Nutritional Responses of Calves Fed Milk or a Milk Replacer

Abstract

The nutritional responses of young male dairy calves fed whole milk or a commercial milk replacer were measured from 3 days postnatal to 14 wk age of weaning. Treatments were whole milk or milk replacer at 12% or 8% of body weight or at a constant intake of 8 liters daily. Chopped wheat straw was fed ad libitum. Preputial resection was performed in the calves during the first week of life to allow for clear separation of urine and feces during the experiment. The relationships between the excretion of several nitrogenous compounds and nitrogen balance were studied. Calves went through four nitrogen balance trials during the 13-wk experimental period. Most of the differences in changes of body weight and daily gain were related to amounts of whole milk or milk replacer fed. With 8% milk replacer less straw was consumed than with the 8% whole milk. Less nitrogen was digested and retained on milk replacer. Fecal nitrogen excretion was increased by the high intake of milk replacer. Milk replacer promoted growth comparable to whole milk, but its protein was not of equal nutritional value. Consistent changes across all balance periods were the effects on the excretion of total urinary nitrogen. A more critical evaluation of the nitrogenous components of urine may be useful in evaluating nitrogen metabolism in the young ruminant. © 1978, American Dairy Science Association. All rights reserved.