American Institute for Goat Research, Langston University, Langston, OK 73050, USA.
J Anim Sci. 2012 Aug;90(8):2754-62. doi: 10.2527/jas.2011-4879. Epub 2012 Mar 9.
Twenty-four yearling Boer × 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 (P < 0.001) with fresh forage (46.3%, 66.5%, 81.7%, and 73.2%; SEM = 1.71) and hay (49.7%, 71.4%, 65.4%, and 54.8% for SER, SER-PEG, ALF, and GRASS, respectively; SEM = 1.57). Intake of ME was similar among treatments with fresh forage (8.24, 8.06, 7.42, and 7.70 MJ/d; SEM = 0.434) and with hay was greater for SER-PEG than ALF (P < 0.03) and GRASS (P < 0.001) (8.63, 10.40, 8.15, and 6.74 MJ/d for SER, SER-PEG, ALF, and GRASS, respectively; SEM = 0.655). The number of ciliate protozoa in ruminal fluid was least for SER with fresh forage (P < 0.01) (9.8, 20.1, 21.0, and 33.6 × 10(5)/ml; SEM = 2.76) and hay (P < 0.02) (6.3, 11.4, 13.6, and 12.5 × 10(5)/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.
24 头一岁的布尔山羊 × 西班牙小尾寒羊被用于评估不同饲草（新鲜饲草，实验 1；干草，实验 2）对采食量、消化率、产热量和瘤胃甲烷排放的影响。处理方式为：1）绢毛胡枝子（Sericea lespedeza，Lespedeza cuneata），一种富含单宁（CT）的豆科植物（新鲜饲草中分别为 20%和 15%，干草中分别为 15%和 10%）；2）用聚乙二醇（PEG）补充的绢毛胡枝子（SER-PEG）；3）紫花苜蓿（Medicago sativa），一种 CT 含量低的豆科植物（ALF）；4）高粱-苏丹草（Sorghum bicolor），一种 CT 含量低的禾本科植物（GRASS）。实验持续 22 天，其中包括 16 天的适应期和 6 天的粪便和尿液收集以及气体交换测量期（最后 2 天）。新鲜饲草时，OM 的采食量分别为 867、823、694 和 691 g/d（SEM = 20.1），干草时，SER、SER-PEG、ALF 和 GRASS 的采食量分别为 806、887、681 和 607 g/d（SEM = 46.6）。新鲜饲草时，与 SER 相比，SER-PEG 增加了总肠道 N 消化率（P < 0.001）（46.3%、66.5%、81.7%和 73.2%；SEM = 1.71），干草时（49.7%、71.4%、65.4%和 54.8%，SER、SER-PEG、ALF 和 GRASS，SEM = 1.57）。新鲜饲草和干草时，ME 的摄入量相似（新鲜饲草时分别为 8.24、8.06、7.42 和 7.70 MJ/d；SEM = 0.434；干草时分别为 8.63、10.40、8.15 和 6.74 MJ/d，SER、SER-PEG、ALF 和 GRASS，SEM = 0.655）。与新鲜饲草相比，SER-PEG 降低了瘤胃液体中纤毛虫原虫的数量（P < 0.01）（9.8、20.1、21.0 和 33.6 × 10（5）/ml；SEM = 2.76）和干草（P < 0.02）（6.3、11.4、13.6 和 12.5 × 10（5）/ml，SER、SER-PEG、ALF 和 GRASS，SEM = 1.43）。与 ALF 和 GRASS 相比，SER 降低了 DE 摄入的甲烷排放百分比（P < 0.01）（新鲜饲草时分别为 6.6、8.3、9.4 和 9.2%；SEM = 0.64）和干草（4.3、4.9、6.4 和 6.7%，SER、SER-PEG、ALF 和 GRASS，SEM = 0.38）。总之，短期试验中，作为新鲜饲草和干草，富含 CT 的豆科植物与 CT 含量低的禾本科植物的甲烷排放相似。绢毛胡枝子中的 CT 显著降低了 N 消化率，并导致瘤胃甲烷排放适度降低。PEG 补充缓解了 CT 对 N 消化率的影响，但对瘤胃甲烷排放没有影响，这可能是由于作用方式不同。总之，使用含 CT 饲草作为降低瘤胃甲烷排放的一种手段需要进一步研究，例如采用更长的饲养期。
