Source of carbohydrate and protein in the diet of recently weaned dairy calves

The Dairy NRC (2001) suggests that digestible fiber is needed in the diet of calves. However, in our recent research, live body weight average daily gain (ADG) decreased when starch from corn was replaced with sources of digestible fiber; i.e. soybean hulls, wheat middlings, or distiller's dried grains with soluble (Hill et al., 2008; Suarez-Mena et al., 2012). Additionally, limited recent research has not demonstrated consistent ADG responses to manipulating a calf's diet for metabolizable protein compared to control diets that were predominately corn and soybean meal (Hill et al., 2007). The objective was to measure diet digestibility as a potential means to explain differences in performance when different carbohydrate and protein sources were fed to calves.