Pearl millet (Pennisetum glaucum
) is an annual, tall growing, warm-season grass which can accumulate high concentrations of toxic nitrates under certain conditions. The type of soil, availability and the form of nitrogen present in the soil, various environment factors and chemical or physical plant damage influence the amount of nitrate in the plant.
Nitrate levels over 0.9% can result in nitrate toxicity
in horses. Nitrates are converted to nitrite in the gastrointestinal tract. Nitrite causes the production of methemoglobin, a type of hemoglobin that cannot carry oxygen. Thus, the effects of nitrate poisoning result largely from oxygen starvation or, in effect, suffocation. Preservation as hay does not reduce nitrate levels. Once nitrate levels are high at cutting, they remain high in the hay.