Water intake and feeding with whole milk accentuate metabolic acidosis in calves with induced osmotic diarrhea

Abstract

Sucrose- and diuretics-based protocols are widely used to induce osmotic diarrhea and dehydration in calves, but they fail to cause metabolic acidosis. In previous studies, calves were fed milk replacers and deprived of water. In this study, we assessed the water, electrolyte, and acid-base imbalances in calves that were fed whole milk and were not completely deprived of water during the induction period. Healthy, male Holstein calves aged 10-12 days were assigned to two groups: free access to water (FWG; n=17) and water deprivation at night (DWG; n=21); and osmotic diarrhea was induced with sucrose added to milk, spironolactone (2mg kg-1) and hydrochlorothiazide (2mg kg-1) orally every 8h for 48h. pH, pCO2, HCO3-, BE, Na+, K+, Cl-, SID3, TPP, AG, Atot, glucose, L-lactate, D-lactate, SIG, and percentage change in plasma volume were measured in venous blood samples taken at 0, 24, and 48h. Data were analyzed using two-way repeated measures ANOVA. Calves showed diarrhea, mild (FWG) to moderate (DWG) dehydration, hyponatremia, and moderate (FWG) to severe (DWG) metabolic acidosis. AG and D-lactate levels were higher and SIG was lower in the DWG, and there was no hyper-L- or D-lactatemia. The magnitude of metabolic acidosis was similar to that observed in natural cases of diarrhea. The protocol for inducing osmotic diarrhea and dehydration should be applied to calves that are fed whole milk and are not completely deprived of water.