Pioneer colonizers: Bacteria that alter the chicken intestinal morphology and development of the microbiota

Abstract

Microbes commonly administered to chickens facilitate development of a beneficial microbiome that improves gut function, feed conversion and reduces pathogen colonization. Competitive exclusion products, derived from the cecal contents of hens and shown to reduce Salmonella colonization in chicks, possess important pioneer-colonizing bacteria needed for proper intestinal development and animal growth. We hypothesized that inoculation of these pioneer-colonizing bacteria to day of hatch chicks would enhance the development of their intestinal anatomy and microbiome. A competitive exclusion product was administered to broiler chickens, in their drinking water, at day of hatch, and its impact on intestinal morphometrics, intestinal microbiome, and production parameters, was assessed relative to a control, no treatment group. 16S rRNA gene, terminal restriction fragment length polymorphism (T-RFLP) was used to assess ileal community composition. The competitive exclusion product, administered on day of hatch, increased villus height, villus height/width ratio and goblet cell production ∼1.25-fold and expression of enterocyte sugar transporters 1.25 to 1.5-fold in chickens at 3 days of age, compared to the control group. As a next step, chicks were inoculated with a defined formulation, containing Bacteroidia and Clostridia representing pioneer-colonizing bacteria of the two major bacterial phyla present in the competitive exclusion product. The defined formulation, containing both groups of bacteria, were shown, dependent on age, to improve villus height (jejunum: 1.14 to 1.46-fold; ileum: 1.17-fold), goblet cell numbers (ileum 1.32 to 2.51-fold), and feed efficiency (1.18-fold, day 1) while decreasing Lactobacillus ileal abundance by one-third to half in birds at 16 and 42 days of age, respectively; compared to the phosphate buffered saline treatment group. Therefore, specific probiotic formulations containing pioneer colonizing species can provide benefits in intestinal development, feed efficiency and body weight gain.

Keywords: anaerobes; feed efficiency; intestinal development; microbiome; performance.

FIGURE 1

Relative expression of glucose transporters Glut2, Glut5 and SGLT1 (p < 0.05) in the small intestine of 3 d old broiler chickens receiving a competitive exclusion product (Aviguard^®) or no treatment (control) on the day of hatch. Relative gene expression was determined using the 2^−ΔΔCT method. GAPDH was used to normalize gene expression for targeted genes.

FIGURE 2

Composition of the ileal bacterial community of chicks administered Aviguard^® (panel (B)) or no treatment (control, Panel (A) on day of hatch as determined by 16S rRNA T-RFLP at 3, 7, 14, 21, 28 and 49 days of age.

FIGURE 3

Shannon’s H diversity index of samples collected from the ileal bacterial community of chicken from the control (no treatment) or birds administered a competitive exclusion product (Aviguard^®) at day of hatch. Samples were collected at 3, 7, 14, 21, 28 and 49 days of age.

FIGURE 4

Composition of the small intestine bacterial community of chicks administered pioneer colonizers on day of hatch as determined by 16 S rRNA T-RFLP from samples collected from the jejunum (A–D) and ileum (E–H) of chickens from the phosphate buffered saline control group (A, E), Romboutsia lituseburense and Escherichia coli cocktail (B, F), Parabacteroides distasonis, Bacteroides salyersiae, Phocaeicola dorei, and Escherichia coli cocktail (C, G), P. distasonis, B. salyersiae, P. dorei, R. lituseburense and E. coli cocktail (D, H).