摘 要:
旨在探究不同水平酶解玉米蛋白粉(enzymatic corn gluten meal, MCGM)對斷奶仔豬生長性能、腸道屏障、消化酶活性和腸道微生物組成的影響。試驗選取240頭體重為(5.71±0.79) kg的健康斷奶仔豬(21日齡,杜×長×大),基于體重接近原則,隨機分配至5個試驗組:5%普通玉米蛋白粉(corn gluten meal, CGM)組,5%魚粉(fish meal, FM)組以及5%、10%和15%酶解玉米蛋白粉組(MCGM1、MCGM2和MCGM3),進行為期14 d的飼養(yǎng)試驗。結(jié)果顯示:1)MCGM1和FM組斷奶仔豬的料重比(F/G)顯著小于CGM、MCGM2和MCGM3組(Plt;0.05),MCGM2組糞便評分顯著高于其他試驗組(Plt;0.05)。2)與CGM、MCGM2和MCGM3組相比,MCGM1和FM組的十二指腸和空腸的胰蛋白酶和糜蛋白酶的活性顯著提高(Plt;0.05)。3)MCGM1和MCGM3組的十二指腸絨毛高度/隱窩深度(絨隱比)極顯著高于CGM組和FM組(Plt;0.05)。同時,與MCGM2和MCGM3組相比,MCGM1組的腸道屏障基因(Occludin和ZO-1)表達水平顯著升高(Plt;0.05)。4)MCGM1組仔豬回腸特征菌為f__Peptostreptococcaceae、o__Peptostreptococcales-Tissierellales和g__Terrisporobacter,盲腸中為o__Veillonellales-Selenomonadales;FM組仔豬回腸特征菌為g__Lactobacillus和g__Prevotella。綜上所述,添加5%的MCGM可以顯著提高斷奶仔豬十二指腸和空腸的消化酶活性,并能增強腸道屏障功能,進而改善生長性能。
關(guān)鍵詞:
酶解玉米蛋白粉;斷奶仔豬;生長性能;腸道健康
中圖分類號:
S828.5 """"文獻標志碼:A """nbsp;文章編號: 0366-6964(2025)02-0953-16
收稿日期:2024-03-03
基金項目:國家重點研發(fā)計劃項目-替代玉米新型能量飼料資源開發(fā)與產(chǎn)品創(chuàng)制(2022YFD1300605);中國農(nóng)業(yè)科學院科技創(chuàng)新工程項目(ASTIP-IAS07)
作者簡介:白國松(1999-),男,山東德州人,碩士,主要從事動物營養(yǎng)與飼料研究,E-mail: bgsyx2@163.com
*通信作者:馬 騰,主要從事動物營養(yǎng)與飼料研究,E-mail: mateng@caas.cn
Effects of Enzymatic Corn Gluten Meal on Growth Performance and Intestinal Microorganisms of Weaned Piglets
BAI" Guosong, TENG" Chunran, WANG" Junhong, ZHONG" Ruqing, MA" Teng*, CHEN Liang, ZHANG Hongfu
(State Key Laboratory of Animal Nutrition and Feeding, Institute of Animal Science, Chinese Academy of Agricultural Sciences, Beijing 100193," China)
Abstract:
The study aimed to investigate the effects of different levels of enzymatic corn gluten meal (MCGM) on the growth performance, intestinal barrier, digestive enzyme activities, and intestinal microbial composition of weaned piglets. A total of 240 healthy weaned piglets (21 days-age, Duroc × Landrace × Yorkshire) with an average body weight of 5.71 ± 0.79 kg were selected. Based on the principle of body weight, the piglets were randomly assigned to five experimental groups: 5% conventional corn gluten meal (CGM) group, 5% fish meal (FM) group, and 5%, 10%, and 15% enzymatic corn gluten meal groups (MCGM1, MCGM2, and MCGM3), respectively. The feeding trial lasted for 14 days. The results showed that: 1) The feed-to-gain ratio (F/G) of weaned piglets in the MCGM1 and FM groups were significantly lower than that in the CGM, MCGM2 and MCGM3 groups (Plt;0.05). The fecal score in the MCGM2 group was significantly higher than that in the other experimental groups (Plt;0.05). 2) Compared to the CGM, MCGM2 and MCGM3 groups, the activities of trypsin and chymotrypsin in the duodenum and jejunum of the MCGM1 and FM groups were significantly increased (Plt;0.05). 3) The villus-to-crypt ratio in the duodenum of the MCGM1 and MCGM3 groups were significantly higher than that in the CGM and FM groups (Plt;0.05). Additionally, compared to the MCGM2 and MCGM3 groups, the mRNA expression levels of intestinal barrier genes (Occludin and ZO-1) in the MCGM1 group were significantly elevated (Plt;0.05). 4) The characteristic bacteria in the ileum of piglets in the MCGM1 group were f__Peptostreptococcaceae, o__Peptostreptococcales-Tissierellales, and g__Terrisporobacter, and in the cecum were o__Veillonellales-Selenomonadales; the characteristic bacteria in the ileum of piglets in the FM group were g__Lactobacillus and g__Prevotella. In conclusion, the addition of 5% MCGM can significantly enhance the digestive enzyme activities in the duodenum and jejunum of weaned piglets, strengthen the intestinal barrier function, and thereby improve growth performance.
Key words:
enzymatic corn gluten meal; weaned piglets; growth performance; intestinal health
*Corresponding author: MA Teng,E-mail: mateng@caas.cn
魚粉(fish meal, FM)是仔豬飼料中的優(yōu)質(zhì)蛋白來源,但因漁業(yè)的過度捕撈和氣候變化等因素其供應(yīng)面臨挑戰(zhàn),進而影響其價格和供應(yīng)的可持續(xù)性[1]。豆粕作為常用植物蛋白源,因其含有較高的抗營養(yǎng)因子和纖維,高用量可能損害仔豬腸道健康[2]。因此,為仔豬尋找高品質(zhì)的飼料蛋白質(zhì)來源替代需求迫切。中國的玉米種植面積廣,玉米蛋白粉(corn gluten meal, CGM)作為濕磨法生產(chǎn)淀粉過程中的副產(chǎn)品,產(chǎn)量大,且具有高蛋白質(zhì)、低纖維和低抗營養(yǎng)因子的特點[3],已經(jīng)在水產(chǎn)養(yǎng)殖中部分替代FM取得成功[4-6]。但CGM中以醇溶蛋白為主,較低的生物利用率限制了其在畜禽飼料中的應(yīng)用。通過對CGM進行酶解處理[7],得到的酶解玉米蛋白粉(enzymatic corn gluten meal, MCGM)具有更小的平均分子量、更佳的水溶性、易吸收性和良好的抗氧化特性[8-10],成為一種有潛力的高質(zhì)量蛋白飼料原料。
保育期仔豬面臨斷奶、與母豬分離、環(huán)境和飲食轉(zhuǎn)變等多重壓力[11],且消化系統(tǒng)發(fā)育不成熟,對植物性蛋白和淀粉的消化能力相對較弱,容易發(fā)生腹瀉。因此,腸道健康狀況對仔豬的生長和整體健康至關(guān)重要[12],良好的腸道發(fā)育和健康不僅有助于提高生長性能[13],也是增強仔豬抗疾病能力的關(guān)鍵[14]。鑒于MCGM通過酶解增加了生物活性功能組分和生物利用率,在提高仔豬生長性能、腸道健康上有較大潛力,本研究旨在通過對比分析添加不同比例MCGM的飼糧與CGM及FM飼糧對保育豬的生長性能、腸道屏障、消化酶活性和腸道微生物組成的影響,以評估MCGM作為優(yōu)質(zhì)蛋白來源的實際應(yīng)用潛力。
1 材料與方法
1.1 原料
本研究所用的CGM和MCGM均由寧夏伊品生物科技有限公司(中國寧夏)提供,所用FM的原產(chǎn)地為秘魯(Pesquera Diamante S.A.)。CGM和MCGM的氨基酸組成見表1。
1.2 試驗設(shè)計與飼養(yǎng)管理
本試驗采用單因素完全隨機設(shè)計,共設(shè)置5個處理組,分別為:5%CGM飼糧、5%FM飼糧以及3個不同添加比例(5%、10%和15%)的MCGM飼糧(MCGM1、MCGM2和MCGM3)。每組的飼糧參照NRC(2012)仔豬營養(yǎng)需要量進行配制,其組成和營養(yǎng)水平見表2。
本試驗選擇體重、胎次接近的妊娠母豬20頭,隨機分為5組,每組4個重復,分娩后根據(jù)仔豬體重平均調(diào)配至每欄12頭(杜×長×大),共計240頭(20窩)。試驗組仔豬于7日齡開始分別飼喂不同處理的教槽料,以熟悉飼糧(7~20日齡)。于21日齡斷奶后,按照體重(5.71±0.79 kg)相近原則以備用仔豬替換個別體重過輕個體,所有仔豬均自由采食和飲水。
1.3 生長性能及糞便評分
在試驗開始和結(jié)束時稱量每只仔豬的體重,以計算平均日增重(ADG)。試驗期間,以每個欄為單位記錄飼料消耗量,以計算平均日采食量(ADFI)和料重比(F/G)。試驗期間,每天以欄為單位進行糞便評分,具體評分標準如下:1=正常、顆粒狀或條狀糞便;2=較軟、比正常糞便松散;3=黏稠、中度腹瀉的糞便;4=液體、嚴重腹瀉的糞便[15]。
1.4 樣本采集與檢測
在試驗結(jié)束時,從每個欄中挑選2頭體重接近組內(nèi)平均值的仔豬進行屠宰,進而收集解剖樣本。測量十二指腸、空腸、回腸和結(jié)腸的長度,并稱量心、肝、脾、肺和腎的重量,計算相應(yīng)的器官指數(shù)[器官重(g)/體重(kg)]。十二指腸、空腸和回腸的組織樣本在采集后立即使用0.9%生理鹽水清洗干凈,隨后用4%多聚甲醛固定,以便于后續(xù)的組織學檢查。同時,采集十二指腸、空腸和回腸的腸道黏膜以及十二指腸、空腸、回腸和盲腸的腸道內(nèi)容物樣本,存放于-80 ℃條件下,用于后續(xù)的屏障基因表達分析、消化酶活性分析和微生物組成檢測。消化酶(淀粉酶、脂肪酶、糜蛋白酶和胰蛋白酶)活性的測定采用標準化的市售檢測試劑盒(南京建成生物工程研究所,中國南京)進行。腸道屏障功能相關(guān)蛋白(ZO-1、Claudin1和Occludin)的表達水平通過定量PCR方法測定,參照Luo等[16]。所有引物均由美國國家生物技術(shù)信息中心(NCBI)設(shè)計。引物序列見表3。
1.5 腸道形態(tài)分析
采集的十二指腸、空腸和回腸的樣本經(jīng)過標準的脫水和石蠟包埋處理,切片后進行蘇木精-伊紅(HE)染色,之后在Leica DM2000光學顯微鏡(Leica Microsystems,Wetzlar,Germany)下對腸道組織結(jié)構(gòu)進行觀察并拍照記錄,使用Image J軟件(1.8.0版)對絨毛高度和隱窩深度進行測量,并據(jù)此計算絨毛與隱窩的比值。
1.6 微生物分析
使用Qiagen DNA分離試劑盒(Qiagen,Hilden,Germany)從腸道食糜樣本中提取DNA,使用引物338F(5′-AACTCCTACGGGAGGCAGCAG-3′)和806R(5′-GACTACHVGGGTWTCTAAT-3′)對細菌16S rRNA基因的V3-V4區(qū)域進行PCR擴增。擴增產(chǎn)物在Illumina HiSeq平臺上進行高通量測序,通過Majorbio I-Sanger云平臺(www.I-Sanger.com)進行數(shù)據(jù)分析。
1.7 統(tǒng)計分析
對生長性能、糞便評分、器官指數(shù)、腸道長度、消化酶活性等數(shù)據(jù)使用SAS 9.4(SAS Institute, Inc., Cary, NC, United States)進行方差分析(ANOVA)和多重比較(Duncan’s)。統(tǒng)計生長性能和糞便評分時,以豬欄為單位進行分析。Plt;0.05表示為具有顯著統(tǒng)計學意義。
2 結(jié) 果
2.1 MCGM對斷奶仔豬生長性能的影響
由表4可知,不同處理仔豬的初重、末重、ADG和ADFI均無顯著差異(Pgt;0.05)。MCGM1組和FM組的F/G顯著小于CGM組、MCGM2和MCGM3組(Plt;0.05)。MCGM2組仔豬的糞便評分顯著高于其他四組(Plt;0.05)。
2.2 MCGM對斷奶仔豬器官發(fā)育的影響
器官指數(shù)結(jié)果(表5)表明,不同組間的心臟、肝臟、脾臟、肺臟和腎臟器官指數(shù)均無顯著差異(Pgt;0.05)。表6顯示,不同處理的空腸、回腸和結(jié)腸的長度無顯著差異(Pgt;0.05),F(xiàn)M和MCGM1組的十二指腸長度顯著低于MCGM2和MCGM3組(Plt;0.05),與CGM組相比差異不顯著(Pgt;0.05)。
腸道組織形態(tài)統(tǒng)計結(jié)果表明(圖1),MCGM1和3組的十二指腸絨隱比極顯著高于CGM組和FM組,MCGM1組也極顯著高于CGM組(Plt;0.01,圖1C);與CGM組相比,F(xiàn)M、MCGM1和MCGM3十二指腸隱窩深度極顯著降低(Plt;0.01,圖1B)。仔豬空腸絨毛高度、隱窩深度和絨隱比沒有顯著差異(Pgt;0.05,圖1D~F)。在回腸中,F(xiàn)M和MCGM1組絨毛高度顯著低于CGM組(Plt;0.05,圖1G);MCGM1和MCGM3組的隱窩深度顯著低于CGM組(Plt;0.05;圖1H)。此外,仔豬回腸絨隱比沒有顯著差異(Pgt;0.05;圖1I)。
2.3 MCGM對腸道屏障基因表達的影響
如圖2所示,在十二指腸中,MCGM1組與緊密連接相關(guān)的基因——Occludin和ZO-1均高水平表達,顯著高于MCGM2和MCGM3組(Plt;0.05),MCGM1組ZO-1的表達量也顯著高于CGM組(Plt;0.05),但均與FM組差異不顯著(Pgt;0.05)。在空腸和回腸中,未發(fā)現(xiàn)上述基因顯著的差異表達(Pgt;0.05)。
2.4 MCGM對消化酶活性的影響
如表7所示,在十二指腸中,各試驗組淀粉酶活性差異不顯著(Pgt;0.05)。脂肪酶活性,F(xiàn)M、CGM和MCGM1組中顯著高于MCGM2和MCGM3組(Plt;0.05)。胰蛋白酶和糜蛋白酶活性FM和MCGM1組則顯著高于CGM、MCGM2和MCGM3組(Plt;0.05)。
在空腸中,F(xiàn)M和MCGM1組淀粉酶、胰蛋白酶和糜蛋白酶的活性均極顯著高于CGM、MCGM2和MCGM3組(Plt;0.01);MCGM1組脂肪酶活性顯著高于CGM、MCGM2和MCGM3組(Plt;0.05),與FM組差異不顯著(Pgt;0.05)。FM組脂肪酶活性則顯著高于MCGM2和MCGM3組(Plt;0.05)。
2.5 MCGM對回腸和盲腸糞便微生物的影響
回腸食糜和盲腸食糜的16S rDNA測序分析稀疏性曲線表明,各組的取樣均提供了足夠的序列
來反映回腸食糜和盲腸食糜中的微生物多樣性和細菌群落(圖3)。α多樣性分析結(jié)果顯示,不同處理仔豬回腸食糜的Chao指數(shù)無顯著差異(圖4B),然而,與CGM組相比,F(xiàn)M組糞便樣本中的Simpson指數(shù)顯著降低(Plt;0.05;圖4A)。不同處理仔豬盲腸食糜的Simpson指數(shù)、Chao指數(shù)和Shannon指數(shù)無顯著差異(Pgt;0.05)(圖4F~4H)?;啬cOTU-Venn分析在FM、CGM、MCGM1、MCGM2和MCGM3組中分別鑒定了23、29、20、16和5個獨特的OTUs(圖4D)。而盲腸OTU-Venn分析在FM、CGM、MCGM1、MCGM2和MCGM3組中分別鑒定了9、15、10、21和12個獨特的OTUs(圖4I)。PCoA分析表明,不同處理仔豬的回腸和盲腸微生物OTU組成存在顯著差異(Plt;0.05)(圖4E、4J)。
門和屬的微生物群落組成分析結(jié)果顯示,回腸食糜樣本在門水平上主要由Firmicutes, Actinobacteria, Proteobacteria和Cyanobacteria組成(圖5A)。CGM組具有最高水平的Cyanobacteria和Campilobacterota(圖5C)。FM組含有高水平的Bacteroidota(圖5C)。盲腸食糜樣本在門水平上主要由Firmicutes, Bacteroidota, Proteobacteria, Actinobacteria和Campilobacterota,組成(圖5E)。CGM組具有最高水平的Campilobacterota和較高水平的Spirochaetota(Plt;0.05)(圖5G)。MCGM3組具有最高水平的Spirochaetota, Desulfobacterota, Verrucomicrobiota和Patescibacteria(Plt;0.05)(圖5G)。
對回腸食糜(圖5B、5D)和盲腸食糜(圖5F、5H)中的腸道微生物群組成進行了進一步的屬一級分析?;啬c食糜中,F(xiàn)M組含有高水平的Lactobacillus(Plt;0.05),MCGM1組含有高水平的Terrisporobacter(Plt;0.05)。盲腸食糜中,F(xiàn)M組含有高水平的Prevotella(Plt;0.05),CGM含有高水平的Campylobacter(Plt;0.05),MCGM1組含有高水平的Streptococcus(Plt;0.05),MCGM2組含有高水平的norank_f__Butyricicoccaceae(Plt;0.05),MCGM3組則含有高水平的Escherichia-Shigella(Plt;0.05)。
為進一步探討不同處理微生物群組成的差異,本研究做了LEfSe分析,并以LDA得分≥2.0為標準進行表示。回腸食糜微生物結(jié)果(圖6A)顯示,F(xiàn)M組特征菌為g__Lactobacillus,CGM組特征菌為f__Pasteurellaceae,MCGM1特征菌為f__Peptostreptococcaceae,o__Peptostreptococcales-Tissierellales和g__Terrisporobacter,MCGM2特征菌為g__Enterococcus。
盲腸食糜微生物LEfSe分析結(jié)果(圖6B)顯示,F(xiàn)M組特征菌為g__Prevotella,CGM組特征菌為f__Campylobacteraceae和g__Campylobacter,MCGM1組特征菌為g__Streptococcus和o__Veillonellales-Selenomonadales,MCGM2組特征菌為f__Erysipelotrichaceae和g__norank_f__Butyricicoccaceae,MCGM3組特征菌為f__Enterobacteriaceae和g__Escherichia-Shigell。
3 討 論
3.1 MCGM在仔豬飼糧中的應(yīng)用
CGM是玉米淀粉生產(chǎn)過程中的副產(chǎn)品,中國每年可生產(chǎn)超過84萬噸的CGM[17-18]。CGM因其高蛋白、低纖維和低抗營養(yǎng)因子的特性[3],已經(jīng)在多種水產(chǎn)動物或畜禽中進行了應(yīng)用[4,19],但在豬上多集中于消化率的研究[20-21],而較少用于仔豬的飼養(yǎng),可能與CGM蛋白質(zhì)量較差相關(guān)[22]。目前已經(jīng)有研究表明,對CGM進行改性可以提高其應(yīng)用價值[23]。微生物發(fā)酵處理是CGM改性的一種常見手段,發(fā)酵過程可以很好地降解CGM中的大分子蛋白、改善營養(yǎng)特性和提高水溶性[24]。但微生物發(fā)酵過度依賴優(yōu)良菌株和發(fā)酵條件,且微生物在發(fā)酵過程中會消耗發(fā)酵底物中的營養(yǎng)物質(zhì),造成損失和產(chǎn)率下降[25]。而酶法改性則具有產(chǎn)率高的特點,同時酶解過程條件溫和,易于調(diào)控,可以根據(jù)需要選擇適宜的酶類型和使用量,且酶解過程沒有或很少產(chǎn)生不良副產(chǎn)物[8,10]。然而,對CGM進行酶解改性獲得的MCGM能否作為豬的優(yōu)質(zhì)蛋白來源,這有待進一步研究。同時,保育階段作為豬生長中的關(guān)鍵階段[26-27],經(jīng)常需要高質(zhì)量的蛋白原料。伴隨著魚粉等保育豬常用優(yōu)質(zhì)蛋白飼料資源的價格上漲[28],新的蛋白飼料資源急需進一步開發(fā)。
3.2 生長性能及消化酶活性
FM通常被用作豬飼糧中的優(yōu)質(zhì)蛋白原料,它含有豐富的限制性氨基酸,尤其是賴氨酸、蘇氨酸和色氨酸,其消化率也高于其他常規(guī)谷物。本試驗發(fā)現(xiàn),飼喂FM和MCGM1的仔豬比飼喂CGM、MCGM2和MCGM3的仔豬具有更高的ADG和更低的F/G,這表明與其他飼糧相比,F(xiàn)M和MCGM1組的仔豬具有更快的生長速度和更高的飼料轉(zhuǎn)化率。另外,在消化酶活性的測定中,F(xiàn)M和MCGM1組的斷奶仔豬十二指腸和空腸的胰蛋白酶和糜蛋白酶活性均高于其他組別。同時,F(xiàn)M和MCGM1組的十二指腸和空腸的脂肪酶活性以及空腸的淀粉酶活性也均高于其它組別。酶的活性的變化也可能是導致生產(chǎn)性能產(chǎn)生差異的一個原因[29],本研究中,F(xiàn)M和MCGM1可能通過提高消化酶的活性來改善動物的生產(chǎn)性能。而MCGM2和MCGM3飼糧的ADG卻較低,這可能與MCGM原料的黏性較高有關(guān)。MCGM在酶解后,小分子蛋白和肽比例增加,水溶性提高導致MCGM原料的黏度增加[30]。添加過高比例的MCGM可能會導致飼糧的適口性下降,進而對仔豬的生長性能產(chǎn)生負面影響。本研究中在生長性能方面,MCGM1日糧優(yōu)于CGM日糧,其效果與FM日糧相當。
3.3 腸道形態(tài)及腸道屏障功能
腸道形態(tài)和功能的改善直接關(guān)系到仔豬的整體健康和生長性能。本研究中,添加FM和5%MCGM組的仔豬的隱窩深度相對CGM組有所降低,絨隱比有所升高,而不同MCGM組間沒有顯著差異。腸道形態(tài)的結(jié)果表明,添加FM和5%MCGM一定程度上可以改善斷奶仔豬的腸道健康和消化吸收能力,因此這可能也是相應(yīng)處理ADG較高的原因。緊密連接是腸黏膜細胞之間最重要的連接方式,主要由跨膜蛋白(如Occludin)和胞膜蛋白(如ZO-1)組成,在維持腸黏膜通透性和上皮屏障完整性方面起著至關(guān)重要的作用[31]。斷奶應(yīng)激通常會通過破壞緊密連接蛋白增加腸道通透性[32],仔豬ZO-1的表達降低[33],導致病原菌和毒素的滲透增加,并增加腹瀉的發(fā)生率[34]。在本研究中,相比CGM組別,日糧添加5% MCGM可以顯著提高十二指腸中緊密連接蛋白基因的表達。
3.4 回腸微生物組成
微生物群落的多樣性和穩(wěn)定性對于腸道健康具有重要意義。α-多樣性可作為腸道微生物生態(tài)系統(tǒng)功能恢復力的指標,包括物種豐富度和物種多樣性[35]。本研究中,不同處理仔豬的盲腸微生物α多樣性沒有顯著差異。然而,與CGM相比,F(xiàn)M降低了仔豬回腸食糜樣本中的Simpson指數(shù),這表明FM在改善斷奶仔豬回腸微生物多樣性和維持腸道健康方面有良好的效果。通過PCoA分析得出的β多樣性表明,不同試驗組的回腸微生物群存在顯著變化,表明不同處理對仔豬回腸和盲腸食糜中微生物類群具有不同的影響。在門級水平上,回腸食糜樣本中的主要物種是Firmicutes,這與以往的研究結(jié)果一致[36-37]。CGM組為潛在致病菌的Campilobacterota水平顯著升高,這可能是該組別生長性能降低的一個原因。與其他組別相比,F(xiàn)M組含有高水平的Bacteroidota,被認為是降解植物多糖和其他難降解有機碳源和氮源的重要細菌[38],其高豐度有利于塑造腸道生態(tài)系統(tǒng)的代謝環(huán)境并預防腹瀉[39]。雖然不同處理組的糞便評分差異較小,但飼喂FM的仔豬Bacteroidota豐度較高,這可能有助于改善仔豬的腸道健康,進一步促進仔豬的生長性能。同時,在屬水平上,F(xiàn)M回腸食糜中含有高水平的Lactobacillus,而該菌屬是常見的益生菌,可以促進動物的免疫和腸道健康[40],這可能也是該組別具有較好生長性能的一個原因。關(guān)于10%MCGM組糞便評分較高,可能是由于在LEfSe分析結(jié)果表明MCGM2含有高水平的g__Enterococcus,該菌屬的常見于正常腸道微生物群[41-42],但有報道發(fā)現(xiàn)這是一種條件致病菌與仔豬腹瀉有關(guān)[43-44]。f__Peptostreptococcaceae是一種形態(tài)上多樣化的革蘭陽性微生物群[45],被認為是有益菌[46],這可能與MCGM1組具有更好的生長性能和腸道健水平有關(guān)。
3.5 盲腸微生物組成
相比回腸的微生物,盲腸食糜中微生物類群更加豐富,其中水平最高的Firmicutes比例有所下降,但含量也均在65%以上。CGM組具有高水平的潛在致病菌Campilobacterota和Spirochaetota[47],該結(jié)果與回腸食糜結(jié)果一致,這也表明CGM可能通過影響腸道微生物組成從而影響了仔豬腸道健康和生長性能。在屬水平上,F(xiàn)M組含有高水平的Prevotella,該菌屬具有潛在的益生作用[48];而15%MCGM組中發(fā)現(xiàn)了有高水平的Escherichia-Shigella,該菌與腸道炎癥高度相關(guān)[49]。LEfSe分析盲腸特異菌屬也得到了一致的結(jié)果,其中o__Veillonellales-Selenomonadales中很多菌群與腸道的穩(wěn)定和健康密切相關(guān)[50],在5%MCGM組仔豬腸道中作為具有顯著差異的益生菌,可能在改善仔豬腸道健康和生長性能上發(fā)揮了重要作用。
4 結(jié) 論
本研究中,5%添加水平的MCGM和FM均可提高斷奶仔豬的消化酶活性,并能改善腸道屏障功能和腸道微生物組成,進而提高生長性能。以上結(jié)果表明,MCGM具有作為斷奶仔豬優(yōu)質(zhì)蛋白原料的潛力,本試驗條件下,建議添加量為5%。
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