Journal of the NACAA
ISSN 2158-9429
Volume 1, Issue 1 - July, 2008


Relative Feed Value and Crude Protein of Selected Cool and Warm Season Forages in Response to Varying Rates of Nitrogen

Angima, S.D., Assistant Professor, Oregon State University Extension Service
Kallenbach, R.L., Professor, Plant Science Unit, University of Missouri


Cool season forages produce most of their biomass during spring and early summer and early winter, while warm season forages are productive during hot summers therefore filling in the slump left by cool season grasses. To most livestock farmers, crude protein (CP) and relative feed values (RFV) are the basis for buying or making hay for livestock. Our objective was to determine crude protein and relative feed values from a range of cool and warm season forages harvested as hay when grown under four different rates of nitrogen (0, 50, 100, & 150 lb/acre). Cool season forages included Fescue K-31, Max QTM fescue, CowPro fescue, Timothy, Smooth Bromegrass, and Orchard grass, and warm season forages Bermudagrass, Switchgrass, Eastern gamagrass, Indiangrass, Little bluestem, and Big bluestem. Forages were harvested once each growing season near LaDue Missouri. Percentage CP levels ranged from 6.4% to 9.2% and 3.4% to 7.1% for cool and warm season forages respectively and generally increased with increasing nitrogen rates. There were no significant differences in CP levels for all the nitrogen rates except for CowPro fescue, Bermuda grass, and Indian grass forages. Relative feed values ranged from 93 to 104 and 84 to 98 for cool and warm season forages, respectively. There were no significant differences in RFV for both cool and warm season forages under all levels of nitrogen used. Nitrogen did influence CP and RFV but not as much as it has been shown to influence yield.
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