A Note On High-Oil Corn
Livestock Update, April 1998
Allen Harper, Extension Animal Scientist, Swine, Virginia Tech
High-oil corn is a variety of corn that has been genetically selected to contain a greater oil (fat) content in the kernel than would be contained in current "standard" varieties of corn. Genetic engineering or manipulation has not been part of the technology involved in developing the high-oil corn varieties available at this time. Instead, standard genetic selection procedures with criteria that favor higher oil content have been used. Actually varieties selected for high oil content have a larger germ portion in the corn kernel. Because most of the oil in corn grain is contained in the germ portion, then a larger germ fraction results in greater oil content of the total kernel. It is noteworthy too that the corn germ fraction also contains protein and consequently some high-oil corns tend to have slightly higher protein (and amino acid) level as well.
How much more oil does a high-oil corn have? There is variation in the amount of increased oil content. This is to be expected due to differences in growing seasons, soil type, fertility and other factors. However, current information indicates that high-oil corn will typically contain about 80% more oil than standard varieties. While this is certainly a significant increase, it is important to understand that corn is not inherently rich in oil. Standard corns will typically contain about 3.5 % oil and current high-oil corns will typically contain about 6.3 %. A recent ether extract analysis on standard and high-oil corns grown in 1997 on a farm near Luray, Virginia indicated 4.39 % oil in the standard corn and 6.34 % oil in the high-oil variety.
Corn is the predominant feed grain in the diets of pigs and poultry and as such it supplies most of the energy in the diet for these species. Corn grain may also be included in the rations of feed-lot cattle and dairy cattle to enhance energy consumption. Oil or fat has approximately 2.2 times more metabolizable energy value than carbohydrate and for this reason high-oil corn will be higher in metabolizable energy than standard corn. Indeed the most significant potential advantage of high-oil corn is greater energy density for animals that require energy dense diets such as growing pigs, lactating sows or growing broilers or turkeys. Recent experiments indicate a metabolizable energy advantage for high-oil corn of about 70 more kilocalories per pound of corn when fed to pigs and about 80 more kilocalories per pound of corn when fed to poultry.
For growing-finishing market pigs, adequate energy density in the diet is important for rapid growth rate and efficient feed conversion. In many situations feed grade fats are added to grower diets at levels of 3 to 6 % to increase diet energy levels. This practice can be especially beneficial in during hot weather months when feed consumption rates are poor due to temperature stress. Lactating sows can also benefit from fat supplemented diets to help meet the energy demands for milk production. It is apparent that utilizing high-oil corn has much the same impact as adding feed grade fat to swine diets. A recent trial conducted by Animal Scientists at Continental Grain Company and DuPont Agricultural Products illustrates this point. The trial involved 184 growing-finishing pigs with an average starting weight of 44 lbs. The pigs were assigned to three feeding programs: a standard corn-soy diet, a corn-soy diet in which high-oil corn replaced standard corn on an equal weight basis, and a standard corn-soy diet with just enough feed grade fat supplementation to have a similar fat level as the high-oil corn diet. Pig growth rate during the sixteen-week trial was identical for each of the three feeding programs. However, pigs fed the high-oil corn and the fat added diets consumed about 3.6 % less feed than the pigs fed standard corn-soy diets. Furthermore, the high-oil corn and fat added diets resulted in a 5.1 % improvement in feed conversion efficiency. The trial clearly showed that using high-oil corn in growing pig diets has the same impact as adding feed grade fat to the diet. Because these diets had greater energy density, the pigs consumed less feed to meet their energy requirements but grew as fast and more efficiently than pigs fed the standard corn-soy diet.
Performance of Growing-Finishing Pigs Fed High-Oil Corn*
No Added Fat
+ Added Fat
|Daily Feed Intake, lbs.||5.09x||4.85y||4.96y|
|Lbs. Feed/lb Gain||2.72x||2.58y||2.58y|
The added value of high-oil corn above standard corn grain will certainly be related to the added energy and nutrient density of the grain. A competing factor at large feed mills that have the capacity store and use feed grade fat products would be the cost of feed grade fats. When the cost of feed grade fat declines, this would put negative pressure on the amount of added value paid for high-oil corn. Conversely, as the cost of purchasing and incorporating feed grade fats increases, this would be positive to the added value that high-oil corn may generate. Other factors that will impact the potential value of high-oil corn include the willingness and ability of grain buyers to maintain separate identity and storage for high-oil corn. Furthermore, the adoption of high-oil corn production by grain farmers will be dependent on the potential to earn more return than if standard varieties were produced. For smaller farm feeding operations that cannot justify the expense of fat tanks or dry fat supplements, high-oil corn production or purchase does offer a means of getting increased energy density in some diet formulations that are prepared on the farm.
Adeola, O., and N. L. Bajjalieh. 1997. J. Animal Science, Vol. 75:430. Dudley-Cash, W. 1996. Feedstuffs, May 6, 1996, page 12. Risley, C. R., and N. L. Bajjalieh. 1996. J. Animal Science, Vol. 74(Suppl. 1):176.