The Physiological Effect of Rations Restricted Principally or Solely to the Alfalfa Plant: I. The Calcium, Phosphorus and Nitrogen Metabolism of Dairy Cattle

Abstract

Summary We have reported a series of metabolism studies in which the nitrogen, calcium and phosphorus balances of dairy cattle were determine for 12 ten-day periods, during which the daily milk yields varied from approximately 9 to 18 kgm. The rations fed consisted of alfalfa hay with and without supplements of starch, linseed oil meal, or di-sodium phosphate. According to our data, cows in the early lactation period were usually in positive calcium balance; in negative nitrogen balance when the hay contained less than 2.0 per cent nitrogen; and always in negative phosphorus balance when only alfalfa hay was fed. Feeding di-sodium phosphate changed the negative phosphorus balances to slightly positive balances. We have also included a general discussion of some of the factors which may be involved in rations restricted principally or solely to alfafa.