Four methods of ensiling sorghum-sudan 9.2b arrd 9.5ab, and, mean milk yields (kg/ grass were compared: A, field wilted to an day) were 16.2a, 16.5a,'17.2b and l6.4afor average moisture content of. 69Vo prior to treatments A, B, C, and D, respectively (where chopping; B, direct cut and chopped; C, direct means followed by the same letter were not cut and chopped with O.5% w/w of.9OVo significantly different; P < 0.05). Digestibiliformic acid added at time of ensiling; and D, ties of dry matter, fiber and energy were direct cut and chopped with l.5Vo w/w mo-significantly lower (P < 0.05) for the formic lasses added during the ensiling process; The acid-treated than for the wilted silage. The four silages were fed successively to each of efficiency of energy utilization for milk yield 16 lactating cows over periods of 56 days ac-plus body gain was greater (P q 0.05) for cording to a changeover design. Mean silage formic acid silage than for any other treatdry matter intakes (kglday) werc 1.0.0a,9.|b, ment.