Whey protein digestion in the distal ileum of the preruminant calf

A comparison of milk protein sources in diets of calves up to eight weeks of age

Four dietary ratios of dried skim milk and whey protein concentrate as the primary protein sources in milk replacers were evaluated using digestibility, growth performance, health characteristics, and blood measurements of calves that were 12 to 36 h of age to 8 wk of age. Sixteen Holstein bull calves, housed individually within an environmentally controlled facility, were randomly allotted to diets. Protein sources in the milk replacer were expressed as ratios (percentages) of dried skim milk to whey protein concentrate in diet 1, 100:0; diet 2, 67:33; diet 3, 33:67; and diet 4, 0:100. There were no significant differences in the mean number of days that calves scoured. Apparent biological value and N retention differed among diets over all weeks. Apparent digestibilities and biological values (percentages) over all weeks were diet 1, 82.50 and 67.71; diet 2, 82.85 and 70.15; diet 3, 83.82 and 67.46; and diet 4, 84.03 and 72.25, respectively. Diets varying in the ratio of dried skim milk to whey protein concentrates had no effect on health, growth, or apparent digestibilities in Holstein calves up to 8 wk of age.