Mineral nutrition, calcium, phosphorus, magnesium, and potassium interrelationships.

There are over 70 known mineral inten'elationships in which an additional dietary quantity of one mineral element wilt influence absowtion or utilization of another mineral element. As the animal ages, the readiness of availability of stored mineral dements in the bone decreases. Animals do adapt to reduced dietary intake of minerals as shown for Ca by reducing fecal excretion and increasing absorption. The adaptation, however, may occur simultaneously with a reduction in milk production. Borderline deficiency or insufficiency o£ mineral elements leads to decreased feed intake and milk production. Diagnosis is extremely difficult. A large proportion ok commonly used feedstuffs are below the required concentration of at least one mineral element for high milk production. Since few dairymen know how much of each mineral element is in their cows' diet, milk production may unwittingly suffer from mineral deficiency, insufficiency, or toxicity. Excessive rather than too little dietary Ca during the dry period prior to calving is likely contributing to an increased incidence of milk fever. Basically, blood P must be maintained by absorption from the gut as there is no known specific mechanism/or bone resorption. Therefore, it is important always to include adequate P in the diet. Too little Mg may be causing problems that are not well understood, or widely appreciated. Supplemental K is Received for publication October 1, 1971. t Taken from an invitational paper presented by the senior author at the Sixty-sixth Annual Meeting of the American Dairy Science Association, East Lansing, Michigan. June 20-23, 1971. The research reported herein was supported in part by the American Jersey Cattle Club Research Foundation. " The investigation reported in this paper (715-113) is in connection with a project of the Kentucky Agricultural Experiment Station and is published with approval of the Director. probably indicated on some high concentrate feeding programs. All mineral elements should be considered in ration formulation for high performance and a reduction in mineral nutrition anomalies.