Effects of limit feeding corn or dried distillers grains with solubles at 2 intakes during the growing phase on the performance of feedlot cattle

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.     

Rumen protected fat in kline barley or corn diets for beef cattle: digestibility, physiological, and feedlot responses.

A rumen protected fat product composed of Ca salts of fatty acids (CAF) was evaluated in beef cattle diets. Dietary treatments in a metabolism trial (six steers, 251 +/- 15 kg) and Feedlot Trial 1 (15 individually fed heifers, 355 +/- 11 kg) consisted of 62.1% corn and 3.2% soybean meal (C), 32.6% corn and 33.1% Kline barley (CB), and 28.2% corn, 33.1% barley, and 4.5% CAF (CBF) on a DM basis. Apparent DM and OM digestibilities were higher (P less than .05) and NDF digestibility was lower (P less than .05) for C than for CB and CBF. Apparent ether extract digestibility was higher (P less than .01) for CBF than for CB. Retention of N was higher (P less than .05) for C than for CB and CBF. On d 42, Feedlot Trial 1 ruminal fluid acetate:propionate ratio was lower (P less than .01) for C than for CB and CBF, and the ratio was lower (P less than .01) for CB than for CBF. Treatments did not affect (P less than .10) ADG and DMI of heifers, but feed/gain was lower (P less than .05) for C than for CB and CBF, and feed/gain was higher (P less than .05) for CBF than for CB. In Feedlot Trial 2, steers and heifers were fed the C diet or a 57% corn, 21.4% peanut hull, 4.1% soybean meal, and 4.5% CAF diet (CF) on an ad libitum basis for 50 d. Ruminal fluid acetate and propionate were unaffected (P greater than .10) by dietary treatments. Cattle ADG tended to be lower (P greater than .10), DMI was lower (P less than .05), and feed/gain tended to be improved (P greater than .10) for CF compared with C. Kline barley has potential as a feed grain for cattle, but CAF may not improve beef cattle performance, especially when diets contain barley.     

Brown midrib-3 corn silage improves digestion but not performance of growing beef steers

The brown midrib-3 (bm3) gene mutation has been incorporated into corn plants to potentially improve fiber digestibility. The objectives of this study were to determine the effect of bm3 corn silage on digestion and performance of growing beef steers and to determine whether limiting intake would further enhance fiber digestibility of bm3 corn silage. A bm3 hybrid and its isogeneic normal counterpart were harvested at three-quarters kernel milk line. Neutral detergent fiber, ADF, and ADL were 4.5, 6.9, and 1.9 units lower, respectively, and DM was 5.4 units higher for bm3 than for normal silage. In Trial 1, eight ruminally fistulated Angus crossbred steers (224 +/- 24 kg) were randomly assigned to a 2 x 2 factorial arrangement of treatments in a replicated 4 x 4 Latin square design. Steers had ad libitum feed access or were restricted to 80% of ad libitum intake of diets containing 86% normal corn silage (Control) or bm3 corn silage (BMCS). The remainder of the diets consisted of soybean meal, urea, monensin, vitamins, and minerals. Dry matter intake was greater (P < 0.01) for steers offered ad libitum access to BMCS than for those with ad libitum access to the Control diet. The BMCS treatment resulted in improved (P < 0.05) apparent total-tract digestibility of DM, OM, NDF, and ADF. Mean concentration of total VFA and molar proportions of acetate were increased (P < 0.05) by feeding BMCS. There tended to be a DMI x hybrid interaction (P = 0.16) for apparent total-tract digestibility of NDF. When diets were offered ad libitum, BMCS increased NDF digestibility by 10.5 percentage units compared with Control, but, when DMI was limited, BMCS increased NDF digestibility by 15.8 percentage units. In Trial 2, 128 steer contemporaries of those used in Trial 1 (245 +/- 13 kg) were offered ad libitum access to BMCS or Control diets as used in Trial 1. After a 112-d treatment period, concentrate in the diet was increased, and all steers were fed a common finishing diet. During the 112-d treatment period, steers receiving BMCS consumed 0.45 kg more DM/d (P < 0.05) and had similar ADG (P > 0.10), compared with those steers receiving the Control silage. This resulted in poorer (P < 0.01) feed efficiency for steers receiving BMCS. Finishing phase and overall performance of the steers was not different (P > 0.10) due to treatment. Although feeding BMCS in growth-phase diets resulted in increased daily DMI and improved digestibility of DM and fiber, it did not result in improved steer feedlot ADG compared with Control silage.     

Influence of genotype and diet on steer performance, manure odor, and carriage of pathogenic and other fecal bacteria. I. Animal performance

Although Brahman crosses constitute a large portion of US beef cattle, little information is available on their response to diverse feed resources compared with Bos taurus steers. Thus, the objectives were to evaluate genotype and diet effects on steer performance during the growing period and subsequent response to a high grain diet during the finishing period. Fifty-one steers [0 (15), 1/4 (20), 1/2 (7), and 3/4 Brahman (9), with the remaining proportion being MARC III] were allotted to 8 pens. Beginning on December 2, steers were individually fed chopped bromegrass hay (n = 26; DM = 85%, CP = 9.5%, ME = 2.19 Mcal/kg) or a corn silage-based diet (n = 25; DM = 51%, CP = 11.9%, ME = 2.75 Mcal/kg) for 119 d. All steers were then fed a high corn diet (DM = 79%, CP = 11.7%, ME = 3.08 Mcal/kg) to a target BW of 560 kg (176 d). Data were analyzed by ANOVA, with genotype, growing diet, and the 2-way interaction included. The interaction was not significant (P > 0.25). The MARC III and 1/2 Brahman steers weighed more (P < 0.01) than 1/4 or 3/4 Brahman steers initially and at the end of the growing period. Weight of bromegrass-fed (325 kg) steers was less than that of corn silage-fed (384 kg) steers at the end of the growing period. Steer ADG and intake of DM, CP, and ME were less (P = 0.087 to 0.001) for 1/4 and 3/4 Brahman than for 0 or 1/2 Brahman steers during growing, finishing, and total, but efficiency of gain did not differ (P > 0.10). Carcass weight, marbling score, quality grade (P < 0.05), and kidney fat (P = 0.06) differed among genotypes. Daily DMI (6.91 vs. 7.06 kg) was similar, but CP (0.66 vs. 0.84 kg) and ME (15.2 vs. 19.4 Mcal) intake of bromegrass fed was less (P = 0.001) than those of corn silage-fed steers. Values for DMI/gain (22.3 vs. 7.43 kg/kg), CP intake/gain (2.13 vs. 0.88 kg/kg), and ME intake/gain (48.8 vs. 20.4 Mcal/kg) were greater (P < 0.001) in bromegrass-fed than corn silage-fed steers. Over the total study, ADG was lower (0.96 vs. 1.01 kg), and DMI (7.82 vs. 7.19 kg), DMI/gain (8.21 vs. 7.10 kg/kg), and ME intake/gain (22.6 vs. 20.9 Mcal/kg) were greater (P < 0.05) in bromegrass-fed than in corn silage-fed steers. Carcass weight, dressing percent, adjusted backfat, and yield grade (P < 0.05) were greater for corn silage-fed than for bromegrass-fed steers. Feed intake and performance, but not efficiency, differed among these genotypes. Compensatory performance during finishing was insufficient to overcome reduced performance during the growing period.     

Effects of feeding growing cattle high-concentrate diets at a restricted intake on feedlot performance

Three trials were conducted to compare effects of restricted intake of high-concentrate diets vs ad libitum intake of corn silage diets during the growing phase on feedlot cattle performance. In Trial 1, 120 steers (initial BW, 246 kg) were fed 1) a corn silage-based diet ad libitum, 2) a high-moisture corn-corn silage-based diet with intake restricted to a level 20% less than that of the corn silage diet or 3) a high-moisture corn-based diet with intake restricted to a level 30% less than that of the corn silage diet. Steers fed the 20% restricted corn-corn silage-based diet tended (P = .07) to gain slower than those fed the corn silage or 30% restricted high-concentrate diet. Feed efficiency and diet digestibility were greatest for steers fed the 30% restricted-intake, high-concentrate diet (P less than .01). Performance of steers during the subsequent 118-d finishing period was not affected (P greater than .65) by source of energy during the growing period. In Trial 2, ADG of steers fed the 30% intake-restricted, high-concentrate diet was lower (P less than .01) than that of steers with ad libitum access to corn silage. During the 84-d growing period, steers fed supplemental blood meal had 8.3% greater gains and a 6% greater efficiency of feed use than those fed supplemental soybean meal (P less than .01). Monensin did not affect (P = .82) performance of steers fed 30% restricted-intake diets. During the 76-d finishing period, gains and feed conversion were improved (P less than .01) for steers fed the restricted-intake diet in the growing period compared with those given ad libitum access to corn silage. During the growing period in Trial 3, ADG of steers restricted-fed an all-concentrate diet were slightly greater (P less than .10) than ADG of those given ad libitum access to corn silage. Gains did not differ (P = .37) during the subsequent finishing period when steers were switched to 85 or 100% concentrate diets. We concluded that intake of all concentrate diets can be restricted to achieve gains equal to those of steers given ad libitum access to corn silage-based diets without detrimental effects on finishing performance.     

Methane emissions from feedlot cattle fed barley or corn diets

Methane emitted from the livestock sector contributes to greenhouse gas emissions worldwide. Understanding the variability in enteric methane production related to diet is essential to decreasing uncertainty in greenhouse gas emission inventories and to identifying viable greenhouse gas reduction strategies. Our study focused on measuring methane in growing beef cattle fed corn- or barley-based diets typical of those fed to cattle in North American feedlots. The experiment was designed as a randomized complete block (group) design with two treatments, barley and corn. Angus heifer calves (initial BW = 328 kg) were allocated to two groups (eight per group), with four cattle in each group fed a corn or barley diet. The experiment was conducted over a 42-d backgrounding phase, a 35-d transition phase and a 32-d finishing phase. Backgrounding diets consisted of 70% barley silage or corn silage and 30% concentrate containing steam-rolled barley or dry-rolled corn (DM basis). Finishing diets consisted of 9% barley silage and 91% concentrate containing barley or corn (DM basis). All diets contained monensin (33 mg/kg of DM). Cattle were placed into four large environmental chambers (two heifers per chamber) during each phase to measure enteric methane production for 3 d. During the backgrounding phase, DMI was greater by cattle fed corn than for those fed barley (10.2 vs. 7.6 kg/d, P < 0.01), but during the finishing phase, DMI was similar for both diets (8.3 kg/d). The DMI was decreased to 6.3 kg/d with no effect of diet or phase while the cattle were in the chambers; thus, methane emissions (g/d) reported may underestimate those of the feedlot industry. Methane emissions per kilogram of DMI and as a percentage of GE intake were not affected by grain source during the backgrounding phase (24.6 g/kg of DMI; 7.42% of GE), but were less (P < 0.05) for corn than for barley during the finishing phase (9.2 vs. 13.1 g/kg of DMI; 2.81 vs. 4.03% of GE). The results indicate the need to implement dietary strategies to decrease methane emissions of cattle fed high-forage backgrounding diets and barley-based finishing diets. Mitigating methane losses from cattle will have long-term environmental benefits by decreasing agriculture's contribution to greenhouse gas emissions.     

Combinations of alfalfa hay and wet corn gluten feed in limit-fed growing diets for beef cattle

Two experiments were conducted to evaluate the effects of alfalfa hay (AH) and wet corn gluten feed (WCGF) combinations on ADG and gain efficiency of cattle limit-fed growing diets. In Exp. 1, crossbred beef steers (n = 220; initial BW = 262 kg) were limit-fed diets consisting of steam-flaked corn and 40% WCGF (DM basis) with 0, 10, or 20% ground AH (0AH, 10AH, and 20AH, respectively). A fourth diet containing 20% ground AH and steam-flaked corn served as a control. All diets were fed once daily at 1.8% of BW (DM basis). Growing period ADG, gain efficiency, and dietary NE calculated from performance data decreased linearly (P < 0.01) with addition of AH to diets containing WCGF. Rate of DMI increased linearly (P < 0.05) with AH addition to diets containing WCGF. Following the growing period, steers were finished on a common diet offered ad libitum. Gain efficiencies during the finishing period were higher (P < 0.05) for steers fed the 20AH diet than for steers fed the control diet. In Exp. 2, crossbred beef heifers (n = 339; initial BW = 277 kg) were limit-fed diets containing steam-flaked corn with 10, 20, or 30% ground AH and 0, 40, or 68% WCGF in a 3 x 3 factorial arrangement, fed once daily at 1.6% of BW (DM basis). An AH x WCGF interaction occurred (P < 0.05) for growing period ADG and gain efficiency. Increasing AH or WCGF decreased cattle ADG, gain efficiency, and dietary NE with the exception of heifers fed 30AH/40WCGF, which had ADG that did not differ (P > 0.10) from that of heifers fed 20AH/0WCGF or 30AH/0WCGF, and which had greater gain efficiencies (P < 0.05) than heifers fed 30AH/0WCGF. Rate of DMI increased linearly (P < 0.01) with increasing AH and decreased linearly (P < 0.01) with increasing WCGF. Heifers were finished on diets containing 33% WCGF with 0 or 0.5% added urea (DM basis) offered ad libitum. Increasing WCGF in growing diets tended (linear, P < 0.10) to increase finishing ADG and gain efficiency, whereas increasing AH decreased (linear, P < 0.05) kidney, pelvic, and heart fat, and the percentage of carcasses grading USDA Prime. Urea tended to increase ADG (P < 0.10), but decreased (P < 0.04) the percentage of carcasses grading USDA Choice. Results suggest that the value of WCGF relative to steam-flaked corn in limit-fed growing diets might be improved in diets containing 30% AH relative to diets containing 10 or 20% AH.     

Neutral detergent fiber concentration in corn silage influences dry matter intake, diet digestibility, and performance of Angus and Holstein steers

Twelve Angus (237 +/- 13 kg) and twelve Holstein (235 +/- 15 kg) steers were used to determine whether corn silage-based diets with different NDF levels influence DMI to a similar extent in Angus and Holstein steers and as body weight of the steers increase. Steers were randomly assigned to individual slatted-floor pens and used in a crossover design consisting of six 14-d periods. Experimental diets contained corn silage from a normal hybrid (low-fiber; LF) and its male-sterile counterpart (high-fiber; HF) and were alternated each period. The LF and HF diets contained 33.8 and 50.8% NDF, respectively. The HF diet decreased (P < 0.01) overall steer mean DMI 14.0% relative to LF, with mean differences increasing as steers increased in BW (P < 0.01). Feeding the HF diet also reduced ADG by an average of 13.8% relative to the LF diet (P < 0.01). Holstein steers consumed 14.4% more DM and gained 14.3% faster (P < 0.01) than Angus steers. There was a fiber level x breed-type interaction (P = 0.08) for efficiency of gain. Angus steers receiving the HF diet had greater efficiency of gain than Angus steers consuming the LF diet; however, Holstein steers consuming the LF diet had greater efficiency of gain than those receiving the HF diet. The HF treatment reduced total-tract digestibility of DM and GE by 4.6 and 4.5%, respectively (P < 0.01), and decreased DE intake by 20.5% (P < 0.01) but increased apparent totaltract digestibility of NDF and ADF (9.4 and 8.4%, respectively; P < 0.01). Holstein steers had similar digestibility of DM and GE (P > 0.10) but had greater DE intake (P < 0.01) compared to Angus steers. There were fiber level x breed-type interactions for total-tract digestibility of NDF and ADF (P < 0.06). The difference in DM digestibility was negatively associated with the difference in DMI (r2 = 0.23; P < 0.01) for LF minus HF within Angus steers, but not within Holstein steers (P = 0.42). Total-tract digestibility of NDF and ADF was 4.1 and 3.4% lower for the HF diet but was only 1.1 and 0.6% lower for the LF diet when fed to Holstein compared to Angus steers. Results from this trial demonstrate that high-NDF corn silage-based diets reduced intake of both Angus and Holstein steers, and this reduction in DMI continued as steers increased in BW from 235 to 330 kg. Breed differences were also noted for digestible energy intake as influenced by fiber level.     

Effect of fat type and forage level on performance of finishing cattle.

Four trials were conducted to determine the effects of adding various levels and types of fat to dry-rolled corn (DRC) finishing diets containing 0 or 7.5% forage. In Trial 1, 88 yearling steers (mean BW = 352 +/- 38 kg) and 176 heifers (mean BW 316 +/- 15 kg) were blocked by sex and weight into four replications. Treatments were 0, 2, 4, or 6% (DM basis) bleachable fancy tallow (BT) fed with 0 or 7.5% (DM basis) forage. Addition of BT to the 7.5% forage diet had no effect on ADG or gain/feed (G/F). However, adding BT to the all-concentrate diet decreased ADG (linear, P < .01) and G/F (linear, P = .08). In Trial 2, 184 yearling steers (mean BW = 347 +/- 21 kg) and 144 heifers (mean BW 322 +/- 8 kg) were blocked by sex and weight into six replications. Fat treatments were 0% fat, 4% BT, or 4% animal-vegetable oil blend (A-V); each fat treatment was fed with 0 or 7.5% forage. Across forage levels, the addition of fat increased (P < .01) ADG and G/F for cattle fed DRC. In Trial 3, 18 crossbred wether lambs (mean BW = 44.4 +/- 2.5 kg) were fed DRC and 7.5% forage and allotted randomly to the same fat treatments fed in Trial 2. Apparent total tract fat digestibility increased (P < .01) with the addition of BT or A-V. In Trial 4, 40 crossbred wethers (mean BW = 25 +/- 4.1 kg) and 16 ewes (mean BW = 23 +/- 2.7 kg) were individually fed 7.5% forage diets containing 0, 1, 2, or 4% BT. Addition of BT increased (linear, P = .10) G/F. In summary, fat addition to DRC finishing diets fed to yearling cattle did not consistently affect gain/feed, feed intake, and ADG.     

Predicting growth and performance of Holstein steers

Refinements and additions were made to the growing cattle portion of the model of Fox et al. (1988) for predicting growth of Holstein steers. Based on observations of animal weight, DM intake (DMI), ADG, feed per gain (FPG) and diet ME, the modified model was tested on a database that included 299 feeding periods with Holstein steers fed in research trials over a period of 15 yr at Cornell University, the University of Minnesota and the University of Wisconsin. The modified model accounted for 93, 56 and 68% of the variation in DM intake, daily gain and feed required per unit gain, respectively. Averaged over all 299 periods in the database, the error in predicting DM intake, daily gain and feed required per unit gain was 1%, 4% and 2%, respectively. Analysis of residuals indicated that ME level did not influence the difference between predicted and observed values for DMI, ADG and FPG. Residuals analysis indicated that BW did not influence the difference between predicted and observed values for ADG and FPG but DMI of heavier cattle was overpredicted (P less than .01). These results indicated that the 8% increase in DMI for cattle over 318 kg was not warranted for the Holstein steers in this database, which were predominantly less than 15 mo at slaughter. The results of the validation indicate that this model accurately predicted performance of Holstein steers.     

Effect of grain processing degree on intake, digestion, ruminal fermentation, and performance characteristics of steers fed medium-concentrate growing diets

Three trials were conducted to evaluate the effects of degree of barley and corn processing on performance and digestion characteristics of steers fed growing diets. Trial 1 used 14 (328 +/- 43 kg initial BW) Holstein steers fitted with ruminal, duodenal, and ileal cannulas in a completely randomized design to evaluate intake, site of digestion, and ruminal fermentation. Treatments consisted of coarsely rolled barley (2,770 microm), moderately rolled barley (2,127 microm), and finely rolled barley (1,385 microm). Trial 2 used 141 crossbred beef steers (319 +/- 5.5 kg initial BW; 441 +/- 5.5 kg final BW) fed for 84 d in a 2 x 2 factorial arrangement to evaluate the effects of grain source (barley or corn) and extent of processing (coarse or fine) on steer performance. Trial 3 investigated four degrees of grain processing in barley-based growing diets and used 143 crossbred steers (277 +/- 19 kg initial BW; 396 +/- 19 kg final BW) fed for 93 d. Treatments were coarsely, moderately, and finely rolled barley and a mixture of coarsely and finely rolled barley to approximate moderately rolled barley. In Trial 1, total tract digestibilities of OM, CP, NDF, and ADF were not affected (P > or = 0.10) by barley processing; however, total tract starch digestibility increased linearly (P < 0.05), and fecal starch output decreased linearly (P < 0.05) with finer barley processing. In situ DM, CP, starch disappearance rate, starch soluble fraction, and extent of starch digestion increased linearly (P < 0.05) with finer processing. In Trial 2, final BW and ADG were not affected by degree of processing or type of grain (P > or = 0.13). Steers fed corn had greater DMI (P = 0.05) than those fed barley. In Trial 3, DMI decreased linearly with finer degree of processing (P = 0.003). Gain efficiency, apparent dietary NEm, and apparent dietary NEg increased (P < 0.001) with increased degree of processing. Finer processing of barley improved characteristics of starch digestion and feed efficiency, but finer processing of corn did not improve animal performance in medium-concentrate, growing diets.     

Effects of dry, wet, and rehydrated corn bran and corn processing method in beef finishing diets

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

Effect of nutrition, age and size on compensatory growth in two breeds of steers

Compensatory gain in cattle was studied to determine if age, previous rate of gain or size were factors of importance. A factorial experiment was conducted with growing diet regimen (control vs restricted), age [spring-born (older) vs fall-born (younger)] and breed (Angus vs Charolais) as the factors. During a growing phase, the two diets, (control = dehydrated alfalfa pellets; restricted = cubed grass-alfalfa hay, cottonseed hulls and soybean meal) were fed to both the older and younger steers of each breed to provide groups of similar age but different weights (growing regimen within age) and groups of similar weights but different ages (older-restricted vs younger-controls) at the time at which the steers were switched to a high concentrate diet. Interactions of breed with age and previous growing regimen diet on digestibility of some nutrients in the finishing diet were evident. During the growing phase, control steers averaged .72 kg/d gain, whereas the restricted steers averaged .25 kg/d. The older-restricted steers compensated (P less than .05) from 30 to 120 d after the beginning of the feedlot phase compared with older-control steers. Rates of gain of younger steers were intermediate to those of the older steers throughout the finish phase and were not influenced by growing diet, except on d 30. Rate of gain during the growing phase was negatively correlated (P less than .05) with rate of gain during the finishing phase (60 to 120 d). Within breed, weight at the beginning of the feedlot phase also was negatively correlated with gain during the finishing phase. Skeletal growth was reduced (P less than.05) by the restricted diet during the growing phase, and small compensation (P greater than .05) was observed during the finishing phase. Feed/gain for restricted steers was slightly lower (P greater than .05) than control steers. Younger steers were more efficient (P less than .05) overall in converting dry matter to gain, due to the relatively shorter growing phase when compared with the older steers. These data indicate that both previous gain and weight upon realimentation are influential on compensatory growth.     

Effects of a return chewing gum/packaging material mixture on in situ disappearance and on feed intake, nutrient digestibility, and ruminal characteristics of growing steers

In situ and in vivo digestibility experiments were conducted to determine the acceptability, digestibility, and safety of a return chewing gum/packaging (G/P) material mixture when fed to steers. In the in situ experiment, both ruminal and intestinal disappearances were measured. Two ruminally and duodenally cannulated steers, which were given free access to alfalfa hay (AH), were used in this study. Duplicate Dacron bags containing the G/P were incubated in the rumen for 0, 3, 6, 12, 24, and 48 h. After ruminal incubation, the 12-, 24-, and 48-h bags were placed in the duodenum and collected in the feces to determine intestinal disappearance. In situ ruminal DM disappearance was greater than 70% for all substrates tested at 0 h, indicating high solubility of the substrates in water, and began to reach a plateau after 12 h of incubation. Intestinal in situ disappearance was not different (P>.25) from zero. In the digestion trial, four ruminally cannulated steers (337+/-21.3 kg BW; mean +/- SD) were used in a 4x4 Latin square design with the following treatments: 0) 50% corn (C), 50% AH; 10) 45% C, 45% AH, 10% G/P; 20) 40% C, 40% AH, 20% G/P; 30) 35% C, 35% AH, 30% G/P. Steers fed G/P-containing diets had greater (P<.01) DMI than the control steers. Increasing the G/P resulted in a linear (P<.05) increase in DMI. Apparent DM digestibility tended to be higher (P<.10) for the G/P-containing diets than for the control. A quadratic effect (P<.05) on digestible DMI was observed, with greater (P<.01) digestible DMI values for G/P-containing diets (4.8 vs. 5.8 kg/d). Digestible organic matter and total nonstructural carbohydrate intakes followed trends similar to those of DM. Apparent aluminum digestibility of G/P-containing diets was not different (P>.13) from zero. The level of G/P in the diet had no effect (P>.2) on total VFA concentration or ruminal pH. There was a linear decrease (P<.01) in the molar percentage of isobutyrate and isovalerate in addition to a linear increase (P<.01) in butyrate and valerate with increasing levels of G/P. There was a quadratic effect (P<.01) on molar proportions of acetate and propionate and on the acetate:propionate ratio. Results of both experiments suggest that G/P may be fed to safely replace up to 30% of corn-alfalfa hay diets for growing steers with advantages in improving DMI and digestibility.     

Value of sunflower seed in finishing diets of feedlot cattle

The value of sunflower seed (SS) in finishing diets was assessed in two feeding trials. In Exp. 1, 60 yearling steers (479 +/- 45 kg) were fed five diets (n = 12). A basal diet (DM basis) of 84.5% steam-rolled barley, 9% barley silage, and 6.5% supplement was fed as is (control), with all the silage replaced (DM basis) with rolled SS, or with grain:silage mix replaced with 9% whole SS, 14% whole SS, or 14% rolled SS. Liver, diaphragm, and brisket samples were obtained from each carcass. In Exp. 2, 120 yearling steers (354 +/- 25 kg) were fed corn- or barley-based diets containing no SS, high-linoleic acid SS, or high-oleic acid SS (a 2 x 3 factorial arrangement, n = 20). Whole SS was included at 10.8% in the corn-based and 14% in the barley-based diets (DM basis). In Exp. 1, feeding whole SS linearly increased DMI (P = 0.02), ADG (P = 0.01), and G:F (P = 0.01). Regression of ME against level of whole SS indicated that SS contained 4.4 to 5.9 Mcal ME/kg. Substituting whole for rolled SS did not significantly alter DMI, ADG, or G:F (8.55 vs. 8.30 kg/d; 1.36 vs. 1.31 kg; and 0.157 vs. 0.158, respectively). Replacing the silage with rolled SS had no effect on DMI (P = 0.91) but marginally enhanced ADG (P = 0.10) and improved G:F (P = 0.01). Dressing percent increased linearly (P = 0.08) with level of SS in the diet. Feeding SS decreased (P < 0.05) levels of 16:0 and 18:3 in both diaphragm and subcutaneous fats, and increased (P = 0.05) the prevalence of 18:1, 18:2, cis-9,trans-11-CLA and trans-10,cis-12-CLA in subcutaneous fat. In Exp. 2, barley diets supplemented with high-linoleic SS decreased DMI (P = 0.02) and ADG (P = 0.007) by steers throughout the trial, whereas no decrease was noted with corn (interaction P = 0.06 for DMI and P = 0.01 for ADG). With barley, high-linoleic SS decreased final live weight (554 vs. 592 kg; P = 0.01), carcass weight (329 vs. 346 kg; P = 0.06), and dressing percent (58.5 vs. 59.4%; P = 0.04). Steers fed high-linoleic SS plus barley had less (P < 0.05) backfat than those fed other SS diets. No adverse effects of SS on liver abscess incidence or meat quality were detected. Although they provide protein and fiber useful in formulating finishing diets for cattle, and did improve performance in Exp. 1, no benefit from substituting SS for grain and roughage was detected in Exp. 2. Because of unexplained inconsistencies between the two experiments, additional research is warranted to confirm the feeding value of SS in diets for feedlot cattle.     

Influence of dietary manganese on performance, lipid metabolism, and carcass composition of growing and finishing steers

A study was conducted to determine the effect of dietary Mn on performance of growing and finishing steers, and to evaluate the effect of pharmacological concentrations of Mn on lipid metabolism and subsequent carcass quality in steers. One hundred twenty Angus cross steers were blocked by BW and origin and assigned randomly to one of six treatments (four replicate pens per treatment) providing 0 (control), 10, 20, 30, 120, or 240 mg of supplemental Mn/kg of DM from MnSO4. Steers were fed a corn silage-based growing diet for 84 d, and then switched to a corn-based finishing diet for an average of 112 d. The control growing diet analyzed 29 mg of Mn/kg of DM, whereas the control finishing diet analyzed 8 mg of Mn/kg of DM. Jugular blood samples were obtained on d 56 of the growing and finishing phase for plasma Mn and glucose analysis. Final BW, DMI, ADG, and G:F did not differ (P = 0.38 to P = 0.98) across treatments during growing and finishing phases. Plasma Mn concentrations were not affected by treatment; however, liver and LM Mn at slaughter increased linearly (P = 0.02 and 0.002, respectively) with increasing dietary Mn. Plasma glucose concentrations did not differ (P = 0.90) among treatments. Serum nonesterified fatty acid concentrations tended (P = 0.10) to decrease linearly with increasing dietary Mn on d 56 of the finishing phase. Longissimus muscle lipid concentration was affected quadratically (P = 0.08) by dietary Mn. Muscle lipid seemed to increase slightly when steers were fed 30 or 120 mg of Mn/kg of DM, but decreased with the addition of 240 mg of Mn/kg of DM. Carcass characteristics were not affected by dietary Mn. Manganese concentrations of 29 and 8 mg/kg of DM in the growing and finishing diets, respectively, were adequate for maximizing performance of growing and finishing steers in this experiment. Supplementing physiological or pharmacological concentrations of Mn affected lipid metabolism; however, this did not result in altered carcass characteristics.     

Feeding value of coconut alcohol bottoms-bottoms for feedlot cattle

Six crossbred steers (274 kg) with "T" cannulas in the rumen, proximal duodenum (6 cm from the pyloric sphincter) and distal ileum (20 cm from the ileal-cecal valve) were used in a crossover experiment to evaluate the feeding value of coconut alcohol bottoms-bottoms (CABB) in a finishing diet for feedlot steers. Dietary treatments consisted of a steam-rolled barley-based finishing diet supplemented with or without 6% CABB. The CABB was blended first with the steam-rolled barley portion of the diet prior to adding the other dietary ingredients. Ruminal digestion of ADF and N was not affected (P greater than .10) by CABB supplementation. Added CABB decreased total tract digestibility of OM, ADF, lipid and DE by 5.65 (P less than .01), 29.4 (P less than .05), 57.4 (P less than .01) and 5.65%, respectively. Adjusting for constituent passage of the basal diet, estimated total tract digestibility of OM, DE and lipid of the supplemental CABB was 1.1, -.23 and 16.4%, respectively. CABB essentially has no feeding value in finishing diets for cattle.     

Grain source and processing in diets containing varying concentrations of wet corn gluten feed for finishing cattle

Two experiments were conducted to evaluate combinations of wet corn gluten feed (WCGF) and barley, as well as the particle size of dry-rolled barley and corn, in finishing steer diets containing WCGF. In Exp. 1, 144 crossbred steers (initial BW = 298.9 +/- 1.4 kg) were used to evaluate barley (0.566 kg/L and 23.5% NDF for whole barley) and WCGF combinations in finishing diets containing 0, 17, 35, 52, or 69% WCGF (DM basis), replacing barley and concentrated separator byproduct. A sixth treatment consisted of corn (0.726 kg/L and 11.1% NDF for whole corn), replacing barley in the 35% WCGF treatment. In Exp. 2, 144 crossbred steers (initial BW = 315.0 +/- 1.5 kg) were used to evaluate coarse or fine, dry-rolled barley or corn (0.632 and 0.699 kg/L; 26.6 and 15.9% NDF for whole barley and corn, respectively) in finishing diets containing WCGF. A factorial treatment design was used; the factors were grain source (corn or barley) and degree of processing (coarse or fine). The diets contained 50% WCGF, 42% grain (corn or barley), 5% alfalfa hay, and 3% supplement (DM basis). In Exp. 1, DMI and ADG responded quadratically (P < or = 0.03), peaking at 35 and 52% WCGF, respectively. The efficiency of gain was not affected (P > or = 0.42) by dietary treatment. Steers fed dry-rolled corn and 35% WCGF had heavier HCW, lower DMI, greater ADG, increased G:F, increased s.c. fat thickness at the 12th rib, and greater yield grades compared with steers fed dry-rolled barley and 35% WCGF (P < or = 0.04). The apparent dietary NEg was similar among the barley and WCGF combinations (P > or = 0.51); however, the corn and 35% WCGF diet was 25% more energy dense (P < 0.001) than was the barley and 35% WCGF diet. In Exp. 2, no grain x processing interactions (P > or = 0.39) were observed. Particle size was 2.15 and 2.59 mm for fine- and coarse-rolled barley and was 1.90 and 3.23 mm for fine- and coarse-rolled corn. Steers fed a combination of corn and WCGF had increased ADG, greater G:F, heavier HCW, larger LM area, more s.c. fat thickness at the 12th rib, greater yield grades, increased marbling, and more KPH compared with steers fed a combination of barley and WCGF (P < or = 0.03). Fine-rolling of the grain increased fat thickness (P = 0.04). The addition of WCGF to the barley-based diets increased DMI and gain. Decreasing grain particle size did not greatly affect performance of the steers fed the 50% WCGF diets; however, carcasses from the steers fed the fine-rolled grain contained more fat.     

Effects of restricted versus conventional dietary adaptation on feedlot performance,carcass characteristics,site and extent of digestion,digesta kinetics,and ruminal metabolism

Three experiments were conducted to determine effects of restricting intake of the final finishing diet as a means of dietary adaptation compared with diets increasing in grain over a period of 20 to 22 d on overall cattle performance, carcass characteristics, digestibility, digesta kinetics, and ruminal metabolism. In Exp. 1, 84 Angus x Hereford yearling steers (initial BW = 418 +/- 29.0 kg) were fed for 70 d. Restricting intake during adaptation had no effect (P > 0.10) on overall ADG:DMI, but decreased (P < 0.05) DMI compared with ad libitum access to adaptation diets, which resulted from differences during the initial 28 d of the experiment. In Exp. 2, 150 mixed crossbred steer calves (initial BW = 289 +/- 22.9 kg) were fed for an average of 173 d. Restricting intake decreased (P < 0.01) overall daily gain (1.51 vs 1.65 kg/d) and DMI (8.68 vs 9.15 kg/d) compared with ad libitum fed steers; however, ADG:DMI was not influenced (P > 0.10) by adaptation method. Experiment three used eight ruminally and duodenally fistulated steers (initial BW = 336 +/- 20 kg) in a completely random design. Total tract digestibility, digesta kinetics and ruminal metabolism were determined. Restricting intake reduced (P < 0.10) daily DMI variation from d 1 through 7, 8 through 14, and 22 through 28 compared with ad libitum feeding of three adaptation diets. Restricted steers had reduced (adaptation method x period interaction, P < 0.05) intakes and fecal excretions of ADF and greater OM digestibilities on d 4 through 7, 11 through 14, and 18 through 21. Digesta kinetics and ruminal metabolism were generally not affected (P > 0.10) by adaptation method. Our results suggest that restricted-feeding of the final diet as a means of dietary adaptation can be used in finishing cattle with few problems from acidosis or related intake variation. In light-weight steers (Exp. 2), disruptions in intake during the adaptation period might have resulted in restriction for an extended period, which decreased (P < 0.01) hot carcass weight compared with calves fed ad libitum. Effects of limit feeding during the initial 28 d of the feeding period on site and extent of digestion, digesta kinetics, and ruminal metabolism were minimal, supporting few differences in performance across the finishing period for yearling cattle.     

Influence of pressed beet pulp and concentrated separator by-product on intake, gain, efficiency of gain, and carcass composition of growing and finishing beef steers

The objectives of this experiment were to determine a NE value for pressed beet pulp and the value of concentrated separator by-product (de-sugared molasses) as a ruminal N source in growing and finishing diets for beef cattle. One hundred forty-four cross-bred beef steers (282 +/- 23 kg of initial BW) were used in 2 experiments (growing and finishing). A randomized complete block design was used, with a 3 x 2 factorial arrangement of treatments (level of pressed beet pulp and inclusion of concentrated separator by-product) for both studies. Steers were blocked by BW and allotted randomly to 1 of 6 treatments. In the growing study, the control diet contained 49.5% corn, 31.5% corn silage, 10.0% alfalfa hay, and 9.0% supplement (DM basis). Pressed beet pulp replaced corn at 0, 20, or 40% of dietary DM, and concentrated separator by-product replaced corn and urea at 10% of dietary DM. The growing study lasted for 84 d. Initial BW was an average of 2-d BW after a 3-d, restricted (1.75% of BW) feeding of 50% alfalfa hay and 50% corn silage (DM basis), and final BW was an average of 2-d BW after a 3-d, restricted (1.75% of BW) feeding of 31.5% corn silage, 10.0% alfalfa hay, 25.0% dry-rolled corn, 20.0% pressed beet pulp, 5.0% concentrated separator by-product, and 8.5% supplement (DM basis). After the growing study, the steers were weighed (415 +/- 32 kg), rerandomized, and allotted to 1 of 6 finishing diets. The control diet for the finishing study included 45% dry-rolled corn, 40% high-moisture corn, 5% brome hay, 5% pressed beet pulp, and 5% supplement. Pressed beet pulp replaced high-moisture corn at 5.0, 12.5, and 20.0% of the dietary DM, and concentrated separator by-product replaced high-moisture corn and supplement at 10.0% of diet DM. Steers were slaughtered on d 83 or 98 of the study. In the growing study, the addition of pressed beet pulp to growing diets linearly decreased (P = 0.001) DMI and ADG and inclusion of 10% concentrated separator by-product decreased (P = 0.001) G:F. Increased levels of pressed beet pulp in the finishing diets caused a linear decrease (P = 0.001) in ADG and tended (P = 0.06 and 0.07 for kg/d and % of BW, respectively) to quadratically decrease DMI, whereas addition of concentrated separator by-product increased (P = 0.02 and 0.001 for kg/d and % of BW, respectively) DMI. Apparent NEg of pressed beet pulp was 94.2% of that of corn in the growing study and 81.5% of that of corn in the finishing study.