Abstract
Predominantly Angus steers were used in a 147-day randomized complete block design experiment (RCBD) to evaluate the effects of rye processing method on growth performance, feed efficiency, and carcass characteristics. Steers [n = 192, initial body weight (BW) = 410 ± 20.9 kg] were individually weighed and allotted to 1 of 24 pens (n = 8 steers/pen; 6 pens/treatment). Four treatments were used where hybrid rye grain (total ergot alkaloid concentration = 1,007 ppb, DM basis) was processed using three different methods [unprocessed (UP); dry-rolled (DR); or hammer-milled (HM)] fed at 17% of diet DM along with 43% dry-rolled corn (DRC) compared with a control diet containing 60% DRC on a DM basis (CON). Data were analyzed as an RCBD using the GLIMMIX procedure of SAS with treatment as the fixed effect and block (Pen location) as the random effect; pen was the experimental unit. No differences (P ≥ 0.44) were observed among treatments for live final BW or average daily gain (ADG). Dry matter intake (DMI) was greater for HM (12.27 kg) compared with CON and DR (11.84 and 11.48 kg, respectively) with DR having 4.9% less DMI compared with UP (P = 0.01; SEM = 0.200). UP and HM treatments tended to have 4.8% poorer G:F compared with CON and DR (P = 0.07). Dietary treatments did not affect carcass traits, percent empty body fatness (EBF), or final BW at 28% EBF (P ≥ 0.23). Distributions of USDA Quality or Yield grades were unaffected by treatment (P ≥ 0.23), nor was the incidence or severity of liver abscesses (P = 0.25). Estimated NEm and NEg values of the diet for UP (1.90 and 1.26 Mcal/kg, respectively) were reduced compared with CON and DR (1.98 and 1.32 Mcal/kg, respectively), with HM intermediate (P = 0.05, SEM = 0.033 and 0.029 for NEm and NEg, respectively). Net energy values for UP and HM rye were within 7% of current feeding standards when calculated using the substitution method. Rolling increased apparent ingredient NEg for rye by 30.1% compared with UP or HM rye. Processing rye grain by dry-rolling increased dietary net energy values and tended to improve gain efficiency compared with not processing or using a hammer mill. Rye grain can be partially substituted for DRC with negligible impact on growth performance or carcass measures.