Abstract

Date kernels (DK) are cheap by-products rich in energy and phenolic compounds. It can be used as an alternative to the conventional sources of energy in ruminant diets while reducing methane (CH₄) production. Using a semi-automated gas production (GP) system, the initial pH of buffered rumen liquor was adjusted to 5.5 and 6.8. Five experimental diets were evaluated, control (0% DK), and DK₂₅, DK₅₀, DK_75, and DK₁₀₀ presented 25, 50, 75, and 100% replacement of maize by DK, respectively. Of the 16 phenolic compounds detected in DK, protocatechuic, p-hydroxybenzoic and catechin were the most abundant. At pH 6.8, the control diet recorded higher (p < 0.05) GP values throughout the first 12 h incubation than all other DK diets, while at 5.5 pH, DK₅₀ displayed the highest (p < 0.05) GP at 3 and 6 h compared to all other diets. At either pH conditions, all DK diets reduced (p < 0.05) CH₄ compared to the control without affecting protozoal counts. At 5.5 pH, DK diets showed enhanced (p < 0.05) nutrients degradability compared to control. DK modified (P < 0.05) the fermentation patterns toward more propionate than the control under either pH conditions. Substitution of maize by 50% DK was highly recommended in ruminant diets.

摘要

枣仁 (DK) 是富含能量和酚类化合物的廉价副产品。它可以用作反刍动物饮食中传统能源的替代品，同时减少甲烷 (CH ₄ ) 的产生。使用半自动产气 (GP) 系统，将缓冲瘤胃液的初始 pH 值调节至 5.5 和 6.8。评估了五种实验日粮，对照（0% DK）和 DK ₂₅、DK ₅₀、DK ₇₅和 DK ₁₀₀分别提供了 25%、50%、75% 和 100% 的 DK 替代玉米。在 DK 中检测到的 16 种酚类化合物中，原儿茶酸、对羟基苯甲酸和儿茶素含量最高。在 pH 6.8 时，对照饮食记录更高（p < 0.05) 在第一个 12 小时孵育期间的 GP 值高于所有其他 DK 饮食，而在 5.5 pH 时，与所有其他饮食相比，DK ₅₀在 3 和 6 小时显示最高 ( p  < 0.05) GP。在任一 pH 条件下，与对照相比，所有 DK 饮食都减少了 ( p  < 0.05) CH _{4 ，而不影响原生动物计数。} 在 5.5 pH 值时，与对照相比，DK 日粮显示出增强的 ( p < 0.05) 营养素降解能力。DK 修改 (P < 0.05) 发酵模式比任一 pH 条件下的控制更丙酸。强烈建议在反刍动物日粮中用 50% DK 替代玉米。