Xue Fuguang, Nan Xuemei, Sun Fuyu, Pan Xiaohua, Guo Yuming, Jiang Linshu, Xiong Benhai
State Key Laboratory of Animal Nutrition, Institute of Animal Science, Chinese Academy of Agricultural Sciences, Beijing, China.
State Key Laboratory of Animal Nutrition, College of Animal Science, China Agricultural University, Beijing, China.
AMB Express. 2018 Oct 3;8(1):159. doi: 10.1186/s13568-018-0680-6.
Ruminal thiamine deficiencies occur when dairy cows are overfed with high-concentrate diet, and thiamine supplementation has been proved to attenuate high-concentrate diet induced SARA. However, there is limited knowledge of the relationship between thiamine supplementation in high-concentrate diets and ruminal fungi. In order to investigate the impacts of thiamine supplementation on ruminal fungi, twelve Chinese Holstein dairy cows were randomly assigned into three treatments: control diet (CON; 20% starch, dry matter basis), high-concentrate diet (HC; 33.2% starch, dry matter basis) and high-concentrate diet supplemented with 180 mg thiamine/kg dry matter intake. Dry matter intake and milk production were recorded during the experimental periods. On day 21, rumen fluid samples were collected at 3 h postfeeding and ruminal pH, thiamine concentration and volatile fatty acids were measured. Metagenome sequencing method was conducted to detect ruminal fungi composition. Feeding HC significantly decreased dry matter intake, milk production, ruminal pH, ruminal acetate and thiamine concentration, however, significantly increased propionate and isovalerate (P < 0.05). These changes were inversed by thiamine supplementation (P < 0.05). Totally, seven phyla and almost 1050 species of rumen fungi were identified across all samples in which especially, 3 genera and 10 species of strictly anaerobic fungi phylum Neocallimastigomycota was found. Principal coordinate analysis indicated that feeding HC and thiamine supplementation caused a significant inverse in ruminal fungi composition. Feeding HC significantly decreased the abundance of fungi compared with CON (P < 0.05) while thiamine supplementation significantly increased the abundance of ruminal fungi (P < 0.05). These results indicated that thiamine supplementation may effectively attenuate rumen metabolic disorder caused by HC diet through buffering the ruminal pH, shifting the rumen fermentation pattern and increasing the abundance of ruminal fungi. The findings in this study could therefore contribute to the further understanding of the mechanism of thiamine's function in dairy cows.
当奶牛过量饲喂高浓度日粮时，会出现瘤胃酸缺乏症，补充硫胺素已被证明可减轻高浓度日粮诱导的亚急性瘤胃酸中毒（SARA）。然而，关于高浓度日粮中补充硫胺素与瘤胃真菌之间的关系，人们了解有限。为了研究补充硫胺素对瘤胃真菌的影响，将12头中国荷斯坦奶牛随机分为三组处理：对照日粮（CON；淀粉含量20%，干物质基础）、高浓度日粮（HC；淀粉含量33.2%，干物质基础）和高浓度日粮补充180毫克硫胺素/千克干物质摄入量。在实验期间记录干物质摄入量和产奶量。在第21天，在喂食后三小时采集瘤胃液样本，并测量瘤胃pH值、硫胺素浓度和挥发性脂肪酸。采用宏基因组测序方法检测瘤胃真菌组成。饲喂HC显著降低了干物质摄入量、产奶量、瘤胃pH值、瘤胃乙酸盐和硫胺素浓度，但显著增加了丙酸盐和异戊酸盐（P<0.05）。这些变化通过补充硫胺素得到逆转（P<0.05）。在所有样本中总共鉴定出七个门和近1050种瘤胃真菌，其中特别发现了新美鞭菌门的3个属和10种严格厌氧真菌。主坐标分析表明，饲喂HC和补充硫胺素导致瘤胃真菌组成发生显著相反变化。与CON相比，饲喂HC显著降低了真菌丰度（P<0.05），而补充硫胺素显著增加了瘤胃真菌丰度（P<0.05）。这些结果表明，补充硫胺素可能通过缓冲瘤胃pH值、改变瘤胃发酵模式和增加瘤胃真菌丰度，有效减轻HC日粮引起的瘤胃代谢紊乱。因此，本研究的结果有助于进一步了解硫胺素在奶牛中的作用机制。
