Abstract 255

Brown,-WF; Phillips,-JD; Jones,-DB

Agricultural Research and Education Center, Univ. Florida, Ona, FL 33865, USA.

Journal-of-Animal-Science. 1987, 64: 4, 1205-1214; 43 ref.

In 3 digestion and 2 cattle growth studies ammoniation level or the nutritional value of ammoniated forage relative to nontreated forage plus a molasses-urea supplement was studied. In trial 1, mature limpograss (Hemarthria altissima) was treated with anhydrous ammonia at 0, 2, 3 or 4% of DM and fed to steers (217 kg) in a digestion trial. Increases (P <0.01) in the apparent digestion coefficients of organic matter (OM), neutral detergent fibre (NDF), acid detergent fibre (ADF) and hemicellulose (HC) resulting from increased level of ammoniation were significant for the linear contrast. Urea or cane molasses and urea were added to non-treated limpograss (digestion trial 2, growth trial 1) or rice straw, (digestion trial 3, growth trial 2) and compared with ammoniated forage (NH3 4 g/100 g DM). Growth trial 1 (63 steers, 220 kg) and 2 (54 steers, 277 kg) lasted 94 and 91 days, respectively. Ammoniation increased (P <0.05) apparent digestion coefficients of OM, NDF, ADF and HC compared with non-treated forage plus urea or molasses-urea. Steers fed on ammoniated forage had improved (P <0.05) DM intake (DMI), daily gain (ADG) and gain/feed (G/F) compared with those fed on non-treated forage plus urea. Steers fed on ammoniated limpograss had similar DMI but improved (P <0.05) ADG and G/F compared with those fed on limpograss molasses-urea; steers fed on ammoniated rice straw had similar DMI, ADG and G/F compared with those fed on rice straw molasses-urea. Molasses-urea addition to non-treated forage resulted in similar OM digestibility, but reduced (P <0.05) digestibilities of NDF, ADF and HC compared with non-treated forage plus urea. Steers fed on limpograss molasses-urea had increased (P <0.05) DMI and ADG, but similar G/F compared with those fed on limpograss plus urea; steers fed on rice straw molasses-urea had improved (P <0.05) DMI, ADG and G/F compared with those fed on rice straw plus urea.