Influence of Sorghum Grain Processing on Performance of Lactating Dairy Cows

Abstract

Thirty-six lactating Holstein cows (80 DIM) were divided into four groups to compare steam-rolled com with a density of 489 gIL, steam-flaked sorghum grain (360 gIL), dry-rolled sorghum grain (643 gIL), and an equal mixture of dry-rolled and steam-flaked sorghum grain. Each grain treatment constituted 42% of the TMR. A 14-d pretreatment period was used to allot cows to treatment and to adjust treatment means by covariar.ce analysis. Treatment was for 80 d and included a 14-d digestibility trial using Cr203 as a marker. Intake of DM was higher for mixed than for flaked sorghum. Milk yield, FCM yield, and milk fat percentage were not altered by treatment, but cows fed steam-flaked sorghum had higher percentages of protein, lactose, and SNF in milk and greater milk protein yield than those fed dryrolled sorghum. Percentages of milk lactose and SNF were greater for cows fed flaked sorghum than for those fed steamrolled com or the sorghum mixture. Digestibility of OM was higher for flaked sorghum than for steam-rolled com or rolled sorghum, and digestibilities of CP and NDF were highest for dry-rolled sorghum. Total tract starch digestibility was lowest for cows fed dry-rolled sorghum (70%), highest (92%) for those fed steam-flaked sorghum, and intermediate (82%) for those fed rolled com and the