Evaluating processing methods of hybrid rye fed to growing beef steers

Crossbred Bos taurus beef steers (n = 150; initial shrunk body weight [BW] = 260 ± 22.2 kg) were used in a 63-d feedlot experiment to evaluate the effects of rolled (RRYE) and ground (GRYE) hybrid rye as replacements for dry-rolled corn (CON) on growth performance and comparative net energy (NE) values in diets fed to backgrounding steers. Rye from a single hybrid (KWS Bono) was processed using either a roller mill or a hammermill to achieve geometric mean particle diameters of 1780 µm and 731 µm, respectively. Three treatments were used in a randomized complete block design (n = 5 pens/treatment; 10 steers/pen), in which dry-rolled corn was completely replaced by RRYE or GRYE. Performance-adjusted NE was calculated using average daily gain (ADG), dry matter intake (DMI), and mean equivalent shrunk BW, and comparative NE values for rye were calculated using the replacement technique. Data were analyzed using the MIXED procedure of SAS 9.4 (SAS Inst. Inc., Cary, NC), with pen as the experimental unit. Treatment effects were tested using preplanned contrasts of CON vs. RYE and RRYE vs. GRYE. No differences between CON and RYE were detected (P ≥ 0.10) in ending BW, BW gain, ADG, DMI, gain:feed (G:F), or performance-adjusted NE for maintenance or gain (NEm, NEg). Steers fed GRYE tended to have greater BW gain (P ≤ 0.07) and ADG (P ≤ 0.06), with no differences in ending BW, DMI, or G:F compared with those fed RRYE. The concentration of NEg was calculated assuming dry rolled corn has an NEg concentration (Mcal/kg) of 1.49. Estimated replacement NEm and NEg values for RRYE included at 22% of diet DM were 1.91 and 1.25 Mcal/kg, respectively, whereas NEm and NEg values for GRYE were 2.29 and 1.58 Mcal/kg, respectively. Hybrid rye had a similar NE value to corn when fed in a high-forage backgrounding diet.