硫胺素和硫水平对山羊人工瘤胃代谢和微生物菌群的影响

【目的】探讨在不同硫水平条件下，添加硫胺素（维生素B1）对人工瘤胃内营养物质消化代谢的影响。【方法】按2×2因子试验设计，因子一为不同的氮硫比（高硫水平，即N﹕S=5﹕1；低硫水平即N﹕S=15﹕1），因子二为不添加和添加硫胺素（0和60 mg?kg-1）进行人工瘤胃培养试验。【结果】 添加硫胺素对pH和NH3-N浓度的影响不显著；高硫水平能够抑制细菌蛋白的合成，显著提高了瘤胃培养液中原虫和细菌蛋白质的比值（P/WB）（P＜0.05）；在低硫水平下，添加硫胺素处理组TVFA的摩尔浓度和丁酸百分含量均高于不添加硫胺素组（P＜0.05），而乙酸低于不添加硫胺素组。在高硫水平下，添加硫胺素处理组与不添加组之间总挥发性脂肪酸和单一脂肪酸的摩尔浓度无显著差异（P＞0.05）。高硫水平能够降低培养液中硫胺素的总量，而添加的硫胺素则增加了培养液中硫胺素的总量；高硫水平可以降低乳酸的浓度；同一氮硫水平下，添加硫胺素处理组的牛链球菌的相对数量比非添加组分别降低了5.90%（P＜0.05）和2.05%（P＜0.01）；添加不同水平的硫和硫胺素对溶纤维丁酸弧菌的相对数量的影响不显著（P＞0.05）。【结论】人工瘤胃中硫水平对瘤胃发酵有一定影响，高硫水平可显著降低培养液中的乳酸浓度，提高原虫蛋白质的合成量，而抑制细菌蛋白质的合成；无机硫和硫胺素在降低瘤胃内乳酸浓度和缓解瘤胃酸中毒中起重要作用，并且二者对乳酸浓度的影响存在互作效应。添加不同水平的硫和硫胺素能够降低瘤胃液中牛链球菌的相对数量，对瘤胃液中溶纤维丁酸弧菌的相对数量的影响不显著（P＜0.05）。

Effect of Thiamin on the Rumen Fermentation and Microbial Community of the Substrates in Rusitec

【Objective】An experiment was conducted to determine the effect of thiamin on rumen fermentation and microbial community under different nitrogen levels to sulfur ratio in Rusitec.【Method】 A 2×2 two factorial design of an experiment was adopted: one factor was different nitrogen levels to sulphur ratios(5﹕1,15﹕1),the other was different substrates with and without adding thiamin(0 and 60 mg·kg-1).【Result】 The results showed that there was no significant effect on pH and ammonia concentration in the substrates.The high sulfur level restrained the synthesis of bacterial protein and significantly decreased the ratio of protozoal protein and bacterial protein(P<0.05).There was no effect on the concentrations of acetate,propionate and the acetate/propionate ratio(P<0.05).The low sulfur level increased the concentration of butyrate,total VFAs and the proportion of butyrate,and the high S level reduced the total concentration of thiamin while the total thiamin was increased by adding thiamin.There was an obvious consequence that the high sulfur substrate declined the concentration of the lactate in Rusitec.Compared to the without adding thiamin group,the relative number of Strepococcus bovis in substrates with adding thiamin decreased by 5.90%(P< 0.05) and 2.05%(P<0.01) under the same nitrogen/sulfur ratios,and there was no significant effect on the number of Butyrivibrio fibrisovens.【Conclusion】 It was concluded that rumen fermentation was response to sulfur level in Rusitec,higher levels of sulfur in sulfur substrate could decline the concentration of the lactate and bacterial protein while protozal protein dropped in Rusitec.It was found that sulfur and thiamin play an important role in suppressing of subacute rumen acidosis(SARA).Adding thiamin in Rusitec resulted in the decrease of the relative number of S.bovis in substrates,but had no significant effect on the number of B.fibrisovens.