Control of gastrointestinal worms of small ruminants by nematophagous fungus Duddingtonia flagrans
Grazing of sheep and goats is compromised by gastrointestinal strongyles. Many worms have developed Anthelmintic Resistance. Promoting the natural predation of worm stages on pasture could possibly reduce the infection pressure for the livestock.
Clinical and subclinical endoparasitism threatens the small ruminant husbandry. The economical losses due to the reduced gain of bodyweight, milk yield and wool production are described. Facing the progressive extension of resistance against deworming drugs, other ways to control parasites are to consider. In organic farming alternatives to chemical treatment are desirable. One way may be the method of biological control of nematodes by promotion of natural enemies. Since the late thirties of the last century, the principle is known. Some years ago this approach has been resumed for parasitic nematodes in livestock. As a suitable candidate, the nematophagous fungus Duddingtonia flagrans has been discovered, because its spores get not digested and survive the gastrointestinal passage through the animal with good germinating capacity. By daily supplementation of a certain amount of spores, they can be excreted at each defecation. In the dungpat the parasite larvae are reduced by fungal prey as eggs and spores are developing at the same time. Thus, the infection pressure is reduced in the pasture. After very good results in the nineties in vitro and in field studies on young cattle, the company Chr. Hansen from Denmark developed a patented process for the preparation of the spore material. About the use of Duddingtonia flagrans in small ruminants little research had been conducted so far. It should be clarified whether the mentioned method could be recommended for goat and sheep farming.
By turnout of the year 2002, twenty first- and secondseason grazing, naturally infected, female goats (German Improved Goat) and twenty similar sheep (East Friesian sheep, var. black.) were fed additionally for 3 months daily with 0.5 million spores of D. flagrans per kg body weight, mixed in a small concentrate ration (100 g/animal/day). Chr. Hansen Ltd., Horsholm, Denmark provided the spore material. It was fed in long troughs, so each animal had a feeding place. The two identical control groups received the concentrate ration without the spore material. All four groups grazed their own pasture (1.4 ha / group).
Every fortnight until stabling in October for each animal the body weight and the number of eggs per gram of feces (fecal egg count) were determined. On four dates, blood samples were taken for determination of serum pepsinogen. In addition, every 14 days the larvae from fecal cultures and pasture grass samples (2 per pasture) were counted. In the middle and at the end of the grazing season 2 tracer animals, without former contact to worms, were added to each group. After three weeks of grazing followed by three weeks indoors these animals were slaughtered and necropsied to determine their worm burden.
In 2003, a trial was performed at 45 milking goats to influence the excretion of eggs and optionally save a deworming treatment by feeding the nematophagous fungus Duddingtonia flagrans. We fed daily 1.2 million spores/kg body weight for 6 weeks, and then further 6 weeks long 0.25 million spores/kg body weight.
Fecal Egg Count done by McMasterMethod with a sensitivity of 33 eggs per gram of fresh feces.
Body weight: Electronic livestock scale, ± 0.1 kg
Fecal cultures (3-5 animals pooled) for the quantitative determination of larvae and their differentiation
Larvae determination of pasture grass samples by method of Sievers Prekehr
Serumpepsinogen: tyrosine determined photometrically. Tracer: After rinsing, investigation of 10% aliquot by a sieve with mesh size 100 µm
Statistics: Excel (C) Microsoft
In the year 2002, the goats of the control group showed after three months only at two times significantly higher mean fecal egg counts than the fungus fed group (p <0.05). In the sheep there were no significant differences. In control groups diseased individuals had to be treated more often with anthelmintics, as in the experimental groups (not significant). Maximum reduction of numbers of larvae in fecal cultures were 81.3% for sheep and 67.9% for goats (not significant). Species differentiation in fecal cultures showed that all expectable worm species were present and the feeding of D.flagrans - spores had no visible effect on the species distribution.
At the end of the grazing season the mean body weight gain of the fungus fed goats was higher than in the control group (1.7 kg, not significant) and as well in sheep (0.7 kg, not significant). Only the subgroup of firstseason grazing goats reached significant body weight differences (p <0.05). No significant differences were found at the pasture larvae. The evaluation of the results of the 8 traceranimals showed that the first group (turnout to pasture 1st of August) had greater number of pathogenic worms (Haemonchus contortus, Teladorsagia circumcincta) than the tracers with the late turnout (25.September). This was also clinically observed. Differences between experimental and control group tracers could not be determined because of the small number (n = 2).
The serum pepsinogen value, as an expression of abomasal damage done by worms, raised up to the end of August. The difference within the goatgroups was at this time significant.
The weather conditions (extreme high rainfall) may have influenced the in total disappointing results and have thus shown how sensitive this method seems to be against such parameters.
In 2003, the feeding of the spores could not prevent a sharp rise in the excretion of eggs during the grazing period and the contamination of the pasture was high. A deworming treatment in summer (during lactation!) could not be avoided.
Due to similar disappointing results in sheep determined by other research groups, and due to the fact that an EU proposal of the company for the recognition of D.flagrans spores as a permitted feed-additive was refused, Chr.Hansen Ltd. has stopped production of spores. No further experiments are planned.
9.2001 - 9.2004
Project status: finished