EFFECT OF SUBSTITUTING STEAM-FLAKED SORGHUM FOR CONCENTRATE ON LACTATION AND DIGESTION IN DAIRY-COWS

Thirty-five lactating cows (110 DIM), allotted to five dietary treatments for 70 d, were fed 0, 15, 30, or 45% of dietary DM as steam-flaked sorghum grain (360 g/L) in place of equal amounts of a mixture (DM basis) of 40% steam-rolled corn, 13% rolled barley, 20% wheat mill run, and 27% ground beet pulp in four diets. Thinly flaked sorghum grain (283 g/L) was also fed at 15% of dietary DM. The DMI tended to increase as flaked sorghum increased. Yields of milk and milk protein and percentages of milk protein and SNF increased linearly as sorghum increased. Milk yield of cows fed 15% of DM as the thinly flaked sorghum was higher than for cows fed the 360 g/L flake at 15% and similar to that of cows fed the 360 g/L flake at 30 or 45%. Feed efficiencies and changes in BW and body condition score were unaffected by treatment. As steam-flaked sorghum increased, digestibilities of DM, OM, ADF, NDF, and CP tended to decrease, except for the thinly flaked sorghum fed at 15% of DM. Apparent starch digestibility in the total tract was unaltered by diet. The 30 to 45% of DM fed as steam-flaked sorghum grain (360 g/L) increased yields of milk and milk protein, and thinly flaked sorghum (283 g/L) fed at 15% of DM increased milk yields over that of the control diet or that with the 360 g/L flake at 15% of DM.