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Tannin-rich pastures and browse for control of parasites in goats

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Internal parasites are a challenge for goat producers. An integrated approach to management is recommended. One tool available to goat producers may be incorporating plants with anthelmintic properties (via high levels of tannins) which help lower worm burdens. Such plants can include grasses (grazed or fed via hay/silage) or browse plants.

These species not only have high tannins levels, but they offer a high plane of nutrition which aids in supporting their resilience to withstand internal parasites. High levels of tannins are often unpalatable to livestock; however, goats are an exception. Grass species vary in tannin concentrations and thus their anthelmintic capabilities. Success will depend on enough of certain species being consumed. The concentration of active tannins can be affected by climate, soil type and the processing of hay or silage.

The most promising forage species showing some anthelmintic properties are:

  • temperate legumes such as sainfoin (Onobrychis viciifolia) in Europe, and sericea lespedeza (Lespedeza cuneata) in South Africa and USA
  • tropical legumes such as Leucaena leucocephala in Australia, and Arachis pintoi, Gliricidia sepium and Cratylia argentea in Mexico
  • heather species, Erica spp. and Caluna sp. (Ericeacae) in Spain
  • chicory (Cichorium intybus) in Australia, New Zealand and the USA
  • sulla (Hedysarum coronarium) (Asteraceae) in Australia and New Zealand

To incorporate these forage plants into a sward, you could oversow existing pastures, grow as a monoculture for a worm control paddock or grow a forage bank and offer to goats as hay and silage.

Additional benefits from tannins include protection from bloat and helping protect protein being degraded in the rumen. However, take caution as high levels of tannins have been associated with lower levels of digestibility and palatability.

Browse simply means leaves, twigs or shrubs. Goats actually prefer browse to grasses and will consume up to 80% of their diet as browse if available. Browse is generally higher in crude protein and phosphorus during the plant’s growing period. However, there are some inhibitors which may limit this.

Browse species play an interesting role protecting goats from internal parasites. Firstly, through providing higher concentrations of tannins in the diet and secondly by reducing the exposure of goats to infective larvae. The latter occurs as browse plants allow goats to graze more than 15 cm above the ground. As larvae do not venture this far up a sward, they can therefore not be ingested by goats. Basically, they separate the goat’s mouth from contact with infective larvae.

Though this provides an excellent opportunity to avoid parasites, excessive tannins may also increase a goat’s requirement for sulphur, which is problematic for hair producing goats and goats can be rough on browse species leading to ringbarking and broken branches. Careful management is required to preserve these important species.