本试验旨在研究猪肠道微生物对不同分子结构蛋白质饲料源（大豆蛋白质、大豆肽、单体氨基酸）氨基酸消失率的差异性。选取3头30 kg左右的健康生长猪，屠宰后分别无菌取50 mL空肠、回肠和盲肠内容物置于500 mL厌氧基础培养基中，梯度离心获得相应肠道微生物悬混液。在250 mL锥形瓶中加入50 mL厌氧基础培养基，先取5 mL空肠微生物悬混液接种于50 mL预热的培养基中培养4 h后取5mL培养液用于氨基酸含量和酶活性测定，再加入5 mL回肠微生物悬混液继续培养4 h后取5 mL培养液用于氨基酸含量和酶活性测定，最后加入5 mL盲肠微生物悬混液继续培养4 h后取5 mL培养液用于氨基酸含量和酶活性测定。试验分为3组，分别为大豆蛋白质组（基础培养基+大豆蛋白质+微生物）、大豆肽组（基础培养基+大豆肽+微生物）和单体氨基酸组（基础培养基+单体氨基酸+微生物），另设1个负对照组（基础培养基+微生物），3个正对照组（基础培养基+大豆蛋白质、基础培养基+大豆肽和基础培养基+单体氨基酸），每组设3个重复。结果表明：空肠、回肠、盲肠中微生物对3种不同分子结构蛋白质饲料源的赖氨酸脱羧酶、精氨酸脱羧酶、组氨酸脱羧酶、甘氨酸脱羧酶、酪氨酸脱羧酶、谷草转氨酶、谷丙转氨酶和腺苷脱氨酶活性均有显著或极显著影响（P<0.05或P<0.01），单体氨基酸组酶活性整体上高于其他2组，3组间酶活性大小与氨基酸的消失率高低并不完全一致。不同分子结构蛋白质饲料源在加入不同肠道的微生物培养后氨基酸消失率存在极显著差异（P<0.01）。大豆蛋白质组的氨基酸消失率由高到低依次为：盲肠、空肠、回肠，结构较为简单的大豆肽组和单体氨基酸组的氨基酸消失率由高到低依次为：回肠、盲肠、空肠，大豆蛋白质组的总氨基酸消失率最高。综上，在肠道微生物体外培养下，3种不同分子结构形式的蛋白质饲料源之间氨基酸的消失率存在较大差异，肠道微生物对大豆蛋白质的分解更活跃。

The aim of this study was to investigate the differences of pig intestinal microbes on amino acid disappearance rates of protein feed sources (soybean protein, soybean peptide and monomeric amino acid) with different molecular structure. Three about 30 kg healthy growing pigs were selected and slaughtered, 50 mL jejunum, ileum and cecal digesta were sterile collected into 500 mL anaerobic basal medium, respectively, and jejunum, ileum and cecal microbial suspensions were got by gradient centrifugation. Firstly, 50 mL anaerobic basal medium were added into 250 mL conical flask, and 5 mL jejunal microbial suspension were inoculate into 50 mL preheated anaerobic basal medium. After cultured for 4 h, 5 mL jejunal culture medium were taken for the determination of amino acids contents and enzymes activities and 5 mL ileal microbial suspension were inoculate into the above culture medium. Secondly, after cultured for another 4 h, 5 mL ileal culture medium were taken for the determination of amino acid contents and enzyme activities and 5 mL cecal microbial suspension were inoculate into the above culture medium. After cultured for another 4 h, 5 mL cecal culture medium were taken for the determination of amino acid contents and enzyme activities. The experiment consisted of 3 groups, soybean protein group (basal medium+soybean protein+microbes), soybean peptide group (basal medium+soybean peptide+microbes) and monomeric amino acid group (basal medium+monomeric amino acid+microbes), and 1 negative control group (basal medium+microbes) and 3 positive control groups (basal medium+soybean protein, basal medium+soybean peptide and basic medium+monomeric amino acids) were also consisted, and each group had 3 replicates. The results showed that the activities of lysine decarboxylase, arginine decarboxylase, histidine decarboxylase, glycine decarboxylase, tyrosine decarboxylase, glutamic-oxalacetic transaminase, glutamic-pyruvic transaminase and adenosine deaminase of protein feed sources with 3 different molecular structure were affected significantly by jejunum, ileum or cecal microbes (P<0.05 or P<0.01). The enzyme activities in monomeric amino acid group were higher overall than those in the other two groups. The enzyme activities in 3 groups were not completely consistent with the disappearance rate of amino acids. There were extremely significant differences in amino acid disappearance rates of protein feed sources with different molecular structure cultured in different intestinal microbes (P<0.01). The disappearance rate of amino acids in soybean protein group ranged from high to low:cecum, jejunum, ileum. The disappearance rate of amino acids in soybean peptide and monomeric amino acid groups with simple structure ranged from high to low:ileum, cecum, jejunum. The disappearance rate of total amino acids in soybean protein group was the highest. In conclusion, in vitro cultivation of intestinal microbes, the disappearance rate of amino acids among 3 protein feed sources with different molecular structure are different, and intestinal microbes are more active in protein decomposition of soybean.