Sodium and potassium balances and plasma aldosterone levels in newborn calves.

This paper describes a balance study, performed during the first 7 days of postnatal life on 10 male Holstein x Friesian calves born spontaneously at term. The relationship between sodium and potassium balances and plasma aldosterone levels were assessed during the postnatal period. The animals were put in metabolic cages immediately after birth for 7 days. Intakes of sodium and potassium and their plasma levels, as well as urinary and faecal excretion, were measured daily. Statistical (multiple regression) analysis of the results demonstrated that animal age accounted for 57 p. 100 of the variations observed in the plasma aldosterone levels. Neither intake nor faecal and urinary excretions of sodium and potassium were correlated with plasma aldosterone concentrations in newborn calves. The high plasma levels of this hormone at the time of birth might be a result of labor.