331 Effects of Dried Distillers’ Grains Cube Supplementation Rate on Voluntary Intake and Digestibility of Bermudagrass Hay Fed to Growing Heifers

Abstract

The objective of this study was to evaluate supplementation rates of dried distillers’ grains cubes (DDGS) on voluntary intake (DMI), rate and extent of digestibility, and blood parameters of growing Charolais-cross heifers (BW = 286 ± 28.9 kg) fed ad libitum bermudagrass (Cynodon dactylon) hay. For the 29-d study, heifers were randomly assigned to one of four supplementation treatments: 1) Control, no supplement (n = 6); 2) Low, supplemented 0.90 kg/d (n = 6); 3) Intermediate, supplemented 1.81 kg/d (n = 5); or 4) High, supplemented 3.62 kg/d (n = 6). Heifers were offered supplement each morning in individual stalls. From d 15 to 25, heifers were dosed twice daily with titanium dioxide in gelatin capsules (10 g/d), and fecal samples were collected via rectum at time of dosing from d 22 to 25 to estimate fecal output. Post-dosing, fecal sampling continued over 96-h from d 25 to 29 to determine passage rate (Kp) via titanium dioxide analysis. Blood was collected from each animal on d 26 via jugular venipuncture before supplementation, and 4 and 8-h post-supplementation for analysis of blood urea N (BUN), lactate, and glucose. Samples of feces, hay, and supplement were incubated in rumen-cannulated Holstein steers (n = 4; BW = 281 ± 29.5 kg) for 576-h to estimate digestibility with indigestible neutral detergent fiber as an internal marker. Data were analyzed by ANOVA using the mixed procedure of SAS (SAS Inst. Inc. Cary NC), with treatment least-squares means separated using orthogonal polynomial contrasts. Increasing DDGS linearly (P < 0.01) decreased forage DMI linearly, but linearly increased Kp, total diet DMI, and total diet digestibility. Linear increases (P ≤ 0.02) in glucose, lactate, and BUN were likewise observed with increasing DDGS. Increasing DDGS supplementation to growing calves consuming bermudagrass hay may increase productivity while reducing forage intake.