The once a day feeding program results in higher total methemoglobin levels than twice a day feeding. With once a day feeding, a larger quantity of feed is consumed at once and a greater amount of nitrate is released from the feed in a short period of time. Animals are often found in a lying position after a short struggle. In most cases of acute poisoning, animals are found dead before any signs of toxicity are observed. Nitrate is the form of nitrogen that the plant roots take up from the soil, and is transported to the leaves.
Excess nitrates accumulate in plants when they are stressed.
Drought or hot dry winds put forage under water stress often resulting in nitrate accumulation. Damage caused by hail or frost impairs photosynthesis resulting in excess nitrates. Cool cloudy weather can also cause the problem. When any of these conditions occur within a few days of harvest or grazing, the potential for nitrate poisoning exists. If the stress is removed and the plants recover, nitrate levels should return to normal within several days.