Effect of Enzyme Treatment or Steam-Flaking of Sorghum Grain on Lactation and Digestion in Dairy Cows

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Abstract
Effects of addition of a fungal enzyme (reported to have amylolytic and proteolytic activities) to dry-rolled or steam-flaked sorghum grain (40% of dietary DM) were tested for 70 d with 36 lactating Holstein cows in a 2 x 2 factorial arrangement of treatments. Compared with dry-rolling, steam-flaking resulted in increased yield of milk, milk protein, and 3.5% FCM; percentage of milk protein; and efficiency of feed utilization (FCM/DMI). Milk casein (as a percentage of milk N) was not altered, but milk urea N was lower, for cows fed steam-flaked sorghum. With steam-flaking, milk fat percentage decreased, short-chain fatty acids (C8 to C14) increased, but long-chain fatty acids (C16 to C18) were not affected. No yield parameters were altered by enzyme addition, except that the percentage of lactose in milk increased (5.02 vs. 4.96%). Steam-flaking of sorghum grain increased digestibilities of DM, OM, and starch (63 vs. 57%; 66 vs. 59%; and 98 vs 83%, respectively) compared with dry rolling. Enzyme addition did not affect starch digestibility, but digestibilities of DM, OM, CP, and NDF were greater than flaked grain was treated with enzyme, resulting in significant interaction effects. This study demonstrated higher milk and milk protein yields for cows fed steam-flaked sorghum than for cows fed dry-rolled sorghum, but addition of a sorghum-specific enzyme had no significant effect.