All of the commercially farmed ruminant species i.e. cattle, sheep, deer and goats are susceptible to nitrate toxicity. Nitrate is taken up by plants from the soil and is converted into protein for plant growth. Under certain growing conditions these levels can build up enough to be dangerous to grazing animals.
These conditions include drought followed by rain, cloudy weather with active growth and the addition of nitrogenous fertilizer. Plants that have been associated with nitrate problems include rape, choumoellier, turnips, ryegrass (particularly new grass and short rotation Italian types), wheat, barley, sorghum and oats.
When animals graze plants high in nitrate, nitrite (this is not a chemistry lesson but nitrite is simply nitrate with one oxygen removed) builds up and binds to the haemoglobin in the blood. This interferes with the blood's ability to carry oxygen and turns the blood a brownish colour. Symptoms range from sudden death through to increased breathing rate, gasping, increased heart rate, incoordination and salivation.
If you are concerned that this profile fits your animals, remove them from the offending material immediately and call Totally Vets. This is one toxicity for which we have a specific antidote: if given early, methylene blue can minimise losses.
However, prevention is better than cure! There are several management strategies that can be employed to reduce the risk of grazing potentially dangerous crops or pastures. These are essentially concerned with reducing the time grazing these paddocks, managing the amount of gut-fill prior to being introduced onto the paddock or new break, and careful observation.
If you have paddocks that you are concerned about, bring in a supermarket bag of the plant material. Totally Vets can analyse the nitrate levels and give you advice on how safe this pasture is to use.
