The objective was to determine the effects of substituting barley grain with short-season, high-moisture shelled corn, and barley grain and barley silage with snaplage on ruminal fermentation and the site and extent of digestion in beef cattle fed finishing diets. Six ruminally and duodenally cannulated heifers (420 ± 16.4 kg BW) were fed a barley grain and silage finishing diet (BG), a diet where half of the barley grain was replaced with high-moisture shelled corn (HC), or a diet where the barley silage and a portion of grain was replaced with snaplage (SN) in a replicated 3 × 3 Latin square design. While dry matter and starch intake were unaffected, feeding SN resulted in greater (P = 0.02) ruminal but not total tract starch digestibility than BG. Ruminal pH did not differ between HC and BG , but SN reduced (P = 0.02) minimum ruminal pH relative to BG. Feeding BG increased (P = 0.04) ruminal ammonia concentrations over HC. In conclusion, high-moisture shelled corn can partially replace barley grain with minimal impact on nutrient digestibility or ruminal fermentation, but replacement of barley silage and some barley grain with snaplage may increase the risk of ruminal acidosis.

This study compared the nutrient composition, in vitro methane production, and dry matter (DM) and fiber disappearance of barley greenfeed (seed heads, SEED; leaves, BLEAF; and stems, STEM) and short-season high-moisture corn stover (cobs, COB; leaves and husks, CLEAF; and stalks, STALK) to wheat straw (STRAW). Each plant component was analyzed for DM and neutral detergent fiber corrected for organic matter (aNDFom). Plant components were incubated in in vitro batch cultures for 30 h during which total gas production and methane were measured. Incubation residues were analyzed for DM and aNDFom. The aNDFom (% of DM) was different (P< 0.01; SEM = 1.64) amongst treatments: COB (82.1) = STRAW (75.2) = STALK (72.8) = CLEAF (69.4) > STEM (52.5) = BLEAF (50.4) > SEED (39.1). The DM disappearance (% of DM) of barley components was the greatest (P< 0.01; SEM = 1.734; BLEAF = 60.98, STEM = 57.15, and SEED = 56.52), followed by CLEAF (48.15) and STALK (40.47), but STALK did not differ from the least digestible components of COB (37.21) and STRAW (35.82). Disappearance of aNDFom (% of aNDFom) was greatest (P< 0.01; SEM = 1.734) for BLEAF (63.27), then CLEAF (53.40) and SEED (45.65), but the other components (COB = 44.77, STALK = 44.17, STEM = 42.93, and STRAW = 42.57) were lowest and did not differ from SEED. A difference in methane production (mL/g of DM digested) was observed (P< 0.01; SEM = 1.392) in the following manner: COB (52.07) = STEM (51.04) = STRAW (47.88) = SEED (47.43) > BLEAF (40.83) = CLEAF (38.20) = STALK (36.89). These data provide fiber digestibility coefficients and methane production by plant components and confirms that fiber content is inversely related to DM digestibility for barley and corn components at grain harvest.