Dry Matter, Crude Protein, and Starch Degradability of Five Cereal Grains

Degradability of starch from com, milo, wheat, barley, and oats was determined in vitro using a 6O-min incubation in a glucoamylase enzyme. Grains were ranked oats, then wheat, barley, com, then milo with 60-min starch degradabilities of 28,24, 18, 13, and 9%, respectively. Six ruminally fistulated steers were used to determine in situ degradabilities of OM, CP, and starch in the five grains. Grains were incubated ruminally for 2, 4, 6, 8, 12, 24, and 48 h in dacron bags (50-J1Il1 pore size). With the exception of oats, grains were ranked similarly for OM, protein, and starch degradability. Based on ruminal availability calculated assuming 6%/h passage rate, grains were ranked: for OM, wheat, then oats, barley, com, then milo with ruminal availability of 88, 87, 78, 54, and 38%, respectively; for CP: oats, then wheat, barley, com, then milo with rumi- nal availability of 98, 95, 91, 70, and 57%, respectively; and for starch: oats, then wheat, barley, com, then milo with ruminal availability of 98,95,90,62, and 49%, respectively. This information may aid in synchronizing degradation of protein and starch in the rumen to improve lactation performance.