3.2 Intestinal microbial diversity at different dietary protein
levels
Cluster Operational Taxonomic Units (OTUs) with 97% identity were
constructed based on Effective Tags for all samples. It is clear that
the OTU petals of the jejunum and cecum span the three protein levels
groups (Figure 1). Results reveal 438 OTUs in the jejunum and cecum at
different dietary protein levels. In addition, the total number of
unique OTUs in the jejunum at three different dietary protein levels was
167, significantly higher than the number in the cecum (116). A Venn
diagram of jejunum OTUs at three different protein levels is shown in
Figure 1. This presentation shows 560 OTUs present in Bamei pig jejunums
at the three different protein levels. The number of OTUs shared by the
control group, test group I and test group II were 224 and 53,
respectively, while the number of OTUs shared by test group I and test
group II was 93. A Venn diagram of cecal OTUs at three different dietary
protein levels can also be seen in Figure 1; this presentation shows
that the total number of OTUs is 702, while the total number of OTUs
shared between the control group, test group I and test group II are 109
and 49, respectively. The total number of OTUs in test group I and test
group II was 152; thus, unique OTUs present in the control group, test
group I, and test group II were 206, 113, and 60, respectively. As shown
by the dilution curve also presented in Figure 2, the amount of
sequencing data in this study is reasonable as it reflects information
about most microorganisms in samples. Results of an Alpha diversity
analysis at three different dietary protein levels is presented in Table
5; these data show that microbial diversity and abundances in jejunum
and cecum samples from Bamei pigs were different between the three
groups. The diversity and abundance of microbes in cecum samples from
Bamei pigs were significantly higher than those from jejunum samples
(P < 0.05). Data show that dietary protein levels
exerted no significant effect on Shannon index values for cecum microbes
in Bamei pigs, while Simpson, ACE, and Chao1 index values for test I
were significantly higher than those recovered for the control group and
test group II (P < 0.05). Dietary protein levels
exerted no significant effect on microbial diversity or abundance in
cecum samples from Bamei pigs (P > 0.05).
Comprehensive test results show that dietary protein levels can improve
intestinal microbe numbers in Bamei pigs and also tend to enhance both
microbial diversity and abundance (P < 0.1).