Five in vitro experiments were conducted with the following objectives: 1) To evaluate the ruminal fermentation of three different single ingredients: corn, glycerin, and starch (Exp. 1 and 2); 2) To assess effects of partially replacing corn with glycerin in beef cattle diets on ruminal fermentation pattern (Exp. 3 and 4); and 3) To evaluate the effects of glycerin inclusion on the extension of ruminal DM digestibility of feeds with high (orchard hay) and low (corn) fiber content (Exp. 5). For Exp. 1 and 2, two in vitro systems (24-bottle Ankom^RF and 20-serum bottles) were used in four consecutive fermentation batches to evaluate gas production (GP), fermentation profiles, enteric methane (CH₄), and carbon dioxide (CO₂) of corn, glycerin, and starch. The 24 h total GP, acetate concentration, and acetate: propionate ratio decreased only when glycerin was added to the diet (P < 0.01). The 48-h total GP and metabolizable energy were greatest for corn (P < 0.01), and similar between glycerin and starch. The starch treatment had the lowest total volatile fatty acids concentration (P = 0.01). Glycerin had greatest CH₄ production, lag time, and maximum gas volume of the first pool (P < 0.05). However, the maximum gas volume of the second pool was greatest for corn (P < 0.05), and similar between glycerin and starch. The starch treatment had the greatest specific rates of digestion for first and second pools (P < 0.05). Production of CO₂ (mL/g) was greater for corn (P < 0.01), but similar for glycerin and starch. For Exp. 3 and 4, the same systems were used to evaluate four different levels of glycerin [0, 100, 200, and 300 g/kg of dry matter (DM)] replacing corn in beef cattle finishing diets. Glycerin levels did not affect 24 and 48 h total GP, CH₄, and CO₂ (P > 0.05). The inclusion of glycerin linearly decreased acetate concentration (P = 0.03) and acetate: propionate ratio (P = 0.04). For Exp. 5, two Daisy^II incubators were used to evaluate the in vitro dry matter digestibility (IVDMD) of the following treatments: orchard hay; corn; orchard hay + glycerin; and corn + glycerin. Glycerin inclusion decreased orchard hay IVDMD (P < 0.01) but did not affect corn IVDMD (P > 0.05). We concluded that, under these experimental conditions, glycerin has similar energy efficiency when used in replacement of corn and included at up to 300 g/kg in beef cattle diets.

进行了五个体外实验，其目的如下：1）评价三种不同单一成分的瘤胃发酵：玉米，甘油和淀粉（实验1和2）；2）评估肉牛日粮中用甘油部分替代玉米对瘤胃发酵模式的影响（实验3和4）；3）评估甘油含量对高（果园干草）和低（玉米）纤维饲料的瘤胃DM消化率的扩展的影响（实验5）。对于Exp。1和2，两个体外系统（24瓶Ankom ^RF和20个血清瓶）用于四个连续的发酵批次，以评估玉米，甘油和淀粉的产气量（GP），发酵曲线，肠甲烷（CH ₄）和二氧化碳（CO ₂）。仅当在饮食中添加甘油时，24小时的总GP，乙酸盐浓度和乙酸盐：丙酸盐比率才降低（P <0.01）。玉米的48小时总GP和代谢能最大（P <0.01），甘油和淀粉之间相似。淀粉处理的总挥发性脂肪酸浓度最低（P = 0.01）。甘油具有最大的CH ₄产生量，滞后时间和第一个池的最大气体量（P<0.05）。但是，第二个库的最大气体量对玉米而言最大（P <0.05），而甘油和淀粉之间的相似。淀粉处理对第一池和第二池的消化率最高（P <0.05）。玉米的CO ₂产量（mL / g）更高（P <0.01），而甘油和淀粉的产量相似。对于Exp。参照图3和图4，使用相同的系统评估四种不同水平的甘油[0、100、200和300 g / kg干物质（DM）]代替肉牛精饲料中的玉米。甘油水平不影响24、48小时总GP，CH ₄和CO ₂（P> 0.05）。包含甘油会线性降低乙酸盐浓度（P = 0.03）和乙酸盐：丙酸酯比例（P = 0.04）。对于Exp。如图5所示，使用两个Daisy ^II培养箱评估以下处理的体外干物质消化率（IVDMD）：玉米; 果园干草+甘油；和玉米+甘油。甘油的加入降低了果园干草的IVDMD（P <0.01），但不影响玉米IVDMD（P > 0.05）。我们得出的结论是，在这些实验条件下，当用于替代玉米时，甘油具有相似的能量效率，并且在肉牛日粮中的甘油含量高达300 g / kg。