HISTORY OF FEED PROCESSING John K. Matsushima Colorado State University Fort Collins, CO [email protected] INTRODUCTION Since cattle have the ability to masticate and regurgitate the feed(s) which they consume we would assume that it was not necessary to process (mechanically or by other means) the feed for them. In the early days, conditions were different when cattle survived by grazing on pasture or were fed harvested forages and fed a minimum quantity of grain. As time changed to increase the performance of animals it became necessary to increase the energy level in the diet by feeding a larger quantity of concentrates. Various grains became available. The cereal grains were found to possess varying characteristics such as shape, size, texture, etc. The

digestibility and palatability of these grains in their natural condition were found to be different to some degree. Through technology the development and introduction of processed cereal grains (as well as roughages) brought about the increase in animal performance and efficiency of meat and milk production. CHRONOLOGY (HISTORICAL EVENTS RELATED TO FEED PROCESSING) Although there have been numerous events that have transpired through the years in connection with feeding cattle, especially with high concentrate feeds, a few of these events are listed to tie in with history of feed processing. These events are listed in chronological order:

Chronology: Historical events related to feed processing 1800 Heavy grain feeding to beef cattle started in Ohio. 1840 Corn sheller and hammer mill were invented. 1852 Land-grant colleges endowed under Morrill Act. 1885 Commercial feed manufacturing industry began in Chicago. 1898 First publication of “Feeds and Feeding” by W.A. Henry. 1908 American Society of Animal Science adopted (formerly American Society of Animal Nutrition and American Society of Animal Production). 1920 Hybrid seed corn was produced and sold on limited basis. 1939 The rumen fistula was introduced for digestion studies (by Michigan State University researchers, C.F. Huffman and associates). 1942 Commercial cattle feeding began to emerge. 1962 Flaked corn introduced to large feedlots. 1963 The Net Energy system was designed by Lofgreen and Garrett for the beef cattle industry. WHY PROCESS FEEDS? There are several cereal grains that are available for livestock feeding. The production and harvesting rates as well as the prices of these grains usually varies with the geographical and climatic conditions. Livestock feeds (cereal grains) in harvested condition differ in many characteristics and therefore may be justifiable for processing prior to cattle feeding. These characteristic differences are noted in Table 1. The nutrient content of the grain may also be a contributing factor.

Table 1. Why process feeds? Livestock feeds (grains) in harvested condition differ in: 1. Size 2. Texture 3. Shape 4. Maturity 5. Moisture (length of storage) 6. Palatability ??? GRAIN PROCESSING METHODS Prior to the introduction of hybrid corn around 1920, flint and dent corn were fed to fattening cattle.

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This type of corn was hard and flinty. Hence, the practice of soaking the kernels emerged. An interesting trial in Kansas compared the performance of steers fed dry whole corn or whole soaked corn. Pigs followed the steers in each pen and the performance of pigs was also compared. The results provided the following thumb rule: “Ten pigs per ten steers.” There was another interesting observation in scanning through the early history of feed processing. Although Indian corn was not commonly used for livestock feed this type of corn became a useful tool for “rate of passage” study. Again, the Kansas researchers fed two pens of steers – one pen was fed “white” colored whole corn and the second pen was fed “red” colored whole corn. The “test” Table 2. Grain processing methods Dry Process Method Year Started1 Grinding 1840 Crimping 1930 Pelleting 1957 Extruding 1966 Popping 1966 Micronizing 1970 Roasting 1975

was to determine the “time” it took the kernels to pass through the digestive tract by counting the undigested kernels in the droppings every hour after feeding. White kernels were found to be easier to count and more consistent in the results. There are probably more than a dozen different methods of processing grains for cattle, particularly feedlot cattle. Many of these processing methods were investigated between 1950 and 1975. During this period, there were more than 200 research trials that were published. Among the various methods of processing grains it appears appropriate to classify them into two categories – Dry or Wet process. The processing methods with the beginning date of each method are shown in Table 2.

Wet Process Method Soaking2 Cooking, boiling2 Steam rolling (barley) Steam flaking (corn) High moisture-ensile Pressure cooker-roll Reconstitute3 (milo) Exploding (milo)

Year Started1 ???? ???? 1930 1950 1958 1966 1968 1972

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Approximate dates. These methods did not alter physical characteristics. Used for hard, dry grains. 3 Add hot water (160 °F), 20-30% moisture, cure 21 days in air tight silo, and roll. 2

THE BEGINNING OF COMMERCIAL CATTLE FEEDING When commercial cattle feeding began to emerge in the mid to late 1940s, the race for the title of “King of the cattle feedlot industry” started. The three contenders were: 1. Warren H. Monfort, Greeley, Colorado 2. Louis Dinklage, Wisner, Nebraska 3. Earle Brookover, Garden City, Kansas The three feeders met periodically, usually in West Point or Omaha, Neb., to discuss various means of improving their feeding operation. They invited John Matsushima from the University of Nebraska quite frequently. All three operators kept accurate records and agreed that the feed cost was the most expensive part of their business –

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approximately 75 to 80 percent. What can be done to reduce this feed cost? At one meeting in Omaha on a cold winter day when the temperature was several degrees below zero the three feeders and Matsushima were having breakfast. Instead of having the regular menu of bacon and eggs the four orders were either oat meal or corn flakes with “hot milk.” A bright idea flashed Matsushima’s brain -- “Why not feed corn flakes to the cattle in the feedlot?” The idea might have been good but the big question was “how will the corn be processed and who will do it?” At another meeting in Omaha, in the late 1950s, it was decided to approach a large feed manufacturing plant, John Nixon & Co. to design equipment to make corn flakes for a feedlot operation. Russ Kendall, the

mill operator and salesman for Nixon & Co. offered to assist. Before the plans went too far along Matsushima was lured away from Nebraska to Colorado by Warren Monfort. Louis Dinklage’s offer of a new

Cadillac to Matsushima to remain at Nebraska went for naught and the corn flake idea went to Colorado in 1961. The results from the first two feeding trials at Colorado convinced Warren and Kenny (son of Warren) to switch from ground corn to flake corn. In 1964, they installed 16 new flaking machines.

Table 3. Early corn flaking process, Colorado State Univesrity, 1962 1. No. 2 grade, 12% moisture corn used. 2. Gravity flow of whole corn into 15 in. x 34 in. x 6 ft. steam chamber. 3. Five steam jets located in chamber. 4. Duration of steam treatment – 11 to 12 minutes. 5. Temperature in steam chamber – approx. 200oF. 6. Two corrugated steel rollers at bottom of steam chamber.* 7. Setting of two rollers – produce 1/32 inch thick flaked corn. 8. Moisture content of flaked corn leaving rollers – 20%. 9. Denver Roll; Roskamp Mfg. and Ross Machine & Mill Supply.* *1962-1964.

PROTOTYPE DEVELOPMENT OF FLAKING MACHINE In order to prepare “corn flakes,” starting with whole dry corn, it was necessary to have two pieces of equipment – one to add moisture to the dry grain and the other to flatten the kernels. To add moisture to the grain, steam is much faster than using ordinary cold water. To flatten the kernel that has been moistened, appropriate roller machine is necessary to make flakes of proper thickness. The production rate is very important and therefore the design of the moisture adding compartment must coincide with the capacity to which the roller equipment can handle. In order to prepare the desired “corn flakes” for cattle feeding it took nearly two years to develop prototype flaking equipment. The assistance of three roller machine companies was involved. The most difficult portion of developing the prototype was the moisture addition (steam chamber) – the location and number of steam jets and the shape plus the dimensions (width, depth and length). Brief description and results in the prototype development of the steamed corn flakes are noted in Table 3.

EARLY FEEDING TRIAL (COLORADO) While the prototype flaking equipment was undergoing several changes at Colorado State University a cooperative feeding trial was conducted with a small commercial feedlot. The results from this test are shown in Table 4. As the commercial feedlot test was being completed another similar feeding trial was started at the Colorado State University research center. The results from the feeding trial are shown in Table 5. DENSITY CHARACTERISTICS OF FLAKED GRAINS Concurrently with the feeding trials various laboratory tests were conducted. One of the tests included the density (weight per volume) comparisons between flaked corn and cracked corn (Table 6). The milo comparisons are data from Oklahoma. Theurer et al (1999) indicated “…decreasing flake density from 437 to 283g/l (34 to 22 lb/bu) of steam processed corn or sorghum increased the proportion of starch digested in the rumen and digestive tract, resulting in less dietary starch digested in the small intestine. Decreasing flake density increased N digestibility when fed sorghum grain but not when they were fed corn.”

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Table 4. Flaked corn vs. cracked corn; 1962. First cooperative field trial. Colorado* Treatment Dry, Cracked Corn Steam Flaked Corn No. cattle 49 52 Initial weight, lbs 784.60 805.60 Final weight, lbs 1102.90 1140.80 Total gain, lbs 318.30 335.20 Avg. daily gain, lbs 2.51 2.64 Feed intake/day/head 20.28 19.77 Grain/lb of gain 8.08 7.50 Grain intake as percent of body wt, % 2.15 2.04 Roughage (dry basis) intake as percent of body wt, % 0.60 0.57 Dressing percent 64 63.74 *CSU in cooperation with Red Bird Feed & Grain Co., Eaton and Henry Schneider and Henry Ruff (commercial feeders), Ault, Colorado.

Table 5. Flaked corn vs. cracked corn vs. cooked-cracked corn* Regular Cracked Treatment Corn1 Initial weight, lbs 517 Final weight, lbs 920 Avg. daily gain, lbs 2.63 Avg. daily ration, lbs 21.20 Feed required/cwt gain (air dry), lbs 803 Dressing percent 61.70 Carcass grade4 17.30

Cooked, Cracked Corn2 515 896 2.49 21.80 877 62.90 17.70

Cooked, Flaked Grain3 516 904 2.54 19.60 772 62.90 16.90

* 1963. Colorado. 1 70% corn and 30% barley mix. 2 70% corn and 30% barley mix; cooked 12 minutes at 200°F. 3 70% corn and 30% barley mix; cooked 12 minutes at 200°F and rolled. 4 Ch+ = 18; Cho = 17.

Table 6. Change in weight per volume by processing Corna Wt/bu, lbsc Whole dry corn 56.5 Regular cracked corn 50.6 Steam flaked 24.2

Milob Whole dry milo Coarsely ground Steam flaked

Wt/bu, lbsc 59.1 49.7 23.3

a

Colorado State University. Oklahoma State University. c Air dry basis. b

Swingle et al (1999) reported that “Steam flaking of sorghum grain improves feeding value by 12-15 % principally by improving digestibility of starch in the rumen and total tract. Optimal flake density for steam flake sorghum appears to be 360 g/l (28 lb /bu).” Daily feed intake, daily gain, feed efficiency and carcass grades between the two comparisons

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were quite similar. (Hence, small feedlot operations can use flaked corn that was processed several days before feeding). Zinn and Barrajas (1997) reported “Retrogradation or loss of starch solubility was not enhanced by air drying corn after steam flaking. The characteristics of digestion and hence the feeding value of steam flaked corn are not altered by air drying before feeding.”

Table 7. Findings from early trials* 1. Flaked corn was lower in density vs. cracked corn: 27 lbs/bu (flaked) vs 38 lbs/bu (cracked) at 13% moisture. (Approximately 30% lighter.) 2. When fed in feedlot rations, flaked corn ration resulted in lower feed intake but daily gains were similar to cattle fed cracked corn. (a) Hence, feed efficiency was increased 8 – 10%. (b) No difference in carcass grade. 3. Results were comparable when flaked corn was fed immediately after processing or air dried to around 15% moisture and then fed. *1962-1964. Colorado.

Table 8. Early questions on feed processing1 1. Which grain processing method improves "feed efficiency" in feedlot cattle? 2. What factors account for this increase in feed efficiency? a. Increase in density of processed grain? b. Change in surface area for easier access to rumen microorganisms? c. Change in starch (gelatinization)? (birefringence)? d. Increase in moisture absorption? e. Change in rate of passage through digestive tract? f. Shift in proportion of volatile fatty acids? g. All of the above? 1

Timeframe: 1960 – 1980.

Table 9. Water uptake of corn particles due to processing* Method of Process Dry roll (cracked) Flaked

Soaking Time Minutes 1 1

Water Uptake, grams/ 100 grams 43 90

Dry roll (cracked) Flaked

10 10

49 75

Dry roll (cracked) Flaked

30 30

60 153

*1966. Colorado.

EARLY QUESTIONS ON FEED PROCESSING In the early stages when the flaking process of grain, particularly corn, was getting under way (Table 7), there were many unanswered questions. These questions are listed in Table 8. EFFECT OF PROCESSING ON MOISTURE ABSORPTION Undoubtedly there are many factors that will determine the extent of moisture absorption in the processed grain. Table 9 shows the rapid rate of water absorption by flaked corn as compared to cracked corn.

Moisture absorption in whole dry corn in the steam chamber can be increased at a faster rate by the application of a tempering agent. EFECT OF THICKNESS OF FLAKES The flaking process introduced a number of questions when the method emerged. One of these was: “How ‘thick’ should the flakes be?” Results from the first feeding trial at Colorado (1967) indicated that “thin flakes” appeared to be superior to “thick” flakes. (Table 10). Average daily gain was 4.3% greater by the steers fed the thin flake and feed efficiency was 7.8% superior as compared to the steers fed the thick flake.

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Table 10. Thickness of flaked corn* Treatment Initial weight, lbs Final weight, lbs Avg. daily gain, lbs Avg. daily corn consumption, lbs1 Avg. daily feed consumption1 Feed consumed/ lb gain1 Dressing percent, % Carcass grade: % Choice % Good

Thin 1/32 in 485 946 2.82 (12.41)

Thick 1/12 in 483 923 2.70 (12.66)

Fine Ground 1/4 in 490 922 2.65 (12.83)

6.14 64.21 93 7

6.66 63.71 92 8

6.88 63.25 92 8

*1967. Colorado Expt. Station. 1 Air dry basis.

Osman et al (1970) indicated “…degree of increase in starch digestion in barley and sorghum grain appears to be linearly related to thickness of flakes, thinner the flakes, the better the grain is utilized.” Zinn (1993) found that “steam processing in addition to rolling will further increase the net energy for maintenance value of barley by 2.8 to 7.0%, depending on the thinness of the flake. The comparative feeding values of dry-rolled, steam rolled course, and steam-rolled thin barley are 90, 92, and 96% of the value of steam-flaked corn.” Brown et al (2000) suggested that the optimum rate and efficiency of gain in feedlot steers occurred when corn was steam flaked to a bulk density between .36 and .26 kg/l (28 to 20 lb/bu). They also found that by increasing the degree of processing the enzymatic starch availability increased but the protein and ash content of the product decreased.

FLAKING AND STARCH GELATINIZATION A. Methods of measuring starch gelatinization: Since starch is the major component of cereal grains its contribution to the effectiveness of feed processing is quite obvious. The application of steam to the whole grain should be the initial step in the starch gelatinization process. Further gelatinization should occur as the moisturized grain passes through the rollers. Three methods were used at Colorado during the initial period when the flaking process emerged. The three methods used are shown in Table 11. The enzymatic hydrolysis, using beta amylase, was determined to be the most reliable method. During the mid 1960s the starch gelatinization data was compared to the feedlot trial data where the thickness of flake trial were being conducted. The early data comparisons showed that 50% starch gelatinization was optimal.

Table 11. Methods of starch gelatinization analysis (Colorado) 1. Early methods of gelatinization analysis a. Optical birefringence. b. Congo orange staining c. Enzymatic hydrolysis (beta amylase) (Early data showed this method to be most consistent.) 2. Early data showed 50% gelatinization to be optimal. B. Greatest gelatinization: at steaming vs. at rolling The degree of total starch gelatinization in the flaking process should be more important than comparing the degree of gelatinization during the steaming period or during the rolling period.

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Variations in the results will probably occur due to such conditions as: duration of steaming, type of roller, setting of the rollers, etc. The Kansas data (1966) indicates that the greatest gelatinization occurs during the rolling process (Table 12).

Table 12. Starch gelatinization of corn and milo1 Corn grain Corn after steaming Corn after flaking Flaked corn after airlift

% moisture 17.1 22.0 20.5 20.6

% gelatinization ---16 48 40

Milo grain Milo after steaming Milo after flaking Flaked milo after airlift

13.6 17.8 14.2 14.6

---12 40-702 47-692

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Phil Phar, Kansas (1966). % gelatinization variation, may be due to thickness of flakes.

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Table 13. Effect of processing on starch granules and digestibility* Method of Processing Cracked Flaked Flake-Cracked Starch granules: Per cent1 99 50-75 50-60 Digestibility: Dry matter, % Protein, % Acid detergent fiber, %

70.1 59.6 33.3

77.5 66.8 40.9

77.1 65.6 38.7

Cook-Cracked 98

72.4 62.5 40.2

*1966. Colorado. (Johnson). 1 Birefringence (starch granules examined with polarizing microscope).

EFFECT OF PROCESSING ON STARCH GRANULES Processing of feeds changes the physical characteristics of cereal grains, certain processing methods alter the starch granules. Johnson (1966) determined the differences in corn starch granules due to processing by the “birefringence” method. The starch granules were examined with a polarizing microscope. The results are shown in Table 13. Steam flaked corn showed considerable difference in starch granules as compared to dry cracked corn. Digestibility of protein and dry matter were slightly higher in steam flaked corn than in cracked corn. (Table 13). Microscopic determination of loss of birefringence is the most rapid, sensitive, reproducible method for the determination of gelatinization (Seib, 1971). Other methods such as bulk measurement, water absorbing capacity, diastatic enzyme conversion and artificial rumen digestion by measuring VFA production have been used to measure starch alteration due to feed processing (McLaren, 1968).

SITE AND EXTENT OF STARCH DIGESTION Even prior to the entrance of the processed grain into the digestives tract of the feedlot steer such feed as steam flaked corn or other steam flaked grains, the grain starch has already been prepared for microbial and enzymatic digestion through gelatinization. The extent or degree of gelatinization in the feed processing could then potentially affect the site and extent of starch digestion through the digestive tract. Diet and intake can affect ruminal fermentation and subsequent supply of starch to the small intestine (Richards et al. 2003). Stock et al. 1987) found that at high diet intakes, 400 to 2,300 g of starch can flow to the small intestine of beef steers. Owens et al. 1986) indicated small intestinal starch digestibility ranging from 47 to 88%. Starch digestion in the small intestine is theoretically more energetically efficient than ruminal fermentation (Harmon and McLeod, 2001).

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Table 14. Starch digestion in the small intestine (SI)* Source Diet McCullough 88% whole corn Laudert 80% cracked corn Remillard 60% cracked corn DeLay 90% flaked corn McCullough 88% flaked corn McLaren 80% extruded corn, 10% gelat. 80% extruded corn, 40% gelat. 80% extruded corn, 90% gelat.

Digestibility entering SI, % 88.3 59.1 68.1 69.5 86.2 15.0 9.8 6.1

*Colorado State University: Animal Science graduate students.

Starch digestion studies in the small intestine at Colorado indicated that the method of processing corn may vary from 6.1 to 86.2% with a high of 88.3% for whole corn. When the corn was processed through an extruder the digestibility of the starch was very low. The comparisons are shown in Table 14.

starch in whole shelled corn (Galyean et al., 1976). Although it would be rather rare to feed a combination of flaked corn and whole shelled corn in an ordinary feedlot ration the New Mexico researchers (Lee et al., 1982) found no difference in the percentage of fecal starch when flaked corn and whole shelled corn were fed in equal proportions. However, when flaked corn and whole shelled corn were fed separately, as expected, the percentage of fecal starch from the steers fed flaked corn was 39 to 59% lower than the steers fed the whole corn ration (Table 15).

FECAL STARCH AS A MEASURE OF FEED PROCESSING EFFECT Starch in steam flaked corn is digested to a greater extent in the rumen and entire digestive tract than

Table 15. Fecal starch and pH changes during feeding period of steam flaked corn and whole corn* Days on Feed 56 days 84 days 112 days 140 days Dietf pH %starche pH %starche pH %starche pH %starche 100W:0SFC 75W:25SFC 50W:50SFC 25W:75SFC 0W:100SFC

6.30a 6.35a 6.58b 6.74b 6.81b

14.0a 13.9a 12.2b 10.1c 5.7d

6.19ab 6.33a 6.43a 6.74c 6.42a

11.4b 14.8a 13.9a 7.1c 4.5d

6.49 6.40 6.33 6.39 6.36

21.2 a 14.9b 13.8b 9.4c 3.6d

6.06a 6.04a 6.09a 6.36b 6.20b

21.7a 8.7b 8.9b 5.6c 3.3d

*New Mexico (1982:Lee, Galyean and Lofgreen). a,b,c,d Means in the same column with different superscripts differ (P < 0.05). e dry matter basis. f W = whole corn; SFC = steam flaked corn.

Table 16. Fecal starch and pH of whole corn and cracked corn at 140 days feeding period* Whole-Crack Whole-Fine Mixture** Mixture** Whole Cracked Fine Ground Experiment 1 Fecal starch, % 16.8 17.0 20.4 16.3 20.3 Fecal pH 5.73 5.78 5.69 5.82 5.67 Experiment 2 Fecal starch, % Fecal pH

23.7

*Nebraska (Turgeon, Brink and Britton). **50-50 mixture.

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23.6

20.5 23.5 (data not given)

21.6

Results from Nebraska (Turgeon et al., 1983) found 16.8% and 23.8% fecal starch in two separate trials (Table 16). These figures compare closely to the 21.7% fecal starch found by the New Mexico researchers. EFFECT OF FEED PROCESSING ON VOLATILE FATTY ACIDS (VFA) The concentration and proportion of various volatile fatty acids can be obtained

from the rumen by a stomach tube or from fistulated animals. The results obtained from either method were found to be quite comparable (Table 17, 1966). Whole corn has a higher percentage (42%) of butyric acid but a lower percentage (33%) of propionic acid as compared to ground corn (Sharp et al., 1982) (see Table 18).

Table 17. Volatile fatty acids (VFA) in rumen fluids1 Flaked Corn Cracked Corn Sampling Method Stomach Tube Fistula Stomach Tube Fistula Molar percentage of total VFA Acetic 57.3 58.2 55.5 61.7 Propionic 26.4 27.0 29.6 25.1 Butyric 12.9 11.3 11.0 10.1 Valeric 3.5 3.5 3.9 3.1 A/P ratio

2.2

2.2

1.9

2.5

1

1966. Johnson (Colorado).

Table 18. Rumen volatile fatty acid concentrations in whole vs. ground corn (moles/100mol)* Whole Corn Ground Corn Acetic 45.5 39.3 a Propionic 31.2 46.9b Butyric 16.24 a 9.38 b Isobutyric 1.00 0.71 3-methyl butyric 0.80 a 0.48 b a Valeric 2.60 1.83 b a Caproic 1.10 0.69 b

SE 4.5 4.6 1.5 0.15 0.08 0.21 0.13

*Oklahoma (1982. Sharp, Johnson and Owens). a,b Means with different superscripts differ (P < 0.05).

EFFECT OF PROCESSING ON DIGESTIBILITY OF GRAINS If processing changes the density, particle size, surface area, starch characteristic of the grain as it enters the rumen its “condition” should be made

Table 19. Digestibility of flaked and cracked corn, %* Flaked Dry Matter 74.8 Protein 64.5 Ether Extract 85.1 Acid Detergent Fiber 33.6

favorable for the microflora and thereby increase the digestibility. A comparison of steam flaked corn with cracked corn in a Colorado trial (Johnson, 1966) showed an increase in dry matter, protein and ether extract digestibility as compared to cracked corn (Table 19).

Cracked 70.1 59.6 78.2 33.3

*1966. Colorado (Johnson).

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The general pattern as indicated by numerous trials shows that cattle fed steam flaked corn or steam flaked sorghum have higher digestibility of grain and correspondingly superior feed efficiency as compared to cattle fed dry cracked grain.

drying. Ensiling such corn would preserve the corn without deterioration. Purdue University (1958) reported the first successful feeding trial using highmoisture ear corn. The cattle on high moisture ear corn gained 9% more with 5% better feed efficiency as compared to the cattle fed regular dry ear corn.

EFFECT OF OTHER METHODS OF FEED PROCESSING During the span of approximately 40 years (1930 to 1970) there were nearly twelve different methods of feed processing that were explored. Besides the steam flaking process another method was investigated and has continued to be adapted to the feedlot industry.

Later, high-moisture shelled corn was ground and stored in glass-lined silos or in concrete silos. Commercial feedlots in the mid-west and other cattle feeding areas began to utilize this method of processed grain supply. Some feedlots using corn silage as their only roughage source did not use highmoisture corn in the feeding program because of reduced dry matter intake and daily gain.

A. High moisture grain processing As the cattle feeding industry started to mushroom in the mid-western section of the United States in the mid 1950s the small cattle feeders began to utilize their home-grown feeds. The harvested corn was usually too high in moisture (30%) and therefore difficult to store in the corn cribs without artificial

Data from Oklahoma (1988) showed that the cattle fed high-moisture corn gained more than the cattle fed steam-flaked corn with comparable feed efficiency. (Table 20).

Table 20. Feedlot performance of cattle fed processed grains1 Corn Dry Rolled Steam Flaked Daily gain, lbs 2.75 2.75 2 Feed intake, lbs 17.07 15.70 Feed efficiency, lbs2 6.21 5.71 Improvement: Total ration Grain only Grain in diet, %

+8.1% +10.9% 74

74

Whole Shelled 2.75 17.02 6.19

High Moisture 2.84 16.50 5.81

+0.3% +0.4% 78

+6.5% +8.1% 80

1

1988. Wagner (Oklahoma). 2 Dry matter basis.

Table 21. Feedlot performance of cattle fed processed grains1

Milo Daily gain, lbs Feed intake, lbs2 Feed efficiency, lbs2 Improvement: Total ration Grain only Grain in diet, % 1

1988. Wagner (Oklahoma). 2 Dry matter basis.

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Dry Rolled 2.56 16.79 6.56

74

Steam Flaked 2.76 16.06 5.82

+11.2% +15.1% 74

High Moisture Processed 2.76 15.7 5.68

+13.4% +17.2% 78

Popped, Exploded or Micronized 2.76 16.07 5.82

+11.2% +15.2% 74

B. Popped, exploded or micronized Oklahoma researchers (1988) found the cattle fed popped, exploded or micronized milo made similar gains with equal feed efficiency as the cattle fed steam-flaked milo. (See table 21).

were fed whole, coarse grind, fine grind, pellet, and ground pellets on free choice basis to determine the preference by calves. The calves preferred the whole oats of the 15 different choices while the calves offered the ground oat pellets ranked last.

GRAIN PREFERENCE BY CATTLE (CALVES) Prior to the use of “modern” processed grains (such as steam flaked) a rather unique experiment was conducted by Arkansas researchers in 1959 (Table 22). Three different cereal grains (corn, milo and oats)

It would be interesting to see a comparison of corn, sorghum, barley and oats with the “modern” feed processing methods -- whole (control) vs. steamflake vs. high moisture vs. coarse grind in a finishing ration.

Table 22. Grain preference by cattle (calves)* Whole Coarse Grind lbs lbs Corn 139 145 Milo 171 131 Oats 186 176

Fine Grind lbs 140 61 98

Pellet lbs 93 144 88

Ground Pellets lbs 37 55 27

*1959. Arkansas (15@315 lb calves, 105 days). Lespedeza hay.

STEAM-FLAKED CORN VS. STEAM-FLAKED MILO The choice of using steam-flaked corn or steamflaked milo in a cattle finishing ration would undoubtedly depend upon the availability and cost of the unprocessed grain. Slight differences may occur in the fuel cost of processing the two grains since the steam application time to the milo grain is longer. The performance (daily gain and feed efficiency) of cattle and carcass quality are very similar (Table 23).

SUMMARY The choice of feed processing by different methods for the beef cattle feedlot industry appears to be steam-flaking. The favorable results from the chemical laboratory to the live animal experimental feeding trials in the literature survey of more than 200 published reports reveal this choice. This choice is substantiated by the wide use of the method in the current cattle feeding industry. There are a number of reasons why steam-flaking is the choice for processing corn and milo. A few of these reasons are noted in Table 24.

Table 23. Steam flaked corn vs. steam flaked milo* Steam Flaked Corn Avg. daily gain, kg 1.79 Daily feed, kg 9.77 Gain/feed 0.183 Dressing % 63.0 % choice grade 83

Steam Flaked Milo 1.79 9.68 0.184 63.8 83

*1992. Kansas State (Brandt et al.).

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Table 24. Summary: Why steam-flaking is the choice for feed processing Flaking appears to be the choice for processing corn and milo for feedlot rations in finishing cattle (flaking vs. cracked) 1. 8 to 12% superior feed efficiency (feed/gain). 2. 10 to 30% decrease in density (weight per bushel) on dm. basis. 3. 8 to 10% faster rate of passage through alimentary tract. 4. 3 to 6% increase in dry matter digestibility. 5. 35 to 50% increase in water uptake. 6. Optimum starch gelatinization is approximately 50%. 7. Slight alteration in proportion of volatile fatty acids. 8. Decrease in energy loss as methane gas. 9. No difference in carcass quality. 10. Flaked corn and flaked milo are nearly equal in feedlot rations. LITERATURE CITED Aimone, J. C., and D. G. Wagner. 1977. Micronized wheat. I. Influence of feedlot performance, digestibility, VFA and lactate levels in cattle. J. Anim. Sci. 44:1088. Armstrong, D. G. 1972. Developments in cereal processing – ruminants. USA, US. Feed Grains Council: Cereal processing digestion. April. pp. 9-37. Beeson, W. M., T. W. Perry, and R. E. Honnold. 1956. High-moisture ground ear corn vs. regular ground ear corn. Purdue Univ. Expt. Sta., Mimeo A.H. 169. Brandt, R. T., Jr., G. L. Kuhl, R. E. Campbell, C. L. Kastner, and S. L. Stroda. 1992. Effects of steam-flaked sorghum grain or corn and supplemental fat on feedlot performance, carcass traits, longissimus composition, and sensory properties of steers. J. Anim. Sci. 70:3293. Brasher, T. 1972. Whole vs. flaked corn for beef cattle. Ph. D. thesis. Colorado State University. Animal Science Department. Brown, M. S., C. R. Krehbiel, G. C. Durr, M. L. Galyean, D. M. Hallford, and D. A. Walker. 2000. Effect of degree of corn processing on urinary nitrogen composition, serum metabolite and insulin profiles, and performance by finishing steers. J. Anim. Sci. 78:2464. Buchanan-Smith, J. G., R. Totusek, and A. D. Tillman. 1968. Effect of methods of processing on digestibility and utilization of grain sorghum by cattle and sheep. J. Anim. Sci. 27:525. Burroughs, W., P. Gerlaugh, E. A. Silver, and A. F. Schalk. 1946. Methods for identifying feeds and measuring their rate of passage through the rumen of cattle. J. Anim. Sci. 4:272. Butterbaugh, J., and J. K. Matsushima. 1974. The feeding value of combinations of processed corn in feedlot rations. Beef Nutrition Research. Colorado Experiment Station. General Series 934. pp. 27-29. Byers, F. M. 1974. The importance of associative effects of feeds on corn silage and corn grain net energy values. Ph. D. thesis. Colorado State University. Animal Science Department. Byers, F. M., D. E. Johnson, and J. K. Matsushima. 1976. Associative effects between corn and corn silage on energy partitioning by steers. In: M. Vermorel (Ed.) Energy Metabolism of Farm Animals. pp. 253-256. G de Bussac, Clermont- Ferend, France. Cabezas, M. T. 1964. The effect of physical form on nutritive value of ruminant diets. Ph.D. thesis. University of Florida, Gainesville. Chapman, R. J. 1969. Digestibility of whole, flaked, and extruded corn. M.S. degree thesis. Colorado State University. Animal Science Department. Chapman, R. J., and J. K. Matsushima. 1970. Digestibility and feedlot performance of cattle fed extruded, flaked and whole shelled corn. Research Highlights of the Animal Science Dept., Colo. Expt. Sta. Gen. Series 894. pp. 4-6. Church, D. C. 1969. Passage of digesta through the gastrointestinal tract. In: Digestive Physiology and Nutrition of Ruminants. Vol. 1. Oregon State University, Corvalis. Cole, N. A., R. R. Johnson, F. N. Owens, and D. Williams. 1976b. Influence of roughage level and corn processing method on microbial protein synthesis by beef steers. J. Anim. Sci. 43:497. Cooper, R. J., C. T. Milton, T. J. Klopfenstein, T. L. Scott, C. B. Wilson, and R. A. Mass. Effect of corn processing on starch digestion and bacterial crude protein flow in finishing cattle. J. Anim. Sci. 80:797.

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Corona, L., F. N. Owens, and R. A. Zinn. 2006. Impact of corn vitreousness and processing on site and extent of digestion by feedlot cattle. J. Anim. Sci., 84:3020. DeLay, R. L. 1972. Bovine duodenal amylase activity. Ph. D. thesis. Colorado State University. Animal Science Department. Dowe, T. W., J. K. Matsushima, and V. H. Arthaud. 1955. The effects of the corn-hay ratio on the digestibility of the different nutrients by cattle. J. Anim. Sci. 14:340. Dowe, T. W., V. H. Arthaud, and J. K. Matsushima. 1955. Ratio of concentrates to alfalfa hay in fattening rations for beef cattle. Nebr. Expt. Sta. Bul. 431. Dwyer, James F. 1972. Utilization of high moisture corn. M.S. degree thesis. Colorado State University. Animal Science Department. Ehle, F. R., and M. D. Stern. 1986. Influence of particle size and density on particulate passage through alimentary tract of Holstein heifers. J. Dairy Sci. 69:564. Etchebarne, Michel A. 1978. Comparative buffer effect on bovine rumen fermentation. M.S. degree thesis. Colorado State University. Animal Science Department. Ewing, D. L., D. E. Johnson, and W. V. Rumpler. 1986. Corn particle passage and size reduction in the rumen of beef steers. J. Anim. Sci. 63:1509. Franks, L. G., J. R. Newsom, R. E. Renbarger, and R. Totusek. 1972. Relationship of rumen volatile fatty acids to type of grain, sorghum grain processing method and feedlot performance. J. Anim. Sci. 35:404. Frederick, H. M., B. Theurer, and W. H. Hale. 1973. Effect of moisture, pressure, temperature on enzymatic starch degradation of barley and sorghum grain. J. Dairy Sci. 56:595. French, Dexter. 1973. Chemical and physical properties of starch. J. Anim. Sci. 37:1048. Galyean, M. L., D. G. Wagner, and F. N. Owens. 1976. Site and extent of starch digestion in steers fed processed corn rations. J. Anim. Sci. 43:1088. Galyean, M. L., D. G. Wagner, an F. N. Owens. 1979a. Level of feed intake and site and extent of digestion of high concentrate diets by steers. J. Anim. Sci. 49:199. Galyean, M. L., D. G. Wagner, and F. N. Owens. 1979b. Corn particle size and site and extent of digestion by steers. J. Anim. Sci. 49:204. Galyean, M. L., D. G. Wagner, and F. N. Owens. 1981. Dry matter and starch disappearance of corn and sorghum as influenced by particle size and processing. J. Dairy Sci. 64:1804. Garrett, W. N. 1965. Comparative feeding value of steam rolled or ground barley and milo for feedlot cattle. J. Anim. Sci. 24:726. Hale. W. H., L. Cuitun, J. Saba, B. Taylor, and B. Theurer. 1966. Effect of steam processing and flaking milo and barley on performance and digestion by steers. J. Anim. Sci. 25:392. Hale, W. H. 1973. Influence of processing on the utilization of grains (starch) by ruminants. J. Anim. Sci. 37:1075. Harbers, L. H. 1975. Starch granule structural changes and amylolytic patterns in processed sorghum grain. J. Anim. Sci. 41:1496. Harmon, D. L., and K. R. McLeod. 2001. Glucose uptake and regulation by intestinal tissues: implications and whole-body energetics. J. Anim. Sci. 79:E59. Henry, W. A. 1898. Grinding grain. Feeds and Feeding. (A hand-book for the student and stockmen). Published by the author (1st. Edition). pp. 243-244. Henry, W. A., and F. B. Morrison. 1917. Feeding corn in various forms. Feeds and Feeding. Morrison Publishing Co. (17th Edition). pp. 452-453. Hibberd, C. A., D. G. Wagner, R. L. Schemm, E. D. Mitchell, D. E. Weibel, and R. L. Hintz. 1982. Digestibility characteristics of isolated starch from sorghum and corn grain. J. Anim. Sci. 55:1. Hill, T. M., S. P. Schmidt, E. E. Thomas, R. R. Russell, D. F. Wolfe, and W. C. Ellis. Effect of differently processed grain sorghum on passage rates of different feed residues. J. Anim. Sci. 67 (Suppl. 1) :26 (Abst.). Hinds, F. C., R. W. Kleis, W. W. Albert, and A. L. Neumann. 1956. Comparison of three methods of grinding corn for beef steers. J. Anim. Sci. 15:1237. (Abstract). Hinman, D. D., and R. R. Johnson. 1974a. Influence of processing methods on digestion of sorghum starch in high concentrate beef cattle rations. J. Anim. Sci. 39:417. Hironaka, R. K., K. A. Beauchemin, and T. J. Lysyk. 1992. The effect of thickness of steam-rolled barley on its utilization by beef cattle. Can. J. Anim. Sci. 72:279. Holmes, J. H. G., M. J. Drennan, and W. N. Garrett. 1970. Digestion of steam-processed milo by ruminants. J. Anim. Sci. 31:409. Hristov, A. N., S. Ahvenjharvi, T. A. McAllister, and P. Huhtanen. 2003. Composition and digestive tract retention time of ruminal particles with functional specific gravity greater or less than 1.02. J. Anim. Sci. 81:2639.

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Huck, G. L., K. K. Kreikemeier, G. L. Kuhl, T. P. Eck, and K. K. Bolsen. 1998. Effects of feeding combinations of steamflaked grain sorghum and steam-flaked high-moisture, or dry-rolled corn on growth performance and carcass characteristics in feedlot cattle. J. Anim. Sci. 76:2984. Johnson, D. E. 1966. Utilization of flaked corn by steers. Ph. D. thesis. Colorado State University. Animal Science Department. Karr, M. R., C. O. Little, and G. E. Mitchell. 1966. Starch disappearance from different segments of the digestive tract of steers. J. Anim. Sci. 25:652. Kick, C. H., Paul Gerlaugh, and A. F. Schalk. 1937. Some factors affecting the length of time whole corn kernels are retained in the rumen of steers. Amer. Soc. Anim. Prod. Proc. of 32nd. Annual Meeting. p. 95. Laudert, S. B. 1982. Limestone effects on ruminant gastrointestinal tract, pH, site of digestion and feedlot performance. Ph. D. thesis. Colorado State University. Animal Science Department. Leonard, E. S., K. R. Pond, R. W. Harvey, and R. G. Crickenberger. 1989. Effects of corn grinding and time of corn feeding on growth, starch utilization and digesta passage characteristics of growing steers fed hay based diets. J. Anim. Sci. 67:1603. Lee, R. W., M. L. Galyean, and G. P. Lofgreen. 1982. Effects of mixing whole shelled corn and steam flaked corn in finishing diets on feedlot performance and site and extent of digestion in beef steers. J. Anim. Sci. 55:475. Liang, Y. T., J. L. Morrill, F. R. Anstaett, A. D. Dayton, and H. B. Pfost. 1970. Effect of pressure, moisture and cooking time on susceptibility of corn and sorghum grain starch to enzymatic attack. J. Dairy Sci. 53:No. 3, 336. Little, G. O., G. E. Mitchell, Jr., and C. M. Reitnour. 1968. Postruminal digestion of corn starch in steers. J. Anim. Sci. 27:290. Lofgreen, G. P., H. Kiesling, and J. K. Elliott. 1980. Steam flaked, dry rolled and whole shelled corn in a conventional milled diet for finishing steers. J. Anim. Sci. Suppl. 1. 51:378. Lund, D. 1984. Influence of time, temperature, moisture, ingredients and processing conditions on starch gelatinization. CRC Crit. Rev. Food Sci. Nutr. 20:249. Mason, T. R. 1973. Innovations in grain processing. Feed Management. pp. 14-16. Matsushima, J. K., J. I. Sprague, and D. E. Johnson. 1964. Flaked or cracked grain – which is superior for beef cattle? Colorado Farm & Home Research. Colorado Expt. Sta. Vol. 14, No. 4. pp. 6-8. Matsushima, J. K. 1969. Selection, preservation, processing of feeds; ration formulation for the production of slaughter beef cattle. Societa Italiana per Progresso della Zootechica – Milano, Atti Del IV. International Zootechnic Symposium. Milano, Italy. pp. 205-210. Matsushima, J. K., R. J. McLaren, C. P. McCann, and G. E. Kellog. 1969. Processing grains for feedlot cattle: extrusion, flaking, reconstituted and high moisture ensiled. Beef Nutrition Research. Colo. Expt. Stat. and Animal Science Department. pp. 8-10. Matsushima, J. K., and W. D. Farr. 1995. A Journey Back – A History of Cattle Feeding in Colorado and the United States. pp. 132-134. Matsushima, J. K. 2003. A Century of Progress (1903-2003). History of the Animal Science Department, Colorado State University. pp. 41-74. McCullough, M. W. 1973. Effects of corn processing and roughage level on steer performance and gastroenteric starch disappearance. Ph. D. thesis. Colorado State University. Animal Science Department. McLaren, R. J. 1971. Starch alteration in beef rations. Ph. D. thesis. Colorado State University. Animal Science Department. McNeill, J. W. 1971. Ruminal and postruminal carbohydrate utilization in steers fed processed sorghum grain. J. Anim. Sci. 33:1371. McNeill, J. W., G. D. Potter, J. K. Riggs, and L. W. Rooney. 1975. Chemical and physical properties of processed sorghum grain carbohydrates. J. Anim. Sci., 40:335. Mendoza, G. D., R. A. Britton, and R. A. Stock. 1993. Influence of ruminal protozoa on site and extent of starch digestion and ruminal fermentation. J. Anim. Sci., 71:1572. Montgomery, R. L. 1967. Flaked corn-corn meal for beef cattle. M.S. degree thesis. Colorado State University. Animal Science Department. Morrison, F. B. 1954. Preparation of feeds. Feeds and Feeding. Morrison Publishing Co. (22nd Edition). pp. 804-805. Ørskov, E. R. 1976. The effect of processing on digestion and utilization of cereals by ruminants. Proc. Nutr. Soc. 35:245. Ørskov, E. R. 1986. Starch digestion and utilization in ruminants. J. Anim. Sci. 63:1624. Osman, H. F., B. Theurer, W. H. Hale, and S. M. Mehen. 1970. Influence of grain processing on in vitro enzymatic starch digestion of barley and sorghum grain. J. Nutr., 100:1133. Owens, F. N., R. A. Zinn, and Y. K. Kim. 1986. Limits to starch digestion in the ruminant small intestine. J. Anim. Sci. 63:1634.

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Owens, F. N., D. S. Secrist, W. J. Hill, and D. R. Gill. 1997. The effect of grain source and grain processing on performance of feedlot cattle: A review. J. Anim. Sci. 75:868. Philippeau, C., C. Martin, and B. Michael-Doreau. 1999. Influence of grain source on ruminal characteristics and rate, site, and extent of digestion in beef steers. J. Anim. Sci. 77:1587. Poncet, C. 1991. The outflow of particles from the reticulo-rumen. In: Rumen microbial metabolism and nutrient digestion. J. P. Jouany, ed. INRA Publishing. Paris. Ramirez, R. F., H. E. Kiesling, M. L. Galyean, G. P. Lofgreen, and J. K. Elliott. 1985. Influence of steam-flaked, steamedwhole or whole shelled corn on performance and digestion in beef steers. J. Anim. Sci. 61:1. Ray, M. L., and C. Drake. 1959. Effects of grain preparation on preferences shown by beef cattle. J. Anim. Sci. 18:1333. Remillard, R. L., and D. E. Johnson. 1984. Starch digestion in the bovine small intestine with and without buffer and amylase infusion. J. Anim. Sci 59 (Supplement 1):444. Richards, C. J., K. C. Swanson, S. J. Paton, D. L. Harmon, and G. B. Huntington. Pancreatic exocrine secretion in steers infused postruminally with casein and cornstarch. J. Anim. Sci. 81:1051. Riggs, J. K. 1958. Fifty years of progress in the nutrition of beef cattle: physical form of feeds. J. Anim. Sci. 17:984. Russell, J. R., A. W. Young, and N. A. Jorgenson. 1981. Effects of dietary corn starch intake on ruminal, small intestinal and large intestinal starch digestion in cattle. J. Anim. Sci. 52:1170. Salsbury, R. L., J. A. Hoefer, and R. W. Luecke. 1961. Effect of heating starch on its digestion by rumen microorganisms. J. Anim. Sci. 20:569. Seib, P. 1971. Starch gelatinization: chemical and physical effects. Feedstuffs. March 13. p. 44. Sharp, W. M., R. R. Johnson, and F. N. Owens. 1982. Ruminal VFA production with steers fed whole or ground corn grain. J. Anim. Sci. 55:1505. Shellenberger, P. R., and E. M. Kesler. 1961. Rate of passage of feeds through the digestive tract of Holstein cows. J. Anim. Sci. 20-416. Siegel, A. 1980. Evaluation of freshly harvested high moisture corn. M.S. degree thesis. Colorado State University. Animal Science Department. Sindt, J. J., J. S. Drouillard, E. C. Titgemeyer, S. P. Montgomery, R. R. Loe, B. E. Depenbusch, and P. H. Walz. 2006. Influence of steam-flaked corn moisture level and density on the site and extent of digestibility and feeding value for finishing cattle. J. Anim. Sci. 84:424. Stenquist, N. J. 1968. Digestibility of high moisture corn. Ph. D. thesis. Colorado State University. Animal Science Department. Stock, R. A., M. H. Sindt, R. M. Ceale IV, and R. A. Britton. 1991. High-moisture corn utilization in finishing cattle. J. Anim. Sci. 69:1645. Swingle, R. S., T. P. Eck, C. B. Theurer, M. De la Llata, M. H. Poore, and J. A. Moore. Flake density of steam-processed sorghum grain alters performance and site of digestibility by growing-finishing steers. J. Anim. Sci. 77:1055. Theurer, B., J. Trei, and W. H. Hale. 1967. In vitro volatile fatty acid production as influenced by steam processing and flaking milo and barley. Proc. West. Sec. Amer. Soc. Anim. Sci. 18:189. Theurer, C. B. 1986. Grain processing effects on starch utilization by ruminants. J. Anim. Sci. 63:1649. Theurer, C. B., R. S. Swingle, R. C. Wanderly, R. M. Katnig, A. Urias, and G. Ghenniwa. 1999. Sorghum grain flake density and source of roughage in feedlot cattle diets. J. Anim. Sci. 77:1066. Thomas, E. E., G. W. Turnbull, and R. W. Russell. 1988. Effect of particle size and steam treatment of feedstuffs on rate and extent of digestion (in vitro and in situ). J. Anim. Sci. 66:243. Thomas, O. O., and L. L. Meyers. 1961. Steam or dry rolled barley in high concentrate rations for fattening beef steers. J. Anim. Sci. 20:953. (Abstract). Tonroy, B. R., and T. W. Perry. 1975. Effect of roasting corn at different temperatures on grain characteristics and in-vitro starch digestibility. J. Dairy Sci. 68:566. Turgeon, O. A., Jr., D. R. Brink, and R. A. Britton. 1983. Corn particle size mixtures, roughage level and starch utilization in finishing diets. J. Anim. Sci. 57:739. Wagner, D. G., W. Schneider, and R. Renbarger. 1970. Influence of steaming time on the nutritive value of steam flaked milo. Okla. Agric. Exp. Sta. Misc. Publi. 84:33. Waldo, D. R. 1973. Extent and partition of cereal grain starch digestion in ruminants. J. Anim. Sci. 37:1062. White, T. W., T. W. Perry, B. R. Tonroy, and V. L. Lechtenberg. 1973. Influence of processing on in vitro and in vivo digestibility of corn. J. Anim. Sci. 37:1414. Wolfe, G. D., Jr. 1975. Body composition changes in beef cattle due to grain processing. M.S. degree thesis. Colorado State University. Animal Science Department. Wray, M. I. 1982. Effect of dietary carbohydrate and protein processing on in-vivo and in-vitro nutrient utilization. Ph. D. thesis. Colorado State University. Animal Science Department.

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Zinn, R. A., and F. N. Owens. 1980. Expanding our concept of starch tract digestion in the ruminant. In: Proc. 41st. Minnesota Nutr. Conf. University of Minnesota, St. Paul. pp. 69-77. Zinn, R. A. 1990a. Influence of flake density on the comparative feeding value of steam-flaked corn for feedlot cattle. J. Anim. Sci. 68:767. Zinn, R. A. 1990b. Influence of steaming time on site of digestion of flaked corn in steers. J. Anim. Sci. 68:776. Zinn, R. A. 1991. Comparative feeding value of steam-flaked corn and sorghum in finishing diets supplemented with or without sodium bicarbonate. J. Anim. Sci. 69:905. Zinn, R. A. 1993. Influence of processing on the comparative feeding value of barley for feedlot cattle. J. Anim. Sci. 71:3. Zinn, R. A. 1994. Influence of processing on the feeding value of oats for feedlot cattle. J. Anim. Sci. 71:2303. Zinn, R. A., and R. Barrajas. 1997. Comparative ruminal and total tract digestion of a finishing diet containing fresh vs airdry steam-flaked corn. J. Anim. Sci. 75:1704. Zinn, R. A., F. N. Owens, and R.A. Ware. 2002. Flaking corn: processing mechanics, quality standards, and impacts on energy availability and performance of feedlot cattle. J. Anim. Sci. 80:1145.

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