COOL-SEASON ANNUAL LEGUME EFFECTS ON WHEAT FORAGE NUTRITIVE-VALUE

Hard red winter wheat (Triticum aestivum L. amend. Thell.) is an impor tant cool-season win ter forage used primarily for increasing weight g ain on growing beef cattle in the southern Great Plains. 'Karl' hard r ed winter wheat grown alone or grown with either hairy vetch (Vicia vi llosa Roth) or pea [(Pisum sativum L. subsp. arvense) var. 'Austrian w inter'] was sampled for forage nutritive value. The interplanted legum e forage was also sampled for forage nutritive value. Ruminally degrad able nitrogen (RDN): ruminally degradable organic matter (RDOM) ratios were highest for legume forage and exceeded the National Research Cou ncil (NRC) recommendation of 26.13 g KDN:1 kg RDOM for peak ruminal mi crobial efficiency during March, April, and May sample periods over th e 2-year study. Wheat grown alone met the NRC requirement only during March. Wheat grown with either hairy vetch or pea had higher (P<0.05) RDN:RDOM ratios and crude protein (CP) values when compared to wheat g rown alone during May. There were no differences (P>0.05) in dry matte r (DM) yield between wheat grown alone or grown with the legumes excep t when analyzed by individual date, and then only for 1 of 6 sample da tes. Undegraded intake protein (UIP) was generally higher (P<0.05) for wheat compared to the legumes and higher (P<0.05) for wheat grown alo ne during May compared to wheat grown with the legumes during May. The decline of the RDN:RDOM values to 40% below the NRC recommendation of wheat grown alone during May indicates a possible need for protein su pplementation for growing beef cattle grazing wheat during this period . These data also indicate that interplanting legumes with wheat may e nhance animal performance by providing forage of higher nutritive valu e. More information regarding grazing tolerance of these selected cool -season annual legumes and subsequent animal performance is required.