This study investigated the effects of β-alanine (β-Ala) on rumen fermentation, nutrient digestibility, nitrogen (N) metabolism, plasma biochemical parameters, and rumen bacterial communities in beef steers. Six steers with initial liveweight of 252.8 ± 5.2 kg and 3 treatments of supplementing with 0, 30, or 60 g β-Ala per day to basal diet were allocated in a replicated 3 × 3 Latin square design. Each experimental period was 20 d, of which the first 15 d were for adaptation and the subsequent 5 d were for sampling. The results showed that β-Ala linearly increased the ruminal concentration of microbial crude protein (MCP) ( = 0.005), but it did not affect the ruminal concentrations of ammonia N and total volatile fatty acids ( > 0.10). β-Ala also linearly increased the dry matter (DM) ( = 0.009), organic matter (OM) ( = 0.017) and crude protein (CP) ( = 0.043) digestibility, tended to decrease the acid detergent fiber digestibility ( = 0.077), but it did not affect the neutral detergent fiber digestibility ( = 0.641). β-Ala quadratically increased the relative abundance of ruminal Bacteroidota ( = 0.021) at the phylum level, and increased ( = 0.028) and ( = 0.014), and decreased the relative abundance of ( = 0.009) at the genus level. Feeding steers with β-Ala linearly increased the urinary N ( = 0.006), urea excretions ( = 0.002) and the N retention ( = 0.004), but it did not affect the N utilization efficiency ( = 0.120). β-Ala quadratically increased the plasma concentration of the total antioxidant capacity ( = 0.011) and linearly increased the plasma concentration of insulin-like growth factor-1 ( < 0.001). In summary, dietary supplementation with β-Ala improved the rumen MCP supply and increased the digestibility of DM, OM, CP and the N retention. Further research is necessary to verify the ruminal degradability of β-Ala and to investigate the mechanism of the impact of absorbed β-Ala on the anti-oxidative ability in steers.

中文翻译：

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通过对瘤胃细菌群落进行测序，阐明了膳食中添加 β-丙氨酸对肉牛瘤胃微生物粗蛋白供应、营养物质消化率和氮保留的影响


本研究调查了 β-丙氨酸 (β-Ala) 对肉牛瘤胃发酵、营养物质消化率、氮 (N) 代谢、血浆生化参数和瘤胃细菌群落的影响。六头初始体重为 252.8 ± 5.2 kg 的公牛，每天在基础日粮中添加 0、30 或 60 g β-Ala 进行 3 次处理，按重复的 3 × 3 拉丁方设计进行分配。每个实验周期为20 d，其中前15 d为适应期，随后5 d为采样期。结果表明，β-Ala线性增加瘤胃微生物粗蛋白（MCP）浓度（=0.005），但不影响瘤胃氨氮和总挥发性脂肪酸浓度（>0.10）。 β-丙氨酸还线性增加干物质（DM）（= 0.009）、有机物（OM）（= 0.017）和粗蛋白（CP）（= 0.043）的消化率，倾向于降低酸性洗涤纤维的消化率（= 0.077） ，但不影响中性洗涤纤维的消化率（=0.641）。 β-Ala 在门水平上使瘤胃拟杆菌门的相对丰度 (= 0.021) 呈二次方增加，在属水平上增加 (= 0.028) 和 (= 0.014)，并降低 (= 0.009) 的相对丰度。饲喂 β-Ala 后，尿氮 (= 0.006)、尿素排泄量 (= 0.002) 和氮保留量 (= 0.004) 呈线性增加，但不影响氮利用效率 (= 0.120)。 β-Ala 使总抗氧化能力的血浆浓度呈二次方增加（= 0.011），并使胰岛素样生长因子-1 的血浆浓度呈线性增加（< 0.001）。总之，日粮中添加 β-Ala 改善了瘤胃 MCP 供应，并增加了 DM、OM、CP 的消化率和 N 保留。 需要进一步研究验证β-Ala在瘤胃中的降解能力，并探讨吸收的β-Ala对公牛抗氧化能力的影响机制。