Key Laboratory of Animal Nutrition and Feed Science in South China, Ministry of Agriculture and Rural Affairs, Guangdong Key Laboratory of Animal Breeding and Nutrition, Institute of Animal Science, Guangdong Academy of Agricultural Sciences, Guangzhou, China.
Agriculture and Agri-Food Canada, Lethbridge Research and Development Centre, Lethbridge, Alberta, Canada.
J Sci Food Agric. 2021 Feb;101(3):1247-1254. doi: 10.1002/jsfa.10913. Epub 2020 Nov 20.
The objective of this study was to determine the effects of forage conservation method and condensed tannins (CT) in conserved forage on rumen fermentation. Purple prairie clover (PPC; Dalea purpurea Vent.) containing 84.5 g kg dry matter (DM) of CT was harvested at full flower and preserved as freeze-dried green chop (F), hay (H) or silage (S). Batch culture incubations were conducted using conserved forages as a substrate and treatments were arranged as 3 × 2 factorial design of forage type (F, H and S) with or without polyethylene glycol (PEG). PEG was used to isolate the effects of CT on fermentation. Incubation was repeated twice with quadruplicate vials for each treatment in each incubation. N-labelled ammonium sulfate was used as microbial N marker and headspace gas was sampled to determine methane production.
Concentrations of neutral detergent fiber (NDF) and acid detergent fiber were lower (P < 0.01) in F than in H or S. Ensiling decreased (P < 0.001) total phenolics and extractable CT, but had no effect on total CT, whereas none of these phenolic fractions were altered in H. Hay and silage had lower (P < 0.01) true DM disappearance (TDMD) and NDF disappearance (NDFD) than F. Inclusion of PEG did not affect TDMD or NDFD after 8, 24 or 72 h of incubation. Productions of total gas, methane and total volatile fatty acid and the rate of gas production (c) were also similar, but ammonia was higher (P < 0.05) and microbial N was lower (P < 0.05) with than without PEG after 72 h of incubation. After 72 h, a lower (P < 0.001) proportion of acetate but higher (P < 0.05) proportion of propionate was noted with S, resulting in a lower (P < 0.001) acetate:propionate ratio as compared to F or H after 8 h of incubation.
Condensed tannins in PPC decreased protein degradation in vitro, but had minimal effects on overall rumen fermentation, and conservation of PPC as hay or silage had little effect on the efficacy of CT in modulating rumen fermentation. © 2020 Her Majesty the Queen in Right of Canada. Journal of The Science of Food and Agriculture © 2020 Society of Chemical Industry.
本研究旨在确定饲草保存方式和保存饲草中的单宁（CT）对瘤胃发酵的影响。含有 84.5g/kg 干物质（DM）CT 的紫三叶草（PPC； Dalea purpurea Vent.）在完全开花时收获，并保存为冻干绿碎料（F）、干草（H）或青贮料（S）。使用保存的饲草作为底物进行批量培养孵育，处理方式为 3×2 因素设计，包括饲草类型（F、H 和 S）和是否添加聚乙二醇（PEG）。PEG 用于分离 CT 对发酵的影响。每个孵育重复两次，每个处理有 4 个重复小瓶。使用 15N 标记的硫酸铵作为微生物 N 标记物，取样顶空气体以确定甲烷产量。
F 中的中性洗涤纤维（NDF）和酸性洗涤纤维浓度较低（P<0.01），比 H 或 S 低。青贮降低了（P<0.001）总酚类物质和可提取 CT，但对总 CT 没有影响，而 H 中没有改变这些酚类物质。干草和青贮的真 DM 消失率（TDMD）和 NDF 消失率（NDFD）均低于 F（P<0.01）。孵育 8、24 或 72 小时后，PEG 的添加不影响 TDMD 或 NDFD。总气体、甲烷和总挥发性脂肪酸的产生以及产气量（c）也相似，但 72 小时后添加 PEG 会导致氨更高（P<0.05）和微生物 N 更低（P<0.05）。72 小时后，S 中乙酸比例较低（P<0.001），丙酸比例较高（P<0.05），与 8 小时孵育后 F 或 H 相比，乙酸：丙酸比例较低（P<0.001）。
PPC 中的 CT 减少了体外蛋白质降解，但对整体瘤胃发酵影响很小，干草或青贮保存 PPC 对 CT 调节瘤胃发酵的效果影响很小。© 2020 加拿大女王陛下以其名义拥有的版权。《食品科学杂志》© 2020 化学学会。
