Anyone who produces cattle is aware that the options available for feeding and supplementing cattle can seem virtually unlimited. Many producers, however, commonly take for granted that everything we feed to cattle has to revolve around some combination of corn or milo, soybean meal or cottonseed meal. Over the next few issues we'll take an extended view of a number of the other commodities or feed ingredients that can be used alone or in combination as a source of nutrients for cattle.
Let's take a comparative look at a number of the ingredients common to cattle feeding. Table 1. illustrates some average protein and energy values of several feedstuffs.
One very common feed ingredient commonly used in feeding and supplementation is soybean hulls. Soyhulls are by-products of soybean processing and are an excellent source of digestible fiber and energy. Let's consider some information concerning soyhulls.
Two areas of considerable potential for using the high-fiber by-product feeds, such as soybean hulls, corn gluten feed, and wheat midds, are to replace hay during the winter for cows or enhance performance of backgrounded calves being fed forage-based diets. Considerable research has been reported demonstrating the high nutritive value of these feedstuffs to ruminants.
As mentioned, soybean hulls are a by-product of soybean processing for oil and meal production. Typically soybean hulls do not require special processing to feed. However, soybean hulls have urease
(an enzyme) activity which can be a problem in rations containing urea. Heat treatment destroys the urease activity. Soybean hulls which have been heat treated are referred to as soybean mill run, soybean flakes or soybran flakes.
AS A SOURCE OF FIBER: A number of researchers have conducted winter feeding experiments to determine the feasibility of using soybean hulls instead of hay as a winter feed. In one study, cows were grazed on stockpiled tall fescue and fed hay (tall fescue) ad-libitum when pasture became limiting. Feeding 4 pounds of soybean hulls from December through March saved approximately 625 pounds of hay per cow and less body weight loss (13 pounds) than feeding hay only (86 pounds). Estimating hay costs at $80 per ton and soybean hull costs (delivered) at $80 per ton, this resulted in a $6.00 per head savings over the feeding period.
AS A SOURCE OF ENERGY: Other work has been done using soybean hulls as a replacement for corn in steers maintained on forage-based diets. In one study steers were maintained on tall fescue. One set of steers were fed 4 pounds of soybean hulls and another set was fed 4 pounds of corn while on grass. A third set of steers received no supplement. The steers gained similarly on soybean hulls and corn (2 pounds per day gain), with both being greater than the gain of steers that were not supplemented (1.5 pounds per day gain). Soybean hulls have been found to be equal to corn for rate and efficiency of gain when fed as a creep supplement to steer calves. However there are limits to soybean hulls being equal to corn. Feedlot steers fed corn or soybean hulls as the primary dietary energy source, had similar intakes and daily gains but the soybean hull diet had lower feed conversions than the corn diet. Soybean hulls appear to be more beneficial as a supplement for growing animals that are grazing or fed hay, compared with high energy, feedlot diets. Differences in feed costs would determine which is the most economical choice.
FEEDING: Soyhulls are fed in whole, ground, or pelleted forms. One disadvantage of whole or ground soyhulls is that they are light weight and have a tendency to blow in commodity barns or when loading feed in windy conditions.
Corn Gluten Feed
Corn gluten feed is a byproduct of the wet milling process. Wet milling separates the corn kernel into starch, oil, protein, and bran. Corn gluten feed is not to be confused with corn gluten meal. Corn gluten meal has two times the protein content of corn gluten feed. Also the protein in corn gluten feed is degraded relatively rapidly in the rumen versus the protein of corn gluten meal is degraded relatively slowly (more by-pass potential).
Corn gluten feed, after processing, starts in a wet form. Wet corn gluten feed has some nutritional advantages over dry corn gluten feed but the dry product is easier to handle. Wet corn gluten feed has a bunk life of a few days in summer and one to two weeks in winter. Because of bunk life and transportation costs, wet corn gluten feed is only an option to producers that are in relative close proximity of the milling plant.
Crude protein values have range from 17 percent to 26 percent and fat content has ranges from 1 to 7 percent. Therefore, regular feed testing is recommended or buy corn gluten feed that has a guaranteed analysis. This is true of most by-product feeds.
The concentration of crude protein is about as twice as high in corn gluten feed as it is in corn grain. Corn gluten feed is low in calcium but has significant amounts of phosphorus. The calcium to phosphorus ratio is about 1:10. The desired ratio of feeding cattle is a minimum of 1.5-2 to 1 calcium to phosphorus. Therefore, corn gluten feed fed at high levels without calcium supplementation could result in urinary calculi problems. It is necessary to feed calcium levels above NRC minimum requirements if more than 1/3 of the diet is corn gluten feed. Trace mineral and vitamin levels can vary greatly from batch to batch.
CORN GLUTEN FEED AS A PROTEIN SOURCE: Gluten feed can be used in products formulated to meet the protein requirements of beef cattle. When the diets are similar in energy, corn gluten feed is approximately equal to soybean meal as a protein source. Therefore, if soybean meal (44 percent crude protein) is worth $200/ton, then dried corn gluten feed would be worth about $84/ton as a protein source. However, quality of amino acid content is lower for corn gluten feed than soybean meal.
CORN GLUTEN FEED AS AN ENERGY SOURCE: Corn grain has a higher energy content than corn gluten feed. However, corn gluten feed may be equal to corn as an energy supplement in forage-based diets. Corn grain can depress forage (fiber) digestibility, where as, corn gluten feed does not appear to depress fiber digestibility IN SIMILAR FEEDING CIRCUMSTANCES
In low silage diets (10 percent silage), wet corn gluten feed has an energy value of 95 percent of corn and dry corn gluten feed has an energy value of about 86 percent of corn. In medium silage diets (40 percent corn silage), dry corn gluten feed is worth 92 percent of corn and wet corn gluten feed has an energy value of 95 percent of corn. In high silage diets (70 percent corn silage), wet corn gluten feed and dry corn gluten feed have energy values about 102 percent of corn. Differences between wet and dry corn gluten feed may be due to differences in particle size and/or heat damage during the drying process.
CARCASS CHARACTERISTICS AND HEALTH: Corn gluten feed does not appear to affect carcass characteristics or chemical composition of the carcass of finishing cattle. No differences in incidence of liver abscesses have been observed. An unconfirmed case of polioencephalomalacia (PEM) was reported when a large amount of freshly made wet corn gluten feed was fed. Some nutritionists recommend that cattle be supplemented with thiamin when large amounts of wet corn gluten feed are being fed for PEM prevention. When corn gluten feed is fed at greater than 35-40 percent of the diet, thiamine supplementation at the rate of 400 mg per head per day should be considered to prevent a deficiency and the resulting possibility of PEM. Another possibility may be related to potentially high levels of sulfur found in corn gluten feed from time to time which can produce similar symptoms in some cases.
Soyhulls and Corn Gluten Feed are only two of many by-products which are available for feeding of cattle. In the next issue we will continue this series by examining more products of this nature.
Dr. Steve Blezinger is a nutritional and management consultant with an office in Sulphur Springs, TX. He can be contacted at Route 4 Box 89 Sulphur Springs, TX 75482, by phone at (903) 885-7992 or by e-mail at firstname.lastname@example.org.