Revealing the associated microflora hosted by the globally significant parasite Trichostrongylus colubriformis.

Trichostrongylus colubriformis is a parasitic helminth that primarily infects small ruminants, causing substantial economic losses in the livestock industry. Exploring the microbiome of this helminth might provide insights into the potential influence of its microbial community on the parasite's survival. We characterised the intestinal microbiome of T. colubriformis that had been collected from the duodenum of sheep, and compared the helminth microbiome with the duodenal microbiome of its host, aiming to identify contributions from the helminth's environment. At the same time, we explored the isolation of fastidious organisms from the harvested helminth. Primary alpha and beta diversity analyses of bacterial species revealed statistically significant differences between the parasite and the host, in terms of species richness and ecological composition. 16S rRNA differential abundance analysis showed that Mycoplasmoides and Stenotrophomonas were significantly present in T. colubriformis but not in the duodenal microbiome of the sheep. Furthermore, two bacteria, Aeromonas caviae and Aeromonas hydrophila, were isolated from T. colubriformis. Examinations of the genome highlight differences in genome size and profiles of antimicrobial resistance genes. Our results suggest that T. colubriformis carries a specific bacterial community that could be supporting the helminth's long-term survival in the host's digestive system.

Molecular and phylogenetic characterization of zoonotic Trichostrongylus species from goats for the first time in Bangladesh.

BACKGROUND: Trichostrongylus is one of the most important nematodes infecting animals and humans. The current study was designed to identify the Trichostrongylus species infecting goats by multiplex PCR and phylogenetic analysis. METHODS: A total of 124 goats' viscera were collected from different abattoirs of Mymensingh division. Trichostrongylus species were isolated and characterized based on morphometry, multiplex PCR and phylogenetic analysis. RESULTS: Among 124 viscera of goats, 39 were positive with two species, Trichostrongylus colubriformis and Trichostrongylus vitrinus, revealing an overall 31.45% prevalence. Morphological identification of Trichostrongylus species was confirmed by multiplex PCR amplification of the ITS2 gene and sequencing. Partial sequencing of the ITS2 gene of two species revealed seven single nucleotide polymorphisms (three transitions and four transversions) in this study. The neighbor-joining phylogenetic tree demonstrated that T. colubriformis and T. vitrinus isolates were clustered together with the reference sequences that belong to the clade A and B without any geographical boundaries. CONCLUSIONS: This is the first report on molecular and phylogenetic analysis of Trichostrongylus species from ruminants in Bangladesh. These results provide the baseline data for understanding the zoonosis and epidemiology of this parasite in Bangladesh and global perspectives.

Sheep and goat response to Trichostrongylus colubriformis infection based on egg output and worm burden.

This study was aimed to assess the performance of Trichostrongylus colubriformis and the host's responses to regulate egg outputs and worm burden. Infective larva (L3) was prepared by culturing egg of the worms harvested from the intestine of slaughtered sheep. Following this, L3 was maintained in the donor sheep to get adequate quantity of it for experimental trials. A complete randomized block design was used by considering host as blocking factor. Twenty eight small ruminants (sheep = 14) and (goat = 14) were employed in such a way that half of them were drenched with 10,000 T. colubriformis L3 and the remaining halves were controls. Faecal egg count (FEC) was recorded from the initial period (day-zero) up to day-56. At the end of experiment, animals were euthanized in humane manner, worms were recovered from the intestines, counted, and burden was estimated. FEC at various days post infection was insignificantly (P > 0.05) higher in goats than in sheep. The worm burden was significantly (P = 0.040) higher in infected goat than in infected sheep despite they were given equal dose of L3. In conclusion, relatively lower worm burden under natural conditions in goat may be due to their feeding behavior rather than their inherent resistance.

Computed tomography and radioactive 32P detected phosphorus impairment in metabolism, reduced bones density and animal performance caused by mixed infection of Haemonchus contortus and Trichostrongylus colubriformis in sheep.

Phosphorus (P) is one of the main minerals present in the animal body and exerts crucial functions in the organism. P is present at all cell membranes and integrates the structure of bones, being necessary its supplementation in ruminants due to the deficiency of this mineral in the pastures. One of the principal factors that compromise its metabolization are gastrointestinal nematodes (GIN). Thus, the objective of this study was evaluate the performance and metabolism of P through its distribution in the animal body, density of bones and muscles, dynamic fluxes, biological availability and half live of P, concentration of P in tissues and bones of lambs simultaneously infected with the most prevalent GIN to sheep, in tropical or subtropical areas, (Haemonchus contortus and Trichostrongylus colubriformis) using the isotopic dilution technique with 32P radioisotope. Twenty Santa Ines sheep with seven months of age and averaging initial weight of 30.8 ± 6.41 kg were used and allocated to one of two treatments. Ten animals were orally infected (a single dose of 30,000 L3 larvae of T. colubriformis + 10,000 L3 larvae of H. contortus), and ten animals were not infected (control group). During the experimental, samples of blood, feces, urine, and diet refusals were collected and weighting were performed. A computed tomography was performed twice, before infection and at the end of the experiment, to evaluate changes in body composition. On 64-d after experimental infection, animals received an intravenous injection of 32P solution, and 7-d after they received radioisotope injection. The experimental animals were slaughtered, and tissue and bones were collected for P concentrations. The results showed that the parasitic infection compromised the absorption of P, impairing the metabolism, decreasing the mineral bioavailability increasing P bones reabsorption, and reducing bones density, also negatively compromising the infected animal performance.

Trichostrongylus colubriformis infection damages intestine brush board cells and could negatively impact postabsorptive parameters of Santa Ines lambs.

This study aimed to evaluate histological, digestive and postabsorptive physiological parameters in Santa Ines lambs infected with Trichostrongylus colubriformis and fed different levels of phosphorus. Therefore, eighteen Santa Ines, castrated male, six-month old, healthy lambs (initial body weight 22.4 ± 2.7 kg) were distributed in one of four treatments arranged in a 2 × 2 split-plot arrangement: Sufficient dietary P level and uninfected (SPui; n = 4), Sufficient dietary P level and infected (SPi; n = 5), Deficient dietary P level and uninfected (DPui; n = 4), Deficient dietary P level and infected (DPi; n = 5). Infected lambs received, orally, a single pulse dose of 40.000 T. colubriformis infective larval stage (L3). Animals were fed Tifton 85 hay (Cynodon ssp.; 60%), and cassava meal and maize gluten meal (40%). Measurement of nutrient apparent digestibility and nitrogen metabolism were performed in individual metabolic stalls. To achieve the trial results, it was measured methane emissions in respiratory chambers, urine purine derivatives, ruminal short-chain fatty acids (SCFA), histological cuts of duodenal mucosal tissues and passage rates fluxes, analyzed by external (Yb, Cr, and Co) and internal (iNDF) markers. Statistical procedures were performed in R studio. The fixed main effects of treatment and the interactions were tested by ANOVA, and means compared by Duncan's test at 5% significance. Apparent digestibility was not affected by treatments, however, nitrogen retained decreased (P < 0.01) and urinary nitrogen losses increased (P < 0.01) in infected animals. Small intestine digesta content, empty segment weight, and length were higher in infected animals (P < 0.05). Passage rate was not majorly affected by infection or dietary P levels. Methane emissions, SCFA concentrations, and purine derivative excretion were also not affected by treatments. Regarding the histology, the vilosity weight (P < 0.05), and crypt depth (P < 0.01) decreased in infected animals. In conclusion, T. colubriformis infection can damage intestinal mucosa and affect nitrogen metabolism, but did not affect the digesta transit, and nutrient digestibility. The P dietary levels did not promote any modification in GIT physiological parameters tested in this study.

Performance of lambs under four levels of dietary supplementation and artificially mix-infected with Haemonchus contortus and Trichostrongylus colubriformis.

The effect of four diets on the performance of Dorper lambs that were artificially mix-infected with 1000 infective larvae (L3) of Haemonchus contortus and 1000 L3 of Trichostrongylus colubriformis every three days for 12 weeks was evaluated. For each diet, one infected group (n = 7) and one control group (n = 4) were set up. The four diets contained the following proportions of hay (H) and concentrate (C): Diet 1 - 100%H; Diet 2 - 75%H:25%C; Diet 3 - 50%H:50%C; Diet 4 - 25%H:75. All the infected groups showed decreases in mean packed cell volume (PCV) and total plasma protein, especially the Diet 1-infected, which was also the group with the highest fecal egg count. The diets and infection had significant effects (P < 0.05) on daily body weight gain (DBWG), cold carcass weight and daily food consumption. The control and infected groups had mean DBWG (in kg), respectively, of 0.048 and 0.025 with Diet 1; 0.082 and 0.067 with Diet 2; 0.188 and 0.189 with Diet 3; and 0.303 and 0.221 with Diet 4. In conclusion, the infection affected the productive performance regardless of the diet; however, with increased metabolizable protein and energy, the risk of occurrence of anemia and hypoproteinemia diminished.

Trichostrongylus colubriformis affecting sheep phosphorus metabolism and precision feeding as a mitigating strategy.

This review details the negative effects of Trichostrongylus colubriformis infection in sheep phosphorus metabolism and direct and indirect impacts from high excretion from susceptible animals, as well as the advantages offered by precision feeding as potential strategies to mitigate loss. In sheep infected with T. colubriformis there is a high reduction in P bioavailability, because of depression in the absorptive capacity of this mineral, affecting the absorption and recycling of P to the digestive tract, causing mineral deficiency. Therefore, precision feeding compiles animal genetics information, feeding type and grazing management to control animal feed intake and quantity and quality of manure produced. In this sense, the adoption of precision feeding can provide a better arrangement of the information, making sheep production more economically, socially and environmentally sustainable.

Prevalence of trichostrongylus in sheep in the district Zhob, Balochistan, Pakistan / [Prevalência de trichostrongylus em ovelhas no distrito Zhob, Balochistão, Paquistão]

Trichostrongylid em ovelhas foi estudado no Distrito Zhob, Balochistan. Foram coletados 120 tratos gastrointestinais (GIT) de ovelhas do matadouro do distrito. Estas amostras foram processadas para isolamento e identificação de nematódeos tricostrônquicos no Laboratório do Hospital Veterinário do Distrito Zhob. A taxa de prevalência geral foi de 39,1% em machos e 60,8% em fêmeas (p=0,001). A taxa de prevalência em duas raças viz Balochi e Rakhshani foi de 58,3% e 41,6%, respectivamente (p=0,01). A prevalência da espécie observada com Trichostrongylus foi 19,1%, Haemonchus foi 20,8%, Cooperia foi 29,1% e Nematodirus foi 30,8% (p=0,087). Quanto a quantidade de espécies infestadas pelas ovelhas, um único tipo de parasita estava em 32,5% de animais, dois tipos de espécies parasitárias em 36,3% dos animais e três tipos de espécies parasitárias em 30,8% dos animais (p=0,366).(AU)

Performance of lambs under four levels of dietary supplementation and artificially mix-infected with Haemonchus contortus and Trichostrongylus colubriformis / Efeito de quatro dietas na performance de cordeiros artificialmente infectados com Haemonchus contortus e Trichostrongylus colubriformis

Abstract The effect of four diets on the performance of Dorper lambs that were artificially mix-infected with 1000 infective larvae (L3) of Haemonchus contortus and 1000 L3 of Trichostrongylus colubriformis every three days for 12 weeks was evaluated. For each diet, one infected group (n = 7) and one control group (n = 4) were set up. The four diets contained the following proportions of hay (H) and concentrate (C): Diet 1 - 100%H; Diet 2 - 75%H:25%C; Diet 3 - 50%H:50%C; Diet 4 - 25%H:75. All the infected groups showed decreases in mean packed cell volume (PCV) and total plasma protein, especially the Diet 1-infected, which was also the group with the highest fecal egg count. The diets and infection had significant effects (P < 0.05) on daily body weight gain (DBWG), cold carcass weight and daily food consumption. The control and infected groups had mean DBWG (in kg), respectively, of 0.048 and 0.025 with Diet 1; 0.082 and 0.067 with Diet 2; 0.188 and 0.189 with Diet 3; and 0.303 and 0.221 with Diet 4. In conclusion, the infection affected the productive performance regardless of the diet; however, with increased metabolizable protein and energy, the risk of occurrence of anemia and hypoproteinemia diminished.

Resumo Avaliou-se o efeito de quatro dietas sobre o desempenho de cordeiros Dorper infectados artificialmente, a cada três dias, durante 12 semanas, com 1.000 larvas infectantes (L3) de Haemonchus contortus e 1.000 L3 de Trichostrongylus colubriformis. Um grupo infectado (n=7) e um controle (n=4) foram constituídos para cada uma das dietas, que continham a seguinte proporção de feno (F) e concentrado (C): Dieta 1 - 100%F; Dieta 2 - 75%F:25%C; Dieta 3 - 50%F:50%C; Dieta 4 - 25%F:75%C. Todos os grupos infectados apresentaram redução nas médias de hematócrito (VG) e proteína plasmática total (PPT), principalmente o grupo Dieta 1 infectado, que também apresentou maior contagem de ovos nas fezes. Houve efeito significativo da dieta e da infecção (P <0,05) no ganho em peso médio diário, peso da carcaça e consumo diário de alimento. Os grupos controle e infectado tiveram ganho em peso médio diário (em kg), respectivamente, de 0,048 e 0,025 na Dieta 1; 0,082 e 0,067 na Dieta 2; 0,188 e 0,189 na Dieta 3; e 0,303 e 0,221 na Dieta 4. Concluiu-se que a infecção afetou o desempenho produtivo independentemente da dieta, porém, com o aumento da proteína e da energia metabolizável, o risco de ocorrência de anemia e hipoproteinemia diminuiu.

Trichostrongylus colubriformis affecting sheep phosphorus metabolism and precision feeding as a mitigating strategy / Trichostrongylus colubriformis afetando o metabolismo do fosforo em ovinos e alimentação de precisão como estratégia de mitigação

Abstract This review details the negative effects of Trichostrongylus colubriformis infection in sheep phosphorus metabolism and direct and indirect impacts from high excretion from susceptible animals, as well as the advantages offered by precision feeding as potential strategies to mitigate loss. In sheep infected with T. colubriformis there is a high reduction in P bioavailability, because of depression in the absorptive capacity of this mineral, affecting the absorption and recycling of P to the digestive tract, causing mineral deficiency. Therefore, precision feeding compiles animal genetics information, feeding type and grazing management to control animal feed intake and quantity and quality of manure produced. In this sense, the adoption of precision feeding can provide a better arrangement of the information, making sheep production more economically, socially and environmentally sustainable.

Resumo Essa revisão detalha os efeitos negativos da infecção por Trichostrongylus colubriformis no metabolismo do fósforo de ovinos e os impactos diretos e indiretos da alta excreção em animais susceptíveis, bem como as vantagens oferecidas pela alimentação de precisão como estratégia potencial para mitigar perdas. Em ovinos infectados com T. colubriformis há uma alta redução na biodisponibilidade de P, devido à depressão na capacidade de absorção desse mineral, afetando a absorção e a reciclagem de P no trato digestivo, causando deficiência mineral. Portanto, a alimentação de precisão compila informações de genética animal, tipo de alimentação e manejo da pastagem para controlar o consumo de alimento e a quantidade e qualidade dos dejetos produzidos. Nesse sentido, a adoção da alimentação de precisão pode proporcionar um melhor arranjo das informações, tornando a produção de ovinos mais econômica, social e ambientalmente sustentável.

Isolation of pure Trichostrongylus colubriformis strains from naturally infected sheep using two methodologies.

Two methodologies were tested to isolate pure Trichostrongylus colubriformis strains from naturally infected sheep. Also, the in vitro susceptibility status to commercial anthelmintic (AH) drugs was determined in these strains. These methods were performed in a tropical region of Mexico where naturally infected sheep and goats host Haemonchus contortus, T. colubriformis and Oesophagostomum columbianum. For the first strain, a group of 6 naturally infected lambs from the "Paraiso" farm were treated with closantel (subcutaneous (SC), 10 mg/kg). On day 10 post-treatment, the eggs per gram (EPG) of faeces were determined with the McMaster technique. The faeces from the two lambs with the highest EPG were used for coprocultures (4 days, 28 °C). The L3 larvae were recovered and identified as T. colubriformis (69%) and O. columbianum (31%). The latter was removed by 10-day refrigeration (4-5 °C) followed by sieving (25 µm), resulting in 100% T. colubriformis (PARAISO strain). The second strain was isolated using repeated doses of levamisole (LEV, SC 7.5 mg/kg) in an 8-year-old sheep. The sheep had 1700 EPG before the LEV treatments and maintained 1300 EPG after both LEV treatments (day 10). The coproculture (4 days, 28 °C) after the second treatment contained 100% T. colubriformis (FMVZ-UADY strain). The in vitro AH susceptibility was determined using the egg hatch test for benzimidazole (BZ), and the larval migration inhibition test for ivermectin (IVM) and LEV. The PARAISO strain was BZ- and LEV-susceptible, and IVM-resistant. Meanwhile, the FMVZ-UADY strain was BZ- and IVM-susceptible, and LEV-resistant. The conditions where these two protocols could be used in other parts of the world were discussed.

Phylogenetic analysis of Trichostrongylus vitrinus isolates from southwest Iran.

BACKGROUND: Trichostrongylus is one of the most important zoonotic trichostrongylid nematodes, infecting mostly livestock. Data on its genetic characteristics are lacking in Iran. METHODS: We determined the phylogenetic relationships of Trichostrongylus species in three counties of Kohgiloyeh and Boyerahmad (K-B) province, southwest Iran. Small intestine and abomasum of 70 sheep and goats were investigated. RESULTS: A total of 35 isolates of Trichostrongylus worms were detected and all were genetically identified as Trichostrongylus vitrinus. Analysis of 321 bp of the internal transcribed spacer 2 (ITS2) of ribosomal DNA revealed 16 genotypes. All genotypes were single nucleotide polymorphisms, including some hypervariable points. All sequences were trimmed to 170 bp, compared with sequences on GenBank including short sequences from other endemic foci of Iran and other countries and all isolates were used to generate a maximum likelihood phylogenetic tree, which consisted of two clades A and B. Clade A included isolates from Iran, Russia, New Zealand, Australia and the UK; clade B only contained South African isolates. Most clade A isolates (north, southwest and west Iran, Russia, New Zealand, Australia and UK) were in a similar phylogenetic position. One subclade was detected in clade A (isolates from Southwest Iran, New Zealand and UK). CONCLUSIONS: We hypothesize that drug resistant T. vitrinus may account for its exclusive detection in our samples. The high similarity of genotypes from Iran, New Zealand and UK may be due to their close political relationships during the colonial era. More research is needed to understand better the phylogeny of T. vitrinus and its relationship with drug resistance and human transmission.

Feeding of carob (Ceratonia siliqua) to sheep infected with gastrointestinal nematodes reduces faecal egg counts and worm fecundity.

The present study explored the anthelmintic effects of condensed tannins (CT) in carob (Ceratonia siliqua) pods fed to sheep against gastrointestinal nematodes. Three independent in vivo trials tested whether i) carob pod (CaBP)-containing feed had an anthelmintic effect and if yes, which was the optimal concentration in the diet; ii) whether this effect could be attributed to tannins through the polyethylene glycol (PEG) test and iii) whether there were any synergistic effects when combined with another tannin-containing feed (e.g. sainfoin). In all trials 6-month old nematode-naive lambs, experimentally infected with both Haemonchus contortus and Trichostrongylus colubriformis, were used. Faecal egg counts (FEC) were performed regularly and at the end of each trial adult worm counts (AWC) and female worm fecundity were recorded. In trial 1, 35 lambs (five groups of seven lambs) were fed different CaBP concentrations ranging from 0% to 12 % w/w. FEC declined up to 39.2 % only in the group fed with 12 %CaBP, while a declining trend (P < 0.06) was demonstrated for the AWC of T. colubriformis, which was associated with the increasing concentration of CaBP in feed. Female worm fecundity was reduced in groups fed CaBP for both parasites, however this was only significant for H. contortus (P < 0.001), in a dose dependent manner. In trial 2, four groups of six infected lambs each were used, which received the carob diets CaBP or CaBP + PEG, and the tannin-free diets with or without PEG (C or C + PEG). Results showed that FEC of Groups C, C + PEG, and CaBP + PEG were comparable throughout the trial, while the group receiving only CaBP showed lower FEC from DAY 25 onwards. AWC showed a reduction (67.7 %) only for H. contortus (P < 0.03). Reversal of the anthelmintic effect of CaBP after PEG administration suggested that CT contributed to the anthelmintic action. However, no effect of CaBP was observed on T. colubriformis AWC and on female worm fecundity for both species. Finally, for trial 3 four groups of six lambs each received a diet based on CaBP, sainfoin (S) or a combination (CaBP + S) and were compared to a control (C) diet of lucerne. On DAY 37 FEC values in groups CaBP + S and S tended to be lower compared to the two other groups (C, CaBP), while for AWCs no significant differences were observed for both parasites. The fecundity of H. contortus and T. colubriformis demonstrated significant differences between the treated and control groups, with lower values in the animals receiving CaBP + S. Overall, the results supported the hypothesis that carob had an anthelmintic effect due to its CT, but there was no clear indication of a synergistic effect with sainfoin.

Chemical characterization and in vitro biological activity of Cymbopogon citratus extracts against Haemonchus spp. and Trichostrongylus spp. nematodes from sheep.

Medicinal plants have been the focus of several studies due to their nematicide properties which can be used to control nematodes in sheep. No study has examined the morphological effects of Cymbopogon citratus on nematodes. Thus, this study evaluated the chemical composition, nematicidal activity and effects of C. citratus extracts on the morphology of eggs and infective larvae (L3) of sheep. Aqueous and methanolic extracts and fractions of C. citratus were obtained and analysed in vitro. The C. citratus extracts were effective against Haemonchus spp. and Trichostrongylus spp. larvae and eggs. Ten fractions were obtained from C. citratus, six of which had high ovicidal activity at 1000 µg mL-1, and two fractions had high activity at all tested concentrations. The phytochemical analysis identified the presence of compounds such as terpenoids, various ketones, esters, and fatty acids. The ultrastructural analysis showed deformations of the cuticle and wilting along the body of the nematodes at all concentrations. The muscular layer, intestinal cells and the mitochondria profile showed damage compared to the typical pattern. Ultra-thin sections of eggs treated with methanolic fractions of C. citratus presented modifications. This study showed the biological activity and effects of C. citratus on the gastrointestinal nematodes in sheep.

Attempts to induce tolerance to Trichostrongylus colubriformis infection in sheep.

BACKGROUND AND OBJECTIVES: The possibility of manipulating the immune response in lambs to the gastrointestinal nematode Trichostrongylus colubriformis to reduce production losses associated with infection was investigated. In a series of four experiments, attempts to immunize sheep via the mucosal route to modify the immune response and induce mucosal tolerance are outlined. Initially, a proof of concept study was conducted with lambs being injected with multiple doses of a somatic T colubriformis antigen without an adjuvant in the rectal submucosa and subsequently challenged with T colubriformis L3 larvae. This was followed by a dose-response study comparing different antigen doses to identify the optimum dose of the nematode antigen for successful induction of mucosal tolerance. The final two studies were conducted to determine the larval stage specificity of the parasite antigen and the most suitable site of delivery required to stimulate mucosal tolerance. METHODS: In the proof of concept study, lambs either received repeated injections in the rectal submucosa at 3 × weekly intervals with 15 µg of L3, 11 µg of L4 and 21 µg of immature adult (L5) somatic T colubriformis antigens (ANT) or not (INF) prior to infection with T colubriformis. In the dose-rate study, antigen dose rates of 100%, 50%, 10%, 1% or 0% of the antigen concentration used in the proof of concept study were compared while the larval stage study compared antigen from either L3, L4, L5 stages or combination of all (COMB) and the route of administration study compared antigen delivery into either the rectal submucosa (RE) or sub-cutaneous injection (SC). RESULTS: During infection, lamb growth was improved by antigen treatment between days 21 and 42 in the proof of concept study (P = .009), for groups 10%, 50% and 100% in the dose-rate study (P < .05 for all) and in RE in the route of administration study with no improvement observed in the larval stage study. No differences in faecal egg counts were observed (P > .05 for all). Parasite-specific IgA and IgE showed a dose-response (the dose-rate study), were not affected by larval stage (the larval stage study) and were greater in RE than SC (the route of administration study). IL-4 production following lymphocyte stimulation was greatest in COMB (the larval stage study) and RE (the route of administration study). CONCLUSIONS: Although antigen treatment improved performance, this was inconsistent and appeared to stimulate immunity rather than induce tolerance. Combined larval stages were more efficient than individual stages, and intra-rectal administration was more effective than sub-cutaneous.

The potential for vaccines against scour worms of small ruminants.

This review addresses the research landscape regarding vaccines against scour worms, particularly Trichostrongylus spp. and Teladorsagia circumcincta. The inability of past research to deliver scour-worm vaccines with reliable and reproducible efficacy has been due in part to gaps in knowledge concerning: (i) host-parasite interactions leading to development of type-2 immunity, (ii) definition of an optimal suite of parasite antigens, and (iii) rational formulation and administration to induce protective immunity against gastrointestinal nematodes (GIN) at the site of infestation. Recent 'omics' developments enable more systematic analyses. GIN genomes are reaching completion, facilitating "reverse vaccinology" approaches that have been used successfully for the Rhipicephalus australis vaccine for cattle tick, while methods for gene silencing and editing in GIN enable identification and validation of potential vaccine antigens. We envisage that any efficacious scour worm vaccine(s) would be adopted similarly to "Barbervax™" within integrated parasite management schemes. Vaccines would therefore effectively parallel the use of resistant animals, and reduce the frequency of drenching and pasture contamination. These aspects of integration, efficacy and operation require updated models and validation in the field. The conclusion of this review outlines an approach to facilitate an integrated research program.

Trichostrongylus colubriformis infection in Santa Inês lambs: impact on feed digestibility, blood markers, and nitrogen balance.

This study aimed to evaluate the effects of Trichostrongylus colubriformis infection on the hemato-biochemical parameters, feed digestibility, and nitrogen balance in Santa Inês lambs. Eighteen three-month-old Santa Ines castrated male lambs (16.9 ± 1.43 kg of body weight) were randomly distributed in two experimental treatments: infected with T. colubriformis (I, n = 9) and uninfected (U, n = 9). The I group received a total of 45,000 L3 larvae of T. colubriformis (5,000 infective larvae, three times per week, for three weeks). During the experimental period, blood, feed digestibility, and nitrogen balance were evaluated. The I lambs showed a reduction in erythrocytes, hemoglobin, hematocrit, mean corpuscular volume, and total proteins, as well as an increase in platelets and eosinophils compared to those in the U group (p < 0.05). With the exception of total protein content, these values were within the normal range for the species. Furthermore, lower dry matter and organic matter digestibility were observed in the I lambs (p = 0.08). The present findings highlight that T. colubriformis infection has the potential to impair some hemato-biochemical parameters as well as feed digestibility in lambs, which could affect their productivity.

Trichostrongylus colubriformis infection in Santa Inês lambs: impact on feed digestibility, blood markers, and nitrogen balance / Infecção por Trichostrongylus colubriformis em cordeiros Santa Inês: impacto na digestibilidade dos alimentos, marcadores sanguíneos e balanço de nitrogênio

Abstract This study aimed to evaluate the effects of Trichostrongylus colubriformis infection on the hemato-biochemical parameters, feed digestibility, and nitrogen balance in Santa Inês lambs. Eighteen three-month-old Santa Ines castrated male lambs (16.9 ± 1.43 kg of body weight) were randomly distributed in two experimental treatments: infected with T. colubriformis (I, n = 9) and uninfected (U, n = 9). The I group received a total of 45,000 L3 larvae of T. colubriformis (5,000 infective larvae, three times per week, for three weeks). During the experimental period, blood, feed digestibility, and nitrogen balance were evaluated. The I lambs showed a reduction in erythrocytes, hemoglobin, hematocrit, mean corpuscular volume, and total proteins, as well as an increase in platelets and eosinophils compared to those in the U group (p < 0.05). With the exception of total protein content, these values were within the normal range for the species. Furthermore, lower dry matter and organic matter digestibility were observed in the I lambs (p = 0.08). The present findings highlight that T. colubriformis infection has the potential to impair some hemato-biochemical parameters as well as feed digestibility in lambs, which could affect their productivity.

Resumo O objetivo deste estudo foi avaliar os efeitos da infecção por Trichostrongylus colubriformis nos parâmetros hemato-bioquímicos, digestibilidade aparente dos nutrientes e balanço de nitrogênio de cordeiros Santa Inês. Dezoito cordeiros Santa Inês, de três meses de idade e castrados (16,9 ± 1,43 kg de peso corporal), foram distribuídos aleatoriamente em dois tratamentos experimentais: infectados com T. colubriformis (I, n = 9) e não infectados (U, n = 9). O grupo I recebeu um total de 45.000 larvas L3 de T. colubriformis (5.000 larvas infectantes, três vezes por semana, durante três semanas). Durante o período experimental, foram avaliadas as variáveis sanguíneas, digestibilidade e balanço de nitrogênio. Os cordeiros I apresentaram redução de eritrócitos, hemoglobina, hematócrito, volume corpuscular médio e proteínas totais, além de aumento de plaquetas e eosinófilos, quando comparados ao grupo U (p< 0,05). Contudo, exceto para proteínas totais, os valores estavam dentro do intervalo normal para a espécie. Além disso, a digestibilidade da matéria seca e da matéria orgânica foi menor no grupo I de cordeiros (p = 0,08). Os presentes achados destacam que a infecção por T. colubriformis teve potencial para prejudicar alguns parâmetros hemato-bioquímicos, bem como a digestibilidade aparente da dieta, o que poderia afetar a produtividade dos cordeiros.

Losses caused by gastrointestinal nematode infections in Dorper lambs under two nutritional status / Prejuízos causados pelas infecções por nematoides gastrintestinais em cordeiros Dorper submetidos a dois manejos nutricionais

Abstract The aim of this study was to evaluate the effect of two nutritional statuses on the productive performance of Dorper lambs naturally infected with gastrointestinal nematodes. Thirty-two lambs, grazing together on the same pasture, were allocated into four experimental groups: (G1) infected-supplemented diet, (G2) control-supplemented diet, (G3) infected-basal diet, and (G4) control-basal diet. Control animals received suppressive treatment with monepantel every two weeks, while precautionary anthelmintic treatments were given to all lambs of the infected groups with packed cell volume (PCV) <23%. There was reduction in the PCV means of all groups, which was more pronounced in the infected lambs that also presented reduction in total plasma protein values in comparison with the controls. Weight gain was affected by diet and infection status (P < 0.05). Daily body weight gain was 0.170 kg in the G1, 0.205 kg in the G2, 0.085 kg in the G3, and 0.116 kg in the G4. The cold carcass weight was 4.1% and 13.7% higher in controls in comparison with infected lambs, respectively, in the supplemented and basal diets. The infected groups, despite receiving precautionary anthelmintic treatments to prevent deaths due to haemonchosis, presented reduction in the production parameters in comparison with the controls.

Resumo O experimento teve por objetivo determinar o efeito de dois níveis de nutrição no desempenho produtivo de cordeiros Dorper naturalmente infectados por nematoides gastrintestinais. Trinta e dois cordeiros, mantidos juntos na mesma pastagem, foram alocados em quatro grupos experimentais: (G1) infectado-suplementado, (G2) controle-suplementado, (G3) infectado-dieta basal e (G4) controle-dieta basal. Os cordeiros suplementados receberam diariamente concentrado em quantidade equivalente a 2% do peso corporal (PC), enquanto na dieta basal receberam apenas uma pequena quantidade de concentrado (0,35% do PC). Os animais controles receberam tratamento supressivo com anti-helmíntico a cada duas semanas e os infectados foram tratados individualmente quando apresentaram volume globular (VG) <23%. Houve redução nas médias de VG em todos os grupos, as quais foram mais pronunciadas nos animais dos grupos infectados, que também apresentaram redução nos valores de proteína plasmática total em comparação com os controles. Houve efeito significativo da dieta e da infecção no ganho de peso (P <0,05). O ganho em peso diário foi de 0,170 kg no G1, 0,205 kg no G2, 0,085 kg no G3 e 0,116 kg no G4. Os grupos infectados, apesar de receberem tratamentos anti-helmínticos preventivos que evitaram mortes por haemonchose, apresentaram redução nos parâmetros produtivos em comparação com os controles.

Losses caused by gastrointestinal nematode infections in Dorper lambs under two nutritional status.

The aim of this study was to evaluate the effect of two nutritional statuses on the productive performance of Dorper lambs naturally infected with gastrointestinal nematodes. Thirty-two lambs, grazing together on the same pasture, were allocated into four experimental groups: (G1) infected-supplemented diet, (G2) control-supplemented diet, (G3) infected-basal diet, and (G4) control-basal diet. Control animals received suppressive treatment with monepantel every two weeks, while precautionary anthelmintic treatments were given to all lambs of the infected groups with packed cell volume (PCV) <23%. There was reduction in the PCV means of all groups, which was more pronounced in the infected lambs that also presented reduction in total plasma protein values in comparison with the controls. Weight gain was affected by diet and infection status (P < 0.05). Daily body weight gain was 0.170 kg in the G1, 0.205 kg in the G2, 0.085 kg in the G3, and 0.116 kg in the G4. The cold carcass weight was 4.1% and 13.7% higher in controls in comparison with infected lambs, respectively, in the supplemented and basal diets. The infected groups, despite receiving precautionary anthelmintic treatments to prevent deaths due to haemonchosis, presented reduction in the production parameters in comparison with the controls.