Neonatal calf diarrhea is a major source of economic loss to the cattle industry and the leading cause of calf mortality in the United States. Oral electrolyte solutions (OES) are routinely administered to dehydrated calves with diarrhea, and it is widely accepted that OES should contain an alkalinizing agent such as bicarbonate; acetate, propionate, or citrate. We hypothesized that administration of bicarbonate-containing OES induced a sustained abomasal alkalinization in dairy calves, relative to suckling milk replacer or acetate-containing OES. The aim of this study was therefore to determine the effect of suckling 3 commercially available OES on abomasal luminal pH, and to compare the effect of the 3 OES on luminal pH with that produced by suckling milk replacer.
Six male dairy calves (aged 12-31 days of age) with cannulae in the abomasal body were administered the following treatments (60 ml/kg body weight, twice, 12 h apart) in a randomized crossover design: all milk protein milk replacer, two hyperosmotic bicarbonate-containing OES (ENTROLYTE-HE©; BIOLYTE(R), and an isoosmotic acetate-containing OES (ELECTYDRAL©). Abomasal luminal pH was measured every second for 24 h using a miniature glass pH electrode. Data were expressed as least square means for the 24 h recording period, and a P value <0.05 was considered significant.
Suckling of milk replacer rapidly increased mean abomasal luminal pH from 1.3 to 5.8, followed by a gradual decrease to preprandial values by 8 h (mean 24 h pH = 3.22). Suckling bicarbonate-containing OES caused a large and sustained increase in abomasal pH from 1.3 to 7.5; mean 24 h pH was 4.09 for ENTROLYTE-HER and 3.47 for BIOLYTE©, both values were higher than that for milk replacer. Luminal pH returned to preprandial values by 5 h for ENTROLYTE-HER and by 4 h for BIOLYTE©. In contrast, suckling the acetate¬containing OES induced only a mild and transient increase in abomasal pH (mean 24 h pH = 2.11) that was lower that that caused by suckling milk replacer. Luminal pH returned to preprandial values by 3 h for the acetate-containing OES. We conclude that suckling bicarbon ate-contain ing OES results in sustained abomasal alkalinization. Because maintaining a high abomasal luminal pH may facilitate growth of bacterial diarrhea pathogens, administration of bicarbonate-containing OES may increase the severity, duration, and mortality rate of bacterial diarrhea in calves. Based on their effects on abomasal luminal pH, acetate-containing OES are preferred to bicarbonate-containing OES when treating dehydrated calves with diarrhea.