As the corn milling industries have continued to expand production, interest in using coproducts of these processes as livestock feedstuffs has also increased.
Many research trials, particularly at Midwest universities, are being conducted to determine the proper use of these feedstuffs to optimize animal performance.
One such experiment, reported in the 2002 Nebraska Beef Report, was conducted by Hushton Block, graduate student; Casey Macken, research technician, and Terry Klopfenstein, professor in the animal science department at the University of Nebraska, Lincoln, and Rob Cooper and Rick Stock of Cargill Corn Milling, Blair, Neb.
The objectives of their research were to determine the optimum level of corn steep liquor to include in yearling steer finishing diets based on steam-flaked corn and corn bran and to determine the optimum level of wet corn gluten feed (WCGF) and crude protein (CP) to include in steam-flaked corn finishing diets for steer calves.
According to the researchers, corn steep liquor (with or without distiller solubles) and corn bran (with or without solvent-extracted germ meal) are the primary components of WCGF. They said WCGF alleviates acidosis in dry-rolled corn finishing diets, thereby improving performance. Also, they noted that both steep liquor and WCGF supply degradable intake protein (DIP) as true protein, which may also improve performance compared to urea.
Procedures
Trial 1. Block et al. used 93 yearling steers in a 104-day finishing trial to investigate the effects of steep liquor inclusion level in steam-flaked corn! corn bran-based diets. They pointed out that the steep used in this trial was a combination of steep liquor and distillers solubles.
Treatments for this trial consisted of adding steep at 0, 10 and 20% of dietary dry matter (DM). Twelve pens of steers with seven or eight steers per pen were randomly allotted to the three treatments, resulting in four replicates per treatment, Block et al. said.
Trial 1 diets were formulated to contain (DM basis) a minimum of 13.0% CP, 0.70% calcium, 0.35% phosphorus and 0.70% potassium and included 27 g per ton monensin and 10 g per ton tylosin. Steers were adapted to the final diet by using four adaptation diets containing alfalfa hay at 45, 35, 25 and 15% of DM for three, four, seven and seven days, respectively. Steers were implanted and treated for internal and external parasites on day 1.
Trial 2. In this trial, Block et al. used 18 individually fed yearling steers in a 154-day individual feeding trial to investigate the effect of steep inclusion in steam-flaked corn/corn bran-based diets. Treatments consisted of adding steep at 0 or 10% of diet DM.
Trial 2 diets were formulated to contain a minimum of 13.4% CP, 0.70% calcium, 0.35% phosphorus and 0.70% potassium and included 28 g per ton monensin and 10 g per ton tylosin. Steer intakes were started at 11 lb. DM per day and increased 0.5 lb. DM per day to ad libitum intake Trial 2 steers were implanted on day 1 and re-implanted on day 41.
Trial 3. To investigate the effects of WCGF and CP levels in steam-flaked corn-based diets, the researchers used 360 steer calves in a 166-day finishing trial. They said treatments for this trial consisted of adding WCGF at 0, 20, 30 and 40% and CP levels of 13.0, 13.7 and 14.4% of diet DM. Block et al. pointed out that these CP levels were achieved with urea supplementation.
The researchers noted that the combination of 40% WCGF and 13.0% CP was infeasible due to the CP content of the feed ingredients, which, along with pen availability, resulted in the exclusion of this combination.
According to the report, CP variation in the feed ingredients resulted in 'higher-than-anticipated CP levels' (as reflected in the column headings for Table 2).
The researchers said the diets for this trial were formulated to contain (DM basis) a minimum of 0.70% calcium; 0.35% phosphorus and 0.70% potassium and included 27 g per ton monensin and 10 g per ton tylosin. Steers were vaccinated for respiratory disease, treated for internal and external parasites and implanted on day 1. On day 70, steers were retreated for external parasites and re-implanted.
Results
Trial 1. The researchers reported that the inclusion of steep at 0, 10 or 20% of diet DM did not affect (P > 0.05) feedlot performance or measured carcass evaluation variables (data not shown).
However, they noted that observed numerical differences suggested that hot carcass weight (HCW), average daily gain (ADG) and feed efficiency tended toward quadratic patterns in response to increased levels of steep inclusion. Block et al. said there was a numerical benefit in HCW (+3%), ADG (+9%) and feed efficiency (+5%) to increasing the inclusion of steep from 0 to 2 10% of DM. Conversely, they noted that increasing steep from 10 to 20% resulted in reduced ADG (-1%), no benefit for HCW (0%) and decreased feed efficiency (-3%).
Trial 2. The inclusion of steep at 10% of diet DM did not affect (P > 0.05) the feedlot performance parameters in this trial, Block et al. pointed out (Table 1). Similar to the trend observed in trial 1, they said the observed numerical values for feed efficiency in trial 2 tended to be improved with inclusion of steep at 10% of diet DM.
Therefore, Block et al. concluded that the results of these trials suggest that the inclusion of steep at 10% of diet DM in steam-flaked corn/corn bran-based finishing diets may be beneficial in improving feed efficiency.
Trial 3. For the third trial, the researchers reported that HCW, ADG and feed efficiency (Table 2) responded to increasing levels of WCGF in a quadratic fashion (P < 0.05) and dry matter intake (DMI) responded in a linear fashion (P < 0.05).
As a result of increasing CP levels, HCW, ADG and feed efficiency responded in a linear fashion (P < 0.05), the researchers said.
According to the researchers, net energy (NE) levels for trial 3 were calculated from feed energy values (Table 3). They conducted a nonlinear analysis using the 20 and 30% WCGF levels, and they determined a breakpoint of 8.6% DIP for ADG and 8.4% DIP for feed: gain.
The researchers predicted metabolizable protein and DIP levels for trial 3 (Table 3) according to the 2000 National Research Council (NRC) beef model using microbial efficiency values determined by balancing DIP requirements. They said inadequate DIP supply was indicated for 20% WCGF at 13.4% CP and 30% WCGF at 13.5% CP.
According to Block et al., the NRC predictions suggested that the CP requirement for the 20 and 30% WCGF levels was approximately 13.7%. There was a small response in efficiency (Table 2) for the 20% level of WCGF when CP was increased to levels more than 14.1%, but no response occurred with a similar increase for the 30% WCGF level, they said.
Block et al. said these results indicate that the level of WCGF to include in steam-flaked corn-based finishing diets to optimize ADG, feed efficiency and HCW of steer calves is in the range of 20-30% of dietary DM.
The researchers noted that the effect of WCGF on observed mean animal performance responses should only be evaluated at the higher CP levels where DIP is not limiting. Predicted treatment means were remarkably similar for HCW and ADG (not shown) between the 20 and 30% WCGF treatments.
Additionally, they said, if WCGF is priced lower than corn, WCGF's lower price may justify higher inclusion levels as the economic benefits may outweigh small performance losses.
The research group said it did not determine the optimal CP level in trial 3 as responses to supplemental CP were linear. However, the group noted that it could appear to be as high as 15.0% CP, which was the highest level evaluated.
Effect of steep liquor on feedlot performance Standard Steep liquor 0% 10% error P-value Initial weight, lb. 758 773 22 0.66 Final weight, lb. 1,219 1,226 33 0.87 ADG, lb. 3.01 2.97 0.15 0.83 DMI, lb. per day 21.8 20.9 0.55 0.26 Feed:gain 7.30 7.11 0.21 0.53 Effect of WCGF and CP level on feedlot performance WCGF 0% 20% CP 13.9% 13.4% 14.1% 14.8% Initial weight, lb. 635 635 635 632 ADG, lb. (a,b) 3.42 3.55 3.69 3.79 DMI, lb. per day (c) 19.8 20.1 20.6 21.1 Feed:gain (a,b) 5.80 5.65 5.60 5.56 HCW, lb. (a,b) 776 792 806 815 Fat thickness, in. 0.48 0.47 0.46 0.50 Marbling (d) 529 539 522 541 Ribeye area, sq. in. 13.2 13.7 13.4 13.7 Yield grade 2.23 2.27 2.21 2.30 Choice and Prime, % (e) 64.1 65.8 66.7 80.0 WCGF 30% 40% CP 13.5% 14.2% 14.9% 14.5% Initial weight, lb. 633 633 634 634 ADG, lb. (a,b) 3.45 3.76 3.65 3.51 DMI, lb. per day (c) 20.6 21.3 20.6 20.7 Feed:gain (a,b) 5.97 5.66 5.66 5.90 HCW, lb. (a,b) 779 812 802 786 Fat thickness, in. 0.47 0.52 0.48 0.44 Marbling (d) 529 548 522 503 Ribeye area, sq. in. 13.1 13.5 13.9 13.6 Yield grade 2.30 2.57 2.23 2.13 Choice and Prime, % (e) 52.5 71.8 64.1 50.0 WCGF 40% Standard CP 15.0% error Initial weight, lb. 634 1.1 ADG, lb. (a,b) 3.57 0.08 DMI, lb. per day (c) 20.9 0.3 Feed:gain (a,b) 5.85 0.10 HCW, lb. (a,b) 793 8 Fat thickness, in. 0.51 0.02 Marbling (d) 540 13 Ribeye area, sq. in. 13.5 0.2 Yield grade 2.44 0.11 Choice and Prime, % (e) 69.2 -- (a)Quadratic effect of WCGF level (P < 0.05). (b)Linear effect of CP level (P < 0.05). (c)Linear effect of WCGF level (P < 0.05). (d)Marbling score: 500 = small (low choice), 600 = modest (average choice). (e)Not analyzed for effect of WCGF or CP level. Predicted energy and protein levels for trial 3 WCGF -0% 20% CP 13.9% 13.4% 14.1% 14.8% [NE.sub.maintenance] 1.04 1.03 1.03 1.03 [NE.sub.gain] 0.72 0.72 0.71 0.71 Metabolizable protein, g per day Supplied 802 865 884 903 Required 745 764 784 798 Balance 57 101 100 105 DIP, g per day Supplied 808 742 827 917 Required 706 754 771 788 Balance 102 -12 56 129 WCGF 30% 40% CP 13.5% 14.2% 14.9% 14.5% [NE.sub.maintenance] 1.03 1.03 1.02 1.02 [NE.sub.gain] 0.71 0.71 0.71 0.70 Metabolizable protein, g per day Supplied 910 939 906 934 Required 749 794 779 759 Balance 161 145 127 175 DIP, g per day Supplied 755 849 888 838 Required 791 816 787 809 Balance -36 33 101 29 WCGF 40% CP 15.0% [NE.sub.maintenance] 1.02 [NE.sub.gain] 0.70 Metabolizable protein, g per day Supplied 941 Required 767 Balance 174 DIP, g per day Supplied 897 Required 815 Balance 82
