Abstract This study aimed to evaluate the associative effect of monensin and tannins on intake, feeding behaviour, digestibility, rumen kinetics, microbial protein synthesis and nitrogen balance. In a 2 × 4 factorial arrangement, 8 rumen cannulated Nellore cows were distributed in 2 contemporary 4 × 4 Latin squares and received 8 diets that differed in the level of tannins (0.00, 0.75, 1.50 and 2.25% DM) and presence of monensin. Monensin was daily administered to each cow in one square (about 32 mg/kg DM). No interaction between monensin and tannins was observed (p > .05). Tannins linearly reduced feed intake, but linearly increased daily eating time (p < .05), although these did not alter the number of meals. Monensin increased CP digestibility by 6% (p = .0387) while tannins linearly reduced digestibility of DM, CP, OM and TDN, whereas the reduction was quadratic for ADF and NDF. Tannins linearly reduced the rumen disappearance rate by linearly reducing both passage and digestion rates. Tannins also linearly reduced urinary urea, though neither additive affected microbial protein synthesis. Monensin reduced the proportion of N excreted in faeces, whereas tannins linearly increased faecal N and linearly reduced both urinary and retained N. Monensin and tannins have shown independent effects on feeding behaviour, feed intake, digestive parameters, microbial protein synthesis and N balance, but they did not improve nutrient usage, although monensin alone has shown to have potential to promote N utilisation. Tannins may play an important role in reducing the excretion of N in urine. Highlights Tannins reduce the efficiency of nutrient usage in cattle. Tannins change the pathway of the excretion of the feeding nitrogen. The emission of N2O from the urine may be reduced by the use of tannins in cattle feeding.

中文翻译：

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单宁酸和莫能菌素对内洛尔奶牛采食行为、采食量、消化参数和微生物效率的影响

摘要 本研究旨在评估莫能菌素和单宁对采食量、摄食行为、消化率、瘤胃动力学、微生物蛋白质合成和氮平衡的相关影响。在 2 × 4 阶乘排列中，8 头瘤胃插管 Nellore 奶牛分布在 2 个当代 4 × 4 拉丁方格中，并接受 8 种不同单宁水平（0.00、0.75、1.50 和 2.25% DM）和莫能菌素的日粮。莫能菌素每天以一个正方形（约 32 mg/kg DM）施用于每头奶牛。没有观察到莫能菌素和单宁之间的相互作用（p > .05）。单宁线性减少采食量，但线性增加每日进食时间（p < .05），尽管这些并没有改变进餐次数。莫能菌素将 CP 消化率提高了 6% (p = .0387)，而单宁线性降低了 DM、CP、OM 和 TDN 的消化率，而 ADF 和 NDF 的减少是二次的。单宁通过线性降低通过率和消化率来线性降低瘤胃消失率。单宁还线性减少尿尿素，尽管这两种添加剂都不影响微生物蛋白质的合成。莫能菌素减少粪便中排泄的氮的比例，而单宁线性增加粪便 N 并线性减少尿和保留的 N。莫能菌素和单宁对摄食行为、采食量、消化参数、微生物蛋白质合成和 N 平衡显示出独立的影响，但尽管莫能菌素本身已显示具有促进氮利用的潜力，但它们并没有改善养分的使用。单宁可能在减少尿液中氮的排泄方面发挥重要作用。亮点 单宁会降低牛的营养利用效率。单宁改变了供给氮的排泄途径。在牛饲养中使用单宁可以减少尿液中 N2O 的排放。