Influences of diet and body condition on the nitrogen utilization in the cow

Abstract

SUMMARY: The dietary and individual factors influencing the utilization of digestible nitrogen in the dry cow were studied with numerous rations fed to Friesian cows kept in metabolism stalls.Urinary nitrogen excretion and nitrogen balance were above all influenced by the level of digestible nitrogen intake. They are also correlated to metabolizable energy and digestible potassium intakes.Endogenous urinary nitrogen, estimated by extrapolation, was 30·6 mg N/kg body weight/d or 0·169 W^0·73 g/d with the rations meeting approximately the energy maintenance requirements of the cow.The changes in diet accounted for 80% of the variability of nitrogen balance.A method was worked out for calculating the body condition of the cow from the live-weight variations.The changes in body condition accounted for 11% of the variability of nitrogen balance.