Institute of Animal Science, University of Bonn, Bonn, Germany.
Institute of Animal Science, University of Hohenheim, Stuttgart, Germany.
J Anim Physiol Anim Nutr (Berl). 2022 Jul;106(4):752-771. doi: 10.1111/jpn.13676. Epub 2021 Dec 28.
Rumen microorganisms turn small N-containing compounds into amino acids (AA) and contribute considerably to the supply of AA absorbed from the small intestine. Previous studies summarized the literature on microbial AA patterns, most recently in 2017 (Sok et al. Journal of Dairy Science, 100, 5241-5249). The present study intended to identify the microbial AA pattern typical when feeding Central European diets and a maximum proportion of concentrate (PCO; dry matter (DM) basis) of 0.60. Data sets were created from the literature for liquid (LAB)- and particle (PAB)-associated bacteria, total bacteria and protozoa, including 16, 9, 27 and 8 studies and 36, 21, 60 and 18 diets respectively. Because the only differences detected between LAB and PAB were slightly higher Phe and lower Thr percentages in PAB (p < 0.05), results for bacteria were pooled. A further data set evaluated AA-N (AAN) as a proportion of total N in microbial fractions and a final data set estimated protozoal contributions to total microbial N (TMN) flow to the duodenum, which were used to calculate weighted TMN AA patterns. Protozoa showed higher Lys, Asp, Glu, Ile and Phe and lower Ala, Arg, Gly, Met, Ser, Thr and Val proportions than bacteria (p < 0.05). The AAN percentage of total N in bacteria and protozoa showed large, unexplained variations, averaging 79.0% and 70.6% (p > 0.05) respectively. Estimation of protozoal contribution to TMN resulted in a cattle-specific mixed model including PCO and DM intake (DMI) per unit of metabolic body size (kg ) as fixed effects (RMSE = 3.77). With moderate PCO and DMI between 80 and 180 g/kg , which corresponds to a DMI of approximately 10 to 25 kg in a cow with 650 kg body weight, protozoal contribution ranged between 9% and 26% of TMN. Within this range, the estimated protozoal contribution to TMN resulted in minor effects on the total microbial AA pattern.
瘤胃微生物将含氮的小分子化合物转化为氨基酸（AA），并为从小肠吸收的 AA 提供了重要的来源。之前的研究综述了微生物 AA 模式的文献，最近一次是在 2017 年（Sok 等人，《乳业科学杂志》，100，5241-5249）。本研究旨在确定在饲喂中欧日粮和最大 0.60 浓缩物比例（干物质（DM）基础）时的微生物 AA 模式。文献中的数据分别用于液体（LAB）和颗粒（PAB）相关细菌、总细菌和原生动物，包括 16、9、27 和 8 项研究和 36、21、60 和 18 种日粮。由于在 LAB 和 PAB 之间仅检测到苯丙氨酸（Phe）百分比稍高，而苏氨酸（Thr）百分比稍低（p<0.05），因此对细菌数据进行了汇总。进一步的数据集评估了微生物 AA-N（AAN）作为微生物分数中总氮（N）的比例，以及最后一个数据集估计了原生动物对总微生物 N（TMN）向十二指肠的流量的贡献，这两个数据集用于计算加权 TMN AA 模式。原生动物的赖氨酸（Lys）、天冬氨酸（Asp）、谷氨酸（Glu）、异亮氨酸（Ile）和苯丙氨酸（Phe）比例高于细菌，而丙氨酸（Ala）、精氨酸（Arg）、甘氨酸（Gly）、蛋氨酸（Met）、丝氨酸（Ser）、苏氨酸（Thr）和缬氨酸（Val）比例低于细菌（p<0.05）。细菌和原生动物中总 N 的 AAN 百分比存在较大的、未解释的变化，平均分别为 79.0%和 70.6%（p>0.05）。对 TMN 中原生动物贡献的估计导致了一个牛特有的混合模型，包括浓缩物（PCO）和代谢体尺（kg）每单位的采食量（DMI）作为固定效应（均方根误差（RMSE）=3.77）。在 80 到 180g/kg 之间的中等 PCO 和 DMI 下，这相当于体重为 650kg 的奶牛的 DMI 约为 10 到 25kg，原生动物的贡献范围在 TMN 的 9%到 26%之间。在这个范围内，估计的原生动物对 TMN 的贡献对总微生物 AA 模式的影响较小。
