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Effects of dietary forage concentration in finishing diets on growth and carcass characteristics of beef steers
The objective of this study was to evaluate the effect of feeding different levels of forage during the finishing phase of beef production on steer performance, meat quality traits, and production costs. Angus influenced yearling steers (n = 120) were fed finishing diets consisting of three forage levels (20, 30, or 40% of the total ration DM). The concentrate portion of each ration was corn, barley, and modified distillers grains. Forages included corn silage and prairie hay. All steers were fed a 40% forage diet for the first 28-day period and then assigned to one of three treatments: 1) 40% forage, 2) 30% forage, or 3) 20% forage after 30 % forage for 28 days. Steers were blocked by weight and randomly allotted to pen within weight block, with 10 head per pen and four pens per treatment. Performance data collected included ADG, DMI, and G:F. Finished steers were slaughtered on the same day. The following carcass attributes were collected; HCW, LMA, 12th rib fat, marbling score, KPH, and final yield grade. Beef strip loins were obtained from the carcasses, vacuum-packaged, and aged for 10 d at 4˚C. At d 10, steaks (~2.5 cm thick) were fabricated from each loin. Tenderness was analyzed using Warner-Bratzler shear force (WBSF). Retail shelf-life display was conducted over a 10 d period and two lights sources compared (fluorescent lighting or LED lighting) with muscle lightness (L*), muscle redness (a*), and muscle yellowness (b*) color scores recorded. Body weight gains, ADG, DMI, and G:F were not different (P > 0.14) among treatments. Additionally, carcass traits of HCW, LMA, 12th rib fat thickness, marbling score, final yield grades, and WBSF were not different (P > 0.26) among treatments. Shelf life evaluations showed that loin steak lightness (L* ; P > 0.70), redness (a* ; P > 0.62), and yellowness (b* ; P > 0.86) were not different among treatments. Light source did not impact (P > 0.96) L*, a*, or b* color scores. The cost of producing a kg of gain was not different between treatments. Feeding higher forage content during finishing of beef steers appears to have no effect on performance, meat quality or production costs.
Keywords: steers, feedlot, forage level