Condensed tannins - part of an integrated control strategy against
gastro-intestinal nematodes in ruminants
Veronika
Maurer, Felix
Heckendorn
The project compiles basics on tanniferous forage plants in Switzerland
and their use to control GI Nematodes in ruminants.
Keywords: Gastro-Intestinal Nematodes (GIN), Condensed Tannins
(CT), Ruminants
Gastro-intestinal nematodes (GIN)
In organic dairy farms, infection of grazing cattle and also of
small ruminants with gastro-intestinal nematodes (GIN) is an important
factor influencing animal health status.
Clinical and subclinical infection is therefore also considered
to be of substantial economic importance.
The livestock owner is confronted with problems to (i) reduce the
infection pressure to an acceptable level and to (ii) resign to
the wide use of pharmaceutical products as claimed by the swiss
ordinance on organic farming.
Up to present, complementary treatment approaches like homeopathy
or phytotherapy did not lead to a satisfactory control of internal
parasites, and alternatives like biological control measures are
not available yet. Therefore, in organic farming, the control of
internal parasites of ruminants still predominantly relies on the
use of anthelminthics.
This fact is further pronounced by the fact that many of the economically
important parasites show resistance against intensively used anthelmintics.
As a consequence, the use of anthelmintic drugs is presently intensified
in organic farming. This situation is incompatible with the philosophy
of organic farming.
Scientific approaches for an alternative control of ruminant GIN
Scientific approaches for an alternative, non-conventional control
of ruminant GIN are the following:
- Grazing management, as a stategy to reduce pasture parasite
density (dilution).
- Biological control using nematophagous fungi of which the spores
are fed to the host.
- The use of tanniferous plants.
Studies using approaches 1 & 2 have shown a reduction of endoparasites.
However, for small ruminants and first season grazing cattle further
measures are needed in order to effectively control GIN.
Anthelmintic properties of plants containing condensed tannins
Several studies with plants containing condensed tannins (CT) (mainly
from New Zealand and Scandinavia) have shown anthelmintic properties
and the observed effects have been attributed to their elevated
CT content. Effects have been found on adult parasites in vivo and
also on larval stages in vitro.
The use of tanniferous plants as forage crops
The use of tanniferous plants as forage crops has the potential
to be included in an integrated control strategy against GIN. CT
protect dietary nitrogen from rumen degradation by microorganisms
and ameliorate protein supply in ruminants with positive effects
on growth, wool production and milk yields. Furthermore, CT's prevent
rumen bloat in grazing ruminants.
In order to implement tanniferous plants into a control strategy
against GIN, they have to be adopted to local conditions. Most importantly,
climatic conditions and also common crop production systems have
to be taken into account. Considering the mentioned needs, worldwide
and particularly in Switzerland, no adequate strategy is available.
Kontakt
Felix Heckendorn, FiBL
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