Blood indexes of nitrite toxicosis in dairy cows

Abstract

Nitrate (NO_ 3) and nitrite (NO_ 2) can be ingested with water and feeds and NO_ 2 can be produced from NO_ 3 by rumen and intestinal microbes. Moreover,NO_ 3 and NO_ 2 are endogenously produced by cells of various tissues from nitric oxide (NO) and arginine (Passi, 2000). Toxicity of NO_ 3 is casued by the reduction to NO_ 2 in the rumen environment. This ion competes with superoxide for hemoglobin (Doyle et al., 1982), producing methemoglobin (MtHb), which does not carry oxygen. The reaction is reversible, but the transient hypoxia can be exacerbated if the amount of ingested nitrates is high, causing fall of blood pressure and increase of heart rate........

Keywords

• Nitrites, NOx, Methemoglobin, Cows