饮食营养操作(例如蛋白质部分)可以降低反刍动物的环境足迹,特别是活性氮(N)。本研究调查了日粮可溶性蛋白(SP)水平降低的粗蛋白质(CP)对肠氮吸收的影响。后肠氮代谢,粪便微生物群和代谢物,以及它们与N代谢表型的联系。32只雄性胡羊,年龄为6个月,初始体重为40.37±1.18公斤,被随机分配到四个饮食组。控制饮食(CON),符合NRC标准,以干物质为基础保持16.7%的CP含量。相反,实验饮食(LPA,LPB,和LPC)与CON相比,CP降低了10%,伴随着SP调整到21.2%,25.9%,和29.4%的CP,分别。我们的结果表明,低蛋白饮食导致血浆肌酐浓度显着降低,氨,尿素N,粪便总短链脂肪酸(SCFA)(P<0.05)。值得注意的是,与LPA相比,LPB和LPC表现出增加的总SCFA和丙酸浓度(P<0.05)。与能量代谢和氨基酸(AA)生物合成途径相关的粪便微生物群中Prevotella属的富集明显,低蛋白饮食中的SP水平约为25%至30%。此外,LPB和LPC日粮显示粪便NH4-N和NO2--N含量以及脲酶活性降低,与CON相比(P<0.05)。同时,粪便谷氨酸脱氢酶基因(gdh)的减少,亚硝酸还原酶基因(nirS),观察到一氧化氮还原酶基因(norB)丰度(P<0.05),指向源头反应性氮产量的潜在减少。意义重大,小肠中AA和肽转运蛋白的mRNA丰度上调(十二指肠,空肠,和回肠)和血浆AA浓度升高(例如精氨酸,蛋氨酸,天冬氨酸,谷氨酸,等。)强调了氮吸收和氮效率的增强。总之,CP减少10%,再加上大约25%到30%的SP水平,证明了通过粪便Prevotella富集减少反应性N排放并提高肠道能量和N利用效率的潜力。
Dietary nutrient manipulation (e.g. protein fractions) could lower the environmental footprints of ruminants, especially reactive nitrogen (N). This study investigated the impacts of dietary soluble protein (SP) levels with decreased crude protein (CP) on intestinal N absorption, hindgut N metabolism, fecal microbiota and metabolites, and their linkage with N metabolism phenotype. Thirty-two male Hu sheep, with an age of six months and an initial BW of 40.37 ± 1.18 kg, were randomly assigned to four dietary groups. The control diet (CON), aligning with NRC standards, maintained a CP content of 16.7% on a dry matter basis. Conversely, the experimental diets (LPA, LPB, and LPC) featured a 10% reduction in CP compared with CON, accompanied by SP adjustments to 21.2%, 25.9%, and 29.4% of CP, respectively. Our results showed that low-protein diets led to significant reductions in the concentrations of plasma creatinine, ammonia, urea N, and fecal total short-chain fatty acids (SCFA) (P < 0.05). Notably, LPB and LPC exhibited increased total SCFA and propionate concentrations compared with LPA (P < 0.05). The enrichment of the Prevotella genus in fecal microbiota associated with energy metabolism and amino acid (AA) biosynthesis pathways was evident with SP levels in low-protein diets of approximately 25% to 30%. Moreover, LPB and LPC diets demonstrated a decrease in fecal NH 4 + -N and NO 2 - -N contents as well as urease activity, compared with CON (P < 0.05). Concomitantly, reductions in fecal glutamic acid dehydrogenase gene (gdh), nitrite reductase gene (nirS), and nitric oxide reductase gene (norB) abundances were observed (P < 0.05), pointing towards a potential reduction in reactive N production at the source. Of significance, the up-regulation of mRNA abundance of AA and peptide transporters in the small intestine (duodenum, jejunum, and ileum) and the elevated concentration of plasma AA (e.g. arginine, methionine, aspartate, glutamate, etc.) underscored the enhancement of N absorption and N efficiency. In summary, a 10% reduction in CP, coupled with an SP level of approximately 25% to 30%, demonstrated the potential to curtail reactive N emissions through fecal Prevotella enrichment and improve intestinal energy and N utilization efficiency.