By Angela Breneman
As we increase our knowledge of modern agronomic practices to help improve forage quality, there are factors to consider for grazing livestock. Nitrate toxicity is a non-infectious condition that can be fatal and results from overconsumption of plants fertilized with nitrogen or from water contaminated with nitrate-containing fertilizers (Thompson 2026). Nitrate poisoning, which can especially affect ruminants, occurs when rumen microbes rapidly convert nitrates in forage to high levels of toxic nitrites.The effects of nitrate poisoning can be chronic or subacute and can cause major setbacks in your grazing cattle herd. This article reviews the Merck Veterinary Manual and other sources to discuss the basics of nitrate toxicity in cattle.
The Cause
Under normal conditions, plants absorb nitrogen from the soil in the form of nitrates during the nitrogen cycle Figure 1. Through the process of photosynthesis and plant metabolism, plants use nitrates to synthesize amino acids, proteins, and other essential compounds required for growth or simply assimilated as non-protein nitrogen. Plants that experience stressors, such as drought, frost, or hail, cannot utilize these nitrates and tend to accumulate them. Many factors, such as soil type, availability of nitrogen in the soil, and chemical damage, will also affect the amount of nitrate uptake by the plant. Certain crops and plants are also more likely to naturally concentrate nitrates (Agricultural Research Service, USDA). See Table 1 below. Plants that experience stressors typically concentrate nitrates in the lower stem or vegetative part of the plant and not the seed (Agricultural Research Service, USDA).
Source : psu.edu