Effect of sugar beet–pulp concentration during grain adaptation and in finishing diets with different corn processing methods on performance and carcass characteristics1

The Professional Animal Scientist 30 (2014):318–326

©2014 American Registry of Professional Animal Scientists

Effect of sugar beet–pulp concentration during grain

adaptation and in finishing diets with different corn processing methods on performance and carcass characteristics1 C. A. Nichols,*2 C. J. Schneider,*3 K. H. Jenkins,† G. E. Erickson,* S. A. Furman,† and M. K. Luebbe†4 *Department of Animal Science, University of Nebraska–Lincoln, Lincoln 68583-0908; and †University of Nebraska Panhandle Research and Extension Center, Scottsbluff 69361

ABSTRACT Two experiments evaluated the use of wet beet pulp (BP) in feedlot diets. In Exp. 1, feeding 0, 10, or 20% wet BP (DM basis) in either dry-rolled corn or steam-flaked corn finishing diets was evaluated using 432 steers (BW = 314 ± 25 kg) in a randomized block design with a 2 × 3 factorial treatment structure (n = 6 replications per treatment). No corn processing × BP interaction was detected (P > 0.05) for finishing performance and carcass data. Final BW, DMI, and ADG decreased linearly (P < 0.01) with

1 A contribution of the University of Nebraska Agricultural Research Division, supported in part by funds provided through the Hatch Act. 2 Current address: 1534 Ivanhoe Rd., Ely, IA 52227. 3 Current address: 2043 South St. Clair Street, Wichita, KS 67213. 4 Corresponding author: [email protected]

increasing concentration of BP; however, G:F was not different (P = 0.49) among BP concentrations. In Exp. 2, steers (n = 232; BW = 326 ± 14.5 kg) were used in a randomized block design to determine the effect of adapting steers to finishing diets using BP (n = 6 replications per treatment). Alfalfa-hay inclusion decreased as dry-rolled corn increased in the control treatment. Beet-pulp adaptation diets included a low-BP treatment or a high-BP treatment in which both BP and alfalfa were decreased as dry-rolled corn increased. After the 22-d adaptation period, steers were fed a common diet until slaughter. Gain and G:F were not different (P > 0.19) among treatments during grain adaptation. However, steers adapted using the high-BP and low-BP treatments tended (P = 0.07) to have greater ADG compared with the control throughout the entire finishing period. In summary, there was no BP × corn processing interaction. Replacing up to 50% of alfalfa with BP during grain adaptation is a suitable alternative.

Key words: beet pulp, corn processing, feedlot cattle, grain adaptation

INTRODUCTION Interest in using alternative feed sources has intensified because of the increase in grain prices. One feed resource that has been evaluated as a possible corn replacement is beet pulp. Wet beet pulp (24% DM, 9.5% CP, and 44% NDF) is a by-product that is produced during the extraction of sugar from sugar beets (Bauer et al., 2007). Although the availability of beet pulp may be limited by region, some feedlots are in close proximity and able to incorporate beet pulp into their beef-cattle diets. The fiber fraction of sugar-beet pulp is highly digestible and has been shown to be a very effective corn-silage substitute in growing diets (Rush et al., 1992; Park et al., 2000). Results from finishing research with beet pulp replacing corn (dry rolled or high moisture) indicate

beet pulp decreases finishing performance (Weichenthal et al., 1993; Park et al., 2001; Bauer et al., 2007). Data are limited on how corn processing methods interact with the feeding of beet pulp. Therefore, a feeding experiment was conducted to determine the effects of feeding different concentrations of beet pulp in combination with dry-rolled corn or steam-flaked corn. Adaptation of cattle to highconcentrate diets is an important period that may influence feedlot performance and health (Brown et al., 2006) for the entire finishing period. The low energy density and bulky nature of forages make them difficult to store, process, mix, and deliver to cattle in comparison to grain. Strategies that reduce or eliminate the use of forages to adapt cattle to finishing diets could potentially reduce the forage needs of a feedlot by 35 to 40%, which may result in decreased cost of gain and logistics within the feedlot (MacDonald and Luebbe, 2012). Limited research has evaluated the use of beet pulp as a forage replacement in grain adaption programs. Therefore, a second experiment was conducted to compare grain adaption programs using beet pulp to traditional grain adaption with alfalfa hay on finishing performance and carcass merit.

MATERIALS AND METHODS All procedures involving animal care and management were approved by the University of Nebraska’s Institutional Animal Care and Use Committee.

Exp. 1 Beet-Pulp Inclusion and Corn Processing Method A total of 432 yearling British × Continental steers (initial BW = 314 ± 25 kg) were used in an experiment conducted at the University of Nebraska–Lincoln Panhandle Research and Extension Center feedlot located near Scottsbluff, Nebraska. A randomized block design was used with a 2 × 3 factorial treatment structure with 3 BW blocks (n = 144 steers in each of the light, medium,

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and heavy BW block). Steers were assigned randomly to 36 pens (12 steers per pen) with pen serving as the experimental unit. The first factor was corn processing method, which consisted of either steam-flaked corn (SFC) or dry-rolled corn (DRC), and the second factor was concentration of wet-beet-pulp inclusion (0, 10, or 20% DM basis). Two weeks before the start of the experiment, steers were vaccinated with an infectious bovine rhinotracheitis, parainfluenza-3, bovine viral diarrhea virus, bovine respiratory syncytial virus modified live virus vaccine (Bovi-Shield Gold; Pfizer Animal Health, New York City, NY), vaccinated with a Clostridium chauvoei, C. septicum, C. novyi, C. sordelli, C. perfringens types C and D bacterin toxoid (Vision 7; Merck Animal Health, De Soto, KS), and treated with Ivomec (Ivomec; Merial, Duluth, GA) for internal and external parasite control. Steers were limit fed (2% of BW) a 50% ground alfalfa hay, 50% distillers grains (DM basis) diet for 5 d before the initiation of the experiment in an effort to reduce variation in gut fill at time of weighing (Klopfenstein, 2011). Steers were individually weighed using a hydraulic squeeze chute with load cells mounted on the chute (Silencer, Moly Manufacturing Inc., Lorraine, KS: scale readability ± 0.45 kg) for 2 consecutive days (d 0 and 1) after the limit-feeding period to obtain an initial BW (Stock et al., 1983). On d 0, steers were implanted with Component TE-IS (Elanco Animal Health, Greenfield, IN) and were vaccinated with Haemophilus somnus (Somubac; Pfizer Animal Health). Steers were stratified by BW within respective BW block. Steers were housed in uncovered, soil-floor pens (7.3 × 54.9 m). Steers were reimplanted with Component TE-S (Elanco Animal Health) 72 d after initial implant. Six dietary treatments (6 replications per treatment) were assigned randomly to pens within BW block. Steers were individually weighed once at the end of the experiment, and a 4% pencil shrink was applied for calculation of final live BW. Carcass adjusted per-

formance was calculated using HCW adjusted to a common DP of 63%. Feed bunks were assessed at approximately 0600 h and managed so that trace (≤0.2 kg) amounts of feed were left in the bunk each morning at time of feeding. Feed was delivered with a truck mounted mixer and delivery unit (Roto-Mix model 274, Roto-Mix, Dodge City, KS; scale readability ± 0.91 kg) each morning at 0800 h. Steers were adapted to finishing diets over a 21-d period with a series of 4 diets containing 39, 29, 19, and 9% alfalfa hay (DM basis) for 3, 4, 7, and 7 d, respectively, with corn grain replacing alfalfa hay. Concentration of wet distillers grains with solubles (20%; WDGS; Bridgeport Ethanol LLC, Bridgeport, NE), corn silage (15%), and liquid supplement (6%) were included at the same concentration in the adaptation diets as the finishing diets (DM basis; Table 1). Beet pulp (Western Sugar Cooperative, Scottsbluff, NE) was included in both the DRC- and SFC-based diets at 0, 10, or 20% (DM basis), respectively, replacing corn. The beet pulp (22.4% DM, 10.1% CP, 46.3% NDF) used in the current experiment was delivered as needed from November 2010 until February 2011 and was stockpiled in a concrete bunker silo through the remainder of the experiment. Urea was included in both DRC and SFC diets at 0.30 and 0.40% of diet DM, respectively, to meet or exceed degradable intake protein requirements (NRC, 1996). The liquid supplement was formulated to provide 33 mg/ kg monensin (Elanco Animal Health) and 8.7 mg/kg tylosin (Elanco Animal Health) in the diet. Ingredient and diet samples were collected weekly and dried in a 60°C forced-air oven for 48 h to determine DM of the samples (AOAC International, 1997; Method 930.15). Composited ingredient samples were sent to a commercial laboratory (Servi-Tech Laboratories, Hastings, NE) and analyzed for CP (AOAC International, 2000; Method 990.03), NDF (ANKOM, 2006), ether extract (AOAC International, 2006; Method 2003.6), Ca, P, S (Mills and Jones, 1996), and total starch (AOAC

320 International, 2000; Method 996.11) content. The SFC was processed at a local commercial feedlot (Panhandle Feeders, Morrill, NE; target flake density of 0.348–0.360 kg/L) and was shipped to the Panhandle Research Feedlot 3 times weekly. The commercial feedlot processed SFC using a Ferrell-Ross mill (Ferrell-Ross, Roll Manufacturing Inc., Hereford, TX) equipped with 45.7 × 91.4 cm corrugated rollers. Dry-rolled corn was processed at the research feedlot using a roller mill. A composite of DRC samples was analyzed for particle-size determination. United States Bureau of Standard sieves #1, 3, 6, 12, 30, and 70 (9,500, 6,300, 4,760, 3,360, 1,680, and 212 μ screen opening, respectively) were used for determination of the geometric mean diameter (μ) for each hybrid. The United States Bureau of Standard sieves were placed in a Fritsch Analysette wet sieving device (Model 8751, FritschGmbH, Idar-Oberstein, Germany) for particle-size analysis. The sieves were placed in the following order, from top to bottom, #1, #3, #4, #6,

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#12, #30, and #70. Approximately 30 g of sample (DM) was evenly distributed across the top screen, and the cap was secured onto the device. Samples were subjected to a 5-min period of vibration and spray, which moved particles down through the screens. Particles from each separate screen were cleaned onto preweighed filter papers that were dried for 24 h at 100°C. Filter papers and sample retained on each screen were weighed after being dried for 24 h at 100°C. Duplicate samples of corn underwent this procedure. The geometric mean diameter and the geometric SD of the samples were calculated using the method described by Behnke (1994). Additionally, the proportion of sample that was not retained on a screen was calculated to determine the proportion of samples smaller than 212 μ. The geometric mean diameter and the geometric SD of the DRC was 3,080 and 1.6 μ, respectively. Steers in the heavy BW block were harvested on d 154, and steers in the medium and light BW blocks were harvested on d 174 at a commercial

abattoir (Cargill, Fort Morgan, CO). All carcass data were collected by Diamond T Livestock Services (Yuma, CO). Hot carcass weight and liver score data were collected on the day of slaughter. Carcass 12th-rib fat, marbling score, and LM area were recorded following a 48-h carcass chill. Yield grade was calculated using carcass measurements and the formula of Boggs et al. (1998). Final BW, ADG, and G:F were calculated based on HCW adjusted to a common DP of 63. Hot carcass weights were used to reduce errors associated with gut-fill differences among dietary treatments (Meyer et al., 1960; Stock et al., 1983; Watson et al., 2013). Dietary NEm and NEg content was estimated from observed animal performance using equations from the NRC (1996) as described by Vasconcelos and Galyean (2008). Animal performance and carcass data were analyzed using the GLIMMIX procedure of SAS (SAS Institute Inc., Cary, NC) as a randomized block design with pen serving as the experimental unit. Factors included in the

Table 1. Experimental diets (DM basis) fed to steers in Exp. 1 DRC1 Item Ingredient, %  DRC  SFC   Beet pulp  WDGS3   Corn silage  Supplement4 Analyzed nutrient composition, %  CP  Fat  Ca  P  S

SFC2

0

10

20

0

10

20

59.0 — — 20.0 15.0 6.0

49.0 — 10.0 20.0 15.0 6.0

39.0 — 20.0 20.0 15.0 6.0

— 59.0 — 20.0 15.0 6.0

13.3 4.5 0.57 0.35 0.14

13.5 4.2 0.63 0.34 0.15

13.6 3.9 0.68 0.32 0.15

— 49.0 10.0 20.0 15.0 6.0   13.8 4.0 0.64 0.33 0.15

— 39.0 20.0 20.0 15.0 6.0   13.9 3.8 0.68 0.31 0.15

 

13.7 4.2 0.57 0.34 0.14

DRC = concentration dry-rolled corn–based diets with 0, 10, and 20% (DM) or beet pulp. SFC = concentration steam-flaked corn–based diets with 0, 10, and 20% (DM) or beet pulp. 3 WDGS = wet distillers grains with solubles (Bridgeport Ethanol LLC, Bridgeport, NE). 4 Supplements containing DRC included 0.3% urea and diets containing SFC included 0.4% urea. Supplement were also formulated to provide a dietary DM inclusion of 0.3% salt, 60 mg/kg Fe, 40 mg/kg Mg, 25 mg/kg Mn, 10 mg/kg Cu, 1 mg/kg I, 0.15 mg/kg Se, 1.5 IU/g vitamin A, 0.15 IU of vitamin D, 8.81 IU/kg vitamin E, 33 mg/kg monensin (Elanco Animal Health, Greenfield, IN), and 8.7 mg/kg tylosin (Elanco Animal Health). 1 2

Feeding sugar-beet pulp to finishing steers

Table 2. Dietary composition (%DM) and days on feed of control (CON), low–beet pulp (LOBP), and high–beet pulp (HIBP) adaptation methods (Exp. 2) Days fed 1–3 1

Adaptation CON  Alfalfa   Beet pulp  DRC3  WDGS4  Supplement5 LOBP  Alfalfa   Beet pulp  DRC  WDGS  Supplement HIBP  Alfalfa   Beet pulp  DRC  WDGS  Supplement

 

46 6 22 20 6   34 18 22 20 6   26 26 22 20 6

4–7 2  

36 6 32 20 6   27 15 32 20 6   21 21 32 20 6

8–14 3  

26 6 42 20 6   20 12 42 20 6   16 16 42 20 6

15–21 4  

16 6 52 20 6   13 9 52 20 6   11 11 52 20 6

22–1651 Finisher2  

6 6 62 20 6   6 6 62 20 6   6 6 62 20 6

Weighted average for days on feed for all 3 weight blocks (light, medium, and heavy). 2 Laboratory analyzed values for finishing diet: 13.4% CP, 4.6% ether extract, 1.04% Ca, 0.26% P, 0.75% K, 0.19% S. 3 DRC = dry-rolled corn. 4 WDGS = wet distillers grains with solubles. 5 Supplement formulated to provide a dietary DM inclusion of 0.3% salt, 60 mg/kg Fe, 40 mg/kg Mg, 25 mg/kg Mn, 10 mg/kg Cu, 1 mg/kg I, 0.15 mg/kg Se, 1.5 IU/g vitamin A, 0.15 IU of vitamin D, 8.81 IU/kg vitamin E, 33 mg/kg monensin (Elanco Animal Health, Greenfield, IN), and 8.7 mg/kg tylosin (Elanco Animal Health). 1

model were corn processing, beet-pulp concentration, corn processing × beetpulp concentration, with BW block as a random variable. If the corn processing × beet-pulp concentration interaction was not significant (P > 0.05), main effects were discussed. Orthogonal contrasts were used to detect linear and quadratic effects of beet-pulp level across both corn processing types when no significant interaction existed and within corn processing when a significant interaction was present.

Exp. 2 Grain Adaptation In Exp. 2, yearling British × Continental steers (n = 232; BW =

326 ± 15 kg) were separated into 3 weight blocks, stratified by BW, and assigned randomly within strata to 18 feedlot pens (n = 6 replications per treatment), with 12 or 13 steers per pen 2 wk after receiving using the same procedures as described in Exp. 1. Pen served as the experimental unit. Treatments were imposed during grain adaption (21 d) using 3 grain adaptation programs (Table 2). Within each program, 4 grain adaption diets were fed for 3, 4, 7, and 7 d. Both beet-pulp programs increased DRC inclusion while alfalfa and wet beet pulp decreased, whereas DRC replaced alfalfa in the control treatment. In the control treatment, ground-alfalfa-hay inclusion decreased

321 from 46 to 6% and beet pulp was held constant at 6% in all step diets. Beet-pulp adaption programs included a low–beet pulp treatment (LOBP) in which beet pulp decreased from 18 to 6% and alfalfa hay from 34 to 6%, or a high–beet pulp treatment (HIBP) in which both beet pulp and alfalfa hay were decreased from 26 to 6%. After grain adaption, all steers were fed a common finishing diet for the remainder of the feeding period. All step diets and the finishing diet contained 20% corn-based WDGS and 6.0% liquid supplement that was formulated to provide 0.25% urea, 33 mg/kg monensin (Elanco Animal Health), and 8.7 mg/kg tylosin (Elanco Animal Health) in the diet. Experiment 2 was conducted concurrently with Exp. 1 and used the same source of beet pulp and WDGS. All steers were offered ad libitum access to feed and water during the experiment. Before experiment initiation, steers were limit fed a 50% ground alfalfa hay and 50% WDGS (DM basis) diet for 5 d at 1.8% of BW to minimize variation in gut fill. Upon initiation of the experiment, steers received the same vaccinations as described in Exp. 1. Steer weighing, feeding, and sample collection procedures were the same as Exp. 1. On d 28, following grain adaptation, and after being fed a common finishing diet for 7 d, BW were collected, and steers were implanted with Component TE-S (Elanco Animal Health). A 4% pencil shrink was subtracted from this BW to obtain 28-d BW. After 148 or 181 d on feed, steers were weighed and transported to a commercial abattoir (Cargill, Fort Morgan, CO). Final weighing, carcass collection, and calculation of BW, ADG, and G:F used the same procedures as Exp. 1. Animal performance data and carcass characteristics were analyzed using the GILIMMIX procedure of SAS (SAS Institute Inc.) as a randomized block design. Pen was the experimental unit, fixed effect was treatment, and block was treated as a random effect. Treatment comparisons were

322 made using pair-wise comparisons when the F-test statistic was significant.

RESULTS AND DISCUSSION Exp. 1 Feedlot Performance Data. There was a tendency (P = 0.07) for an interaction between corn processing method and beet-pulp concentration for DMI (Table 3). The corn-processing-method × beet-pulpconcentration interaction was not significant for all other performance or carcass variables. Final BW and carcass adjusted BW decreased linearly (P < 0.01) as beet-pulp concentration increased in the diet. Dry-matter intake decreased linearly (P < 0.01) as beet-pulp concentration increased in both DRC- and SFC-based diets. Gain decreased linearly (P < 0.01) with increasing concentration of beet pulp in both DRC and SFC finishing diets. However, G:F was not different (P = 0.49) among beet-pulp concentrations in the finishing diet. The lack of difference in G:F is likely due to the change in magnitude when comparing 0 and 20% beet pulp within each corn processing method. Drymatter intake decreased 9.3 and 4.9% (for DRC and SFC, respectively), and this change was similar to the decrease noted for ADG (8.3 and 4.2%, DRC and SFC, respectively). Dietary NEg increased linearly (P = 0.05) as beet-pulp concentration increased. Dietary NEm tended (P = 0.06) to increase linearly with increasing beetpulp concentration. These estimates for dietary NEm and NEg suggest energy content of the diet increases with beet-pulp concentration. However, as described earlier the concomitant reduction in DMI and ADG results in G:F to numerically improve with increasing concentration of beet pulp. A linear decrease in final BW was observed as beet-pulp concentration increased in the current experiment. Similar linear decreases in final BW have been reported in other research (Bauer et al., 2007). The authors reported a 22-kg reduction in final

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BW when wet beet-pulp concentration in the diet increased from 5 to 20% (Bauer et al., 2007). Dry-matter intake decreased linearly in response to increasing beet-pulp concentration in both DRC- and SFC-based diets. In support of the current experiment, Bauer et al. (2007) also observed a linear decrease in DMI as beet pulp replaced HMC. Similarly, Weichenthal et al. (1993) reported a 6 and 11.7% reduction in DMI for steers fed 10 or 20% (respectively) beet pulp compared with the control. Likewise, Park et al. (2001) measured a reduction in DMI for steers fed 8.5% (10.6 kg/d) or 12.5% (10.7 kg/d) wet beet pulp compared with those fed a corn-based control diet (11.9 kg/d). Bauer et al. (2007) attributed the decrease in DMI to increased ruminal fill that resulted from an increase in the bulkiness of the diet as beet pulp replaced corn. It has not been determined whether the decrease in DMI commonly measured when beet pulp is included in the diet is due to an increase in fiber content or some other factor associated with beet pulp. Similar to final BW and DMI, ADG decreased linearly as beet-pulp inclusion increased in the diet. Other authors have reported these reductions in ADG when beet pulp is included in the finishing diet (Weichenthal et al., 1993; Bauer et al., 2007). Bauer et al. (2007) observed a 13.2% reduction in ADG for steers fed 20% beet pulp compared with that of steers fed 5%. Similarly, Weichenthal et al. (1993) reported an 11% reduction for ADG for steers fed 20% beet pulp compared with those fed a corn-based control diet. The reduction in ADG reported in the current experiment and in other research may be due to the reduction in DMI commonly expressed by cattle fed increasing concentrations of beet pulp. Gain efficiency was not influenced by the addition of beet pulp to the finishing diet. Weichenthal et al. (1993) and Park et al. (2001) reported no differences in G:F when comparing the G:F of steers fed beet pulp to that of steers fed a control diet containing no beet pulp. Similar to the current experiment,

concomitant decreases in both DMI and ADG for all beet-pulp concentrations were most likely responsible for the lack of difference in G:F reported by Weichenthal et al. (1993) and Park et al. (2001). However, Bauer et al. (2007) reported a linear decrease in G:F as beet-pulp concentration increased in the diet. Steers fed 12.5 and 20% beet pulp had 4.2 and 8.4% poorer G:F compared with steers fed only 5% beet pulp (Bauer et al., 2007). Steers fed DRC-based diets had greater DMI (P = 0.03) compared with steers fed diets containing SFC. Also, G:F was improved (P < 0.01) for steers consuming diets containing SFC compared with diets with DRC as the grain source. In a review examining the effect of corn processing on finishing performance, Owens et al. (1997) reported that DMI was statistically lower for cattle fed SFCbased (8.35 kg/d) diets compared with cattle fed DRC (9.45 kg/d) diets. Other research (Barajas and Zinn, 1998; Ward et al., 2000; Corona et al., 2005) has reported similar reductions in DMI for cattle fed SFC- compared with those fed DRC-based diets. The reduction in DMI observed in the current experiment is in agreement with the DMI results reported in the feeding experiments previously mentioned (Barajas and Zinn, 1998; Ward et al., 2000; Corona et al., 2005). The observation of an improvement in G:F resulting from steam flaking was numerically less compared with the average reported by Owens et al. (1997) but similar to the results reported in other finishing studies (Barajas and Zinn, 1998; Brown et al., 2000; Ward et al., 2000). One explanation for a smaller improvement in G:F when comparing the current experiment with the meta-analysis conducted by Owens et al. (1997) may have been due to the 20% WDGS that was added to the basal diets. Some authors have reported that WDGS improves G:F for steers fed DRC-based diets (Vander Pol et al., 2008; Corrigan et al., 2009); however, G:F is not improved by including WDGS in SFC diets (Corrigan et al., 2009; Luebbe

6 72   313 593 589 10.3 1.66 1.65 0.163 0.160 2.86 1.27 1.91   371 591 1.45 80.4 3.43   11.1 4.2 84.7

2.83 1.25 1.89   376 572 1.55 79.1 3.60   7.0 2.8 90.0

10

6 72   314 603 597 10.7 1.72 1.69 0.162 0.159

0

2.89 1.29 1.94   360 578 1.40 79.1 3.33   7.0 4.2 87.3

6 72   314 580 572 9.7 1.59 1.55 0.164 0.159

20 6 72   315 605 594 10.3 1.73 1.67 0.169 0.163   2.88 1.29 1.93   374 586 1.52 80.4 3.55   9.9 4.2 85.9

0 6 72   315 600 593 10.0 1.7 1.67 0.171 0.166   2.93 1.32 1.97   374 570 1.50 81.0 3.47   10.29 2.94 86.76

10

SFC

6 72   313 587 581 9.8 1.63 1.60 0.168 0.164   2.92 1.31 1.96   366 563 1.42 79.1 3.42   11.3 1.4 87.3

20 – –   2.2 5 6.9 0.14 0.03 0.04 0.003 0.002   0.03 0.02 0.02   4 12 0.05 1.1 0.10        

SEM2 – –   0.83 0.77 0.46 0.07 0.79 0.35 0.46 0.86   0.65 0.65 0.69   0.47 0.13 0.63 0.82 0.61     0.72  

C×L – –   0.74 0.12 0.42 0.03 0.14 0.42 <0.01 <0.01   <0.01 <0.01 <0.01   0.44 0.34 0.44 0.36 0.68     0.81  

Corn type – –   0.89 <0.01 <0.01 <0.01 <0.01 <0.01 0.89 0.49   0.08 0.09 0.69   <0.01 0.52 <0.01 0.20 0.02     0.85  

Level

P-value3

– –   0.63 <0.01 <0.01 <0.01 <0.01 <0.01 0.97 0.79   0.06 0.06 0.05   <0.01 0.36 <0.01 0.45 <0.01        

L

– –   0.97 0.42 0.26 0.67 0.44 0.19 0.70 0.29   0.49 0.48 0.45   0.24 0.49 0.90 0.11 0.66        

Q

Beet level

2

1

DRC = dry-rolled corn, SFC = steam-flaked corn, beet-pulp concentration at 0, 10, and 20% of diet DM. SEM = standard error of the mean for the interaction. 3 C × L = P-value for the beet-pulp-concentration × corn-processing-method interaction, Corn type = P-value for the main effect of corn processing method, Level = P-value for the main effect of beet-pulp concentration, L = P-value for the linear effect of beet-pulp concentration, Q = P-value for the quadratic effect of beet-pulp concentration. 4 Calculated from HCW, adjusted to a common DP of 63. 5 Dietary energy values calculated from performance data using energy requirement equations for maintenance and shrunk BW gain as described by Vasconcelos and Galyean (2008). 6 Marbling score: 500 = Small 0; 600 = Modest 0. 7 Calculated YG = 2.50 + 6.35 × fat thickness (cm) + 0.0017 × HCW (kg) − 2.06 × LM area (cm2) + 0.2 × KPH (%); Boggs et al. (1998). 8 Liver score = % of cattle, averaged across treatment.

Pens, no. Steers, no. Animal performance   Initial BW, kg   Final BW, kg   Adjusted final BW,4 kg   DMI, kg/d   ADG, kg   Adjusted ADG,4 kg  G:F   Adjusted G:F4 Dietary energy5   ME, Mcal/kg  NEm, Mcal/kg  NEg, Mcal/kg Carcass characteristics   HCW, kg  Marbling6   12th-rib fat, cm   LM area, cm2  YG7 Liver score8  A  A+  0

Item

DRC

Dietary treatment1

Table 3. Effect of corn processing method and sugar beet–pulp concentration on finishing performance, dietary energy content, and carcass characteristics (Exp. 1)

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324

Nichols et al.

Table 4. Feedlot performance and carcass characteristics of cattle adapted to grain using control (CON), low–beet pulp (LOBP), or high– beet pulp (HIBP) adaptation methods (Exp. 2) Item Performance   Initial BW, kg   Final BW, kg   Adjusted final BW,1 kg   DMI, kg/d   28 d   Final   ADG, kg   28 d   Final    Adjusted final1  G:F   28 d   Final    Adjusted final1 Carcass characteristics   HCW, kg  DP   LM area, cm2   12th-rib fat, cm  YG2  Marbling3   Liver abscess, %

CON

LOBP

HIBP

SEM

P-value

  326 597 596   9.9 10.8   1.90 1.66 1.65   0.192 0.154 0.152   376 62.8 79.6 1.50 3.67 629 19.5

  326 612 610   9.7 11.0   1.86 1.74 1.73   0.192 0.159 0.157   384 62.7 79.6 1.52 3.75 635 16.9

  326 609 610   9.5 10.9   1.92 1.73 1.73   0.202 0.159 0.159   385 63.0 79.8 1.50 3.72 636 12.9

  0.4 12.7 9.9   0.15 0.18   0.09 0.12 0.08   0.007 0.003 0.003   6.2 0.4 1.29 0.05 0.08 18.5 -

  0.30 0.19 0.32   0.07 0.58   0.80 0.21 0.07   0.20 0.26 0.11   0.32 0.78 0.99 0.80 0.61 0.90 0.63

Final BW was calculated from HCW using a common DP of 63%. Calculated YG = 2.50 + 6.35 × fat thickness (cm) + 0.0017 × HCW (kg) − 2.06 × LM area (cm2) + 0.2 × KPH (%); Boggs et al. (1998). 3 Scores: 600 = Modest 0, 700 = Moderate 0. 1 2

et al., 2012; Meyer et al., 2013). As expected, diets containing SFC had greater dietary NEm and NEg than DRC diets (P < 0.01). Carcass Data. There was no cornprocessing × beet-pulp interaction (P ≥ 0.13) for carcass data (Table 3). Hot carcass weight, calculated YG, and 12th-rib fat depth decreased linearly (P ≤ 0.02) with increasing beet-pulp concentration. Marbling score, LM area, and incidence of liver abscesses were not different (P ≥ 0.13) among treatments. Similar to the current experiment, Bauer et al. (2007) observed a linear decrease in HCW as beet pulp replaced HMC in the finishing diet. However, beet pulp did not affect other carcass characteristics of interest (12th-rib fat, KPH, LM area, YG, or marbling score; Bauer et al., 2007). Likewise, Park et al. (2001) reported a similar reduction

in HCW with increasing concentration of beet pulp in the diet. In contrast to Bauer et al. (2007), Park et al. (2001) reported a significant reduction in 12th-rib fat thickness for steers fed 8.5 and 12.5% (DM basis) beet pulp compared with none.

Exp. 2 Feedlot Performance Data. Steers adapted to grain using HIBP tended (P = 0.07) to consume less DM during the 21-d adaption period compared with steers fed CON, with LOBP being intermediate (Table 4). Dry-matter intake was not different (P = 0.58) among diets during the finishing period. Average daily gain and G:F were not different (P = 0.09 and P = 0.20, respectively) among treatments during the grain adaptation period. However, based

on carcass-adjusted final BW, steers adapted using HIBP and LOBP tended (P = 0.07) to have greater ADG compared with steers adapted with the control treatment. Gain efficiency during the entire feeding period was not different (P = 0.11) among treatments but was numerically greater for steers adapted using either beet-pulp adaptation method compared with steers adapted with the CON diet. In the current experiment, steers adapted to the finishing diet using beet pulp tended to have lower DMI for the initial 28 d compared with steers adapted to the final diet using a traditional adaptation. MacDonald and Luebbe (2012) observed no differences in DMI when using diets containing Sweet Bran (Cargill Corn Milling, Blair, NE) or combinations of Sweet Bran and cottonseed hulls compared with those adapted with a diet containing alfalfa hay. In agreement with MacDonald and Luebbe (2012), Huls et al. (2009) did not observe a difference in DMI when comparing steers adapted to a common diet by decreasing Sweet Bran compared with steers adapted by decreasing alfalfa hay. However, research similar to the one reported by Huls et al. (2009) noted a significant reduction in DMI for steers adapted to the finishing diet using a combination of modified distillers grains with solubles and wet corn gluten feed (Golden Synergy, ADM, Columbus, NE) compared with that of steers adapted to the finishing diet using alfalfa hay (Dib et al., 2012). Likewise, Birkelo and Lounsbery (1993) reported a 22% reduction in DMI for steers adapted to a finishing diet using WDGS compared with steers fed diets with DRC replacing alfalfa hay and brome hay. Similar to the present experiment, Schneider et al. (2012) observed a tendency (P < 0.09) for reduced DMI during the adaptation period when RAMP (Cargill Corn Milling, Blair, NE) replaced alfalfa hay. From these data we can conclude that different adaptation strategies induce different responses in DMI. It is unclear why some nontraditional adaptation diets decrease DMI relative to control-fed steers. These

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differences in DMI may be related to energetic differences of the by-product as well as concentrations fed and feeds replaced. In all these studies, the differences are expressed relative to a control. Variation may exist across studies for adaptation due to length of adaptation, location, weather, bunk management, or any combination. Therefore, relative differences from using a by-product instead of a forage source may also be influenced by performance of the control diet. During the grain adaptation period, ADG was not different among treatments. Over the entire finishing period, steers adapted using HIBP and LOBP tended to have greater ADG compared with steers adapted with CON. Increases in ADG may have occurred during the grain adaption period and were not realized until the end of the feeding period when carcass-adjusted values were available. This difference may be due to the difficulty often associated with accurately measuring change in BW over short durations of time because of variation in gut fill. However, it is not clear whether or not the increase in gain occurred during adaptation. Other grain adaptation research has reported no differences in ADG during the adaptation period (Birkelo and Lounsbery, 1993; Dib et al., 2012; MacDonald and Luebbe, 2012). However, Huls et al. (2009) observed a 4.8% improvement in ADG steers fed Sweet Bran compared with the control. The improvement in ADG observed by Huls et al. (2009) is likely due to the greater energy content of Sweet Bran compared with alfalfa hay. Similarly, Buttrey et al. (2012) observed improved ADG during the adaption period when RAMP was compared with a traditional alfalfabased adaption and tended to increase ADG over the entire feeding period. Gain efficiency was similar among treatments during the grain adaptation period and tended (P = 0.11) to be greater overall for steers adapted using beet pulp. MacDonald and Luebbe (2012) observed no difference in G:F when comparing steers adapted with cottonseed hulls and Sweet Bran

to the control diet. However, steers adapted to the finishing diet using Sweet Bran (HSB) had 9.8% higher G:F during the adaptation period, but G:F was not different over the entire finishing period. Huls et al. (2009) reported a 4.4% improvement in final G:F for steers adapted to the finishing diet with Sweet Bran compared with steers adapted with alfalfa hay. Likewise, Birkelo and Lounsbery (1993) and Dib et al. (2012) observed a 22.7 and 7.4% improvement, respectively, in G:F for steers adapted with WDGS or Golden Synergy compared with steers adapted with traditional alfalfa hay adaptation diets. Schneider et al. (2012) also reported an overall improvement in G:F when adapting steers with RAMP compared with a traditional adaptation diet. Carcass Data. There were no differences (P ≥ 0.32) among treatments for carcass characteristics (Table 4). Both Huls et al. (2009) and MacDonald and Luebbe (2012) observed a 2.2% increase in HCW for steers adapted to finishing diets using Sweet Bran rather than alfalfa hay. Schneider et al. (2012) reported a tendency for improved HCW when adapting steers with RAMP, and Buttrey et al. (2012) reported increased HCW and 12th-rib fat thickness when adapting steers with RAMP compared with alfalfa hay. However, Dib et al. (2012) reported a 0.5-unit decrease in DP that resulted from using a combination of modified distillers grains with solubles and wet corn gluten feed to adapt cattle to a finishing diet.

IMPLICATIONS The inclusion of beet pulp in the finishing diet decreases DMI in both DRC and SFC diets. Because there was a concomitant decrease in ADG, G:F was not different across treatments. Adapting cattle to finishing diets using beet pulp compared with alfalfa hay tended to increase ADG and decrease DMI during the grain adaptation period. Replacing up to 50% of the forage in an adaptation diet with beet pulp is an effective method for transitioning cattle to fin-

ishing diets and reducing the amount of roughage needed. Markets will dictate whether replacing alfalfa hay or a portion of corn grain with beet pulp will be economical in finishing diets.

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