Our objectives were to 1) investigate the difference in chemical composition and disappearance kinetics between loose dried distillers’ grains (DDG) and extruded DDG cubes and 2) evaluate the effects of supplementation rate of extruded DDG cubes on voluntary dry matter intake (DMI), rate and extent of digestibility, and blood parameters of growing beef heifers offered ad libitum bermudagrass (Cynodon dactylon) hay. To characterize the changes in chemical composition during the extrusion process, loose and extruded DDG were evaluated via near-infrared reflectance spectroscopy, and dry matter (DM) disappearance kinetics were evaluated via time point in situ incubations. Extruded DDG cubes had greater (P ≤ 0.01) contents of fat, neutral detergent insoluble crude protein, and total digestible nutrients, but lower (P ≤ 0.01) neutral and acid detergent fiber than loose DDG. Additionally, the DM of extruded DDG cubes was more immediately soluble (P < 0.01), had greater (P < 0.01) effective degradability and lag time, and tended (P = 0.07) to have a greater disappearance rate than loose DDG. In the 29-d supplementation rate study, 23 Charolais-cross heifers were randomly assigned to one of four supplemental treatments: 1) Control, no supplement; 2) Low, 0.90 kg DDG cubes/d; 3) Intermediate, 1.81 kg DDG cubes/d; or 4) High, 3.62 kg DDG cubes/d. Titanium dioxide was used as an external marker to estimate fecal output and particulate passage rate (Kp). Blood was collected from each animal to determine supplementation effects on blood metabolites. Indigestible neutral detergent fiber was used as an internal marker to assess the rate and extent of hay and diet DM digestibility (DMD). Increasing supplementation rate increased Kp and total diet DMI linearly (P < 0.01), yet linearly decreased (P < 0.01) hay DMI. Hay DMD decreased quadratically (P < 0.01), while total diet DMD increased linearly (P < 0.01) with increased DDG cube inclusion. Supplemented heifers had greater (P = 0.07) blood urea nitrogen concentrations than control animals 4 h post-supplementation. Intermediate and high rates of supplementation resulted in lower (P < 0.01) serum non-esterified fatty acid concentrations post-supplementation than control heifers. Concentrations of serum glucose and lactate were greatest (P ≤ 0.06) 8 h post-supplementation. Our results suggest that extruded DDG cubes may be an adequate supplement for cattle consuming moderate-quality forage, and further research is warranted.
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.
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