Xue Fuguang, Nan Xuemei, Li Yunlei, Pan Xiaohua, Guo Yuming, Jiang Linshu, Xiong Benhai
State Key Laboratory of Animal Nutrition, Institute of Animal Science, Chinese Academy of Agricultural Sciences, Beijing, 100193, China.
State Key Laboratory of Animal Nutrition, College of Animal Sciences, China Agricultural University, Beijing, 100193, China.
BMC Vet Res. 2019 Jan 3;15(1):7. doi: 10.1186/s12917-018-1745-0.
Overfeeding of high-concentrate diet (HC) frequently leads to subacute ruminal acidosis (SARA) in modern dairy cows' production. Thiamine supplementation has been confirmed to attenuate HC induced SARA by increasing ruminal pH and ratio of acetate to propionate, and decreasing rumen lactate, biogenic amines and lipopolysaccharide (LPS). The effects of thiamine supplementation in HC on rumen bacteria and fungi profile had been detected in our previous studies, however, effects of thiamine supplementation in HC on rumen non-methanogen archaea is still unclear. The objective of the present study was therefore to investigate the effects of thiamine supplementation on ruminal archaea, especially non-methanogens in HC induced SARA cows.
HC feeding significantly decreased dry matter intake, milk production, milk fat content, ruminal pH and the concentrations of thiamine and acetate in rumen fluid compared with control diet (CON) (P < 0.05), while the concentrations of propionate and ammonia-nitrogen (NH-N) were significantly increased compared with CON (P < 0.05). These changes caused by HC were inversed by thiamine supplementation (P < 0.05). The taxonomy results showed that ruminal archaea ranged from 0.37 to 0.47% of the whole microbiota. Four characterized phyla, a number of Candidatus archaea and almost 660 species were identified in the present study. In which Euryarchaeota occupied the largest proportion of the whole archaea. Furthermore, thiamine supplementation treatment significantly increased the relative abundance of non-methanogens compared with CON and HC treatments. Thaumarchaeota was increased in HC compared with CON. Thiamine supplementation significantly increased Crenarchaeota, Nanoarchaeota and the Candidatus phyla, however decreased Thaumarchaeota compared with HC treatment.
HC feeding significantly decreased ruminal pH and increased the content of NH-N which led to N loss and the increase of the relative abundance of Thaumarchaeota. Thiamine supplementation increased ruminal pH, improved the activity of ammonia utilizing bacteria, and decreased Thaumarchaeota abundance to reduce the ruminal NH content and finally reduced N loss. Overall, these findings contributed to the understanding of thiamine's function in dairy cows and provided new strategies to improve dairy cows' health under high-concentrate feeding regime.
在现代奶牛生产中，高浓度日粮（HC）过度饲喂常导致亚急性瘤胃酸中毒（SARA）。已证实补充硫胺素可通过提高瘤胃pH值、乙酸与丙酸比例，降低瘤胃乳酸、生物胺和脂多糖（LPS）来减轻HC诱导的SARA。在我们之前的研究中已检测到HC中补充硫胺素对瘤胃细菌和真菌谱的影响，然而，HC中补充硫胺素对瘤胃非产甲烷古菌的影响仍不清楚。因此，本研究的目的是探讨补充硫胺素对瘤胃古菌，特别是对HC诱导SARA奶牛瘤胃非产甲烷古菌的影响。
与对照日粮（CON）相比，HC饲喂显著降低了干物质摄入量、产奶量、乳脂肪含量、瘤胃pH值以及瘤胃液中硫胺素和乙酸盐的浓度（P < 0.05），而丙酸盐和氨氮（NH-N）的浓度与CON相比显著增加（P < 0.05）。补充硫胺素可逆转由HC引起的这些变化（P < 0.05）。分类学结果表明，瘤胃古菌占整个微生物群的0.37%至0.47%。在本研究中鉴定出了四个特征门、一些候选古菌和近660个物种。其中广古菌门在整个古菌中占比最大。此外，与CON和HC处理相比，补充硫胺素处理显著增加了非产甲烷古菌的相对丰度。与CON相比，HC中泉古菌门增加。与HC处理相比，补充硫胺素显著增加了奇古菌门、纳古菌门和候选门，但降低了泉古菌门。
HC饲喂显著降低瘤胃pH值，增加NH-N含量，导致氮损失和泉古菌门相对丰度增加。补充硫胺素可提高瘤胃pH值，改善氨利用细菌的活性，降低泉古菌门丰度，以降低瘤胃NH含量，最终减少氮损失。总体而言，这些发现有助于理解硫胺素在奶牛中的功能，并为在高浓度饲养模式下改善奶牛健康提供了新策略。
