EFFECT OF ENZYME TREATMENT OR STEAM-FLAKING OF SORGHUM GRAIN ON LACTATION AND DIGESTION IN DAIRY-COWS

Effects of addition of a fungal enzyme (reported to have amylolytic an d proteolytic activities) to dry-rolled or steam-flaked sorghum grain (40% of dietary DM) were tested for 70 d with 36 lactating Holstein co ws in a 2 x 2 factorial arrangement of treatments. Compared with dry-r olling, steam-flaking resulted in increased yield of milk, milk protei n, and 3.5% FCM; percentage of milk protein; and efficiency of feed ut ilization (FCM/DMI). Milk casein (as a percentage of milk N) was not a ltered, but milk urea N was lower, for cows fed steam-flaked sorghum. With steam-flaking, milk fat percentage decreased, short-chain fatty a cids (C-8 to C-14) increased, but long-chain fatty acids (C-16 to C-18 ) were not affected. No yield parameters were altered by enzyme additi on, 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 dig estibility, but digestibilities of DM, OM, CP, and NDF were greater wh en flaked grain was treated with enzyme, resulting in significant inte raction 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.