anthelmintic drugs; however, the indiscriminate use of these drugs could lead to the development of anthelmintic resistance (AR). This study aimed to investigate the epidemiology of GINs infection, and field evaluation of anthelmintic efficacy in sheep. The epidemiological data were collected using a cross-sectional study design while a farm-based field study design was employed for the evaluation of anthelminthic efficacy. Furthermore, standard parasitological techniques were employed for qualitative and quantitative worm identification. The overall prevalence indicated 50.3%. Six genera of GINs (Haemonchus, Trichostrongylus, Oesophagostomum/Chabertia, Trichuris, Teladosargia/Ostertagia and Nematodirus) were identified. Among the identified genera, Haemonchus (25.4%) and Trichostrongylus (24.8%) were the dominant genera followed by mixed infection (21.8%), Oesophagostomum/Chabertia (10.4%), Trichuris (7.8%), Teladosargia (Ostertagia) (5.7%) and Nematodirus (4.1%). Mixed infections consisted either of double infections with Haemonchus and Trichostrongylus, or triple infections with Haemonchus, Trichostrongylus and Trichuris. The McMaster egg counting results showed that the mean EPG of infected sheep was 845.6. The results also showed 66 (34.2%), 101 (52.3%) and 26 (13.5%) sheep had low, moderate and heavy worm burden, respectively. Albendazole and Ivermectin showed low efficacy (percentage reductions = 90% and 92%; 95% lower confidence limit = 82.1% and 83.6% respectively) whereas Tetramisole was effective (FECR% = 96.8%; 95% LCL = 93.4%). Factors such as age, body condition, management system and past deworming history of sheep were found to have a statistically significant (p < 0.05) influence on the occurrence and burden of the worms. This is further explained as the highest prevalence and worm burden was detected in sheep of young age (p = 0.008; OR = 0.58; 95% CI = 0.39–0.87), poor body condition (p = 0.001; OR = 0.08; 95% CI = 0.04–0.16) and sheep kept under semi-intensive (p = 0.04; OR = 1.53; 95% CI = 1.02–2.29) with no deworming history for the last two months (p = 0.001; OR = 2.97; 95% CI = 1.94–4.56). The study results revealed that nematode infections were among sheep health constraints that could hurt their productivity while low efficacy of Albendazole and Ivermectin were detected. Therefore, the appropriate management techniques of GIN infections should be designed and implemented. Moreover, a further study involving more sensitive techniques (e.g. Mini-FLOTAC, molecular, and serological techniques) should be conducted by considering different host and environmental risk factors such as production level and seasons.

Genetic Parameter Estimation and Selection for Resistance to Gastrointestinal Nematode Parasites in Sheep-A Review.

Gastrointestinal nematodes (GINs) are a major problem affecting sheep production systems worldwide. The flocks infected with GINs can undergo significant economic losses due to a decrease in productivity, the animals' deaths, and the costs associated with treatments. The over-reliance on anthelmintics in the past years to eliminate GINs has resulted in the development of resistance against the available commercial anthelmintics. Genetically resistant animals can be used in mating systems to improve the overall flock resistance. This review aimed to summarize the estimated genetic parameters for resistance traits and genetic gains through the use of genetic/genomic selection for resistance to GINs in sheep. Heritability estimates from the literature ranged from 0.00 to 0.46 for fecal egg counts, 0.12 to 0.37 for packed cell volume/hematocrit, 0.07 to 0.26 for FAffa MAlan CHArt (FAMACHA©), from 0.10 to 0.37 for blood parameters, and 0.19 for Immunoglobulin A. Genetic correlations between traits measuring resistance to GINs and production traits ranged from negative to positive values in the literature. Genetic gains are possible when genetic/genomic selection for GIN resistance is applied. Therefore, genetic/genomic selection can be used to improve flocks' resistance to GINs as a sustainable approach in sheep production systems.

Effect of pomegranate (Punica granatum) anthelmintic treatment on milk production in dairy sheep naturally infected with gastrointestinal nematodes.

Anthelmintic drug resistance has proliferated across Europe in sheep gastrointestinal nematodes (GINs). Sheep welfare and health are adversely impacted by these phenomena, which also have an impact on productivity. Finding alternatives for controlling GINs in sheep is thus of utmost importance. In this study, the anthelmintic effectiveness (AE) of a Calabrian ethnoveterinary aqueous macerate based on Punica granatum (whole fruits) was assessed in Comisana pregnant sheep. Furthermore, an examination, both qualitative and quantitative, was conducted on milk. Forty-five sheep were selected for the investigation. The sheep were divided by age, weight, physiological state (pluripara at 20 days before parturition), and eggs per gram of feces (EPG) into three homogeneous groups of 15 animals each: PG received a single oral dosage of P. granatum macerate at a rate of 50 mL per sheep; AG, treated with albendazole, was administered orally at 3.75 mg/kg/bw; and CG received no treatment. Timelines were as follows: D0, treatments, group assignment, fecal sampling, and AE assessment; D7, D14, D21, fecal sampling, and AE evaluation. The FLOTAC technique was used to evaluate the individual GIN fecal egg count (FEC) using a sodium chloride flotation solution (specific gravity = 1.20) and 100 × (1-[T2/C2]) as the formula for evaluating FEC reduction. Following the lambs' weaning, milk was collected on the following days (DL) in order to quantify production: DL35, DL42, DL49, DL56, DL63, DL70, DL77, and DL84. The amount of milk produced by every animal was measured and reported in milliliters (ml) for quantitative evaluations. Using MilkoScan TM fT + foss electric, Denmark, the quality of the milk (casein, lactose, protein concentration, and fat, expressed as a percentage) was assessed. The macerate demonstrated a considerable AE (51.8%). Moreover, its use has resulted in higher milk production rates quantitatively (15.5%) and qualitatively (5.12% protein, 4.12% casein, 4.21% lactose, and 8.18% fat). The study showed that green veterinary pharmacology could be the easiest future approach to counteracting anthelmintic resistance in sheep husbandry.

Multi-scale habitat modeling framework for predicting the potential distribution of sheep gastrointestinal nematodes across Iran’s three distinct climatic zones: a MaxEnt machine-learning algorithm

Ecological niche models (ENMs) serve as valuable tools in assessing the potential species distribution, identifying crucial habitat components for species associations, and facilitating conservation efforts. The current study aimed to investigate the gastrointestinal nematodes (GINs) infection in sheep, predict and analyze their ecological niches and ranges, and identify the key bioclimatic variables influencing their distribution across three distinct climatic regions in Iran. In a cross-sectional study, a total of 2140 fecal samples were collected from semi-arid (n = 800), arid (n = 500), and humid-subtropical (n = 840) climates in East Azerbaijan, Kerman, and Guilan provinces, respectively. The flotation method was employed to assess stool samples, whereby the fecal egg count (the number of parasite eggs per gram [EPG]) was ascertained for each individual specimen. Employing a presence-only approach, the multi-scale maximum entropy (MaxEnt) method was used to model GINs' habitat suitability using 93 selected points/locations. The findings revealed that Guilan (34.2%) and East Azerbaijan (19.62%) exhibited the utmost proportion of Strongyle-type eggs. East Azerbaijan province also displayed the highest proportion of Marshallagia and Nematodirus, respectively (approximately 40% and 27%), followed by Guilan and Kerman provinces, while Kerman province had the highest proportion of Trichuris (approximately 15%). Ecological niche modeling revealed that the precipitation of the driest quarter (Bio17) exerted the most significant influence on Marshallagia, Nematodirus, Trichuris, and ُSُُُtrongyle-type eggs' presence in East Azerbaijan and Kerman provinces. For Guilan province, the most influential factor defining habitat suitability for Strongyle-type eggs, Marshallagia, and Nematodirus was increasing slope. Additionally, the distribution of Trichuris was most affected by the variable Bio2 in Guilan province. The study highlights the response of GINs to climate drivers in highly suitable regions, providing insights into ecologically favorable areas for GINs. In conclusion, this study provides a better understanding of GINs and the environmental factors influencing their transmission dynamics.

Genomic Regions Associated with Resistance to Gastrointestinal Nematode Parasites in Sheep-A Review.

Gastrointestinal nematodes (GINs) can be a major constraint and global challenge to the sheep industry. These nematodes infect the small intestine and abomasum of grazing sheep, causing symptoms such as weight loss, diarrhea, hypoproteinemia, and anemia, which can lead to death. The use of anthelmintics to treat infected animals has led to GIN resistance, and excessive use of these drugs has resulted in residue traced in food and the environment. Resistance to GINs can be measured using multiple traits, including fecal egg count (FEC), Faffa Malan Chart scores, hematocrit, packed cell volume, eosinophilia, immunoglobulin (Ig), and dagginess scores. Genetic variation among animals exists, and understanding these differences can help identify genomic regions associated with resistance to GINs in sheep. Genes playing important roles in the immune system were identified in several studies in this review, such as the CFI and MUC15 genes. Results from several studies showed overlapping quantitative trait loci (QTLs) associated with multiple traits measuring resistance to GINs, mainly FEC. The discovery of genomic regions, positional candidate genes, and QTLs associated with resistance to GINs can help increase and accelerate genetic gains in sheep breeding programs and reveal the genetic basis and biological mechanisms underlying this trait.

Identification of genomic regions associated with resistance to gastrointestinal parasites in an indigenous sheep by single- and multiple-locus methods.

We investigated the association between 157 SNPs located in 75 candidate genes involved in the immune system and proxy traits for resistance to gastrointestinal nematodes in sheep. A total of 211 lambs from eight flocks were sampled. Nematode eggs per gram were counted and classified as: (i) Strongyles, (ii) Nematodirus spp., (iii) Trichuris spp. and (iv) Marshallagia marshalli. Single- and multiple-locus models were used to test the marker-trait associations. Seven significant SNPs were identified on chromosomes OAR6, 15, 16, and 19. These findings provide insights for breeding nemarode-resistant traits in low-input production systems. General linear model, fixed and random model circulating probability unification, and Bayesian-information and linkage-disequilibrium iteratively nested keyway analyses identified a significant association between the eggs per gram of Strongyles nematodes and a specific variant of the PRLR gene.

Candidate Gene Analysis of Genetic Resistance to Gastrointestinal Nematodes in Sheep Through Association of Single Nucleotide Polymorphism with Phenotypic Traits

Background: A study was executed to analyze the genetic resistance to gastrointestinal nematodes through the association of single nucleotide polymorphism markers in Toll-like receptor genes with phenotypic indicator traits in Kilakarsal and Vembur sheep breeds. Methods: The phenotypic traits for analyzing the gastrointestinal nematode infection namely FEC, change in PCV and change in body weight were recorded. The SNP markers in TLR3, TLR5, TLR6, TLR9 and TLR10 genes were employed for genotyping. Competitive allele-specific PCR-based endpoint genotyping was used to type the SNPs. The gene and genotype frequencies were estimated by using the PEAS software program. A complete fixed effects model was utilized for analysis of the association of various genotypes at each SNP with phenotypic indicator traits. Result: The global minor allele frequency of different polymorphic SNP loci ranged from 0.06 to 0.48 with a mean of 0.23, signifying their fitness for the association study. The effect of the farm had no significant influence on FEC and change in body weight, however, had a significant effect on change in PCV (P less than 0.05). No significant difference was detected between the sexes with FEC, change in PCV and change in body weight. The TT genotype in the TLR9_1769_CT locus showed the lowest least-squares mean FEC. The remaining 22 SNP loci showed no significant difference (P greater than 0.05) with mean FEC. Association of 23 TLR SNP genotypes with change in PCV and change in body weight revealed no significant effect (P greater than 0.05).

Genome-enabled prediction of indicator traits of resistance to gastrointestinal nematodes in sheep using parametric models and artificial neural networks

This study aimed to assess the predictive ability of parametric models and artificial neural network method for genomic prediction of the following indicator traits of resistance to gastrointestinal nematodes in Santa Inês sheep: packed cell volume (PCV), fecal egg count (FEC), and Famacha© method (FAM). After quality control, the number of genotyped animals was 551 (PCV), 548 (FEC), and 565 (FAM), and 41,676 SNP. The average prediction accuracy (ACC) calculated by Pearson correlation between observed and predicted values and mean squared errors (MSE) were obtained using genomic best unbiased linear predictor (GBLUP), BayesA, BayesB, Bayesian least absolute shrinkage and selection operator (BLASSO), and Bayesian regularized artificial neural network (three and four hidden neurons, BRANN_3 and BRANN_4, respectively) in a 5-fold cross-validation technique. The average ACC varied from moderate to high according to the trait and models, ranging between 0.418 and 0.546 (PCV), between 0.646 and 0.793 (FEC), and between 0.414 and 0.519 (FAM). Parametric models presented nearly the same ACC and MSE for the studied traits and provided better accuracies than BRANN. The GBLUP, BayesA, BayesB and BLASSO models provided better accuracies than the BRANN_3 method, increasing by around 23% for PCV, and 18.5% for FEC. In conclusion, parametric models are suitable for genome-enabled prediction of indicator traits of resistance to gastrointestinal nematodes in sheep. Due to the small differences in accuracy found between them, the use of the GBLUP model is recommended due to its lower computational costs.

Essential oils against gastrointestinal nematodes in sheep in vitro and chemical composition of those plants

The present study aimed to evaluate the in vitro potential of aromatic plants Aloysia triphylla (cidró ou erva-luísa), Corymbia citriodora (eucalipto-limão), Lippia alba (falsa-melissa) e Piper gaudichaudianum (pariparoba), in helminths eggs and larvae, determine their main constituents. For this, the essential oils (OEs) of the plants were extracted from leafs, in the clevenger apparatus and to determine the main constituents was carried out the gas chromatography coupled to mass spectrometry. The Egg eclodibility assay (EEA) and Larval development test (DLT) were performed using essential oils at concentrations ranged from 75 at 0.2%. mg.mL, and all tests followed by commercial anthelmintic positive control and negative control distilled water. For EEA, A. triphylla e L. alba OEs demonstred equivalente efficacy to the commercial drug at all concentrations that was tested, while P. gaudichaudianum OE demonstred equivalente efficacy at 15 mg/mL and the C. citriodora OE at 10 mg/mL. About DLT, all concentratios of the studied essential oils were effective as the comercial drug results in this test. The dominant constituent in OEs were: geraniale (A. triphylla), citronellal (L. alba), linalool (L. alba) and α-humuleno (P. gaudichaudianum). Based on the results presented here, the OEs present potential for use as natural anthelmintics for the treatment of endoparasitosis in sheep.

Evaluation of the efficacy of solid dispersion of fenbendazole against different stages of gastrointestinal nematodes of sheep in Samara region

The purpose of the research is to study the efficacy of a solid dispersion of fenbendazole at different stages of gastrointestinal nematodes of young sheep. Materials and methods. Evaluation of the efficacy of a solid dispersion of fenbendazole at different stages of gastrointestinal nematodes was carried out in the farms of the Samara region on 35 sheep aged 7–10 months naturally infected with gastrointestinal strongylates. Animals were divided into experimental and control groups of 8-9 animals each. A solid dispersion of fenbendazole was administered once orally at a dose of 2.0 mg/kg of active substance to the animals of the first experimental group. Animals of the 2nd group received the substance of fenbendazole at a dose of 2 mg/kg. The basic drug – Panakur was administered to the sheep of the 3rd experimental group at a dose of 5 mg/kg. Animals of the control group did not receive the drugs. The efficacy of the drugs was calculated in the experiment of «control test» based on the results of coproovoscopic examination, as well as on the results of helminthological necropsy of the digestive tract of animals, 3–5 sheep from each group. Results and discussion. The solid dispersion of fenbendazole showed 97.8–98.2% efficacy against adult strongylates and 80.6–87.5% against larvae. The substance of fenbendazole at the same dose – 2 mg/kg revealed 33.0–41.7% and 16.1–26.9% efficacy respectively. The basic drug Panakur showed 95.4–97.3% and 46.7–73.9% efficacy against imaginal strongylates and larvae respectively at a dose of 5.0 mg/kg of active substance.

Gastrointestinal nematodes in sheep and their anthelmintic resistance. A subject under discussion in Mexico

Gastrointestinal nematodes in sheep and their anthelmintic resistance. A subject under discussion in Mexico

Invitro and in vivo anthelmintic efficacy of peppermint (Mentha x piperita L.) essential oil against gastrointestinal nematodes of sheep.

Nowadays, the exclusive use of commercial anthelmintics for the treatment of gastrointestinal nematode infections in ruminants is less sustainable due to anthelmintic resistance, as well as the problem of drug residues in animal products and the environment. Therefore, an integrated therapeutic approach is needed, including the search for alternatives to synthetic anthelmintic drugs. The aim of this study was to evaluate the possibility of using the essential oil of peppermint (Mentha x piperita L.) in the control of gastrointestinal nematodes in sheep. For this purpose, the in vitro and in vivo anthelmintic efficacy of this oil and the toxic effects on the hosts were examined. In the in vitro egg hatch test, ovicidal activity varied from 21.0-90.3% depending on the concentration of essential oil used (0.0125, 0.025, 0.049, 0.195, 0.781, 3.125, 12.5, and 50 mg/mL). To some extent, anthelmintic efficacy was confirmed in the in vivo fecal egg count reduction test at a mean dose of 150 mg/kg, with an average reduction of nematode eggs of 26.9 and 46.0% at Days 7 and 14 after treatment, respectively. Furthermore, no toxic effects of applied oil were observed on sheep behavior, kidney, or liver function. The main compounds identified by gas chromatography-mass spectrometry analyzes were menthol (32.6%), menthone (22.0%), menthyl-acetate (10.0%), and isomenthone (9.39%). Due to their complex chemical compositions, numerous bioactive ingredients, and natural origin, herbal formulations represent a potentially valuable alternative for the control of gastrointestinal nematodes in sheep. In this context, the results of the present study showed that peppermint essential oil is one of the promising candidates. Further studies should be performed to collect more data on the safety profile of M. piperita EO in treated animals to find the most appropriate formulation for use in field conditions and to test it against resistant gastrointestinal nematode populations.

Anthelmintic Activity of Tanacetum vulgare L. (Leaf and Flower) Extracts against Trichostrongylidae Nematodes in Sheep In Vitro.

Due to the high prevalence of gastrointestinal nematodes in sheep, the growing anthelmintic resistance, and the development of organic farming systems, sustainable alternatives are being sought. One such method is phytotherapy. This study aimed to evaluate the in vitro ovicidal and larvicidal activity of extracts of tansy (Tanacetum vulgare L.) growing in Latvia on gastrointestinal nematodes (Trichostrongylidae) in sheep. The leaves and flowers of the tansy were extracted separately in 70%, 50%, and 30% ethanol and acetone. Six concentrations were prepared from each extract 500 mg/mL, 200 mg/mL, 100 mg/mL, 50 mg/mL, 20 mg/mL, and 10 mg/mL. In vitro egg hatching test and micro-agar larval development test were performed. Extracts of tansy have strong larvicidal activity. The highest percentage of larvae inhibition for most of the extracts was 100%, but for egg inhibition, it was 95.8% for the 200 mg/mL concentration of 50% acetone and 93.3% for the 500 mg/mL concentration of 50% ethanol leaf extracts. All tansy extracts had ovicidal and larvicidal activity against Trichostrongylidae in sheep.

To the fauna of gastrointestinal nematodes of sheep in the European part of Russia

The purpose of the research is to study the fauna of gastrointestinal nematodes of sheep in the European part of the Russian Federation.Materials and methods. The studies were carried out in 2022–2023. The objects for the study were the sets of the gastrointestinal tracts of sheep aged from one to 2.5 years, delivered to the slaughterhouse in the Moscow region from different regions of the Russian Federation, including the Oryol and the Astrakhan regions, the Republic of Dagestan and Stavropol Krai. After slaughter, 10 sets of gastrointestinal tracts were taken by the random sampling method from each batch of delivered sheep. Then, these sets of gastrointestinal tracts were subjected to helminthological necropsy according to the method of K. I. Skryabin (1928). The species of detected nematodes were identified according to K. I. Skryabin et al. (1952) and V. M. Ivashkin et al. (1989).Results and discussion. A different degree of gastrointestinal nematodes infection of sheep has been established in different regions of the European part of the Russian Federation. Thus, the rate of infection in the Oryol region was 80%, in the Astrakhan region – 100%, in the Republic of Dagestan – 100% and in Stavropol Krai – 50%. Sheep were infected with Trichostrongylus colubriformis and Teladorsagia circumcincta with an intensity of infection, on average, 251.86±25.2 and 99.25±9.9 ex./head respectively in the Oryol region; T. colubriformis (242.65±24.3 ex./head), T. circumcincta (76.6±7.7 ex./head.), Haemonchus contortus (6.5±0.7 ex./head) and Marshallagia marshalli (19±1.9 ex./head) in the Astrakhan region; T. colubriformis (89.7±9 ex./head), T. circumcincta (43.6±4.4 ex./head), H. contortus (6.8±0.7 ex./head) and M. marshalli (17.8±1.8 ex./head) in the Republic of Dagestan; T. colubriformis (20.2±2 ex./head) and T. circumcincta (11±1.1 ex./head) in Stavropol Krai. Thus, T. colubriformis and T. circumcincta were the most frequently found nematodes in sheep in all of the four studied regions, and these two species also showed the highest rates of infection. The noted low species diversity of nematodes is obviously associated with the mandatory use of anthelmintic drugs. The studied sheep were treated against parasites (according to the accompanying veterinary documentation). At the same time, the detection of nematodes in treated animals possibly indicates the presence of resistant strains.

NOVEL STRATEGIES FOR THE CONTROL OF GASTROINTESTINAL NEMATODES IN SHEEP

Gastrointestinal nematodes are very important parasites of domestic animals, especially in small ruminants. In sheep, diseases usually have a subclinical form with a decrease in body weight and production, and sometimes there can be visible clinical symptoms such as anorexia, anemia, severe diarrhea and protein loss, all of which together can lead to death. Commercial drugs such as benzimidazole and macrocyclic lactones have been successfully used for decades to control these parasites. However, the irrational application of these drugs has led to the development of anthelmintic resistance, a decrease in their effectiveness and consequent economic losses that threaten the sustainability of sheep breeding. In addition, the use of commercial preparations is also associated with the residues in animal products and the environment, and there is also an increase in the price of these preparations. For this reason, novel strategies for controlling of these parasites are actively seeking, with the goal of establishing an integrated approach that involves the application of several different strategies. On the one hand, these include strategies for the rational application of commercial preparations based on refugia (targeted treatments, targeted selective treatments), as well as the combination and rotation of anthelmintics from different chemical groups. On the other hand, an integrated approach implies the use of different alternative strategies such as genetic selection of animals naturally resistant to nematodes, rational management of pastures, balanced nutrition with supplementary nutrients, biological control (use of fungi, bacteria, etc.), development of vaccines as well as the use of botanical preparations (plants and their products such as extracts and essential oils). Various studies have proven the effectiveness of the mentioned strategies in the control of gastrointestinal nematodes of sheep, whereby the best results are achieved by their combined application. Thus, it is possible to slow down the development and spread of anthelmintic resistance, as well as achieve sustainable control of these parasites and reduce economic losses.

Use of perennial plants in the fight against gastrointestinal nematodes of sheep

BackgroundGastrointestinal nematodes (GINs) are a serious problem in ruminant pastures worldwide. They generate production losses, from the point of view of both the food chain and animal mortality. This study provides preliminary results concerning the use of pasture plants in the Campania region (of southern Italy) to control GINs in sheep.MethodsSixteen species of wild and cultivated perennial plants present in seminatural pastures were sampled. All species were extracted with the conventional maceration technique, using three different solvents (i.e., H2O, EtOH, and an EtOH:H2O (8:2) mixture) in order to extract different bioactive compounds. The total phenolic content (TPC; assessed via the Folin–Ciocȃlteu assay) of all extract samples was preliminarily characterized. Each sample was aliquoted across six different concentrations and an in vitro egg hatching test (EHT) was conducted to evaluate the ovicidal effect on sheep GINs.ResultsThe results indicated that Cichorium intybus L. and Foeniculum vulgare Mill. extracts greatly inhibited egg hatching within 48 hours of exposure, showing efficacy (≥ 62.6%) at the three higher concentrations when compared with the other plants.ConclusionThe use of extracts of wild and cultivated perennial plant species in pastures can be a valid alternative to the use of synthetic anthelmintic drugs, which can generate problems, such as anthelmintic resistance, in the long term. Looking forward, further in vitro studies that evaluate the in vitro effect of these extracts on ruminant cell cultures, and field application through in vivo studies, would likely confirm the results obtained from preliminary in vitro EHTs. All these studies should be aimed at evaluating the therapeutic potential and future applicability of specific plant cultures in pastures to achieve sustainable pest control.

Guide to advances in the control of gastrointestinal roundworms in sheep

Background: In the UK, diseases caused by gastrointestinal nematodes (GINs) are the most expensive endemic diseases, being a major cause of morbidity, mortality and lost production in sheep flocks. Control is complicated by the increasing prevalence of anthelmintic resistance in the GIN population and changes in epidemiology, partially driven by climate change. Therefore, there is great emphasis among sheep farmers and veterinarians to find methods to successfully control GINs and prevent associated diseases.Aim of the article: This article outlines the different strategies that can be implemented on farm to try and sustainably control parasitic gastrointestinal nematodes of sheep.

Nematophagous fungi and their influences on parasitic control in sheep

Infections caused by gastrointestinal nematodes in sheep have become a recurring problem due to the difficulty of eradicating these parasites from the environment. The use of alternative methods, such as biological control, using nematophagous fungi, is a suitable tool for producers. The objective of this review is to provide information, disseminate knowledge, and clarify doubts. Nematophagous fungi are microorganisms adapted to survive in the soil of various cultures, feeding on present, infectious, or free-living larvae, which can also be harmful. In this work, the groups and genera of interest in the context of nematodes were compiled, dividing them according to the mode of action. It is important to note that, under appropriate circumstances, the functioning of the nematophagous fungi may be impaired, even in the presence of proven larvae. Despite the numerous applications for the use of these microorganisms, the work points out some aspects, such as temperature and humidity, as determining factors. The described study concludes the different types and genera of fungi, modes of action, predation, colonization, and habits, facilitating understanding. Some difficulties need to be overcome, such as climatic variations, lack of prey, and their misuse, which it is up to the interested researcher to manipulate.

Evaluation of a combination of Citrus aurantium var. Dulcis essential oil and albendazole for the treatment of sheep gastrointestinal nematodes

Citrus fruits are consumed all over the world and their by-products are used for animal feed and essential oils production. This study aimed to evaluate the in vitro and in vivo activity of Citrus aurantium var. Dulcis essential oil (CaEO) combined with ABZ against benzimidazole resistant Haemonchus contortus. In vitro egg hatching assays (EHA) were performed using CaEO and ABZ to estimate the effective concentration to achieve 50% egg death (EC50) values and calculate the test essential oil and drug combinations using a simplex-centroid mixture design. These concentrations were used for a second round of EHAs. Sixteen sheep were randomly allocated into two groups and treated with ABZ and the combination of CaEO and ABZ, and faecal egg count reduction tests were performed. In the first round of EHA, CaEO and ABZ showed EC50 values of 0.57 and 0.0048 mg mL−1, respectively. The H. contortus strain used in the study was shown to be highly benzimidazole resistant, with only 1.5% of parasites having susceptible ß-tubulin SNP genotypes. The ABZ reduced the shedding of nematode eggs by 78%, however, its combination with CaEO reduced faecal egg counts by only 9%. The present study is important to highlight the interferences of natural products in anthelmintic metabolism and consequently in drug efficacy.

Interaction networks and pathway analysis of genetic resistance to gastrointestinal nematodes in sheep.

Gastrointestinal nematode (GINs) infections are one of the causative agents of health and economic issues in sheep production systems worldwide. Considerable genetic variations in resistance or susceptibility in different sheep breeds are documented, but published results are conflicting. Recent advances obtained by high-throughput technologies such as commercial SNP chips, whole-genome sequencing, or whole transcriptome profiling provide new insights into breeding for host resistance or nematode control at the genetic levels. This study aimed to identify potential biomarkers associated with the resistance to ovine GINs through a network analysis approach. Comprehensive gene and protein interaction networks were reconstructed for candidate genes involved in the most related immune pathways associated with resistance to ovine GINs using data mining from literature. Generally, 30 genes including CD53, CHIA, RELN, HRH1, EPS15, LRP8, ATP2B1, IL4, IL5, IL13, IL2RA, IL23R, TNFα, IFNγ, TBX21, SH3RF1, HERC2, PTPN1, BIN1, HERC5, C3AR1, NOS2, STAT5B, STAT4, CCL1, CCL8, VIL1, CXCR1, CXCR2, and CXCR4 located on chromosomes 1, 2, 3, 4, 5, 6, 11, 13, 19, and 20 have been found as containing effective regions with the most related pathways to nematode infections. The results obtained by network analysis showed two functional modules, belonging to the interleukins family (IL4, IL5, IL13, IL23R, and IL2RA) and chemokine receptors or ligands family (CXCR1, CXCR2, CXCR4, CCL1, and CCL8). Interleukins are a group of cytokines that are expressed by white blood cells with a major role in the immune system. Chemokines are also a family of chemoattractant cytokines which play a vital role in cell migration that influence the immune system by a process known as chemotaxis. The results provide useful information for the functional annotation of candidate genes related to parasite resistance and add new information towards a consensus on quantitative trait loci (QTLs) related to the incidence of nematode infections.