Influence of flake density on the comparative feeding value of a barley-corn blend for feedlot cattle.

Ninety-six medium-frame crossbred steers (209 kg) were used in an 86-d feeding trial. Dietary treatments consisted of a 92% concentrate diet containing 76.15% (DM basis) grain as 1) steam-flaked barley (SFB), flake density (FD) = .26 kg/L; 2) blend of 2/3 barley and 1/3 corn steam-flaked (SFBLEND), FD = .36 kg/L; 3) SFBLEND, FD = .31 kg/L; 4) SFBLEND, FD = .26 kg/L. There were no treatment effects (P > .10) on growth performance of feedlot steers or NE value of the diet. Weight gain averaged 1.46 kg/d. Feed efficiency was in close agreement (101%) with expected values based on observed DMI and tabular dietary NE values. Treatment effects on characteristics of ruminal and total tract digestion were evaluated using four Holstein steers (280 kg) with cannulas in the rumen and proximal duodenum in a 4 x 4 Latin square design. Ruminal digestibility of OM (P < .01), starch (P < .01), and feed N (P < .10) increased, and ruminal N efficiency (duodenal nonammonia N/N intake, P < .01) decreased (linear component) with decreasing FD. Net microbial N flow to the small intestine was greater (P < .05) for SFB than for the SFBLEND. Total tract digestion of OM (P < .01), starch (P < .05), and DE (P < .05) was greater for the SFBLEND than for SFB. There were no treatment effects (P < .10) on postruminal and total tract digestibility of N. We conclude that blending barley and corn before flaking will have very little impact on the feeding value of the grains compared with flaking the grains separately.