Bovine Colostrum Supplementation Modulates the Intestinal Microbial Community in Rabbits

Abstract

BC is a nutraceutical that can modulate intestinal microbiota. This study investigates the effects of BC diet supplementation on luminal and mucosa-associated microbiota in the jejunum, caecum, and colon of rabbits. Twenty-one New Zealand White female rabbits were divided into three experimental groups (n = 7) receiving a commercial feed (CTRL group) and the same diet supplemented with 2.5% and 5% BC (2.5% BC and 5% BC groups, respectively), from 35 (weaning) to 90 days of age (slaughtering). At slaughter, the digestive tract was removed from each animal, then both content and mucosa-associated microbiota of jejunum, caecum, and colon were collected and analysed by Next Generation 16SrRNA Gene Sequencing. Significant differences were found in the microbial composition of the three groups (i.e., beta-diversity: p < 0.01), especially in the caecum and colon of the 2.5% BC group. The relative abundance analysis showed that the families most affected by the BC administration were Clostridia UCG-014, Barnesiellaceae, and Eggerthellaceae. A trend was also found for Lachnospiraceae, Akkermansiaceae, and Bacteroidaceae. A functional prediction has revealed several altered pathways in BC groups, with particular reference to amino acids and lactose metabolism. Firmicutes:Bacteroidetes ratio decreased in caecum luminal samples of the 2.5% BC group. These findings suggest that BC supplementation could positively affect the intestinal microbiota. However, further research is needed to establish the optimal administration dose.

Keywords: Bacteroidetes; Firmicutes; caecum; microbiota; nutraceutical.

Figure 1

Pie charts representing the average composition of the microbiota for the samples divided by intestinal tract (jejunum, caecum, colon), sampling site (lumen, mucosa), and diet (CTRL, 2.5% BC, 5% BC) at the phylum level. Phyla with an average relative abundance <1% are reported in the “Other” category.

Figure 2

Boxplots describing the trends of chao1-based alpha-diversity for increasing % of colostrum in diets divided per intestinal tract and site. Each dot represents a sample, red lines are the median values of the distributions, the box indicates the 25% and 75% percentiles, and whiskers indicate the minimum/maximum values.

Figure 3

Principal Coordinate Analysis (PCoA) based on the unweighted UniFrac distances for the three diet groups divided per intestinal tract and site. In each plot, each dot represents a sample, colored according to the diet group. Ellipses are the 95% SEM-based confidence intervals, whereas centroids are the average coordinates on all the samples. Coordinates 1 and 3 are represented.

Figure 4

Bubble plots of the relative abundance data (for each intestinal tract and site) over the three groups at all taxonomic levels: CTRL (green), 2.5% BC (blue), and 5% BC (red); phylum (A), class (B), order (C), family (D), and genus (E). Circle size is proportional to the average relative abundance. For each level, only taxa with avg. rel. ab > 1% in at least one of the groups are represented. “Missing” circles are taxa < 1% in that group.