One hundred and forty-four Angus x Simmental steers were allotted by body weight (BW; 363 kg), breed composition, and farm origin to a 3 x 2 factorial arrangement of 6 treatments (4 pens per treatment) to determine the effect of Mootral (garlic + citrus extract; 0.25% of the diet DM vs. 0.0%) on methane emissions, growth and carcass characteristics of feedlot cattle. During the first 84 days, cattle were fed three different forage concentrations in the diet (15, 41.5, or 68% corn silage) with or without Mootral. From day 85 to slaughter, corn silage was included at 15% of the diet DM with or without Mootral. Methane emissions were measured on day 42 to 46 and day 203 to 207. Data were analyzed using the GLIMMIX procedure of SAS. Mootral did not affect methane emissions on days 42 to 46 (P ≥ 0.47), but there was a forage effect, where steers fed the 68% corn silage emitted more methane on a g/d (P = 0.05) and a g/kg of DMI (P = 0.007) basis and tended (P = 0.07) to produce more methane on g/kg BW basis compared to steers fed the 15% corn silage diet. On d 203 to 207, steers fed Mootral emitted less (P ≤ 0.03) methane on a g/d, g/kg DMI, and g/kg BW basis compared to steers not fed Mootral. There was an interaction (P = 0.03) between forage concentration and Mootral for DMI from d 0 to 84, where Mootral decreased DMI of steers fed 15% corn silage but did not affect DMI of steers fed 41.5 or 68% corn silage. There were no effects (P ≥ 0.22) of forage concentration or Mootral on BW or average daily gain at any time, or on DMI from d 84 to slaughter and overall. However, overall calculated NEm and NEg tended to be greater for steers fed Mootral (P ≤ 0.10). Intake from d 0-84 was lower and gain:feed from d 0-84 and overall was greater (P = 0.04) for steers fed 68% compared to steers fed 41.5% corn silage. Calculated NEm and NEg from day 0 to 84 and overall were greater for steers fed 68% corn silage compared to steers fed 41.5% corn silage (P ≤ 0.03). Mootral tended to decrease (P ≤ 0.09) fat thickness and yield grade. In conclusion, increasing forage concentration increased methane emissions and Mootral decreased methane production in 15% corn silage diets and tended to improve carcass leanness.

中文翻译：

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在三种不同饲料浓度的日粮中饲喂大蒜和柑橘类饲料添加剂的饲养场公牛的肠道甲烷排放、生长和胴体特征

将 144 头安格斯 x 西门塔尔公牛按照体重（体重；363 千克）、品种组成和农场来源分配到 6 个处理的 3 x 2 因子排列（每个处理 4 栏），以确定 Mootral 的效果（大蒜 + 柑橘提取物；日粮 DM 的 0.25% 与 0.0%）对饲养场牛的甲烷排放、生长和胴体特征的影响。在最初的 84 天里，牛在日粮中饲喂三种不同浓度的草料（15%、41.5% 或 68% 玉米青贮饲料），添加或不添加 Mootral。从第 85 天到屠宰，玉米青贮饲料占日粮干物质的 15%，含或不含 Mootral。在第 42 至 46 天和第 203 至 207 天测量甲烷排放量。使用 SAS 的 GLIMMIX 程序分析数据。Mootral 不会影响第 42 至 46 天的甲烷排放量 (P ≥ 0.47)，但存在饲料效应，其中饲喂 68% 玉米青贮饲料的公牛在 ag/d (P = 0.05) 和 ag/kg DMI 上排放更多甲烷(P = 0.007) 基础上，并且与饲喂 15% 玉米青贮饲料的阉牛相比，以 g/kg BW 为基础倾向于 (P = 0.07) 产生更多的甲烷。在第 203 至 207 天，与未饲喂 Mootral 的阉牛相比，以 ag/d、g/kg DMI 和 g/kg BW 计算，饲喂 Mootral 的阉牛排放的甲烷较少（P ≤ 0.03）。从第 0 天到第 84 天，草料浓度和 Mootral 的 DMI 之间存在交互作用（P = 0.03），其中 Mootral 降低了饲喂 15% 玉米青贮饲料的阉牛的 DMI，但不影响饲喂 41.5 或 68% 玉米青贮饲料的阉牛的 DMI。饲料浓度或 Mootral 对任何时间的体重或平均日增重，或从第 84 天到屠宰和总体的 DMI 没有影响 (P ≥ 0.22)。然而，总体计算得出的 NEm 和 NEg 对于饲喂 Mootral 的阉牛来说往往更大（P ≤ 0.10）。与饲喂 41.5% 玉米青贮饲料的阉牛相比，饲喂 68% 玉米青贮饲料的阉牛从第 0-84 天的采食量较低，而从第 0-84 天饲喂的饲料和总体增益较高（P = 0.04）。从第 0 天到第 84 天计算出的 NEm 和 NEg 总体而言，饲喂 68% 玉米青贮饲料的阉牛比饲喂 41.5% 玉米青贮饲料的阉牛更高（P ≤ 0.03）。Mootral 倾向于降低 (P ≤ 0.09) 脂肪厚度和产量等级。总之，增加草料浓度会增加甲烷排放量，而 Mootral 会降低 15% 玉米青贮日粮中的甲烷产量，并倾向于改善胴体瘦肉率。