Host-specificity of intestinal microbiota of broiler chickens

Genetic selection for body weight gain in the poultry industry resulted in a large increase in growth rate and efficiency of broilers. This selection possibly modified the development and the function of digestive tract, as well immunological properties of broilers, potentially changing their permittivity to microbial colonization. The present study aimed investigate the temporal development of intestinal microbiota in fast (Cobb500^TM) or slow-growing (Label Rouge) broilers. Both strains were created in thermoneutral temperature, and received the same diet (ad libitum) formulated with nutritional requirements of Rostagno et al. (2011). At 21, 28 and 42 days of age, samples from mucosa and content of ileum and from cecum were collected. Metagenomics' DNA were extracted from that, and specific groups analyzed by qPCR method. The copy numbers for Bacteroidales was 6 x 10¹⁰ and 1 x 10⁸ for fast and slow-growing birds, respectively, which means a difference of 630 times, suggesting that the abundance of this group is host-specific. At ileum mucosa, the increase of age leads to: increase in the 16S rRNA gene copy numbers for Lactobacillus and Clostridium cluster IV (P < 0.05) for Cobb broilers, and of Lactobacillus, Enterococcus (P < 0.05) and Clostridium cluster XIV (P < 0.10) for Label Rouge broilers. For ileum content, we found decrease in Enterococcus (P < 0.05) for fast-growing and increase in Enterococcus, Clostridium cluster IV and Clostridium cluster XIV (P < 0.05) counts for slow-growing broilers. At cecum, with increase of age, was detected increase of Lactobacillus, Clostridium cluster XIV and Bacteroidales (P < 0.05) and decrease of Enterobacteriaceae and Enterococcus (P < 0.05) for Cobb strain; decrease in Lactobacillus (P < 0.05), Enterobacteriaceae (P < 0.10) and Clostridium cluster XIV (P < 0.05) were found for Label Rouge broilers. Knowing that host can exert genetic selection pressure on the intestinal microbiome, mainly via immune system, our data suggest co-selection of specific groups. In conclusion, temporal modifications found in intestinal microbiota of broilers is different between strains, showing that genetic host is determinant to intestinal colonization.