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Abstract：
The dietary crude protein level could affect ruminal fermentation parameters and the microflora of ruminants. The present study\'s aim was to investigate the effects of different protein level diets on ruminal morphology, fermentation parameters, digestive enzyme activity, microflora and metabolites of Tibetan sheep. Ninety weaned lambs (initial weight of 15.40 ± 0.81 kg, 2 months old) were selected and randomly divided into three groups (six pens/treatment, five rams/pen). Dietary treatments were formulated with 13.03% (high protein, HP), 11.58% (moderate protein, MP) and 10.20% (low protein, LP), respectively. Compared with LP, both papillae length and papillae width were significantly promoted in HP and MP (p < 0.05). The concentrations of ammonia nitrogen, total VFAs, propionic acids and butyric acids in HP were significantly increased compared to those in MP and LP (p < 0.05). The activities of protease and α-amylase in HP were significantly greater than those of LP (p < 0.05). For the ruminal microbial community, higher proportions of phylum Prevotella 1 and Succiniclasticum and genus Rikenellaceae RC9 gut group and Ruminococcus 1 were observed in HP (p < 0.05). A total of 60 differential metabolites (DMs) (28 up, 32 down) between HP and MP; 73 DMs (55 up, 18 down) between HP and LP; and 65 DMs (49 up, 16 down) between MP and LP were identified. Furthermore, four pathways of the biosynthesis of unsaturated fatty acids, tryptophan metabolism, bile secretion and ABC transporters were significantly different (p < 0.05). The abundance of phylum Prevotella 1 was negatively associated with stearic acid and palmitic acid but positively associated with the taurine. The abundance of genus Ruminococcus 1 was negatively associated with stearic acid, oleic acid, erucic acid, Indole-3-acetamide and palmitic acid but positively associated with 6-hydroxymelatonin. In conclusion, a 13.03% CP level improved ruminal morphology, fermentation parameters and digestive enzyme activities through modulating the microbial community and regulating metabolism in Tibetan sheep.
摘要：
日粮粗蛋白水平会影响反刍动物瘤胃发酵参数和微生物区系。本研究的目的是探讨不同蛋白质水平日粮对瘤胃形态的影响,发酵参数，消化酶活性，藏绵羊的微生物区系和代谢产物。九十只断奶羔羊(初始体重15.40±0.81公斤,选择2月龄），随机分为三组（六笔/治疗，五只公羊/钢笔)。饮食治疗的配方为13.03%(高蛋白，HP),11.58%(中等蛋白质，MP)和10.20%(低蛋白，LP),分别。与LP相比,HP和MP的乳头长度和乳头宽度均显着增加（p<0.05）。氨氮的浓度,总VFA，与MP和LP相比，HP中的丙酸和丁酸显着增加（p<0.05）。HP中的蛋白酶和α-淀粉酶活性显着高于LP（p<0.05）。对于瘤胃微生物群落，在HP中观察到较高比例的Prevotella1和Suciniclasticum以及RikenellaceaeRC9肠组和Ruminococus1（p<0.05）。共有60种差异代谢物（DMs）（28种，32个向下)在HP和MP之间；73个DM(55个向上，HP和LP之间下降18个)；和65个DM(49个上升，确定了MP和LP之间的16个下降）。此外，不饱和脂肪酸生物合成的四种途径，色氨酸代谢,胆汁分泌和ABC转运体有显著差异(p<0.05)。普雷沃氏菌1门的丰度与硬脂酸和棕榈酸呈负相关，而与牛磺酸呈正相关。Ruminococcus1属的丰度与硬脂酸呈负相关，油酸,芥酸,吲哚-3-乙酰胺和棕榈酸，但与6-羟基褪黑素呈正相关。总之,13.03%CP水平改善瘤胃形态，通过调节藏绵羊的微生物群落和代谢调节来实现发酵参数和消化酶活性。
