Evaluation of intestinal development and the bacterial community in the gastrointestinal tract of poultry

Abstract

With advances in molecular tools to identify bacteria and the growing concern about antibiotic use in livestock feeds, researchers have focused on understanding the normal bacterial community in the gastrointestinal tract (GIT) of animals and how the bacterial community can be changed to benefit the animal. Experiments evaluated the development of the GIT and the bacterial community of broilers under various conditions. In the first experiments when chicks were fed from 0 to 21 d of age, the impact of different diets with alternative protein sources and crystalline amino acids on the development of the GIT were evaluated. The bacterial populations were different due to diet even when no differences in intestinal development manifested, but when a diet was fed that also affected intestinal development, a clear separation in the bacterial populations of birds fed a corn-soybean meal or a crystalline amino acid diet appeared. When male and female broilers received the same diet, there was no difference in intestinal development between the males and females, but the bacterial populations separated into 2 clusters based on gender. When evaluating different genetic lines of broilers, the multipurpose broilers were found to have the highest body weight gain and fastest rate of GIT development, followed by the high yield and the Athens Canadian Random Bred (1957 line of broiler) broilers. The bacterial populations grouped together between the high yield and multipurpose broilers (modern lines), while the bacterial community of the Athens Canadian Random Bred broilers clustered separately from the modern genetic lines. When novel species of Bacteroidaceae and Clostridia served as a possible probiotic, no overall difference in performance, carcass yield, intestinal development, and bacterial community was observed. But during early stages of development (0 to 3 d), broilers inoculated with the novel combination of Bacteroidaceae and Clostridia had increased villi height and goblet cell concentration. In all experiments, as broilers aged and developed, a change in the bacterial community occurred. When the rate of GIT development plateaued, the bacterial populations stabilized and became less diverse.