Hammer-milled Rye and Inter-planted Corn and Forage Sorghum Blends as Alternatives to Corn-based Ingredients for Growing Beef Steer Diets

Abstract Corn is a staple cattle feed ingredient across the Midwest; however, cereal hybrid rye and forage sorghum are viable alternatives to reduce feed costs and mitigate production risk. Direct chopping forage sorghum can be difficult, as harvest materials are often too wet for optimal harvesting and fermentation. Planting forage sorghum and corn in the same field could result in greater DM capture and similar starch concentration compared to forage sorghum alone. The objective of this study was to determine the effects of dry-rolled corn (DRC) compared to hammer-milled hybrid rye (RYE) fed with either corn silage (CSL) or forage sorghum/corn silage blend (SCO) in diets fed to beef steers during a 63-d growing study. Starch (DM basis) concentrations in CSL and SCO were 30.1% and 30.8%, respectively. Simmental × Angus crossbred steers (n = 224; initial BW = 289 ± 62.6 kg) were blocked by initial BW and pen location into 6 blocks (n = 24 pens, 8 or 10 steers/pen). At study initiation, steers were implanted with 36 mg zeranol, treated for internal and external parasites, and vaccinated against clostridial and respiratory disease. Pens were randomly assigned to one of four treatments in a 2 x 2 factorial treatment arrangement. Factors were grain source (DRC or RYE; fed at 21% of diet DM) and silage type (CSL or SCO; fed at 55% of diet DM), resulting in four treatments: DRC/CSL; DRC/SCO; RYE/CSL; and RYE/SCO with six pens per treatment. Body weights were collected on days 35 and 63. A 4% shrink was applied to all BW measures. Data were analyzed as an RCBD with grain source, silage type, and their interaction as fixed effects and block as a random effect; pen was the experimental unit. Feeding DRC increased ADG 6.8% through d35 (P = 0.04), tended to increase DMI from d1-35 and d36-63 (P ≤ 0.09), and cumulatively increased DMI by 1.8% (9.57 and 9.40 kg/d for DRC and RYE, respectively; P = 0.01). Feeding SCO increased DMI from d1-35 and d36-63 (P ≤ 0.05) and cumulatively increased DMI 2% (9.39 and 9.58 kg for CSL and SCO, respectively; P = 0.01). Grain source and silage type tended to interact for cumulative ADG and G:F. No differences for ADG or G:F were noted between grain source when CSL was fed, but feeding RYE with SCO tended to reduce cumulative ADG (1.60, 1.61, 1.66, and 1.55 kg/d for DRC/CSL, RYE/CSL, DRC/SCO, and RYE/SCO, respectively; P = 0.09) and cumulative G:F (0.170, 0.175, 0.173, and 0.165 for DRC/CSL, RYE/CSL, DRC/SCO, and RYE/SCO, respectively; P = 0.09). Under the conditions of this experiment, feeding RYE with CSL but not SCO was as effective as DRC, and SCO was a suitable alternative to CSL.