High dietary calcium causes metabolic alkalosis in egg-type pullets

One hundred sixty healthy egg-type pullets were randomly divided into 2 groups at 35 d of age. The groups were fed either with a normal-calcium (control, 8.5 g of Ca/kg) diet or with a high-calcium (HC, 36.3 g of Ca/kg) diet, respectively. The experiment lasted for 32 d. The healthy situations of the egg-type pullets were observed. Blood gas values and serum and urine electrolyte content were determined. The HC diet caused watery excreta in pullets. The pullets raised on the HC diet had significantly higher blood pH, bicarbonate, base excess, and significantly lower blood partial pressure of oxygen, partial pressure of carbon dioxide, and oxygen saturation than the pullets raised on the control diet. Phosphorus and potassium decreased; meanwhile, calcium increased in the HC group as compared with the control group. Sodium, magnesium, and chloride in serum had no significant difference between the HC group and the control. The pullets raised on the HC diet had significantly higher urine pH than the pullets raised on the control diet. For HC pullets, urinary concentration and 24-h urinary excretion of calcium and chloride was significantly higher, and magnesium, inorganic phosphorus, and sodium was significantly lower than that of the control pullets. It is concluded that some metabolic disorders associated with high dietary calcium in egg-type pullets may be related to a state of metabolic alkalosis.