Department of Animal Science, Faculty of Agriculture, Ferdowsi University of Mashhad, PO Box 91775-1163, Mashhad, Iran; Innovation Center, Ferdowsi University of Mashhad, PO Box 9177948974, Mashhad, Iran.
Department of Animal Science, Faculty of Agriculture, Ferdowsi University of Mashhad, PO Box 91775-1163, Mashhad, Iran.
J Dairy Sci. 2020 May;103(5):4327-4339. doi: 10.3168/jds.2019-17169. Epub 2020 Mar 5.
We aimed to evaluate the effects of feeding sugarcane liquid molasses (LM) with or without a commercial buffer mix (BFM) on ruminal fermentation parameters, milk fatty acid (FA) profile, and milk yield and composition in dairy cows fed high-concentrate diets (35:65 forage-to-concentrate ratio). Eight multiparous Holstein cows (4 ruminally cannulated) averaging 165 ± 12 d in milk at the beginning of the study were randomly assigned to a replicated 4 × 4 Latin square design with a 2 × 2 factorial arrangement of treatments. Each period lasted 21 d with 14 d for diet adaptation and 7 d for data and sample collection. Cows were fed the following diets: (1) no LM or BFM supplementation (CTRL), (2) LM without BFM supplementation (MOL), (3) BFM without LM supplementation (BUF), and (4) LM plus BFM supplementation (COMBO). These 4 isonitrogenous and isoenergetic diets were formulated by replacing (dry matter basis) 5% ground corn with LM, whereas BFM replaced wheat bran at 0.8% of the diet. Significant LM × BFM interactions were observed for the duration of ruminal pH below 5.8, molar proportion of propionate, acetate-to-propionate ratio, milk proportions of trans-10 18:1 and total trans FA, and concentration and yield of milk fat. Feeding MOL and BUF alone were effective on reducing the time that ruminal pH remained below 5.8 compared with the CTRL treatment, and the COMBO diet decreased it further. A similar pattern was observed for the ruminal molar proportion of propionate. The milk proportions of trans-10 18:1 and total trans FA dropped significantly with BFM or LM supplementation versus cows fed CTRL, and the COMBO diet decreased these variables further. Note, however, that these changes elicited by the COMBO diet were not in the same magnitude as those caused by MOL or BUF fed alone. The ruminal molar proportion of acetate increased with the BUF diet and that of butyrate increased in cows fed MOL, but mean ruminal pH was not affected by treatments. Diets with LM resulted in increased concentrations of short- and medium-chain FA in milk fat. The yield of 3.5% fat-corrected milk increased significantly in cows fed MOL or BUF due to the improved concentration of milk fat. A trend and a significant increase for energy-corrected milk were observed with feeding MOL or BUF, respectively. Overall, inclusion of LM and BFM appears to reduce milk trans-10 18:1 FA and total trans FA by modulating ruminal pH and volatile FA profile in cows fed high-concentrate diets.
我们旨在评估在高浓度日粮（35:65 的粗饲料与精饲料比例）中给奶牛饲喂甘蔗液态糖蜜（LM）和/或商业缓冲混合剂（BFM）对瘤胃发酵参数、乳脂肪酸（FA）谱以及牛奶产量和成分的影响。8 头泌乳中期（开始研究时平均泌乳 165±12 天）的荷斯坦奶牛被随机分配到一个重复 4×4 拉丁方设计的 2×2 因子处理安排中。每个周期持续 21 天，其中 14 天用于适应饮食，7 天用于收集数据和样本。奶牛被喂食以下日粮：（1）不添加 LM 或 BFM 作为对照（CTRL），（2）不添加 LM 但添加 BFM（MOL），（3）不添加 LM 但添加 BFM（BUF），（4）添加 LM 和 BFM（COMBO）。这些 4 种等氮和等能日粮是通过用 LM 替代 5%的粉碎玉米（干物质基础）来配制的，而 BFM 则以日粮的 0.8%替代了小麦麸皮。在瘤胃 pH 低于 5.8 的持续时间、丙酸摩尔比例、乙酸/丙酸比、反式-10 18:1 和总反式 FA 的乳比例以及乳脂肪浓度和产量方面，观察到显著的 LM×BFM 相互作用。与对照处理相比，单独饲喂 MOL 和 BUF 可有效减少瘤胃 pH 低于 5.8 的时间，而 COMBO 日粮进一步降低了该时间。丙酸的瘤胃摩尔比例也出现了类似的模式。与对照组相比，添加 BFM 或 LM 可显著降低乳中反式-10 18:1 和总反式 FA 的比例，而 COMBO 日粮则进一步降低了这些变量。然而，请注意，COMBO 日粮引起的这些变化的幅度不如单独饲喂 MOL 或 BUF 引起的变化大。随着 BUF 日粮的饲喂，乙酸的瘤胃摩尔比例增加，而 MOL 日粮的丁酸比例增加，但处理对平均瘤胃 pH 没有影响。添加 LM 会增加乳脂肪中的短链和中链 FA 浓度。由于乳脂浓度的提高，MOL 或 BUF 喂养的奶牛的 3.5%乳脂校正奶产量显著增加。饲喂 MOL 或 BUF 分别表现出能量校正奶的趋势和显著增加。总体而言，在高浓度日粮中添加 LM 和 BFM 似乎通过调节瘤胃 pH 和挥发性 FA 谱来降低奶牛乳中反式-10 18:1 FA 和总反式 FA。
