A technique for the quantification of Duddingtonia flagrans chlamydospores in sheep faeces

Nematode predatory ability of the fungus Duddingtonia flagrans affected by in vitro sequential exposure to ovine gastrointestinal tract

Duddingtonia flagrans is a nematophagous fungus employed as a biocontrol agent of gastrointestinal nematodes in ruminants. After oral ingestion and passage through the digestive tract of animals, this microorganism captures the nematodes in the feces. The drastic conditions of ruminant digestive tract could affect fungi chlamydospores and therefore biocontrol activity. The aim of this study was to evaluate in vitro the effect of four ruminant digestive segments on the concentration and nematode predatory ability of a Colombian native strain of D. flagrans. The sequential four-step methodology proposed evaluated conditions of the oral cavity, rumen, abomasum, and small intestine such as pH (2, 6, 8), enzymes (pepsin, pancreatin), temperature (39 °C), and anaerobiosis comparing short (7 h) and long (51 h) exposure times. The results showed that the nematode predatory ability of the fungi is affected by sequential exposure to gastrointestinal segments and this effect depends on the exposure time to those conditions. After short exposure (7 h) through the four ruminant digestive segments, the fungi had a nematode predatory ability of 62%, in contrast, after long exposure (51 h) the nematode predatory ability was lost (0%). Moreover, the number of broken chlamydospores was higher in the long-exposure assay.

Assessment on bioactive role of Moringa oleifera leaves as anthelmintic agent and improved growth performance in goats

The aim of this study was to evaluate the bioactive effect of Moringa oleifera leaves hydroalcoholic extract as a dietary feed additive on helminths load and growth performances of goats. Initially, the availability of bioactive compounds in M. oleifera hydroalcoholic extract was analysed using gas chromatography-mass spectrometry (GC-MS), which showed the presence of heneicosane (35.69%), 1,2-benzenedicarboxylic acid (22.89%), heptacosane (18.26%), pentatriacontane (4.77%), and hexadecanoic acid ethyl ester (3%) as predominant compounds in the leaves extract. The anthelmintic effect of M. oleifera extract (0 and 60 mL of extract animal^-1) was evaluated against disparate nematodes using standard methodology. M. oleifera leaves extract exhibited significant (P = 0.002) anthelmintic activities against Trichuris sp. and Ostertagia sp. with reduced counts of eggs. A completely randomized experiment of 3 treatments comprised of 10 goats in each treatment was designed for the growth performance study. Treatments used in the present experiment were as follows: treatment 1 (T1), 0 mL of extract animal^-1; treatment 2 (T2), 30 mL of extract animal^-1; and treatment 3 (T3), 60 mL of extract animal^-1. Growth performance parameters (body weight, daily weight gain, and feed intake values) of goats fed varied concentrations of M. oleifera extract were estimated as per standard protocols. The T2 and T3 groups' goats offered significant (P < 0.05) increment in body weight. Daily weight gain of the T2 and T3 groups' goats was also increased. Group T3 exhibited maximum feed intake value of 588, 678, 652, and 678 g d^-1 at 0, 30, 45, and 60 days, respectively. Feed conversion efficiency was increased for T2 and T3 groups' goats versus T1. Findings of this study concluded that M. oleifera hydroalcoholic extract can be used not only as an effective anthelmintic agent against disparate nematodes but also as a prominent feed additive to improve growth performances of goats.

In vitro evaluation of physicochemical variables on the nematophagous fungus Duddingtonia flagrans

Duddingtonia flagrans is a biological alternative to the use of anthelmintic drugs in ruminants. This fungus must be ingested by the animal, pass through the cavities of the digestive tract and reach the feces where it develops traps that capture the nematodes. The severe conditions encountered in this process negatively affect the fungus, which is reflected in the low recovery rates compared to the amount administered. The aim of this study was to evaluate independently the in vitro effect of typical physical and chemical conditions of the gastrointestinal cavities of ruminants on the concentration, viability, and the in vitro nematode predatory ability of the chlamydospores of D. flagrans. The factors evaluated individually were pH (2, 6, and 8), temperature (28 ± 2°C and 39 ± 2°C), exposure to artificial saliva, and milling. The results showed that the concentration and viability of D. flagrans were not affected by the action of pH, temperature, milling, or exposure to artificial saliva. Regarding the in vitro nematode predatory ability, a reduction was observed after the milling process and the exposure for 24 h at different pH.

In vitro predatory activity of nematophagous fungi isolated from water buffalo feces and from soil in the Mexican southeastern

Nematophagous fungi from the feces of water buffalo and soil from southeastern Mexico were isolated, and their in vitro predatory activity against Haemonchus contortus infective larvae (L3) (HcL3) was assessed. The fungi were isolated by sprinkling soil or feces on water agar plates. Six series of 10 Petri dishes containing a 7-day-old culture of each fungus and a series without fungi as the control were prepared. Five hundred HcL3 were added to each plate. The plates were incubated at room temperature. The average of recovered HcL3 was considered to estimate the larval reduction rate. Four nematophagous fungi isolates corresponding to Arthrobotrys oligospora, var microspora (strains 4-276, 269 and 50-80) and one identified as A. oligospora,var. oligospora (isolates 48-80) were obtained from water buffalo feces. From the soil, five isolates were isolated; three corresponded to A. musiformis (Bajío, Yumca and Macuspana isolates), and two isolates were identified as A. oligospora (Comalcalco and Jalapa de Méndez isolates). The predatory activity of isolates from water buffalo feces ranged between 85.9 and 100%. Meanwhile, the fungi from the soil ranged between 55.5 and 100% (p≤0.05). The nematophagous fungi obtained could have important implications in the control of parasites of importance in the livestock industry.

Implementation of Biological Control to the Integrated Control of Strongyle Infection among Wild Captive Equids in a Zoological Park

The integrated control of strongyles was assayed for a period of three years in wild equids (zebras, European donkeys, and African wild asses) captive in a zoo and infected by strongyles. During three years control of parasites consisted of deworming with ivermectin + praziquantel; equids also received every two days commercial nutritional pellets containing a blend of 10⁴ - 10⁵ spores of the fungi Mucor circinelloides + Duddingtonia flagrans per kg meal. Coprological analyses were done monthly to establish the counts of eggs of strongyles per gram of feces (EPG). The reductions in the fecal egg counts (FECR) and in the positive horses (PHR) were calculated fifteen days after deworming; the egg reappearance period (ERP) and the time elapsed from the previous deworming (TPD) were also recorded. Four anthelmintic treatments were administered during the assay, three times throughout the first 2 yrs, and another treatment during the last one. FECR values of 96-100% and 75-100% for the PHR were recorded. The ERP oscillated between eight and twenty-eight weeks, and the TPD ranged from four to eighteen months, increasing to the end of the trial. No side effects were observed in any of the equids. It is concluded that integrated control of strongyles among equids captive in a zoo can be developed by anthelmintic deworming together with the administration of pellets manufactured with spores of parasiticide fungi every two days.

Anthelmintic effects of Salix babylonica L. and Leucaena leucocephala Lam. extracts in growing lambs

Twenty Katahdin × Pelibuey crossbreed male lambs, 3 to 4 months of age and 24 ± 0.3 kg of body weight, were used to study the anthelmintic effects of administering extracts of Salix babylonica L. (SB) and Leucaena leucocephala Lam. (LL). Lambs had not been treated with anthelmintics previously and were randomly allocated into four groups of five lambs each in a completely randomized design. Treatments were as follows: control (lambs fed on total mixed ration without extracts), SB (as control plus S. babylonica L. extract at 30 ml/day), LL (as control plus L. leucocephala Lam. extract at 30 ml/day), and SBLL (as control plus 30 ml/day of S. babylonica L. and L. leucocephala Lam. extracts in a 1:1 (v/v) mixture) for 63 days. Extracts were orally administered before the 8:00 a.m. feeding to each lamb. Rectal fecal samples were collected from each lamb at day 22 (P1), day 43 (P2), and day 63 (P3) of the experiment. Adult worm and egg counts were determined in each fecal sample immediately after collection. Plant secondary metabolites of total phenolics, saponins, and the aqueous fraction were 50 % lower in the SB versus LL extracts. Overall, the oral administration of extracts has improved the egg and worm count reductions in lamb feces by 54, 47, and 40 % for LL, SB, and SBLL, respectively, versus the control lambs. Reductions of worm egg counts in lamb feces were higher (P < 0.05) in P2 and P3 versus P1. Extracts of SB and LL or possibly isolated bioactive compounds could be a promising alternative to conventional anthelmintics to treat gastrointestinal parasites of small ruminants. Such treatments could be used in control strategies against gastrointestinal nematodes in organic and conventional production systems.

Analysis of the accuracy and precision of the McMaster method in detection of the eggs of Toxocara and Trichuris species (Nematoda) in dog faeces

The aim of this study was to determine the accuracy and precision of McMaster method with Raynaud's modification in the detection of the eggs of the nematodes Toxocara canis (Werner, 1782) and Trichuris ovis (Abildgaard, 1795) in faeces of dogs. Four variants of McMaster method were used for counting: in one grid, two grids, the whole McMaster chamber and flotation in the tube. One hundred sixty samples were prepared from dog faeces (20 repetitions for each egg quantity) containing 15, 25, 50, 100, 150, 200, 250 and 300 eggs of T. canis and T. ovis in 1 g of faeces. To compare the influence of kind of faeces on the results, samples of dog faeces were enriched at the same levels with the eggs of another nematode, Ascaris suum Goeze, 1782. In addition, 160 samples of pig faeces were prepared and enriched only with A. suum eggs in the same way. The highest limit of detection (the lowest level of eggs that were detected in at least 50% of repetitions) in all McMaster chamber variants were obtained for T. canis eggs (25-250 eggs/g faeces). In the variant with flotation in the tube, the highest limit of detection was obtained for T. ovis eggs (100 eggs/g). The best results of the limit of detection, sensitivity and the lowest coefficients of variation were obtained with the use of the whole McMaster chamber variant. There was no significant impact of properties of faeces on the obtained results. Multiplication factors for the whole chamber were calculated on the basis of the transformed equation of the regression line, illustrating the relationship between the number of detected eggs and that of the eggs added to the'sample. Multiplication factors calculated for T. canis and T. ovis eggs were higher than those expected using McMaster method with Raynaud modification.

Administration of the nematophagous fungus Duddingtonia flagrans to goats: an evaluation of the impact of this fungus on the degradation of faeces and on free-living soil nematodes

The environmental impact of Duddingtonia flagrans, a potential biological control agent for nematode parasites, was tested in a 2-year-plot study using goat faeces. The trial assessed the impact of fungal presence on the disintegration of faeces and on non-target, free-living soil nematode populations. Three groups of goats experimentally infected by Trichostrongylus colubriformis received three different doses of D. flagrans chlamydospores (0 chlamydospores/kg body weight (BW), 0.5 × 106 chlamydospores/kg BW or 5 × 106 chlamydospores/kg BW). One hundred grams of faeces containing T. colubriformis eggs and D. flagrans chlamydospores at three different concentrations were deposited on pasture plots on four different occasions: May 2003, September 2003, June 2004 and September 2004. Faeces were weighed 2, 4, 6, 8, 10, 12, 14, 16, 18 and 20 weeks after deposit and immediately afterwards replaced to their initial positions. In addition, soil samples were taken just below faecal deposits to evaluate the impact of fungal presence on non-target free-living nematodes. Results showed that there was no treatment effect on the pellet degradation rate. Analysis of soil nematode fauna failed to demonstrate any effect of the dose rate of 0.5 × 106 chlamydospores/kg BW, while a reduction of the number of free-living nematodes was seen for the maximal chlamydospore concentration at autumn sets.

Digestibility of Duddingtonia flagrans chlamydospores in ruminants: in vitro and in vivo studies

BACKGROUND

The use of Duddingtonia flagrans as a tool for the biological control of gastrointestinal nematodes (GIN) is a promising alternative to anthelmintics. The chlamydospores of D. flagrans are orally dosed and their thick cell wall gives them the capacity to resist digestion and pass through the gastrointestinal tract (GIT). Chlamydospores reaching the faeces are able to germinate and trap nematode larvae. The efficacy of this control method is based on reducing the numbers of infective larvae leaving the faeces. Techniques have recently been developed for quantifying the numbers of chlamydospores in faeces. As the number of non-digested spores could be relevant in the design and optimization of dosing programmes for the control of GIN infective larvae, the aim of the present study was to estimate the loss of D. flagrans chlamydospores during their passage through the ruminant gastrointestinal tract using in vitro and in vivo techniques.

RESULTS

After in vitro rumen digestion, chlamydospore recovery was not different from the quantity originally incubated (undigested spores) (P > 0.05). In vitro rumen+abomasum digestion caused nearly 36% loss of the chlamydospores originally incubated (P < 0.05). Germination of chlamydospores classified as viable was 24.3%. Chlamydospores classified as non-viable did not germinate. Rumen digestion resulted in more spore germination (R1 = 35.7% and R2 = 53.3%) compared to no digestion (time 0 h = 8.7%). Subsequent abomasal digestion reduced germination (R1+A = 25%) or stopped it (R2+A = 0%). In vivo apparent chlamydospore digestibility in sheep showed a loss of 89.7% of the chlamydospores (P < 0.05).

CONCLUSIONS

The loss of chlamydospores was evident under in vitro and in vivo conditions. Negligible amounts of spores were lost during the in vitro rumen digestion. However, in vitro rumen+abomasum digestion resulted in a chlamydospore loss of approximately 36%. In vivo passage through the sheep GIT resulted in a total loss of 89.7% of the orally administered spores.