With the increased production of ethanol in the Midwest, many corn byproducts have received much attention as potential ingredients for the animal feed industry.
At Kansas State University's 2003 Cattlemen's Day last month, S.P. Montgomery, J.S. Drouillard, J.J. Sindt, M.A. Greenquist, B.E. Depenbusch, E.J. Good, E.R. Loe, M.J. Sulpizio and T.J. Kessen presented research on the use of full-fat corn germ (FFG) as a lipid source in finishing diets containing steam-flaked corn as well as the effects of added vitamin E in finishing diets containing various concentrations of added fat on finishing performance and carcass characteristics of beef heifers.
They said FFG, a byproduct of corn wet milling, has traditionally been used for corn oil production and contains 45% lipid and 12% crude protein (dry matter basis). They noted that FFG has been used successfully as a fat source in finishing diets containing dry-rolled corn.
Procedures
Montgomery et al. utilized 888 crossbred beef heifers with an initial weight of 837 lb. in the trial. The heifers were processed (including vaccination against respiratory and clostridial diseases and implanting) over eight days. Immediately following processing, heifers were randomly assigned to dirt-surfaced pens so that each pen contained between 14 and 23 heifers each, depending on pen size. Each pen served as the experimental unit, and pens were blocked by date of implanting.
They reported that the dietary treatments consisted of finishing diets formulated to provide no added fat (Control), 4% tallow or 10% or 15% FFG on a dry matter basis (10% FFG and 15% FFG, respectively) with or without 2,000 IU of additional vitamin E per heifer daily. Treatments were assigned randomly to pens within each block.
Heifers were maintained on the control diet until all heifers were processed, upon which time heifers were weighed and their respective dietary treatments were initiated, the researchers said. Diets were fed once daily and were offered for ad libitum consumption.
At the end of the 105-day finishing period, each pen of heifers was weighed and transported to a commercial slaughter facility. Hot carcass weights and the incidence of liver abscesses were recorded at time of slaughter, Montgomery et al. reported, and other carcass traits were measured following a 24-hour chill.
Results, discussion
The effects of fat addition and FFG on finishing performance and carcass characteristics are shown in Table 1. Fat addition decreased (P < 0.01) dry matter intake (DMI) and tended (P < 0.09) to improve, gain efficiency when compared to the control, Montgomery et al. reported, although marbling score and the percentage of carcasses grading U.S. Department of Agriculture Choice were decreased (P < 0.01) in response to supplemental fat. They said it was not known whether this was an effect of decreased feed intake or an effect of fat on marbling.
Tallow and 10%FFG yielded similar finishing performance and carcass characteristics, they said, which suggests that including FFG at 10% in finishing diets can effectively replace 4.2% tallow as a fat source.
According to the researchers, increasing FFG decreased DMI (linear, P < 0.01), daily gains (linear, P < 0.03), final bodyweight (linear, P < 0.02), hot carcass weight (linear, P < 0.02), as well as marbling score (linear, P < 0.01) and the number of carcasses grading USDA Choice (linear, P < 0.01).
Mongtomery et al. reported that gain efficiency was improved when 10% FFG was added to the diet, but this benefit was lost when it was increased to 15% of the diet (quadratic, P < 0.03). They said increasing FFG tended (linear, P < 0.06) to reduce the incidence of liver abscesses, which could be a result of decreased feed intake or possibly some antimicrobial property of the FFG that suppressed the growth of bacteria responsible for liver abscesses.
According to the group, vitamin E addition did not affect finishing performance but did marginally increase (P < 0.04) the number of carcasses grading USDA Select and decrease (P < 0.05) the number of carcasses grading USDA Standard (Table 2). They said this effect might have been due to the antioxidant properties of vitamin E.
So what?
According to Montgomery et al., this study suggests that FFG can serve as a supplemental fat source for finishing cattle and result in a performance response similar to that obtained from an equal amount of tallow.
High moisture tempering
Also at this year's Kansas State Cattlemen's Day, B.E. Depenbusch, J.S. Drouillard, R.K. Phebus, A.B. Broce, C.M. Gordon and J.J. Sindt presented their research on the role of high-moisture tempering in the spread of pathogens.
They said visual observations suggest that houseflies (Musca dornestica) have an affinity for tempered steam-flaked corn compared to nontempered steam-flaked corn. High-moisture tempering of whole shelled corn prior to flaking resulted in significantly higher moisture content (37%) of the flaked corn as compared to industry standards (20%).
Depenbusch et al. pointed out that recent research has shown that houseflies are a common carrier of pathogens such as salmonella and Escherichia coli O157:H7. They said, in light of these observations, one might conclude that tempering steam-flaked corn may attract more flies and pathogens resulting in higher number of foodborne pathogens shed by the cattle.
To test their theory, they tempered whole shelled corn by mixing corn with water in a stationary mixer periodically for 24 hours. The tempered corn was then flaked to a bulk density of 26 lb./bu., resulting in final moisture content of 37%. Nontempered whole shelled corn was also flaked to the same bulk density as the tempered steam-flaked corn samples. To determine initial bacterial counts, 250-g aliquots of tempered and nontempered corn were sampled directly from the steam faker following completion of the flaking process and immediately refrigerated.
Depenbusch et al. said additional samples of each corn treatment was acquired and left exposed to the environment and flies for the next 21 hours; samples were then aseptically mixed completely and thoroughly by hand. Random grab samples were used to acquire a 250-g aliquot, which was refrigerated prior to enumeration of microbial populations.
To determine whether tempering and exposure to flies had any effect on fecal shedding, Depenbusch et al. fed steers total mixed rations containing either tempered or nontempered steam-flaked corn and collected fecal samples on day 56 of the feeding period.
According to. these researchers, tempered steam-flaked corn samples had numerically higher generic E. coli coliforms, total coliforms and total plate counts. Non-E. coli coliforms, generic E. coli coliforms, total coliforms and total plate counts were all numerically higher for the tempered total mixed rations than for their nontempered counterparts, they reported.
Also, fly exposure significantly increased non-E. coli coliforms, genenc E. coli, total coliforms and total plate counts for the tempered and non-tempered steam-flaked corn samples (P < 0.05) but not the total mixed rations.
When fed to steers, Depenbusch et al. reported that those cattle that received nontempered rations actually shed more acid-resistant coliforms than cattle fed rations containing tempered steam-flaked corn. They said this was contrary to their hypothesis because cattle on the tempered rations had a greater intake of coliforms.
They suggested that competitive exclusion organisms and/or changes in the ruminal environment may be possible causes for the significant differences in the shedding of acid-resistant coliforrns.
TABLE 1. Finishing performance and carcass characteristics of heifers fed diets containing no added fat, 4% tallow or 10 and 15% FFG Treatment Item Control Tallow 10%FFG Number of heifers 220 222 224 Number of pens 12 12 12 Initial weight, lb. 826 826 822 Final weight, lb. (e) 1,130 1,130 1,131 DMI, lb. per day 19.5 18.6 18.7 Average daily gain, lb. 2.84 2.83 2.88 Gain:feed 0.146 0.152 0.154 Hot carcass weight, lb. 725 724 725 Dressing percentage (f) 64.3 64.3 64.3 Fat thickness, in. 0.54 0.56 0.57 Longissimus muscle area, sq. in. 13.6 13.5 13.5 Kidney, pelvic & heart fat, % 2.4 2.3 2.4 Liver abscesses, % 8.6 8.3 4.1 Yield grade 1, % 8 13 11 Yield grade 2, % 35 30 23 Yield grade 3, % 48 43 50 Yield grade 4, % 9 12 15 Yield grade 5, % 0 2 1 Marbling score (g) Sl95 Sl67 Sl78 USDA Prime, % 1 1 1 USDA Choice, % 42 30 35 USDA Select, % 54 60 56 USDA Standard, % 3 9 8 Dark cutters, % 0 0.3 0.6 Treatment Contrast Item 15%FFG SEM 1 (a) Number of heifers 222 -- -- Number of pens 12 -- -- Initial weight, lb. 822 6.6 0.76 Final weight, lb. (e) 1,106 6.3 0.25 DMI, lb. per day 18.0 0.17 <0.01 Average daily gain, lb. 2.65 0.053 0.34 Gain:feed 0.147 0.0026 0.09 Hot carcass weight, lb. 709 4.0 0.25 Dressing percentage (f) 63.9 0.16 0.63 Fat thickness, in. 0.52 0.017 0.77 Longissimus muscle area, sq. in. 13.4 0.15 0.71 Kidney, pelvic & heart fat, % 2.4 0.03 0.35 Liver abscesses, % 3.4 2.00 0.15 Yield grade 1, % 11 2.2 0.11 Yield grade 2, % 37 3.8 0.21 Yield grade 3, % 43 3.7 0.52 Yield grade 4, % 8 2.1 0.19 Yield grade 5, % 1 0.5 0.12 Marbling score (g) Sl62 5.3 <0.01 USDA Prime, % 0 0.4 0.19 USDA Choice, % 30 3.3 0.01 USDA Select, % 60 3.1 0.19 USDA Standard, % 10 1.8 0.03 Dark cutters, % 1.3 0.63 0.15 Contrast Item 2 (b) 3 (c) 4 (d) Number of heifers -- -- -- Number of pens -- -- -- Initial weight, lb. 0.70 0.67 0.91 Final weight, lb. (e) 0.88 0.02 0.04 DMI, lb. per day 0.76 <0.01 0.37 Average daily gain, lb. 0.54 0.03 0.02 Gain:feed 0.62 0.47 0.03 Hot carcass weight, lb. 0.88 0.02 0.04 Dressing percentage (f) 0.83 0.19 0.12 Fat thickness, in. 0.79 0.58 0.09 Longissimus muscle area, sq. in. 0.73 0.58 0.95 Kidney, pelvic & heart fat, % 0.06 0.33 0.13 Liver abscesses, % 0.15 0.06 0.70 Yield grade 1, % 0.58 0.23 0.60 Yield grade 2, % 0.17 0.79 0.01 Yield grade 3, % 0.14 0.49 0.25 Yield grade 4, % 0.42 0.83 0.02 Yield grade 5, % 0.24 0.41 0.54 Marbling score (g) 0.13 <0.01 0.40 USDA Prime, % 1.00 0.13 0.83 USDA Choice, % 0.29 0.01 0.55 USDA Select, % 0.43 0.25 0.88 USDA Standard, % 0.45 0.02 0.62 Dark cutters, % 0.68 0.07 0.83 (a) 1 = Control versus fat. (b) 2 = 10%FFG versus tallow. (c) 3 = Linear effect of FFG. (d) 4 = Quadratic effect of FFG. (e) Final weight = hot carcass weight divided by a common dressing percentage of 64.10%. (f) Calculated as hot carcass weight divided by (live weight x 0.96). (g) Sl = Slight. TABLE 2. Finishing performance and carcass characteristics of heifers fed diets containing no additional vitamin E or 2,000 IU of added vitamin E per heifer daily Treatment Item No Vitamin E Vitamin E SEM Number of heifers 448 440 -- Number of pens 24 24 -- Initial weight, lb. 824 824 4.8 Final weight, lb. 1,120 1,128 4.6 DMI, lb. per day 18.6 18.8 0.12 Average daily gain. lb. 2.76 2.84 0.039 Gain:feed 0.148 0.151 0.0019 Hot carcass weight, lb. 718 723 2.9 Dressing percentage 64.1 64.3 0.12 Fat thickness, in. 0.55 0.55 0.012 Longissimus muscle area, sq. in. 13.4 13.6 0.11 Kidney, pelvic & heart fat, % 2.4 2.4 0.02 Liver abscesses, % 7.8 4.5 1.45 Yield grade 1, % 12 10 1.6 Yield grade 2, % 30 33 2.8 Yield grade 3, % 44 47 2.7 Yield grade 4, % 13 9 1.5 Yield grade 5, % 1 1 0.4 Marbling score SI78 SI73 3.8 USDA Prime, % 1 0 0.3 USDA Choice, % 36 33 2.4 USDA Select, % 54 61 2.3 USDA Standard, % 9 6 1.3 Dark cutters, % 0.2 0.8 0.45 Item P-value Number of heifers -- Numberof pens -- Initial weight, lb. 0.98 Final weight, lb. 0.18 DMI, lb. per day 0.42 Average daily gain. lb. 0.12 Gain:feed 0.18 Hot carcass weight, lb. 0.18 Dressing percentage 0.43 Fat thickness, in. 0.91 Longissimus muscle area, sq. in. 0.41 Kidney, pelvic & heart fat, % 0.37 Liver abscesses, % 0.10 Yield grade 1, % 0.39 Yield grade 2, % 0.56 Yield grade 3, % 0.40 Yield grade 4, % 0.09 Yield grade 5, % 0.72 Marbling score 0.36 USDA Prime, % 0.32 USDA Choice, % 0.31 USDA Select, % 0.04 USDA Standard, % 0.05 Dark cutters, % 0.33
