Abstract
Eighteen Katahdin (initial body weight of 74 kg; SEM=1.8) and 18 St. Croix ewes (55 kg; SEM=1.3) were used in an experiment with four 6-wk periods to determine effects of dietary level of Sericea lespedeza (Lespedeza cuneata) containing 5.8% condensed tannins (dry matter; DM) and other supplemental ingredients on feed intake, digestion, and ruminal methane emission. Diets were consumed ad libitum and included a concentrate supplement at 0.45% BW (DM). Alfalfa was the basal forage for control (CON), ionophore (ION; lasalocid at 33 mg/kg DM), coconut oil (3%; CCO), and soybean oil (3%; SBO) diets, and forage in moderate- and high-lespedeza diets was a 1:1 mixture of alfalfa and lespedeza and all lespedeza, respectively (MSL and HSL, respectively). Data were analyzed with a 2 x 6 factorial arrangement of treatments, period as a repeated measure, and a mixed effects model. Digestion and methane emission were determined in weeks 4, 10, 16, and 22. Total DM intake was similar among treatments (P = 0.070) but numerically greatest for HSL (1,197, 1,297, 1,491, 1,203, 1,195, and 1,207 g/d; SEM=81.1), OM digestibility ranked (P < 0.05) CON, ION, CCO, and SBO > MSL > HSL (69.2, 57.6, 50.3, 66.3, 66.0, and 68.7%; SEM=1.57), and digestible OM intake was similar among treatments (P = 0.517; 697, 607, 589, 598, 635, and 690 g/d for CON, MSL, HSL, ION, CCO, and SBO, respectively; SEM=50.4). There were no interactions involving time in ruminal methane emission, which was greatest among treatments for CON (P < 0.05) in MJ/d (1.39, 0.93, 0.90, 0.92, 0.85, and 0.96; SEM=0.069) and relative to digestible energy intake (20.6, 15.7, 16.8, 16.1, 13.7, and 13.9% for CON, MSL, HSL, ION, CCO, and SBO, respectively; SEM=1.223). In conclusion, dietary inclusion of Sericea lespedeza may offer a natural and sustainable means of decreasing ruminal methane emission by hair sheep as previously shown in goats, with a magnitude of impact similar to that of some other supplemental dietary ingredients.
Methods for instrumental assessment of methane emission in reservoirs
