Influence of Cracked, Coarse Ground or Fine Ground Corn on Digestion, Dry Matter Intake and Milk Yield in Holstein Cows

Four ruminally cannulated Holstein cows (526±41 kg) with 112 d in milk were used in a 4x4 Latin square design. To evaluate the influence of corn processing on performance and digestive function, four dietary treatments were compared: 1) steam-flaked corn (SFC, density = 0.31 kg/l); 2) coarsely-ground corn (DR-CG, density = 0.55 kg/l); 3) medium-coarsely ground-corn (DR-MG, density = 0.50 kg/l) and 4) fine ground corn (DR-FG, density = 0.45 kg/l). There were no effect (P>0.05) of coarseness of grind of dried rolled corn (DRC) on DMI, digestion or milk yield. Finely ground corn increased ruminal propionate concentration and decreased ruminal pH and acetate-to-propionate ratio. SFC increased (P<0.05) total tract digestion of OM, NDF, starch and DE content of diet. Even though, no difference in DMI and milk yield were observed among treatments, SFC increased (P<0.05) milk efficiency. It is concluded that feeding value of dry-processed corn to lactating cow diets was not enhanced by reducing the particle size of the kernels beyond to that obtained following coarse rolling.