Relative Occurrence of Toxic Concentrations of Cyanide and Nitrate in Varieties of Sudangrass and Sorghum‐Sudangrass Hybrids1

Abstract

AbstractA field experiment was conducted to determine the concentrations of CN and NO3‐N that could occur in successive aftermaths of recommended varieties of Sudangrass (Sorghum sudanense P. Stapf) and sorghum‐sudangrass hybrids (Sorghum bicolor L. Moench × Sorghum sudanense P. Stapf) when fertilized with frequently used rates of N.Nitrate concentration was affected by N rate, and CN concentration was affected by N rate, variety, and especially height of the forage (P=.05). The overall varietal means for CN concentration were: ‘Trudan II’‐189, ‘Su Chow 34’‐326, ‘Sweet Sioux’‐378, ‘Grazer A’‐396, and ‘Tift’‐402 ppm CN. The probability of CN poisoning was found to exceed that for NO3 poisoning significantly.Attention is called to the special case where toxic concentrations of CN and NO3 coexist in these forages; a poisoning would result in which methemoglobin arising from the NO3 poisoning would be a “built‐in” treatment for the initial and rapid detoxification of CN. Consequently, in this situation NaNO2 injection, to induce a limited methemoglobinemia, should be omitted.We suggest that diagnosis and treatment of symptoms associated with “nitrate poisoning” in animals eating these heavliy fertilized aftermaths or green chop should involve more than clinical judgement. Cyanide poisoning should be confirmed or excluded before treating sick animals for NO3 poisoning.