L3 Haemonchus Contortus Research Articles

Bio-guided isolation of a new sesquiterpene from Artemisia cina with anthelmintic activity against Haemonchus contortus L3 infective larvae.

Haemonchus contortus is a blood-feeding gastrointestinal parasite that impacts grazing sheep, causing economic losses in animal production. Due to its anthelmintic resistance, alternative antiparasitic treatments like plant-based anthelmintics are necessary to explore. Artemisia cina (Asteraceae) is a plant whose n-hexane extract and ethyl acetate extract exhibit anthelmintic activity against H. contortus, the n-hexane more active. To discover additional bioactive metabolites, a chemical analysis was performed on ethyl acetate extract, which presented an LC90 of 3.30 mg/mL and allowed the isolation of 11-[(1R,5S,7R,8R,10S,)-1,8-dihydroxy-5,10-dimethyl-4-oxodecahydroazulen-7-yl] acrylic acid. This new sesquiterpene was identified through one and two-dimensional NMR. The compound was named cinic acid and displayed an LC50 of 0.13 (0.11-0.14) mg/mL and LC90 of 0.40 (0.37-0.44) mg/mL, which, compared with ethyl acetate extract larvicidal activity, was 256-fold more active at LC50 and 15.71-fold at LC90. In this study, a new sesquiterpene with larvicidal activity against H. contortus L3 infective larvae was isolated from the ethyl acetate extract of Artemisia cina.

Assessing the In Vitro Individual and Combined Effect of Arthrobotrys oligospora and A. musiformis (Orbiliales) Liquid Culture Filtrates against Infective Larvae of the Sheep Blood-Feeding Nematode Haemonchus contortus (Trichostrongylidae).

Arthrobotrys species are nematophagous fungi that secrete extracellular nematocidal products (ECP). The individual and combined effects of ECP from Arthrobotrys oligospora (Ao) and A. musiformis (Am) growth in liquid media against Haemonchus contortus L3 (HcL3) were assessed. The isolation, morphological (MI) and molecular identification (Mol-I), assessment of nematocidal activity (NA) of fungal liquid culture filtrates (LCF) in two liquid media alone and in combination and the myco-compound profile identification (MCP) were performed. The MI suggested that the fungi corresponded to the species Ao and Am. This result was confirmed by PCR analysis followed by sequencing, alignment and a phylogenetic analysis. Likewise, the highest Hc mortalities were 91.4% with individual LCF of Am and 86.2% with those of Ao at the highest concentration (100 mg/mL) in Czapek-Dox Broth. The combination of both LCF resulted in a similarly high larval mortality with no statistical differences in relation to individual activity (p > 0.05). The MCP showed the presence of alkaloids in both fungi. Coumarins, sterols and saponins were found only in Ao. Both fungi produced ECP with a high NA that could be identified and assessed in future studies as potential natural anthelmintic compounds.

Exploring AMH levels, homeostasis parameters, and ovarian primordial follicle activation in pubertal infected sheep on a high-protein diet

“Exploring AMH Levels, Homeostasis and Primordial Follicle Activation in Pubertal Infected Sheep on a High Protein Diet “.The first activation wave of ovarian primordial follicles is part of the onset of puberty and fertility. Abomasal helminth infection may cause an undesirable delay in puberty manifestation. Helminth-infected animals demand a higher amount of protein in their diet to repair the damage caused by the parasite in sheep's tissues, replenish the blood losses, and build the host's immune response. Helminths become resistant to drug therapy shortly after being exposed to a new treatment. Besides, there is the possibility of contamination by anthelmintic drugs in ovine products, possibly affecting human health and the environment. This study's objective was to evaluate if ovarian and clinical parameters can be improved by supplementing their diet with protein, offering a more sustainable management approach than relying on anthelmintic usage. We used a 2 × 2 factorial model where eighteen ewe lambs (Ovis aries) between 6 and 7 months old - born to the same ram - were fed one of two diet protein levels (12% or 19%). After 35 days on this diet, they were infected or left uninfected with 10,000 Haemonchus contortus L3 larvae. We evaluated Anti-Mullerian Hormone serum levels, blood cells and biochemical parameters at four different time points. Following 42 days of infection and 77 days on the diet, the lambs had their left ovaries removed, and we examined ovarian morphometrics through histological analysis. The groups Supplemented Protein-Infected(n = 5), Control Protein- Infected(n = 5), Supplemented Protein-Not Infected (n = 4) and Control Protein-Not Infected (n = 4) did not differ in their bodyweight gain. In the factorial ANOVA analysis examining the relationship between plasma protein, diet, and infection, the protein level of the diet showed significance (p = 0.02). Primordial follicle size varied with the interaction between diet and infection (p < 0.05), and oocyte size was affected by the level of protein in the diet (p = 0.047). Additionally, to understand how all homeostasis parameters relate to the primordial follicle and oocyte size, we applied an explanatory linear mixed model. In conclusion, serum AMH levels remained stable despite the infection and variations in diet protein levels, indicating its reliability as a marker for ovarian reserve in pubertal sheep. The number of blood cells, biochemical parameters, and primordial follicle activation were affected by both diet and infection.

First Record of Flavocillium subprimulinum (Cordycipitaceae, Hypocreales) in Mexico: Morphological and Molecular Characterisation, Nematocidal Activity of Its Liquid Culture Filtrates against Haemonchus contortus and Protease Activity.

This is the first record of the fungus Flavocillium subprimulinum in Mexico. The isolate was taxonomically characterised and cultured in potato dextrose broth (PDB), Czapek-Dox broth (CzDoxB), and sweet potato dextrose broth (SPDB) to obtain its filtrates (FLCF). The nematocidal activity (NA) of three FLCF concentrations was assessed against Haemonchus contortus L3. Protease activity (PA) was assessed with SDS-PAGE, followed by a zymogram. The NA of the FLCF reached 94.43% in PDB and 95.82% in CzDoxB, respectively, at 100 mg/mL. Lower mortality (64%) was found in SPDB at 100 mg/mL. SDS-PAGE showed bands (in PBS) of ~25, ~40, and ~55 kDa. The zymogram showed protein bands (PBs) with PA in the media, including PBs of ~14, ~40, and ~55 kDa. This study establishes the basis for exploring the potential use of this fungus against H. contortus, which is considered the most pathogenic parasite affecting lambs.

Cassia sieberiana root bark used in traditional medicine in Togo: Anthelmintic property against Haemonchus contortus and tannins composition

• UPLC-MS/MS tannins profiling of ethyl acetate extract of C. sieberiana root bark. • 23 flavan-3-ol metabolites newly described in C. sieberiana . • 3 flavan-3-ols reported for the first time in the literature. • Anthelmintic properties of C. sieberiana extracts in Larval Migration Inhibition test. • Validation of C. sieberiana as anthelmintic drug to slow down the infection dynamic. Helminth infections of livestock result in economic losses around the globe. The majority of the people in West Africa treats such infections with medicinal plants related to the local traditional medicine. In a previous ethnomedicinal survey carried out in the north of Togo, traditional healers frequently cited Cassia sieberiana DC to treat helminth infections. The aim of the present study was to validate the traditional application of C. sieberiana root bark as a dewormer and to analyse the metabolite composition in preparations with this activity. Two tannin-rich fractions (FrE14 and FrE15) obtained from ethyl acetate extract were submitted to UPLC-MS analysis. The anthelmintic activity of C. sieberiana extracts and tannins-rich fractions was investigated on the small ruminant parasite Haemonchus contortus using Larval Migration Inhibition tests. The ethyl acetate, butanol and aqueous extracts significantly disrupted larval migration of Haemonchus contortus L3 with inhibition of 30.3%, 22.2% and 26.5% respectively at 2.5 mg/mL, as compared to negative control. The two tannin-rich fractions, FrE14 and FrE15 presented larval migration inhibition of 6.5% and 20.7% respectively at the same concentration. From these two fractions, 28 flavan-3-ols were identified including 3 monomers (catechin, epicatechin and epiafzelechin), 22 dimers (7 homodimers and 15 heterodimers) as well as 3 newly described trimers consisting of (epi)afzelechin, (ent)cassiaflavan or (epi)guibourtidinol subunits.

PSV-B-21 Genome-Wide Analysis of Sheep Artificially or Naturally Infected with Gastrointestinal Nematodes

Abstract Gastrointestinal nematodes (GIN) are detrimental to the health and productivity of sheep across the world, necessitating genetic selection for improved GIN resistance. In this study, we used genomic analyses across- and within- two important breeds in the United States (US), Rambouillet and Dorper, to investigate physiological mechanisms associated with GIN resistance. Genomic data were evaluated from two experiments where lambs were challenged with GIN, either in a natural environment or artificially. Lambs were genotyped with the Axiom™ Ovine Genotyping Array (50K) with 42,608 single nucleotide polymorphisms (SNP) remaining following quality control for minor allele frequency and variant call rate. In experiment 1, a fecal egg count (FEC) was collected from four- to eight-month-old Dorper and Rambouillet lambs (n=188 total) exposed to GIN on pasture. Using Plink v1.9, a genome-wide association study (GWAS) identified significant SNP (P &amp;lt; 6.0e-5) associated with either an increase or decrease of FEC on chromosomes 1, 2, 3, 4, 12, 15 and 20. In Experiment 2, Rambouillet lambs (n=77) were inoculated with 10,000 Haemonchus contortus L3 larvae and FEC and packed-cell volume (PCV) were recorded. An ensuing GWAS identified significant SNP (P &amp;lt; 2.0e-5) on chromosomes 1, 2, 3, 5, 7, 16, 17 and 23 associated with high and low FEC and SNP on chromosome 10 associated with decreased PCV. Multiple genes were in proximity to the identified SNP, including PIK3 subunits in both experiments. Pathway analysis of reported genes, including PIK3, IMP4, NDST3, MRPL22, HSPA2, TGFA, TGFBR1 and RUNX1 revealed involvement in tissue repair, T-cell differentiation and cytokine signaling in Rambouillet and Dorper sheep more resistant to GIN. Results from this study contribute to the genetic underpinnings of host response to GIN in two important breeds in the US, providing a foundation for future selection of animals more resistant to H. contortus infection.

Evaluation of terminal sire breeds for hair sheep production systems: Feedlot environment

Improving carcass merit while maintaining parasite resistance in Katahdin crossbred lambs has potential to improve profitability for U.S. sheep producers. To assess crossbred lamb parasite resistance, carcass merit and gain, purebred Katahdin ewes from the Southwest Virginia Agricultural Research and Extension Center (Glade Spring, VA) were mated to Katahdin (KT), Suffolk (SU) or Texel (TX) rams for three years. Lambs were born and raised in Virginia. Two weeks post-weaning, lambs were transported to the West Virginia University Animal Science Farm (Morgantown, WV). Lambs were dewormed and transitioned to a complete pellet (16% CP) and fed ad lib for the duration of the study. After transition, all lambs were infected with 10,000 Haemonchus contortus L3 larvae (HcL3) in suspension given orally. Weights, blood and fecal samples were collected weekly. After a 5 week primary infection, all lambs were treated with levamisole (8 mg/kg) and rested for 2–3 weeks, after which, lambs were challenge infected with 10,000 HcL3 and sampled weekly until slaughter endpoint in Years 1&2. Ultrasonic determination of REA and fat depth occurred 1 week prior to slaughter in Years 1&2. In Year 3 carcass evaluation did not occur and ultrasonic measurements were taken at termination of the trial. In Years 1&2, 5 lambs from each sire group (n = 15) were randomly selected for carcass analysis at the Virginia Tech Meats Laboratory. No significant sire effect differences were observed in FEC during primary infections across all 3 years. Fecal egg count of KT lambs peaked at week 6 during challenge infection but reduced FEC rapidly one week later. SU-sired lambs grew faster to a larger body weight than TX sired lambs (55.72 kg vs. 49.51 kg; 0.37 kg/d vs. 0.32 kg/d, P < 0.0001), with KT progeny having the least amount of weight gain (44.8 kg; 0.30 kg/d). Analysis of REA using ultrasound and live carcass measurements exhibited no difference between SU- (16.92 cm2) or TX-sired lambs (17.10 cm2) but both breeds were significantly higher than Katahdin lambs (13.67 cm2;P < 0.01). Leg score favored SU- (11.8) and TX-sired (12.0) lambs compared to KT-sired lambs (10.7;P < 0.01). Feed efficiency measured in RFI showed no significant difference between KT-, SU- or TX sired lambs (−0.08, 0.04, −0.04 kg/d respectively; P = 0.65). Taken together these data demonstrate that carcass merit of TX-sired lambs is equivalent to SU-sired lambs supporting the option of using an alternative terminal sire on Katahdin ewes without detrimental loss of parasite resistance in crossbred progeny.

Ovarian activation delays in peripubertal ewe lambs infected with Haemonchus contortus can be avoided by supplementing protein in their diets

BackgroundThe ewe lamb nutritional and physiological state interfere with the ovarian environment and fertility. The lack or excess of circulating nutrients reaching the ovary can change its gene expression. A protein deficiency in the blood caused by an Haemonchus contortus abomasal infection is detrimental to the organism’s development during puberty. The peripubertal period is a time of intensive growth that requires a high level of nutrients. An essential feature controlling pubertal arousal and female reproductive potential is ovarian follicle growth activation. Protein supplementation improves the sheep’s immune response to helminthic infections. We aimed to determine if supplementing protein in infected ewe lambs’ diet would impact the ovarian environment leading to earlier ovarian follicle activation than in infected not supplemented animals.MethodsWe fed 18 Santa Ines ewe lambs (Ovis aries) - bred by the same ram - with either 12% protein (Control groups) or 19% protein (Supplemented groups) in their diets. After 35 days of the diet, they were each artificially infected or not with 10,000 Haemonchus contortus L3 larvae. Following 77 days of the diet and 42 days of infection, we surgically collected their left ovaries and examined their genes expression through RNA sequencing.ResultsWe found that protein supplementation in infected animals led to an up-regulation of genes (FDR p-values < 0.05) and biological processes (p-value cut-off = 0.01) linked to meiotic activation in pre-ovulatory follicles and primordial follicle activation, among others. The supplemented not infected animals also up-regulated genes and processes linked to meiosis and others, such as circadian behaviour. The not supplemented animals had these same processes down-regulated while up-regulated processes related to tissue morphogenesis, inflammation and immune response.ConclusionDiet’s protein supplementation of peripubertal infected animals allowed them to express genes related to a more mature ovarian follicle stage than their half-sisters that were not supplemented. These results could be modelling potential effects of the interaction between environmental factors, nutrition and infection on reproductive health. When ovarian activation is achieved in a timely fashion, the ewe may generate more lambs during its reproductive life, increasing sheep breeders’ productivity.

61 Oral Dosing Loline Alkaloid and Its Effects Against Mixed Infection of L4 Teladorsagia Circumcincta, and Trichostrongylus Colubriformis, and Adult Haemonchus Contortus

Abstract Loline, an alkaloid produced by Epichloë endophytes in pastoral grass species, is considered non-toxic with suggested antimicrobial and anthelmintic properties. In vivo metabolism of loline suggests ability to reach the abomasum or intestine, and anthelmintic benefit is indicated in vitro when parasites are in either a developmental stage close to the gastric mucus layers or adult stage consuming blood. Therefore, the objective of this project was to investigate the validation of using a loline seed extract as a natural anthelmintic in parasitized lambs. Sixteen Coopworth lambs were individually penned, offered ad-libitum lucerne pellets and water and randomly assigned to 3 treatment groups; CON; no treatment, or treatment with a Festuca pratensis seed extract with (LOL) or without loline (NIL). Lambs were orally infected with 20,0000 L3 Haemonchus contortus on day 0, and 10,000 L3 Teladorsagia circumcincta, and Trichostrongylus colubriformis on day 14. Parasites then matured to determine lolines efficacy on blood feeding adult Haemonchus contortus and L4 mucosal browsers Teladorsagia circumcincta, and Trichostrongylus colubriformis. Loline was orally dosed at 52.5 mg/kg LW starting on day 13, and every other day until slaughter for worm enumeration on day 28. Feed intake and refusals were recorded daily, and fecal samples were taken prior to infection, on loline dose days and at slaughter. Worm and fecal egg counts were transformed to log10 and all data were analyzed in Genstat (18th edition). Significance was declared at P &amp;lt; 0.05. Worm burdens of T. circumcincta (P = 0.96), T. colubriformis (P = 0.43), and H. contortus (P = 0.15) were not different between treatments. No treatment difference (P = 0.39) was observed in fecal egg counts, weight gain (P = 0.51), or feed intake (P = 0.18). Average growth efficiency (kg LWG/ kg DM intake) was 0.18 in CON which was less (P = 0.01) than LOL (0.24) or NIL (0.23). In conclusion, limited evidence supported an in vivo anti-parasitic effect of loline.

PSV-7 Sire fecal egg count EBV are predictive of offspring response to an artificial gastrointestinal nematode infection in Rambouillet sheep

Abstract Gastrointestinal nematodes (GIN) pose a significant risk to the health and productivity of Rambouillet sheep, a noted wool and meat producing breed, in the United States. Capturing phenotypic measurements of Rambouillet while infected with GIN is essential for the calculation of estimated breeding values (EBV) as a selection tool to improve host resistance to GIN. Weaned (age= ~120 d.) Rambouillet lambs (n = 75) were each inoculated with 10,000 Haemonchus contortus L3 larvae and placed in a feedlot. Lambs were offspring of two representative sires, A (n = 26) and B (n = 49), with post-weaning fecal egg count EBV (PFEC) from LAMBPLAN, of -9.94 and +9.20%, respectively. Lamb fecal egg count (FEC), packed-cell volume (PCV) and body weight (BWT) measurements were captured at 7-day intervals for 6 subsequent weeks. Actual FEC were loge transformed (lnFEC) to meet normality and then backtransformed least squares means (LSM) are reported. lnFEC, PCV and BWT were analyzed using a mixed model with repeated measures including fixed effects of sex, sire and average daily gain (ADG) classification (for lnFEC and PCV), and sex and sire (for BWT). Significant differences (P = 0.0216) in average lnFEC were observed between offspring from sires A [2242 eggs per gram (epg)] and B (2914 epg). Weekly lnFEC differed (P &amp;lt; 0.0001) and a trend identified between sexes (females = 3414 epg vs males = 2712 epg, P = 0.0909). Interestingly, females exhibited a higher average PCV than males, (34.93% v. 31.15%, P &amp;lt; 0.0001), suggesting potential pathological differences by sex in response to GIN infection. Artificial GIN infections offer a more controlled test than under natural conditions and are a viable option to aid in identifying Rambouillet sheep more resistant to GIN. These results indicate EBV calculated with FEC from a natural GIN infection are predictive of the response of Rambouillet lambs to an artificial infection of H. contortus.

In Vitro Nematocidal Effect and Anthelmintic Activity of Artemisia cina Against Haemonchus contortus in Gerbils and Relative Expression of Hc29 Gene in Transitional Larvae (L3-L4).

(1) To assess the in vitro activity of Artemisia cina against Haemonchus contortus L3 (HcL3) and in transitional (L3-L4) larvae (HcTrL3-L4); (2) to quantify the relative expression of the Hc29 gene in HcTrL3-L4 exposed to the A. cina n-hexane extract; and (3) to assess the anthelmintic activity (AA) of the A. cina organic extracts in gerbils artificially infected with H. contortus (HcArt/inf/gerbs). The in vitro assay was carried out in 96-well microtitration plates. The following A. cina extracts: ethyl acetate (Ac-EtOAcEx), n-hexane (Ac-n-HexEx), and methanol (Ac-MethEx) were assessed at 1 and 2mg/mL against HcL3 and HcTrL3-L4 at 24h exposure. Relative expression of the Hc29 gene in HcTrL3-L4 was obtained by RT-PCR. For assessing the AA, six groups of five HcArt/inf/gerbs were used. Groups were treated orally with 4mg/kg BW of A. cina extracts. Five days after treatment, the gerbils were necropsied and nematodes counted. The highest in vitro activities (75 and 82.6%) were shown by Ac-n-HexEx at 1 and 2mg/mL, respectively. For HcTrL3-L4 the highest in vitro activities (69 and 23%) were shown by Ac-n-HexEx and isoguaiacine at 0.625mg/mL, respectively. Also, upregulation of H. contortus Hc29 gene by 13- and 80-fold (p < 0.01) was observed on the HcTrL3-L4 stage after exposure to Ac-n-HexEx extract and isoguaiacine at 0.078mg/mL, respectively. Reduction percentage was 100% in HcArt/inf/gerbs treated with Ac-n-HexEx. We conclude that the Ac-n-HexEx and isoguaiacine compound had anthelmintic efficacy against H. contortus and L3 and HcTrL3-L4.

PSX-20 Internal parasite resistance measured on pasture and in confinement of young Kiko bucks

Abstract Resistance to internal parasites (IP) is important in the sustainability of a meat goat enterprise. Langston University (LU) and the American Kiko Goat Association conducted a SecondGeneration Buck Performance Test in 2019. The performance test measured fecal egg count (FEC) and packed-cell volume (PCV) in a natural challenge of 6 wk on pasture (PAS) and in an artificial challenge in dry-lot confinement (CON). Seventy-seven Kiko bucks less than 1 yr of age completed both PAS and CON. The PAS was conducted on a 23-ha pasture with native grasses and forbs. Bucks were supplemented at 0.5% BW (25.8±0.18 kg) daily to facilitate visual inspection of animals. CON was conducted at LU’s testing facility. Bucks were sampled every 2 wk in PAS. In CON, bucks were sampled on d 29, 34, and 38 following an artificial challenge with each buck receiving 7,000 L3 Haemonchus contortus larvae. Average FEC and PCV for each buck for PAS and CON were analyzed. The correlation between FEC-PAS and PCV-PAS was -0.283 (P &amp;lt; 0.05), which is almost identical to the correlation between FEC-CON and PCV-CON (r=-0.280, P &amp;lt; 0.05). The Spearman rank correlation between FEC-PAS and FEC-CON was 0.069 (P &amp;gt; 0.50). However, the Spearman rank correlation between PCV-PAS and PCV-CON was 0.376 (P &amp;lt; 0.01). Using mixed model methods, the means for FEC-CON and FEC-PAS were similar (1,428 vs 1,698±169 epg for CON and PAS, respectively). However, PCV were different (P &amp;lt; 0.01), with 28.3 vs. 20.7±0.34 for CON and PAS, respectively. Pasture PCV was a predictor of PCV in confinement and vice versa; however, that was not true for FEC, indicating that FEC in PAS and in CON may be two separate traits. Future buck performance tests should incorporate pasture and confinement phases to more precisely identify superior bucks for IP resistance.

PSIII-42 Diet selection and trade-offs between condensed tannins and nutrients in parasitized sheep

Abstract We determined how parasitized sheep prioritize selection of crude protein, energy and a medicinal plant secondary compound (quebracho tannins-QT). Foraging preferences were tested in 40 lambs before experiencing a parasitic infection (Phase 1), during an infection (Phase 2; 10,000 L3 Haemonchus contortus per lamb) and after chemotherapy (Phase 3). Lambs were assigned to four groups (10 lambs/group) such that animals in Group 1 (Control) could choose between rations of high energy (HE) or high protein (HP) density. The other groups received the same choice, but QT were added (4%) to HE (Group 2), to HP (Group 3) or to both HE and HP (Group 4). Intake and preference indexes were analyzed as a split-plot design with lambs nested within group and day as the repeated measure. All groups increased their preference for HE when parasitized relative to Phase 1 (0.66 and 0.44 ± 0.042, respectively; P &amp;lt; 0.05). As a result, lambs increased their intake of digestible energy during Phase 2 (0.126 ± 0.007 Mcal/kg BW) relative to Phase 1 (0.106 ± 0.007 Mcal/kg BW; P &amp;lt; 0.05). These patterns remained during Phase 3. Only lambs receiving QT in the HE increased their intake of condensed tannins from Phase 1 to Phase 2 (P &amp;lt; 0.05). Fecal egg counts (FEC) and blood parameters revealed a parasitic infection (P &amp;lt; 0.05) in Phase 2 that subsided in Phase 3, although no differences were detected among groups (P &amp;gt; 0.05). The importance of protein nutrition on parasitized animals has been highlighted before, but these results suggest that parasitized lambs prioritized the ingestion of energy-dense over protein-dense foods or medicinal condensed tannins. Nevertheless, intake of tannins increased when these compounds were present in the energy-dense food, suggesting that selection of condensed tannins was influenced by the nutritional composition of the foods during testing.

The Viability of Haemonchus Contortus (Nematoda, Strongylida) and Strongyloides Papillosus (Nematoda, Rhabditida) Larvae Exposed to Various Flavourings and Source Materials Used in Food Production

Abstract The objective of this study is to evaluate the viability of larval nematodes of ungulates under the infl uence of 14 fl avourings and source materials approved for use in and on foods. Minimum LD50 for L3 Strongyloides papillosus (Wedl, 1856) were observed when using Cinnamaldehyde, α-Terpineol and Benzyl alcohol, for L1–2 S. papillosus under the infl uence of Benzyl alcohol, Cinnamaldehyde, L-Linalool and Benzyl acetate, for L3 Haemonchus contortus (Rudolphi, 1803) under the influence γ-Undecalactone and Cinnamaldehyde. Ethyl acetate, β-Ionone и D-Limonene had the lowest effect on all the studied stages of development of the nematodes: larvae did not die during 24 hours even at 1 % concentration of these substances. Further experiments with usage of mixtures of the substances studied in this article will contribute to the development of preparations with a stronger effect on larvae of nematode parasites of the digestive system of vertebrate animals.

Changes in haematological parameters in wild ruminants experimentally infected with Haemonchus contortus

SummaryOur study describes changes in haematological parameters in wild ruminants with parasitic infection. Six European mouflons (Ovis musimon), six fallow deer (Dama dama) and six roe deer (Capreolus capreolus) were experimentally infected with the resistant strain of the model parasite 8000 L3 Haemonchus contortus. The blood samples were collected on Day 0, 16, 37, 58, 77, and 99 of the experiment. Mild anaemia was observed in mouflons and roe deer while red blood cells increased in red blood counts (total erythrocytes, haematocrit and haemoglobin). As for the white blood cells count, leucopenia with neutrophilia and lymphopenia was recorded in mouflons, in the fallow deer and roe deer leucocytosis with neutropenia and lymphocytosis were observed. Changes in the dynamics of haematological parameters were statistically insignificant.

Transcriptome variation in response to gastrointestinal nematode infection in goats.

Gastrointestinal nematodes (GIN) are a major constraint for small ruminant production. Due to the rise of anthelmintic resistance throughout the world, alternative control strategies are needed. The development of GIN resistance breeding programs is a promising strategy. However, a better understanding of the mechanisms underlying genetic resistance might lead to more effective breeding programmes. In this study, we compare transcriptome profiling of abomasal mucosa and lymph node tissues from non-infected, resistant and susceptible infected Creole goats using RNA-sequencing. A total of 24 kids, 12 susceptible and 12 GIN resistant based on the estimated breeding value, were infected twice with 10,000 L3 Haemonchus contortus. Physiological and parasitological parameters were monitored during infection. Seven weeks after the second infection, extreme kids (n = 6 resistant and 6 susceptible), chosen on the basis of the fecal egg counts (FEC), and 3 uninfected control animals were slaughtered. Susceptible kids had significantly higher FEC compared with resistant kids during the second infection with no differences in worm burden, male and female worm count or establishment rate. A higher number of differentially expressed genes (DEG) were identified in infected compared with non-infected animals in both abomasal mucosa (792 DEG) and lymph nodes (1726 DEG). There were fewer DEG in resistant versus susceptible groups (342 and 450 DEG, in abomasal mucosa and lymph nodes respectively). ‘Cell cycle’ and ‘cell death and survival’ were the main identified networks in mucosal tissue when comparing infected versus non-infected kids. Antigen processing and presentation of peptide antigen via major histocompatibility complex class I were in the top biological functions for the DEG identified in lymph nodes. The TGFβ1 gene was one of the top 5 upstream DEG in mucosal tissue. Our results are one of the fist investigating differences in the expression profile induced by GIN infection in goats.

Diet selection and trade-offs between condensed tannins and nutrients in parasitized sheep

Foraging behavior by parasitized herbivores can be interpreted as a decision-making process where individuals are faced with trading-off the ingestion of nutrients with the ingestion of potentially medicinal -and toxic- plant secondary compounds. We determined how parasitized sheep prioritize selection of crude protein, energy and a medicinal plant secondary compound (quebracho tannins-QT). Foraging preferences were tested in 40 lambs before experiencing a parasitic infection (Phase 1), during an infection (Phase 2; 10,000 L3Haemonchus contortus per lamb) and after chemotherapy (Phase 3). Lambs were assigned to four groups (10 lambs/group) such that animals in Group 1 (Control) could choose between foods of high (HEP) or low (LEP) energy to protein ratios. The other groups received the same choice, but QT were added (4%) to HEP (Group 2), to LEP (Group 3) or to both foods (Group 4). All groups under a parasitic infection (Phase 2) increased their preference for HEP (from 0.44 to 0.66 ± 0.042; P < 0.05) and intake of digestible energy (from 0.106 to 0.126 ± 0.007 Mcal/kg BW; P < 0.05) relative to Phase 1, a pattern that remained during Phase 3. Only lambs receiving QT in HEP increased their intake of QT from Phase 1 to Phase 2 (P < 0.05). Fecal egg counts and blood parameters revealed a parasitic infection (P < 0.05) in Phase 2 that subsided in Phase 3, although no differences were detected among groups (P > 0.05). The importance of protein nutrition on parasitized animals has been highlighted before, but these results suggest that lambs prioritized the ingestion of energy-dense over protein-dense foods or medicinal condensed tannins when challenged by gastrointestinal parasitism. Consumption of medicinal tannins represented a side-effect of the preference manifested for energy-dense foods during testing.

Resistance to gastrointestinal nematodes in dairy sheep: Genetic variability and relevance of artificial infection of nucleus rams to select for resistant ewes on farms

Breeding sheep for enhanced resistance to gastrointestinal parasites is a promising strategy to limit the use of anthelmintics due to the now widespread resistance of parasites to these molecules. This paper reports the genetic parameters estimated for parasite resistance and resilience traits in the Blond-faced Manech dairy sheep breed and the putative impacts of the selection for resistance to gastrointestinal nematodes (GIN) on farms. Two datasets were used. First, the rams of the selection scheme were artificially infected twice with L3 Haemonchus contortus larvae. Faecal egg counts (FEC) and packed cell volume (PCV) loss were measured 30 days after each infection. Secondly, the FEC, PCV and body condition score (BCS) (1–6 measures per ewe) of naturally infected ewes on farms were measured in the spring, summer and autumn over a two-year period. Genetic parameters were estimated for each dataset independently but also globally based on the pedigree connections between the two datasets. For the experimentally infected sires, the FEC following the second infection was moderately heritable (heritability: 0.35) and strongly correlated with FEC after the first infection (genetic correlation: 0.92). For the naturally infected ewes, FEC was also heritable (0.18). Using the two datasets together, a genetic correlation of 0.56-0.71 was estimated between the FEC values of the experimentally infected rams and naturally infected ewes. Consequently, the genetic variability of parasite resistance is similar whatever the physiological status (males or milking/pregnant ewes) and the infection conditions (experimental infection with one parasite or natural infection with several parasites). In practice, when the sire population is divided into two groups based on their genetic value, the FEC of the ewes born to the 50% most resistant sires is half that of the ewes born to the 50% most susceptible sires. Our study shows the feasibility and efficiency of genetic selection for parasitism resistance based on the sires’ FEC records to improve parasite resistance in naturally grazing ewes. For breed improvement, and to increase the selection pressure on parasite resistance, it seems more appropriate to measure FEC values on rams after experimental infection rather than on ewes in natural infection conditions because this limits the number and standardizes the conditions of FEC measurements.

The effect of ovine peripheral blood mononuclear cells on Haemonchus contortus larval morbidity in vitro.

The objective of this study was to determine the effects of peripheral blood mononuclear cells (PBMC), derived from parasite-resistant St. Croix (STC) hair sheep and parasite-susceptible Suffolk (SUF) sheep, on Haemonchus contortus L3 stage larval death in vitro, with or without autologous serum. Larval morbidity was quantified by measuring larval ATP concentration following incubation with PBMC. Larvae exposed to either STC- or SUF-derived PBMC had lower ATP than live larvae (0.12μmol/L ATP and 0.16μmol/L ATP vs 0.27μmol/L ATP, respectively) (P<.001) and greater ATP of dead larvae (0.03μmol/L ATP) (P<.001). Breed differences were observed with addition of autologous serum. Larvae exposed to SUF-derived PBMC with autologous serum were not significantly different from live larval ATP. STC-derived serum did not significantly reduce larval ATP compared to PBMC alone (0.11μmol/L ATP), but was significantly reduced compared to live larvae (0.22μmol/L ATP) and SUF-derived PBMC with autologous serum (0.23μmol/L ATP) (P<.001). These data indicate that a cellular response alone is capable of significantly reducing larval ATP in a breed-independent manner. However, addition of serum to SUF-PBMC failed to reduce larval ATP, indicating breed-dependent humoral response to H.contortus.

Molecular identification of abomasal bacteria associated with genetic resistance and susceptibility to Haemonchus contortus infection in sheep

The widespread occurrence of anthelmintic-resistant gastrointestinal nematodes (GINs), particularly Haemonchus contortus, in sheep production systems has magnified the need to identify and develop alternative control strategies. Strategies include the selection of genetically GIN-resistant sheep and the implementation of biological parasite control to reduce dependence on anthelmintic drugs. In this study, we aimed to establish the molecular identity of bacterial communities present in the abomasum of sheep classified as resistant or susceptible to H. contortus, an abomasal parasite. Thirty-eight sheep were experimentally infected with L3 Haemonchus contortus and analyzed for fecal egg count (FEC) and hematocrit (Ht) to establish haemonchosis resistance or susceptibility. Four resistant sheep (RS) and four susceptible sheep (SS) were selected for microbial sampling and subsequent phylogenetic analysis. Molecular identification of the bacteria was based on amplification of the bacterial 16S rRNA gene, construction of a 16S rDNA clone library, and subsequent gene sequencing. Significant differences (p = 0.05) were observed in the occurrence of different phyla identified in RS and SS libraries: Firmicutes (61.4% and 37.2%, respectively), Proteobacteria (10.2% and 37.2%, respectively), Bacteroidetes (12.8% and 5.8%, respectively), and unclassified bacteria (12.8% and 17%, respectively). Differences between the proportions of bacterial communities present in the RS and SS pool samples were observed, contributing as a first step toward the assessment of the association between the gastrointestinal tract microbiota and nematode resistance in sheep.