Interactional Digestible, Metabolized and Net Energy Values of Wheat and Barley in Swine

Metabolism and growth experiments were conducted with barrows to determine the digestible, metabolizable and net energy for maintenance and production of barley and wheat diets in which each of the two grains varied inversely in 10% increments from 0 to 100% of the total grain component of the diet. There was a linear relationship between the ration DE and MEnvalues and the wheat and barley content of the diet. The dietary DE and MEnvalues (kcal/g) of wheat were 3.51 and 3.34; those of barley were 3.12 and 2.95. There was a trend which suggested an interactional effect of barley and wheat as components of the ration on the DE and MEnvalues. Animals fed the barley-wheat rations during the fall season consumed more feed and had a greater daily live weight gain than those fed during the summer. There was a linear relationship between the net energy value and the wheat component of the rations for those animals fed during the fall; the NEm+pvalue of barley and wheat was 2.06 and 2.40 kcal/g, respectively. However, in the summer growth study there was a curvilinear relationship (third order) between the net energy value and the amount of each grain in the rations. The NEm+pof barley varied from 1.75 to 2.64 kcal/g and that of wheat ranged from 1.85 to 2.65 kcal/gram. The NEm+pvalue of barley and wheat fed as 100% of the grain portion of the diet was 2.11 and 2.22 kcal/g, respectively; the same variety of wheat was more efficiently utilized in the fall than in the summer trial. The interactional effect of dietary wheat and barley was observed to be in the utilization of ME for NEm+p. The animals' growth response and carcass characteristics were indicative of the net energy value of the rations and feed intake. The implications of a possible interactional phenomenon of dietary ingredients should not be ignored when evaluating feedstuffs and efficiency of swine production.