Contortus L3 Research Articles

Evaluation De L’activité Anthelminthique Des Extraits Aqueux De Striga Hermonthica (Del.) Benth Et Ceratotheca Sésamoïdes Endl Sur Deux Stades Biologiques De Haemonchus Contortus

Medicinal plants with anthelmintic properties are an alternative to the chemical fight against small ruminant’s gastrointestinal nematodes. In order to broaden the spectrum of medicinal plants with anthelmintic properties, ovicidal activity and L3 larvae exsheathment of C. sesamoïdes Endl and S. hermonthica (Deli) Benth, aqueous extracts has been done on H contortus egg and L3 larvae. Three concentrations, 3.12 mg / ml, 6.25 mg / ml, 12.5 mg / ml of each plant extract were used to assess the inhibition of fresh egg hatching and larval paralysis as well as the 'inhibition of L3 larvae exsheathment. A negative control (PBS1x) and a positive control (levamisole, 2.5 mg / ml) were constituted for the fresh egg hatching inhibition assessment while only the negative control (PBS1x) was constituted to evaluate the inhibition of L3 Larvae exsheathment.1 ml of each concentration was contacted with 1 ml of the egg solution and then incubated for 48 hours at 27 ° C in petri dishes (60X15 Cm) for hatching test inhibition.1 ml of each extract concentration was contacted with 1 ml of the embryonated egg solution after 24 hours of incubation at 27 ° C for the larval paralysis test.

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.

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 < 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 < 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 anthelmintic activity of Dennettia tripetala G. Baker (Annonaceae) Fruits against Haemonchus contortus.

Helminthosis is one of the greatest causes of parasitic disease and loss in animal productivity. As such, the control of helminth parasites is of critical importance. This study was aimed to investigate the in vitro anthelmintic activity of Dennettia tripetala G. Baker (Annonaceae) fruits against Haemonchus contortus. Using in vitro techniques, the anthelmintic activity of extracts and fractions of D. tripetala G. Baker (Annonaceae) was evaluated for ovicidal (Egg hatch inhibition test) and larvicidal (larval mortality test) activity. Besides, the maximum tolerated dose was determined in adult albino rats administered, 300, 400, and 500mg/kg body weight of the CME fraction, and observed over a period of 48h for signs of toxicity and mortality. Phytochemical screening uncovered the occurrence of flavonoids, steroids/triterpenes, cardiac glycosides, saponins, tannins, carbohydrates, and alkaloids in the crude methanol extract (CME), the ethyl acetate fraction (EAF), and butanol fraction. The maximum tolerated dose of the CME of D. tripetala did not produce observable signs of toxicity or death in all the rats given up to 500mg/kg. The CME and EAF of D. tripetala fruits produced a significant ( ) reduction in the hatchability of H. contortus eggs in a concentration-dependent manner, while the CME at concentrations between 12.5 and 100mg/ml completely inhibited the hatching of H. contortus eggs. Similarly, EAF at doses of 25, 50, and 100mg/ml completely inhibited the hatching of H. contortus eggs. The CME and EAF of D. tripetala fruits produced significant ( ) larvicidal activity against L3 of H. contortus in a concentration-dependent manner while the CME at concentrations between 6.25 and 100mg/ml caused larval mortality of H. contortus L3 larvae completely. This study suggests that methanol extract and fractions of D. tripetala fruits possess beneficial anthelmintic (ovicidal and larvicidal) activity against H. contortus, and may be a suitable alternative anthelmintic candidate for the control of nematodes.

Impact of Dietary Condensed Tannins and Haemonchus contortus Infection in Growing Sheep: Effects on Nutrient Intake, Digestibility, and the Retention of Energy and Nitrogen.

A controlled study evaluated the effect of condensed tannins (CT) from Gymnopodium floribundum leaf meal (GF), infection with Haemonchus contortus (I) and their interaction, on feed intake, diet digestibility and retention of N (NR) and energy (ER) in hair sheep lambs. Thirty-six, worm-free hair sheep lambs (14.9 ± 1.56kg body weight) were housed in metabolic cages. Eighteen animals were infected with 6000 H. contortus L3, while other 18 lambs were kept non-infected. On day 28th post-infection (PI), infected lambs were assigned to three diet groups: a diet without GF (I-NONGF), a diet with GF (I + GF) and a diet with GF + polyethylene glycol (PEG) (I + GF + PEG). Non-infected (NI) lambs were assigned to similar diet groups: NI-NONGF, NI + GF and NI + GF + PEG. The packed cell volume (% PCV), ante-mortem faecal egg counts and post-mortem worm burdens were also evaluated. Infection did not affect digestibility, NR and ER. Meanwhile, CT intake from the GF diet reduced the digestibility of dry matter, organic matter and crude protein, as well as NR, compared to lambs consuming the NONGF and GF + PEG diets (P < 0.05). Although, the digestible energy was similar between lambs consuming NONGF and GF + PEG diets, the ER was higher for lambs consuming the control NONGF diet. Diets did not affect the PCV, or the ante-mortem and post-mortem parasitological variables. The costs on N and energy metabolism were mainly associated with the CT content of the GF diet, but other features of the diet such as the high lignin content, seemed to affect animals consuming GF meal. Meanwhile, the H. contortus infection had a non-significant impact.

Ovine β-globin gene: A new qPCR for rapid haplotype identification and association with susceptibility to Haemonchus contortus infection

Two β-globin allelic haplotypes (A and B) were identified in domestic sheep, wherein animals which are homozygous for βB allele (BB haplotype) have a deletion of pre-adult βC-globin and consequently are less tolerant to anemia and hypoxia. Since Haemonchus contortus infection, is associated with severe anemia, studies performed from 1960s to 1990s investigated the association between β-globin haplotype and resistance against this parasite. However, the findings were controversial, pointing out from increased resistance in animals harboring the βA allele to inexistence of association. Thus, our study aimed to develop a qPCR for β-globin haplotype identification, and to evaluate the association between β-globin haplotype and resistance against H. contortus in a group of sheep submitted to artificial infection with this parasite. A total of 286 lambs of Morada Nova breed were experimentally challenged with 4000 H. contortus L3 and monitored for 112 days from weaning. Significantly improved (p < 0.05) phenotypic profiles (lower fecal egg counts, higher packed cell volume and birthweight) were observed for AA haplotype animals, especially when compared to BB animals, while AB animals were similar to BB. This is the first report of a qPCR assay for ovine β-globin haplotype identification. In view of significant differences of phenotypic profiles between haplotype groups, the developed qPCR may constitute an important tool for sheep producers to improve genetic selection of parasite resistant animals.

In vitro Evaluation of the Nutraceutical Potential of Theobroma cacao pod Husk and Leaf Extracts for Small Ruminants.

Some agroindustrial by-products could be used as nutraceutical materials for small ruminants helping with their nutrition while controlling their gastrointestinal nematodes. This study evaluated the potential invitro nutraceutical value of pod husks and leaves of three varieties of Theobroma cacao using two Haemonchus contortus isolates with different polyphenol susceptibility. Leaves and husks from three T. cacao varieties (AZT, CAL and CEY) were evaluated for their bromatological composition, invitro dry matter digestibility and polyphenol content. Acetone:water extracts (70:30) of each plant variety were evaluated using the egg hatch and larval exsheathment inhibition tests, using two isolates (FESC and PARAISO) of H. contortus. Effective concentrations 50% (EC50) were determined for both tests. The role of polyphenols was confirmed using polyvinylpolypyrrolidone. L3 exposed to CAL leaf extract were submitted to transmission electron microscopy. Both plant materials showed a good nutritional value to complement protein-rich diets for small ruminants. Extracts inhibited exsheathment of H. contortus L3 more effectively than the egg hatching, and the leaf extracts were more active than husk extracts in the L3 exsheathment inhibition. The FESC isolate was more sensitive to extracts. Polyphenols blocked exsheathment inhibition of leaf extracts. Structural damage was observed in the sheath and muscles of L3 exposed to CAL leaf extracts. The two T. cacao materials tested showed their potential to be used as ruminant feeds. Extracts affected H. contortus by blocking L3 exsheathment, particularly with the leaf extracts. The in vivo nutraceutical value should be confirmed in small ruminants.

Nematicidal activity of a hydroalcoholic extract of the edible mushroom Neolentinus ponderosus on L3 larvae of Haemonchus contortus.

In the present study, the in vitro and in vivo effect of the hydroalcoholic extract of Neolentinus ponderosus (EHNP) on L3 larvae of Haemonchus contortus was evaluated. The N. ponderosus fungus was cultivated in potato dextrose liquid medium for 7days at 120rpm and 25°C. Subsequently, the EHNP was obtained; in vitro bioassays were performed in 96-well plates. Furthermore, an in vitro confrontation with different concentrations of EHNP was carried out at 72h against L3 larvae of H. contortus. The controls used were distilled water and ivermectin at 5mg/mL. Subsequently, the in vivo activity of EHNP was evaluated using the gerbil against H. contortus L3 larvae as an experimental model. The experimental design consisted of four groups with: (1) distilled water, (2) fenbendazole at 20mg/kg of body weight, (3) EHNP at a dose of 81µg/mL, and (4) EHNP at a dose of 40µg/mL. In vitro study showed 97% mortality of the parasite H. contortus at a concentration of 3.4mg/mL and a lethal concentration (LC90) of 2mg/mL EHNP. In the in vivo assessment the highest mortality was (49%) at 72h at a concentration of 81µg/mL bw. The result of the present study shows that EHNP has nematicidal activity in vitro and in vivo tests (close to 97% and 50%, respectively), the fungus N. ponderosus should be considered in future tests to elucidate the secondary metabolites through spectroscopic studies.

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.

Haemonchus contortus hepatocellular carcinoma-associated antigen 59 with poly (lactic-co-glycolic acid): A promising nanovaccine candidate against Haemonchus contortus infection

Hepatocellular carcinoma-associated antigen 59 (HCA59), one of significant excretory/secretory products of Haemonchus contortus (HcESPs), is identified to have immunomodulatory eff ;ects on host cells. However, protection potential of the molecule in H. contortus remains poorly understood. In this study, H. contortus recombinant HCA59 protein amalgamated with poly (lactic-co-glycolic acid) (PLGA) nanoparticle adjuvant was tested for its protection against H. contortus infection in goats. Fifteen goats were allocated into three groups. On days 0 and 14, rHCA59 group was immunized with PLGA nanoparticles encapsulated with recombinant protein HCA59 (rHCA59-PLGA) respectively. Positive control group was unvaccinated, but challenged with H. contortus third stage larvae (L3). Negative control group was unvaccinated and unchallenged with L3. Goats in rHCA59 group and positive control group were challenged with 8000 H. contortus L3 after 14 days of the second immunization. Following immunization, high level of sera IgG, IgA, and IgE, as well as significantly high production of IL-4 and IL-9 was produced in rHCA59 group. After L3 challenge, the level of IL-17 and TGF-β in rHCA59 group increased obviously. Meanwhile, the fecal eggs and the abomasal worm burdens in rHCA59 group was reduced by 44.1 % and 54.6 %, respectively. The studies suggested that rHCA59-PLGA nanoparticles conferred partial protection and could be a good candidate for the development of nanovaccines against H. contortus infection in goats.

Protective efficacy of Barbervax® in Merino weaner sheep trickle infected with five doses of Haemonchus contortus infective larvae

Barbervax® protects sheep against H. contortus infection; however, the level of protection afforded by the vaccine at different levels of larval challenge under field conditions has not been reported. Therefore, this study was designed to investigate the protective efficacy of Barbervax® at increasing doses of trickle infection with H. contortus third stage larvae (L3). Merino lambs (220) were randomly allocated to challenge treatment groups and received Barbervax® vaccinations at approximately 8, 11, 15 and 22 weeks of age or not vaccinated (control group). Animals within each treatment group were subjected to one of five levels of H. contortus L3 trickle infection (0, 300, 600, 1200 and 2400 L3/week in two split doses). Trickle infections started two weeks after the third vaccination (week 0). Worm egg count (WEC), packed cell volume (PCV), antibody titre and bodyweight were measured at week 2 (start of trickle infection), week 5 and then every two weeks for 11 weeks. Vaccinated weaners had a significantly (P < 0.0001) lower faecal WEC than unvaccinated control animals. Vaccination induced significant specific antibody responses that were not influenced by level of trickle infection. Vaccination significantly reduced the number of weaners requiring salvage anthelmintic treatment (9.4% vaccinated weaners versus 33.6% unvaccinated). Vaccine protective index based on WEC was similar at all challenge levels (overall mean> 60%) and at the higher challenge levels did not reduce H. contortus infection to levels that would not require anthelmintic treatment. Therefore, it is suggested that under conditions of high larval challenge the use of Barbervax® should be integrated with other control methods.

In Vivo Anthelmintic Activity of Whole Plant Powder of Striga Hermonthica (Deli.) Benth

The fight against Gastro-Intestinal Nematodes is an urgent necessity for the sheep’s productivity improvement in Burkina Faso. The anthelmintic activity of S. hermonthica’s whole plant powder was evaluated on Mossi sheep artificially infested with H. contortus L3 larvae. The experiment lasted 21 days with 2 phases of 4 days of treatment separated by 6 days in station. Two (2) treated lots of 6 sheep each received respectively 17g/kg of body weight and 10g/kg of body weight while two (2) control lots of 6 sheep each, one negative without treatment and one positive treated with levamisole 1/2 bolus for 25 kg were constituted. The faecal egg count (FEC) reduction rate was high during treatment and reached 84.49% for the 17g/kg body weight dose and 83.69% for the 10g/kg body weight dose at D21. Statistical analysis shows no significant difference between the two doses tested and between the two doses and the positive control, whereas the difference is significant (P&lt;0.05) with the negative control. The mean hematocrit level ranged from 24 at D0 to 30.5 at D21 for the 17g/kg body weight treatment and from 25.83 at D0 to 31 at D21 for the 10g/kg body weight dose. The average daily gain (ADG) of the treated lots was not significant compared to the negative control (P&gt;0.05).

Artemisia cina 30 CH homeopathic treatment against Haemonchus contortus

The anthelmintic resistance problem is widely recognized in sheep production. Therefore, new methods of control against gastrointestinal nematodes (GIN) need to be integrated. The aim of this work was to assess the toxicity of A. cina 30 CH as a homeopathic product against Haemonchus contortus in in vitro and in vivo assays. A. cina 30 CH was obtained from a commercial laboratory, and confirmation of artemisinin as a key ingredient was performed with mass spectrophotometry. The A. cina 30 CH and the artemisinin pure reagent were used for the inhibition of egg hatching (IEH) and for the inhibition of larval migration of H. contortus L3 (ILM). In addition, three groups of 10 naturally infected lambs with GIN were treated with A. cina 30 CH and albendazole, and 10 were used as control. The parasitic infection was monitored at 0, 7, 14 and 28 d postreatment (PT) to determine the number of eggs per gram (epg) and FAMACHA index. The in vitro data showed 100 % IEH and 64.7 % ILM by A. cina 30 CH, and nonlethal activity was observed with the artemisinin pure reagent. The toxicity of A. cina 30 CH against H. contortus in infected lambs was observed after 7 d of infection. Administration of the A. cina 30 CH yielded a 69 % reduction in the epg at 28 d PT, similar to the albendazole (P&lt;0.05). In conclusion, A. cina 30 CH had the ability to IEH and ILM of H. contortus in in vitro assays and reduced the number of eggs of H. contortus, which is the primary parasitic nematode in grazing lambs, thereby reducing infection.

Comparative study of transcription profiles of the P-glycoprotein transporters of two Haemonchus contortus isolates: Susceptible and resistant to ivermectin

The objective of this study was to analyze the mRNA transcription levels of ten functional genes of P-glycoproteins (P-gp) in free life stages, eggs and infective larvae (L3) and in endoparasitic stages, fourth larval stage (L4) and adult males of two native isolates of Haemonchus contortus: resistant and susceptible to IVM. The IVM resistant isolate was obtained from sheep naturally infected with H. contortus, and the susceptible isolate (with no pressure to IVM) conserved since 1990. The lethal effect of IVM was evaluated under in vitro conditions, which showed significant differences between susceptible and resistant H. contortus L3 isolates (P < 0.01). The IVM susceptible isolate revealed a lethal effect of 79.22% at 11.42 mM, whereas that resistant isolate showed no lethal effect at any of the four assessed concentrations (1.43, 2.85, 5.71 and 11.42 mM) of IVM. The expression levels of ten Hco-pgp genes (1, 2, 3, 4, 9, 10, 11, 12, 14, and 16) were evaluated in the resistant isolate of H. contortus and compared to the susceptible isolate (as control), using two constitutive genes (GAPDH and β-tubulin). Up-regulation at two statistical significant values (P ≤ 0.05, 0.1) was the criterion to associate IVM resistance with the free life and endoparasitic stages of H. contortus. The expression levels in H. contortus adult nematodes showed 5.64 to 127.56-fold increase for Hco-pgp genes 1, 9, 12, 14, and 16, followed by an increase for Hco-pgp-2 (49.75-fold) and Hco-pgp-10 (106.40-fold) in L4, and for Hco-pgp-16 (2.90-fold) in eggs (P ≤ 0.05). In addition, high expression levels with P < 0.1 were detected in H. contortus L3, L4, and adults for Hco-pgp genes 1, 4, 11, 12, and 16, with changes ranging from 2.17 to 29.72-fold. In conclusion, the highest expression was observed in the adult stage of H. contortus, and the most frequent gene with a significant P-value was Hco-pgp-16, revealing it plays an important role in IVM resistance.

Is there competition between Haemonchus contortus and Haemonchus placei in a pasture grazed by only sheep?

This study aimed to evaluate the dynamics of Haemonchus contortus and Haemonchus placei infections and hybridization between these species in grazing sheep without contact with cattle. On January 14, 2014, sixteen young sheep were infected with 4000 infective H. placei third-stage larvae L3; 11 days later, another group n = 16 was infected with 4000 H. contortus L3. The establishment rates of H. contortus and H. placei L3 were, on average, 61.6 % and 56.8 %, respectively, in the permanent sheep. After the establishment of patent infections, all permanent sheep were allocated together in the same clean pasture where they grazed for the next 12 months. Euthanasia of a sample of the permanent sheep was performed every three months: in May, August, November and February. Two weeks before the sheep were removed for euthanasia, 2 worm-free tracer sheep were introduced to the pasture to evaluate the larval population in the field. The tracer sheep grazed alongside the permanent sheep for 2 weeks. Then, they were housed indoors for 20 days; at the end of this period, they were euthanized. Parasites were recovered from the permanent and tracer sheep and identified using morphological and molecular techniques. A total of 432 worms (from permanent and tracer animals) were analyzed by PCR using species-specific primer pairs. Of these specimens, only two (0.46 %) male worms were identified as hybrids: one was recovered from a permanent animal euthanized in August and the other from a tracer sheep that grazed in May. The last detection of adult H. placei worms occurred in sheep euthanized in May (approximately 3.5 months after the beginning of the grazing period). The morphological evaluation of the L3 produced in fecal cultures showed that H. placei were progressively replaced by H. contortus populations starting in March. The last trace of H. placei L3 was found in August, when a small percentage (0.5 %) of infective larvae with H. placei morphology was identified in a fecal culture. In conclusion, hybridization between H. contortus and H. placei can occur in the field during coinfection. It was demonstrated that H. placei established successfully in artificially infected worm-free sheep; however, with concomitant natural reinfection with H. contortus, the H. placei population showed a rapid decrease and was eliminated within a few months in an environment without cattle.

In vitro nematicidal activity of two ferrocenyl chalcones against larvae of Haemonchus contortus (L3) and Nacobbus aberrans (J2).

The main goal of this work was to evaluate the in vitro biological activity of two ferrocenyl chalcones (FcC-1 and FcC-2) against Haemonchus contortus (third-stage larvae (L3)) and Nacobbus aberrans (second-stage juveniles (J2)). Both compounds were synthesized and characterized by usual spectroscopic methods and their molecular structures were confirmed by single-crystal X-ray diffractometry. Nematode strains were examined in terms of percentage mortality of H. contortus (L3) by the action of FcC-1, which showed an effectivity of 100% at a concentration of 342 μM in 24 h, with EC50 = 20.33 μM and EC90 = 162.76 μM, whereas FcC-2 had an effectivity of 72% at a concentration of 342 μM in 24 h, with EC50 = 167.39 μM and EC90 = 316.21 μM. The effect of FcC-1 against nematode phytoparasite N. aberrans showed a better percentage of 95% at a concentration of 342 μM, with EC50 = 7.18 μM and EC90 = 79.25 μM, whereas the effect of FcC-2 was 87% at 342 μM, with EC50 = 168 μM and EC90 = 319.56 μM at 36 h. After treatment, the scanning electron micrographs revealed deformities in the dorsal flank and posterior part close to the tail of H. contortus L3. They showed moderate in vitro nematicidal activity against H. contortus L3 and N. aberrans J2.

197 Utilization of Katahdin rams with lower fecal egg count estimated breeding values improves parasite resistance and fitness traits of progeny

Abstract Genetic selection for internal parasite resistance in sheep is a valuable tool to mitigate effects of parasitism especially when significant within breed variability exists. To better understand the mechanism underpinning this variability, a divergent mating scheme was established. Katahdin rams (n = 4) were selected based on their estimated breeding value (EBV) for fecal egg count (FEC) and grouped as numerically high (HiFEC; n = 2) or low (LoFEC; n = 2). Rams were randomly mated to Katahdin ewes at the Southwest Virginia Agriculture Research and Extension Center. Lambs were born mid-March and managed as one group, then weaned in mid-June. Lambs were transported to the WVU Animal Sciences Farm where they were randomly allocated to four pens with even distribution of sire and sex. All lambs (n = 109) were infected with 10,000 H. contortus L3 and the infection persisted for 5 weeks. Weights, FEC, and packed cell volume (PCV) were collected weekly. Statistical analysis was performed using the Mixed Model procedure and repeated measures in SAS with fixed effects of sire group. Weaning FEC was numerically greater for HiFEC-sired lambs vs. LoFEC-sired lambs (2914 vs. 1821 eggs/g; respectively). However, death loss for HiFEC-sired lambs tended to be almost twice that of LoFEC-sired lambs (20% vs. 11%, P = 0.09; respectively). Weaning weights did not differ. Fecal egg count from the prepatent to patent period was greater in HiFEC vs. LoFEC-sired lambs (210 vs. 34 eggs/g; P = 0.05). Packed cell volume was numerically lower in HiFEC-sired lambs. There were no differences in post-weaning growth, ultrasound fat thickness, or loin depth in lambs from divergent sire groups. These data indicate that utilizing LoFEC EBV sires reduces FEC and improves disease resistance in progeny without affecting growth or carcass traits

Viability of Haemonchus placei parasitism in experimentally infected young goats

The present study aimed to evaluate the viability of Haemonchus placei parasitism in experimentally infected goats. For that, 14 75 days old kids male Saanen kids were placed in one of the four experimental groups: GI – infected with 5000 H. placei L3 (n = 4); GII – infected with 5000 H. contortus L3 (n = 4); GIII – infected with 2500 H. contortus L3 + 2500 H. placei L3 (n = 4), and GIV – control, inoculated with distilled water (n = 2). Each kid received, orally, the infective dose in a single inoculum. Based on daily fecal egg counts, the average pre-patent period was determined as 24 days for H. contortus, and 31 days for H. placei. Regarding the Haemonchus spp. recovered at necropsy, the experimental groups GI, GII, and GIII had, respectively, an average of 25.5, 619.5, and 724.75 (120 H. placei, and 604.75 H. contortus) adult specimens, and no immature forms. Under the conditions of this study, the viability of goat infection by H. placei was confirmed, although, with low susceptibility. Nevertheless, the parasitism of this helminth species was more intense when associated with H. contortus. This fact indicates that in common grazing between cattle and young goats, when the latter end up ingesting both Haemonhcus species, especially in a mixed infection, H. placei may also parasitize them.

Behavioural and productive response to experimental infection with stage 3 larvae of Haemonchus contortus in feedlot bull-calves

Haemonchus contortus is a nematode parasite that establishes in the abomasum of ruminants, it has a cosmopolitan distribution and is a worldwide health problem for livestock. As a first line of defence against parasites, behaviour can help to prevent or fight infection, and may even serve as a method of early presumptive diagnosis. Parasites can affect performance of cattle and cause significant economic losses. The aim of this study was to determine the behavioural and productive changes induced by an experimental infection with H. contortus L3 in bovines. We used 32 dewormed bull calves, randomly divided into two groups, 8 no inoculated controls and 24 that were inoculated with 4000 L3 of H. contortus. Inoculation did not influence haematocrit or haemoglobin values at 0, 28 and 42 days post infection (P> 0.20); however, an increase in the frequency of urination (P = 0.0001) and defecation (P = 0.0001), number of steps (P < 0.001) and self-grooming (P < 0.01) events were observed, even in inoculated animals in which not parasite eggs were found in faeces. During the first 28 days post-inoculation with H. contortus, feedlot performance was not affected (P = 0.16), but during the last 14 days (29–42) inoculated animals gained 15% less weight compared to controls (P = 0.04). Over 42 days, inoculated calves showed a 28% poorer feed efficiency during the 42 days post-inoculation than controls (P < 0.01). Across the experiment, calves inoculated with H. contortus obtained less net energy both for maintenance as for gain from diet (P < 0.01). It is concluded that both, performance and behaviour were modified in feedlot bull-calves parasitized by H. contortus, supporting the practice of deworming when eggs of this parasite are detected in the faeces even in low amounts.

Morada Nova sheep breed: Resistant or resilient to Haemonchus contortus infection?

Morada Nova is a Brazilian hair sheep breed that is well adapted to the country’s mainly tropical climate and has good potential for meat and leather production. This breed is reported to be resistant to Haemonchus contortus infection, a highly desired characteristic due to the large impact of this parasite on sheep farming. Therefore, the present study aimed to characterize 287 recently weaned Morada Nova lambs and 123 ewes in relation to their resistance against H. contortus. The animals were dewormed and 15 days later artificially infected with 4000 H. contortus L3 (D0). They were individually monitored by periodic assessment of fecal egg count (FEC), packed cell volume (PCV), and live weight (LW). On D42, the sheep were again dewormed and submitted to a new parasitic challenge, following the same scheme. The animals of each category (lambs and ewes) were ranked according to individual mean FEC values, and classified as resistant (R, 20%), intermediate (I, 60%), or susceptible (S, 20%) to H. contortus infection. At weaning, high FEC were observed in all three phenotypes (P>0.05). After the artificial infections, there was a significant difference (P<0.05) among the three lamb phenotypes for the mean FEC (R<I < S), PCV (R>I > S), and LW (R=I > S). The infection levels (FEC) were negatively correlated with PCV (r = -0.66; P<0.001), and LW (r = -0.30; P<0.001). Despite this, the lambs were resilient, since more than 88% of these animals maintained the PCV above 24%, even when heavily infected. The importance of selective parasite control before weaning to reduce the negative impact on slaughter weight was evidenced, taking into account the high positive correlation between LW at weaning and final LW (r=0.73; P<0.001). The ewes, in turn, were strongly resistant to the parasite. Despite highly significant differences (P<0.001) for mean FEC between phenotypes (R<I < S), 98% of the ewes maintained FEC below 4000 EPG. Their health was not affected, since PCV and LW did not differ between phenotypes, and these parameters were not significantly correlated with FEC (P>0.05). With the phenotypic characterization performed here, it is possible to introduce procedures for parasite control in Morada Nova flocks, facilitating the target-selective treatment approach. The results of this study can also support improvement of meat production by the Morada Nova breed.