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One hundred twenty individually fed steers (initial BW 283 kg ± 32) were utilized in an 84-d growing trial to evaluate the effects of increased metabolizable lysine from non-enzymatically browned soybean meal (SoyPass) in grass hay-based diets containing wet distillers grains plus solubles (WDGS). The treatments were arranged as a 2 × 3 factorial with two levels of protein supplement as 20% (low; DL20) or 35% (high; DL35) of dietary DM using WDGS as the basal protein source, and three increments of SoyPass (SP) replacing 0%, 30%, or 60% of the WDGS DM in the protein supplement yielding six dietary treatments. Average daily gain (ADG), dry matter intake (DMI), gain:feed (G:F), and plasma urea N (PUN) data were analyzed using the MIXED procedure of SAS as a 2 × 3 factorial. Animal was the experimental unit and fixed effects included body weight block, dietary inclusion of distillers grains (DL20, DL35), dietary inclusion of SoyPass (SP) (3 levels), and DL × SP inclusion interactions. Linear and quadratic interactions between DL and SP inclusion were analyzed using covariate regression. No interactions were detected for ADG between SP and DL ( P = 0.76). Additionally, SP had no effect on ADG ( P = 0.49). However, ADG was increased for steers consuming the DL35 diet compared to DL20 (1.13 vs. 0.86 kg/d, respectively; P < 0.01). A DL × SP interaction was detected for DMI ( P = 0.01). As SP replaced WDGS in the DL35 diet, DMI increased linearly from 8.10 to 8.93 kg/d ( P = 0.02). In the DL20 diet, DMI was not different as SP replaced WDGS ( P ≥ 0.11). Therefore, G:F tended to decrease linearly ( P = 0.06) as SP replaced WDGS in the DL35 diet, while no difference ( P ≥ 0.11) was detected in the DL20 diet, suggesting SP contained less energy than WDGS but did improve dietary lysine balance. Furthermore, plasma urea nitrogen (PUN) increased linearly as SP replaced WDGS in the DL20 diet ( P < 0.01) but was not affected by SP substitution in the DL35 diet ( P ≥ 0.19). When WDGS is fed at a low (20% DM) or high (35% DM) inclusion rate in a forage-based diet, replacing the distillers with a source of protected amino acids supplied through heat-treated soybean meal, did not improve performance. A more concentrated or energy-dense form of amino acids may be beneficial in forage-based growing cattle diets containing 20% distillers grains but is not needed in diets with 35% distillers grains., (© The Author(s) 2021. Published by Oxford University Press on behalf of the American Society of Animal Science.)

Two experiments were conducted to determine the effects of diet composition and time of urine spot sampling on estimates of urinary purine derivative (PD) excretion. In Exp. 1, 116 individually fed crossbred heifers (407 ± 32 kg) were arranged in a randomized block design (82 d). Treatments were arranged in a 2 × 3 factorial design, with two urine spot sample collection times (0700 and 1700 hours; AM and PM) and three diets: 85% steam-flaked corn (SFC); 85% SFC + 1.5% urea (UREA); or 25% SFC, 30% wet corn gluten feed, and 30% corn bran (BYPROD). In Exp. 2, six ruminally and duodenally fistulated steers (474 ± 37 kg) were arranged in a replicated 3 × 3 Latin square design, with dietary treatments identical to Exp. 1 (63 d). Treatment diets were selected to result in varied amounts of microbial crude protein (MCP) in order to evaluate the accuracy of using estimates of urinary PD excretion to predict MCP. Urine spot samples were collected at 0700, 1200, 1700, and 2200 hours. No urine collection time × diet interactions occurred ( P > 0.20) for any variable in either experiment. In Exp. 1, dry matter intake (DMI) was greatest with BYRPOD (10.40 kg/d) and lowest with SFC (7.90 kg/d; P < 0.05). Feed efficiencies were greatest for UREA (0.182) and least for SFC (0.141; P < 0.05). Urinary PD:creatinine (PD:C) ratio was greatest for BYPROD (1.25) and least for SFC (0.94; P < 0.05). Urine spot sampling time had a significant ( P < 0.05) impact on PD:C, 1.03 for AM and 1.22 for PM samples. In Exp. 2, DMI was greater ( P < 0.05) with BYPROD than with SFC and tended ( P = 0.07) to be greater with BYPROD than with UREA. Ruminal pH was greatest for BYPROD (5.94; P < 0.05). Flow of MCP was 636, 829, and 1,056 g/d for SFC, UREA, and BYPROD, with BYPROD being greater ( P < 0.05) than SFC and tending ( P = 0.06) to be greater than UREA. Urinary PD:C was greater ( P < 0.05) for BYPROD than SFC and tended ( P = 0.09) to be greater for UREA than SFC. Urinary PD:C increased linearly ( P < 0.05) with sampling time. Diets formulated to affect DMI and MCP flow resulted in differences in urinary PD excretion, and these results related well with MCP flow estimated from duodenal purines. Collecting spot samples of urine later in the day resulted in greater estimates of urinary PD excretion; purine and PD flows appear to increase with time after one morning feeding per day. This method is well suited to evaluating relative differences between treatments but should not be extrapolated to assume absolute values., (© The Author(s) 2020. Published by Oxford University Press on behalf of the American Society of Animal Science.)

To determine the effects of harvest method and ammoniation (3.7% of dry matter) on consumption and waste of baled corn residue, a 6 × 6 Latin square with a 3 × 2 factorial treatment structure was conducted. Six treatments consisted of either nonammoniated or ammoniated residue, harvested one of three ways: conventional rake and bale (CONV), New Holland Cornrower with two rows of stem chopped into the windrow with tailings (2ROW), or EZBale system (EZB) with a disengaged combine spreader and tailings dropped in a windrow. Open cows were grouped by body weight to produce a light block of two pens (448 kg ± 49.6) and a heavy block of four pens (649 kg ± 65.9). One bale was fed to each pen during each of six 7-d periods using round bale ring feeders with closed bottom panels. Residue falling around (waste) and remaining in (refusals) the feeder was collected. The daily nutrient intake was estimated as the difference between what was offered and what remained (waste plus refusals). Crude protein (CP) of residue offered did not differ ( P = 0.58) among harvest methods. The digestible organic matter (DOM) content of residue offered in 2ROW and EZB bales did not differ ( P = 0.86) and was greater ( P < 0.01) than CONV. Ammoniation increased ( P < 0.01) CP and DOM content of the residue offered. Total wasted and refused residue did not differ ( P = 0.12) between 2ROW (29%) and EZB (37%), while CONV (42%) was greater ( P = 0.02) than 2ROW but did not differ ( P = 0.34) from EZB. Ammoniation reduced ( P = 0.03) total waste and refusals from 41% to 32%. The nutrient content of both waste and refusals did not differ ( P ≥ 0.34) among harvest methods and, with the exception of CP, was not affected ( P ≥ 0.15) by ammoniation. The CP content of the waste was greater ( P = 0.02) and refusals tended to be greater ( P = 0.08) from ammoniated bales. The CP intake of 2ROW was greater ( P ≤ 0.02) than both EZB and CONV, while EZB tended ( P = 0.06) to be greater than CONV. The CP intake of all ammoniated residues was greater ( P < 0.01) than the nonammoniated residue. The DOM intake of nonammoniated 2ROW and EZB did not differ ( P = 0.61) but was greater than nonammoniated CONV ( P < 0.01). Ammoniation increased ( P < 0.01) DOM intake. Overall, ammoniation had much larger effects than harvest method, resulting in reduced waste and refusals and greater intake of DOM and CP. However, the combination of both ammoniation and selective harvest (2ROW or EZB) was needed to result in energy and protein intakes that would meet the needs of a mature cow in mid-gestation., (© The Author(s) 2020. Published by Oxford University Press on behalf of the American Society of Animal Science.)

Cow-calf production systems were analyzed using experimental data and historical economic information to model four separate production year using the 10-yr price period from 2005 to 2014. Treatments included two weaning dates, October (OCT) and December (DEC), and four winter nutritional treatments, grazing winter range with no supplement (WR0), low supplement (WR1), high supplement (WR2); or grazing corn residue with no supplement (CR) applied in a 2 × 4 factorial arrangement. Net returns at the December weaning date were greatest ( P < 0.05) for DEC systems where cows were fed the WR2 level ($151.14/cow) or CR ($140.17/cow), intermediate for cows fed the WR1 ($110.44/cow), and least for cows fed WR0 ($62.23/cow). Average net returns across winter nutrition treatments at the December weaning date were greater ( P < 0.01) for DEC systems ($115.99/cow) compared with OCT systems ($110.28/cow). Marketing October weaned calves in December increased net returns on average by $47.24/cow compared with October marketing. Retained and owned (RO) slaughter steer net returns sold on a hot carcass weight (HCW) basis were greatest ( P < 0.05) for CR systems ($190.62/cow) or WR2 ($188.13/cow), intermediate for WR1 ($132.67/cow) and least for the WR0 ($68.08/cow) treatment. In general, purchasing weaned calves (PC) and marketing them as finished steers either on a HCW basis or on a marketing grid were not profitable. The WR2 and the CR grazing regimes were more profitable than WR0 and WR1 regardless of market end point, primarily due to reduction in replacement and production loss costs., (© The Author(s) 2019. Published by Oxford University Press on behalf of the American Society of Animal Science.)

A 4-yr experiment examined how weaning date and prepartum nutrition affected productivity in a spring (March and April) calving system. Crossbred beef cows (479 ± 59 kg, n = 144) were used in a completely randomized design with a 2 × 4 factorial treatment arrangement: 1) cows were weaned in early October or early December; and 2) during late gestation cows were fed on a dry matter basis a 32% crude protein supplement at 0, 0.41, or 0.82 kg/cow/d on dormant upland range or grazed corn residue without supplement. Cow body condition score (BCS) was affected ( P ≤ 0.01) by treatment prior to parturition and breeding but was similar ( P > 0.27) among all treatments in October. Dams on a higher nutritional plane during winter treatment had greater ( P < 0.01) BCS and body weight (BW) prior to parturition and breeding. Subsequent pregnancy rates (88% to 97%) were not influenced ( P > 0.76) by weaning date, but tended ( P = 0.10) to be lower for cows grazing winter range without supplement. Calves born to dams grazing winter range without supplement had lower ( P < 0.01) BW in October and adjusted weaning BW. Pre-breeding BW of heifers weaned in December born to cows grazing winter range without supplement was lower ( P < 0.01) than contemporaries born to cows in all other treatment combinations. However, postweaning (0.48 kg/d) and postbreeding (0.42 kg/d) average daily gain, percentage cycling before breeding (33%), and pregnancy rate (81%) was similar ( P > 0.12). Within weaning date, steers born to cows grazing winter range without supplement had lower ( P < 0.05) hot carcass weight (HCW) than contemporaries born to cows grazing corn residue. Cows weaned in December had decreased BW and BCS but similar pregnancy rates as cows weaned in October. Weaning date and dam maternal nutrition had minimal impact on heifer progeny pregnancy rate. Steer progeny born to dams on a higher nutritional plane had similar HCW at slaughter when adjusted to equal fat thickness., (© The Author(s) 2019. Published by Oxford University Press on behalf of the American Society of Animal Science.)

Three experiments evaluated delaying corn silage harvest, silage concentration, and source of supplemental protein on performance and nutrient digestibility in growing and finishing diets. Experiment 1 used 180 crossbred yearling steers (body weight [BW] = 428; SD = 39 kg) to evaluate corn silage dry matter (DM) (37% or 43%) and replacing corn with silage (15% or 45% of diet DM) in finishing diets containing 40% modified distillers grains with solubles. Experiment 2 used 60 crossbred steers (BW = 271; SD = 32 kg) to evaluate corn silage harvest DM (37% or 43%) and response to rumen undegradable protein (RUP) supplementation (0.5%, 1.4%, 2.4%, 3.3%, or 4.2% of diet DM) in silage growing diets. Experiment 3 used 9 crossbred lambs (BW = 30.1; SD = 4.1 kg) to evaluate nutrient digestibility of 37% or 43% DM corn silage in silage growing diets fed ad libitum or restricted to 1.5% of BW. In experiment 1, as corn silage concentration increased from 15% to 45%, average daily gain (ADG) and gain-to-feed ratio (G:F) decreased ( P ≤ 0.04). Carcass-adjusted final BW and hot carcass weight (HCW) were lower ( P ≤ 0.04) for steers fed 45% corn silage compared to 15% when fed for equal days. As DM of corn silage was increased from 37% to 43%, no differences ( P ≥ 0.30) in dry matter intake (DMI), ADG, G:F, or HCW were observed. In experiment 2, as DM of corn silage increased from 37% to 43%, ADG and G:F decreased ( P ≤ 0.04). Increasing supplemental RUP in the diet increased ( P ≤ 0.05) ending BW, DMI, ADG, and G:F linearly as supplemental RUP increased from 0.5% to 4.2%. In experiment 3, there were no differences ( P ≥ 0.56) in DM digestibility and organic matter digestibility between silage harvest DM and intake level. Neutral detergent fiber (NDF) intake was reduced ( P < 0.01) for lambs fed the delayed harvest corn silage compared to earlier corn silage harvest. As silage harvest was delayed from 37% to 43% DM, NDF digestibility decreased ( P < 0.01) from 64.39% to 53.41%. Although increasing corn silage concentration in place of corn in finishing diets reduced ADG and G:F, delayed silage harvest did not affect performance of finishing cattle. Delayed silage harvest in growing cattle resulted in lower ADG and G:F, possibly due to increased starch or maturity leading to decreased NDF digestibility. The addition of RUP to silage-based, growing diets improves performance by supplying more metabolizable protein and suggests RUP of corn silage is limiting., (© The Author(s) 2019. Published by Oxford University Press on behalf of the American Society of Animal Science.)

The amount of rumen undegradable protein (RUP) in corn silage and the extent to which it is digested in the small intestine are uncertain. Three studies were conducted to determine RUP content of corn silage, and the effects of supplementing increasing concentrations of RUP on the growing performance of calves fed a corn silage diet. Experiments 1 and 2 used in situ methods to evaluate the RUP content of corn silage. In experiment 1, corn silages harvested at 37% or 42% dry matter (DM) were compared. In experiment 2, dry-rolled corn (89.4% DM) was reconstituted to 75%, 70%, 65%, and 50% DM and ensiled in mini-silos (2,265 cm 3 ) for 30, 90, 180, or 270 d to simulate the corn grain within corn silage, dry-rolled corn is more mature than corn grain harvested in corn silage. Experiment 3 used 60 steers (275 kg initial body weight, SD = 18) in an 83-d growing study to evaluate the effects of supplementing 0.4%, 1.7%, 3.0%, 4.2%, or 5.5% RUP (% of diet DM) on performance. In experiment 1, RUP as a % of DM was not different between the two corn silages ( P ≥ 0.12), averaging 0.59% for samples refluxed in a neutral detergent solution (NDS) and 1.8% for samples not refluxed in NDS. Dry matter digestibility (DMD) also did not differ ( P ≥ 0.19), averaging 67.4%. In experiment 2, as moisture content of the corn grain increased, DMD increased linearly ( P < 0.01) and RUP content decreased linearly ( P < 0.01). The DMD increased quadratically ( P = 0.02), whereas RUP content decreased linearly ( P < 0.01) as days of ensiling increased. In experiment 3, there were no differences in DM intake (DMI; P ≥ 0.33) among treatments for period 1 (d 1 to 37). However, average daily gain (ADG) and gain-to-feed ratio (G:F) both linearly increased ( P < 0.01) as RUP supplement inclusion increased. There were no differences in DMI ( P ≥ 0.16), ADG ( P ≥ 0.11), or G:F ( P ≥ 0.64) in period 2 (d 38 to 83). For the overall growing period (d 1 to 83), a linear increase was observed for ending body weight ( P = 0.01), ADG ( P < 0.01), and G:F ( P < 0.01) as RUP supplement inclusion increased from 0.4% to 5.5% of diet DM. The RUP content of corn silage is lower than previously reported. Data collected suggest the crude protein within corn silage is 13% RUP, and approximately 1/2 is digestible. The moisture content of corn silage at the time of harvest and the amount of time corn silage is stored continually impact protein availability. Supplementing growing calves fed corn silage with RUP will improve performance., (© The Author(s) 2019. Published by Oxford University Press on behalf of the American Society of Animal Science.)

To determine the effect of harvest method and ammoniation on both in vivo and in vitro digestibility of corn residue, six corn residue treatments consisting of three different harvest methods either with or without anhydrous ammonia chemical treatment (5.5% of dry matter [DM]) were evaluated. The harvest methods included conventional rake-and-bale (CONV) and New Holland Cornrower with eight rows (8ROW) or two rows (2ROW) of corn stalks chopped into the windrow containing the tailings (leaf, husk, and upper stem) from eight rows of harvested corn (ammoniated bales of each harvest method resulted in treatments COVAM, 8RAM, and 2RAM). Nine crossbred wether lambs (49.2 ± 0.5 kg BW) were fed 64.2% corn residue, 29.8% wet corn gluten feed, 3.3% smooth-bromegrass hay, and 2.8% mineral mix (DM basis) in a 9 × 6 Latin rectangle metabolism study with a 3 × 2 factorial treatment to measure total tract disappearance. Six 21-d periods consisted of 14-d adaptation and 7-d total fecal collection, and lambs were fed ad libitum (110% of the previous day's DM intake [DMI]) during days 1 to 12 and reduced to 95% of ad libitum intake for days 13 to 21. There was a harvest method by ammoniation interaction ( P < 0.01) for ad libitum DMI (days 7 to 11). Ammoniation increased ( P < 0.01) intake across all harvest methods, where 2RAM DMI was 4.1%, COVAM was 3.6%, and 8RAM was 3.1%, which were all different ( P < 0.01) from each other, but all untreated residues were consumed at 2.6% of BW ( P ≥ 0.92) regardless of harvest method. There were no interactions ( P > 0.34) between harvest method and ammoniation for any total tract or in vitro digestibility estimate. Harvest method affected ( P < 0.04) DM, neutral detergent fiber (NDF), and acid detergent fiber (ADF) digestibility, where 2ROW was greater than both CONV and 8ROW, which did not differ. The organic matter (OM) digestibility ( P = 0.12) and digestible energy (DE; P = 0.30) followed the same numerical trend. Both in vitro DM digestibility (IVDMD) and in vitro OM digestibility (IVOMD) of the residue were affected ( P < 0.01) by harvest method, with 2ROW being greater ( P < 0.01) than both CONV and 8ROW. For IVDMD, 8ROW was not ( P = 0.77) different from CONV, but 8ROW IVOMD was lower ( P = 0.03) than CONV. Ammoniation improved ( P < 0.01) DM, OM, NDF, and ADF digestibility of all harvest methods, resulting in a 26% increase ( P < 0.01) in DE due to ammoniation. Similar digestibility improvements were observed in vitro with ammoniation improving IVDMD and IVOMD by 23% and 20%, respectively. Both selective harvest methods and ammoniation can improve the feeding value of baled corn residue., (© The Author(s) 2019. Published by Oxford University Press on behalf of the American Society of Animal Science.)

A series of total urine collections were conducted to evaluate the effects of age, diet, gestation, and body condition score ( BCS ) on urinary creatinine ( UC ) and purine derivative ( PD ) excretion in heifers and cows. For each collection, urine was collected over a 5-d period and composited by animal within day. Daily samples were analyzed for UC and PD concentration and averaged over the 5-d period. All animals were fed in individual stanchions at 2.0% of body weight ( BW ). To evaluate the relationship between age and UC excretion, 21 animals ranging from 5 to 80 months of age were fed a forage-based diet supplemented with dried distillers grains (DDG). Creatinine excretion (mg/kg BW) was not correlated with age ( P = 0.37). To determine if diet alters UC, 11 heifers were sampled for two urine collection periods. In period 1, heifers were fed a forage-based diet supplemented with DDG. In period 2, heifers were fed a finishing diet (90% concentrate, 10% forage). Creatinine excretion (mg/kg BW) and PD:creatinine ( PD:C ) was greater ( P = 0.01) for heifers when fed the forage-based diet than when fed the concentrate-based diet. Eleven cows fed a forage-based diet supplemented with DDG were sampled to determine the effect of gestation on urinary metabolites. Gestation did not affect UC ( P = 0.42) or PD:C ( P = 0.30). To evaluate the relationship between 12th rib fat thickness and metabolite excretion, 40 heifers were fed a common finishing diet. There was no relationship between UC (mg/kg BW; P = 0.28) or PD:UC ( P = 0.47) and 12th rib fat thickness. To evaluate the relationship between BCS and UC, 11 cows were fed a forage diet supplemented with DDG. There was no relationship between BCS and UC (mg/kg BW; P = 0.99) or PD:C ( P = 0.84). To evaluate daily and diurnal variation in UC, nine heifers were fed a forage diet supplemented with DDG. Seven of the heifers were fed a finishing diet (90% concentrate, 10% forage) in a second period. Urine was collected every 2 h from 0600 to 1800 hours. When expressed as mg/kg BW, UC excretion was not different across animals fed the forage-based ( P = 0.40) or concentrate-based diet ( P = 0.18). Stepwise regression indicated that at least 3 d of collection were required to estimate UC. Time within day and day within period effects were observed ( P < 0.01) for UC from 2-h interval samples. The UC varies with type of diet and diurnal variation is present. Variation among animals is relatively small., (© The Author(s) 2019. Published by Oxford University Press on behalf of the American Society of Animal Science.)

Three experiments evaluated the effects of corn oil removal using centrifugation in ethanol plants, on animal performance and digestion characteristics by finishing cattle fed by-products. In Exp. 1, 225 crossbred steers (300 ± 9.1 kg) were utilized in a randomized block design with a 2 × 2 + 1 factorial arrangement of treatments. Factors consisted of oil concentration [de-oiled (DO) or full fat (FF)] and by-product type [condensed distillers solubles (CDS) or modified distillers grains plus solubles (MDGS)] compared to a corn-based control. Fat concentration was 6.0% for DO CDS, 21.1% for FF CDS, 9.2% for DO MDGS, and 11.8% for FF MDGS. No oil concentration by by-product type interactions (P ≥ 0.17) were observed. There were no differences in DMI, ADG, or G:F between DO and FF CDS (P ≥ 0.29) or DO and FF MDGS (P ≥ 0.58). No differences (P ≥ 0.25) due to oil concentration were observed for carcass characteristics. Experiment 2 was a 5 × 5 Latin Square digestion trial with treatments similar to Exp. 1. Fat concentration was 8.7% or 15.4% for DO or FF CDS and 9.2% or 12.3% for DO or FF MDGS. Intake and total tract digestibility of fat were greater (P ≤ 0.02) for FF CDS compared with DO CDS. Digestible energy (megacalorie per kilogram), adjusted for intake, was greater (P = 0.02) for steers fed FF CDS compared to DO CDS. Average ruminal pH for cattle fed FF MDGS was greater than DO MDGS (P = 0.06). In Exp. 3, 336 yearling, crossbred steers (352 ± 19 kg) were utilized in a randomized block design with a 2 × 3 + 1 factorial arrangement of treatments. Factors included oil concentration (DO or FF) and inclusion [35%, 50%, and 65% wet distillers grains plus solubles (WDGS)] along with a corn-based control. The fat concentrations of DO and FF WDGS were 7.9% and 12.4%, respectively. A linear interaction (P < 0.01) was observed for DMI, which produced different slopes for DO and FF WDGS. No linear or quadratic interactions were observed for BW, ADG, or G:F (P ≥ 0.31). For the main effect of oil concentration, there were no statistical differences (P > 0.19) for final BW, ADG, or G:F. No statistical differences were observed for all carcass traits (P ≥ 0.34). Corn oil removal via centrifugation had minimal impact on finishing performance suggesting that cattle fed DO by-products will have similar performance to cattle fed FF by-products in dry-rolled and high-moisture corn diets.

Feeding high levels (≥40% dry matter) of distillers grains may increase the risk for cattle to carry enterohemorrhagic Escherichia coli (EHEC) O157. The mechanism for the increased risk is not known nor whether non-O157 EHEC are similarly affected. Our objective was to test whether the fibre content or other components of modified distillers grains plus solubles (MDGS) affects the probability for cattle to carry EHEC serogroups of public health importance. A 2 × 2 plus 1 factorial treatment arrangement within a randomized block design was utilized. Within each of four blocks, 25 feedlot pens (n = 8 steers/pen) were assigned randomly to (i) corn-based control diet; (ii) 20% dry matter (DM) MDGS; (iii) 40% DM MDGS; (iv) corn bran added to corn-based diet to match fibre of 20% MDGS or (v) 40% MDGS. Rectoanal mucosa swabs (RAMS) were collected on day (d)0, d35, d70 and d105; hide swabs were collected on the last feeding day. Samples were tested for EHEC by a molecular screening assay. The effects of fibre source and fibre level on EHEC carriage were tested using multilevel logistic regression (generalized linear mixed models; α = 0.05). EHEC O45 RAMS detection was associated with fibre level, source and sampling day. EHEC O103 RAMS detection increased by feeding 40% MDGS but not the corresponding corn bran diet. Hide contamination by EHEC O45 or O103 was less likely in cattle fed MDGS compared to corn bran diets. EHEC O111 RAMS detection decreased by feeding 40% MDGS but not by feeding the corresponding corn bran diet. Detection of EHEC O157 or O145 was not associated with dietary factors. Feeding 40% MDGS increased the probability for carriage of some EHEC serogroups but decreased probability of others, which indicated that EHEC serogroups have different risk factors associated with feeding MDGS and little association with dietary fibre., (© 2017 Blackwell Verlag GmbH.)

Two experiments evaluated the effects of corn residue harvest method on animal performance and diet digestibility. Experiment 1 was designed as a 2 × 2 + 1 factorial arrangement of treatments using 60 individually fed crossbred steers (280 kg [SD 32] initial BW; = 12). Factors were the corn residue harvest method (high-stem and conventional) and supplemental RUP at 2 concentrations (0 and 3.3% diet DM). A third harvest method (low-stem) was also evaluated, but only in diets containing supplemental RUP at 3.3% diet DM because of limitations in the amount of available low-stem residue. Therefore, the 3 harvest methods were compared only in diets containing supplemental RUP. In Exp. 2, 9 crossbred wethers were blocked by BW (42.4 kg [SD 7] initial BW) and randomly assigned to diets containing corn residue harvested 1 of 3 ways (low-stem, high-stem, and conventional). In Exp. 1, steers fed the low-stem residue diet had greater ADG compared with the steers fed conventionally harvested corn residue ( = 0.03; 0.78 vs. 0.63 kg), whereas steers fed high-stem residue were intermediate ( > 0.17; 0.69 kg), not differing from either conventional or low-stem residues. Results from in vitro OM digestibility suggest that low-stem residue had the greatest ( < 0.01) amount of digestible OM compared with the other 2 residue harvest methods, which did not differ ( = 0.32; 55.0, 47.8, and 47.1% for low-stem, high-stem, and conventional residues, respectively). There were no differences in RUP content (40% of CP) and RUP digestibility (60%) among the 3 residues ( ≥ 0.35). No interactions were observed between harvest method and the addition of RUP ( ≥ 0.12). The addition of RUP tended to result in improved ADG (0.66 ± 0.07 vs. 0.58 ± 0.07 for supplemental RUP and no RUP, respectively; = 0.08) and G:F (0.116 ± 0.006 vs. 0.095 ± 0.020 for supplemental RUP and no RUP, respectively; = 0.02) compared with similar diets without the additional RUP. In Exp. 2, low-stem residue had greater DM and OM digestibility and DE ( < 0.01) than high-stem and conventional residues, which did not differ ( ≥ 0.63). Low-stem residue also had the greatest NDF digestibility (NDFD; < 0.01), whereas high-stem residue had greater NDFD than conventional residue ( < 0.01). Digestible energy was greatest for low-stem residue ( < 0.05) and did not differ between high-stem and conventional residues ( = 0.50). Reducing the proportion of stem in the bale through changes in the harvest method increased the nutritive quality of corn residue.

Multiparous, lactating, crossbred (Simmental × Angus) beef cows with spring-born calves at side (n = 16 per year; 4 per pasture) were used each of 3 yr to evaluate supplementing modified distillers grains plus solubles mixed with low-quality forage on cow and calf performance while grazing. Cow-calf pairs were assigned randomly to treatment with 2 replications (pasture) per year for 3 yr. Treatments were (1) recommended stocking rate of 9.46 animal-unit month/ha with no supplementation (CON) or (2) double the recommended stocking rate (18.9 animal-unit month/ha) and supplemented with a 30:70 modified distillers grains plus solubles:cornstalks (DM) mixture (SUPP). To replace 50% of grazed forage DMI, SUPP pairs were fed an average of 1.13% of BW (DM) over the grazing season. Pairs grazed adjacent smooth bromegrass pastures for 130 d during the summer. Gain was not different ( P = 0.19) between SUPP and CON cows (0.28 vs. 0.19 kg/d, respectively). Ending cow BW was not affected ( P = 0.46) by treatment. Similarly, calf gain was not affected ( P = 0.31) by supplementation. In studies where confined cow-calf pairs were fed average-quality (IVDMD = 52.9%) forage, DMI was 2.58% of pair BW. Based on these data, CON and SUPP pairs consumed 18.6 and 19.1 kg of DM, respectively, of total feed per pair daily. The SUPP pairs consumed 7.1 kg of DM/pair daily of the supplement, replacing approximately 35% of grazed forage intake. These data suggest mixtures of ethanol co-products and low-quality forages can be supplemented to replace grazed forage intake of cattle, allowing for increased stocking rate without affecting animal performance., (© 2017 American Registry of Professional Animal Scientists.)

Two finishing and 1 digestibility experiment evaluated the partial substitution of corn with corn silage and corn modified distillers grains with solubles (MDGS). Steers were used in Exp. 1 (n = 295; 467 ± 52 kg) and Exp. 2 (n = 225; BW = 348 ± 27 kg) in a 2 × 2 + 1 factorial arrangement of treatments with factors including corn silage (15 or 45%) and MDGS (20 or 40%) plus a control diet consisting of 5% cornstalks and 40% MDGS. In Exp. 1, there were tendencies for a corn silage × MDGS interaction for ADG, final BW, and G:F ( P ≤ 0.08). In the overall F-test for G:F, there were no differences between the control treatment and 15:20, 15:40, or 45:40 ( P ≥ 0.15), however, steers fed the control treatment had increased G:F compared to steers fed 45:20 treatment diets ( P = 0.03). In Exp. 2, there were no corn silage × MDGS interactions ( P ≥ 0.12). As corn silage increased in the diet, ADG, final BW, and G:F decreased ( P ≤ 0.01). As MDGS increased from 20 to 40%, ADG and G:F tended to improve ( P ≤ 0.07). In the overall F-test, the control was not different for G:F from 15:20, 45:20, or 45:40 ( P ≥ 0.15), but had a 4.8% poorer G:F compared to 15:40 ( P < 0.01). In Exp. 3, ruminally fistulated steers (n = 6) were used in a 5 × 6 Latin rectangle design and fed 15 or 45% corn silage with 20 or 40% MDGS as a 2 × 2 factorial. An additional diet consisting of 95% corn silage and 5% supplement was fed. There were no corn silage × MDGS interactions for nutrient intake, total tract digestibility, ruminal pH measurements, acetate: propionate ratio (A:P), or in-situ disappearance data ( P ≥ 0.31) for the 2 × 2 factorial. As corn silage increased in the diet, DMI, NDF intake, ruminal pH, A:P, in-situ NDF disappearance of corn bran, and DM disappearance of corn increased ( P ≤ 0.09) with decreases in DM and OM digestibility ( P ≤ 0.03). As MDGS increased in the diet, there was an increase in NDF intake, total volatile fatty acid concentration, and NDF disappearance of corn bran ( P ≤ 0.03) with no differences for any other tested variables ( P ≥ 0.13). In general, increasing corn silage in place of corn in finishing diets containing MDGS results in a modest reduction in ADG and G:F with increases in ruminal pH.

Corn plants were sampled over 2 consecutive years to assess the effects of corn hybrid maturity class, plant population, and harvest time on whole corn plant quality and yield in Nebraska. A finishing experiment evaluated the substitution of corn with corn silage in diets with corn modified distillers grains with solubles (MDGS). The first 2 harvest dates were at the mid- and late-silage harvest times whereas the final harvest was at the grain harvest stage of plant maturity. Whole plant yields increased as harvest time progressed (yr 1 quadratic P < 0.01; yr 2 linear P < 0.01). However, differences in TDN concentration in both years were quite minimal across harvest time, because grain percentage increased but residue NDF in-situ disappearance decreased as harvest time was delayed. In the finishing experiment, as corn silage inclusion increased from 15 to 55% (DM basis) by replacing dry rolled and high moisture corn grain with corn silage in diets containing 40% MDGS, DMI, ADG, and G:F linearly decreased ( P ≤ 0.01), with the steers on the 15% corn silage treatment being 1.5%, 5.0%, and 7.7% more efficient than steers on treatments containing 30, 45, and 55% corn silage, respectively. Calculated dietary NEm and NEg decreased linearly as corn silage inclusion increased indicating that net energy values were greater for corn grain than for corn silage. In addition, dressing percentage decreased linearly ( P < 0.01) as silage inclusion increased suggesting more fill as silage inclusion increases in diets. Cattle fed greater than 15% corn silage in finishing diets based on corn grain will gain slower and be slightly less efficient and likely require increased days to market at similar carcass fatness and size. When 30% silage was fed with 65% MDGS, DMI, and ADG were decreased ( P < 0.01) compared to feeding 30% silage with 40% MDGS suggesting some benefit to including a proportion of corn in the diet. Conversely, when 45% silage was fed with 40% MDGS, ADG, and G:F were greater ( P < 0.04) than when 45% silage was fed with just grain implying a greater energy value for MDGS than for corn grain. Substituting corn silage for corn grain in finishing diets decreased ADG and G:F which would increase days to finish to an equal carcass weight; however, in this experiment, increasing corn silage levels with MDGS present reduced carcass fat thickness without significantly decreasing marbling score.

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.

A data set of individual observations was compiled from digestibility trials to examine the relationship between the duodenal purine bases (PB) flow and urinary purine derivatives (PD) excretion and the validity of different equations for estimating rumen microbial N (Nm) supply based on urinary PD in comparison with estimates based on duodenal PB. Trials (8 trials, = 185) were conducted with male sheep fitted with a duodenal T-type cannula, housed in metabolic cages, and fed forage alone or with supplements. The amount of PD excreted in urine was linearly related to the amount of PB flowing to the duodenum ( < 0.05). The intercept of the linear regression was 0.180 mmol/(d·kg), representing the endogenous excretion of PD, and the slope was lower than 1 ( < 0.05), indicating that only 0.43% of the PB in the duodenum was excreted as PD in urine. The Nm supply estimated by either approach was linearly related ( < 0.05) to the digestible OM intake. However, the Nm supply estimated through either of 3 published PD-based equations probably underestimated the Nm supply in sheep.

Two experiments were conducted to evaluate the effects of ractopamine hydrochloride (RAC) dose and duration on growth performance and carcass characteristics of finishing steers. In Exp. 1, 336 crossbred steers (initial BW of RAC feeding = 539 kg [SD 22]) were used in a 2 × 2 factorial arrangement of treatments with one factor being RAC dose (0 or 200 mg/steer daily) and the other factor being RAC duration (28 or 42 d prior to harvest). There were no RAC dose × duration interactions ( ≥ 0.08) for growth performance or carcass characteristics. Feeding 200 mg RAC/steer daily increased ( < 0.01) live final BW by 9.0 kg compared with steers not fed RAC. Carcass-adjusted final BW, ADG, and G:F were greater ( < 0.01) for steers fed 200 mg RAC/d compared with steers not fed RAC. Hot carcass weight was 4.7 kg heavier ( < 0.01) for steers fed 200 mg RAC/d compared with steers not fed RAC. In Exp. 2, crossbred steers ( = 576; experiment initial BW = 408 kg [SD 29]) were used in a randomized block design with a 3 × 3 factorial arrangement of treatments. Factors included RAC dose (0, 300, and 400 mg/steer daily) and RAC duration (14, 28, or 42 d prior to harvest). There was a tendency ( ≤ 0.08) for an interaction of RAC dose × duration for final live BW, DMI, and live G:F; therefore, simple effects are presented. At 28 d, live final BW for steers fed 400 mg RAC/d were heavier ( < 0.01) than for steers fed 0 mg RAC/d. There was a tendency at 28 d for increased live final BW for steers fed RAC at 300 mg/d ( = 0.08) compared with steers fed RAC at 0 mg and for steers fed 400 mg RAC/d compared with steers fed 300 mg RAC/d ( = 0.06). Live final BW was greater ( < 0.01) for steers fed RAC for 42 d at 300 and 400 mg/d compared with steers fed 0 mg; however, live final BW was similar ( = 0.48) between steers fed 300 and 400 mg RAC/d. Despite no RAC dose × duration interaction ( = 0.30) for HCW, simple effects will be presented for consistency. Hot carcass weight was greater for steers fed 300 and 400 mg RAC/d for 28 and 42 d compared with steers fed 0 mg at 28 ( ≤ 0.02) and 42 d ( < 0.01). Feeding 300 mg RAC/d for 28 or 42 d increased HCW by 5.1 and 7.6 kg, respectively, compared with steers fed 0 mg RAC. Additionally, feeding 400 mg RAC/d for 28 or 42 d resulted in increases of 8.9 and 9.4 kg, respectively, in HCW compared with steers fed 0 mg RAC. In conclusion, our results confirm that feeding RAC improves growth performance and carcass weight, with an optimal duration of feeding RAC being 28 d.

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 determined effects of collection and preparation techniques on nutrient composition of masticate samples from esophageally fistulated cattle. In Exp. 1, 12 esophageally fistulated cattle were maintained on 2 precollection diets, high CP (24% CP; = 6) or low CP (7.7% CP; = 6), for 8 d. On d 9, the esophageal plug was removed, screen bottom bags were attached, and each cow was offered fresh grass. Immediately after fresh grass sample collection was complete, dry grass (hay) was offered and a sample was collected. Blood samples were collected and analyzed for serum urea nitrogen concentration. Masticate samples of both fresh and dry grass were divided and each was either squeezed by hand until no more saliva could be removed or remained unsqueezed. In Exp. 2, 10 esophageally fistulated cattle were fitted with either screen ( = 5) or solid ( = 5) bottom collection bags after removal of the esophageal plug and presented grass hay, fresh grass, alfalfa hay, or fresh alfalfa. In Exp. 1, the precollection diet did not affect ( = 0.49) CP content of masticate even though serum urea nitrogen tended to be greater ( = 0.08) for high- vs. low-CP precollection diets. Forage harvest type offered (fresh vs. hay) interacted ( = 0.01) with preparation technique (squeezed vs. unsqueezed) for CP, where CP decreased in squeezed fresh samples ( < 0.001) but not in squeezed grass hay samples ( = 0.98). In Exp. 2, ingestion greatly increased levels of ash ( < 0.001). Crude protein was greater ( < 0.004) before ingestion for all samples except grass hay ( = 0.43). Levels of NDF were similar before and after ingestion ( > 0.15) for all samples except fresh alfalfa, which was greater after ingestion ( = 0.002). Ingestion status did not affect in vitro OM disappearance (IVOMD; > 0.34) except for grass hay, which was greater after ingestion ( < 0.001). Bag type (screen vs. solid) did not affect ash and NDF ( > 0.31), except for fresh alfalfa, which were greater ( < 0.03) for solid bottom bags. Bag type did not affect alfalfa CP ( = 0.71) but did affect grass CP, which was lower ( = 0.02) for solid bottom bags. Bag type did not affect IVOMD ( > 0.33). More ( = 0.01) fresh forage than hay was recovered through the esophageal opening. Previous diet did not impact masticate samples but squeezing impacted CP levels of high-quality forage and therefore should not be performed. Nutrient values should be reported on an OM basis.

Twelve 2-ha, Nebraska Sandhills upland range paddocks were used in a 2-yr study to determine effects of stocking rate on grazed forage nutrient value in early summer. Paddocks contain a mixture of native cool- and warm-season grasses with forbs as a minor component. Stocking rates were 0 (control), 0.57 (light), and 0.85 (heavy) animal unit months per ha, respectively. Three esophageally fistulated cows collected diet samples on May 14 (d 0), May 21 (d 7), May 28 (d 14), and June 4 (d 21) in 2013 and 2014. Ten quadrats per paddock were clipped and separated into current or previous year growth on each diet sampling date. All samples were analyzed for CP, NDF, and in vitro OM disappearance, which was adjusted to an in vivo OM basis (). For diet samples, treatment interacted ( < 0.001) with sampling date for CP, NDF, and IVOMD. However, treatment and date did not interact ( ≥ 0.32) for clipped samples. Diets collected in control paddocks had greater ( < 0.05) IVOMD and CP and lower NDF compared with light and heavy stocking rate paddocks on d 7, 14, and 21 but light stocking rate paddocks did not differ ( ≥ 0.26) from heavy stocking rate paddocks on any sampling day except d 21 NDF ( = 0.03). In general, previous year growth IVOMD, CP, and NDF were not affected ( ≥ 0.11) by treatment. Generally, current year growth IVOMD and CP were not affected ( ≥ 0.22) by treatment. Current year growth NDF did not differ ( = 0.23) among stocking rates on d 0, but control paddock had lower ( = 0.02) NDF than light and heavy on d 7, 14, and 21. In stocked paddocks, diet samples had greater ( < 0.01) IVOMD and CP and lower NDF than current and previous year growth except IVOMD on d 0 where diet and current year growth did not differ ( = 0.34). Generally, in control paddocks, current year growth and diet samples had greater ( < 0.01) IVOMD and CP than previous year growth. Control paddocks had greater ( < 0.01) forage accumulation than stocked paddocks on d 7, 14, and 21; however, light and heavy stocked paddocks did not differ ( ≥ 0.29). On d 0 it was estimated that 96% of the diet was current year growth and only 4% previous year growth, whereas on d 21, 70% of the diet was current year growth vs. 30% previous year growth. Stocking pastures decrease current year growth forage mass and therefore diet nutritive value by forcing cattle to consume diets containing previous year growth in early summer.

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.

Two experiments were conducted with 192 steers each (during the winter [November to May] or summer [June to October]) to evaluate 3 diets with or without Yucca schidigera extract in a 3 × 2 factorial on steer growth performance and N mass balance. One factor was diet (DM basis): 1) 5% untreated corn stover, 51% corn, and 40% modified distillers grains plus solubles (MDGS; CON); 2) 20% calcium oxide-treated corn stover (CaO added at 5% of stover DM), 40% MDGS, and 36% corn (TRT); or 3) 20% untreated corn stover, 40% MDGS, and 36% corn (NONTRT). The other factor was dietary extract at 0 (NOYE) or 1.0 g/d per steer (YE). No interaction between diet and YE was detected (P > 0.51) for growth performance and carcass traits in winter and only for DMI in summer. Final BW, ADG, DMI, or G:F were not different (P ≥ 0.28) between cattle fed CON and TRT, whereas cattle fed NONTRT had lesser ADG, HCW, and G:F compared to CON and TRT in the winter experiment. During the summer, final BW and ADG tended to be greater (P ≥ 0.07) for CON compared to TRT. Cattle fed TRT had reduced (P < 0.01) G:F compared to CON. No difference was observed (P ≥ 0.36) between YE and NOYE in the winter experiment for performance or carcass traits. In the summer, cattle fed YE had greater (P < 0.02) HCW, ADG, and DMI compared to NOYE. In the summer experiment, cattle fed YE had greater (P < 0.01) N intake, N excretion, and amount of N lost (kg/steer) compared to NOYE, but no difference (P = 0.33) was observed for percentage of N volatilized (% of excretion). Diet had no effect (P > 0.18) on amount (kg/steer) or percentage of N volatized in the winter or summer. All diets had similar amounts (P > 0.13) of DM and OM removed from the pen surface in both summer and winter. Feeding CaO-treated corn stover as a partial grain replacement had no impact on performance in winter but decreased G:F in summer. Although high-fiber diets increased the amount of OM on pen surfaces, they did not impact N volatilized. Feeding a Y. schidigera extract did not affect N balance or manure characteristics.

Two studies were conducted to identify methods for treating crop residues to improve digestibility and value in finishing diets based on corn grain and corn wet distillers grain with solubles (WDGS). In Exp. 1, 336 yearling steers (initial BW 356 ± 11.5 kg) were used in a 2 × 3 + 1 factorial arrangement of treatments with 6 pens per treatment. Factors were 3 crop residues (corn cobs, wheat straw, and corn stover) and 2 treatments where crop residues were either fed (20% diet DM) in their native form (NT) or alkaline treated with 5% CaO (DM basis) and hydrated to 50% DM before anaerobic storage (AT). Intakes were not affected by diet (F test; P = 0.30). An interaction between chemical treatment and residue (P < 0.01) was noted for final BW, ADG, G:F, and HCW. Greater final BW was observed for treated stover (4.6%) and straw (5.6%) compared with NT residues; however, AT and NT cobs were similar. Treated straw (9.7%) and stover (12.5%) resulted in greater ADG (P < 0.01) and improved G:F (10.7% and 5.0%, respectively; P < 0.01) compared with NT forms. In Exp. 2, ruminally fistulated steers (n = 5) were used in an unbalanced 5 × 7 incomplete Latin square design with a 2 × 3 + 1 factorial arrangement of treatments. Factors were crop residue (corn cobs, wheat straw, and corn stover) and chemical treatment (NT or AT) fed at 25% of diet DM. Greater DM (73.7% vs. 66.1%; P < 0.01), OM (77.0% vs. 68.5%; P < 0.01), fat (89.2 vs. 85.2; P = 0.02), and NDF (66.8% vs. 51.5%; P < 0.01) digestibilities were noted for AT than for NT. However, no difference (P > 0.10) was observed between control (46% corn; DM basis) and AT (31% corn; DM basis) for DM digestibility (70.7% vs. 73.7%) or OM digestibility (72.1% vs. 77.0%). Dry matter intakes were not different between treated and untreated diets (P = 0.38), but lower (P < 0.01) NDF intake was observed for treated diets (3.1 vs. 3.5 kg/d), suggesting that CaO treatment was effective in solubilizing some carbohydrate. These data suggest that 15% replacement of corn and 10% untreated residue with treated forage result in a nutrient supply of OM similar to that of the control. The improvements in total tract fiber digestibility that occurred when treated forages were fed may have been related to increased digestibility of recoverable NDF and not to increased ruminal pH. Feeding chemically treated crop residues and WDGS is an effective strategy for replacing a portion of corn grain and roughage in feedlot diets.

A study was conducted to determine the rumen degradation and intestinal digestibility of crude protein (CP) and AA, and AA composition of the rumen-undegradable protein (RUP) from 3 sources of blood meal (BM1, BM2, and BM3), canola meal (CM), low-fat distillers dried grains with solubles (LFDG), soybean meal (SBM), and expeller soybean meal (ESBM). Two Holstein cows fitted with ruminal and proximal duodenal cannulas were used for in situ incubation of 16h and for the mobile bag technique. To correct for bacterial contamination of the RUP, 2 methods were used: purines and DNA as bacterial markers. Ruminal degradations of CP were 85.3, 29.8, 40.7, 75.7, 76.9, 68.8, and 37.0 ± 3.93% for BM1, BM2, BM3, CM, LFDG, SBM, and ESBM, respectively. Ruminal degradation of both total essential AA and nonessential AA followed a similar pattern to that of CP across feedstuffs. Based on the ratio of AA concentration in the RUP to AA concentration in the original feedstuff, ruminal incubation decreased (ratio <1) the concentrations of His, Lys, and Trp, and increased (ratio >1) the concentrations of Ile and Met across feedstuffs. Compared with purines, the use of DNA as bacterial marker resulted in a higher estimate of bacterial CP contamination for CM and lower estimates for LFDG and ESBM. Intestinal digestibility of RUP could not be estimated for BM1, BM3, and SBM due to insufficient recovery of residue. For the remaining feedstuffs, intestinal digestibility of RUP was highest for ESBM, followed by BM2 and LFDG, and lowest for CM: 98.8, 87.9, 89.7, and 72.4 ± 1.40%, respectively. Intestinal absorbable dietary protein was higher for BM2 compared with CM and LFDG, at 61.7, 17.9, and 20.7 ± 2.73% CP, respectively. As prices fluctuate, intestinal absorbable protein or AA may be used as a tool to aid in the selection among feedstuffs with different protein quality., (Copyright © 2014 American Dairy Science Association. Published by Elsevier Inc. All rights reserved.)

Pens of cattle with high Escherichia coli O157:H7 (STEC O157) prevalence at harvest may present a greater risk to food safety than pens of lower prevalence. Vaccination of live cattle against STEC O157 has been proposed as an approach to reduce STEC O157 prevalence in live cattle. Our objective was to create a stochastic simulation model to evaluate the effectiveness of pre-harvest interventions. We used the model to compare STEC O157 prevalence distributions for summer- and winter-fed cattle to summer-fed cattle immunized with a type III secreted protein (TTSP) vaccine. Model inputs were an estimate of vaccine efficacy, observed frequency distributions for number of animals within a pen, and pen-level faecal shedding prevalence for summer and winter. Uncertainty about vaccine efficacy was simulated using a log-normal distribution (mean = 58%, SE = 0.14). Model outputs were distributions of STEC O157 faecal pen prevalence of summer-fed cattle unvaccinated and vaccinated, and winter-fed cattle unvaccinated. The simulation was performed 5000 times. Summer faecal prevalence ranged from 0% to 80% (average = 30%). Thirty-six per cent of summer-fed pens had STEC O157 prevalence >40%. Winter faecal prevalence ranged from 0% to 60% (average = 10%). Seven per cent of winter-fed pens had STEC O157 prevalence >40%. Faecal prevalence for summer-fed pens vaccinated with a 58% efficacious vaccine product ranged from 0% to 52% (average = 13%). Less than one per cent of vaccinated pens had STEC O157 prevalence >40%. In this simulation, vaccination mitigated the risk of STEC O157 faecal shedding to levels comparable to winter, with the major effects being reduced average shedding prevalence, reduced variability in prevalence distribution, and a reduction in the occurrence of the highest prevalence pens. Food safety decision-makers may find this modelling approach useful for evaluating the value of pre-harvest interventions., (© 2013 Blackwell Verlag GmbH.)

Sixteen multiparous lactating Holstein cows were used in 2 experiments to evaluate the effects of reduced-fat dried distillers grains with solubles (RFDG) on milk production, rumen fermentation, intestinal microbial N flow, and total-tract nutrient digestibility. In experiment 1, RFDG was fed at 0, 10, 20, or 30% of diet dry matter (DM) to 12 noncannulated Holstein cows (mean ± standard deviation: 89 ± 11 d in milk and 674 ± 68.2 kg of body weight) to determine effects on milk production. In experiment 2, the same diets were fed to 4 ruminally and duodenally cannulated Holstein cows (mean ± standard deviation: 112 ± 41 d in milk; 590 ± 61.14 kg of body weight) to evaluate the effects on rumen fermentation, intestinal flow of microbial N, and total-tract nutrient digestibility. In both experiments, cows were randomly assigned to 4 × 4 Latin squares over 21-d periods. Treatments (DM basis) were (1) control (0% RFDG), (2) 10% RFDG, (3) 20% RFDG, and (4) 30% RFDG. Feed intake and milk yield were recorded daily. In both experiments, milk samples were collected on d 19 to 21 of each period for analysis of milk components. In experiment 2, ruminal pH was measured; samples of rumen fluid, duodenal digesta, and feces were collected on d 18 to 21. Microbial N was estimated by using purines and DNA as microbial markers. Milk yield was not affected by treatment and averaged 34.0 ± 1.29 kg/d and 31.4 ± 2.81 kg/d in experiments 1 and 2, respectively. Percentage of milk protein tended to increase in experiment 1; estimates were 3.08, 3.18, 3.15, and 3.19 ± 0.06% when RFDG increased from 0 to 30% in the diets. However, milk protein concentration was not affected in experiment 2 and averaged 3.02 ± 0.07%. Percentage of milk fat was not affected and averaged 3.66 ± 0.05% and 3.25 ± 0.14% in experiments 1 and 2, respectively. Total ruminal volatile fatty acids and ammonia concentrations were not affected by treatment and averaged 135.18 ± 6.45 mM and 18.66 ± 2.32 mg/dL, respectively. Intestinal microbial N flow was not affected by treatment; however, purines yielded higher estimates of flow compared with DNA markers. When averaged across treatments, intestinal flow of microbial N was 303 and 218 ± 18 g of N/d, using purines and DNA as the markers. Dry matter, organic matter, neutral detergent fiber, and nonfiber carbohydrate digestibility tended to increase with increasing inclusion of RFDG. Results from these experiments indicate that dairy rations can be formulated to include up to 30% RFDG while maintaining lactation performance, volatile fatty acids concentration, and intestinal supply of microbial N., (Copyright © 2014 American Dairy Science Association. Published by Elsevier Inc. All rights reserved.)

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.

Cattle weights can be highly variable and are influenced by many factors, including time of weighing, ambient temperature, feed intake, and cattle handling. A protocol of limit feeding has been in use since the 1980s that was designed to reduce variation in gut fill due to differences in intakes. Cattle are penned and fed a 50% hay, 50% wet corn gluten feed or grain diet (DM basis) at an estimated 2% of BW for at least 5 d, after which weights are taken on 2 consecutive d and averaged for a limit-fed BW (LFW). For this analysis, full-fed weights (FFW) also were taken before the limit-feeding period while cattle had ad libitum intakes. Data from 18 experiments were used to analyze differences within 2-d LFW and between LFW and FFW. For 10 of the 18 experiments, FFW also were measured on 2 consecutive d. Cattle included in this summary were grazing cornstalks, smooth bromegrass pasture, Bermuda grass pasture, fescue pasture, native range, or in a dry lot on a 70% forage diet. The largest differences between FFW and LFW for individual cattle were -39 to +44 kg over all 18 experiments. Differences between 2 consecutive d of LFW were -23 to +24 kg for all 18 experiments. Differences between 2 d of FFW were -14 to +34 kg in the 10 experiments measuring FFW on 2 consecutive d. There was not a clear relationship between FFW and LFW; each weighing scenario had unique environmental conditions that led to different relationships. Differences in both beginning and ending BW were compounded when calculating ADG. Average daily gain was calculated for 15 of the experiments on the basis of either LFW or FFW. Differences between LFW and FFW ADG were -0.29 to +0.31 kg/d. The maximum ADG based on FFW was 1.62 kg/d. This large ADG, on a forage based diet, was likely due to changes in gut fill rather than tissue gain. These data suggest that handling cattle in a similar manner when weighing is more important than limiting intakes to decrease variance between weights. However, limiting intake before collection of beginning and ending BW better estimates empty body weight of cattle, allowing for a more accurate determination of actual body tissue weight gain. Measuring weights accurately becomes especially crucial when evaluating multiple components within a system (e.g., cornstalks to pasture to feedlot). Feeding a standard diet between these components of the system minimizes differences in gut fill due to treatment and allows for a more accurate determination of each component's contribution to the total system.

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.

Preharvest control of Escherichia coli O157:H7 (STEC O157) may prevent human illness by reducing the presence of STEC O157 throughout the beef production chain. Immunization of cattle with a type III secreted protein vaccine inhibits colonization of cattle with STEC O157 and reduces the probability of fecal shedding and hide contamination. Our objectives were to perform a meta-analysis to estimate efficacy of a three-dose regimen of TTSP vaccine at reducing the presence of STEC O157 in the feces of feedlot cattle and to test factors that might modify vaccine efficacy. Pen-level data (n=184 pens, 1462 cattle) from four randomized controlled vaccine trials conducted from 2002 to 2008 at the University of Nebraska-Lincoln were analyzed. Factors explaining a culture-positive fecal sample were tested in generalized estimating equations logistic regression and log-binomial models. An autoregressive correlation structure was defined to account for clustering of repeated test-periods within block. Clustering or potential confounding by study was accounted for by treating study as a fixed effect. STEC O157 was detected from 661 of 5451 postvaccination fecal samples. The probability to detect STEC O157 postvaccination was 8.4% and 15.8% in vaccinated and unvaccinated cattle, respectively. Interactions between vaccination and (1) study; (2) prevalence of control pens within each time-place cluster; and (3) days from vaccination were not significant or fit poorly with observed data. Adjusting for study, cattle in pens receiving three doses of vaccine were less likely to shed STEC O157 (odds ratio=0.46, p<0.0001). Model-adjusted vaccine efficacy was 48% (95% confidence interval: 0.37-0.57). We concluded that a three-dose regimen type III secreted protein vaccine was efficacious at reducing the probability of detecting STEC O157 in the feces of cattle and that vaccine efficacy was not modified by study or level of prevalence observed in control pens.

Effects of organic and inorganic sources of S on intake, intake pattern, ruminal pH, VFA profile, and ruminal H2S gas concentration ([H2S]) were evaluated, which lead to development of a procedure to measure ruminal S availability for reduction [ruminal available S (RAS)] as well as compare with an estimated number [adjusted ruminal protein S (ARPS)]. Ruminally cannulated crossbred beef steers (n = 5; BW = 548 ± 46 kg) were assigned to 1 of 5 diets in a 5×5 Latin square design and fed ad libitum in five 21-d periods. Steers were fed a dry-rolled corn diet (CON), inorganic S source (ammonium sulfate; INORG), organic S source (corn gluten meal) fed at 9.8 (ORG-L) or 23% of diet DM (ORG-H), or wet distillers grains with solubles (WDGS) fed at 50% of diet DM. For the laboratory procedure, individual ingredients were incubated with ruminal fluid from heifers fed 60% corn-based diets (n = 2) and McDougall's buffer. Bottles were cooled in ice, centrifuged, and decanted, and the precipitate was analyzed for S. Steers fed INORG tended (P = 0.12) to consume 12% less DM. Total S intake was greater (P < 0.01) for steers fed WDGS (60 g/d) followed by ORG-H, and the lowest S intake was observed for CON (22 g/d). Intakes of ARPS and RAS were greater (P < 0.01) for steers fed WDGS followed by INORG, ORG-H, ORG-L, and CON diets. Steers fed WDGS and INORG diets spent 13% more time eating (P < 0.01) compared with other treatments. There was an interaction (P = 0.05) between treatment and time for ruminal [H2S]. Similar [H2S] were observed for steers fed INORG and WDGS diets (P = 0.28), which were greater (P ≤ 0.05) than other treatments. Greater ruminal [H2S] at 8 h compared with 13 h postfeeding was observed for steers fed ORG-H, ORG-L, and CON diets (P ≤ 0.04). Nearly 65% of ruminal [H2S] variation was explained (linear; P < 0.01) by RAS intake, ARPS explained 58% (linear; P < 0.01), S intake explained 29% (quadratic; P < 0.01), average ruminal pH explained 12% (linear; P < 0.01), and area below ruminal pH 5.6 explained 16% (linear, P < 0.01) of the variation. A 6% decrease in acetate (P = 0.01), 20% increase in propionate molar proportions (P = 0.02), and a lower acetate:proprionate ratio (P = 0.02) were observed for steers fed INORG compared with CON diet. The RAS concept is important for predicting ruminal [H2S] rather than just total S in the diet. Coefficients of RAS for individual ingredients can be predicted using in vitro procedures. Ruminal [H2S] may also modulate intake pattern.

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.

A total of 3,632 crossbred steers were used in 3 separate randomized complete-block designed finishing experiments. Data from Exp. 1 were analyzed separately whereas data were combined for Exp. 2 and 3, based on corn processing method used [Exp.1 = equal combination of dry-rolled and high-moisture (DRC:HMC); Exp. 2 and 3 = steam-flaked (SFC)]. Steers were fed 1 of 5 treatments to evaluate the effects of monensin and tylosin in feedlot diets containing 25% corn wet distillers grains with solubles (WDGS; DM basis). Treatments included: 1) corn-based diet (no WDGS) with 360 mg/d monensin and 90 mg/d tylosin (CORN+MT), 2) 25% wet distillers grains with solubles (WDGS-CON), 3) 25% WDGS with 360 mg/d monensin (WDGS+M), 4) WDGS with monensin and tylosin at same levels as treatment 1, and 5) WDGS with 480 mg/d monensin and 90 mg/d tylosin (WDGS+HIMT). In Exp. 1, WDGS+MT increased (P < 0.01) ADG (6.5%), G:F (6.9%), and HCW (3.0%) compared with CORN+MT. Alternatively, in Exp. 2 and 3, WDGS+MT had no effect on ADG (P = 0.18), decreased (P < 0.01) G:F by 3.2%, and did not affect HCW (P = 0.57) compared with CORN+MT. In Exp. 1, addition of monensin to a WDGS diet increased G:F by 3.1% (P = 0.03) and tended to increase G:F in Exp. 2 and 3 (P = 0.09) compared with WDGS-CON. For all experiments, addition of monensin and tylosin in a diet containing WDGS increased G:F (P < 0.01) and reduced total and severe liver abscesses (P < 0.01) compared with WDGS-CON. Additionally, HCW was increased in Exp. 2 and 3 (P < 0.01) and tended to increase in Exp. 1 (P = 0.09) when monensin and tylosin were fed in a WDGS diet compared with WDGS-CON. Feeding WDGS+MT reduced total liver abscesses by 79.3% (Exp. 1) and 57.6% (Exp. 2 and 3) compared with WDGS-CON. Compared with WDGS+MT, minimal differences were observed when monensin was fed at 480 mg/steer daily with tylosin in diets containing WDGS. Inclusion of WDGS in finishing steer diets did not alter effectiveness of monensin with tylosin in improving G:F and reducing prevalence of liver abscesses, regardless of corn processing method. Corn processing method appears to be an important factor in performance response to WDGS with feeding value of WDGS, measured as an increase in feed efficiency, being greater in a DRC:HMC-based diet compared with a SFC-based diet.

The objectives of this trial were to determine the rumen undegradable protein (RUP) of dried distillers grains with solubles (DDGS), to compare the estimates of duodenal bacterial CP (BCP) flow using diaminopumelic acid (DAPA) or DNA as bacterial markers, and to estimate duodenal protozoal CP (PCP) and yeast CP (YCP) flow when DDGS are fed. Three crossbred steers fitted with ruminal and double L-shaped duodenal cannulae (average BW 780 ± 137 kg) were used in a 3 treatment, 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, which is 0% DDGS but with 19.5% corn bran, 20% sorghum silage, 60% brome hay, 0.5% trace minerals, and 0.25% urea, 2) LOW DDGS, which is inclusion of 9.75% DDGS replacing equal percentage of corn bran, and 3) HIGH DDGS, which is inclusion of 19.5% DDGS completely replacing corn bran. Duodenal BCP flow was estimated using DAPA and DNA as bacterial markers. In addition, duodenal PCP and YCP flow were estimated using DNA markers. The value of DDGS RUP as a percent of CP was determined to be 63.0 ± 0.64%. Estimates of duodenal BCP flow using DAPA were 473, 393, and 357 ± 78 g/d (P = 0.09) for CONTROL, LOW DDGS, and HIGH DDGS, respectively. Estimates of duodenal BCP flow using DNA were 479, 397, and 368 ± 74 g/d (P = 0.14), respectively. Average BCP flow across treatments was unaffected (P = 0.71) by marker type and were 404 and 417 ± 83 g/d for DAPA and DNA markers, respectively. Estimates of duodenal PCP flow were 82, 80, and 78 ± 12 g/d (P = 0.64) for CONTROL, LOW DDGS, and HIGH DDGS, respectively. Estimates of duodenal YCP flow were 0.15, 1.94, and 4.80 ± 0.66 g/d (P < 0.01) for CONTROL, LOW DDGS, and HIGH DDGS, respectively. Duodenal BCP flow tended to decrease with DDGS inclusion, but estimates were not affected by marker type. In addition, DDGS did not affect duodenal PCP supply and provided small amounts of duodenal YCP. Overall, the value of DDGS RUP determined in this study will contribute to a better understanding of the effect of this coproduct in ruminant nutrition.

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.

In a 3-yr study, 135 crossbred steers (330 ± 10 kg) were used in a randomized complete block design to evaluate corn dried distillers grains plus solubles (DDGS) fed to yearling steers as a substitute for forage and N fertilizer and its effect on N use efficiency in yearling steers grazing smooth bromegrass pastures. Steers were initially stocked at 6.8 animal unit months (AUM)/ha on nonfertilized smooth bromegrass pastures (CONT), at 9.9 AUM/ha on smooth bromegrass pastures fertilized with 90 kg of N/ha (FERT), or at 9.9 AUM/ha on nonfertilized smooth bromegrass pastures with 2.3 kg (DM) of DDGS supplemented daily per steer (SUPP). Paddock was the experimental unit, with 3 replications per treatment per year for 3 yr. Paddocks were strip-grazed, and put-and-take cattle were used to maintain similar grazing pressure among treatment paddocks during the 160-d grazing season. Steers consumed less forage (P < 0.01), but total N intake for SUPP was greater (P < 0.01) per steer and per hectare than for FERT, and both were greater (P < 0.01) than for CONT. Nitrogen retention for steers in the SUPP treatment was increased (P < 0.01) by 31% compared with N retention in the CONT and FERT treatments. Nitrogen retention per hectare for SUPP was 30 and 98% greater (P < 0.01) than N retention per hectare for FERT and CONT, respectively. Nitrogen excretion per steer and per hectare were also greater (P < 0.01) for SUPP than FERT, and both were increased (P < 0.01) compared with CONT. Animal N use efficiency was similar (P = 0.29) for steers in the CONT, FERT, and SUPP treatments. However, system-based N use improved (P < 0.01) by 144% for SUPP compared with FERT. The DDGS increased N intake and N excretion in yearling steers. However, because of improvements in BW gain and increases in stocking rate of pastures, DDGS can be a useful tool to increase the efficiency of N use in smooth bromegrass grazing systems.

Six experiments were conducted to evaluate dietary cation-anion difference (DCAD) in concentrate diets on urinary pH, feedlot performance, and N mass balance. In Exp. 1, 15 wether lambs (33.5 ± 3.0 kg) in five 3 × 3 Latin squares were fed a basal diet of 82.5% dry-rolled corn (DRC), 7.5% alfalfa hay, 5% molasses, and 5% supplement with different proportions of anionic and cationic salts. The DCAD was -45, -24, -16, -8, 0, +8, +16, +24, +32, and +40 mEq per 100 g of DM with the control basal diet (DCAD = +8) included in each square. Urinary pH increased (cubic, P < 0.01) as DCAD increased and DMI increased linearly (P < 0.01) with increasing DCAD. In Exp. 2 and 3, 8 Holstein steers (312 ± 24 kg) were used in 2 consecutive 4 × 4 Latin squares. Steers were fed either the same basal diet as Exp. 1 or a basal diet with 20% wet distillers grains (WDGS) replacing DRC. In Exp. 2, DCAD was adjusted to -2, -12, and -22 mEq per 100 g of DM from the basal diet (DCAD = +8) and DCAD was adjusted in Exp. 3 to -12, -22, and -32 mEq per 100 g of DM from the basal WDGS diet (DCAD = -2). Urinary pH decreased linearly as DCAD decreased (P < 0.01) in both experiments, whereas DMI decreased linearly in Exp. 2 (P = 0.02) but not Exp. 3 (P = 0.96). In Exp. 4, 6 crossbred steers (373 ± 37 kg) were used in a 2-period crossover design. Steers were fed the same basal diet as Exp. 3 with DCAD of -16 (NEG) and +20 (POS) mEq per 100 g of DM. Urinary pH and DMI (P < 0.05) were less for cattle fed the NEG diet compared with POS. In 2 experiments, steers (n = 96 each) were fed NEG or POS as calves (260 ± 22 kg of BW) for 196 d from November to May (Exp. 5) or as yearlings (339 ± 32 kg of BW) for 145 d from June to October (Exp. 6). Final BW, DMI, ADG, and HCW were not different (P > 0.11) among treatments in either experiment. Efficiency of BW gain was increased (P = 0.05) for steers fed NEG compared with POS in Exp. 5 but was not different (P = 0.11) in Exp. 6. Amount of N intake, retention, excretion, and manure N (kg/steer) were not different (P > 0.11) among treatments in either experiment. Manure pH (soil, feces, and urine) was decreased (P < 0.01) in pens fed NEG compared with POS in both experiments. Amount of N lost (kg/steer) was not different (P = 0.44) in Exp. 5, but tended (P = 0.09) to be 10.6% greater for POS compared with NEG in Exp. 6. Urinary pH was decreased by reducing DCAD, but this had minimal effect on N losses in open feedlot pens in these experiments.

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.

Environmental regulations on greenhouse gas (GHG) emissions from corn (Zea mays L.)-ethanol production require accurate assessment methods to determine emissions savings from coproducts that are fed to livestock. We investigated current use of coproducts in livestock diets and estimated the magnitude and variability in the GHG emissions credit for coproducts in the corn-ethanol life cycle. The coproduct GHG emissions credit varied by more than twofold, from 11.5 to 28.3 g CO(2)e per MJ of ethanol produced, depending on the fraction of coproducts used without drying, the proportion of coproduct used to feed beef cattle (Bos taurus) vs. dairy or swine (Sus scrofa), and the location of corn production. Regional variability in the GHG intensity of crop production and future livestock feeding trends will determine the magnitude of the coproduct GHG offset against GHG emissions elsewhere in the corn-ethanol life cycle. Expansion of annual U.S. corn-ethanol production to 57 billion liters by 2015, as mandated in current federal law, will require feeding of coproduct at inclusion levels near the biological limit to the entire U.S. feedlot cattle, dairy, and swine herds. Under this future scenario, the coproduct GHG offset will decrease by 8% from current levels due to expanded use by dairy and swine, which are less efficient in use of coproduct than beef feedlot cattle. Because the coproduct GHG credit represents 19 to 38% of total life cycle GHG emissions, accurate estimation of the coproduct credit is important for determining the net impact of corn-ethanol production on atmospheric warming and whether corn-ethanol producers meet state- and national-level GHG emissions regulations.

Three experiments were conducted examining the effects of feeding different levels of dried distillers grains (DDG) and different proportions of condensed distillers solubles (CDS) added to DDG on performance and digestibility in forage-fed steers. In Exp. 1, a total of 120 individually fed crossbred steers (276 +/- 31 kg) were used in a randomized complete block design with a 4 x 5 factorial arrangement of treatments. Factors included DDG supplementation level (0.25, 0.50, 0.75, or 1.0% of BW daily) and proportion of CDS in DDG (0.0, 5.4, 14.5, 19.1, and 22.1% of DDG DM). A basal diet of 58.8% alfalfa hay, 39.2% sorghum silage, and 2% vitamin and mineral supplement (DM basis) was fed for ad libitum intake. As the level of DDG increased, intake of forage decreased linearly (P < 0.01), intake of DDG increased linearly (P < 0.01), and total DMI increased quadratically (P = 0.06). A DDG level x CDS level interaction (P < 0.01) was observed for ADG and G:F. The 0.0, 5.4, 14.5, 19.1, and 22.1% CDS treatments had the greatest ADG when DDG was supplemented at 0.75, 1.0, 1.0, 0.75, and 0.50% of BW daily, respectively. In Exp. 2, four crossbred steers (295 +/- 19 kg) were used in a 3-period switchback design. A basal diet of 58.8% alfalfa hay, 39.2% brome hay, and 2% vitamin and mineral supplement (DM basis) was fed at 95% of ad libitum intake. Treatments were DDG containing 0.0 or 22.1% CDS supplemented at 1.0% of BW daily. Apparent total tract digestibility was measured by total fecal collection. No differences between treatments were observed for digestibility of DM, OM, or NDF (P >/= 0.14). Digestibility of ether extract was greater (P = 0.02) in steers supplemented with DDG containing 22.1% CDS. In Exp. 3, two ruminally and duodenally cannulated Holstein steers (663 +/- 24 kg) were used to estimate DM and CP digestion of the DDG fed in Exp. 1 using the mobile bag technique. Basal diets were the same as fed in Exp. 1 and steers were supplemented with DDG at 0.5% of BW daily. Ruminal DM digestibility increased linearly (P < 0.01), and postruminal and total tract DM digestibility increased quadratically (P = 0.02 and P = 0.03, respectively) as the level of CDS increased. Level of CDS may affect growing steer performance because depressions in ADG and G:F were observed as intake of ether extract increased. A clear explanation for the interaction between the DDG supplementation level and the CDS level on growing steer performance was not evident in the digestion experiments.

In a 3-yr study, corn dried distillers grains plus solubles (DDGS) were evaluated as a substitute for forage and N fertilizer in yearling steers grazing smooth bromegrass. A total of 135 steers (330 +/- 10 kg) were used in a randomized complete block design to measure the effects of DDGS supplementation and N fertilization on animal and pasture performance. Steers were initially stocked at 6.8 animal unit month (AUM)/ha on nonfertilized smooth bromegrass pastures (CONT), at 9.9 AUM/ha on smooth bromegrass pastures fertilized with 90 kg of N/ha (FERT), or at 9.9 AUM/ha on nonfertilized smooth bromegrass pastures with 2.3 kg of DDGS DM supplemented daily (SUPP). Paddock was the experimental unit, with 3 replications per year for 3 yr. Paddocks were strip-grazed and put-and-take cattle were used to maintain similar grazing pressure among treatment paddocks during the 160-d grazing season. In vitro DM disappearance declined quadratically (P < 0.01), whereas CP and standing crop showed cubic responses (P < 0.01) throughout the grazing season. Crude protein was greater (P < 0.05) for FERT compared with CONT and SUPP. Standing crop was 18% greater (P < 0.01) for FERT than CONT and was 10% greater (P < 0.01) than SUPP. Adjusted stocking rates (AUM/ha) were greater (P < 0.01) for FERT and SUPP compared with CONT. Final BW were greater (P < 0.01) for SUPP steers compared with CONT and FERT steers. Similar results were observed for ADG, with SUPP steers gaining more (P < 0.01) compared with CONT and FERT steers. Total BW gain per hectare was increased (P < 0.01) by 53% with FERT and by 105% with SUPP. Feedlot ADG was similar among treatments (P = 0.88), and SUPP steers maintained their BW advantage through the finishing phase. Dried distillers grains can be used to substitute effectively for N fertilizer by increasing the performance of yearling steers grazing smooth bromegrass and increasing stocking rates compared with nonfertilized pastures.

Two experiments were conducted to determine the effect of corn processing method and corn wet distillers grains plus solubles (WDGS) level on steer performance and metabolism. In Exp. 1, 480 crossbred steer calves (314 +/- 18 kg of BW) were used in a finishing experiment with a randomized complete block design and a 3 x 4 treatment structure. Diets were based on dry-rolled (DRC), high-moisture (HMC), or steam-flaked corn (SFC) with increasing levels of WDGS (0, 15, 27.5, or 40%; DM basis). A corn processing x WDGS level interaction (P < 0.01) was observed for ADG and G:F. Average daily gain and G:F increased linearly (P < 0.01) in steers fed DRC; ADG increased quadratically (P = 0.04) and G:F increased linearly (P = 0.02) in steers fed HMC; and ADG decreased quadratically (P = 0.02) with no change in G:F (P = 0.52) in steers fed SFC as WDGS increased. In Exp. 2, 7 ruminally fistulated steers (440 +/- 41 kg of BW) were used in a 6-period crossover design with 3 x 2 factorial treatment structure. Diets were the same as those fed in Exp. 1, except they contained only 2 levels of WDGS (0 or 40% of diet DM). Total tract starch digestibility was greater (P < 0.01) for steers fed SFC than for steers fed DRC or HMC. Minimum ruminal pH was less (P < 0.01) for steers fed SFC than for steers fed HMC or DRC. Variance of ruminal pH was different among all 3 processing methods with DRC < HMC < SFC (P < 0.10). In situ 22-h DM digestibility of DRC and HMC and starch digestibility of DRC were greater (P < 0.10) in steers fed DRC compared with steers fed HMC or SFC. Steers fed 0% WDGS had less (P < or = 0.02) intake of DM, OM, NDF, and ether extract compared with steers fed 40% WDGS. Total tract digestibility of DM and OM was greater (P < or = 0.08) and digestibility of ether extract tended (P = 0.11) to be less for steers fed 0% WDGS compared with steers fed 40% WDGS. Maximum ruminal pH and pH variance were greater (P < or = 0.08) in steers fed 0% WDGS. A corn processing x WDGS level interaction (P = 0.09) was observed for ruminal acetate to propionate ratio (A:P). Within diets containing 0% WDGS, A:P in steers fed SFC was less (P < or = 0.08). In diets containing 40% WDGS, A:P was similar between processing methods and not different from the SFC with 0% WDGS. The corn processing x WDGS level interaction observed in the finishing experiment may be due to the decreased ruminal A:P in DRC and HMC diets with 40% WDGS.