Rumen-protected lysine supplementation improved amino acid balance,nitrogen utilization and altered hindgut microbiota of dairy cows

This study was conducted to evaluate the effects of dietary crude protein(CP)and rumen-protected lysine(RPL)supplementation on lactation performance,amino acid(AA)balance,nitrogen(N)utilization and hindgut microbiota in dairy cows.Treatments were in a 2×2 factorial arrangement,and the main effects were CP concentration(16%vs.18%)and RPL supplementation(with or without RPL at40 g/cow per day).Forty cows were randomly allocated to 4 groups:low-CP diet(LP),low-CP diet plus RPL(LPL),high-CP diet(HP),high-CP diet plus RPL(HPL).The experiment was conducted for 8 weeks.Results showed that RPL increased the dry matter intake(P<0.01),milk protein yield(P=0.04)and energy corrected milk(P=0.04),and tended to increase milk fat yield(P=0.06)and fat corrected milk(P=0.05).Cows in the HP group tended to have higher milk urea N(P=0.07).Plasma concentrations of Arg,Ile,Lys,Met,Pro,total essential AA and total nonessential AA were increased by RPL(P<0.05).The total essential AA,total nonessential AA and most AA(except Ile,Phe,Gly and Pro)were increased in the HP group(P<0.05).N excretion was increased in the HP group through an increase in urea N excretion(P<0.01)and an upward trend in plasma urea N(P=0.07).In addition,RPL tended to increase milk protein N secretion(P=0.08),milk N(P=0.07)and microbial protein synthesis(P=0.06),and decreased plasma urea N(P<0.001).In the hindgut,the bacterial community were different between the LP and LPL groups(P<0.01).The probiotic abundances of Christensenellaceae_R-7_group and Acinetobacter were increased by RPL(P=0.03 and 0.03,respectively).The pathogenic abundances of Clostridium_sensu_stricto_1(P<0.001)and Turicibacter(P<0.01)were decreased by RPL.In conclusion,supplementing RPL with low dietary CP could balance AA supply and increase milk protein yield,resulting in an improvement in N utilization efficiency,and altered the composition of the hindgut microbiota to favor the lactation performance of dairy cows.

Analysis of cellulolytic and hemicellulolytic enzyme activity within the Tipula abdominalis （Diptera： Tipulidae） larval gut and characterization of Crocebacterium ilecola gen. nov., sp. nov., isolated from the Tipula abdominalis larval hindgut

In forested stream ecosystems of the north and eastern United States, larvae of the aquatic crane fly Tipula abdominalis are important shredders of leaf litter detritus. T. abdominalis larvae harbor a dense and diverse microbial community in their hindgut that may aide in the degradation oflignocellulose. In this study, the activities ofcellulolytic and hemicellulolytic enzymes were demonstrated from hindgut extracts and from bacterial isolates using model sugar substrates. One of the bacterial isolates was further characterized as a member of the family Microbacteriaceae. Taxonomic position of the isolate within this family was determined by a polyphasic approach, as is commonly employed for the separation of genera within the family Microbacteriaceae. The bacterial isolate is Gramtype positive, motile, non-sporulating, and rod-shaped. The G ＋ C content of the DNA is 64.9 mol%. The cell wall contains B2y type peptidoglycan, D- and L-diaminobutyric acid as the diamino acid, and rhamnose as the predominant sugar. The predominant fatty acids are 12-methyltetradecanoic acid （ai-C15：0） and 14-methylhexadecanoic acid （ai-C17：0）. The isolate forms a distinct lineage within the family Microbacteriaceae, as determined by 16S rRNA sequence analysis. We propose the name Crocebacterium ilecola gen. nov., sp. nov., to accommodate this bacterial isolate. The type species is T202T （ATCC BAA-1359; GenBank Accession DQ826511）.

Gut microbiota-derived metabolites contribute negatively to hindgut barrier function development at the early weaning goat model

Early weaning induces intestinal injury,leading to a series of long-term symptoms such as inflammation,malabsorption and diarrhea.In this study,we hypothesized that microbes and theirmetabolitesmodulate the host's inflammatory response to early weaning stress in a goatmodel.A total of 18 female Tibetan goat kids(n?9)wereweaned fromtheirmothers at 28 d(D28)and 60 d(D60)postpartum.D60 and D28 groupswere fed the same solid diet ad libitum fromweaning to 75 d of age.The colonic epithelium was subject to RNAsequencing,the caecal digesta metabolomics were assessed by liquid chromatographyetandem mass spectrometry(LC-MS/MS),and the caecal microbiota composition was analysed by 16S ribosomal RNA gene sequencing.We foundthatearlyweaningsubstantially increased the colonic pro-apoptotic gene expressionof B-cell lymphoma associated X(Bax),caspase-9,and caspase-3,and decreased the expression of zonula occludens-1(ZO-1)and claudin-1(P<0.01).In addition,a significant Bacteroides acidifaciens enrichmentwas observed in the hindgut of early-weaned goats(P<0.01),which negatively correlated with lysophosphatidylcholine products.Similarly,the chemokine signaling,IL-17 signaling,and peroxisome proliferatorsactivated receptor(PPAR)signaling pathways were upregulated in the colonic mucosa of the early-weaned goats.By applying caecal microbiota transplantation from goats to defaunated C57/6J mice,we confirmed that caecalmicrobiota of D28 goat kids increased the relative abundance of B.acidifaciens and significantly upregulated the genes of Bax,G proteinecoupled receptor(GPR)109A,GPR 43,fatty acid binding protein 6,nuclear receptor subfamily 1 group H member 3,angiotensin converting enzyme 2,and IL-6 expression(P<0.05),and decreased ZO-1,and claudin-1 protein expression in the mice jejunum and colon(P<0.001).These results proposed that the hindgut microbiota andmetabolites mediate the barrier functionweakening duringearlyweaning,and the relative abundance of B.acidifacienswas negatively correlatedwiththe hindgut barrier gene expression.This studydemonstrateshowweaningstress canaffectkeyhostemicrobe interaction regulators in the hindgut,in a lysophosphatidylcholine dependent and independent manner.Furthermore,based on our mice data,these results are transferable to other mammal species.

Roles of LmCDA1 and LmCDA2 in cuticle formation in the foregut and hindgut of Locusta migratoria

Chitin deacetylases(CDAs,including CDAI and CDA2)are considered key enzymes for body cuticle formation and tracheal morphogenesis in various insect species.However,their functions in the formation of the cuticular intima of the foregut and hindgut are unclear.Here,we investigated the roles of their respective genes LmCDAI and Lm-CD42 in this process,in the hemimetabolous insect Locusta migratoria.Transcripts of LmCDAI and LmCDA2 were highly expressed both before and after molting in the foregut.In the hindgut,their expression was high only before molting.In both the foregut and hindgut,LmCDA1 protein was localized in the basal half of the chitin matrix(procuti-cle),whereas LmCDA2 was detected in the upper half of the procuticle.K nockdown of LmCDAI by RNA interference(RNAi)in 5th-instar nymphs caused no visible defcts of the hindgut cuticle.By contrast,the chitinous lamellae of the cuticular intima in the foregut of knockdown animals were less compact than in control animals.RNAi against LmCDA2 led to thickening of both the foregut and hindgut cuticles,with a greater number of thinner laminae than in the respective control cuticles.Taken together,our results show that LmCDAI and LmCDA2 have distinct,but overlapping,functions in chitin organization in the foregut cuticle.However,in the hindgut,this process seems independent of LmCDA1 activity but requires LmCDA2 function.Thus,the CDAs reflect tissue-specific differences in cuticular organization and function,which need further detailed molecular and histological analyses for full comprehension.

取食臭椿不同部位对沟眶象和臭椿沟眶象成虫消化解毒酶的影响

沟眶象Eucryptorrhynchus scrobiculatus和臭椿沟眶象E.brandti是取食单一寄主臭椿Ailanthus altissima不同部位的钻蛀性害虫。二者成虫羽化后交配之前均需补充营养,且取食臭椿不同部位(叶柄、1年生枝、2~3年生枝、主干)对其雌成虫生殖系统发育的影响差异显著。就臭椿沟眶象雌成虫而言,只有取食主干才能够产卵;而对沟眶象雌成虫来说,则只有取食2~3年生枝的无法产卵。本研究使用臭椿的4种不同部位(叶柄、1年生枝、2~3年生枝、主干)饲喂这两种象甲成虫,利用ELISA试剂盒测定两种象甲的3种解毒酶(谷胱甘肽转移酶、羧酸酯酶和细胞色素P450)和3种消化酶(胰蛋白酶、淀粉酶、脂肪酶)的酶活性。结果表明,两种象甲中后肠的6种酶活性在取食不同寄主部位后发生显著性差异。其中,臭椿沟眶象雌成虫取食主干显著降低其中后肠的CarE酶活性,沟眶象雌成虫取食2~3年生枝能显著提高中后肠的CarE酶活性,同时降低中后肠AMY酶活性。本文明确了寄主植物不同部位对这两种象甲成虫中后肠消化解毒酶活性的影响,分析了两种象甲初羽化雌成虫补充营养造成生殖系统发育差异的原因,对后续这两种象甲消化解毒酶相关研究有一定参考价值。

红脂大小蠹后肠挥发性物质的鉴定、触角电位和室内趋向实验

对外来松树害虫红脂大小蠹DendroctonusvalensLeConte的信息化学物质进行了研究。通过GC_MS测定 ,鉴定出红脂大小蠹后肠挥发性物质中 ,除了含有松树挥发性物质α_蒎烯、β_蒎烯、3_蒈烯、月桂烯和柠檬烯外 ,还含有马鞭草烯醇和马鞭草烯酮 ;利用触角电位技术 ,对马鞭草烯醇、马鞭草烯酮以及在林间引诱效果最好的 3_( + )_蒈烯进行了触角电生理测试 ;利用Y_型双向选择嗅觉仪对这些物质进行了室内趋向实验。实验结果表明 :1 μg的马鞭草烯醇、马鞭草烯酮和 3_( + )_蒈烯引起雌雄触角的电位反应分别达 4 1 6 μV 470 μV、5 97μV 6 3 0 μV和 92 6 μV 1 0 99μV。浓度为 1 μL mL的马鞭草烯酮引起红脂大小蠹的正趋向反应 ,而在 1 0 0 μL mL浓度下引起红脂大小蠹的负趋向反应 ;在 1 μL mL的浓度下 ,3_( + )_蒈烯引起了红脂大小蠹正趋向反应 ,而马鞭草烯醇则对红脂大小蠹具有驱避作用 ,说明这些物质在红脂大小蠹搜寻寄主和调节虫口密度方面起着重要作用。

益生菌Lactobacillus amylovorus S1对仔猪后肠菌群的影响

结合PCR/DGGE(Denaturinggradientgelelectrophoresis,变性梯度凝胶电泳)和16SrDNA序列分析技术,研究添加益生菌LactobacillusamylovorusS1后仔猪从7至35日龄(断奶后两周)后肠菌群的变化。6窝新生仔猪被随机分成两组:对照组和处理组,处理组仔猪于7、9和11日龄口服L.amylovorusS1菌液(活菌数5×109CFU/mL)。分别于7、14、21、24和35日龄,每窝随机屠宰一头仔猪,收集肠道样品。比较不同日龄仔猪后肠菌群DGGE图谱表明,断奶后图谱中多数高GC含量细菌条带消失,至断奶后两周又逐渐出现。序列分析显示,这些高GC含量细菌主要为乳酸杆菌。统计分析表明,仔猪口服益生菌S1对其盲肠和结肠菌群的多样性指数无显著影响。通过比较处理组和对照组图谱发现,处理组14日龄出现一特异条带,与其匹配的序列的最相似已知菌为Clostridiumdisporicum,相似性为95%;而35日龄对照组有一特异优势条带,该条带被鉴定为猪链球菌(Streptococcussuis),相似性为99%。

粗蛋白水平对绵羊日粮养分后肠道消化的影响

本文旨在探讨粗蛋白(CP)水平对绵羊日粮养分后肠道及全消化道消化的影响。试验选4只装有永久性回肠瘘管的4月龄阉羊进行4×4拉丁方试验,定量饲喂4种等能量、相同中性洗涤纤维(NDF)水平、CP水平分别为11.8%(P12组)、14.0%(P14组)、15.9%(P16组)和17.8%(P18组)的日粮。结果表明:随着CP水平提高,日粮DM消化率显著(P<0.05)增加,有机物(OM)消化率无显著变化,CP消化率提高(P<0.01),NDF、酸性洗涤纤维(ADF)、半纤维素(HC)和纤维素(CEL)消化率增加(P<0.01),P12组的各项指标最低。日粮养分后肠道消化占总消化量的比率DM分别为31.3%、29.1%、28.8%和28.6%;OM分别为22.4%、20.8%、20.3%和20.0%;CP分别为19.3%、15.1%、14.3%和13.7%;NDF相应为28.2%、24.7%、23.4%和22.8%;ADF相应为25.3%、21.1%、19.9%和19.4%,P12组日粮ADF后肠道消化比率显著(P<0.05)高于其他3种日粮;HC分别为32.0%、29.5%、27.9%和27.4%;CEL分别为21.1%、18.9%、18.1%和17.9%,P12组日粮CEL后肠道消化比率显著(P<0.05)高于其他3种日粮;淀粉在后肠道消化不到1%。不同的粗蛋白水平对绵羊日粮养分后肠道的消化有一定的影响。

饲粮直/支链淀粉比对黄羽肉鸡血液生化指标和后肠微生物菌群的影响

本文旨在研究饲粮直/支链淀粉比对黄羽肉鸡血液生化指标和后肠微生物菌群的影响。试验采用单因子设计,选用29日龄黄羽肉鸡320羽,随机分为4个处理,每处理5个重复,每重复16羽,分别饲喂直/支链淀粉比为0.11、0.23、0.35、0.47的试验饲粮。试验期28d,测定了肉鸡的屠宰性能、血液生化指标和后肠道微生物菌群变化情况。结果表明:饲粮直/支链淀粉比显著影响试鸡的腹脂率(P<0.01)和食后0.5h血液中葡萄糖和胰岛素含量(P<0.05),但对血液乳酸和尿素氮含量无显著影响(P>0.05)。提高饲粮直/支链淀粉比显著增加后肠中肠球菌、乳酸杆菌和双歧杆菌数(P<0.05),显著减少大肠杆菌数(P<0.05)。以上提示饲粮直/支链淀粉比的差异会改变肉鸡体内葡萄糖释放速度和氨基酸代谢的关系,进而影响血液生化指标及后肠道微生物菌群,饲粮适宜直/支链淀粉比有利于肉鸡胴体品质改善和维持后肠微生物平衡。

不同pH对糙海参消化酶活性的影响

研究了不同pH条件下糙海参前肠、中肠及后肠的蛋白酶和淀粉酶比活力的变化.结果表明:1)糙海参前肠和中肠在pH=3,后肠在pH=10时,其蛋白酶的比活力最高;糙海参前肠和中肠蛋白酶的最适pH值在酸性范围,后肠蛋白酶的最适pH值在碱性范围;2)糙海参前肠淀粉酶在pH=3,中肠和后肠淀粉酶在pH=7时,其比活力最高,前肠淀粉酶的最适pH值在酸性范围,中后肠淀粉酶的最适pH值在中性或偏碱性范围;3)糙海参的整个肠道均能消化蛋白质与淀粉,中后肠是淀粉消化的主要场所;4)淀粉酶的比活力高于蛋白酶的比活力,这与其摄食底栖藻与腐屑的食性相吻合.

反刍动物后肠道对碳水化合物的消化吸收研究进展

本文就反刍动物后肠道的容积、食糜存留时间、微生物、淀粉及纤维物质的消化能力及影响因素、VFA的产生与吸收以及后肠道对碳水化合物消化能力与利用等方面进行了综述。后肠道的内容物相当于瘤胃的 15 %～2 6 % ,大肠食糜存留时间为 10～ 2 9h ,5 %～ 30 %的纤维素和 30 %～ 4 0 %半纤维素在大肠消化 ,产生的VFA相当于总产量的 8%～ 17% ,提供相当于进食量 8.6 %的代谢能 ,满足机体 5 %～ 13%的葡萄糖需要。

体外法探究果寡糖对猪后肠微生物代谢苯丙氨酸和色氨酸的影响

旨在采用体外发酵技术探究不同剂量果寡糖(FOS)对猪后肠发酵液中苯丙氨酸和色氨酸代谢的影响。以育肥猪回肠、盲肠和结肠的食糜为接种物,发酵液中苯丙氨酸(Phe)和色氨酸(Trp)终浓度为10mmol·L^(-1),分别添加果寡糖(FOS)0、0.5和0.75g,37℃培养24h后采集样品,分析氨基酸、氨态氮(NH3-N)、微生物蛋白(MCP)、吲哚和粪臭素浓度,利用Real-time PCR定量细菌总菌数量变化。结果表明,Phe和Trp均存在肠段差异性,FOS显著影响Phe在盲肠的降解率、NH3-N、MCP、粪臭素浓度和总菌数量(P<0.05),但对吲哚无显著影响(P>0.05);0.75g FOS显著降低后肠Trp降解率(P<0.05);Trp是影响发酵液中吲哚和粪臭素产生的主要因素。FOS可改变Phe和Trp的发酵类型,降低发酵液中Trp向粪臭素的转化。

生长育肥猪后肠纤维分解菌的数量及微生物发酵作用

本试验采用严格厌氧微生物学方法 ,对生长肥育猪的盲肠、结肠和直肠内容物中总厌氧菌和纤维分解菌的数量、纤维素酶活性、氨态氮和VFA含量进行了测定。结果表明 ,盲肠和直肠内容物中纤维分解菌的数量显著高于结肠(P<0.01) ;盲肠内容物中羧甲基纤维素酶活性最高 ,其次是结肠 ,直肠最低(P<0.05) ;直肠和盲肠的氨态氮浓度显著高于结肠(P<0.05) ;盲肠、结肠和直肠的总VFA含量分别为82.79、154.47和143.80mmol/L ;乙酸的摩尔百分比为盲肠>结肠>直肠 ;丙酸的摩尔百分比无明显改变 ;丁酸的摩尔百分比为盲肠<结肠<直肠(P>0.05)。本试验证明 ,饲喂玉米—豆粕型日粮的生长肥育猪后肠中存在相当数量的纤维分解菌 ,盲肠、结肠和直肠内容物中纤维分解菌的数量分别占可培养微生物区系的8.6 %、3.1 %和22.1 %。后肠微生物发酵类型为乙酸发酵型。

蝗虫肠道微生物总DNA提取方法的比较

采用Bead beating法和QIAamp DNA stool mini kit法提取蝗虫肠道微生物总DNA,并对2种方法提取DNA的得率、完整性以及16SrRNA基因扩增产物的变性梯度凝胶电泳(denaturing gradient gel electrophoresis,DGGE)图谱等进行综合比较。结果表明,Bead beating法提取DNA的得率显著高于QIAamp DNA stool mini kit法(P=0.042),而QIAamp DNA stool mini kit法提取DNA片段更完整。PCR-DGGE检测微生物多样性结果显示,QIAamp DNA stool mini kit法提取DNA所代表的微生物群落多样性略高于Bead beating法,但Mann-Whitley统计学检验表明用2种方法检测蝗虫肠道微生物多样性无显著差异(P=0.17)。因此在蝗虫肠道微生物群落多样性的检测中QIAamp DNA stool mini kit法具一定的优势,而Bead beating法同样适用。

青干草颗粒度对绵羊日粮养分后肠道消化的影响

为探讨粗饲料颗粒度对反刍动物饲粮养分在后肠道及全消化道消化的影响,本试验将饲粮中的粗料青干草进行整草、长铡草(4～6cm,长草)、短铡草(1～3cm,短草)和粉碎(0.5cm,粉草)4种颗粒度的机械加工后进行定量饲喂(4×4拉丁方试验)。结果表明:1)青干草不同颗粒度饲粮在后肠道消化量占总消化量的比率为干物质28.50%～32.64%、粗蛋白14.63%～19.76%、中性洗涤纤维24.31%～28.00%、酸性洗涤纤维21.76%～25.08%;粉草饲粮中的干物质、粗蛋白、中性洗涤纤维的后肠道消化量占总消化量的比率均显著(P<0.05)高于其他3种饲粮,酸性洗涤纤维的比率则极显著(P<0.01)高于其他饲粮;2)4种饲粮的干物质、粗蛋白和酸性洗涤纤维全消化道表观消化率未发生明显改变,粉草饲粮的中性洗涤纤维全消化道表观消化率则明显(P<0.05)降低。由此可见,粗饲料颗粒度过小,降低饲粮养分在瘤胃和小肠的消化,饲粮养分在后肠道的消化增加。

地顶孢霉培养物对奶牛乳中氨基酸和后肠道菌群的影响

为了研究地顶孢霉培养物对奶牛乳中氨基酸和后肠道菌群的影响,试验选择30头荷斯坦奶牛,根据产奶量、泌乳天数和胎次随机分为3组,分别饲喂基础日粮、基础日粮+15 g/d地顶孢霉培养物、基础日粮+30 g/d地顶孢霉培养物,预试期7 d,正试期56 d,在正试期的第28,56天收集奶样,测定乳中的氨基酸含量;在正试期的第54,55,56天收集粪样,测定后肠道中大肠杆菌、乳酸菌和双歧杆菌的数量。结果表明:地顶孢霉培养物显著提高了乳中总氨基酸(P<0.05)、必需氨基酸(P=0.02)和风味氨基酸(P<0.05)的含量。与对照组相比,添加地顶孢霉培养物组奶牛后肠道乳酸菌的数量显著提高(P<0.05)。说明地顶孢霉培养物对提高乳质量和改善乳风味有积极影响,并且能够提高奶牛后肠道益生菌数量,且30 g/d的添加量效果最好。

斜纹夜蛾幼虫肠道不同部位对Zn^(2+)积累作用的比较研究

在人工饲料中添加不同浓度的Zn2+连续胁迫3个世代的斜纹夜蛾Spodoptera litura Fabricius幼虫,采用等离子体原子发射光谱仪检测分析了连续3个世代6龄幼虫肠道不同部位对食物中Zn2+的积累作用。结果表明,Zn2+可在六龄幼虫前、中和后肠中积累,积累量受到食物中Zn2+的浓度和胁迫世代数的双重影响。每个世代6龄幼虫前肠、中肠和后肠中的Zn2+含量均随着饲料中Zn2+浓度增加而增加。六龄幼虫肠道3个不同部位对Zn2+的积累作用依次为前肠<中肠<后肠。而随着胁迫世代数的增加,不同世代6龄幼虫前肠、中肠和后肠中的Zn2+含量表现出显著减少的趋势。因此,植食性昆虫消化道不同部位对食物中Zn2+的积累作用有所不同,并随着胁迫世代数的增加而显著减少。

中华绒螯蟹肠道肥大细胞的组织化学研究

目的应用2种染色方法对中华绒螯蟹肠道肥大细胞进行组织化学定位。方法甲苯胺蓝(TB)和阿尔新兰-藏红染色(AB/SO)对中肠,后肠和之间的肠球进行了染色。结果 TB和AB/SO两种染色均能不同程度的显示中华绒螯蟹肠道肥大细胞,且TB更为适合。肠道粘膜上皮肥大细胞的形态主要为椭圆形或者圆形。中肠的前段和中段的肥大细胞主要分布在粘膜层的上皮细胞、基膜及外膜的结缔组织中;后肠的肥大细胞主要分布在粘膜下层的结缔组织颗粒和肠腺中;肠球中肥大细胞主要分布在肠球边缘少数存在的嗜酸性颗粒和嗜碱性颗粒中。结论中华绒螯蟹肠道肥大细胞具有与其他动物有相似之处,但是也存在自身的特异性。

华山松大小蠹化学信息物质

在常温下(25℃)解剖华山松大小蠹(Dendroctonus armandi Tsai et Li)的雌、雄虫,以正己烷为溶剂提取华山松大小蠹的后肠和粪便挥发物,并进行GC-MS分析。结果表明:在室温状态下,雌虫后肠挥发物中含有23种物质,主要为萜酸类、萜烯类、雌雄甾类、醇类和醛类等;雄虫后肠中有25种,以有机酸(树脂型萜酸居多)、酯类化合物和萜烯类化合物为其主要成分;粪便中有33种,树脂型的萜酸最多。华山松大小蠹的化学活性物质以萜类化合物为主。

壳聚糖对奶牛后肠道微生物的影响

研究日粮中添加不同水平壳聚糖对奶牛后肠道总需氧菌、大肠杆菌和乳酸菌数量的影响。试验按照产奶量、产犊日期、胎次等相近的原则，选取40头泌乳中期的荷斯坦奶牛随机分为5组。5种日粮分别是在基础日粮（风干基础）中添加0、500、1000、1500和2000mg／kg的壳聚糖配制而成。结果表明：日粮中添加1500～2000mg／kg＆聚糖能显著促进奶牛后肠道乳酸菌的增殖；而总需氧菌、大肠杆菌未出现明显变化。