Evaluation of Warm-Season Legumes for Nutritive Values and Digestibility.

The cultivation of forage legumes is beneficial to livestock producers due to production of nutritious and highly digestible forages with low nitrogen fertilizer application. In the southern US, alfalfa is not always as productive as in the northern US because of high temperature, humidity, and diseases. Warm-season legumes adapted to the southern US may be alternative legume forage sources. However, nutritive values and digestibility have not been studied much and more information is needed to adopt a current digestibility evaluation system. Five warm season legumes: Strophostyles helvula, Lablab purpureus, Kummerowia stipulacea, Glycine max, and Arachis glabrata were incubated with rumen fluid for up to 48 hrs to compare the fermentation behaviors and digestibility at 18, 24, 36, and 48 hr. The IVTDs of G. max. K. stipulacea, S. helvula, and A. glabrata at 36 hr were significantly different from 24 hrs (P<0.05) but not significantly different from those at 48 hr. Compared with the gas production dynamics of M. sativa, warm-season legume forages showed longer lag time and less gas production. This demonstrated substantial differences in nutrient degradation rates between alfalfa and non-conventional legume forages in the rumen.