Acid-base status of ammonia-poisoned steers

Abstract

Although several studies on ammonia poisoning have been carried out, there is a lack of information on acid-base balance status in ammonia-poisoned cattle. Twelve crossbred steers received intraruminally 0.5 g of urea per kg of body weight in order to induce a clinical picture of ammonia poisoning. Blood samples were collected throughout the trials in order to determine the blood ammonia, lactate, and perform blood gas analysis. All cattle presented a
classical clinical picture of ammonia poisoning, with a blood ammonia concentration rising progressively from the beginning until reaching higher values at 180 min (27 ± 3 to 1719 ± 101 µmol L^-1), with a similar pattern occurring with blood L-lactate levels (1.7 ± 0.3 to 26.0 ± 1.7 mmol L^-1). The higher the blood ammonia concentration the higher the blood L-lactate levels (r = 0.86). All animals developed metabolic acidosis, as blood pH lowered to 7.24 ± 0.03. The steers tried to compensate the metabolic acidosis mainly through the use of blood buffers and respiratory adjustments by lowering the pCO₂ levels in the blood to 32.8 ± 2.0 mm Hg.