Effect of processing of supplemental corn on metabolizable protein of beef cows grazing winter wheat pasture

Abstract Text: Eight ruminally and duodenally cannulated, Angus-crossbred cows (587 ± 49.0 kg) grazing winter wheat pasture (WWP) were used in a completely randomized design with the objective of evaluating effects of processing of supplemental corn (ground vs. steam-flaked) on forage intake and metabolizable protein. The experiment was conducted from March 23 through April 6, 2015. Cows grazed a single WWP with ground corn (GC) or steam-flaked corn (SFC) offered individually at 0.4% of BW, once daily at 0700 h. Forage DM intake and total DM intake were greater (P = 0.01) for SFC than for GC supplementation. Forage OM, CP, and NDF intake was greater (P = 0.01) for SFC than for GC supplementation. Total OM, CP, and NDF intake was greater (P < 0.02) for SFC than for GC supplementation. Although feed CP flow to the small intestine was not affected (P = 0.97) by corn processing method, microbial CP synthesis was greater (P = 0.01) for SFC than for GC supplementation. Therefore, total CP flow to the small intestine (metabolizable protein) was greater (P = 0.03) for SFC than for GC supplementation. Total tract digestibility of OM, CP, and NDF (expressed as g/d) were greater (P < 0.02) for SFC than for GC supplementation. In conclusion, forage intake, microbial protein synthesis, and metabolizable protein improved by steam-flaking as compared to grinding supplemental corn for cattle grazing WWP. Steam flaking as compared to grinding supplemental corn may improve performance of cattle grazing WWP by improving forage intake and microbial CP synthesis.

Keywords: grain processing, metabolizable protein, winter wheat pasture