A study was conducted to determine the effect of corn (Zea mays L.) grain processing on intake, digestibility of
nutrients and milk production and composition. The effect of extrusion on nutrient digestibility was evaluated in
trial 1, using ground corn as a control. In trial 2, the effect of extrusion on intake was evaluated, comparing extruded
corn of two densities (357 and 308 g L-1) with rolled corn (507 g L-1) as a control. In trial 3, the effects of extrusion
on milk production, digestibility and intake were evaluated; using steam rolled corn and ground corn as controls.
No effects on dry matter and metabolizable energy intakes due to differences in the extruded corn grains were
observed. Digestibility of dry matter, organic matter, crude protein, gross energy and neutral detergent fiber did not
differ among treatments, although a greater digestibility of non-fibrous carbohydrates was observed. Higher milk
production was obtained in treatments including extruded and steam rolled corn (21.4 and 21.6 L d-1), compared to
ground corn (20.5 L d-1) but differences disappeared when standardizing for fat content. Milk composition was not
affected by treatments. Daily protein production was greater (P < 0.01) in treatments including extruded and rolled
corn. Blood parameters (ß-hydroxybutyrate, urea) and milk urea remained within normal reference values. It was
concluded that using extruded corn had no adverse effects on digestibility or forage and total intake with a small
advantage in milk protein yield comparing with ground corn, but without clear differences compared to steam rolled
corn.