[Acid-base equilibrium in experimental acid indigestion in cattle]

Blood and urine acid-base parameters were investigated in 4 heifers with acid indigestion produced by intraruminal infusion of sugar in a dose of 12 g/kg b.wt. Observations were carried out for 9 days after sugar administration. It was found that rumen acidosis was accompanied by disturbances in blood acid-base balance characteristic of partially compensated metabolic acidosis. The most pronounced changes in acid-base parameters were observed within the first 24 hours after sugar infusion, i.e. during rapid increase of lactic acid levels in blood. These changes were reflected by a decrease of blood pH values to 7.138-7.275 reduction in standard bicarbonate to 12.2-17.0 mmol/l and deficiency in base excess ranging from 9.3 to 16.7 mmol/l. The maximum reduction in partial pressure of CO2 to 4.35-4.79 kPa occurred during the second day of the experiment. The duration of acid-base disturbances depended on their intensity in individual animals and oscillated between 4 and 9 days after sugar administration. When acidosis subsided, acid-base balance returned to normal or showed a tendency toward blood alkalization. The observed decrease of pH values in urine to 5.42-5.74 and renal acid excretion from 170 to 299 mmol/l indicate a significant role of kidney function in the correction of metabolic acidosis.