Orally administered ovine serum immunoglobulins modulate the intestinal levels of Lactobacillus and enterobacteria in the growing rat.

ABSTRACT

The aim was to determine whether orally administered ovine serum immunoglobulins modulate the gut microbiota in the growing rat. Thirty Sprague-Dawley male rats were used in a 21-d study and fed either a basal control diet (control; no immunoglobulin) or a similar diet containing freeze-dried ovine immunoglobulin (ovine Ig) with 15 individually fed rats per diet. Bacterial DNA isolated from ileal and colonic digesta were subjected to PCR-denaturing gradient gel electrophoresis (PCR-DGGE). In the ileum, the DGGE band number and diversity index were greater (P < 0.05) for rats fed the ovine Ig than those fed the control diet. The DNA sequencing of a selected DGGE band in the ovine Ig-fed rats revealed 99% similarity to the Lactobacillus strains. The quantitative PCR data revealed that supplementation of the diet with the ovine Ig fraction supported the growth of Lactobacillus and conversely decreased the number of enterobacteria in ileal and colonic digesta. Inclusion of the ovine Ig fraction led to a greater (P < 0.05) ratio for total Lactobacillus to total bacteria and total Lactobacillus to enterobacteria. The results from the present study show that dietary supplementation with ovine Ig may alter the intestinal environment by a specific enrichment of Lactobacillus strains and depletion of enterobacteria.