| Abstract | Fifty-four Alpine doelings (31.7±0.38 kg BW and 306±1.9 d) consumed 75% forage diets ad libitum in a 12-wk trial with 2 6-wk periods. Alfalfa was the forage in control (C) and other diets consisted of Sericea lespedeza with 1.25% DM of quebracho extract in concentrate, for a condensed tannin level of 8.4%. Lespedeza treatments were no additive (L) and inclusion of monensin (I) at 22 mg/kg (DM; L-I), soybean oil (SBO) at 3% (L-S), coconut oil (CCO) at 3% (L-N), I and 3% SBO (L-I-S), I and 3% CCO (L-I-N), 1.5% SBO and 1.5% CCO (L-S-N), and I, 1.5% SBO, and 1.5% CCO (L-I-S-N). The C diet averaged 16.7% CP, 43.8% NDF, and 8.8% ADL, and the L diet was 12.7% CP, 42.8% NDF, and 13.2% ADL. There were no treatment×period interactions (P>0.05). Intake of DM was 1.47, 1.27, 1.29, 1.19, 1.33, 1.14, 1.08, 1.14, and 0.98 kg/d (SEM=0.064) and ADG was 122, 79, 89, 83, 100, 76, 70, 78, and 65 g for C, L, L-I, L-S, L-N, L-I-N, L-S-N, and L-I-S-N, respectively (SEM=9.7). Total tract digestibilities of OM (57.4, 50.9, 51.8, 52.7, 50.3, 52.1, 52.1, 51.9, and 49.8%; SEM=1.42) and N (59.1, 31.2, 32.5, 37.1, 31.6, 38.3, 30.4, 38.4, and 34.1% for C, L, L-I, L-S, L-N, L-I-N, L-S-N, and L-I-S-N, respectively; SEM=2.21) were greater for C than for lespedeza treatments (P<0.05). Ruminal methane emission was lower (P<0.05) for diets with lespedeza relative to GE (5.92, 3.27, 3.49, 3.19, 2.84, 2.91, 3.20, 3.20, and 3.27%; SEM=0.165) and DE (11.19, 6.98, 7.40, 6.38, 5.90, 5.69, 6.37, 6.38, and 6.70% for C, L, L-I, L-S, L-N, L-I-N, L-S-N, and L-I-S-N, respectively; SEM=0.400). In conclusion, the effect of tannins on methane did not diminish over time and was not influenced by monensin, soybean oil, or coconut oil. |
