Plant secondary metabolites (PSM) such as condensed tannins, hydrolysable tannins, saponins and essential oils purportedly impact rumen fermentation at low inclusion rates in beef cattle diets. Twelve steers (347 ± 23 kg BW) of British and continental influence were allocated to 1 of 4 replicated 3 x 3 Latin squares. Latin squares each had 14 d periods (10 d adaptation and 4 d for sample collection). All cattle were fed ground warm-season hay (89.5% DM, 92.8% OM, 65.9% NDF, 43.6% ADF, 6.70% CP) at 1.5% of BW (DM-basis) and supplemented with soybean meal at 0.18% of BW (DM-basis) once daily. Treatments consisted of a blend of tannins, saponins and essential oils provided at 0% (Control), 0.1% (Low) and 0.3% (High) of hay offering. Treatments were mixed with daily soybean meal allotment and provided before feeding of hay. Urine and feces were completely collected from d 11 through 14 at 0730 h and daily amounts of urine and feces produced were measured gravimetrically. Measures of gaseous exchange were determined via indirect calorimetry on d 13 and 14. Open-circuit respiration calorimeters (91.4 × 91.4 × 191.2 cm) were used to collect respired gas and ruminal methane production. Total oxygen consumption and production of carbon dioxide and methane were calculated from the difference in concentration of oxygen, carbon dioxide, and methane from air exhausted from each calorimeter and concentration of oxygen, carbon dioxide, and methane in ambient air and multiplied by amounts of air flowing from each calorimeter standardized for temperature, pressure, and humidity. Data were analyzed for a Latin square using the MIXED procedure of SAS with fixed effect of treatment, period and square and random effect of steer. Linear and quadratic contrast coefficients were assigned using PROC IML for uneven spacing of treatments. Significance was declared when P ≤ 0.05. Per experimental design, forage N and OM intake did not differ (P ≥ 0.77). Apparent total tract digestion of OM, NDF and ADF did not differ (P ≥ 0.66) among treatments. Fecal nitrogen excretion, and the percentage of N excreted in feces increased linearly (P = 0.01). N balance tended (P = 0.08) to decrease linearly with increasing PSM supplemented. Methane (L/kg DMI) was not affected (P = 0.28) by treatments. Methane, GE, DE, and ME (mcal/kg DMI) was unaffected (P = 0.19) by treatment. Under the conditions of this experiment, a blend of PSM had little effect on rumen fermentation or energy metabolism in beef steers.

中文翻译：

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145 植物次生代谢混合物对食用劣质暖季牧草的肉牛能量代谢和营养平衡的影响

据称，肉牛日粮中低含量的植物次生代谢物（PSM），例如缩合单宁、可水解单宁、皂苷和精油，会影响瘤胃发酵。英国和大陆影响的 12 头公牛（体重 347 ± 23 公斤）被分配到 4 个复制的 3 x 3 拉丁方格中的 1 个。每个拉丁方有 14 天的周期（10 天的适应和 4 天的样本收集）。所有牛均以 BW 的 1.5%（以 DM 为基础）饲喂磨碎的暖季干草（89.5% DM、92.8% OM、65.9% NDF、43.6% ADF、6.70% CP），并补充 BW 0.18% 的豆粕（DM 基础）每天一次。处理方法包括单宁、皂苷和精油的混合物，其含量分别为干草的 0%（对照）、0.1%（低）和 0.3%（高）。处理剂与每日分配的豆粕混合并在饲喂干草之前提供。从第11天到第14天0730小时完全收集尿液和粪便，并通过重量分析法测量每日产生的尿液和粪便量。在第 13 和 14 天通过间接量热法测定气体交换的测量结果。使用开路呼吸量热计 (91.4 × 91.4 × 191.2 cm) 收集呼吸气体和瘤胃甲烷产量。总耗氧量以及二氧化碳和甲烷的产生量是通过从每个量热计排出的空气中的氧气、二氧化碳和甲烷的浓度差与周围空气中的氧气、二氧化碳和甲烷的浓度差乘以空气量来计算的。来自每个标准化温度、压力和湿度的热量计。使用 SAS 的 MIXED 程序对拉丁方数据进行分析，其中包含处理的固定效应、周期和平方以及转向的随机效应。对于不均匀的处理间距，使用 PROC IML 分配线性和二次对比系数。当 P ≤ 0.05 时声明显着性。根据实验设计，饲料 N 和 OM 摄入量没有差异 (P ≥ 0.77)。OM、NDF 和 ADF 的表观全消化道消化在处理之间没有差异 (P ≥ 0.66)。粪便氮排泄量和粪便中氮排泄百分比线性增加（P = 0.01）。随着 PSM 补充量的增加，N 平衡趋于线性下降 (P = 0.08)。甲烷（L/kg DMI）不受处理影响（P = 0.28）。甲烷、GE、DE 和 ME (mcal/kg DMI) 未受处理影响 (P = 0.19)。在本实验条件下，PSM混合物对肉牛的瘤胃发酵或能量代谢几乎没有影响。