Effects of different fresh-cut forages and their hays on feed intake, digestibility, heat production, and ruminal methane emission by Boer x Spanish goats.

摘要

Twenty-four yearling Boer x Spanish wethers were used to assess effects of different forages, either fresh (Exp. 1) or as hay (Exp. 2), on feed intake, digestibilities, heat production, and ruminal methane emission. Treatments were: (1) Sericea lespedeza (SER; Lespedeza cuneata), a legume high in condensed tannins (CT; 20 and 15 in fresh forage and hay, respectively), (2) SER supplemented with polyethylene glycol (SER-PEG; 25 g/d), (3) alfalfa (Medicago sativa), a legume low in CT (ALF), and (4) sorghum-sudangrass (Sorghum bicolor), a grass low in CT (GRASS). Experiments were 22 d, which included 16 d for acclimatization followed by a 6-d period for fecal and urine collection, and gas exchange measurement (last 2 d). Intake of OM was 867, 823, 694, and 691 g/d (SEM=20.1) with fresh forage, and 806, 887, 681, and 607 g/d with hay for SER, SER-PEG, ALF, and GRASS, respectively (SEM=46.6). Apparent total tract N digestion was greater for SER-PEG vs. SER (P5/ml; SEM=2.76) and hay (P5/ml for SER, SER-PEG, ALF, and GRASS, respectively; SEM=1.43). Methane emission as a percentage of DE intake was lower (P<0.01) for SER vs. ALF and GRASS with fresh forage (6.6, 8.3, 9.4, and 9.2; SEM=0.64) and hay (4.3, 4.9, 6.4, and 6.7 for SER, SER-PEG, ALF, and GRASS, respectively; SEM=0.38). In summary, methane emission in this short-term experiment was similar between a legume and grass low in CT as fresh forage and hay. The CT in SER markedly decreased N digestibility and elicited a moderate decline in ruminal methane emission. Supplementation with PEG alleviated the effect of CT on N digestibility but not ruminal methane emission, presumably because of different modes of action. In conclusion, potential of using CT-containing forage as a means of decreasing ruminal methane emission requires further study, such as with longer feeding periods.CAS Registry Numbers 74-82-8 25322-68-3