Potassium Depletion in Lactating Dairy Cows

Abstract

A change-over feeding experiment involving eight individually fed lactating dairy cows was conducted to study potassium deficiency symptoms in lactating cows. Potassium deficient (0.06% and 0.15%K) and potassium adequate (0.80% K) rations were tested and responses to both compared. The deficient animals showed a marked decrease in feed intake, symptoms of pica, loss of hair glossiness, decreased pliability of hides, significantly lower blood plasma and milk potassium, and higher hematocrit readings. A relatively greater decrease of potassium concentration in milk over blood plasma was observed when the deficient ration was fed. Higher and significantly inverse relationships between potassium and sodium content of the milk when fed the deficient ration in contrast to the adequate ration were indicated. The reduced potassium and simultaneous increase in sodium elimination through milk probably helped the animal maintain a higher level of tissue potassium. Total cationic concentrations (K+ + Na+ + Mg++) in milk, blood plasma, and whole blood remained essentially the same, during both periods.