Effects of Distillers Dried Grains with Solubles as a Protein Source in a Creep Feed. 1. Suckling Calf and Dam Performance
P. A Lancaster, J. B. Corners, L. N. Thompson, M. R. Ellersieck, and J. E. Williams
Department of Animal Sciences, University of Missouri, Columbia 65211
ABSTRACT
A 2- yr study was performed to evaluate the effect of corn distillers dried grains with solubles (DDGS) vs. soybean meal (SBM) as the protein source in a creep feed. Thirty-six steer calves were used in each of the 2 yr to compare the performance of traditionally noncreep-fed, control weaned calves with those offered creep feed with either DDGS or SBM beginning 68 d prior to weaning. The creep supplements consisted of a 2:1 ratio of soy hulls and cracked corn with the protein source. In yr 1 and 2, creepfed steers had greater (P < 0.01) ADG than noncreep-fed steers (1.0 vs. 0.7 kg/d and 1.0 vs. 0.9 kg/d in yr 1 and 2, respectively); however, weaning weights were only greater (P < 0.05) in yr 1 (231.0 vs. 206.0 kg, respectively). In both years, protein source had no effect (P > 0.10) on ADG, supplemental DMI, and supplemental feed efficiency. In yr 1, cost per kilogram of supplemental gain for DDGS tended to be less (P < 0.10) than SBM steers ($0.89 vs. $1.07, respectively). In spite of this fact, the total supplemental feed cost was lower (P < 0.01) in yr 2 for DDGS vs. SBM steers ($13.88 vs. $18.30 per head, respectively), even though supplemental DMI and supplemental gain were not different between treatments. In conclusion, when used in a creep feed, DDGS provided similar performance at a lower cost as compared with SBM; both protein sources in a creep ration increased ADG of calves.
INTRODUCTION
Corn distillers dried grains with solubles (DDGS) originates as a coproduct of ethanol production. Its highly digestible fiber content and high ruminally undegradable protein (RUP) content make it an excellent supplement for growing calves. Approximately 52% of the protein in DDGS is ruminally undegradable (NRC, 2000). This characteristic provides ruminants with an excellent source of amino acids for absorption in the small intestine. Supplementation of DDGS increased ADG of steers grazing medium- quality native summer range (Karges et al., 1992).
After 90 d of lactation, a greater proportion of the calf’s nutrient intake is supplied by forage (Hollingsworth- Jenkins, 1994; Loy et al., 2002). For a spring calving herd, the forage quality of pasture declines as summer progresses while nutrient requirements of the calf rapidly increase. Providing a creep ration to nursing calves grazing forage has been an excellent management strategy to increase weaning weight (Martin et al., 1981). Nursing calves have a higher protein requirement because the rate of lean tissue growth is greatest at an early age (Black and Griffiths, 1975). Consequently, feeding a source of protein with a greater proportion of RUP may increase postruminal supply of limiting amino acids for growth in nursing calves grazing medium-quality native grass (Hollingsworth- Jenkins, 1994), thus increasing lean tissue accretion. Thomas (1986) stated that creep feeding would be profitable when calf prices are high relative to feed costs. Since DDGS is economically priced as a protein source, its use as a protein source may be a management strategy that lowers creep feed costs and improves gain of nursing calves.
Several reports have evaluated DDGS as a protein source for grow ing calves (Willis et al., 1981; Corners, 2004) as well as a protein source in a creep ration (Reed et al., 2006). In this study, the objective of this experiment was to compare DDGS vs. soybean meal (SBM) as protein and energy source in a creep ration for nursing steer calves as well as the subsequent performance of these calves in the feedlot.
MATERIALS AND METHODS
Animals and Management
Thirty-six steer calves with dams were used each year of a 2-yr study to test the effects of DDGS as a protein source in a creep feed. Only steers from dams of 3 yr of age or older were used. Steers originated from 4 sires in yr 1, but sires were not equally represented in each treatment or pasture. However, in yr 2, steers originated from 4 sires that were equally represented within treatments by design but not within pasture. Each year was divided into 2 phases: a creep and a feedlot phase. The feedlot phase will be presented in a companion paper.
In yr 1, steers (159.9 ± 26.9 kg initial BW) were allotted by age (122.4 ± 17 d) to 1 of 6 4-ha pastures with 2 pastures per treatment. In yr 2, steers (184.3 ± 12.8 kg initial BW) were blocked by age (148.3 ± 5.4 d) and sire and randomly assigned to treatments.
There were 2 sires with 2 blocks of steers and 2 sires with 4 blocks. Blocks were randomly assigned to 3 of the endophyte-free tall fescue pastures used in yr 1. Thus, in yr 2 each sire and pasture were equally represented within each treatment.
The experimental design was changed from yr 1 in an attempt to separate the effects of DDGS and SBM, which was the main objective of this study. For yr 2, these changes in design eliminated the effects of calf sire and calf age, as well as pasture quality and quantity on dietary treatment.
TABLE 1. Creep supplements fed to steers
| Year 1 | Year 2 | |||
|---|---|---|---|---|
| SBM¹ | DDGS | SBM | DDGS | |
| Ingredient, % of DM | ||||
| Cracked corn | 28.04 | 20.04 | 26.45 | 19.78 |
| Soybean hulls | 57.14 | 45.26 | 54.14 | 40.68 |
| DDGS | --- | 32.92 | --- | 33.23 |
| SBM | 14.04 | --- | 13.13 | --- |
| Limestone | 0.78 | 0.79 | 2.01 | 2.47 |
| Dicalcium phosphate | --- | --- | 2.61 | 2.18 |
| Molasses | --- | --- | 1.66 | 1.67 |
| Trace Mineral² | --- | --- | --- | --- |
| Chemical analysis | ||||
| DM, % | 87.76 | 88.26 | 86.90 | 87.24 |
| NDF, % of DM | 43.87 | 52.13 | 50.15 | 52.09 |
| CP, % of DM | 16.99 | 17.00 | 15.32 | 13.72 |
| RUP,³ % of CP | 41.12 | 56.90 | 39.71 | 48.63 |
| NEm, Mcal/kg DM | 2.04 | 2.07 | 1.94 | 1.97 |
| NEm, Mcal/kg DM | 1.38 | 1.41 | 1.31 | 1.34 |
¹SBM = soybean meal; DDGS = distillers dried grains with solubles.
²The trace mineral provided 100 g of Fe/kg, 100 g of Mn/kg, 100 g of Zn/kg,
20 g of Cu/kg, 500 mg of Co/kg, 1,000 mg of I/kg.
³RUP = ruminally undegradable protein.
The treatments were 1) noncreep fed (control); 2) creep-fed with DDGS; or 3) creep-fed with SBM as the protein sources. Creep supplements were formulated to contain similar levels of CP and energy with DDGS and SBM supplying similar amounts of CP but different amounts of RUP (Table 1). Creep supplements consisted of soybean hulls and cracked corn in a 2:1 ratio with the protein source. Trace minerals were provided as a block in each pasture. In yr 1, white granular salt was added to the diet in an attempt to limit intake to approximately 1.6 to 2.0 kg/d of DM per head. Salt content was increased from 0 to 12% of the supplement (as-fed basis) as the creep phase progressed. In yr 2, salt was not used because calves were individually hand-fed their supplements to limit the variation in DM intake. Steers were individually fed their respective supplements daily starting July 23, 2003. Steers were sorted from dams, placed in individual stanchions, and allowed 30 min to consume a maximum of 1.8 kg/d of DM per head. Intake was limited in each of the 2 yr because previous research has shown that limiting the intake of creep supplement reduces forage substitution and improves supplemental efficiency (Cremin et al., 1991; Faulkner et al., 1994) and, most likely, profitability.
In yr 1, endophyte-free tall fescue pastures were strip-grazed by the use of 5-cm wide, white electric fence tape. Cattle were confined to 0.81 ha at the start of the study and given an additional 0.40 ha when forage was grazed to an average observed height of 8 to10 cm. This continued throughout the course of the creep phase of the study. Creep feeders were placed 23 m from the automatic drinkers in each pasture that required a feeder. In yr 2, initial grazing allowance was increased to 1.62 ha because twice the number of cow-calf pairs were located on each endophyte- free tall fescue pasture. Since yr 2 was a dry year, cow-calf pairs grazed for only 36 d and then were fed low-endophyte tall fescue hay the remainder of the 69 d of the creep phase. During the time cowcalf pairs were fed hay, dams were supplemented with 1.2 kg/d of DM per head of 1:1 ratio of soybean hulls and whole shelled corn to maintain body condition. The supplement provided 9.2% CP and 2.1 Mcal/kg of NEm and 1.4 Mcal/kg of NEg. Supplement was fed to dams while steers were in feeding stanchions so that the supplement was not available to the steers.
In both years, BW of steers were taken on 2 consecutive days at the start and end of the creep phase. Steers were sorted and penned separately from dams for approximately 16 h without feed or water prior to recording shrunk weights. The body condition score (BCS) of dams was taken by 2 trained technicians at the start and end of the creep phase.
Sample Collection and Analysis
Forage samples were taken at the start of the creep phase and for each additional acre of new forage at the time pairs were permitted to graze the new forage. Forage samples were taken by casting a 0.1 m2 square randomly about the pasture so that 12 samples/ha were collected. Forage samples were cut within 2.5 cm of the ground with the use of hand-held grass clippers. A composite was made of all forage samples taken from a single pasture at a given sampling time. The composite was dried in a 55°C oven for 72 h to determine forage DM. The sample was chopped, ground (Wiley Mill, Thomas Scientific, Swedensboro, NJ) to pass through a 5-mm screen, and thoroughly mixed, and then a subsample was ground to pass through a 2-mm screen for subsequent analysis.
In both years, samples of the mixed supplements were taken weekly from each treatment. The mixed supplement samples were thoroughly mixed and ground (Wiley Mill) to pass through a 2-mm screen for subsequent analysis.
All previously ground supplement and forage samples were analyzed for DM (AOAC Official Method 978.10; AOAC, 1995), N content by combustion analysis (LECO Instruments, Inc., St. Joseph, MI; AOAC Official Method 990.03; AOAC, 1995), and NDF (Van Soest et al., 1991).
Calculations
Available forage was determined by multiplying the quantity of forage DM in the square quadrant by the number of forage squares constituting a hectare. The samples were taken before the cattle were allowed to graze the sections of pasture. Supplemental gain was the total gain of creep-fed treatments minus the total gain of the control treatment. Supplemental gain to feed ratio was the amount of supplemental gain divided by creep supplement intake. The cost per kilogram of supplemental gain was calculated as the total feed costs divided by the amount of supplemental gain. Gross weaning revenue was calculated as the gross income generated from steers at weaning minus the total feed costs incurred during the creep phase. The gross income generated from steers was calculated as price per kilogram multiplied by the weaning weight. The prices used to calculate the gross income from the marketing of steers at weaning were acquired from a local livestock auction and were adjusted for different weight groups. Steers ranging from 180 to 230, 230 to 270, and 270 to 320 kg were assigned prices of $1.96, $1.93, and $1.84/kg, respectively, in yr 1. The same 3 weight ranges were assigned prices of $2.42, $2.35, and $2.27/kg, respectively, in yr 2.
Statistical Analysis
In yr 1, data were analyzed as a completely randomized design using the GLM procedure of SAS (SAS Inst. Inc., Cary, NC). For data with animal measurements, treatment and pasture within treatment were included in the model, using pasture within treatment as the error term to test treatment means. For data with only pasture measurements and data calculated in reference to the control treatment, pasture means were used and only treatment was included in the model using the overall error term to test treatment means. Pasture quantity and quality measurements were analyzed as a split-plot in time design using the mixed procedure of SAS. The effects of treatment were tested using pen within treatment as the error term, and the effects of time and treatment by time were tested using the subplot error term. This procedure also allowed comparison of treatment means at each time point, which were separated using Fisher’s LSD. Since there was no treatment by time interactions (P > 0.10), data were pooled and overall treatment means presented.
In yr 2, data were analyzed as a randomized complete block design using the GLM procedure of SAS. For data calculated in reference to the control treatment, the mean of the 4 animals within each treatment within each pasture was used. Pasture was the blocking factor instead of steer age, with pasture and treatment included in the model using the overall error term to test treatment means. For all other data, steer age was the blocking factor with age-sire block and treatment included in the model using the overall error term to test treatment means. All treatments were represented in each pasture; thus split-plot analysis was not performed on pasture quality and quantity in yr 2.
Orthogonal contrasts of preplanned treatment comparisons were used to separate treatment means in both years. Contrasts were creep fed vs. noncreep-fed and SBM vs. DDGS.
TABLE 2. Forage quality and availability during the creep phase in year 1
| Contrast (P =)³3 | ||||||
|---|---|---|---|---|---|---|
| Control | DDGS¹ | SBM | SEM² | S vs. D | C vs. NC | |
| DM, %† | ||||||
| Overall average | 30.7 | 32.5 | 31.1 | 1.9 | 0.50 | 0.57 |
| CP, % of DM | ||||||
| Overall average | 11.5 | 11.8 | 13.2 | 0.8 | 0.32 | 0.36 |
| NDF, % of DM† | ||||||
| Overall average | 68.6 | 67.7 | 65.6 | 1.5 | 0.57 | 0.56 |
| Forage availability, kg DM/ha† | ||||||
| Overall average | 3,505 | 3,741 | 3,722 | 293 | 0.95 | 0.44 |
¹DDGS = distillers dried grains with solubles; SBM = soybean meal.
²Greatest standard error of mean (SEM) for contrasts reported.
³S = soybean meal, D = distillers dried grains, C = creep fed, NC = noncreep fed.
†Time effect (P < 0.01).
RESULTS AND DISCUSSION
Since there was no treatment by time interactions for forage quality and quantity, the data were pooled to present an overall mean of treatments. As shown in Table 2 for yr 1, clipped pasture samples had an average DM of 30.7, 32.5, and 31.0%, an average CP of 11.5, 11.8, and 13.0%, and an average NDF of 68.6, 67.7, and 65.6% for control, DDGS, and SBM, respectively, with no difference in DM, CP, and NDF among treatments. The average forage availability did not differ among treatments (3,504, 3,741, and 3,721 kg of DM/ha for control, DDGS, and SBM, respectively).
As shown in Table 3 for yr 1, the protein sources (DDGS vs. SBM) in the creep ration had no effect (P ≥ 0.45) on ADG, total gain, and weaning weight. However, creepfed steers had increased (P < 0.001) ADG compared with noncreep-fed steers (1.0 vs. 0.7 kg/d, respectively), which led to heavier (P < 0.05) weaning weights for creepfed steers (231.0 vs. 206.6 kg, respectively). The DM intake (2.06 and 1.78 kg/d, respectively) and supplemental weight gain (23.1 and 19.4 kg, respectively) were not different (P > 0.10) between DDGS and SBM, leading to no differences (P > 0.10) in supplemental gain to feed ratio for DDGS and SBM steers (0.16 and 0.16, respectively).
In contrast to these findings, Hollingsworth- Jenkins (1994) found that calves fed a creep ration with the RUP source included as heattreated SBM had greater ADG as compared with those fed a creep ration containing wheat gluten and soy hulls as a rumen-degradable protein source. Similar to this study, Cremin et al. (1991) observed no effect of RUP in a limit creep feed on ADG as compared with a limited high-protein treatment. These authors inferred that under these conditions, energy rather than protein limited growth of nursing calves, which is similar to the results of Loy et al. (2002). In agreement with this study, Reed et al. (2006) observed no difference in performance of nursing calves fed creep rations of DDGS vs. SBM as the protein sources. In our study, the lack of differences in ADG between DDGS and SBM suggests that protein supply of amino acids postruminally were not limiting for growth, but rather energy was more limiting for the growth of the nursing calves.
Similar to the results from this study, others (Martin et al., 1981; Faulkner et al., 1994) have observed that creep feeding vs. noncreep feeding usually increased ADG and weaning weights. In addition, limiting daily intake of creep feed with salt, as used in this study, usually improves the supplemental feed efficiency (Lusby, 1985, Kunkle et al., 1991).
The cost per kilogram of supplemental gain tended to be lower (P < 0.10) for steers creep fed DDGS vs. SBM in yr 1, which was attributed to the lower cost of DDGS compared with SBM ($105 vs. $328/metric ton, respectively). Despite the lower cost per kilogram of supplemental gain for DDGS in the creep ration, protein source had no effect (P > 0.50) on total feed cost ($20.43 vs. $20.88/hd, respectively) or gross revenues ($423.63 vs. $426.26, respectively). Likewise, in yr 1, gross revenues ($425.43 vs. $402.46, respectively) generated from weaned calves creep vs. noncreep fed were not different (P > 0.20). One may infer from these data that creep feeding with the DDGS and SBM supplements significantly improved ADG and weaning weight of calves; however, when feed costs and the current market price were considered, it was not profitable to sell these calves at weaning.
TABLE 3. Performance of steers and dams during the creep phase in year 1
| Contrast (P=)³ | |||||||
|---|---|---|---|---|---|---|---|
| Control | DDGS¹ | SBM | SEM² | S vs. D | C vs. NC | ||
| Steer performance | |||||||
| Initial weight, kg | 157.8 | 158.2 | 163.7 | 10.98 | 0.62 | 0.74 | |
| Weaning weight, kg | 206.6 | 230.1 | 231.9 | 13.56 | 0.90 | 0.05 | |
| Total gain, kg | 48.8 | 71.9 | 68.2 | 4.84 | 0.45 | <0.001 | |
| ADG, kg/d | 0.7 | 1.1 | 1.0 | 0.07 | 0.46 | <0.001 | |
| Supplement DMI, kg/d | 2.06 | 1.78 | 0.31 | 0.53 | |||
| Supplemental gain, kg | 23.1 | 19.4 | 4.23 | 0.39 | |||
| Supplemental gain:feed, kg/kg | 0.16 | 0.16 | 0.01 | 0.89 | |||
| Cost/kg supplemental gain, $ | 0.89 | 1.07 | 0.04 | 0.09 | |||
| Total feed costs, $ | 20.43 | 20.88 | 4.12 | 0.92 | |||
| Gross weaning revenue, $† | 402.46 | 423.63 | 426.26 | 24.58 | 0.92 | 0.37 | |
| Dam performance | |||||||
| Initial BCS‡ | 4.8 | 5.2 | 5.1 | 0.3 | 0.62 | 0.09 | |
| Final BCS | 4.3 | 4.7 | 4.6 | 0.2 | 0.77 | 0.16 | |
| BCS change | -0.5 | -0.5 | -0.5 | 0.1 | 0.62 | 0.35 | |
¹DDGS = distillers dried grains with solubles; SBM = soybean meal.
²Greatest standard error of means (SEM) reported.
³S = SBM; D = DDGS; C = creep-fed; NC = noncreep-fed.
†Gross weaning revenue is gross income at weaning minus feed costs and all other costs assumed equal among treatments.
Prices were acquired from a local livestock auction company. The prices used were $1.96, $1.93, and $1.84/kg for live
weights of 180 to 230, 230 to 270, and 270 to 320 kg, respectively.
‡BCS = body condition score.
In yr 2, all treatments were represented in each pasture; thus treatment means for chemical composition of pastures could not be separated. In Table 4, the average DM, CP, and NDF contents of forage samples were 45.8 ± 8.2%, 8.6 ± 1.2%, and 69.0 ± 2.9%, respectively, whereas forage availability in each of the 3 pastures averaged 1,622 ± 608 kg DM/ha. The composition of the forage suggests that the forage was marginal in supply of CP. The forage availability in yr 2 was only 44% of that in yr 1, requiring hay supplementation to the cow-calf pairs and corn and soyhull mix to the dams during the last 33 of the 69-d creep period. The CP content of the hay (9.1 ± 1.3%) supplemented to the dams and calves was not different from that of the forage, whereas NDF content (76.6 ± 2.1%) of the hay was higher than that of the forage.
As observed in yr 1, protein source had no effect (P ≥ 0.50) on ADG or weaning weight of steers (Table 5). As observed in yr 1, creep feeding increased (P < 0.01) ADG and total gain as compared with the noncreep-fed treatment; but creep feeding did not affect (P = 0.34) weaning weight of calves. Unlike those differences in weaning weight between creep and noncreep-fed calves for yr 1, the lack of an effect of creep feeding on weaning weight in yr 2 was attributed to the lower supplemental gains of steers. The low supplemental gain of creep-fed calves was attributed to the feeding of the creep ration for 30 min in yr 2, which most likely resulted in the numerically lower supplemental DMI in yr 2 vs. yr 1 (1.4 vs. 1.9 kg/d, respectively). No differences (P = 0.34) in DMI (1.33 and 1.41 kg/d, respectively) and total supplemental weight gain (10.1 and 9.7 kg, respectively) lead to no differences (P = 0.87) in supplemental gain to feed ratio between protein sources (DDGS and SBM, 0.11 and 0.10, respectively).
Unlike yr 1, the cost of supplemental gain was not different (P = 0.37) for DDGS vs. SBM steers ($2.34 and $4.20/kg of gain, respectively). However, total feed cost was lower (P < 0.001) for DDGS as compared with SBM steers, attributed to DMI (1.33 vs. 1.44 kg/d, respectively) not being different (P = 0.34) and the lower cost of DDGS compared with SBM ($94 and $328/metric ton, respectively) used in the supplements. The differences in the cost of supplemental gain between treatments in yr 1 vs. yr 2 was attributed to the biologically greater supplemental gain of steers fed the DDGS and SBM treatments in yr 1 vs. yr 2. Although not significant, these differences may be attributed to the method of limiting consumption of creep feed to 30 min in yr 2 rather than a 24- h period for consumption of the creep ration in yr 1.
TABLE 4. Forage quality and availability and hay quality during the creep phase in year 2¹
| DM,% | CP, % of DM | NDF, % of DM | Forage availability,² kg DM/ha | |
|---|---|---|---|---|
| Forage; | ||||
| Day 0 | 30±0.7 | 10.4±1.1 | 65.9±2.0 | 1,324±83 |
| Day 8 | 46.6±3.2 | 8.0±0.6 | 67.1±2.7 | 986±32 |
| Day 16 | 47.5±3.9 | 7.7±0.9 | 68.7±0.6 | 1,943±618 |
| Day 21 | 48.1±2.1 | 9.3±0.3 | 68.9±2.9 | 2,593±357 |
| Day 26 | 50.1±5.1 | 8.4±0.2 | 72.6±2.1 | 1,469±369 |
| Day 31 | 52.4±6.7 | 7.6±1.1 | 70.7±2.0 | 1,414±271 |
| Overall average | 45.8±8.2 | 8.6±1.2 | 68.9±2.9 | 1,622±608 |
| Hay | ||||
| Day 36 | 87.5±0.7 | 8.8±0.3 | 75.6±1.9 | --- |
| Day 42 | 77.9±0.1 | 10.6±0.7 | 74.5±0.8 | --- |
| Day 50 | 81.9±2.8 | 9.6±1.9 | 77.7±1.9 | --- |
| Day 60 | 82.3±1.5 | 7.9±0.5 | 77.7±2.0 | --- |
| Overall average | 82.8±3.7 | 9.1±1.3 | 76.6±2.1 | --- |
¹All treatments were represented in each of 3 pastures; thus treatment means could not be separated. All values are mean ±
standard deviation of the three pastures.
²All pastures were supplemented with large round bales of hay as needed. The amount of hay delivered was not recorded.
As observed in yr 1, the gross revenues were not different (P ≥ 0.52) for protein source or creep feeding. Even though the cost of DDGS was considerably less than that of SBM, one may infer from these data that the supplemental gains of steers fed the DDGS and SBM treatments as compared with the noncreep-fed steers were not sufficient to offset the costs of feeding either protein source to creep-fed calves as compared with the noncreep treatment.
In both years, feeding calves a SBM or DDGS creep ration vs. noncreep ration resulted in no difference (P ≥ 0.35) in BCS change of dams during the creep feeding phase. Others (Tarr et al., 1994) also found no effect of creep feeding on BCS change of dams. The lack of changes in BCS over the 2- yr study suggests that forage availability and supplementation of hay and concentrate to cows in yr 2 was sufficient to keep them in similar BCS to those in yr 1.
Previous studies have shown that limit feeding a high CP creep ration efficiently increases weaning weights of spring-born calves (Lusby, 1985; Kunkle et al., 1991). The conversion of CP in a creep ration to supplemental gain was 3.3 to 1 (Lusby et al., 1985), whereas Kunkle et al. (1991) found conversion to supplemental gains of 2 to 1 and 6.5 to 1. Others (Martin et al., 1981; Faulkner et al., 1994) have observed similar differences in ADG and total gain between creep vs. noncreep-fed calves using corn and soy hulls in the creep ration.
During this 2-yr study, limit feeding either DDGS or SBM as a source of RUP or rumen-degradable protein in the creep ration for 69 d increased ADG of nursing calves as compared with the noncreep-fed calves. Even though RUP values were greater for DDGS vs. SBM used in the creep ration, there was no difference in ADG response between protein sources. Previous work (Hollingsworth-Jenkins, 1994) revealed that RUP source resulted in a greater increase in ADG of creep-fed steers as compared with those fed degradable protein supplement, but these supplements were not similar in CP content. Thus, the elicited response of the RUP treatment may have been due to a greater amount of CP in the supplement.
An explanation for the failure to observe differences in ADG between DDGS and SBM may be attributed to the diet not meeting the requirement for most limiting amino acid. According to NRC (2000), the DDGS and SBM creep rations did not fulfill the amino acid requirement of histidine in creep-fed calves grazing forage. Others (Willms et al., 1991; Corners, 2004) revealed that supplementation of either DDGS or SBM included at equal amounts of CP did not increase intestinal flow of histidine in growing calves fed foragebased diets. Furthermore, the rate of gain (1.0 to 1.1 kg/d) may not be sufficient to warrant a need for greater supply of essential amino acids for protein accretion in the creep-fed calves.
Another factor contributing to the difference in weaning weight response of creep fed vs. noncreepfed calves between yr 1 and 2 may be the producing ability of dams. Most probable producing ability is a recommended method for comparing the producing ability of dams of different parities for culling purposes within a herd (Thomas, 1986). In yr 1 and 2, the most probable producing ability of dams nursing noncreep-fed vs. creep-fed calves (99.1 vs. 101.5 and 102.1 vs. 99.9, respectively) appeared to have no effect (P ≥ 0.13) on weaning weight response.
TABLE 5. Performance of steers and dams during the creep phase in year 2
| Contrast (P=)³ | ||||||
|---|---|---|---|---|---|---|
| Control | DDGS¹ | SBM | SEM² | S vs. D | C vs. NC | |
| Steer performance | ||||||
| Initial weight, kg | 187.5 | 180.4 | 184.9 | 9.02 | 0.40 | 0.29 |
| Weaning weight, kg | 248.4 | 251.3 | 255.4 | 10.22 | 0.50 | 0.34 |
| Total gain, kg | 60.8 | 70.9 | 70.5 | 5.84 | 0.91 | <0.01 |
| ADG, kg/d | 0.9 | 1.0 | 1.0 | 0.08 | 0.91 | <0.01 |
| Supplement DMI, kg/d | --- | 1.33 | 1.41 | 0.05 | 0.34 | --- |
| Supplement gain, kg | --- | 10.1 | 9.7 | 2.04 | 0.91 | --- |
| Supplement gain:feed, kg/kg | --- | 0.11 | 0.10 | 0.02 | 0.87 | --- |
| Cost/kg supplemental gain, $ | --- | 2.34 | 4.20 | 1.15 | 0.37 | --- |
| Total feed cost, $ | --- | 13.88 | 18.31 | 0.60 | <0.001 | --- |
| Gross weaning revenue,† $ | 585.05 | 576.58 | 581.13 | 18.79 | 0.68 | 0.52 |
| Dam performance | ||||||
| Initial BCS‡ | 5.1 | 5.0 | 5.0 | 0.4 | 0.93 | 0.73 |
| Final BCS | 4.5 | 4.6 | 4.5 | 0.3 | 0.59 | 0.95 |
| BCS change | -0.6 | -0.4 | -0.5 | 0.2 | 0.35 | 0.59 |
¹DDGS = distillers dried grains with solubles; SBM = soybean meal.
²Greatest standard error of means (SEM) reported.
³S = SBM; D = DDGS; C = creep-fed; NC = noncreep-fed.
†Gross weaning revenue is gross income at weaning minus feed costs and all other costs assumed equal among treatments.
Prices were acquired from a local livestock auction company. The prices used were $2.42, $2.35, and $2.27/kg for live
weights of 180 to 230, 230 to 270, and 270 to 320 kg, respectively.
‡BCS = body condition score.
IMPLICATIONS
The use of DDGS in a creep supplement will maintain similar gains compared with SBM while reducing the cost of feed. The reduction in cost by using DDGS in the creep ration appeared to lower cost per kilogram of supplemental gain. However, gross weaning weight revenue was not different between protein sources. Creep feeding an energy supplement with DDGS or SBM increases BW gains, but increasing weaning weights may depend upon forage quantity and quality as well as the producing ability of the dams. More research is warranted on the economical impact of creep feeding calves from cows differing in milk production.
ACKNOWLEDGMENTS
The authors greatly appreciate the support from Dakota Gold, Sioux Falls, SD and NEMO Grain LLC, Macon, MO for this research project.
LITERATURE CITED
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