State Key Laboratory of Animal Nutrition, Institute of Animal Science, Chinese Academy of Agricultural Sciences, Beijing, China.
Beijing Key Laboratory for Dairy Cow Nutrition, Beijing University of Agriculture, Beijing, China.
Appl Environ Microbiol. 2021 Jan 4;87(2). doi: 10.1128/AEM.01908-20.
Rumen-protected glucose (RPG) plays an important role in alleviating the negative energy balance of dairy cows. This study used a combination of rumen microbes 16S and metabolomics to elucidate the changes of rumen microbial composition and rumen metabolites of different doses of RPG's rumen degradation part in early-lactation dairy cows. Twenty-four multiparous Holstein cows in early lactation were randomly allocated to control (CON), low-RPG (LRPG), medium-RPG (MRPG), or high-RPG (HRPG) groups in a randomized block design. The cows were fed a basal total mixed ration diet with 0, 200, 350, and 500 g of RPG per cow per day, respectively. Rumen fluid samples were analyzed using Illumina MiSeq sequencing and ultrahigh-performance liquid chromatography coupled to quadrupole time-of-flight mass spectrometry. MRPG supplementation increased bacterial richness and diversity, including increasing the relative abundance of cellulolytic bacteria, such as , , , and MRPG significantly increased the concentrations of acetate, propionate, butyrate, and total volatile fatty acid in the rumen. Ruminal fluid metabolomics analysis showed that RPG supplementation could significantly regulate the synthesis of amino acids digested by protozoa in the rumen. Correlation analysis of the ruminal microbiome and metabolome revealed some potential relationships between major bacterial abundance and metabolite concentrations. Our analysis found that RPG supplementation of different doses can change the diversity of microorganisms in the rumen and affect the rumen fermentation pattern and microbial metabolism and that a daily supplement of 350 g of RPG might be the ideal dose. Dairy cows in early lactation are prone to a negative energy balance because their dry matter intake cannot meet the energy requirements of lactation. Rumen-protected glucose is used as an effective feed additive to alleviate the negative energy balance of dairy cows in early lactation. However, one thing that is overlooked is that people often think that rumen-protected glucose is not degraded in the rumen, thus ignoring its impact on the microorganisms in the rumen environment. Our investigation and previous experiments have found that rumen-protected glucose is partially degraded in the rumen. However, there are few reports on this subject. Therefore, we conducted research on this problem and found that rumen-protected glucose supplementation at 350 g/day can promote the development and metabolism of rumen flora. This provides a theoretical basis for the extensive application of rumen bypass glucose at a later stage.
瘤胃保护葡萄糖（RPG）在缓解奶牛能量负平衡方面发挥着重要作用。本研究采用瘤胃微生物 16S 和代谢组学相结合的方法，阐明了不同剂量 RPG 瘤胃降解部分对泌乳早期奶牛瘤胃微生物组成和瘤胃代谢物的变化。将 24 头泌乳早期的经产荷斯坦奶牛随机分为对照组（CON）、低 RPG（LRPG）、中 RPG（MRPG）和高 RPG（HRPG）组，采用随机区组设计。奶牛饲喂基础全混合日粮，每天每头牛分别饲喂 0、200、350 和 500 g RPG。采用 Illumina MiSeq 测序和超高效液相色谱-四极杆飞行时间质谱联用技术对瘤胃液样品进行分析。MRPG 补充剂增加了细菌的丰富度和多样性，包括增加了纤维素分解菌的相对丰度，如 、 、 和 。MRPG 显著增加了瘤胃中乙酸、丙酸、丁酸和总挥发性脂肪酸的浓度。瘤胃液代谢组学分析表明，RPG 补充剂可以显著调节瘤胃中被原生动物消化的氨基酸的合成。瘤胃微生物组和代谢组的相关性分析显示了主要细菌丰度和代谢物浓度之间的一些潜在关系。我们的分析发现，不同剂量的 RPG 补充剂可以改变瘤胃微生物的多样性，影响瘤胃发酵模式和微生物代谢，每天补充 350 g RPG 可能是理想的剂量。泌乳早期的奶牛由于干物质摄入不能满足泌乳的能量需求，容易出现能量负平衡。瘤胃保护葡萄糖作为一种有效的饲料添加剂，可缓解泌乳早期奶牛的能量负平衡。然而，人们往往忽视了一点，即人们认为瘤胃保护葡萄糖在瘤胃中不会被降解，从而忽略了它对瘤胃环境中微生物的影响。我们的调查和以前的实验发现，瘤胃保护葡萄糖在瘤胃中部分降解。然而，关于这个主题的报道很少。因此，我们对这个问题进行了研究，发现每天补充 350 g 瘤胃保护葡萄糖可以促进瘤胃菌群的发育和代谢。这为后期广泛应用瘤胃旁路葡萄糖提供了理论依据。
