G.E. BRINK and T.E. FAIRBROTHER
USA Department of Agriculture, Agricultural Research Service, P.O. Box 5367, Mississippi State, MS 39762, USA.
A majority of the cool-season legumes utilised for pasture in the Southeastern USA lack productivity or persistence during the hot, dry months of June, July and August. More information is needed concerning the forage potential of various legumes for this major pasture region of the USA. Our objective was to compare the nutritive value, relative palatability and yield of selected cool- and warm-season legumes grown during the summer months. Fifteen cool- and warm-season legumes were sown in late spring or early summer in 1985 and 1986 at Mississippi State, MS. Dry matter yield and nutritive value were measured twice each summer before selective grazing by ewes to measure palatability.
At the first harvest in both years (mid-June to late July), the crude protein and in vitro digestible dry matter concentration of aeschynomene (Aeschynomene amerciana L.) and cowpea (Vigna unguiculata (L.) Walp.) were similar to or greater than that of red clover (Trifolium pratense L.) or lucerne (Medicago sativa L). Dry matter yields were variable and tended to be influenced by planting date. Aeschynomene, alyceclover (Alysicarpus vaginalis (L.) DC), and lucerne were as palatable as red clover in both years. At the second harvest in both years (late August), the digestibility of aeschynomene and alyceclover was equal to or greater than that of lucerne and red clover (mean of 683 g/kg), while the digestibility of phasey bean (Macroptilium lathyroides (L.) Urb.) was only 3 to 6% less than either cool-season legume. Dry matter yield of aeschynomene, alyceclover, and phasey bean was 1 to 4 times as great as that of lucerne. Palatability of all warm-season legumes was considerably lower than that of the cool-season legumes. These results indicate that selected warm-season legumes have potential to provide greater quantities of high quality forage, particularly for late summer grazing, than lucerne or red clover, and to reduce deficiencies of quality feed common during this time period.