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The objective of these studies was to evaluate effects of increasing hybrid rye silage (HRS; harvested at boot stage in Study 1 and soft-dough in Study 2) inclusion as a replacement for barley silage (BS; harvested at soft-dough stage) on dry matter intake (DMI), ruminal fermentation, and growth performance of growing beef cattle. In Study 1, ruminally cannulated Hereford × Simmental heifers (n = 8) with an initial body weight (BW) of 519 ± 25.8 kg were used in a replicated 4 × 4 Latin square design with 28-d periods including 21 d of dietary adaptation and 7 d of data and sample collection to assess DMI and ruminal fermentation. Treatments included a control diet (DM basis) that contained 59.62% BS, 38.60% barley grain, and 1.78% of a vitamin and mineral supplement. Hybrid rye silage replaced 33, 67, and 100% of the BS on a DM basis. In Study 2, steers (n = 384; BW = 343 ± 20.2 kg) were stratified by BW and allocated to 32 pens in a randomized complete block design over 2 yr (4 pens/treatment/yr) to evaluate DMI, growth, and gain:feed (G:F). Steers were fed similar diets as Study 1 for 84 d in both years. In Study 1, increasing HRS linearly (P < 0.01) decreased DMI from 12.0 to 9.2 kg/d, and linearly increased (P = 0.02) water intake from 18.6 to 22.5 L/d. Increasing HRS linearly increased mean (P < 0.01) and minimum ruminal pH (P < 0.01). There was no effect of HRS inclusion on total shortchain fatty acid concentration (P = 0.46) in ruminal fluid, but the molar proportion of acetate linearly (P < 0.01) increased while propionate and butyrate linearly decreased (P < 0.01, and < 0.01, respectively) with increasing HRS inclusion. Moreover, increasing HRS inclusion linearly increased the molar proportions of isobutyrate and valerate (P = 0.06, and < 0.01, respectively) while caproate decreased linearly (P = 0.02). The ammonia-N concentration linearly increased with increasing HRS inclusion. In Study 2, DMI was 9.23, 9.10, 8.82, 8.08 kg/d (quadratic, P = 0.02) for diets containing 0, 33, 67, and 100% HRS, respectively. Likewise, ADG decreased (1.45, 1.36, 1.30, 1.08 kg/d; quadratic P < 0.01) as HRS inclusion increased and G:F ratio decreased linearly (P < 0.01) from 0.158 with 0% HRS to 0.134 g/kg when diets contained 100% HRS. Final BW was 462, 456, 450, and 432 kg when HRS was included at 0, 33, 67, and 100% of the silage, respectively (quadratic, P = 0.04). In conclusion, replacing BS with increasing proportions of HRS reduced DMI resulting in greater ruminal pH, altered molar proportions of individual SCFA, and reduced growth performance and G:F during the growing phase. [ABSTRACT FROM AUTHOR]

The objective of this study was to evaluate effects of increasing hybrid rye as a replacement for barley grain on feed intake, ruminal fermentation, and site of nutrient digestion in finishing cattle. Eight ruminally and duodenally cannulated Hereford-cross heifers (starting body weight = 514 ± 25.3 kg) were used in a replicated 4×4 Latin square design with 21-d periods including 15 d of dietary adaptation and 6 d of sample collection. Dietary treatments included a control diet with 10.0% hay, 85.2% barley grain, and 4.8% of a vitamin and mineral supplement on a dry matter (DM) basis. Hybrid rye grain replaced 33, 67, or 100% of the barley grain. Both cereal grains were dry rolled to 80% processing index. Feed, refusals, ruminal fluid, duodenal digesta, and fecal samples were collected. Data were analyzed using the MIXED procedure of SAS 9.4 (SAS Inst. Inc., Cary, NC). Increasing hybrid rye inclusion tended (P = 0.052) to linearly decrease DM intake. Additionally, increasing hybrid rye grain linearly decreased mean and minimum ruminal pH (P < 0.01) and increased the duration (P < 0.01) and area (P = 0.01) that pH was less than 5.5. There was no effect of hybrid rye inclusion on total short chain fatty acid, lactic acid concentrations, or osmolality. Likewise, the molar proportion of acetate and butyrate were not affected by hybrid rye inclusion. Propionate tended to linearly increase with increasing hybrid rye inclusion (P = 0.08). Increasing hybrid rye linearly increased NH3-N concentration (P = 0.03). Ruminal organic matter (OM) digestibility tended to linearly increase (P = 0.08) and ash-free neutral detergent fiber (aNDFom) digestibility linearly increased (P < 0.01) when increasing hybrid rye. There was no effect on ruminal starch digestibility (71.1 ± 5.12%). Intestinal digestibility of CP linearly decreased (P = 0.050), but there were no effects for other nutrients. Increasing hybrid rye linearly increased apparent total-tract DM, OM, and aNDFom digestibility (P < 0.05) but did not affect starch digestibility (97.4 ± 0.42%). Increasing the inclusion rate of hybrid rye grain at the expense of barley grain in finishing diets may decrease DMI and increase risk for ruminal acidosis; however, hybrid rye inclusion did not influence the site or extent of starch digestion and increased total tract digestibility of DM, OM, and aNDFom. [ABSTRACT FROM AUTHOR]

The objective of this study was to evaluate effects of increasing hybrid rye as a replacement for barley grain on feed intake, growth performance, and carcass characteristics for growing and finishing cattle. Commercial steers (n = 360) with an initial body weight (BW) of 348 ± 6.6 kg were stratified by BW and randomly assigned to 1 of 24 pens (15 steers/pen) for growing (n = 8; 65 d) phase and re-randomized for the finishing (n = 6; 118 d) phase. The control diet (BCON) for the growing phase included 60.2% barley grain, 28.0% barley silage, 7.0% corn silage, 3.4% oat hulls, with the remainder as mineral, vitamins, and urea. Hybrid rye was then included by replacing 50 or 100% of the barley grain (DM basis). Treatments for the finishing phase included a control containing 10% hay, 85.2% barley grain, with the remainder coming from mineral and vitamins (FCON). Hybrid rye grain was included by replacing 33 (33R), 67 (67R), and 100% (100R) of the barley grain (DM basis). Data were analyzed using the MIXED procedure for each phase independently with carcass data analyzed using the GLIMMIX procedure of SAS (SAS version 9.4; SAS Institute, Inc. Cary, NC). There was no effect of hybrid rye inclusion on DMI or G:F during the growing phase, but ADG increased quadratically (P = 0.04) with 50% rye having the greatest value. During finishing, DMI decreased linearly as hybrid rye inclusion increased (P = 0.03). Average daily gain was quadratically affected (P = 0.03) with an initial increase from FCON to 33% rye followed by a decrease with increasing rye grain inclusion, but G:F was not affected (0.148 kg BW/kg DMI). There was no effect of hybrid rye inclusion on hot carcass weight, dressing percentage, back-fat thickness, ribeye area, marbling score, and yield score. Increasing the inclusion of hybrid rye quadratically (P < 0.01) increased the proportion of severe liver abscesses with an average of 34.6% severely abscessed livers when hybrid rye grain was included compared with 11.1% for FCON. Partial replacement of barley grain with hybrid rye may improve ADG without affecting DMI or G:F during the growing phase. However, replacing barley grain in finishing diets with hybrid rye decreases DMI, increases risk for severe liver abscesses, but does not affect feed conversion suggesting hybrid rye could replace up to 33% of the barley grain. [ABSTRACT FROM AUTHOR]

This study evaluated the effect of processing method and severity of hybrid fall rye on dry matter intake (DMI), ruminal fermentation, and apparent total tract nutrient digestibility for beef cattle. Ruminally cannulated Simmental heifers (n = 8; 327±33 kg) were used in a replicated 4×4 Latin square (21-d periods) balanced for carry-over effects with a 2×2 factorial treatment. Tempered rye [water added to achieve 80% dry matter (DM)] was compared with dry-rolled rye. Roller gap width of 1.23-mm and 0.8-mm were used for coarse and finely processed rye, respectively. This resulted in processing index values of: 80.9% for dryrolled and coarse; 72.7% for dry-rolled and fine; 92.9% for tempered and coarse; and 88.2% for tempered and fine processed rye. Diets (DM basis) included hybrid rye grain (86%), barley silage (15%), mineral (6%), and dry distillers' grain plus solubles (3%). Feeding tempered rye increased (P< 0.01) DMI by 0.87 kg compared with dry-rolled rye, and feeding coarse rye increased (P=0.04) DMI by 0.33 kg compared with fine rye. Cattle fed dry-rolled and finely processed rye had greater (P< 0.04) area that pH was < 5.5 compared with tempered and coarse rye, respectively. Ruminal shortchain fatty acid concentrations and ammonia were not affected (P≥0.12). Feeding dry-rolled rye increased DM digestibility by 2.4% (P=0.02), and crude protein digestibility in 3.0% (P=0.01) compared with tempered rye. Starch digestibility was not affected by processing severity of dry-rolled rye, but increased from 92.8 to 95.9% for tempered rye with increasing severity (interaction, P=0.03). Rolling tempered rye at the same roller gap as dry-rolled rye decreases processing severity but may allow for a greater severity of processing without marked reductions in DMI and ruminal pH, while achieving similar total tract starch digestibility. When increasing processing severity (81 vs. 73%), dry-rolling hybrid rye may reduce DMI and ruminal pH. [ABSTRACT FROM AUTHOR]