Gastrointestinal Nematode Parasites Research Articles

Using the fungus Arthrobotrys cladodes var. macroides as a sustainable strategy to reduce numbers of infective larvae of bovine gastrointestinal parasitic nematodes.

Research in the area of sanitation in ruminant production has focused on discovery of potential agents for biological control of helminths with nematophagous fungi and has provided evidence of success. The antagonistic potential of the fungus Arthrobotrys cladodes var. macroides on infective larvae of bovine gastrointestinal parasitic nematodes was evaluated by scanning electron microscopy. Additionally, an in vivo test of the resistance to digestive processes and viability of the fungus was carried out using a formulation based on sodium alginate administered orally in cattle. Production of conidia and chlamydospores was high. In in vitro tests, the number of infective nematode larvae was reduced 68.7% by the fungus in the treated group compared to the control group. The interaction between the fungus and the nematodes was confirmed by scanning electron microscopy. Plates containing fecal samples collected after oral administration of 100 g of pellets containing the A. cladodes fungus showed that the fungus survived passage through the gastrointestinal tract of ruminants, grew on agar, formed traps and preyed on L3 larvae of gastrointestinal parasites. The results of the present study provide a new opportunity for alternative, environmentally safe control of ruminant nematodes.

Correlation of carbohydrate larval antigen (CarLA®) antibody response with parasitism in Ontario sheep

Gastrointestinal nematode parasites (GINs) are a significant cause of morbidity, mortality and loss of productivity on North American sheep farms. In light of the rising prevalence of anthelmintic resistance, selection of animals with a superior immune response to GINs has received considerable attention. In New Zealand, measurement of salivary antibody to a carbohydrate larval antigen (CarLA®, AgResearch Inc.) has been used successfully to identify sheep with superior immunity. However, climate and GIN epidemiology in Ontario are different from New Zealand, and sheep are generally not exposed to GINs for several months during housing over winter. To date, CarLA® has not been evaluated in North America. The purpose of this study was to determine whether Car LA® correlates with parasite burden under temperate grazing conditions in Ontario.

Influence of the physiological stage of Blackbelly sheep on immunological behaviour against gastrointestinal nematodes

The influence of the physiological stage of a Blackbelly flock against natural infection by gastrointestinal parasitic nematodes (GIN) was investigated. Data on serum and saliva IgA levels and peripheral cellular immune response were recorded in 51 sheep for 6 months. The flock was divided based on their physiological stage as follows: a) pregnant ewes, b) lactating ewes, c) non-pregnant ewes, d) pre-weaning lambs, e) growing lambs and f) replacement sheep. Additionally, sheep were classified based on the parasite infection as stabled or grazing management system as follows: g) non-infected stabled sheep, h) infected and stabled sheep and i) infected grazing sheep. Faeces and blood samples were collected every fifteen days. The percentage of packed cell volume (PCV), plasma protein, (PP) and leucocyte differential counts (LDC) were recorded. Likewise, serum and saliva IgA levels were measured by the indirect ELISA technique. The number of GIN eggs excreted per g of faeces (EPG) was also determined using the McMaster technique. Data were analysed using the SAS program to identify fixed effect of physiological stages, infection time and interactions. Results showed high EPG values in stabled lactating ewes (2764) and in growing lambs (2950–4550 EPG). Pregnant ewes had higher PCV values (27%) than lactating ewes (23.5%). Infected lambs showed low PCV values (28.5%) and high PP values (5.9 g/dL) compared with non-infected lambs (31% PCV and 5.6 g/dL PP). The two most abundant GIN species identified were Haemonchus contortus (91%) and Trichostrongylus colubriformis (81%). Pregnant and non-pregnant ewes showed 29% and <20% of IgA values, respectively. High EPG, low IgA and eosinophils counts were observed until 180 days of age in infected lambs. In conclusion, the group of infected lactating ewes and lambs showed susceptibility to GIN than the other groups, including the pregnant ewes.

Immunity to gastrointestinal nematodes in ruminants: effector cell mechanisms and cytokines.

Gastrointestinal nematodes (GINs) of ruminants are prevalent and have major economic impacts worldwide. The insight studies of immune responses triggered against GINs are of great concern to understand interaction between host's immune system and parasite. T-helper 2 cytokines drive the effector cell mechanisms which include eosinophils and mast cells. The immune responses are controlled by Th2 secreted interleukins (IL); IL3, IL-4, IL-5, IL-9, IL-10 and IL-13. B-Cell immune response is incorporated in defense mechanisms developed against GINs specially immunoglobulins (Ig); IgA, IgE and IgG. The immune resistance of the infected host is presented by failure of larval establishment or hypobiosis, low worm burden and decreased female fecundity. The host-parasite interaction is a complex series that affected by host's genetic constitution, nutrition, age and physiological status. The GINs have different immune evasion mechanisms to improve their survival within the host. Also, management of the host influences GINs parasitism. Thus, the aim of this review is to highlight the hallmarks of immune responses that endorse GINs parasitism. The insights studies of the triggered immune responses developed against GINs will improve the appropriate protective immune strategy.

Droplet digital polymerase chain reaction (ddPCR) as a novel method for absolute quantification of major gastrointestinal nematodes in sheep

In this paper, we present for the first time a new tool, based on Droplet Digital™ Polymerase Chain Reaction (ddPCR), for absolute quantification of key genera of gastrointestinal (GI) nematode parasites of grazing livestock. Four combinations of primers/probe sets targeting the internal transcribed spacer region 2 (ITS2) of the ribosomal RNA gene array were designed using the Primer3 software, following in silico analysis of nucleotide sequences from nematodes of interest downloaded from common databases. The amplified regions include both a universal region for detection of any strongylid gastrointestinal parasite and three different genus specific regions, making it possible to differentiate between the most important GI nematodes of sheep in Sweden: Haemonchus, Teladorsagia and Trichostrongylus. Analysis of samples containing serial dilutions and different mixtures of genomic DNA extracted from different species of adult worms proved useful in assessment of different threshold settings with the QuantaSoft software. Analysis of template DNA from these worms indicated that ddPCR is a viable choice for detection and absolute quantification of the different genera and also in samples with multiple species. Interpretation of the ddPCR results was straightforward and choice of analytical approach had little influence on the final results. Thus, the results obtained in the different analytical approaches seemed to be robust and the concentrations determined were uniform. Furthermore, the linear range of the Haemonchus ddPCR assay was similar to that of real-time PCR (qPCR). Taken together, our data confirm the suitability of ddPCR for detection and absolute quantification of three major sheep pathogens when tested on larval cultures from pooled ovine faeces. The results also indicate that ddPCR can be a useful complement to applications based on conventional egg counting methods such as the faecal egg reduction test (FECRT).

Field evaluation of Duddingtonia flagrans IAH 1297 for the reduction of worm burden in grazing animals: Pasture larval studies in horses, cattle and goats

A series of placebo-controlled trials were conducted in horses, cattle and goats in different seasons and bioclimatic regions of New South Wales and Queensland, Australia, to evaluate the ability of BioWorma®, a feed supplement containing the spores of Duddingtonia flagrans IAH 1297, to reduce the larval development of parasitic gastrointestinal nematodes (GIN) and their subsequent migration from faeces onto the surrounding pasture.In each trial, faeces were collected from animals harbouring a burden of nematode parasites following a period of supplementation with a placebo and again after supplementation with BioWorma. The faeces were manually placed onto pasture plots at one or two distinct geographical sites and the effect of treatment was determined by subsequent monitoring the numbers of parasitic larvae on the pasture surrounding the faecal pats at two weekly intervals over an eight week period. The results for these studies showed that administration of BioWorma at a minimum daily dose of 3 × 104 spores/kg bodyweight reduced parasite larvae in the pasture surrounding the faeces by 53–99 % over an eight week post treatment period in horses, cattle and goats in a range of bioclimatic zones and in different seasons.Overall, the studies with BioWorma show substantial reductions in GIN infectivity of pasture surrounding faeces of treated horses, cattle and goats (P < 0.05). Results indicate that the use of BioWorma in these host species would lead to decreased levels of GIN infection in animals grazing pasture when this product is used and would provide an alternative means of controlling parasitic nematodes.

Ram sperm production estimates

The influence of the physiological stage of a Blackbelly flock against natural infection by gastrointestinal parasitic nematodes (GIN) was investigated. Data on serum and saliva IgA levels and peripheral cellular immune response were recorded in 51 sheep for 6 months. The flock was divided based on their physiological stage as follows: a) pregnant ewes, b) lactating ewes, c) non-pregnant ewes, d) pre-weaning lambs, e) growing lambs and f) replacement sheep. Additionally, sheep were classified based on the parasite infection as stabled or grazing management system as follows: g) non-infected stabled sheep, h) infected and stabled sheep and i) infected grazing sheep. Faeces and blood samples were collected every fifteen days. The percentage of packed cell volume (PCV), plasma protein, (PP) and leucocyte differential counts (LDC) were recorded. Likewise, serum and saliva IgA levels were measured by the indirect ELISA technique. The number of GIN eggs excreted per g of faeces (EPG) was also determined using the McMaster technique. Data were analysed using the SAS program to identify fixed effect of physiological stages, infection time and interactions. Results showed high EPG values in stabled lactating ewes (2764) and in growing lambs (2950–4550 EPG). Pregnant ewes had higher PCV values (27%) than lactating ewes (23.5%). Infected lambs showed low PCV values (28.5%) and high PP values (5.9 g/dL) compared with non-infected lambs (31% PCV and 5.6 g/dL PP). The two most abundant GIN species identified were Haemonchus contortus (91%) and Trichostrongylus colubriformis (81%). Pregnant and non-pregnant ewes showed 29% and <20% of IgA values, respectively. High EPG, low IgA and eosinophils counts were observed until 180 days of age in infected lambs. In conclusion, the group of infected lactating ewes and lambs showed susceptibility to GIN than the other groups, including the pregnant ewes.

Comparison of fecal egg counting methods in four livestock species

Gastrointestinal nematode parasites are important pathogens of all domesticated livestock species. Fecal egg counts (FEC) are routinely used for evaluating anthelmintic efficacy and for making targeted anthelmintic treatment decisions. Numerous FEC techniques exist and vary in precision and accuracy. These performance characteristics are especially important when performing fecal egg count reduction tests (FECRT). The objective of this study was to compare the accuracy and precision of three commonly used FEC methods and determine if differences existed among livestock species. In this study, we evaluated the modified-Wisconsin, 3-chamber (high-sensitivity) McMaster, and Mini-FLOTAC methods in cattle, sheep, horses, and llamas in three phases. In the first phase, we performed an egg-spiking study to assess the egg recovery rate and accuracy of the different FEC methods. In the second phase, we examined clinical samples from four different livestock species and completed multiple replicate FEC using each method. In the last phase, we assessed the cheesecloth straining step as a potential source of egg loss.In the egg-spiking study, the Mini-FLOTAC recovered 70.9% of the eggs, which was significantly higher than either the McMaster (P = 0.002) or Wisconsin (P = 0.002). In the clinical samples from ruminants, Mini-FLOTAC consistently yielded the highest EPG, revealing a significantly higher level of egg recovery (P < 0.0001). For horses and llamas, both McMaster and Mini-FLOTAC yielded significantly higher EPG than Wisconsin (P < 0.0001, P < 0.0001, P < 0.001, and P = 0.024). Mini-FLOTAC was the most accurate method and was the most precise test for both species of ruminants. The Wisconsin method was the most precise for horses and McMaster was more precise for llama samples. We compared the Wisconsin and Mini-FLOTAC methods using a modified technique where both methods were performed using either the Mini-FLOTAC sieve or cheesecloth. The differences in the estimated mean EPG on log scale between the Wisconsin and mini-FLOTAC methods when cheesecloth was used (P < 0.0001) and when cheesecloth was excluded (P < 0.0001) were significant, providing strong evidence that the straining step is an important source of error. The high accuracy and precision demonstrated in this study for the Mini-FLOTAC, suggest that this method can be recommended for routine use in all host species. The benefits of Mini-FLOTAC will be especially relevant when high accuracy is important, such as when performing FECRT.

Comparative transcriptomics gives insights into the evolution of parasitism in Strongyloides nematodes at the genus, subclade and species level

Strongyloides spp., gastrointestinal nematode parasites of humans and other animals, have genetically identical parasitic and free-living adult life cycle stages. This is an almost unique feature amongst nematodes and comparison of these two stages can provide insights into the genetic basis and evolution of Strongyloides nematode parasitism. Here, we present RNAseq data for S. venezuelensis, a parasite of rodents, and identify genes that are differentially expressed in parasitic and free-living life cycle stages. Comparison of these data with analogous RNAseq data for three other Strongyloides spp., has identified key protein-coding gene families with a putative role in parasitism including WAGO-like Argonautes (at the genus level) and speckle-type POZ-like coding genes (S. venezuelensis-S. papillosus phylogenetic subclade level). Diverse gene families are uniquely upregulated in the parasitic stage of all four Strongyloides species, including a distinct upregulation of genes encoding cytochrome P450 in S. venezuelensis, suggesting some diversification of the molecular tools used in the parasitic life cycle stage among individual species. Together, our results identify key gene families with a putative role in Strongyloides parasitism or features of the parasitic life cycle stage, and deepen our understanding of parasitism evolution among Strongyloides species.

Correction: The bacterial community associated with the sheep gastrointestinal nematode parasite Haemonchus contortus.

[This corrects the article DOI: 10.1371/journal.pone.0192164.].

Effects of herbal nutraceuticals and/or zinc against Haemonchus contortus in lambs experimentally infected

BackgroundThe gastrointestinal parasitic nematode Haemonchus contortus is a pathogenic organism resistant to several anthelmintics. This study assessed the efficacy of a medicinal herbal mixture (Herbmix) and organic zinc, as an essential trace element for the proper functioning of both unspecific and specific immune defensive mechanisms, against experimental infections with H. contortus in lambs. All lambs were infected orally with approximately 5000 third-stage larvae of a strain of H. contortus susceptible to anthelmintics (MHco1). Twenty-four female lambs 3–4 months of age were divided into four groups: unsupplemented animals (control), animals supplemented with Herbmix (Hmix), animals supplemented with organic zinc (Zn) and animals supplemented with Herbmix and organic zinc (Hmix+Zn). Eggs per gram (EPG) of faeces were quantified 20, 28, 35, 42, 49, 56, 62 and 70 d post-infection and mean abomasal worm counts were assessed 70 d post-infection. Samples of blood were collected from each animal 7, 35, 49 and 70 d post-infection.ResultsQuantitative analyses of the bioactive compounds in Herbmix identified three main groups: flavonoids (9964.7 μg/g), diterpenes (4886.1 μg/g) and phenolic acids (3549.2 μg/g). Egg counts in the lambs treated with Hmix, Zn and Hmix+Zn decreased after 49 d. The EPGs in the Zn and Hmix+Zn groups were significantly lower on day 56 (P < 0.05 and P < 0.01, respectively), and the EPGs and mean worm counts were significantly lower on day 70 in all supplemented groups (P < 0.05 and P < 0.01). Hemograms of complete red blood cells of each animal identified clinical signs of haemonchosis after day 35. Serum calprotectin concentrations and IgA levels were significantly affected by treatment. The treatment influenced serum malondialdehyde concentrations (P < 0.05) and sulfhydryl groups (P < 0.01) of antioxidant status. The mineral status was unaltered in all lambs.ConclusionA direct anthelmintic impact on the viability of nematodes was not fully demonstrated, but the treatments with herbal nutraceuticals and zinc likely indirectly contributed to the increase in the resistance of the lambs to nematode infection.

Field evaluation of Duddingtonia flagrans IAH 1297 for the reduction of worm burden in grazing animals: Tracer studies in sheep

The aim of these studies was to determine the reduction in pasture infectivity likely to be achieved by the supplementation of grazing sheep with BioWorma®, a product containing the chlamydospores of the nematophagous fungus Duddingtonia flagrans strain IAH 1297. Four placebo-controlled trials were conducted between 2009 and 2013 in sheep in different climatic regions of New South Wales and Queensland, Australia and across several seasons. The effectiveness of BioWorma was assessed by total worm counts in tracer sheep placed in paddocks grazed by parasitised sheep which were fed a daily supplement with and without BioWorma under group-feeding conditions. Further proof of concept was obtained by assessing the worm burdens and weight gains of the parasitised sheep, as well as the number of anthelmintic (“salvage”) treatments required when faecal egg counts exceeded a threshold level.Significant reductions ranging from 57 to 84% (P < 0.05) in worm burdens of the tracer sheep placed in the paddock grazed by BioWorma treated sheep were obtained in all four trials, compared to the Control group. In two of the studies the treatment effect was greater at the end of the trial, indicating that pasture infectivity in the Control paddocks had risen considerably. The main nematodes encountered were Haemonchus spp., Trichostrongylus spp., and Teladorsagia spp. (including multi-resistant strains) and significant reductions were demonstrated for each of these species.Given the results of the four trials it can be concluded that supplementation of pastured sheep with BioWorma was effective in reducing the numbers of parasitic nematode larvae ingested by tracer sheep. It is considered that these levels of reduced pasture larvae would result in productivity increases in grazing sheep and reduce the requirement for intervention with anthelmintic chemicals. Therefore, use of BioWorma will provide an alternative means for control of gastrointestinal nematode (GIN) parasites on pasture.

The bacterial community associated with the sheep gastrointestinal nematode parasite Haemonchus contortus.

Culture-independent methods were used to study the microbiota of adult worms, third-stage larvae and eggs, both in faeces and laid in vitro, of Haemonchus contortus, a nematode parasite of the abomasa of ruminants which is a major cause of production losses and ill-health. Bacteria were identified in eggs, the female reproductive tract and the gut of adult and third-stage larvae (L3). PCR amplification of 16S rRNA sequences, denaturing gradient gel electrophoresis (DGGE) and clone libraries were used to compare the composition of the microbial communities of the different life-cycle stages of the parasites, as well as parasites and their natural environments. The microbiomes of adult worms and L3 were different from those in the abomasum or faeces respectively. The H. contortus microbiota was mainly comprised of members of the phyla Proteobacteria, Firmicutes and Bacteroidetes. Bacteria were localised in the gut, inside eggs and within the uterus of adult female worms using the universal FISH Eub338 probe, which targets most bacteria, and were also seen in these tissues by light and transmission electron microscopy. Streptococcus/Lactococcus sp. were identified within the distal uterus with the probe Strc493. Sequences from the genera Weissella and Leuconostoc were found in all life-cycle stages, except eggs collected from faeces, in which most sequences belonged to Clostridium sp. Bacteria affiliated with Weissella/Leuconostoc were identified in both PCR-DGGE short sequences and clone libraries of nearly full length 16S rRNA bacterial sequences in all life-cycle stages and subsequently visualised in eggs by fluorescent in situ hybridisation (FISH) with group-specific probes. This strongly suggests they are vertically transmitted endosymbionts. As this study was carried out on a parasite strain which has been maintained in the laboratory, other field isolates will need to be examined to establish whether these bacteria are more widely dispersed and have potential as targets to control H. contortus infections.

Immune and other factors modulating host resistance against gastrointestinal nematode parasites in sheep

Infection of small ruminants with gastrointestinal nematode (GIN) parasites is a significant problem with crucial impact on meat and milk production. The strategy of administrating anthelminthic drugs has been implemented for many years and has resulted in the development of resistant strains of parasites. Meanwhile, consumers demand for free of drugs products have led to the adoption of alternative control methods, which involve the selective breeding of animals, which are resistant to parasitism. The development of immunity and therefore, resistance against gastrointestinal parasites is based on the activation of specific host genes. Gene analysis has revealed areas (QTLs), which affect resistance or susceptibility of sheep to gastrointestinal infestations between animals of different breeds and between individuals of the same breed. The role of cytokines and T helper cells has been enhanced as research, strongly, supports the connection of Th2 cells with resistance and Th1 cells with susceptibility against GIN. Latest data implicates T regulatory cells and a specific cell type, Th17, in immune response mechanisms. Specific adhesion molecules (integrins, lectins, cadherins) are produced in the gut lumen in sufficient amounts and appear to boost immunity and reduce clinical signs in sheep. Additionally, the immunoglobulins IgA and IgE have been positively correlated with increased resistance against GIN. In several cases of GIN, where an increased number of eosinophils and mast cells in the intestinal epithelium have been recorded, the animals had a reduced number of parasite eggs in their feces. The genes of the Major Histocompatibility Complex have been referred to as potential resistance or susceptibility markers. Other enzymes, like chitinases, enhance the resilience of animals and protect them effectively. Animal’s nutritional status is another determinant factor of immune capability against GIN in sheep, both systemic, as well as locally. Regarding the effect of reactive oxygen and nitrogen species, some researchers support their direct effect against GIN, resulting in a natural reduction of their number, while others claim the indirect action in the intestinal epithelium by reducing local immunity. Consequently, the detection of genes associated with resistance or susceptibility to gastrointestinal infestations is promising and in line with modern requirements.

Reduction rate of nematode egg counts and third-stage larvae development from sheep and goat faeces preserved at 4οC

Gastrointestinal nematode parasites cause major production losses to small ruminants. The most common way to diagnose or monitor the worm burdens in sheep and goats remains the quantitative parasitological examinations, i.e. the faecal egg counts. However, the reliability of the results of such methods depends greatly on the conditions and duration of the storage of the faecal samples prior to examination. The aim of this research was to evaluate the reduction rate and the maximum storage period, without significant losses, of nematode egg counts and third-stage larvae development from sheep and goat faeces preserved at 4οC. Towards this end, a pooled faecal sample was formed by collecting faeces from naturally infected sheep and goats (separately). Faecal egg counts and coprocultures were performed on fresh faeces and on preserved ones every week and up to 119 days post sampling. It was concluded that the preservation at 4oC, i.e. into a refrigerator, of fresh faeces from sheep and goats for parasitological examinations poses danger of misdiagnosis, if not performed in a period not exceeding 3 weeks of time. The rate of reduction of the faecal nematode egg counts starts to be significant lower than the ones performed with fresh samples, for both sheep and goats, after the third week of storage. The percentage of the gastrointestinal nematode larvae developing to the infective third–stage alters significantly for the Haemonchus genus, soon after the first week of storage (p&lt;0.05).

Little impact of over‐winter parasitism on a free‐ranging ungulate in the high Arctic

Abstract Macroparasites have a central place in wildlife ecology because they have the potential to regulate host populations through effects on reproduction and/or survival. However, there remains a paucity of studies that have demonstrated the regulatory role of these parasites in free‐ranging animals. Previous work on Svalbard reindeer demonstrated that the experimental removal of the parasitic gastrointestinal nematode Ostertagia gruehneri transmitted in summer, improved reindeer fecundity, and that the species was capable of mediating a density‐dependent reduction in fecundity. The main coexisting parasitic nematode in the system, Marshallagia marshalli, exhibits a contrasting life history with low abundances in summer and an increase during the winter. Here, we examine the impact of this over‐winter infection on fitness of female reindeer in the same population. Worm burdens were removed at the start of the winter in October using a novel delayed‐release anthelmintic bolus. Body mass and pregnancy rates were recorded for animals recaptured five (February) and seven (April) months later. The sub‐set of treated animals recaptured in February was treated again with anthelmintic to remove newly acquired nematodes. The experiment was replicated over six winters (2006/2007‐2011/2012) with a total of 343 recaptures, comprising 145 individual animals. We found little effect of anthelmintic treatment on reindeer body mass or pregnancy rates during the winter, suggesting that nematode infection during this time does not significantly affect fitness of Svalbard reindeer. Our studies are consistent with marked virulence nutritional trade‐offs in this system and highlights the need to integrate studies of parasite co‐infection, interspecific competition and community ecology to understand parasite impacts on hosts. A plain language summary is available for this article.

WITHDRAWN: The nematophagous fungus Duddingtonia flagrans reduces the gastrointestinal parasitic nematode larvae population in faeces of orally treated calves maintained under tropical conditions. Dose/Response assessment

Abstract This research assessed the dose/response to Duddingtonia flagrans chlamydospores (Df-C) administered to calves naturally infected with gastrointestinal nematodes (GINs), and its effect in reducing the infective larvae (L3) population in faeces in a farm in the Mexican tropics. Forty zebu calves, between 6 and 12 months of age, were randomly distributed into four groups of 10 calves. One control and three groups treated with different oral doses of Df-C based on their body weight (BW) were established as follows: group 1 (control); group 2, 0.250 × 106 Df-C per kg/BW; group 3, 0.5 × 106 Df-C per kg/BW and group 4, 1 × 106 Df-C per kg/BW. The fungal doses were administered daily for 10 days. Every group was confined to individual pens, and they received a nutritional regime based on Buffel grass, concentrated supplement and water ad libitum. Every third day, starting one week before treatments, faeces were taken from the rectum of each animal to determine the number of eggs per g of faeces (epg) through the McMaster technique. Four coprocultures of 20 g each from each individual faecal sample were prepared and incubated for 14 days. The efficacy of the treatments was based on the mean of the GIN L3 recovered from coprocultures of the different groups. Data were analysed using a completely randomized design through an ANOVA analysis, followed by a Duncan multiple range test. The efficacy of treatments was expressed as the larval reduction rate. High variation in the epg in the different groups along the experiment was recorded. The reduction in the GIN L3 population was observed from the 4 to 11 day post-treatment in the three assessed doses. Results in group 2 (lowest fungal dose), showed 88.5, 57.6, 55.9 and 30% (58% overall reductions) in the GIN L3 in the faeces of animals 4, 7, 9 and 11 days post-treatment, respectively. In group 3 (medium fungal dose), 95.8, 80.4, 63.4 and 52.7% GIN L3 reductions (73% overall reduction) were recorded, respectively. At the highest Df-C dose used (1 × 106 per kg/BW), the results were 88.9, 78.0, 59.3 and 67.3% (73.5% overall reduction), respectively (p

The role of condensed tannins in ruminant animal production: advances, limitations and future directions

ABSTRACT Tannins represent one of the most abundant polyphenolic compounds in plants. Tannins exist as a multitude of chemically unique entities in nature. The most commonly occurring tannins are typically divided into two major classes based on chemical structure: hydrolysable (HT) or condensed tannins (CT). Hydrolysable tannins are esters of gallic or ellagic acid linked to a polyol core, typically glucose. Condensed tannins or proanthocyanidins consist of flavan-3-ol subunits linked together to form oligomers and polymers. Both HT and CT are defined as astringent, medium-to-high-molecular weight polyphenolic compounds that characteristically bind and precipitate soluble proteins. The objective of this paper was to present recent advances in CT-ruminant interactions, the limitations associated with understanding and using CT in ruminant animal production, and future needs for research to further advance our knowledge of the role of CT in optimization of ruminant animal production. Condensed tannins pose some anti-nutritional problems to ruminants due to their astringent property that reduces feed intake and, consequently, animal performance. Ruminants can, however, tolerate CT by slowly adapting the ruminal microbes to the toxic effects of CT and by releasing CT-binding salivary proteins. The protein-binding ability of CT has some benefits to the ruminant due to complexes formed with essential amino acids, preventing their degradation in the rumen, but releasing them in the lower gut for absorption by the animal. Recent data have suggested increased N retention when CT is given to growing animals. There are potential benefits of using CT and HT for anthelmintic purposes due to their ability to inhibit egg hatching and larval motility of gastrointestinal nematode parasites, especially in small ruminants. Condensed tannins also bind to minerals (Al, Ca, Co, Cu, Fe, Mg, Mn, P, and Zn). Although studies with ruminants have been contradictory, it has been reported that because the CT-metal ion complex is stable over a wide pH range, CT may reduce the bioavailability of minerals. Methane mitigation by feeding CT might be the most impactful benefit for ruminant production. Many empirical equations have been developed to predict ruminal methane emissions, but very few have included CT. Future research should focus on the improvement of methodology to assess CT biological activity, interaction with other plant-specialized metabolites, and associated physiological and nutritional impacts on ruminants.

Anthelmintic resistance in gastrointestinal nematodes of goats in southern Mozambique

Small ruminant production is significantly constrained by gastrointestinal parasites once they cause serious production and economic losses for both small-scale and large-scale farmers in the developing world. The control of helminth parasites is most exclusively based on the use of anthelmintics for the economic production of ruminants. However, the resistance of nematodes to the commonly used groups of anthelmintics represents a threat to the production, particularly for small ruminants. The objective of this study was to assess the efficacy of albendazole, the most frequently used anthelmintic in Gaza and Maputo provinces in the southern region of Mozambique, in gastrointestinal nematodes of goats between November and December, 2016. Eleven goat farms in Gaza (n = 5) and Maputo (n = 6) were surveyed. The faecal egg count reduction test was used to assess the efficacy of the drug. The flocks were considered resistant when the reduction in eggs per gram of faeces was less than 95% and the lower limit of the confidence interval was less than 90%. Resistance to albendazole was detected in 60% (3/5) of the farms in Gaza province and 83.3% (5/6) of the farms in Maputo province. The percentage of faecal egg count reduction varied from 51 to 97% in Maputo and from 0 to 100% in Gaza in the farms surveyed. In pre-treatment coprocultures, Haemonchus spp., Oesophagostomum spp. and Trichostrongylus spp. were the predominant nematode species. Post-treatment larval cultures indicated that Haemonchus spp. and, to a lesser extent, Oesophagostomum spp. and Trichostrongylus spp., were resistant to albendazole. This study provided further evidence that anthelmintic resistance of gastrointestinal nematode parasites in goats is currently a problem of great significance in this region of the country and that appropriate measures must be taken to reverse the situation. Key words: Albendazole, efficacy, gastrointestinal parasites, small ruminants, Mozambique.

Biological control on gastrointestinal nematodes in cattle with association of nematophagous fungi

ABSTRACTThis study aimed to evaluate the efficacy of the association of the nematophagous fungi (Duddingtonia flagrans-AC001); (Pochonia chlamydosporia-VC4) and (Arthrobotrys robusta-I31) in a pelletised formulation of a sodium alginate matrix. The viability and activity of pellet germination and fungal activity (after encapsulation) were evaluated using in vitro and in vivo tests. Next, 12 heads of cattle, Dutch mestizo x zebu, with an average age of 12 months were dewormed with an anthelmintic. Next, 20 days after treatment with the anthelmintic, the animals were randomly divided into two groups of six animals each, and placed in two paddocks with 7.0 ha each of Brachiaria decumbens with historical grazing by animals naturally infected by gastrointestinal nematode parasites. At first, each animal was treated with 2 g of pellets per 10 kg of animal, containing the associated fungi (AC001 + VC4 + I31) administered twice a week in conjunction with commercial feed. Each animal in the control group received 2 g of pellets without mycelia added to the feed. The percentage reduction of infective larvae in the in vitro test was 94% (p < .01). In the in vivo test, the treated animals with fungal association had lower egg counts per gram of faeces (p < .01) compared to the control group animals – a reduction of 91.8%. The reduction in the number of infective larvae recovered from the pasture was 27.5% at a distance of 0–20 cm from the stool bulk, and 26.7% at a distance of 20–40 cm. This association (AC001 + VC4 + I31) of nematophagous fungi was effective in nematode control.