Dear Daktari, Thanks for your informative articles. I am a dairy farmer practising free ranging in Eldoret. Recently, I noticed bloody urine in two of my cows and I immediately called a vet. He examined the cows and insisted on walking round my farm. He told me my pasture was infiltrated with poisonous plants and the bloody urine was most likely attributed to the bracken ferns. I think it would be beneficial to educate my fellow farmers on this issue. [Sam Kipkemboi, Eldoret]
Thank you Mr Kipkemboi for your feedback. Yes, there are a number of plants that are poisonous to livestock when eaten. While some appear appetising to livestock in dry seasons, most sprout when it is raining alongside edible pastures and are consumed accidentally by cattle. In dry periods livestock are pushed into eating poisonous plants due to starvation. Animals sometimes feed on poisonous plants in search of variety.
The resultant health risks depend on the quantity of poisonous plants ingested, the period over which it has been exposed to the poisonous plant, the animal species and the type of plant or the part that has been consumed. The health status of the animal will also determine the outcome of poisoning. Here are some poisonous plants to look out for.
Lantana is a plant common on many hedges and in bushes. Goats love feeding on its leaves and seeds but when consumed in large quantities it causes wounds or sores on the skin of animals when they are exposed to sunlight. The resultant condition is called photosensitivity. In severe conditions it can cause death in goats.
Bracken Fern is a common weed in pastures; especially natural pastures that are not taken good care of. It is a common poisonous plant and prolonged ingestion causes development of tumours in the bladder and this is what causes bloody urine. Other signs include weakness, pale mucus membranes due to anaemia, rapid loss of weight.
Cotton Seed is sometimes used in animal feeds but it contains a poisonous chemical called gossypol which is poisonous to pigs and young ruminants. When preparing cotton seed cake use heat treatment to destroy the gossypol. Cotton seed poisoning appears after prolonged ingestion and clinical signs include loss of appetite, weakness and death.
Datura/nightshade is a common weed in farms and all parts of this weed are poisonous. While most livestock avoid datura, it can be accidentally or intentionally (maliciously) find itself in animal feeds. It can be harvested through hay or silage. It affects cattle, goats, horses and poultry. Among its clinical signs are restlessness, rapid heart rate, diarrhoea, retained urine and death are observed in datura poisoning.
How to protect livestock from poisonous plants
First, identify the poisonous plants in your farm or neighbourhood. Next, establish the conditions under which it is likely to be ingested for example accidentally or intentionally and the likely season. This should be followed by strategic grazing to limit exposure. Do not move hungry or new animals into fields with poisonous plants. Proper nutrition which ensures animals have access to adequate water and mineral supplementation helps limit intentional ingestion of poisonous plants by animals. Chemically or manually remove poisonous plants from the farm. Sensitising the farm hands about these plants also helps.
Finally, call in your veterinary doctor in case you suspect plant poisoning in your animals.