Effects of Level of Dried Distillers Grain Supplementation on Native ...

The Professional Animal Scientist 25 (2009):596–604

©2009 American Registry of Professional Animal Scientists

Effects of Level of Dried Distillers Grain Supplementation on

Native Pasture and Subsequent Effects on Wheat Pasture Gains K. H. Jenkins,* J. C. MacDonald,*†1 PAS, F. T. McCollum III,‡ PAS, and S. H. Amosson‡ *Texas AgriLife Research, Amarillo 79106; †West Texas A&M University, Canyon 79016; and ‡Texas AgriLife Extension Service, Amarillo 79106

ABSTRACT Crossbred steers (225 ± 16.8 kg) were stratified by BW, blocked by grazing group, and randomly assigned to treatment to determine the effects of level of dried distillers grain (DDG) supplementation on native pasture ADG, subsequent wheat pasture ADG, supplement efficiency, and economic return to supplement. One hundred twenty steers grazed dormant rangeland for 56 d and were supplemented 3 times/wk with the equivalent of 7 d of corn DDG at 0, 0.25, 0.50, or 0.75% of BW per day (DM basis). Average daily gain increased linearly (P < 0.001) with level of DDG. After grazing rangeland, supplementation ceased and 60 steers (1 grazing block) were moved to wheat pasture for 76 d. During wheat grazing, nonsupplemented steers compensated and final BW was not different between the nonsupplemented and 0.25% of BW groups. However, final BW tended (P = 0.08) to increase with level of DDG after wheat grazing. Supplement efficiency while grazing range was 0.427, 0.369, and 0.338 kg added ADG/kg supplement DM, respectively, for the 0.25, 0.50, and 0.75% of 1 Corresponding author: jcmacdonald@ ag.tamu.edu

BW treatments. However, total system efficiency was reduced to 0.017, 0.218, and 0.171 kg added ADG/kg supplement DM, respectively, after grazing wheat pasture. Economic return was greatest for 0.75% of BW when steers were marketed after dormant range grazing. If marketing occurred after wheat grazing, returns were maximized by 0.50% of BW unless the delivered cost of DDG was low. If the delivered cost of DDG was $100/US ton, economic returns were maximized by 0.75% of BW supplementation after wheat grazing. Key words: dried distillers grains, native range, cattle, wheat pasture, supplement efficiency

INTRODUCTION More than 75% of the beef calves produced in the United States will be used as stocker calves to graze forages before entering feedlots for confinement finishing (Peel, 2000). The majority of these calves are born in the spring and weaned in the early fall. The Southern Plains region accounts for nearly 30% of feeder cattle that do not enter feedlots (i.e., stocker cattle; Peel, 2003). In the Texas Panhandle, rangelands are primarily shortgrass

prairie with the predominant grasses consisting of buffalograss, blue grama, sideoats grama, and western wheatgrass. These areas may be used by stocker cattle during the fall before grazing winter wheat. Because of the declining nutritional value of these pastures during the fall and winter, ADG is usually low (Krysl et al., 1989). Depending on the severity and duration of the restriction, cattle may or may not fully compensate during a subsequent grazing phase on a higher plane of nutrition (Drouillard et al., 1991; Jordan et al., 2000). Therefore, supplementation to improve performance on dormant pastures may be beneficial, even though the cattle will subsequently be grazing high-quality pastures. Dried distillers grains (DDG) are high in protein and energy and have improved the performance of cattle grazing rangeland and introduced pastures (MacDonald and Klopfenstein, 2004; Morris et al., 2005; Gustad et al., 2006). In addition, DDG may be a less expensive source of energy and protein compared with corn or other protein sources. However, although supplementation of stocker cattle may be economically beneficial in one segment of a production system, the

Dried distillers grains effects on range and wheat pasture gain

overall benefit may be reduced by compensatory gain in a subsequent segment of the system (Jordan et al., 2000). Efficiency of ADG, coupled with changing prices of cattle and supplemental feed, makes economic analysis an important exercise when determining supplementation strategies. Therefore, our objectives were to determine the effects of level of DDG supplementation on dormant rangeland and carryover effects during wheat pasture grazing and the economic feasibility of supplementation throughout the production system.

MATERIALS AND METHODS All experimental procedures were approved by the Amarillo Area Cooperative Research, Education, and Extension Team Animal Care and Use Committee. Crossbred steers (225 ± 16.8 kg) were used to determine the effects of supplemental DDG on steer performance on dormant rangeland and the subsequent effects on performance when steers grazed winter wheat pasture. One hundred twenty steers were stratified by BW and assigned randomly to 1 of 24 supplementation groups in 2 grazing blocks. A supplementation group consisted of 5 steers, which served as the experimental unit for the study. The steers had been preconditioned for 40 d, vaccinated against viral (Vista 5, Intervet, Millsboro DE) and clostridial diseases (Vision 7, Intervet), and treated for internal parasites (Ivomec, Merial, Duluth, GA). Immediately before initiating the trial, the steers were limit-fed a TMR of 25% wet corn gluten feed, 25% steam-flaked corn, 30% alfalfa hay, 8% canola meal, 3% molasses, and 9% mineral supplement at 1.5% of BW (DM basis) for 7 d and were then weighed for 3 consecutive days to minimize rumen fill variation. The steers grazed dormant rangeland for 56 d from October 12 through December 7. Steers in each grazing block were rotated weekly through a set of 3 pastures to minimize pasture effects. The 3 pastures were approximately 34.4, 38.4, and 42.5 ha, and the pre-

dominant forage species were buffalograss [Bouteloua dactyloides (Nutt.) J. T. Columbus], blue grama [Bouteloua gracilis (Willd. ex Kunth) Lag. ex Griffiths], sideoats grama [Bouteloua curtipendula (Michx.) Torr.], and western wheatgrass [Pascopyrum smithii (Rydb.) A. Löve]. Within each block, treatments were supplemented with DDG at 0, 0.25, 0.50, or 0.75% of BW/d on a DM basis. There were 4 treatments, 12 experimental units per block, and 2 blocks, resulting in a total of 6 observations per treatment during the dormant range grazing phase. The amount of supplement was based on initial BW of the steers and was not adjusted during the 56-d supplementation period. The weekly amount of supplement was prorated and fed 3 times per week. Block 1 was supplemented on Monday, Wednesday, and Friday, and block 2 was supplemented on Tuesday, Thursday, and Saturday. Three times weekly, supplementation was used to compensate for limitations in the number of sorting pens at the facility, to allow both grazing blocks to be supplemented in the morning hours within a 6-d work week, and to mimic a supplementation system commonly used by producers in the Southern Plains region. At 0800 h on the designated day, a block was gathered into the handling facility and sorted into experimental units to receive supplement. The groups were then fed the assigned level of DDG and allowed 2 h to consume supplement before returning to graze. Any remaining supplement was collected and weighed back. Steers receiving no supplement were retained in the facility while other groups consumed supplement. On November 3, diet samples were collected using 2 ruminally fistulated steers that had previously been grazing native range. After evacuating the rumens, the steers grazed for approximately 20 min. Diet samples were collected, frozen, and later lyophilized and ground through a 1-mm screen in a Wiley mill (Thomas Scientific, Swedesboro, NJ). Samples of DDG were taken with each delivery and composited. The diet samples and

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DDG composite were sent to a commercial laboratory (Servi-Tech, Amarillo, TX) for nutrient analysis. Digestibility of the dormant range diet samples was determined by IVDMD (Tilley and Terry, 1963), modified by the addition of 1 g/L urea to the buffer (Weiss, 1994). Five forage standards with known in vivo digestibility values were included as standards in the in vitro analysis. Regression analysis was used to adjust IVDMD of the diet samples to an in vivo digestibility (Geisert, et al, 2007). After the 56-d rangeland-grazing period, the steers were held off feed and water for 24 h and weighed. One grazing block (60 steers) was then implanted with Revalor G (40 mg trenbolone acetate, 8 mg estradiol; Intervet) and moved to wheat pasture for 76 d. Twelve wheat pastures (2.2 ha each) were grazed by 5 steers each. Because of a lack of wheat pasture availability, block 2 did not graze wheat and was not included in the wheat-grazing analysis, which resulted in 3 observations per treatment for the wheat-grazing phase. While grazing wheat pasture, the steers had access to a mineral supplement containing 1.76 g monensin/kg (Rumensin, Elanco Animal Health, Indianapolis, IN). The steers consumed an average of 91 g/d. No other supplements were offered. At the end of wheat pasture grazing, the steers were held off feed and water for 24 h and weighed. Supplementation efficiency and incremental supplementation efficiency were calculated after rangeland grazing and again after wheat pasture grazing. Supplementation efficiency is the kilograms of BW added by supplementation per kilogram of supplement consumed, expressed relative to the nonsupplemented controls. Incremental supplementation efficiency calculates the efficiency of each increase in level of supplementation. Data were analyzed using the MIXED procedure (SAS Institute Inc., Cary, NC), with block as a random effect. The experimental unit was supplementation group, which consisted of 5 steers. Blocks included 2 grazing groups that were

598 supplemented on either Monday, Wednesday, and Friday, or Tuesday, Thursday, and Saturday. There were 6 observations per treatment during the dormant range grazing phase and 3 observations per treatment during the subsequent wheat pasture grazing phase. Orthogonal polynomial contrasts were developed to determine linear and quadratic responses to rates of supplementation. An economic analysis was conducted to evaluate the potential benefits of DDG supplementation during the rangeland grazing and the impact on returns to supplement if steers were retained through wheat pasture grazing. The cost of gain and the net return attributable to supplementation were calculated for each level of DDG supplement after grazing range and after grazing wheat. The cost of the additional ADG above that of the control group for each level of supplementation was calculated as follows:

Jenkins et al.

This analysis focused on the value of additional BW gain relative to the nonsupplemented controls. Any price slide because of added weight is implied when selecting the appropriate value of added BW. Additionally, costs over purchase price, such as those associated with delivery of the DDG to steers, are implied in the DDG cost. Sensitivity tables were developed by calculating net income attributable to supplementation over a range of DDG costs and values of added BW to demonstrate how an optimal supplementation strategy might change in different market conditions. The range of DDG costs and values of added BW attributable to supplement were selected to be evenly spaced and were intended to encompass a wide range of scenarios that producers might experience, but were arbitrary beyond those criteria.

Table 1. Nutrient analysis of diet samples and dried distillers grain (DDG) supplement Nutrient, % of DM CP ADF NDF Calculated TDN1 IVDMD In vivo digestibility2 Crude fat Ca P S

Diet sample 8.8 45.8 67.4 51.6 47.9 48.9 — — — —

DDG 31.6 — 32.8 — — 11.0 0.03 0.67 0.60

TDN calculated from ADF (88.90 − %ADF × 0.82).

1

In vivo digestibility regressed against IVDMD values of known standards: y = 0.473x + 0.2761.

2

RESULTS AND DISCUSSION

Cost of additional ADG = [1/ Rangeland Grazing supplement efficiency (see tables for Nutrient analysis of the dormant analysis after grazing dormant range rangeland and DDG is shown in Table and wheat, respectively)/908 × DDG 1. Crude protein, % ADF, % NDF, costs × 0.454]. [1] and digestibility were similar to that of other native range sampled in the The additional BW attributable to fall (Gunter et al., 1995; Hollingssupplementation was calculated as worth-Jenkins et al., 1996; Morris et follows: al., 2005). Initial BW of the treatment groups were not different (P > 0.31; Additional BW = [total BW gain of Table 2). Average daily gain increased supplemented group − total BW gain linearly (P < 0.001; Table 2) as level of nonsupplemented group of DDG increased. We expected a (see tables)]/0.454. [2] curvilinear response of ADG to level of DDG supplementation, which Net income attributable to supplewould indicate that the incremental mentation was then calculated as BW change decreased as the level of follows: supplementation increased, yet the quadratic contrast for ADG was not [Additional BW (equation [2]) × the significant (P = 0.16). Gustad et al. value of added BW] − [additional BW (2006) reported a significant curvi(equation [2]) × cost of additional linear response to ADG for cattle ADG (equation [1])]. grazing cornstalk residue and supplemented with DDG at 0.29 to 1.27% of The cost of additional ADG and the BW. The supplemented steers in the value of added BW were expressed study by Gustad et al. (2006) gained as dollars per pound and DDG was from 0.41 kg/d on the lowest level of expressed as dollars per US ton so supplementation to 0.82 kg/d on the that monetary values were consistent highest level. Although steers in the with US beef production standards. current study gained more rapidly at

similar levels of supplementation than those used by Gustad et al. (2006), the incremental improvement in ADG with supplemental DDG was similar. Griffin et al. (2009) summarized 14 studies in which DDG had been supplemented on medium- to highquality forage-based diets and reported a quadratic response of ADG to DDG supplementation. A quadratic response may have been less obvious in the current study because the supplementation rate was not as high. Nevertheless, the improved animal performance with supplemental DDG in the current study appears to agree with the observations of Gustad et al. (2006) for steers grazing diets of similar digestibility. Simulating native range, Morris et al. (2005) fed lowquality (53% TDN) bromegrass hay to heifers and supplemented DDG up to 0.95% of BW. Those cattle responded linearly, with ADG similar to those of the current study. Previous studies investigating the use of DDG as a supplement to forage have used daily supplementation frequency (Morris et al., 2005; Gustad et al., 2006; Griffin et al., 2009), whereas the current study provided

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Table 2. Initial BW, amount of supplement, ADG, and total BW gain of steers grazing dormant native pasture supplemented with increasing levels of dried distillers grains (DDG) Treatment1 Item Initial BW, kg Supplement, kg/d ADG,ab kg Total BW gain,ab kg Final BW,ac kg Supplement efficiency2 Incremental supplement efficiency3 a

Linear contrast (P < 0.001).

b

Quadratic contrast (P = 0.16).

c

0.00

0.25

0.50

0.75

SE

204 — 0.266 14.9 219 — —

205 0.511 0.484 27.1 232 0.427 —

205 1.023 0.643 36.0 241 0.369 0.311

205 1.534 0.784 43.9 249 0.338 0.276

1 — 0.038 2.1 2 — —

Quadratic contrast (P = 0.06).

Treatments included level of daily DDG supplementation (0.00, 0.25, 0.50, or 0.75% of BW) prorated and fed 3 times/wk during a 56-d dormant range grazing period.

1

2

Supplemental efficiency = (supplemented ADG − 0% of BW supplemented ADG)/amount of supplement consumed.

Incremental supplement efficiency = (ADG attributable to supplementation at level A − ADG attributable to supplementation at level B)/(kg of supplement consumed at level A − kg of supplement consumed at level B), where level A is the supplementation rate in a column and level B is the nearest supplementation rate in the column left of level A.

3

supplement 3 times weekly. Infrequent supplementation is known to reduce ADG and forage DMI (Loy et al., 2008; Stalker et al., 2009) and to reduce diet digestibility (Loy et al., 2007; Stalker et al., 2009). Loy et al. (2008) fed DDG at 0.21 or 0.81% BW either daily or 3 times weekly and found no interaction between frequency of supplementation and level of supplementation. Providing DDG 3 times weekly reduced ADG compared with providing DDG daily across both levels of supplementation. However, the additional ADG resulting from increasing the level of DDG supplement from 0.21 to 0.81% BW was remarkably similar for both supplementation frequencies (0.40 vs. 0.43 kg/d of additional ADG for daily and 3 times weekly, respectively). Therefore, although it is possible that the current data set underestimates the ADG response to DDG supplementation relative to the nonsupplemented control compared with previously reported studies (Morris et al., 2005; Gustad et al., 2006; Griffin et al., 2009), the incremental response to level of DDG supplement should be comparable across studies. It appears from these

studies that the improvement in ADG resulting from DDG supplementation for low- to medium-quality forages is consistent across forage types. In Table 2, supplement efficiency is expressed relative to the nonsupplemented group and relative to each incremental level of supplementation. During 56 d of dormant rangeland grazing, the steers receiving 0.75% of BW of DDG gained 0.518 kg/d more than the nonsupplemented steers. Forty-two percent (0.218 kg/d) of this difference was added by the first level of supplementation (0.25% of BW), suggesting a response to supplemental protein. Efficiency decreased as level of supplement increased, reflecting the diminished ADG response with each increment of supplemental DDG. In a study using dormant tallgrass prairie, Bodine and Purvis (2003) compared degradable intake protein to TDN ratios of supplements containing dry rolled corn (DRC) and soybean meal (SBM), DRC and soyhulls, or SBM to a cottonseed hull control. These supplements were supplied at 1.3, 1.3, and 0.42% of BW, respectively. Supplement efficiencies were 0.29, 0.14, and 0.67, respectively,

compared with the cottonseed hull control. The higher efficiency for the SBM treatment over the energy supplements suggested a response to supplemental protein that was similar to the current study, assuming the supplement met a degradable intake protein deficiency in both scenarios.

Wheat Pasture Grazing Subsequent performance of the steers from block 1 on wheat pasture is presented in Table 3. One steer died during the wheat-grazing phase. The initial BW for the deceased steer was removed from the wheat-grazing analysis. Average daily gain and total BW gain during wheat grazing appeared to decline with increasing level of supplementation provided while the steers were grazing rangeland, although the linear contrast was not significant (P = 0.13). At the beginning of wheat grazing, the steers that had not been supplemented on range were 12 to 26 kg lighter than the supplemented groups. During the wheat-grazing phase, the nonsupplemented steers compensated by gaining 0.110 to 0.175 kg/d more than the

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Jenkins et al.

Table 3. Wheat pasture performance of block 1 previously supplemented with increasing levels of dried distillers grains (DDG) on dormant native pasture Treatment1 Item Initial BW, kg ADG,b kg Total BW gain,b kg Final BW,c kg Compensation of nonsupplemented control,2 % a

a


b

Linear contrast (P = 0.13).

0.00

0.25

0.50

0.75

SE

216 0.901 68.5 284 —

228 0.726 55.5 284 100

237 0.791 60.1 297 38

242 0.736 56.0 298 46

5 0.081 6.2 8 —


c


1

Percent compensation of nonsupplemented controls vs. supplemented groups = (BW difference at the beginning − BW difference at the end)/BW difference at the beginning.

2

supplemented groups and overcame 38 to 100% of the initial BW differences. At the end of wheat grazing, BW was not different for the nonsupplemented steers and those receiving 0.25% of BW of DDG on rangeland (P = 0.96). However, the steers from the 2 highest supplementation groups on rangeland still appeared to be heavier (13 kg) than those that had not been supplemented (P ≤ 0.18). This resulted in a tendency for a linear increase in final BW with increasing level of DDG supplementation at the end of the wheat-grazing period (P = 0.08; Table 3). Similarly, Jordan et al. (2000) found that cattle restricted for 156 d during the winter did not completely compensate during summer grazing compared with the unrestricted cattle. The ability of steers to compensate after a period of nutrient restriction is largely influenced by the length and severity of restriction relative to nonrestricted steers. It is likely that steers receiving no supplement on rangeland were able to completely compensate relative to steers receiving 0.25% of BW of DDG because the severity of nutrient restriction between these 2 treatments was small relative to the severity of the nonsupplemented cattle compared with steers receiving greater levels of supplementation. Additionally, the length of restriction

(56 d) may have been short enough to allow the nonsupplemented steers to fully compensate relative to steers receiving 0.25% of BW of DDG. Drouillard et al. (1991) noted compensation in cattle undergoing a short duration (77 d), mild protein restriction during a subsequent finishing period. The performance of the nonsupplemented cattle compared with cattle supplemented with 0.25% of BW is consistent with a short duration, mild protein restriction. Although the observations of Drouillard et al. (1991) suggest that compensation of the nonsupplemented controls compared with the 0.25% of BW treatment should be expected with either a short or long duration of restriction, it is unclear whether 100% compensation for the nonsupplemented controls would have occurred had the length of grazing native range been greater.

Total System A summary of performance for the complete system is shown in Table 4. As discussed previously, supplementation with DDG on dormant rangeland increased steer ADG, which resulted in a linear increase in total BW gain while steers grazed dormant range (P < 0.001). However, by the end of wheat grazing, the BW differences

had narrowed because of compensatory gain by nonsupplemented steers. Hence, the supplement efficiency across the complete system was lower than the efficiency during the rangeland phase. In fact, after wheat grazing, the BW advantage for the 0.25% of BW treatment had disappeared and the calculated supplement efficiency approached zero. Klopfenstein et al. (2007) summarized 8 studies in which DDG were supplemented to cattle grazing smooth brome or native range during the growing season. In these studies, cattle were supplemented at 0.48 or 0.92% of BW and obtained supplemental efficiencies of 0.17 and 0.15 kg ADG/kg supplement, respectively. Greenquist et al. (2008) summarized 4 studies supplementing DDG (0.53% of BW) to cattle grazing smooth brome during the growing season. Those studies resulted in an average supplemental efficiency of 0.14 kg ADG/kg supplement. These efficiencies are similar to the efficiencies for the 0.50 and 0.75% of BW treatments of the current study after the cattle grazed the higher quality wheat pasture (0.218 and 0.171 kg ADG/kg supplement, respectively). Grazing high-quality forage at some point in the grazing system clearly reduces supplement efficiency. Nevertheless, total system

601


Table 4. Total system performance of cattle supplemented dried distillers grains (DDG) on range and subsequent wheat grazing Treatment1 Item

0.00

Total BW gain on range (56 d), kg Total BW gain on wheat2,b (76 d), kg Total system BW gain2,c (132 d), kg Total supplement,3 kg System supplement efficiency4 Incremental system supplement efficiency5 a

a


b


14.9 68.5 80.3 — — —

0.25

0.50

0.75

SE

27.1 55.5 80.8 28.6 0.017 —

36.0 60.1 92.8 57.3 0.218 0.418

43.9 56.0 95.0 85.9 0.171 0.077

2.1 6.2 8.2 — — —


c


1

2

Block 1 only.

3

Total kilograms supplement per head fed during dormant range grazing.

System supplemental efficiency = (supplemented total system BW gain − 0% of BW supplemented total system BW gain)/amount of supplement fed.

4

System incremental supplement efficiency = (total system BW gain attributable to supplementation at level A − total system BW gain attributable to supplementation at level B)/(kg of supplement consumed at level A − kg of supplement consumed at level B), where level A is the supplementation rate in a column and level B is the nearest supplementation rate in the column to the left of level A.

5

BW gain tended to increase linearly with increased level of DDG supplementation (P = 0.06; Table 4), indi-

cating supplementation may still be beneficial. Therefore, whether cattle are to be marketed after grazing

Table 5. Cost of additional gain over controls with varying costs for dried distillers grains (DDG) after grazing dormant range and wheat pasture Cost of additional pound of gain,1 $ DDG, $/US ton After grazing range 100 150 200 250 300 After grazing wheat 100 150 200 250 300

0.252

0.50

0.75

0.117 0.176 0.234 0.293 0.351

0.136 0.203 0.271 0.339 0.407

0.148 0.222 0.296 0.370 0.444

2.941 4.412 5.882 7.353 8.824

0.229 0.344 0.459 0.573 0.688

0.292 0.439 0.585 0.731 0.877

For after grazing range values, cost calculated as [1/supplement efficiency (Table 2)]/908 × DDG cost × 0.454. For after grazing wheat values, cost calculated as [1/ system supplement efficiency (Table 4)]/908 × DDG cost × 0.454.

1


2

dormant range or retained to graze wheat pasture should be considered when deciding on the supplementation strategy.

Economic Analysis In addition to supplement efficiency, the cost and net returns of additional gains attributable to supplementation were calculated. The costs of the additional ADG resulting from supplementing with DDG for varying costs of DDG are shown in Table 5. After the rangeland-grazing phase, the cost of the additional ADG was the lowest for the 0.25% of BW group, reflecting the relatively large ADG response. As the level of supplemental feeding increased, the cost of added ADG increased, once again reflecting the diminished ADG response with incrementally higher feeding rates. The cost of additional ADG from supplementation during the rangeland phase had increased considerably after the cattle had completed the wheatgrazing phase (Table 5). Compensatory gains on wheat pasture by the

602

Jenkins et al.

Table 6. Net returns of the supplementation program after grazing dormant range and supplementing dried distillers grain (DDG) when varying DDG costs and value of added BW gain1 Value of added BW, $/pound Level of supplementation2

DDG, $/US ton

$0.70

$0.90

$1.10

$1.30

0.25% BW

100 150 200 250 300

15.66 14.09 12.52 10.94 9.37

21.04 19.47 17.89 16.32 14.75

26.41 24.84 23.27 21.69 20.12

31.79 30.21 28.64 27.07 25.49

0.50% BW

100 150 200 250 300

26.24 23.09 19.94 16.79 13.64

35.53 32.38 29.23 26.08 22.94

44.83 41.68 38.53 35.38 32.23

54.12 50.97 47.82 44.67 41.53

0.75% BW

100 150 200 250 300

35.26 30.54 25.82 21.09 16.37

48.04 43.32 38.59 33.87 29.14

60.82 56.09 51.37 46.64 41.92

73.59 68.87 64.14 59.42 54.69

Calculated as additional BW = [total BW gain of supplemented group − total BW gain of nonsupplemented group (Table 4)]/0.454. Net income attributable to supplementation = [additional BW × the value of added BW] − [additional BW × cost of additional pound of BW gain (Table 5)].

1


2

control group offset all the additional ADG from supplementation during the rangeland phase at the 0.25% of BW treatment level, which is reflected in high costs of additional gain during the wheat-grazing phase. In addition, the compensatory gain on wheat pasture resulted in the cost of the net added ADG from rangeland supplementation at the 0.50 and 0.75% of BW levels being increased by 69 and 98%, respectively. Feasibility of the supplementation program depends on both the cost of additional ADG and the value of the additional ADG. The net returns of the supplementation program with varying DDG costs and value of additional BW after grazing dormant range and wheat pasture are shown in Tables 6 and 7, respectively. After range grazing, the 0.75% of BW group had the highest returns regardless of DDG cost or the value of added BW (Table 6). However, after wheat pasture grazing, the optimal level of supplementation to maximize

net income to supplementation was sensitive to changes in DDG costs (Table 7). In marketing situations in which delivered DDG costs were low ($100/US ton), supplementing DDG at 0.75% of BW maximized net income of the supplementation program. Supplementing DDG at 0.50% of BW maximized net returns to supplementation in all other marketing scenarios. In this data set, DDG cost was the only consideration in determining which level of DDG to supplement if steers were to be marketed after wheat grazing. The 0.25% of BW supplement treatment resulted in negative net returns regardless of DDG cost or the value of additional BW because of the compensatory gain by the nonsupplemented group. Supplementing at 0.50% of BW may be considered the most conservative approach because it was the only level of DDG supplementation that never resulted in negative net returns to supplement in the marketing scenarios described herein.

IMPLICATIONS Supplementing corn DDG on native range in the Texas Panhandle efficiently improves ADG. If weaned calves are grazed on native range and sold before wheat pasture grazing, 0.75% of BW DDG supplementation may provide the most economically beneficial DDG supplementation strategy. However, if calves are retained on wheat pasture and sold in the spring, the maximum net return from DDG supplementation may be sensitive to DDG cost. Supplementing DDG at 0.50% of BW may provide the lowest risk across all steer marketing and DDG purchasing scenarios evaluated. These data demonstrate that the optimal level of DDG supplementation in a given production system is dependent on marketing strategy and DDG cost. This is useful because the price of DDG can be determined before deciding to supplement on dormant range,

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Table 7. Net returns of the supplementation program after grazing wheat pasture and supplementing with dried distillers grains (DDG), when varying DDG costs and value of added BW gain1 Value of added BW, $/pound Level of supplementation2

DDG, $/US ton

$0.70

$0.90

$1.10

$1.30

0.25% BW

100 150 200 250 300

−2.47 −4.09 −5.71 −7.33 −8.95

−2.25 −3.87 −5.49 −7.11 −8.73

−2.03 −3.65 −5.27 −6.89 −8.51

−1.81 −3.43 −5.05 −6.67 −8.29

0.50% BW

100 150 200 250 300

12.96 9.80 6.64 3.49 0.33

18.46 15.31 12.15 8.99 5.83

23.97 20.81 17.66 14.50 11.34

29.48 26.32 23.16 20.01 16.85

0.75% BW

100 150 200 250 300

13.20 8.46 3.73 −1.00 −5.74

19.67 14.94 10.21 5.47 0.74

26.15 21.42 16.68 11.95 7.21

32.63 27.89 23.16 18.42 13.69

Calculated as additional BW = [total BW gain of supplemented group − total BW gain of nonsupplemented group (Table 4)]/0.454. Net income attributable to supplementation = [additional BW × the value of added BW] − [additional BW × cost of additional pound of BW gain (Table 5)].

1


2

whereas the value of added BW may not be known.

LITERATURE CITED Bodine, T. N., and H. T. Purvis II.. 2003. Effects of supplemental energy and/or degradable intake protein on performance, grazing behavior, intake, digestibility, and fecal and blood indices by beef steers grazed on dormant native tallgrass prairie. J. Anim. Sci. 81:304. Drouillard, J. S., C. L. Ferrell, T. J. Klopfenstein, and R. A. Britton. 1991. Compensatory growth following metabolizable protein or energy restrictions in beef steers. J. Anim. Sci. 69:811. Geisert, B. G., T. J. Klopfenstein, D. C. Adams, and J. C. MacDonald. 2007. Comparison of in vivo digestibility to in vitro digestibility of five forages fed to steers. Nebraska Beef Cattle Rep. MP 90-A:109. Greenquist, M. A., T. J. Klopfenstein, G. E. Erickson, and M. K. Luebbe. 2008. Dried distiller’s grains supplementation to yearling cattle grazing smooth bromegrass: Response and performance profile summary. Nebraska Beef Cattle Rep. MP91:27. Griffin, W. A., V. R. Bremer, T. J. Klopfenstein, L. A. Stalker, L. W. Lomas, J. L.

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