饲粮精粗比对早期断奶藏羔羊小肠细菌多样性的影响

Effect of Dietary Concentrate to Forage Ratio on Intestinal Bacterial Diversity of Early Weaned Tibetan Lambs

【目的】本文旨在研究饲粮精粗比例对藏羔羊小肠细菌多样性的影响。【方法】选取210只早期断奶藏羔羊,随机分为7组,每组30只,分别给以精粗比例为80∶20、70∶30、60∶40、50∶50、40∶60、30∶70、20∶80的基础饲粮,预饲期10 d,试验期90 d。试验结束后,每组随机选择3只试验羊屠宰,采集小肠食靡样品,通过ITS高通量测序技术测定空肠细菌丰度及多样性指数。【结果】(1)Ace、Chao1指数变化趋势相似,精粗比40∶60组显著高于其余各处理组;各处理组间和组内Beta多样性没有明显差异(P>0.05)。(2)对门水平细菌分布前十菌群门类进行显著性分析,各处理组优势菌门均为变形菌门,其丰度均大于30.7%,且60∶40组远高于其余各组(P<0.05);酸杆菌门有随着精粗比降低而降低的趋势,但无显著性差异(P>0.05);30∶70组厚壁菌门丰度显著高于其余各处理组(P<0.05);80∶20、50∶50组软壁菌门丰度显著高于其余各组(P<0.05);芽单胞菌门和绿弯菌门分布趋势相似,均为60∶40组显著高于其余各组(P<0.05),且随着精粗比变化有先升高后降低的趋势。(3)科水平下:鞘脂单胞菌科为优势菌科,且60∶40组丰度高于其余各处理组(P<0.05);支原体科各处理组无显著差异(P>0.05),但80∶20、70∶30组分别有个体支原体菌科占据小肠细菌90%以上;80∶20组Pyrinomonadaceae最高(P<0.05),且有随精粗比降低而丰度下降的趋势;黄色杆菌科30∶70组显著高于其余各处理组(P<0.05);毛螺旋菌科40∶60组高于其余各组(P<0.05),芽单胞菌科和噬几丁质菌科的丰度随着精粗比的增高,且在60∶40组时达到最高值(P<0.05)。(4)小肠细菌功能基因集中于46个代谢途径,多集中于氨基酸代谢方面、碳水化合物代谢、生物膜转运等方面。【结论】探索了不同精粗比饲粮肠道微生物的组成和结构变化。在本试验条件下,随着饲粮精粗比变化,小肠微生物多样性和丰度均呈现不同程度变化,群落组成与结构也有相应的变化;当饲粮精粗比为60∶40时小肠微生物更适合定植生长。

【Objective】The present study aimed to study the effect of dietary concentrate to roughage ratio on bacterial diversity in small intestine of Tibetan lambs.【Method】210 early weaned Tibetan lambs were randomly divided into 7 groups,30 in each group,they were given basal diet with concentrate to roughage ratio of 80∶20,70∶30,60∶40,50∶50,40∶60,30∶70,20∶80,and the prefeeding period was 10 days and the experimental period was 90 days.At the end of the experiment,3 sheep in each group were slaughtered and the samples of intestinal food were collected,and the abundance and diversity index of jejunum bacteria were determined by its high-throughput sequencing technology.【Result】(i)The change trend of ACE and Chao1 index was similar,the concentration to roughage ratio of 40∶60 group was significantly higher than that of other treatment groups;There was no significant difference in beta diversity between and within the treatment groups(P>0.05).(ii)According to the significance analysis of the top ten bacterial groups at the phylum level,the dominant flora in each treatment group was Proteobacteria,the abundance of which was more than 30.7%,and the 60∶40 group was much higher than the other groups(P<0.05);The Acidobacteria decreased with the decrease of the concentrate to crude ratio,but there was no significant difference(P>0.05).The abundance of Firmicute in 30∶70 group was significantly higher than that in other treatment groups(P<0.05)The distribution trend of Tenericutes and Gemmatimonadetes in the 60∶40 group was significantly higher than that in the other groups(P<0.05),and with the change of the concentrate to crude ratio,the abundance of Chloroflexi in the 80∶20 and 50∶50 groups was significantly higher than that in the other groups(P<0.05).(iii)At the family level,Sphingomonadaceae was the dominant family,and the abundance of 60∶40 group was higher than that of other treatment groups(P<0.05);There was no significant difference in Mycoplasmataceae(P>0.05),but individual Mycoplasmataceae accounted for more than 90%of small intestinal bacteria in 80∶20 and 70∶30 groups respectively;The highest content of Pyromonadaceae was in 80∶20 group(P<0.05),the abundance of Xanthobacteraceae in 30∶70 group was significantly higher than that in other treatment groups(P<0.05);The abundance of Lachnospiraceae in 40∶60 group was higher than that in other groups(P<0.05).The abundance of Gemmatimonadaceae and Chitinophagaceae increased with the increase of concentrate to roughage ratio,and reached the highest value in 60∶40 group(P<0.05).(iv)The functional genes of small intestinal bacteria were concentrated in 46 metabolic pathways,mostly in amino acid metabolism,carbohydrate metabolism,biofilm transport and so on.【Conclusion】The composition and structure changes of intestinal microflora in diets with different concentrate to roughage ratios were explored.Under the experimental conditions,the diversity and abundance of small intestinal microorganisms changed in different degrees with the change of dietary concentrate to forage ratio,and the composition and structure of community also changed accordingly;When the ratio of concentrate to roughage was 60∶40,the small intestinal microorganisms were more suitable for colonization and growth.