Corn Grain and Liquid Feed as Non-Fiber Carbohydrate Sources in Diets for Lactating Dairy Cows: Digestibility Trial

We predicted that adding a sugar-based liquid feed (LF) additive would improve the non-structural carbohydrate (NSC) digestibility of corn grain ground coarsely compared to finely ground corn. The NSC sources are necessary in dairy cattle diets because they provide readily available energy that can enhance rumen microbial activity and forage utilization. This study used five rumen cannulated cows milked twice daily at The Ohio State University’s Waterman Dairy Center in a 5 x 5 Latin square design to test for total tract digestibility of neutral detergent fiber (NDF) and organic matter (OM), as well as ruminal concentrations of ammonia and volatile fatty acid (VFA). All diets contained a constant 24% corn silage, 16% alfalfa hay, and 6% grass hay that were adjusted to maintain 36% NDF, 20.3% forage NDF, and 36% NSC. The control diet contained steam flaked corn (SFC) and the other diets contained either finely (FGC) or coarsely ground corn (CGC), factorialized with or without 3.5% LF (Quality Liquid Feeds, Dodgeville, WI). Treatment periods consisted of two weeks, and chromic oxide was dosed via the rumen as a digestibility marker. The LF increased butyrate with FGC but not CGC. Finer particle size and SFC reduced (P < 0.05) ruminal ammonia concentrations, and the finer particle size reduced ruminal pH. There were no treatment effects on digestibilities of dry matter (65.9%), OM (67.7%), and NDF (54.9%). Milk fat (3.51%) and protein (2.85%) were similar among diets, but milk urea nitrogen was lower with finely ground corn. The SFC and FGC seemed to be more rapidly fermented in the rumen, without adversely affecting intake or digestibility. Liquid feed appeared to be more beneficial with FGC than CGC.Quality Liquid Feeds, Dodgeville, WINo embarg