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The objective was to determine effects of old and new rubber matting in a slatted, indoor cattle feeding facility on cattle growth performance, locomotion, and carcass characteristics. In experiment 1, fall-born Angus × Simmental steers (N = 207; body weight = 222 ± 38 kg) were blocked by weight and assigned to 32 pens. Pens were randomly assigned to 1 of 4 treatments: no matting/concrete (CONC1), 12-yr-old Animat Pebble matting (OLD1), new Animat Maxgrip matting (MG), and new Animat Pebble matting (PEB1). Steers were fed a common diet for 209 d with a minimum stocking density of 3.40 m2 per animal. Final body weight (BW) and average daily gain (ADG) were affected (P = 0.02 and P < 0.01, respectively) by treatment with steers on PEB1 finishing heaviest with the greatest growth, MG and CONC1 intermediate, and OLD1 finishing at the lightest final BW with the least growth. Flooring treatment did not affect overall dry matter intake (DMI; P = 0.16) or gain to feed ratio (G:F; P = 0.94). Flooring treatment did not affect (P ≥ 0.19) any carcass traits. Locomotion scores (LS) were affected (P < 0.01) by flooring treatment with CONC1 having the worst mobility while OLD1, MG, and PEB1 were similar (P ≥ 0.24). Locomotion score had a day effect (P < 0.01) where cattle gait and mobility worsened as days on feed increased. In experiment 2, fall-born Angus × Simmental steers (N = 189; BW = 352 ± 43 kg) were blocked by weight and assigned to 21 pens. Pens were randomly assigned to 1 of 3 treatments: no matting/concrete (CONC2), 15-yr-old Animat Pebble matting (OLD2), and new Animat Pebble matting (PEB2). Steers were fed a common diet for 152 d with a stocking density of 2.65 m2 per steer. After 152 d on feed, flooring treatment did not affect (P ≥ 0.30) BW, ADG, or DMI nor did treatment affect (P ≥ 0.17) carcass traits. However, steers housed on OLD2 or PEB2 had improved locomotion scores (P = 0.02) compared with steers housed on CONC2. Locomotion score had a day effect (P < 0.01) as cattle gait and mobility worsened with greater number of days on feed, regardless of treatment. Overall, results suggest that new rubber matting increased ADG and HCW during a 209-d trial when cattle were stocked at 3.4 m2 in small pens and that rubber matting regardless of age improved cattle locomotion scores in slatted indoor feeding facilities., (© The Author(s) 2022. Published by Oxford University Press on behalf of the American Society of Animal Science. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.)

The objectives of this study were to compare ruminal total tract digestibility, bacterial communities, and eating and rumination activity between Holstein and Angus steers fed grain- or forage-based diets. Six Holstein steers (average body weight [BW] = 483 ± 23 kg) and six Angus steers (average BW = 507 ± 29 kg), previously fitted with rumen cannulae, were fed in a crossover design with a 2 × 2 factorial arrangement of four treatments: 1) Holsteins fed a grain-based diet, 2) Holsteins fed a forage-based diet, 3) Angus fed a grain-based diet, and 4) Angus fed a forage-based diet. Each period was 35 d with 26 d of diet adaptation and 9 d of sample collection. On days 1 and 2 of collection, feeding activity was recorded for 48 h. On day 3, rumen contents were sampled to measure ruminal pH at 0, 3, 6, 12, and 18 h after feeding. A portion of the strained ruminal fluid was subsampled at 0, 3, and 6 h for volatile fatty acids (VFA) analysis. Rumen contents were subsampled at 3 h for analysis of bacterial communities. From day 4 to 8, total fecal excretion, feed, and refusals samples were collected and analyzed for dry matter (DM), neutral detergent fiber (NDF), and starch. On days 8 and 9 (0 and 3 h post-feeding, respectively), total reticulorumen evacuation was conducted and contents were weighed. Data were analyzed using the MIXED procedures in SAS (v9.4 SAS Inst. Inc., Cary, NC). Repeated measures were used to analyze changes in ruminal pH and VFA over time. There were no interactions of diet × breed (P ≥ 0.07). While the main effects of diet were expected, unique to these data is the fact that bacterial diversity and richness were reduced (P < 0.01) in cattle fed grain-based diets. There was no main effect (P > 0.34) of breed on total tract DM, organic matter, and starch digestibility, but Angus cattle had greater (P = 0.01) NDF digestibility than Holsteins. The increased NDF digestibility may be associated with a numerical (P = 0.08) increased numbers of bacterial species in Angus steers compared with Holstein steers. Holstein steers also spent more time (P ≤ 0.05) ruminating than Angus steers. There was no effect (P > 0.80) of breed on reticulorumen content at feeding time; however, Holstein steers had greater (P = 0.04) reticulorumen content on a wet basis 3 h post-feeding. Although Holstein steers spent more time ruminating, Angus steers were better able to digest NDF when compared with Holsteins, regardless of basal diet, and this improvement may be related to changes in bacterial communities in the rumen or to rumination activity., (© The Author(s) 2020. Published by Oxford University Press on behalf of the American Society of Animal Science. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.)

The objectives of this research were to test interactions of supplement type, liquid versus dry, and forage type, hay versus corn stover, on digestibility and ruminal metabolism of beef cattle. Ruminally fistulated steers were fed in a replicated 4 × 4 Latin square with a 2 × 2 factorial arrangement of treatments: 1) hay with liquid supplement, 2) hay with dry supplement, 3) corn stover with liquid supplement, and 4) corn stover with dry supplement. The liquid supplement was molasses and glycerin based (23.3% CP and 1.63 Mcal/kg NEm) whereas the dry supplement was ground corn based (16.8% CP and 1.81 Mcal/kg NEm). Each period, steers were adapted to diets for 14 d and samples were collected for 8 d. In situ disappearance was determined by a 24-h incubation of Dacron bags, containing soybean hulls, in the rumen. There were no interactions ( ≥ 0.25) of supplement and forage type on DMI, apparent total tract digestibility, or ruminal pH. There was a tendency ( = 0.08) for a forage × supplement type interaction for in situ NDF disappearance (ISNDFD). There were no differences in ISNDFD in steers fed hay, but liquid supplement increased ISNDFD in steers fed corn stover. There were no main effects ( ≥ 0.12) of supplement type on DMI, apparent total tract or in situ digestibility, or ruminal pH. There was a supplement × hour interaction ( = 0.04) for acetate concentrations. Although no effect occurred at 0 h after feeding, at 3 and 6 h after feeding, acetate concentrations were reduced in steers fed liquid supplements when compared with those fed dry supplements. In addition, there was a supplement × hour ( = 0.02) interaction for butyrate concentrations, where at all time points, butyrate concentrations increased ( ≤ 0.01) in steers fed liquid supplements when compared with those fed dry supplements. Steers fed hay had increased DMI ( < 0.01) and apparent total tract NDF digestibility ( = 0.07) when compared with steers fed corn stover, regardless of supplement type. At 0, 1.5, and 18 h after feeding, ruminal pH was greater ( ≤ 0.01) in cattle consuming corn stover when compared with those fed hay, regardless of supplement type. However, steers fed hay had increased ( < 0.01) concentrations of acetate and total VFA compared with steers fed corn stover, regardless of supplement. Feeding liquid supplement increased ISNDFD when steers were fed corn stover; however, these changes were not associated with differences in total tract digestibility. Regardless of forage type fed, the liquid supplement increased ruminal butyrate concentrations.

Objectives of this experiment were to: 1) determine appropriate test length, timing, and repeatability of DMI, ADG, and efficiency over different biological time points; 2) determine the efficacy of using decoupled performance and intake data to generate accurate feed efficiency measures; and 3) determine the relationship between forage-and grain-feed efficiency measures. Over 2 yr, Charolais crossbred heifers ( = 308) and steers ( = 320) were fed for two 70 d periods and DMI, ADG, and 12th rib fat thickness were recorded. Steers were fed grain-based diets during the growing and finishing periods to determine the effects of test period and timing on DMI and feed efficiency. Heifers were fed forage during the growing period and grain during the finishing period to test the effect of diet type on measures of DMI and feed efficiency. For each 70 d test period, individual DMI was recorded using the GrowSafe (Airdrie, AB) system. Residual feed intake (RFI) was calculated for each test period. Total feeding period ADG (FP&#95;ADG) was calculated for steers by regressing all weights taken from feedlot arrival to final BW, which was calculated by dividing HCW by a standard dressing percentage (63%). Dry matter intake and RFI were correlated (r 0.56; < 0.01, and 0.63; < 0.01, respectively) for the growing and finishing periods of grain-fed steers. Average daily gain was not repeatable ( = 0.11; 0.06) across both test periods for steers. However, growing and finishing ADG were correlated ( = 0.58; < 0.01, and = 0.69; < 0.01, respectively) to FP&#95;ADG. To assess the potential of shortening the intake test, DMI was analyzed in 7 d increments for grain-fed steers during the growing and finishing periods. Regardless of test length, from 7 to 70 d, DMI was strongly correlated ( ≥ 0.87; < 0.01) to total DMI during the growing period. Heifer forage DMI was correlated ( = 0.58; < 0.01) to grain DMI; subsequently, forage and grain RFI were moderately correlated ( = 0.40; < 0.01). This study suggests that DMI is repeatable across varying stages of maturity in cattle, and accurate feed efficiency measures can be obtained in either the growing or finishing period. The relationship of forage and grain DMI and efficiency in heifers suggests that measures of DMI and feed efficiency in heifers are relevant, regardless of diet fed. Intake evaluation periods can be shortened with minimal effects on the accuracy of predicting individual animal DMI.

Objectives were to determine the interaction of prepartum supplement level and age at weaning on cow BW, BCS, milk production, reproduction, and calf performance up to weaning in a fall-calving system over 2 yr. Mature, multiparous, Angus × Simmental cows (yr 1: 326 cows, 9 pastures, BW = 632 ± 67 kg, and BCS = 5.7 ± 0.58; yr 2: 383 cows, 9 pastures, BW = 606 ± 70 kg, and BCS = 5.8 ± 0.74) were used in a split-plot design that included 3 supplement levels-no supplement (NS), low supplement (LS; 2.16 kg∙cow∙d), or high supplement (HS; 8.61 kg∙cow∙d)-and 2 ages at weaning-78 ± 11 d of age (early weaned; EW) or 186 ± 11 d of age (normal weaned; NW). Cows grazed endophyte-infected tall fescue/red clover pastures and were bunk fed supplement (70% dried distillers' grains with solubles and 30% soybean hulls) 103 ± 11 d prepartum to 2 ± 11 d postpartum. Cow BW was greater ( < 0.01) for cows fed HS at precalving (49 ± 11 d prepartum), postcalving (26 ± 11 d postpartum), and postbreeding (81 d after AI) compared with cows fed NS and LS. Prepartum supplementation did not affect ( ≥ 0.62) calf birth BW, percent of calves dead at birth, or percent of cows calving unassisted. Prepartum supplementation tended ( = 0.10) to improve AI conception. Early weaning increased ( ≤ 0.05) AI conception and postbreeding cow BW and BCS compared with cows with NW calves. Neither prepartum supplementation nor age at weaning affected ( ≥ 0.28) overall pregnancy rate. At time of early weaning, BW was increased ( = 0.05) for steers from cows fed LS compared with steers from cows fed NS. Steer BW at time of normal weaning and ADG between early and normal weaning was greater ( < 0.01) for EW steers compared with NW steers. A year × age at weaning interaction occurred ( < 0.01) for ultrasound marbling score at time of normal weaning. In yr 1, marbling was decreased ( = 0.04) for EW steers compared with NW steers; however, in yr 2, marbling was increased ( < 0.01) for EW steers compared with NW steers. In conclusion, there was no interaction between level of supplement during late gestation and age at weaning on cow BW, BCS, milk production, AI conception, and overall pregnancy rate in mature beef cows nor in their steer progeny's BW or ultrasound marbling. Both prepartum supplementation and early weaning improved cow BW, BCS, and reproduction. Minimal effects of dam prepartum supplement level on calf performance up to weaning were observed. Early weaning improved calf growth but had inconsistent effects on ultrasound marbling across years.

The objectives of this study were to determine the effect of fat concentration from corn distillers' solubles (CDS), fed during the growing phase, on DMI, gain, carcass traits, digestibility, ruminal metabolism, and methane emissions of steers. In Exp. 1, 40 steers (age = 136 ± 20 d; BW = 185 ± 11 kg) were randomly allotted to 1 of 5 dietary treatments: 1) a cosrn-based gro\wing diet (CNT), 2) 0% CDS, 3) 10% CDS, 4) 19% CDS, or 5) 27% CDS. Diets 2 through 5 included coproducts (corn gluten feed and soybean hulls) and were formulated to achieve fat concentrations of 3, 5, 7, and 9%, respectively. Diets were fed once daily for 106 d (growing phase). All steers were fed a corn-based diet from d 107 to 196. Contrasts were used to examine 1) the difference between CNT and 10% CDS and 2) linear and quadratic effects of CDS inclusion. During the growing phase, steers fed CNT had increased ( < 0.01) ADG and G:F compared with steers fed 10% CDS. Increasing CDS inclusion increased (linear, ≤ 0.02) ADG and G:F. Overall, steers fed CNT had increased ( < 0.01) ADG compared with steers fed 10% CDS, but increasing CDS inclusion had no effect ( = 0.19) on overall ADG. Overall DMI and G:F were not different ( ≥ 0.16) in any contrast. There was a trend (Linear; = 0.08) for ultrasound marbling at d 196 to increase as CDS inclusion increased; however, there were no effects ( ≥ 0.20) of treatment on carcass marbling or quality grade. In Exp. 2, 5 steers (BW = 335 ± 56 kg) were fed Exp. 1 diets for ad libitum intakes in a 5 × 5 Latin square design. Apparent DM digestibility increased (linear, = 0.02) with increasing dietary CDS inclusion. Steers fed CNT had greater ( = 0.01) DM digestibility than those fed 10% CDS. Fat digestibility increased (linear, < 0.01) in steers with increasing CDS, but NDF and ADF digestibility were not affected ( ≥ 0.17) by treatment. Similarly, ruminal pH and VFA concentrations were not affected ( ≥ 0.13). Also, there was no difference ( ≥ 0.37) in ruminal methane emissions (g/h). In conclusion, feeding corn during the growing phase increased overall ADG compared with 10% CDS coproduct-based diet but did not affect carcass traits or methane production. Increasing dietary fat inclusion from CDS in coproduct-based diets linearly increased DM and fat digestibility and predicted marbling scores via ultrasound but did not affect marbling at slaughter, NDF digestibility, propionate, or methane production.

Objectives were to evaluate the effects of replacing corn in feedlot finishing diets with processed corn stover (CS), processed by various combinations of chemical and physical methods, and modified wet distillers grain with solubles (MWDGS) on growth performance, carcass characteristics, digestibility, and ruminal metabolism of cattle. Corn stover was physically processed (ground or extruded) and chemically processed with alkaline agents (CaO and NaOH) to reduce the crystallinity of the lignocellulosic structure. In Exp. 1 steers ( = 18, initial BW = 385 ± 32 kg) and heifers ( = 41, initial BW = 381 ± 27 kg) were allotted to 1 of 5 dietary treatments: 1) 55% dry, cracked corn, 35% MWDGS, 5% vitamin-mineral supplement, and 5% untreated ground CS (), 2) CS treated with 5% CaO (DM basis) and stored in an Ag-Bag (BGCS), 3) CS treated with 5% CaO (DM basis) and extruded (5 EXCS), 4) CS treated with 4% CaO and 1% NaOH (DM basis) and extruded (4,1 EXCS), or 5) CS treated with 3% CaO and 2% NaOH (DM basis) and extruded (3,2 EXCS). Extruded CS was hydrated to 34% moisture, then an additional 16% water was added, as a solution carrying CaO or NaOH or both, via a calibrated pump during processing through a dual-shafted encased extruder (Readco Kurimoto Continuous Processor, York, PA) with the desired exiting temperature of 76.7°C ± 2.8°C. All treated CS diets contained 20% CS and 40% MWDGS (DM basis) to replace 20% corn when compared to CON. There were no effects ( ≥ 0.20) of dietary treatment on ADG, G:F, 12th-rib back fat, marbling score, LM area, or yield grade. However, cattle fed CON had increased ( = 0.02) DMI compared to cattle fed the treated CS diets. In Exp. 2, using the same diets as fed in Exp. 1, ruminally cannulated steers ( = 5; initial BW = 417 ± 21 kg) were fed for 90% of ad libitum intake in a 5 × 5 Latin square design. Apparent digestibility of NDF and ADF increased ( < 0.01) when cattle were fed treated CS diets compared with CON, regardless of the treatment applied. Ruminal pH was reduced ( = 0.02) in cattle fed BGCS from 0 to 6 h postfeeding compared with cattle fed all other diets. Cattle fed the treated CS diets had the greatest ( < 0.01) mean acetate concentrations, which increased ( = 0.01) total VFA concentrations. Replacing a portion of the corn with treated CS in feedlot diets containing MWDGS increased fiber digestibility without affecting feedlot cattle gain, efficiency, marbling score, or LM area.

The objectives of this study were to determine the effects of feeding dried corn distillers grains (DDGS) or modified wet corn distillers grains (MDGS) with or without CaO treatment to feedlot steers on 1) growth performance and carcass characteristics and 2) diet digestibility, pattern of intake, and meal distribution. In Exp. 1, steers (n = 139; average initial BW = 336 ± 75 kg) were used in a randomized complete block design. Treatments were arranged in a 2 × 2 factorial design, and pens were randomly allotted to 1 of the 4 dietary treatments (DM basis): 1) 50% DDGS untreated, 2) 48.8% DDGS treated with 1.2% CaO, 3) 50% MDGS untreated, or 4) 48.8% MDGS treated with 1.2% CaO. The remainder of the diet was corn husklage, dry rolled corn, and vitamin and mineral supplement. In Exp. 2, fistulated steers (n = 8; average initial BW = 540 ± 250 kg) were used in a replicated 4 × 4 Latin square design with the same dietary treatments as in Exp. 1. There was no interaction (P ≥ 0.14) between distillers grains plus solubles (DGS) and CaO inclusion for DMI, ADG, final BW, or USDA yield and quality grades. However, steers fed CaO-treated DGS had decreased (P < 0.01) DMI, regardless of DGS type. Because CaO treatment decreased DMI without affecting (P = 0.66) ADG, steers fed CaO-treated DGS had increased (P < 0.01) G:F compared to steers not fed CaO. The variation in DMI found in this experiment could be explained by differences in meal size and distribution. Steers fed CaO-treated DGS ate a similar (P = 0.36) number of meals but ate smaller (P < 0.01) meals. No effects (P ≥ 0.55) of CaO treatment or its interaction with DGS type were found for apparent total tract DM or NDF digestibility. However, steers fed MDGS had increased (P < 0.01) NDF digestibility compared to steers fed DDGS. In conclusion, CaO treatment of DGS improved feed efficiency when DGS-based diets were fed but did not improve digestibility.

Two experiments were conducted to determine the effect of increasing dietary CaO on ruminal fermentation, diet digestibility, performance, and carcass characteristics of feedlot steers fed 60% dried distillers grains with solubles ( DDGS: ). In Exp. 1, 120 steers were allotted by weight (355 ± 7.9 kg) to 1 of 4 treatments containing 60% DDGS, 20% corn silage, 13.5 to 14.4% ground corn, 4% supplement, and 0 to 2.5% limestone on DM basis to determine the effects of CaO on performance and carcass characteristics. Treatments consisted of 0, 0.8, 1.6, or 2.4% CaO inclusion in the diet (DM basis), with CaO replacing limestone. Steers were slaughtered at a target BW of approximately 641 kg. In Exp. 2, 4 steers (initial BW = 288 ± 3 kg) were randomly allotted to the same diets in a 4 × 4 Latin square design (14-d periods) to determine the effects of CaO on ruminal pH, VFA, and nutrient digestibility. Statistical analyses were conducted using the MIXED procedure of SAS. Inclusion of CaO at 0.8, 1.6, and 2.4% increased ADG by 5.0, 3.9, and 0%, respectively, compared to 0% CaO (quadratic; P = 0.03). Intake was linearly decreased (P = 0.04) and G:F was linearly increased (P = 0.02) by CaO inclusion. Dressing percentage increased as CaO increased from 0 to 1.6% and then decreased for 2.4% CaO (quadratic; P < 0.01). In Exp. 2, steers fed 0% CaO had the greatest prefeeding ruminal pH, steers fed 0 and 0.8% CaO exhibited the most rapid postfeeding decline in ruminal pH, and steers fed 2.4% CaO exhibited a relatively stable ruminal pH throughout the 24-h period (treatment × time; P ≤ 0.01). Acetate, butyrate, and total VFA concentrations increased linearly (P ≤ 0.05) at 0, 3, 6, and 12 h postfeeding with increasing CaO. Propionate at 3 h postfeeding increased from 0 to 1.6% CaO and decreased from 1.6 to 2.4% CaO (quadratic; P = 0.10). Urine pH increased linearly (P ≤ 0.01) while urine output and urine ammonia decreased linearly (P ≤ 0.05) as CaO inclusion increased. Apparent NDF digestibility tended to increase (P = 0.07) and ADF digestibility did (P = 0.01) increase linearly with increasing concentrations of CaO. In conclusion, CaO improved ruminal pH variation, increased fiber digestibility, and decreased metabolic acid load in cattle fed 60% DDGS-based diets. Inclusion of CaO up to 1.6% was effective in improving performance of feedlot cattle.

The objective of these experiments was to determine adaptation by ruminants to dietary sulfur. In Exp. 1, lambs (n = 54; BW = 33.6 ± 0.4 kg) were allotted to 3 treatments: 1) 0% added dietary S (0%S), 2) 0.2% added dietary S (0.2%S), or 3) 0.4% added dietary S (0.4%S). Sulfur was added to the diet as Na(2)SO(4). Lambs fed the 0.2%S and 0.4%S diets had greater (P < 0.01) ADG and G:F compared to those fed the 0%S diet. There was time × diet interaction (P < 0.01) on ruminal hydrogen sulfide gas (H(2)S) concentrations. Ruminal H(2)S was not detected in lambs fed 0%S at any time. Ruminal H2S were not affected (P > 0.19) by diet on d 1 or 8; however, H(2)S were greater (P < 0.01) for lambs fed 0.2%S and 0.4%S than for lambs fed 0%S on d 15, 22, and 29 (0.2% was 931, 846, and 1,131 mg/L and 0.4% was 975, 737, and 1,495 mg/L on d 15, 22, and 29, respectively). These data suggest it takes at least 29 d for peak ruminal H(2)S to occur after exposure to Na(2)SO(4). In Exp. 2, lambs (n = 66; BW = 51.1 ± 0.4 kg) were allotted to 3 treatments: 1) 60% dried distillers grains with solubles (DDGS), 2) corn-based diet with Na(2)SO(4), or 3) corn-based diet with H(2)SO(4). All diets were formulated to contain 0.4%S. Lambs fed Na(2)SO(4) had greater (P < 0.05) ADG, DMI, and G:F than those fed H(2)SO(4) or 60% DDGS. A time × diet interaction occurred (P < 0.01) for ruminal H(2)S. There was no difference (P = 0.82) in H(2)S of lambs on d 1. However, at d 14 and 27 lambs fed supplemental Na(2)SO(4) had the lowest H(2)S concentrations while lambs fed 60% DDGS had the greatest (P < 0.01 on both d); lambs fed H(2)SO(4) were intermediate and different than both. These data suggest that at the same dietary S concentration, acidic S sources increased H(2)S and decreased DMI and ADG. In Exp. 3, Angus cross calves (n = 72; average initial BW = 324 ± 3 kg) were allotted to 3 treatments: 1) corn-based control d 0 through 85 (0%DDGS), 2) gradual step up to 60% DDGS diet (20% DDGS d 0 to 6, 40% DDGS d 7 to 13, 50% DDGS d 14 to 20, and 60% DDGS d 21 to 85; Step-up), or 3) 60% DDGS d 0 to 85 (60%DDGS). Overall, cattle fed 0%DDGS had increased (P < 0.05) DMI and ADG compared with those fed 60%DDGS or Step-up, and G:F was not affected (P = 0.42) by dietary treatment. On d 14, ruminal H(2)S concentrations were greater (P < 0.01) for cattle fed 60%DDGS and Step-up than for those fed 0%DDGS, and they did not differ (P ≥ 0.22) between DDGS-containing diets. These data illustrate that source of S impacts ruminal S metabolism and that S from DDGS is more readily reduced than S from Na(2)SO(4) or H(2)SO(4).

Mature Angus-cross beef cows (n = 228) were used to evaluate effects of prepartum dietary energy source on postnatal growth and carcass composition of progeny in a 2-yr study. Starting at approximately 160 d of gestation, cows were fed diets consisting of 1 of 3 primary energy sources: grass hay (HY), corn (CN), or dried corn distillers grains with solubles (DG). The CN and DG diets were limit-fed to achieve similar energy intakes as cows fed HY. Following parturition, cows were fed a common diet and managed as a single group. Calves were weaned at an average of 185 ± 6 d of age and backgrounded for 28 d. A subset of progeny (n = 134) was individually fed a common finishing diet until slaughter, when each calf reached 1.2 ± 0.05 cm of backfat. A glucose tolerance test (GTT) was conducted in year 2 on 4 calves/treatment after 41 and 111 d on the finishing diet (DOF). Calf birth weights were greater (P = 0.002) in calves from cows fed CN and DG than calves from cows fed HY, and weaning BW (P = 0.08) was less for calves from cows fed HY vs. CN. Receiving BW, final BW, and HCW did not differ (P ≥ 0.16) among treatments. No difference (P ≥ 0.28) in ADG, morbidity, and mortality from birth to slaughter was observed among treatments. In response to a GTT, increased DOF resulted in greater (P ≤ 0.005) fasting insulin, faster glucose disappearance rate, and greater insulin:glucose area under the curve ratio. Glucose disappearance rate was greater (P = 0.01) in calves from cows fed CN than in calves from cows fed HY or DG. A greater initial insulin response (P = 0.005) was observed in calves from cows fed CN or DG than in calves from cows fed HY. Carcass traits used to measure yield grade did not differ (P ≥ 0.19) among treatments. Calves from dams fed CN had the lowest marbling score (P = 0.03) and intramuscular fat content (P = 0.07). These results indicate that prepartum maternal dietary energy source can alter fetal adipose tissue development and insulin sensitivity resulting in long-term effects on progeny's intramuscular fat deposition. Moreover, present findings suggest that increasing the number of days on a corn-based finishing diet increases insulin resistance in beef cattle.

Dried distillers grains with solubles (DDGS) can decrease rumen pH because of their inherent acidity. Two replicated 4 × 4 Latin square experiments were conducted with ruminally fistulated heifers to determine the effects of dietary inclusion and NaOH treatment of DDGS on rumen metabolism. In Exp. 1, dietary treatments were 0%, 20%, 40%, or 60% DDGS on a DM basis. The remainder of the diet was 15% corn silage, 20% vitamin-mineral supplement, and corn (to replace DDGS) on a DM basis. Dry matter intake decreased (linear; P < 0.01) with increasing dietary inclusion of DDGS. Rumen pH was less than 5.3 from 1.5 to 12 h after feeding regardless of dietary DDGS inclusion, and mean rumen pH tended to decrease (linear; P = 0.08) with increasing DDGS. Rumen fluid S(2-) and rumen H(2)S gas concentrations increased (P < 0.01) with increasing DDGS inclusion at all time points postfeeding. At 3 h after feeding, ruminal concentrations of acetate, propionate, and total VFA increased linearly (P < 0.04) with increasing dietary inclusion of DDGS. Acetate to propionate ratio (A:P) ranged from 0.97 to 1.25 and was not affected (P = 0.88) by diet over time. In Exp. 2, dietary treatments were 1) 25% DDGS inclusion, untreated, 2) 60% DDGS inclusion, untreated, 3) 25% DDGS inclusion, treated with 2% NaOH, and 4) 60% DDGS inclusion, treated with 2% NaOH. Dry matter intake decreased (P < 0.01) when 60% DDGS was included in the diet regardless of NaOH treatment. Mean rumen pH was greater (P < 0.01) when NaOH-treated DDGS was fed regardless of dietary inclusion level. There were interactions (P ≤ 0.06) of NaOH treatment by DDGS inclusion by time for mean H(2)S and S(2-) concentrations. These interactions occurred because the magnitude of the response to NaOH treatment was greater for the 60% DDGS diets than for the 25% DDGS diets only from 1.5 to 9 h postfeeding. There were no interactions (P > 0.05) of NaOH treatment by DDGS inclusion on VFA concentrations. Acetate concentration decreased (P = 0.04) in cattle fed 60% DDGS diets at 0 h, but at 3 h postfeeding it tended to increase (P = 0.06). Total lactate was less than 1.30 for all dietary treatments at all time points. Treating DDGS with 2% NaOH may increase rumen pH and decrease H(2)S, thereby alleviating polioencephalomalacia.

Two experiments were conducted to evaluate the effects of monensin and dried distillers grains with solubles (DDGS) on ruminal metabolism in 8 fistulated steers. In Exp. 1, treatments were (DM basis): 1) 0 mg monensin/kg diet DM, 2) 22 mg monensin/kg diet DM, 3) 33 mg monensin/kg diet DM, and 4) 44 mg monensin/kg diet DM. The remainder of the diet was 10% corn silage, 60% DDGS, 10% corn, and 20% mineral supplement that used ground corn as the carrier. There was no effect (P > 0.80) of dietary monensin inclusion on DMI. Increasing dietary monensin did not affect (P > 0.05) ruminal VFA concentrations or lactic acid concentrations. There was no effect (P > 0.15) of increasing dietary monensin concentration on ruminal hydrogen sulfide gas (H(2)S) and liquid sulfide (S(2-)) concentrations, or ruminal pH. In Exp. 2, treatments were arranged in a 2 × 2 factorial and contained (DM basis): 1) 0 mg monensin/kg diet DM + 25% DDGS inclusion, 2) 0 mg monensin/kg diet DM + 60% DDGS inclusion, 3) 44 mg monensin/kg diet DM + 25% DDGS inclusion, and 4) 44 mg monensin/kg diet DM + 60% DDGS inclusion. The remainder of the diet was 15% corn silage, corn, and 20% mineral supplement that used ground corn as a carrier. With 60% dietary DDGS inclusion, DMI decreased (P < 0.01) when compared with 25% DDGS inclusion. With 25% DDGS in the diet, 0 h postfeeding acetate concentration was decreased compared with when 60% DDGS was fed (P < 0.01). A similar response (P < 0.01) occurred for total VFA concentrations at 0 h postfeeding. However, at 3 and 6 h postfeeding, propionate concentrations increased (P ≤ 0.05) in cattle fed the 60% DDGS diets, regardless of monensin inclusion. This increase in propionate concentrations contributed to the increase (P = 0.03) in total VFA concentrations at 3 h postfeeding when 60% DDGS diets were fed. There was no interaction detected (P > 0.05) for H(2)S or S(2-) concentrations in Exp. 2. Feeding 60% DDGS diets increased mean H(2)S by 71% when compared with feeding 25% DDGS diets. Similar to the response observed for H(2)S, feeding 60% DDGS diets increased mean S(2-) by 64% when compared with feeding 25% DDGS diets. Although these studies did not show beneficial effects of monensin supplementation on ruminal pH, VFA, or H(2)S concentrations, adverse rumen conditions, notably low ruminal pH, when high DDGS diets were fed may have precluded the effects of monensin from being realized.

The objectives of this research were to determine the interaction of monensin and haylage supplementation for steers fed 60% dried distillers grains (DDGS) on 1) mineral status, performance, and carcass characteristics, and on 2) ruminal pH, H(2)S, and short-chain fatty acid concentrations. In Exp. 1, Angus-cross steers (n=168; BW=277 ± 67 kg) were blocked by BW and allotted in a 2 × 2 factorial arrangement of treatments to 24 pens. Dietary treatments were 1) 0 mg of monensin/kg of diet + 0% haylage, 2) 33 mg of monensin/kg of diet + 0% haylage, 3) 0 mg of monensin/kg of diet + 10% haylage, and 4) 33 mg of monensin/kg of diet + 10% haylage. The remainder of the diet was 60% DDGS, 10% corn silage, 15% supplement, and corn (either 5 or 15%) on a DM basis. When supplemented with 0 mg of monensin/kg of diet, added haylage increased ADG by 5.7%, whereas when supplemented with 33 mg of monensin/kg of diet, added haylage increased ADG by 13% (P < 0.01). No interactions of monensin and haylage were observed for DMI or G:F (P ≥ 0.36). Haylage inclusion increased (P < 0.01) DMI and decreased (P < 0.01) G:F. No interactions (P > 0.05) on plasma mineral concentrations were observed; however, over time, plasma Cu concentrations decreased (P < 0.01), whereas plasma ceruloplasmin and S concentrations increased (P < 0.01). There were no treatment effects (P ≥ 0.08) on carcass characteristics. Cattle fed the 60% DDGS diets benefitted from increased dietary forage, and the effects of monensin and forage were additive for ADG and final BW. In Exp. 2, ruminally fistulated steers (n=8; BW = 346 ± 34 kg) were used in a replicated 4 × 4 Latin square design and were randomly assigned to the diets used in Exp. 1. Haylage inclusion increased ruminal pH from 1.5 through 12 h postfeeding, and the effects of monensin supplementation were additive (P < 0.05). From 1.5 through 9 h postfeeding, steers fed 33 mg of monensin/kg of diet tended to have reduced (P ≤ 0.10) concentrations of H(2)S when compared with steers fed 0 mg of monensin/kg of diet. Acetate:propionate ratios at 6 h postfeeding were 0.94, 0.93, 1.29, and 1.35 for diets 1 to 4, respectively (P < 0.01); total lactate was decreased regardless of treatment (range: 0.94 to 1.42 µmol/mL). Sulfuric acid in DDGS, not ruminal short-chain fatty acids, may be responsible for the low rumen pH observed and may influence the maximum inclusion of DDGS in cattle diets. Monensin supplementation decreased H(2)S concentration and may decrease the risk of polioencephalomalacia for cattle fed high-DDGS diets., (© 2011 American Society of Animal Science. All rights reserved.)

Energy density in growing diets may affect carcass quality of cattle; however, few reports have described the impact of energy source. The objectives of this research were to determine effects of source [dried distillers grains with solubles (DDGS) vs. corn] and amount (limit-fed to gain 0.9 vs. 1.4 kg of BW/d) of energy during the growing phase on feedlot performance and marbling. Angus-cross steers (144 head) were blocked by BW (average initial BW = 252 ± 36 kg), allotted within each block to 8 pens (6 steers/pen, 24 pens total), and randomly assigned to 1 of 4 feeding systems in a 2 × 2 factorial arrangement of treatments: 1) 65% DDGS fed to gain 0.9 kg of BW/d, 2) 65% DDGS fed to gain 1.4 kg of BW/d, 3) 65% corn fed to gain 0.9 kg of BW/d, and 4) 65% corn fed to gain 1.4 kg of BW/d. Fecal grab samples were collected on d 52 of the growing phase to determine digestibility of DM, ADF, NDF, ether extract (EE), and CP. After the 98-d growing phase, all steers were fed the same finishing diet. Steers were slaughtered by pen when average BW within the pen was 544, 522, and 499 kg for the large, medium, and small BW blocks, respectively. Average daily gain and DMI differed (P<0.01) by design during the growing phase. Compared with the corn-based diets, digestibilities of DM, NDF, and EE were decreased (P<0.02) when DDGS-based diets were fed during the growing phase, whereas the digestibility of N was increased (P<0.01). The ADG was greatest (P=0.02) during the finishing phase for steers fed to gain 0.9 kg of BW/d initially, but source of energy during the growing phase did not affect (P=0.24) finishing phase ADG. Steers fed to gain 0.9 kg of BW/d during the growing phase also had less backfat (P=0.08), decreased USDA yield grades (P=0.03), and greater LM area (P<0.01) than steers fed to gain 1.4 kg of BW/d. There was an interaction between energy source and amount for marbling scores (P=0.02). Steers fed corn-based diets to gain 0.9 kg of BW/d during the growing phase had the most marbling, whereas those fed to gain 0.9 kg of BW/d on DDGS had the least marbling; the remaining feeding systems were intermediate. Overall ADG and DMI were affected (P < 0.06) by both source and amount of energy fed during the growing phase. Feeding the DDGS-based diet to achieve greater ADG during the growing phase increased marbling, whereas feeding the corn-based diet to increase ADG during the growing phase decreased marbling., (© 2011 American Society of Animal Science. All rights reserved.)