The objective of the study was to test the tolerance of a rice-based oral rehydration formula when fed to calves. Six healthy Holstein calves, 1 week of age, were fed the formula instead of milk replacer for 3 days. Pre-and posttreatment results of clinical examination and laboratory parameters were compared. Vital signs, attitude, appetite, clinical hydration status, urine specific gravity, and most routine serum biochemistry test results did not vary and remained within the normal range. Five of the 6 calves developed diarrhea when fed the rice-based formula, which was accompanied by a reduction in fecal pH and presence of reducing sugars in the feces. This effect was reversed when calves were returned to the milk replacer diet at the end of the study. Diarrhea was accompanied by increased water consumption, which allowed the calves to maintain normal hydration status. These results suggest that calves are unable to properly digest the rice-derived carbohydrate, and this type of formula is not recommended for oral rehydration of calves.Key words: Carbohydrate digestion; Diarrhea; Fluids.O ral fluid therapy has long been recognized as an important treatment modality for the correction of dehydration due to diarrhea in calves. Traditionally, products for oral rehydration have been composed of glucose and sodium-containing salts, similar to what has been recommended in the past by the World Health Organization for use in children. These solutions promote enterocyte uptake of water via sodium and glucose-mediated cotransport.
1,2Initially, isotonic solutions were recommended, which limited the glucose content and thus the caloric density of the product. More recently, hypertonic solutions, with higher glucose concentration, have been shown in calves to provide increased caloric intake without exacerbating intestinal fluid losses, as was originally feared.1,3 An alternative approach, currently employed in oral rehydration products used in human patients, is to avoid the ''osmotic penalty'' of increased glucose content by providing the carbohydrate in polysaccharide form, replacing the glucose with rice powder.1,4,5 Studies in human patients have shown successful rehydration and reduced stool output after treatment with rice-based products. Rice-based products are not widely used in bovine medicine. However, because of their availability and utility in other species, clinicians or producers may begin to use them. Numerous studies of milk replacer formulae conducted in the 1950s through the 1970s suggested that calves do not have the enzymes necessary to utilize dietary starch or maltose, the principal carbohydrates in rice.7-12 Therefore, rice-based oral rehydration solutions may result in maldigestion in calves. The purpose of this study was to evaluate the tolerance of a rice-based oral rehydration formula in healthy calves when fed at normal (approximately isosmotic) concentration, and to determine the response to a higher caloric density (2 times isosmotic) formula.
Materials and MethodsSix healthy Holstein calv...