Hybrid rye grain inclusion strategies as a replacement for corn grain in finishing cattle diets: effects on growth performance and carcass characteristics.

Abstract

Two experiments were conducted to evaluate the effects of feeding dry-rolled hybrid rye grain (DRRG) as a replacement for dry-rolled corn (DRC) in beef cattle finishing diets. Two inclusion strategies for rye grain (RG) were evaluated: a total replacement of DRC for a limited time and a partial replacement during the entire feeding trial for Exp. 1 and 2, respectively. In Exp. 1, primarily Angus steers [n = 110, initial shrunk body weight (BW) 391 ± 31.5 kg] were blocked by BW and pen location in 7 blocks and assigned to either 1-A) DRC as the sole grain during the entire finishing (DRC), or 1-B) DRRG during the initial 46 d (replacement phase) and then switched to DRC (DRRG/DRC). In Exp. 2, primarily Angus steers (n = 44, initial shrunk BW 436 ± 41.0 kg) were blocked by BW and pen location in 4 blocks and assigned to either 2-A) DRC as the sole grain (DRC), or 2-B) the dietary grain component was a blend of one-third DRRG and two-thirds DRC (DM basis), during the entire feeding trial (MIX). Steers were fed for a total of 144 and 119 d in Exp. 1 and Exp. 2, respectively. Pen was the experimental unit, and data were analyzed as a randomized complete block design for both experiments. In Exp. 1, DRRG-fed steers had 18% less dry matter intake (DMI; P = 0.01) and 13% less average daily gain (ADG; P = 0.01) during the replacement phase. Cumulatively, steers initially fed with the DRRG-based diet tended to consume less than steers continuously fed the DRC-based diet (P = 0.08). However, cumulative ADG, final body weight (FBW), and hot carcass weight (HCW) did not differ (P ≥ 0.16). Steers fed DRRG tended to have lesser marbling scores and USDA Yield Grades (P = 0.08). In Exp. 2, Steers fed MIX tended to have less DMI expressed as % of BW (P = 0.09); no other differences were observed for growth performance or carcass characteristics. In conclusion, both alternatives serve to include rye in feedlot diets, with minimal effects on cumulative performance. However, in the current experiment total replacement of DRC with DRRG for a portion of the feeding period reduced feed intake, body weight gain, and carcass quality.