Exotic Acacia species

Abstract

DISTRIBUTION: Originally from Australia. Now aggressive invader species to be found all over the country.

BOTANICAL DESCRIPTION: Medium to large trees. Yellow pom-pom flowers. Differences between positions of the glands on the rachis of each respective leaf to be noted.

TOXIC PRINCIPLE: Tannic acid, which denatures and precipitates protein – thus rendering protein indigestible.

SYNDROMES: Tannic acid, Primary necropathy.

SYSTEMS AFFECTED: Urogenital system.

CLINICAL SIGNS: • At high doses tannic acid results in initial constipation (astringent action) followed by diarrhoea. • Absorption and metabolism result in liver and kidney damage. • In ruminants long term intake at lower levels causes severe interference with protein availability, and, therefore, a deficiency. • This is particularly a problem in confined browsing game that is forced to graze the trees or shrubs. • As a deterrent to herbivores, trees have the ability to rapidly (3-4min) mobilize and translocate tannins temporarily to their leaves on stimulus of physical damage. • This makes them unpalatable and they can even communicate the fact that they are being damaged to other trees downwind through liberation of the gas ethylene. • The problem is compounded by the fact that over utilization of such trees occurs during periods of protein deficiency and such browsers may die from malnutrition amidst an apparent abundant supply of food.