Nutritive Value of Bacterial Sludge and Whey Powders for Protein in Calf Milk Replacers and on Chromic Oxide as Indicator of Digestibility

Abstract

Twelve male Holstein calves were weaned at 3 days of age and allotted at random to one of three diets which were fed from the 4th through 63rd day of age. Composition of the three diets was (a) 82% dried skim milk powder and 18% tallow as control, (b) 35.6% dried bacterial sludge, 46.7% whey powder, and 17.6% tallow, (c) 30.3% dried skim milk powder, 23.3% dried bacterial sludge, 28.3% whey powder, and 18.1% tallow. To determine dry matter and crude protein digestibility and to measure nitrogen retention, feces and urine were collected quantitatively from the 4th through the 42nd day of age and pooled as four distinct collection periods (4 to 14, 15 to 24, 25 to 33, and 34 to 42 days). Large amounts of whey and bacterial sludge did not increase the incidence of diarrhea and did not affect body weight gain, dry matter digestibility, nitrogen digestibility, and measures of nitrogen retention. Chromic oxide as a marker underestimated apparent dry matter digestibility by about 7% as compared to the total collection technique. Incorporation of chromic oxide before spray-drying the ingredients decreased the recovery in feces, as compared to mechanically mixing the marker in the dry diet prior to feeding. The first technique allowed 86% recovery of the chromic oxide fed and the second one 93%. © 1973, American Dairy Science Association. All rights reserved.