| Abstract | Thirty-six mature Boer goat wethers were supplemented with 0.5% BW (DM) of rolled corn and consumed pelleted alfalfa hay (CON), pelleted Sericea lespedeza hay (HSL; 6.4% condensed tannins), a 1:1 mixture of alfalfa and lespedeza (MSL), or alfalfa with monensin (ION; 22 mg/kg), coconut oil (CCO; 4%), or soybean oil (SBO; 4%). Total DMI in the 20-wk study (3.86, 3.75, 3.52, 3.69, and 3.64% BW; SEM = 0.157) and total tract OM digestibility determined every 5 wk (72.8, 69.5, 70.3, 72.0, and 71.1%; SEM = 1.80) were not affected by treatment (P > 0.05), although there were differences (P < 0.05) in N digestion (77.5, 70.7, 67.0, 77.0, 75.7, and 73.6% for CON, MSL, HSL, ION, CCO, and SBO, respectively; SEM = 1.76). Ruminal methane emission was not influenced by period or treatment × period (P > 0.05) but was greatest among treatments for CON expressed as percentages of gross (10.3, 6.8, 6.3, 7.2, 6.5, and 6.5%; SEM = 0.35) and digestible energy (14.8, 10.2, 9.3, 10.6, 9.8, and 10.1% for CON, MSL, HSL, ION, CCO, and SBO, respectively; SEM = 0.62). In conclusion, with rolled corn at 14-15% of the diet a 1:1 mixture of pelleted alfalfa and a source of lespedeza, with a low to moderate level of CT, had similar effect on ruminal methane emission as lespedeza as the sole forage (31 and 37% decreases relative to DE intake, respectively). Inclusion in basal alfalfa diets of monensin at approximately 22 mg/kg DMI and coconut and soybean oils at 4% elicited similar decreases in methane emission (28, 34, and 32%, respectively). There was no evidence of adaptation to any of the modifiers, with methane emission determined in wk 5, 10, 15, and 20. |
