低蛋白质日粮对断奶仔猪生长相关激素和肠道微生物区系的影响

【目的】在饲喂低蛋白质日粮条件下,探究断奶仔猪生长相关激素、回肠和盲肠微生物组成及其代谢产物的变化。【方法】选取体重相近杜长大断奶仔猪54头,随机平均分为3组,每组18头,分别饲喂含20%(NP组)、17%(MP组)和14%(LP组)粗蛋白日粮,平衡日粮中的赖氨酸、蛋氨酸、苏氨酸和色氨酸,于试验第10、25和45天每组屠宰6头,采血测定血常规和生长相关激素;于第45天采集回肠和盲肠食糜,分析微生物及其代谢产物。【结果】与NP组相比,第25和45天时MP和LP组尿素氮水平显著降低(P0.05),第25天时LP组甘油三脂含量、第45天时LP组胆固醇含量显著增加(P0.05)。各时间点血液胰高血糖素、胰岛素、生长激素、T3和T4在3组之间差异均不显著。门水平上,回肠和盲肠中的微生物均以厚壁菌门占主导地位,但各组间差异不显著;随日粮蛋白质含量降低,乳酸杆菌属呈上升趋势,严格梭菌属呈下降趋势,但差异不显著。降低日粮蛋白质含量显著减少了回肠和盲肠中氨氮的产量(P0.05)。【结论】断奶仔猪日粮蛋白质降低3或6个百分点不影响机体生长相关激素的分泌,但能降低血液尿素氮和肠道内氨氮的浓度,对肠道有益菌乳酸杆菌属的相对丰度有一定的提高作用。这说明低蛋白质日粮能提高断奶仔猪对饲料氮源的利用率,且有利于肠道健康。

Effect of low-protein diet on hormones associated with growth and on gut microbiota in weaned piglets

Objective] To explore the effect of reducing dietary protein level on plasma hormones associated with growth and microbiota in digesta of ileum and cecum in weaned piglets. Methods] Fifty-four selected weaned piglets with similar body weight were assigned to three groups with three diets, each diet contained 20% CP, 17% CP or 14% CP supplemented with Lys, Met, Thr and Trp, according to NRC (2012) recommendation. At day 10, 25 and 45, blood samples were collected from jugular vein of six piglets in each group for analysis of blood parameters and hormones associated with growth. At day 45, we collected the digesta from ileum and cecum for microbiota and its metabolites analysis. Results] At day 25 and 45, diets with 17% CP and 14% CP decreased the concentration of blood urea nitrogen compared to control group (P<0.05). Low protein diets with 14% CP increased the cholesterol concentration at day 45 and increased the concentration of triglyceride at day 25 (P<0.05). But dietary protein level had no effect on glucagon, growth hormone, insulin, T₃ and T₄ in different time point (P>0.05). In phylum level, Firmicutes were dominant bacteria in ileum and cecum, however dietary protein level had no significant effect on the relative abundance of Firmicutes (P>0.05). Reducing dietary protein level tended to increase the relative abundance of Lactobacillus and decreased the relative abundance of Clostridium_sensu_stricto_1, but data was not significant (P>0.05). Reducing dietary protein by 3% or 6% significantly decreased the concentration of ammonia in ileum and cecum (P<0.05). Conclusion] Low-protein diet with 17% CP or 14% CP had no effect on the concentration of hormones associated with growth, whereas, it decreased the blood urea nitrogen and ammonia in digesta and tended to increase the relative abundance of Lactobacillus. The findings suggest that reducing dietary protein level increase the utilization of nitrogen and contribute to intestinal health.