Tannin poisoning of game and livestock is a risk against which the game farmer should take precautions. Some plants produce tannins as a means to defend themselves and when grazed upon, the tannin build-up can be sufficient to poison the animals. Tannin levels are lower in the warmest part of the day whilst increasing during the cooler evenings. Young plant leaves contain more tannin than mature leaves. In times of drought or overgrazing, animals are forced to browse on high tannin containing plants. It is thus important to take steps to reduce the risk of tannin poisoning on game and mixed farming enterprises. Poisoning of animals differs according to the animals, as tannin affects various animals differently.
This type of tannin causes the inhibition of enzymes and protein precipitation. The result is a deficiency in certain nutrients. Such poisoning causes malabsorption of protein, leading to leanness of the animal. The high concentration found in foliage is usually not a problem, since such concentrations have a sharp taste that most animals do not like. However, if animals are forced to forage on plants high in condensed tannins (drought, small camps etc.), it could negatively affect the wellbeing of the animals.
Another form of poisoning occurs as the result of the decarboxylation of hydrolysable tannins, which gives off pyrogallol. Effects can range from liver necrosis to haemorrhagic gastroenteritis and kidney tubular necrosis. This type of poisoning causes acute deaths. The binding of tannins in saliva differs from one animal species to another i.e. giraffe, eland, and some other species do not have rumen microbes that can help with the digestion of the tannins.
How Animals Cope
Many browsing animals are selective and thus choose plants that contain less than 5% tannins. The browsers move from one tree to another and thereby reduce the risk of suffering from tannin poisoning. Browsers are able to secrete protein-rich saliva that binds with the tannins. However, they need to move from one area to another in order to prevent being poisoned. By fencing off animals, farmers leave the animals sometimes no choice but to browse on plants high in tannins. The solution is to reduce the stock rate per hectare and to supply Browse Plus®, a polyethylene glycol based product, through the animals’ drinking water. The supplement ensures the binding of the tannins and thereby helps to prevent tannin poisoning.
Where to Buy
Browse Plus® is a Virbac product and available from most agribusinesses. It is well suited for supplementing the nutritional needs of game as a digestive modifier and as an aid in the prevention of tannin poisoning. Call us for more information regarding the product to ensure the optimal health of your farm and game livestock, especially during the dry months when forage is insufficient to meet the nutritional requirements of the animals.