Rations fed in Group I include hay and grain in about equal amounts. Alfalfa represents high protein forages, which primarily need to be supplemented with energy in the grower. The grass hays, including brome, orchardgrsss and all small grain forages, require a higher protein concentrate to provide both supplemental energy and protein for the growing heifer. Hay-crop silages are usually not fed to calves during this phase because they are not consumed as well as hays. Although studies indicate that corn silage can be fed, the small quantity consumed daily would produce problems in keeping it bunk fresh.
Hays are simply easier to manage.
Also, the percent protein and the energy concentration required in their feed are less than those needed for younger calves. For these reasons, rations can be formulated for calves of this size at a lower cost per unit dry matter than for younger calves. With these roughages, free-choice mineral feeding will meet the heifer's mineral requirements. Rations 7 and 8 use urea as the total supplemental nitrogen and, therefore, are lower in cost than rations containing other protein supplements. In addition, NPN is better utilized when consumed at frequent intervals as part of the total ration compared to including NPN only in the grower mix which is fed once daily.