Feeding One-Year Stored Sorghum Silage: Effects of Grain Processing on Intake and Apparent Total Tract Digestibility of Backgrounding Beef Heifers

Abstract This study evaluated the effect of feeding sorghum silage after one-year of storage (SS) based diets, on dry matter intake and nutrient digestibility of beef cattle. A dual-purpose sorghum (ADV2450IG, Advanta seeds, Irving, TX) was harvested (Claas Jaguar 930, Harsewinkel, Germany) at the late-dough stage of grain maturity and processed (PRO) or not (NPR) with a specific SS cracker (196 mm rolls of 125 teeth each, 40% speed differential, 1.1 mm roll gap). Whole-plant was chopped at 15 mm and ensiled in polyethylene ag-bags (60 m long and 2.74 m diameter), for 388 d until the beginning of a 60 d-performance trial which was followed by the digestibility trial. From a performance trial with eight heifers/pen, and 12 total (six per treatment), one heifer (13.5 ± 1 mo and 259,4 ± 38 kg of BW) by pen was randomly selected for the digestibility trial. Two backgrounding diets containing (DM basis), 90.5% SS either PRO or NPR, 6.5% soybean meal (expeller) and 3% supplement (ROC90, Provimi, Argentina); continued to be offered ad libitum for an extra 3 d of adaptation while feed and feces were collected the next 4 d. Feed was individually offered once daily, and orts were collected the following day. Fecal samples were collected twice daily and apparent total tract digestibility (TTD) was determined using uNDF240h as a marker. Data were analyzed as a completely randomized design using pen as the experimental unit, and initial BW as a covariate. No differences among treatments were detected for DM, OM, NDF, ADF, CP and starch intake (P > 0.35). No effects of treatment were observed (P > 0.40) for DM, OM, NDF, ADF, CP and starch TTD. In conclusion, no effects of processing on apparent total tract digestibility were detected when feeding a one-year stored sorghum silage to backgrounding beef heifers.