This will give an idea of the type of color change that is significant. Nitrate Nitrate ion is a normal constituent of plants. Under certain conditions abnormal accumulation of nitrates may occur and cause toxicity in domestic animals. Two environmental conditions which predispose to the accumulation of nitrates in plants are drought and low light levels. Management factors such as fertilization and herbicide treatment with phenoxy acid herbicides will also increase accumulation of nitrates in plants.
Nitrate toxicity is mainly a problem in herbivores, and especially ruminants.
Clinical signs of labored breathing, weak rapid pulse, muscle tremors, weakness and intolerance to exercise are seen. Because fetal hemoglobin is more sensitive to the effects of nitrite, abortions can be caused by levels of nitrate which do not elicit overt signs of toxicity in the dam. Elevated levels of nitrate in forage were responsible for a number of equine abortions in Kentucky during the Spring of 1980. A rapid simple qualitative field test is available to test forages for toxic levels of nitrate. Rapid Field Test for the Presence of Toxic Levels of Nitrate Ion Diphenylamine stock solution is prepared by dissolving 0.5 gm. of Diphenylamine in 20 ml. of water.