Preliminary study of the relationships between the blood mineral composition of dairy cows and the milk and milk fat yield simultaneously obtained

A preliminary study of the relationships between the blood mineral composition and the simultaneous milk and milk fat yield was made on the basis of 217 blood and milk samples. The effects of blood sodium, potassium, calcium, chlorine, phosphorus, Na/K and Ca/P ratios and the excess of cations in the blood were investigated separately. The inorganic cations, except potassium, appeared to show in general a positive influence and the inorganic anions a negative influence on the milk and milk fat yields. Some of the relationships noticed in this study might indicate actual effects of blood minerals on milk secretion. Some others, however, might be secondary, and possibly related to variations in hormonal control. The fluctuations in blood potassium and blood Na/K ratio, for example, might primarily indicate the efficiency of adrenal and renal function.