Modified Grain and Animal Performance

The starch component of conventional corn is comprised of amylose (~22%) and amylopectin (~78%). Is there any advantage to changing the amylose: amylopectin in corn? Corn with essentially 100% of its starch as amylopectin is called waxy corn. Some studies suggest that amylopectin may have a higher net energy value for swine than amylose. That is because amylopectin may be more rapidly digested than amylose, indicating that more amylopectin than amylose is digested in the small intestine. Starch digested in the small intestine (i.e., yielding glucose) has a greater net energy value than starch that reaches the large intestine. However, significant improvements in feed efficiency of pigs fed waxy grain have not been observed. The author is not aware of trials comparing the growth performance of pigs fed high amylose corn to conventional corn.

Corn containing more oil than conventional corn consistently improves feed efficiency in swine. That is because swine consume the quantity of feed necessary to meet their energy needs. One pound of oil or fat contains 2.25 times more metabolizable energy than one pound of starch. Therefore, higher fat diets reduce feed intake, but swine will consume the same or sometimes more calories than when consuming lower fat diets. Daily gain may increase when diets contain higher concentrations of fat.

The expected improvement in feed efficiency for pigs consuming diets containing 5.5 or 7.5% oil corn is shown in Figure 20. In Figure 21 is an estimate of the annual gross savings from feeding high oil corn to growing-finishing swine.

Swine deposit the kind of fat they consume in their body or products they produce. If the dietary mixture of fatty acids is changed to be more saturated, pork fat will be more saturated (i.e., firmer). Therefore, altering the fatty acid content of corn may offer possibilities for producing “designer” pork products. For example, high-oleic acid (18:1) corn should improve the processing and storage of pork, because there will be a reduced proportion of unsaturated fatty acids (i.e., 18:2) in the carcass.

Diets containing normal and high-lysine corn are shown in Figure 22. Due to the difference in the lysine content of corn, the diet containing high-lysine corn contains 60 lb less soybean meal per ton of complete feed. Research indicates that growth performance is similar whether pigs are fed normal-or high-lysine corn-based diets. Figure 23 shows annual gross savings from substituting high-lysine corn for normal corn in the diet for growing-finishing pigs.

Several studies indicate that growth performance of swine fed corn genetically modified for agronomic benefits is equivalent to non-transgenic corn. Moreover, the composition of meat is not affected when pigs consume genetically modified corn.