| Rumen microbes play a vital role in maintaining health and improving feed efficiency of ruminant animals, and the compositon structure of these microbes would change with the age. But the present studies on rumen microbial developmental changes are scarcely reported. To address this, the present study used goats as the experimental animals to extract total DNA of rumen fluid that was sequenced by high-throughput sequencing technology, aiming at comprehensively exploring the structure of rumen microbial community change with the age.We respectively selected ldya,7days,15days,1 month,2months,3months, 4months, 5months,6months, 1year,1.5years and 2years twelve age group, a total of 60 healthy goats and every group of 5 each, all the animals raised in accordance with the normal management process, all the age groups were used to explore the composition structure of Bacteria and Archaea except 1day and 2years age groups that were used to only explore the composition structure of Archaea. One hour after the morning feeding, rumen fluid was extracted via the mouth using a stomach tube with a rumen vacuum sampler and each animal extracted more than 50 ml rumen contents except the 1day age group was slaghter to collect rumen contents. Then the rumen fluid were filter by using high pressure-sterilized cheese cloth. After that, the total DNA of the rumen fluid was extracted. Universal prokaryote primer set 515F/806R were used to target the V4-V5 hypervariable region of 16S rRNA gene via Barcode-PCR amplicon and archaeal specific primer set (349F/806R) were used to amplify the V3-V4 hypervariable region of 16S rRNA via Barcode-PCR amplicon, and the purified products were sent to Macrogen Biotechnology Company for high throughput-sequencing using MiSeq sequencing platform. The subsequent data analysis was almost performed in QIIME1.8.0 pipeline software and the data significant difference was tested using IBM SPSS Statistics 22.The results show that (1) Bacteroidetes(44.07%±0.09), Proteobacteria (16.97%±0.05) and Firmicutes (9.45%±0.02) were the predominant ruminal bacterial phyla among different age groups. The abundance of Bacteroidetes increased from 7days to 3months and then gradually decreased until 6months before it kept stable level, while that of Proteobacteria had the opposite trend. In the archaea, Euryarchaeota (84.02%±0.10) and Crenarchaeota (14.38%±0.10) were the predominant phyla among different age groups. The abundance of Euryarchaeota gradually increased from 1day to 15days, afterwards, the change of abundance was not significant difference although there was a fluctuation, whereas that of Crenarchaeota had the opposite trend at the same period, and then had the same trend. At the family levlel, Prevotellaceae (29.87%±0.16), Unclassified Bacteroidales (5.60%±0.04), Geobacteraceae (7.26%±0.07), Enterobacteriaceae (4.44%±0.47) were the most dominant rumen bacterial families among different age groups. The abundance of Prevotellaceae increased from 7days to 4months and then sharply decreased from 4months to 1.5years. In the archaea, Methanobacteriaceae (44.91%±0.19), Thermoplasmatales_incertae_se (17.99%±0.11) were the most dominant rumen archaeal families among different age groups which all belonged to Euryarchaeota. At the genus level, Prevotella (23.72%±0.17),Geobacter (5.60%±0.04), Escherichia/Shigella (4.11%±0.05) Paraprevotella (1.7%±0.01) were the predominant rumen bacterial genera among different age groups. The abundance of Prevotella increased from 7days to 3months and then gradually decreased. In the archaea, Methanobrevibacter (44.66%±0.19) Thermogymnomonas (17.99%±0.11) were the predominant rumen archaeal genera which all belonged to Euryarchaeota. (2) Analyzing the Alpha diversity within different age groups and we found that the Alpha diversity indices of 7days age group was more than other age groups. In the archaea,6months age group had the hightest value of observed_species (170.6),15days age group had the highest value of chaol (264.35) and 1.5years age group has the highest value of Shannon (4.93). (3) Beta analysis between different age groups, we found that 1.5years age group had the lowest distance value (0.60±0.31), while 3months age group had the highest that (0.76±0.40). In the archaea,2years age group had the lowest distance value of 0.19±0.04, while 5months age group had the highest that of 0.61±0.19 (4) Analyzing the bacterial core flora (≥0.1%) among different age groups, we found that 7days age group had the most core flora, with 79 shared genera, while the core flora shared by all the age groups only had 42 shared genera. In the archaea, there were only Methanobrevibacter and Thermogymnomonas that shared by all age groups.In a word, some rumen microbiome (Bacteroidetes, Proteobacteria, Euryarchaeota and Crenarchaeota) that are predominant in the mature rumen could be detected after birth and their abundances varied regularly from birth to adult. Meanwhile, the composition structure of bacteria within different age groups had a significant difference after birth for a period of time but it became stable when the animals become mature (1.5years), and the composition structure of archaea within different age groups had a significant difference before 5months followed by a gradual decrease, and then remained stable. |
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