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Four experiments evaluated the use of a complete starter feed (RAMP; Cargill Corn Milling, Blair, NE) for grain adaptation. In Exp. 1, 229 yearling steers (397 ± 28.4 kg BW) were used to compare a traditional adaptation program (CON) with adapting cattle with RAMP in either a 1- (RAMP-1RS) or 2- (RAMP-2RS) ration system. From d 23 to slaughter, cattle were fed a common finishing diet. In Exp. 2, 390 yearling steers (341 ± 14 kg BW) were used to compare accelerated grain adaptation programs with RAMP with 2 control treatments where RAMP was blended with a finishing diet containing either 25 (CON25) or 47.5% (CON47) Sweet Bran (Cargill Corn Milling) in 4 steps fed over 24 d to adapt cattle. Rapid adaptation treatments involved feeding RAMP for 10 d followed by a blend of RAMP and a 47% Sweet Bran finishing diet to transition cattle with 3 blends fed for 1 d each (3-1d), 2 blends fed for 2 d each (2-2d), or 1 blend fed for 4 d (1-4d). From d 29 to slaughter, all cattle were fed a common finishing diet. In Exp. 3, 300 steer calves (292 ± 21 kg BW) were used to compare the CON47 and 1-4d adaptation programs with directly transitioning cattle from RAMP, which involved feeding RAMP for 10 d and then switching directly to F1 on d 11 (1-STEP). From d 29 until slaughter, F2 was fed to all cattle. In Exp. 4, 7 ruminally fistulated steers (482 ± 49 kg BW) were used in a 35-d trial to compare the CON47 and 1-STEP adaptation programs. Ruminal pH and intake data from the first 6 d of F1and first 6 d of F2 were used to compare adaptation systems. Adaptation with RAMP-1RS and RAMP-2RS increased ( < 0.01) G:F compared with cattle adapted using CON in Exp. 1. Feeding RAMP-1RS increased ADG ( = 0.03) compared with CON. Intakes were similar ( = 0.39) among treatments. Daily gain, DMI, G:F, and carcass traits were similar ( > 0.11) among treatments in Exp. 2. Daily gain, DMI, and G:F were not different ( > 0.20) among treatments on d 39 or over the entire feeding period in Exp. 3. When F1 or F2 was being fed, DMI was similar ( ≥ 0.40) for CON47 and 1-STEP in Exp. 4. When F1 or F2 was being fed, 1-STEP cattle had lower average ruminal pH ( ≤ 0.03) and greater time below a pH of 5.3 ( ≤ 0.03). Using RAMP for grain adaptation improved performance compared with traditional adaptation. Rapid adaptation with RAMP decreased pH, but no performance differences were observed between long and rapid RAMP adaptation programs. Therefore, cattle started on RAMP do not require extensive adaptation before feeding a finishing diet with Sweet Bran.

Data from 16 trials were compiled to calculate microbial CP (MCP) production and MP requirements of growing cattle on high-forage diets. All cattle were individually fed diets with 28% to 72% corn cobs in addition to either alfalfa, corn silage, or sorghum silage at 18% to 60% of the diet (DM basis). The remainder of the diet consisted of protein supplement. Source of protein within the supplement varied and included urea, blood meal, corn gluten meal, dry distillers grains, feather meal, meat and bone meal, poultry by-product meal, soybean meal, and wet distillers grains. All trials included a urea-only treatment. Intake of all cattle within an experiment was held constant, as a percentage of BW, established by the urea-supplemented group. In each trial the base diet (forage and urea supplement) was MP deficient. Treatments consisted of increasing amounts of test protein replacing the urea supplement. As protein in the diet increased, ADG plateaued. Among experiments, ADG ranged from 0.11 to 0.73 kg. Three methods of calculating microbial efficiency were used to determine MP supply. Gain was then regressed against calculated MP supply to determine MP requirement for maintenance and gain. Method 1 (based on a constant 13% microbial efficiency as used by the beef NRC model) predicted an MP maintenance requirement of 3.8 g/kg BW and 385 g MP/kg gain. Method 2 calculated microbial efficiency using low-quality forage diets and predicted MP requirements of 3.2 g/kg BW for maintenance and 448 g/kg for gain. Method 3 (based on an equation predicting MCP yield from TDN intake, proposed by the Beef Cattle Nutrient Requirements Model [BCNRM]) predicted MP requirements of 3.1 g/kg BW for maintenance and 342 g/kg for gain. The factorial method of calculating MP maintenance requirements accounts for scurf, endogenous urinary, and metabolic fecal protein losses and averaged 4.2 g/kg BW. Cattle performance data demonstrate formulating diets to meet the beef NRC model recommended MP maintenance requirement (3.8 g/kg S) works well when using 13% microbial efficiency. Therefore, a change in how microbial efficiency is calculated necessitates a change in the proposed MP maintenance requirement to not oversupply or undersupply RUP. Using the 2016 BCNRM to predict MCP production and formulate diets to meet MP requirements also requires changing the MP maintenance requirement to 3.1 g/kg BW.

Two trials evaluated adapting cattle to a finishing diet using wet corn gluten feed compared with traditional methods using forage. A 33-d grain adaptation metabolism trial (Exp. 1) compared decreasing wet corn gluten feed (Sweet Bran; Corn Milling unit, Cargill Corn Milling, Blair, NE) while increasing corn inclusion (SB) and a traditional grain adaptation system decreasing alfalfa hay while increasing corn with no Sweet Bran inclusion (CON). Ruminal pH, intake characteristics, and 24-h in situ digestibility were evaluated using 8 ruminally fistulated steers (291 kg BW [SD 19]). Steers (4/treatment) were adapted to finishing diets across 4 periods consisting of 5, 7, 7, and 7 d and then fed a finishing diet for 7 d. No period × adaptation diet interactions were observed ( ≥ 0.12). Average ruminal pH decreased ( < 0.01) whereas time and area below a pH of 5.6 increased ( ≤ 0.02) for the SB adaptation system compared with the CON adaptation system. Cattle adapted using SB had greater DMI than cattle adapted using CON ( < 0.01). As steers were adapted to finishing diets, DMI increased ( = 0.01), average ruminal pH decreased ( = 0.05), and time and area below a pH of 5.6 increased ( ≤ 0.04) for both treatments. Ruminal pH for CON steers decreased from 6.59 to 6.12 across periods as corn replaced alfalfa hay whereas ruminal pH decreased from 6.00 to 5.79 for SB steers. Steers adapted using SB had greater ( ≤ 0.05) in situ digestion of adaptation diets than steers adapted using CON for adaptation periods 3, 4, and 5. The SB diets were more digestible than the CON diets when incubated in either CON- or SB-fed steers for adaptation periods 1 and 2 ( < 0.01). Experiment 2 used 240 finishing steers (273 kg BW [SD 14]) to determine performance impacts of using Sweet Bran instead of forage to adapt cattle to finishing diets. Steers were fed either decreasing Sweet Bran inclusion while increasing corn (SB) or decreasing alfalfa hay inclusion while increasing corn (CON). Treatments were applied only during grain adaptation (26 d) and all steers were finished on a common diet containing 35% Sweet Bran for an additional 147 d. Steers adapted using SB had greater ( ≤ 0.01) final BW, ADG, G:F, and HCW compared with steers adapted using CON, even though treatments differed only the first 26 d. Grain adaptation treatment had no effect ( ≥ 0.13) on carcass quality. These results indicate that Sweet Bran can be used to adapt cattle to finishing diets instead of forage and improves ADG and G:F while decreasing the forage needs of feedlots.

Expansion of the biodiesel industry has increased the crude glycerin (CG) supply. Crude glycerin has the potential of replacing corn in ruminant diets because the glycerol can be converted to glucose in the liver of ruminants, providing energy for cellular metabolism. The objective was to evaluate the effects of CG with urea, soybean meal, cottonseed meal, and corn gluten feed, respectively, on intake, digestibility, microbial protein yield, and efficiency of N utilization. Five Nellore bulls (initial BW of 448 kg [SD 14]) grazing tropical pasture were used in a 5 × 5 Latin square design. The supplements were control (no supplementation; only free-choice mineral mixture ad libitum), CG with urea (CG-Urea), CG with soybean meal, CG with cottonseed meal, and CG with corn gluten. Crude glycerin was used in all supplements to replace corn (15% of DM supplement). There were differences between CG-Urea and other supplements with regard to intake of DM (% of BW and total; < 0.01), OM ( < 0.01), CP ( < 0.01), and TDN ( < 0.01). The digestibility of CP was greater ( = 0.04) for animals supplemented with CG-Urea than for those fed other supplements. Animals supplemented with CG-Urea showed greater N intake ( < 0.01) and N ammonia ( = 0.04) than those supplemented with other treatments. Nitrogen retained (g/d) was not affected by protein source but was greater for cattle fed a protein supplement compared with cattle fed the control supplement ( < 0.01). Supplementing the animals with protein sources increased ( = 0.02) the daily production of rumen microbial nitrogen (g/d) compared with the control group. Microbial protein (g/d) was lesser for the control than for protein sources ( = 0.02). However, when expressed relative to TDN ( = 0.35) and CP ( = 0.82), there were no differences across treatments. Crude protein intake per digestible OM intake (g CP/kg digestible OM intake) was greater for animals fed protein sources compared with animals fed control supplements ( < 0.01). Based on nutrients intake and microbial protein yield, CG-Urea supplement has a greater feeding value compared with other protein sources. Crude glycerin, when used to replace corn in 15% of DM supplement, may be effective to improved N utilization and microbial protein yield in rumen of Nellore bulls grazing cv. Marandu.

Two experiments were conducted to determine the effects of roughage source and inclusion in diets containing wet distillers' grains plus solubles (WDGS) on finishing cattle performance and ruminal metabolism. In Exp. 1, 385 crossbred steer calves (initial BW = 346 kg [SD 29]) were used in a finishing trial. A control diet with no roughage inclusion was compared with 6 diets containing either alfalfa hay (ALF), corn silage (CSIL), or corn stalks (CSTK) at 2 inclusions as a 3 × 2 factorial. Alfalfa hay was included at 4 (low) or 8% (standard) of diet DM. Diets containing CSIL or CSTK were formulated to provide total dietary NDF equal to the low and standard ALF inclusion diets. The final diets contained 6.13 and 12.26% CSIL or 3.04 and 6.08% CSTK (DM basis). All diets contained 30% WDGS and a 1:1 mixture of dry-rolled and high-moisture corn (DM basis). Cattle fed no roughage had reduced ( < 0.01) DMI and tended ( ≤ 0.10) to have the lowest final BW and ADG compared with cattle fed roughage. There were no differences ( ≥ 0.11) in DMI, ADG, or G:F due to roughage source. Cattle fed a standard inclusion of roughage had greater ( ≤ 0.04) DMI and ADG compared with cattle fed diets with low inclusion, regardless of roughage source. Feed efficiency tended to be different among treatments ( = 0.09), with cattle fed no roughage having greater G:F than all treatments ( ≤ 0.06) except cattle fed the low level of CSTK, which had a similar G:F ( = 0.48). Feed efficiency was not affected by source of roughage ( = 0.23) or inclusion of roughage ( = 0.49). In Exp. 2, 6 ruminally fistulated steers (347 kg BW [SD 25]) were used in a 6 × 6 Latin square design. Treatments were arranged as a 2 × 3 factorial with ALF or CSTK included at zero, low, or standard levels similar to Exp. 1. Apparent total tract digestibility (%) of DM, OM, and NDF decreased linearly ( ≤ 0.07) due to increasing roughage inclusion. Average, maximum, and minimum ruminal pH increased linearly ( ≤ 0.09) as roughage inclusion was increased. Based on the results of this study, low levels of CSTK improved cattle performance relative to low inclusions of ALF or CSIL. Diets with standard inclusions of ALF, CSIL, or CSTK had similar performance. Roughage sources can be exchanged to provide equal NDF in finishing diets containing 30% WDGS without negatively impacting finishing cattle. Based on ADG, eliminating roughages when 30% WDGS was included in finishing diets was not beneficial.

Two experiments evaluated the effects of condensed distillers solubles (CDS) on performance and carcass characteristics of finishing beef cattle. In Exp. 1, 250 crossbred steers (initial BW = 355 ± 18 kg) were fed 0, 9, 18, 27, or 36% CDS (DM basis) which replaced a portion of urea and a 1:1 ratio of dry-rolled corn (DRC) and high-moisture corn (HMC). Steers were divided into 3 BW blocks and were assigned randomly to 25 pens. Dietary fat increased from 3.7 to 9.4% as CDS inclusion increased from 0 to 36%. Intake decreased linearly ( < 0.01) as CDS increased. A quadratic response was observed for ADG ( = 0.01) and G:F ( < 0.01) with maximum gain calculated at 20.8% CDS and maximum G:F at 32.5% CDS inclusion, which was 12% more efficient than those fed 0% CDS. Experiment 2 was designed as a 2 × 4 factorial using 400 crossbred steers (initial BW = 339 ± 15 kg) evaluating 0, 7, 14, or 21% CDS (DM basis) in 2 base byproduct diets containing either 20% modified distillers grains plus solubles (MDGS) or 20% Synergy (a blend of wet corn gluten feed and MDGS). Steers were divided into 2 BW blocks and were assigned randomly to 40 pens. A tendency for a base diet × CDS inclusion interaction was observed for ADG, HCW, and final BW ( < 0.10). Gain increased linearly ( = 0.01) and tended to increase quadratically ( = 0.09) in MDGS diets, with maximum calculated ADG at 16% CDS inclusion. Inclusion of CDS had no effect on ADG in Synergy-based diets. Increasing CDS resulted in a linear increase in G:F ( < 0.01) regardless of basal diet. Condensed distillers solubles may be included in the diet at greater than 30% (DM basis) without other byproducts and improve animal performance. Likewise, CDS can be fed in combination with other byproduct feeds but with less improvement in performance.

Two studies were conducted to optimize use of alkaline-treated corn stover and wheat straw and distillers grains as partial corn replacements. In Exp. 1, a finishing experiment used 30 pens (12 steers/pen) of calf-fed steers (initial BW = 374 ± 23.9 kg) with a 2 × 2 + 1 factorial arrangement of treatments with 6 replications per treatment. Factors were grind size, where corn stover was processed through a 2.54- or 7.62-cm screen, and chemical treatment (corn stover either fed in native, non-treated form [NT; 93.4% DM] or alkaline treated [AT; 5% CaO hydrated to 50% DM]). No interactions (P ≥ 0.38) were noted between grind size and chemical treatment. Feeding AT compared with NT improved (P ≤ 0.02) final BW, ADG, and G:F. Reducing grind size improved (P ≤ 0.01) ADG and G:F, and no interaction with chemical treatment was observed. Steers fed AT had similar DMI, ADG, G:F, and carcass characteristics compared with a 5% roughage control that contained 15 percentage units (DM basis) more corn. In Exp. 2, 60 individually fed steers (initial BW = 402 ± 61.4 kg) were randomly assigned to 10 diets. Six treatments evaluated 10, 25, or 40% dry-rolled corn (DRC), which was replaced with either a 2:1 or 3:1 ratio (DM basis) of modified distillers grains plus solubles (MDGS) and treated corn stover analyzed as a 2 × 3 factorial. An additional 3 treatments were added where a 3:1 ratio of MDGS:straw were compared with a 3:1 ratio of MDGS:stover. As DRC increased, G:F (P = 0.06) quadratically increased for 3:1 MDGS:stover diets. Increasing DRC increased (P = 0.07) G:F in treated stover diets, regardless of ratio. Increasing DRC increased (P = 0.10) ADG for 3:1 ratios for both straw and stover. Reducing grind size, feeding a maximum of 20% treated crop residue, and maintaining at least 25% corn in the diet are strategies for optimizing cattle performance when replacing dry-rolled and high-moisture corn with treated crop residues and distillers grains.

Increased corn prices over the past decade have altered land use away from traditional forage in favor of corn. Accordingly, beef and dairy producers have had to adopt nontraditional forage resources into their production systems, many of which have become available as a result of increased corn production. Corn residues have become more available due to increases in corn hectares and yield. The individual plant components (i.e., husk, leaf, and stem) vary in fiber digestibility (NDF digestibility estimates = 40.5, 31.4, and 0.6% ± 0.8 for husk, leaf, and stalk, respectively). Stocking cattle to consume 3.6 kg forage/25.5 kg of grain allows cattle to graze selectively; selection of husks and leaves improves cattle performance. Byproducts of the wet and dry milling industries can be supplemented to calves grazing corn residues to provide protein and energy. Optimal gains were observed when these byproducts were supplemented at approximately 2.5 kg/d to 250-kg growing calves. Gestating beef cows do not require supplemental inputs when grazing corn residue, if stocked appropriately. Alkaline treatment of crop residues improves their feeding value. Concentrations of up to 20% harvested corn residue treated with calcium oxide can be included in finishing diets with an average of 1.3% reduction in G:F when diets contain 40% wet or modified distillers grains. Conversely, when untreated corn residues are included in similar finishing diets, G:F is reduced by 13.4%. Calcium oxide-treated residues included in beef growing diets increases DMI and ADG without significant improvements in G:F. Calcium oxide treatment of corn residues has been evaluated in dairy diets by replacing corn or corn silage with variable results. Efficient use of nontraditional fiber sources, such as corn milling byproducts and corn residue, are critical to the future viability of ruminant animal production.

The objectives of this study were to evaluate the effect of dried distillers grains with solubles (DDGS) on ruminal biohydrogenation and duodenal flow of fatty acids, and to evaluate effects on the ruminal and duodenal microbial community using Roche 454 pyro-sequencing. Three crossbred steers (average BW 780 ± 137 kg) fitted with ruminal and duodenal cannulae were used in a 3-diet, 6-period crossover design. Animals were housed in individual free stalls and fed twice daily at 0700 and 1900 h. Diets (DM basis) were 1) CONTROL, 19.5% corn bran, 20% sorghum silage, 60% brome hay, 0.5% trace minerals, and 0.25% urea, but no DDGS; 2) LOW DDGS, inclusion of 9.75% DDGS replacing equal percentage of corn bran; 3) HIGH DDGS, inclusion of 19.5% DDGS completely replacing corn bran. Feed ingredients and duodenal digesta samples were analyzed for fatty acid composition. The DNA was extracted from isolated mixed ruminal bacterial samples and from intestinal digesta samples. The V1-V3 region of the 16S rRNA gene was sequenced, and bacterial phylogenetic analysis was conducted. Data were analyzed using the MIXED procedure of SAS. Biohydrogenation of C18:1 increased (P < 0.01) with DDGS inclusion; means were 68.3, 75.6, and 79.3 ± 4.3% for CONTROL, LOW DDGS, and HIGH DDGS, respectively. In the same order, means of biohydrogenation of C18:2 (P < 0.05) were 84.1, 91.5, and 93.3 ± 3.4%. Duodenal flow of total fatty acids increased (P < 0.01) with DDGS inclusion; means were 134, 168, and 223 ± 33 g/d for CONTROL, LOW DDGS, and HIGH DDGS, respectively. In the same order, means of C18:0 flow (P < 0.01) were 51, 86, and 121 ± 18 g/d. DDGS did not affect the predominant bacterial phyla in the gut, which were Bacteroidetes (P = 0.62) and Firmicutes (P = 0.71). However, the phylum Fibrobacteres decreased (P < 0.01) when DDGS was fed with means of 5.5, 6.0 and 3.7 ± 0.6% for CONTROL, LOW DDGS, and HIGH DDGS, respectively. Fibrobacteres were lower (P < 0.01) in isolated ruminal bacterial samples compared to duodenal digesta samples with means of 0.1 and 10.1 ± 0.6%, respectively. Overall, the inclusion of DDGS in diets increased ruminal biohydrogenation of C18:1 and C18:2, which increased duodenal flow of C18:0. In addition, the bacterial community of the rumen clustered separately from that of the duodenum suggesting different bacterial diversity between isolated ruminal bacteria and duodenal digesta.

Effects of S from wet or dry distillers grains with solubles (DGS) containing 0.82 or 1.16% S on animal growth performance, carcass characteristics, apparent total tract digestibility, and ruminal parameters were evaluated. In Exp. 1, crossbred beef steers (n = 120; 345 ± 34 kg BW) were individually fed ad libitum using Calan gates. Treatments were applied as a 2 × 2 × 3 + 1 factorial treatment arrangement with factors of DGS type (wet or dry), S content in DGS (0.82 or 1.16% DM basis), and DGS inclusion (20, 30, and 40%, DM basis), as well as a corn control diet (no DGS). In Exp. 2, ruminally cannulated crossbred beef steers (n = 6; 381 ± 31 kg BW) were assigned to 1 of 5 diets in a 5 × 6 unbalanced Latin Square design and fed ad libitum through five 14-d periods. A 2 × 2 + 1 factorial treatment arrangement was used with the factors of DGS type and S content in DGS (similar to Exp. 1). Inclusion of DGS was 40%, except for a MATCH diet containing wet 1.16% S DGS included at 31.4% (DM basis). Intake of DM decreased linearly (P < 0.01) and quadratically (P < 0.01) for steers fed wet and dry DGS that was 1.16% S, respectively. In addition, steers fed dry DGS consumed 9% more DM (P < 0.01) than those fed wet. Gain decreased linearly (P = 0.02) when wet 1.16% S DGS increased in the diet, representing a 12% drop in ADG between the Control and 40% DGS inclusion. A quadratic (P = 0.02) improvement in G:F was observed for steers fed wet DGS compared with dry, regardless of S content (P = 0.52). Feeding diets with wet 1.16% S DGS linearly decreased (P = 0.03) HCW. In Exp. 2, molar proportion of propionate declined (P = 0.01) 9% and A:P ratio tended (P = 0.13) to be greater when 1.16 compared with 0.82% S DGS was fed. Apparent total tract DMD was not affected (P > 0.16) and only subtle changes (P < 0.01) in ruminal pH parameters were observed. Greater (P = 0.02) ruminal H2S concentration for steers fed wet compared with dry DGS was observed, while 1.16% S DGS tended (P = 0.12) to produce greater ruminal H2S than 0.82% S. Sulfur in wet DGS appears to be more prone to be converted to ruminal H2S, because feeding 1.16% S as wet DGS had a greater impact on ADG, DMI, and ruminal H2S compared with dry DGS.

One metabolism trial and 2 finishing trials were conducted to evaluate the effects of adding corn bran and steep liquor (steep) in replacement of dry-rolled corn (DRC) on diet digestibility, cattle performance, and nutrient mass balance in open feedlot pens. The metabolism trial (Exp. 1) used 8 ruminally cannulated heifers in a 4 × 4 Latin square design and the 2 finishing trials used 128 steer calves fed for 167 d (Exp. 2) and 256 yearling steers fed for 126 d (Exp. 3). Dietary treatments for all trials included a DRC-based control (CON), 30% corn bran (30/0), 30% corn bran plus 15% steep (30/15), and 45% corn bran plus 15% steep (45/15), in which by-products replaced DRC and molasses in the diet (DM basis). Diets were not isonitrogenous or isoenergetic. In the metabolism trial, feeding the by-product diets produced greater rumen pH (5.95) than CON (5.76; P < 0.01). Total tract DM and OM digestibility were greater for heifers fed CON than the by-product diets (P < 0.01). Dry matter and NDF ruminal disappearance (%/h) of corn bran were numerically less for cattle fed the CON diet than the by-product diets (2.36 vs. 2.84 and 0.72 vs. 1.66, respectively). In the performance trials, steers fed the by-product diets consumed more DM (P = 0.06) and G:F was either similar for all diets in Exp. 2 (P = 0.56) or less for cattle fed 30/0 than the other diets in Exp. 3 (P = 0.05). Percent N loss was reduced in Exp. 2 by including corn bran in diets compared with CON (P < 0.01). However, in Exp. 3, no differences in percent N loss were detected among treatments (P = 0.16), but more N was removed in the manure from pens where steers were fed by-products (P = 0.01). Although steep did not improve diet digestibility, it was beneficial in maintaining cattle performance in the feedlot studies. Feeding corn bran in combination with steep increased manure N removed and N in compost, but decreased percent N lost during the winter months only.

Four experiments were conducted to evaluate RUP content and digestibility for smooth bromegrass, subirrigated meadow, upland native range, and warm-season grasses. Samples were collected from esophageally cannulated cows or ruminally cannulated steers. Forages were ruminally incubated in in situ bags for durations of time based on 75% of total mean retention time, which was based on IVDMD and rate of passage calculations. One-half of the bags were duodenally incubated and excreted in the feces, and NDIN was analyzed on all bags for RUP calculations. Crude protein was numerically greater early in the growing cycle for grasses compared with later as grasses matured (P ≤ 0.32). The RUP was 13.3%, 13.3%, and 19.7% of CP for smooth bromegrass, subirrigated meadow, and upland native range, respectively. These values tended to be lower early in the growth cycle and increased (linear P ≤ 0.13) as forages matured for warm-season grasses and subirrigated meadows. Because both CP and RUP content change throughout the growing season, expressing RUP as a percentage of DM gives more consistent averages compared with RUP as a percentage of CP. Coefficient of variation values for RUP as a percentage of DM averaged 0.21 over all 4 experiments compared with 0.26 for RUP as a percentage of CP. Average RUP as a percentage of DM was 2.03%, 1.53%, and 1.94% for smooth bromegrass, subirrigated meadow, and upland native range, respectively. Total tract indigestible protein (TTIDP) linearly increased with maturity for subirrigated meadow samples (P < 0.01). A quadratic response (P ≤ 0.06) for TTIDP was observed in smooth bromegrass and warm-season grass samples. Digestibility of RUP varied considerably, ranging from 25% to 60%. Subirrigated meadow, native range, and smooth bromegrass samples tended to have linear decreases (P ≤ 0.11) in RUP digestibility throughout the growing season. The amount of digested RUP was fairly consistent across experiments and averages for smooth bromegrass, subirrigated meadow, and upland native range were 0.92%, 0.64%, and 0.49% of DM, respectively. Warm-season grasses in Exp. 2 had greater RUP (4.31% of DM) and amount of RUP digested (2.26% of DM), possibly because of cattle selecting for leadplant that contains more CP than the grasses. Forages can vary in CP, RUP, TTIDP, and RUP digestibility depending on the forage type, year, and time within year, but RUP digestibility is likely less than what previous sources have reported.

Two experiments using 96 steers each were conducted to evaluate the effect of corn wet distillers grains plus solubles (WDGS) concentration on steer performance, N loss, and P mass balance. Feeding WDGS as an energy source instead of protein may increase N release into the environment but also the amount of N removed in the manure. Calves (BW = 294 ± 33 kg) were fed 167 d from November to May (WIN), and yearlings (BW = 373 ± 24 kg) were fed 133 d from June to October (SUM). Treatments consisted of 0, 15, and 30% dietary inclusion of WDGS (DM basis) replacing corn (CON, 15WDGS, 30WDGS, respectively). Basal diets consisted of high-moisture and dry-rolled corn fed at a 1:1 ratio, 7.5% alfalfa hay, 5% molasses, and 5% supplement (DM basis). The CON and 15WDGS diets were formulated to meet MP requirements, and 30WDGS exceeded MP requirements. Dry matter intake, ADG, and HCW increased linearly (P < 0.05) with WDGS concentration in the WIN, whereas DMI and ADG increased linearly (P < 0.10) in the SUM. Efficiency of BW gain was not different (P > 0.10) among treatments in either experiment. Nitrogen and P intake increased linearly (P < 0.01) with WDGS concentration in both experiments. Calculated retention of N and P increased linearly (P ≤ 0.05) with WDGS concentration in the WIN but not in the SUM (P > 0.10). Calculated excretion of N and P increased linearly (P < 0.01) with WDGS concentration in both experiments. Amount of N removed in the manure was not different (P = 0.26) among treatments in the WIN but increased linearly (P = 0.05) with WDGS concentration in the SUM. Amount of P and OM removed increased linearly (P ≤ 0.05) with WDGS concentration in both experiments. Amount of N lost (kg/steer) increased linearly (P < 0.05) with WDGS concentration in both experiments. Expressed as a percentage of N excretion, N volatilization rate (amount of N lost divided by N excretion) was not different (P > 0.30) among treatments and averaged 68.3 and 77.0 in the WIN and SUM, respectively. More N volatilized when WDGS were fed, but not all of the additional N excreted was volatilized. Regressing the amount of OM on the pen surface against manure N, 98% of the variability for manure N in the WIN and 92% in the SUM was accounted for. Feeding WDGS increased the total amount of N lost to volatilization; however, not all of the additional N excreted was lost because of an increase in the proportion of manure OM.

Phosphorus is an expensive nutrient to supplement, and excess may lead to manure P challenges. Therefore, minimizing dietary P to meet requirements is important. Two experiments were conducted to determine the P requirement of finishing cattle (Exp. 1) and to evaluate the effects of feeding different P concentrations on the quantity and route of P excretion (Exp. 2). In Exp. 1, 60 heifers (BW = 278 kg +/- 17 kg) were individually fed 1 of 5 dietary P concentrations (0.10, 0.17, 0.24, 0.31, or 0.38% P). Cattle performance, plasma P concentration, bone characteristics, and bone P concentration were used to determine the P requirement. Intake and ADG increased quadratically (P < 0.01) as dietary P increased. Plasma P in heifers receiving the 0.10% treatment was less (P < 0.01) than the other treatments and suggested that these heifers were experiencing a P deficiency. Total ash weight of the phalanx bones increased linearly (P < 0.01) as dietary P increased. In Exp. 2 using a 5 x 5 Latin square design, 5 different diets varying in P concentration (0.12, 0.27, 0.42, 0.30, and 0.36% P) were fed to steers to evaluate route and quantity of P excreted. Steers excreted little (1.78 g/d on average) P in the urine as a percentage of total P excretion. Steers on the 0.12% P diet excreted very little P in urine (0.50 g/d). Excretion of P was less (P < 0.05) for the cattle fed 0.12% P compared with all other treatments. Results from cattle performance, plasma P concentrations, and bone characteristics indicate that the heifers fed 0.10% P were experiencing a deficiency and the P requirement of finishing heifers is between 0.10 and 0.17% P. Dietary P concentrations of 0.10 to 0.17% P resulted in decreased P excretion. Supplementation of mineral P is unnecessary in grain-based feedlot diets because dietary P will greatly exceed the requirements (<0.17%).

Three experiments were conducted to evaluate the use of combinations of wet corn gluten feed (WCGF) and wet distillers grain plus solubles (WDGS) in dry-rolled and high-moisture corn-based finishing diets for beef cattle. In Exp. 1, 250 steers (BW = 343 +/- 13.5 kg) were fed 5 treatments consisting of a corn-based, control diet with 0% coproducts, and diets including 30% WCGF, 30% WDGS, 15% WCGF plus 15% WDGS, or 30% WCGF plus 30% WDGS. No associative effects resulted from feeding 15% WCGF plus 15% WDGS; DMI, ADG, and G:F were intermediate between steers fed WCGF or WDGS at 30% of diet DM. Feeding coproducts in combinations at 30 and 60% of diet DM increased ADG, G:F, and final BW (P < 0.05) compared with the corn-based diet. In Exp. 2, 280 yearling steers (BW = 370 +/- 0.45 kg) were used to evaluate feeding 0, 25, 50, or 75% coproducts as a combination of 50% WCGF:50% WDGS (DM basis). Additional diets were fed containing decreased alfalfa hay at 5, 2.5, and 0% (DM basis) as coproduct blend inclusions increased at 25, 50, and 75% (DM basis), respectively. No interactions were observed between alfalfa hay and coproduct blend levels, and no effects on ADG or G:F (P > 0.21) were observed due to alfalfa hay. Intake, ADG, and G:F responded quadratically (P < 0.05) across coproduct levels, with the greatest ADG and G:F at 25 and 50% blend, and similar ADG and G:F for the 0 and 75% blend levels. In Exp. 3, 504 steers (BW = 376 +/- 16 kg) were fed to evaluate 0, 10, 15, 20, 25, and 30% (DM basis) WDGS in diets containing 30% WCGF (DM basis) as well as a control diet with no coproducts. The inclusion of 30% WCGF in the diets increased DMI, ADG, and G:F (P < 0.05) when compared with control. Response to inclusion level of WDGS tended to be quadratic for DMI (P = 0.12), quadratic for ADG (P = 0.05), and no effect for G:F (P = 0.96). Greatest ADG was achieved with 15 to 20% WDGS inclusion in diets containing 30% WCGF. The use of combinations of WCGF and WDGS in finishing diets resulted in similar or improved steer performance compared with corn, suggesting replacement of corn with coproduct combinations up to 75% diet DM is possible if a roughage source is fed.

A finishing trial and a digestion trial were conducted to evaluate the effects of corn hybrid and processing method on nutrient digestibility, finishing performance, and carcass characteristics. A 2 x 5 factorial arrangement of treatments was used for both trials. Factors included 2 processing methods, dry-rolled (DRC) or high-moisture (HMC), and 5 commercially available corn hybrids. The finishing trial (Exp. 1) utilized 475 yearling steers (379 +/- 15 kg initial BW), stratified by BW into 2 blocks then assigned randomly to 1 of 60 pens (8 steers/pen). Treatments were assigned randomly to pens with 6 pens/treatment. Diets consisted of 67.5% corn (each hybrid processed as DRC or HMC), 20% wet corn gluten feed, 7.5% alfalfa hay, and 5% supplement. The digestion trial (Exp. 2) used 2 ruminally and duodenally fistulated Holstein steers (560 kg of BW) and the mobile bag technique. Bags were ruminally incubated for 22 h. For total tract digestibility, bags were subjected to a simulated abomasal pepsin digestion, inserted into the duodenum, and collected in the feces. No significant interactions between corn hybrid and processing method were observed in Exp. 1; therefore, only main effects are presented. Feeding HMC decreased (P < 0.01) DMI and increased (P < 0.01) G:F compared with cattle fed DRC. Hybrid tended to affect (P = 0.12) G:F, but did not affect (P > 0.36) any other variable. For Exp. 2, feeding HMC increased (P < 0.01) DM and starch digestibility compared with DRC, but to varying degrees depending on the hybrid. Correlating the results of the 2 trials across processing methods, strong relationships were observed between G:F and postruminal starch digestibility (r = 0.84) and total-tract starch digestibility (r = 0.73). When evaluated within processing method, these relationships weakened and were not significant. The results of these trials indicate that processing method had a larger effect on performance and digestibility than hybrid, and no interaction was observed between processing method and hybrid, suggesting hybrid effects were consistent across processing methods.

Three experiments evaluated the lipids in distillers grains plus solubles compared with corn or other sources of lipid in finishing diets. Experiment 1 utilized 60 individually fed yearling heifers (349 +/- 34 kg of BW) fed treatments consisting of 0, 20, or 40% (DM basis) wet distillers grains plus solubles (WDGS), or 0, 2.5, or 5.0% (DM basis) corn oil in a finishing diet based on high-moisture corn (HMC) and dry-rolled corn. Cattle fed 20 and 40% WDGS had greater (P < 0.10) G:F than cattle fed 0% WDGS. Cattle fed the 5.0% corn oil had less overall performance than cattle fed the other diets. Results from Exp. 1 indicated that adding fat from WDGS improves performance, whereas supplementing 5.0% corn oil depressed G:F, suggesting that the fat within WDGS is different than corn oil. Experiment 2 used 234 yearling steers (352 +/- 16 kg of BW) fed 1 of 5 treatments consisting of 20 or 40% (DM basis) dry distillers grains plus solubles, 1.3 or 2.6% (DM basis) tallow, or HMC. All diets contained 20% (DM basis) wet corn gluten feed as a method of controlling acidosis. No differences between treatments for any performance variables were observed in Exp. 2. The dry distillers grains plus solubles may be similar to tallow and HMC in finishing diets containing 20% wet corn gluten feed. Experiment 3 used 5 Holstein steers equipped with ruminal and duodenal cannulas in a 5 x 5 Latin square design. Treatments were a 40% WDGS diet, 2 composites, one consisting of corn bran and corn gluten meal; and one consisting of corn bran, corn gluten meal, and corn oil; and 2 dry-rolled corn-based diets supplemented with corn oil or not. Cattle fed the WDGS diet had numerically less rumen pH compared with cattle fed other treatments. Cattle fed WDGS had greater (P < 0.10) molar proportions of propionate, decreased (P < 0.10) acetate:propionate ratios, greater (P < 0.10) total tract fat digestion, and a greater (P < 0.10) proportion of unsaturated fatty acids reaching the duodenum than cattle fed other treatments. Therefore, the greater energy value of WDGS compared with corn may be due to more propionate production, greater fat digestibility, and more unsaturated fatty acids reaching the duodenum.

The objectives of this study were to expand the database and determine the intestinal digestibility of rumen undegradable protein (dRUP) of common dairy feeds and to determine the effects of feeding 37.9% wet corn gluten feed on these estimates. Two ruminally and duodenally fistulated steers were assigned randomly to a crossover design with 4-wk periods. The mobile bag technique was used to determine rumen undegradable protein (RUP), dRUP, total tract digestible protein, and total tract digestible dry matter of alfalfa hay, brome hay, alfalfa haylage, corn silage, whole cottonseed, soybean meal, soyhulls, ground corn, nonenzymatically browned soybean meal, and dried distillers grains. There was no consistent effect of diet on RUP, dRUP, total tract digestible protein, and total tract digestible dry matter. The RUP (% of crude protein) ranged from 5.97% for alfalfa haylage to 75.6% for nonenzymatically browned soybean meal. The dRUP ranged from 15.3% for alfalfa haylage to 96.5% for nonenzymatically browned soybean meal. The dRUP for alfalfa hay (33.9%), brome hay (39.1%), alfalfa haylage (15.5%), and corn silage (19.9%) were lower than National Research Council reported values. The higher dRUP of the nonenzymatically browned soybean meal is reflective of more total protein reaching the small intestine. The large range in dRUP was not reflected in total tract digestible protein (% of crude protein), with corn silage being the lowest at 85.2% and nonenzymatically browned soybean meal the highest at 97.9%. In this study, diet had little effect on intestinal digestibility of protein or dry matter.

Crossbred, spring-calving cows (yr 1, n = 136; yr 2, n = 113; yr 3, n = 113) were used in a 3-yr experiment to evaluate the influence of supplemental protein prepartum and grazing subirrigated meadow postpartum on pregnancy rates and calf feedlot performance. A 2 x 2 factorial arrangement of treatments was used in a switchback design. From December 1 to February 28, cows grazed dormant upland range in 8 pastures (32 +/- 2 ha each). The equivalent of 0.45 kg of supplement/cow per d (42% CP) was provided to half of the cows on a pasture basis 3 d/wk. For 30 d before the beginning of breeding (May 1 to May 31), half of the cows grazed a common subirrigated meadow (58 ha), and the remainder was fed grass hay in a drylot. Cow BW and BCS were monitored throughout the year, and steer calf performance was determined until slaughter. Feeding supplement prepartum improved (P = 0.01 to P < 0.001) BCS precalving (5.1 vs. 4.7) and prebreeding (5.1 vs. 4.9) and increased (P = 0.02) the percentage of live calves at weaning (98.5 vs. 93.6%) but did not affect (P = 0.46) pregnancy rate (93 vs. 90%). Calves born to dams fed supplement prepartum had similar (P = 0.29) birth weight (37 vs. 36 kg) but greater (P = 0.02) weaning weight (218 vs. 211 kg). However, steer feedlot DMI (8.53 vs. 8.48 kg), ADG (1.6 vs. 1.6 kg), and carcass weight (369 vs. 363 kg) were not affected (P = 0.23 to P = 0.89) by prepartum supplementation. Allowing cows to graze subirrigated meadow postpartum improved (P < 0.001) BCS prebreeding (5.2 vs. 4.9) but did not affect (P = 0.88) pregnancy rate (92 vs. 91%). Allowing cows to graze subirrigated meadow increased (P = 0.01) calf weaning weight (218 vs. 211 kg) but not (P = 0.62 to P = 0.91) feedlot DMI (8.4 vs. 8.3 kg), ADG (1.6 vs. 1.6 kg), or carcass weight (363 vs. 362 kg) of their steer calves. Increased percentage of live calves at weaning as a result of feeding supplemental protein increased net returns at weaning and after finishing in the feedlot. Net returns were increased by allowing cows to graze subirrigated meadow postpartum regardless of whether calves were marketed at weaning or after finishing in the feedlot.

An experiment was conducted with 36 primiparous and 40 multiparous Holstein cows to examine the effects of feeding wet corn gluten feed (WCGF) on 305-d milk production, dry matter (DM) intake, body condition score (BCS), and health. The experimental treatments included: 1) control--WCGF not fed (n = 27); 2) WCGF-L-cows received diets containing WCGF (38% DM basis) during lactation (n = 23); and 3) WCGF-DL--cows received diets containing WCGF (38% DM basis) during the dry period and lactation (n = 26). During the dry period, cows consuming WCGF were observed to have a significant gain in BCS (0.07 +/- 0.06) compared with a loss in BCS in cows fed the control diet (control = -0.11 +/- 0.06 and WCGF-L = -0.04 +/- 0.06). During lactation, there were no differences by treatment on BCS. Cows consuming WCGF during lactation consumed more feed compared with the control: 25.4, 23.8, and 21.2 +/- 0.76 kg/d for WCGF-L, WCGF-DL, and the control, respectively. Milk production was higher for cows consuming WCGF: 35.0, 34.7, and 31.1 +/- 2.1 kg/d for WCGF-L, WCGF-DL, and the control, respectively. No differences were found in either DM intake or actual milk yield between the WCGF-L and WCGF-DL treatments, indicating that prepartum diets did not influence lactational performance. The WCGF diets resulted in significant reductions in the concentration of milk fat (3.94, 3.74, and 4.15 +/- 0.08% for WCGF-L, WCGF-DL, and the control, respectively), but because total milk yield was increased, there were no differences in total milk fat yield. In addition, 3.5% of fat-corrected milk tended to be affected by diet: 38.9, 36.3, and 34.7 +/- 1.93 kg/d for WCGF-L, WCGF-DL, and the control, respectively. The increasing effect of DM intake and milk yield in cows consuming WCGF resulted in a similar efficiency of 3.5% fat-corrected milk production for all treatments, averaging 1.5 +/- 0.09. Total protein yields were significantly higher for cows consuming WCGF diets during lactation: 1.15, 1.10, 1.00 +/- 0.06 kg/d for WCGF-L, WCGF-DL, and the control, respectively. These results indicate that diets may be formulated to contain as much as 37.5% WCGF (DM basis).

Two experiments were conducted to determine the influence of chemical and physical corn kernel traits on digestibility and feedlot cattle performance. Seven commercially available corn hybrids representing a range in kernel traits were evaluated for a variety of chemical and physical traits that included test weight, 1,000-grain weight, kernel size, starch, CP, amylose, Stenvert Hardness tests (kernel hardness traits), tangential abrasive dehulling device loss, 12-h in vitro starch disappearance, and rate and extent of in situ DM disappearance. Differences among hybrids existed for all physical kernel traits measured. In Exp. 1, 224 steers in 28 pens were fed the same hybrids for 167 d in a completely randomized design. All diets were formulated to have 12.5% CP and contained 66% dry-rolled corn (DM basis). There were no differences (P >0.20) among corn hybrids for DMI, ADG, or carcass characteristics. However, efficiency of gain (G:F) was influenced by hybrid (P < 0.01) with a difference of 9.5% from the least to the most efficient. In Exp. 2, 7 ruminally cannulated heifers were used in a 7 x 7 Latin square design to determine the effects of these hybrids on nutrient digestibility, VFA concentrations, and ruminal pH. Total-tract OM and starch digestibilities were not different (P >0.15) among hybrids and averaged 77.9 and 95.1%, respectively. Differences (P < 0.05) among hybrids existed for ruminal propionate concentration and the acetate to propionate ratio. Kernel hardness traits correlated (P < 0.05) with G:F were 1,000-grain weight (r = -0.81), Stenvert time to grind (r = -0.83), and the proportion of Stenvert soft to coarse particle height (r = 0.83). Propionate concentration was not correlated (r = 0.45) with G:F but was correlated (P = 0.02) to the Stenvert time to grind (r = -0.83). Cattle fed dry-rolled corn hybrids with greater proportions of soft endosperm had greater concentrations of propionate and gained more efficiently than cattle fed hybrids with a harder endosperm. Selecting for these softer kernel traits may improve the efficiency of gain in feedlot cattle.

One-hundred ninety-two crossbred steers (initial BW = 351 +/- 11 kg) were used to determine the effects of removing alfalfa hay (AH) from dry-rolled corn-based diets containing wet corn gluten feed (WCGF) on animal performance and nutrient (N and OM) mass balance in open feedlot pens. Steers were stratified by weight and assigned randomly to 24 pens (2 x 3 factorial) and fed for 132 d from June to October 2002. Experimental diets contained either 0 or 35% WCGF and 0, 3.75, or 7.5% AH, and were formulated to be isonitrogenous. For efficiency of gain, an interaction occurred (P = 0.09) between AH and WCGF. Feed efficiencies of cattle fed 35% WCGF were improved 4.4% (P = 0.10) compared with efficiencies of cattle fed no WCGF at 0% AH; there was a marked improvement in ADG for cattle fed WCGF compared with no WCGF in diets with 0% AH. Within 35% WCGF diets, efficiency decreased as AH inclusion increased (P = 0.06). Efficiency was equal across AH levels when 0% WCGF was fed; however, ADG was decreased when AH was removed. Interactions between AH and WCGF were not detected for other performance or carcass criteria; therefore, main effects of AH and WCGF are discussed. Daily intake, ADG, and HCW increased linearly (P < 0.05) as dietary AH level increased. Feeding 35% WCGF also resulted in greater DMI (P < 0.01) and a tendency for greater ADG and HCW (P < or = 0.10) compared with steers fed no WCGF. Interactions between AH and WCGF were not observed for feedlot N mass balance. As level of AH increased across diets, N intake, N retention, and N excretion increased (P < 0.05). Steers fed 35% WCGF consumed and excreted more N (P < 0.01) than those fed no WCGF. More manure DM (P = 0.11), OM, and N (P < 0.01) were removed from pens housing steers fed 35% WCGF as well as greater OM and N recovery in finished compost. More N (kilogram/steer) was also lost to volatilization as a result of greater N excretion when WCGF was fed. Expressed as a percentage of N excretion, loss of N from pens housing steers fed 0 and 35% WCGF was not different, averaging nearly 80%. These data suggest that AH has less value when dry-rolled corn-based diets contain 35% WCGF and can be decreased from conventional levels. Furthermore, loss of N from open feedlot pens is high during the summer months, and feeding WCGF may not reduce N losses during these times of year.

A feeding trial evaluated the hypothesis that wet corn gluten feed would improve growth performance of cattle fed steam-flaked corn-based finishing diets and supply required degradable intake protein (DIP). The trial used 360 steer calves (initial BW = 288 +/- 11 kg) housed in 36 pens for 166 d in an incomplete 4 x 3 factorial arrangement of treatments. Pens of steers were assigned to treatments according to a completely randomized design (four replicates per treatment combination). Treatments were wet corn gluten feed (0, 20, 30, or 40% of dietary DM) and CP (13.0, 13.7, or 14.4% of dietary DM) via supplemental urea as DIP. The 0% wet corn gluten feed treatment included only the 13.7% CP diet, and the 40% wet corn gluten feed treatment included only the 13.7 and 14.4% CP diets. Final dietary DIP concentration was 9.0% for 0% wet corn gluten feed; 8.7, 9.5, and 10.2% for 20% wet corn gluten feed; 9.0, 9.7, and 10.3% DIP for 30% wet corn gluten feed; and 10.0 and 10.6% for 40% wet corn gluten feed. Hot carcass weight, ADG, DMI, and G:F responded quadratically (P < or = 0.05) to wet corn gluten feed. The 20, 30, and 40% wet corn gluten feed treatments increased ADG by 7, 6, and 3% and increased DMI by 4, 5, and 5%, respectively, relative to the 0% wet corn gluten feed treatment. Feed efficiency was 102, 101, and 98% of the 0% wet corn gluten feed treatment for 20, 30, and 40% wet corn gluten feed, respectively. Hot carcass weight, ADG, and G:F increased linearly (P < or = 0.05) in response to increased DIP. Nonlinear analysis for DIP over the combined 20 and 30% wet corn gluten feed treatments indicated a DIP requirement of 9.6% of DM for ADG and 9.2% of DM for G:F, corresponding to 14.6 and 14.3% CP for 20% wet corn gluten feed and 14.8 and 14.5% CP for 30% wet corn gluten feed, respectively. Fat thickness, marbling, LM area, and USDA yield grade were not affected (P = 0.12 to 0.99) by wet corn gluten feed or CP. These results show that the inclusion rate of wet corn gluten feed for maximizing ADG and G:F in steam-flaked corn-based finishing diets is approximately 20% of DM. The DIP requirement determined in this trial averaged 9.4% of DM.

One grazing and two feeding experiments were conducted to compare the feeding value of corn residue or corn grain from a genetically enhanced corn hybrid (corn rootworm-protected; event MON 863) with nontransgenic, commercially available, reference hybrids. In Exp. 1, two 13.7-ha fields, containing corn residues from either a genetically enhanced corn root-worm-protected hybrid (MON 863), or a near-isogenic, nontransgenic control hybrid (CON) were divided into four equal-sized paddocks. Sixty-four steer calves (262 +/- 15 kg) were stratified by BW and assigned randomly to paddock to achieve a stocking rate of 0.43 ha/steer for 60 d, with eight steers per paddock and 32 steers per hybrid. A protein supplement was fed at 0.45 kg/steer daily (DM basis) to ensure protein intake did not limit performance. Steer ADG did not differ (P = 0.30) between steers grazing the MON 863 (0.39 kg/d) and CON (0.34 kg/d) corn residues for 60 d. The four treatments for the feeding experiments (Exp. 2 and 3) included two separate reference hybrids, the near-isogenic control hybrid (CON), and the genetically enhanced hybrid (MON 863) resulting in two preplanned comparisons of CON vs. MON 863, and MON 863 vs. the average of the reference hybrids (REF). In Exp. 2, 200 crossbred yearling steers (365 +/- 19 kg) were fed in 20 pens, with five pens per corn hybrid. In Exp. 3, 196 crossbred yearling steers (457 +/- 33 kg) were fed in 28 pens, with seven pens per corn hybrid. In Exp. 2, DMI and G:F did not differ (P > 0.10) between MON 863 and CON; however, steers fed MON 863 had a greater (P = 0.04) ADG than steers fed CON. Gain efficiency was greater (P = 0.05) for MON 863 cattle than for REF cattle in Exp. 2, but other performance measurements (DMI and ADG) did not differ (P > 0.10) between MON 863 and REF. No differences (P > 0.10) were observed for performance (DMI, ADG, and G:F) between MON 863 and CON or MON 863 and REF in Exp. 3. In terms of carcass characteristics, no differences (P > 0.10) were observed between MON 863 and CON, as well as MON 863 and REF, for marbling score, LM area, or 12th rib fat thickness in both Exp. 2 and 3. Overall, performance was not negatively affected in the corn residue grazing or feedlot experiments, suggesting the corn rootworm-protected hybrid (event MON 863) is similar to conventional, nontransgenic corn grain and residues when utilized by beef cattle.

Two finishing trials were conducted to determine the effects of adding different types of corn bran, a component of corn gluten feed, on cattle performance. In Trial 1, 60 English crossbred yearling steers (283 +/- 6.7 kg) were used in a completely randomized design with four dietary treatments. Treatments were diets with no corn bran, dry corn bran (86% DM), wet corn bran (37% DM), and rehydrated dry bran (37% DM). Bran was fed at 40% of dietary DM. All finishing diets had (DM basis) 9% corn steep liquor with distillers solubles, 7.5% alfalfa hay, 3% tallow, and 5% supplement. Gain efficiency and ADG were greater (P < 0.01) for cattle fed no corn bran compared with all treatments containing corn bran; however, no differences were detected across corn bran types. In Trial 2, 340 English crossbred yearling steers (354 +/- 0.6 kg) were used in a randomized block design with treatments assigned based on a 2 x 4 + 2 factorial arrangement (four pens per treatment). One factor was the corn processing method used (dry-rolled corn, DRC; or steam-flaked corn, SFC). The other factor was corn bran type: dry (90% DM), wet (40% DM), or dry bran rehydrated to 40 or 60% DM. Bran was fed at 30% of dietary DM, replacing either DRC or SFC. Two control diets (DRC and SFC) were fed with no added bran. All finishing diets contained (DM basis) 10% corn steep liquor with distiller's solubles, 3.5% alfalfa hay, 3.5% sorghum silage, and 5% supplement. Corn bran type did not affect DMI (P = 0.61), ADG (P = 0.53), or G:F (P = 0.10). Dry matter intake was greater (P < 0.01) by steers fed bran compared with those fed no bran, and was greater by steers fed DRC than by steers fed SFC (P < 0.01). Interactions occurred (P < 0.01) between grain source and bran inclusion for ADG and G:F. The ADG by steers fed the SFC diet without bran was greater (P < 0.01) than by steers fed SFC diets with bran, whereas the ADG by steers fed DRC diets with or without bran was similar. Daily gain was 15.2% greater (P < 0.01) by steers fed SFC without bran than by steers fed DRC without bran. Gain efficiency was 16.9% greater (P < 0.01) for steers fed SFC without bran compared with steers fed DRC without bran. In DRC and SFC diets, feeding bran decreased (P < 0.01) G:F by 5.2 and 13.8%, respectively. The moisture content of corn bran had no effect on finishing steer performance, and drying corn bran did not affect its energy value in finishing cattle diets.

A finishing trial and a metabolism trial were conducted to determine the effect of supplemental metabolizable Lys level on finishing calf performance and to estimate the metabolizable Lys requirement of finishing calves. The finishing trial included 60 individually fed crossbred beef steer calves (237 kg; SD = 20 kg) supplemented with either incremental amounts of rumen-protected Lys and Met, or Met alone. Addition of Lys and Met improved gains and efficiencies (quadratic; P < .02) during the first 56 d. There was no response to supplemental Met alone, suggesting that supplemental Lys rather than Met was responsible for the improvement in performance. Using nonlinear analyses to compare gain relative to supplemental Lys intake, maximum gain was determined to be 2.10 kg/d, or .27 kg/d above the zero Lys control, at a supplemental Lys intake of 2.56 g/d. Steers supplemented with 3 and 4 g of Lys had a weight advantage over the control steers of 16 kg at 56 d and 32 kg at the end of the 161-d trial. However, there were no statistical responses to Lys or Met during any periods after 56 d. During a separate metabolism trial, four steers fed the control finishing diet were slaughtered, and abomasal contents were collected for amino acid analyses. The predicted (Level 1 NRC, 1996) metabolizable protein flow to the abomasum for the control diet was 715 g/d, and the predicted Lys flow was 37.9 g/d. A supplemental Lys intake of 2.56 g/d would increase the Lys flow to 40.5 g/d. Feedlot diets low in ruminal escape protein may be deficient in metabolizable Lys, especially early in the feeding period. The metabolizable Lys requirement of steer calves gaining 2.10 kg/d is estimated to be 40.5 g/d.

In situ, digestion, and growth studies were conducted to evaluate four meat and bone meals and six poultry by-product meals as sources of escape protein and to predict the first-limiting amino acid for growing calves. Escape protein values, determined by 12-h in situ incubation, ranged from 41.7 to 51.0% of CP for meat and bone meals; poultry by-product meals ranged from 32.0 to 39.8%. True protein digestion in the gastrointestinal tract of lambs differed among protein sources (P < .05), ranging from 79 to 95%. In each of three growth trials, 60 steers (258 +/- 24, 241 +/- 23, and 230 +/- 16 kg for Trials 1, 2, and 3, respectively) were supplemented with 4 of the 10 protein sources along with a urea supplement. Protein sources were fed at 30, 40, 50, and 60% of the supplemental CP, with urea supplying the remainder. Protein efficiency differed among treatments ( P < .10), ranging from .61 to 1.55. Amino acid composition was determined for each protein source, and the individual metabolizable amino acids were regressed on the protein efficiency values. Escape protein values were correlated (R2 = .75) with protein efficiency but had a negative slope. Metabolizable methionine was the only amino acid moderately correlated (R2 = .40, slope = 1.9) to protein efficiency, whereas other amino acids either correlated poorly or had negative slopes. These data indicate that the protein value of meat and bone meal and poultry by-product meal is limited by the amount of metabolizable methionine they contain.

Two trials evaluated the effect of a composite of feed ingredients formulated to be similar in nutrient composition to wet distillers byproducts on finishing performance of sheep and cattle. Trial 1 used 60 crossbred lambs (31 kg) assigned to one of four treatments: dry-rolled corn (DRC) control, dried distillers grains plus solubles, wet corn gluten feed (WCGF), and wet distillers grains composite (COMP1). The COMP1 consisted (DM basis) of 47.5 WCGF, 11.9% condensed distillers solubles, 30.5% corn gluten meal, 9.7% tallow, and .4% dicalcium phosphate and was fed at 40% of the diet DM. Lambs fed the COMP1 diet were 27% more efficient (P < .10) than lambs fed WCGF and 12% more efficient (P > .10) than lambs fed DRC. In Trial 2, 60 yearling crossbred steers (272 kg) were assigned to one of five treatments: DRC control, WCGF, wet distillers grains composite (COMP2), COMP2 minus tallow (-FAT), or COMP2 minus corn gluten meal (-CGM). the COMP2 consisted (DM basis) of 65.7% WCGF, 26.3% corn gluten meal, and 8.0% tallow and was fed at 40% of the diet DM. Steers fed COMP2 were more efficient (P < .10) than steers fed DRC or WCGF, and the steers fed -FAT and -CGM were intermediate to these three dietary treatments. A composite diet of WCGF, condensed distillers solubles, corn gluten meal, and tallow, formulated to be similar in nutrient composition to wet distillers byproducts, may improve feed efficiency compared with WCGF or DRC.

Two trials were conducted to determine the feeding value of sorghum distillers byproducts. Trial 1, a finishing trial, used 160 yearling steers (327 kg). Treatments consisted of dry-rolled corn (DRC) control, sorghum wet distillers grains (SWDG), sorghum wet distillers grains plus solubles (SWDGS), and sorghum dried distillers grain plus solubles (SDDGS). Distillers byproducts were fed at 40% of the diet DM. Cattle fed diets containing SWDG, SWDGS, or DRC were similar in efficiency of gain (P > .10); cattle fed SDDGS were less efficient (P < .10) than all other treatments. Sorghum wet distillers grains, SWDGS, and SDDGS contained 96, 102, and 80% relative NEg of corn, respectively. In Trial 2, 16 crossbred lambs (55 kg) were used to determine the digestibility of sorghum and corn distillers byproducts. Byproducts were fed at 80% of the diet DM and treatments consisted of corn wet distillers grains (CWDG), corn dried distillers grains plus solubles (CDDGS), SWDG, and SDDGS. Neutral detergent fiber digestibility was not different among treatments (P > .10). Corn wet distillers grains were higher in true nitrogen (P < .001), apparent nitrogen (P < .01), and organic matter digestibility (P < .05) than SWDG. Wet distillers byproducts were higher (P < .01) in apparent organic matter and nitrogen digestibility than dried distillers byproducts. Digestibility of distillers byproducts and subsequent energy values are influenced by type of grain used in the fermentation process and drying of the finished byproduct.