Some soil moisture is necessary for absorption and accumulation of the nitrates. Nitrate Toxicity in the Animal Like plants, ruminant animals also use the nitrogen in nitrates to make protein. Conversion is made by bacteria in the rumen. Nitrite, one of the intermediate products in this conversion, is the cause of nitrate poisoning. When this happens, nitrite accumulates and is absorbed into the bloodstream.
Cattle are much more likely to be affected than are sheep or horses.
The toxic level depends both on how much and how fast nitrate was consumed. In the case of forage, toxicity generally occurs when cattle consume large amounts of forage containing 1.76 percent or more nitrate ion on a dry matter basis. Even forage with lower levels of nitrate may adversely affect reproduction or become toxic if animals are nutritionally stressed or ill and they suddenly consume large quantities of such forage. The recommended uses for forages containing various levels of nitrate are listed in Table 2. A high level of nitrate or nitrate in drinking water may make it necessary to further reduce intake of nitrate containing forage.