ANN 111: Principles of Animal Nutrition and Feed Technology (2+1)

NITRATES AND NITRITES

Nitrate is a non protein nitrogenous fraction (NPN) present in forages. Nitrate itself is not toxic to animals. The toxic effect on ruminants is caused by the reduction of nitrate to nitrite in the rumen. Recently fertilized plants have higher nitrate levels. Grazing herbage containing more than 700 ppm of nitrate nitrogen / kg dry matter is considered to produce toxic effect by converting to nitrite. Forages and drinking water when contaminated with inorganic nitrates and nitrites cause an acute toxicosis in cattle resulting from formation of methemoglobin. Nitrite is absorbed into red blood cells and combines with hemoglobin (oxygen carrying molecule) to form brown pigment called methemoglobin. Methemoglobin cannot transport oxygen and hence the animal's heart rate and respiration increases, the blood and tissues of the animal take on a blue to chocolate brown tinge, muscle tremors can develop, staggering occurs, and the animal eventually suffocates and die. A high dose of concentrates in the daily ration and adequate feeding or Vitamin A have a protective effect.

Nitrate reduced to Nitrite in rumen to become toxic. Nitrite combines with hemoglobin to form methemoglobin. Methemoglobin can’t transport oxygen. Enhanced heart rate & respiration. Suffocates; die.