Three cases of accidental acute
fertilizer poisoning in cattle resulted in substantial death loss. Water hauled in tanks previously contaminated with a
nitrogen-based
fertilizer was the source in all cases. In 2 cases, analysis of the water measured
urea at 1,640 and 2,300 ppm and
ammonia-
nitrogen at 640 and 750 ppm, respectively. Confirmation of
urea toxicosis was made by measurement of toxic levels of
ammonia-
nitrogen in the rumen contents (>800 ppm) and blood (>8.0 ppm). In Case 3, no
urea was detected in the water but
ammonia-
nitrogen was measured at 1,670 ppm and
nitrate at 1.1%. Toxic levels of
nitrate were measured in ocular fluid from 2 animals (60 ppm). Rumen contents contained toxic levels of
ammonia-
nitrogen (300 ppm) and a pH of 8.7. Interpretation of
ammonia levels in rumen contents should take into account the source of
ammonia as well as the pH since
urea is more toxic than some
ammonium salts. When the source is unknown, analysis of blood and/or serum
ammonia-
nitrogen instead of rumen content is recommended. The rapid progression of signs to death with
ammonium nitrate poisoning may explain the lower levels of
nitrate attained in ocular fluid than observed with pure
nitrate intoxications.