Managing the gut microbial populations: From science to practice

Colonization and succession of the gastrointestinal microbiota in avian species is not well characterized; however, as in other systems, it is recognized that the microbiota influences the health and production efficiency of poultry. Numerous studies have revealed that the gut microbiota of commercial poultry flocks is highly variable within and between flocks. We believe this is influenced by the initial colonizers of the gastrointestinal tract, as the small intestinal microbiota between producers differ significantly in poults and chicks at day-of-hatch. Our data suggests that horizontal transmission from the environment is greater than vertical transmission in poultry production due to common commercial management practices. We have shown that successional changes in the small intestinal microbiota start in ovo and are affected by management practices such as disinfection of the setter and the hatcher as well as administration of antibiotics and/or vaccines in ovo leading to hatchery-specific bacterial populations. The early establishment of lactic acid bacteria essential for stabilizing intestinal homeostasis, digestion and nutrient absorption, and nurturing mucosal conditions for immunological protection is disrupted in commercial birds. In addition, our research has documented significant populations of avian pathogenic Escherichia coli (APEC) in broiler chicks at the day of hatch. APEC is a causative agent for colibacillosis in birds in the form of airsacculitis, cellulitis, pericarditis, or perihepatitis. A high population of APEC can disrupt gastrointestinal homeostatis in the young bird and impact early growth and performance. If left unchecked, these isolates can translocate to the blood stream and cause colibacillosis.

In order to, promote colonization by beneficial bacteria and reduce the levels of APEC, without the use of antibiotics, a probiotic was developed comprised of two lactic acid bacteria selected for their immunomodulatory capabilities and two Bacillus strains that produced secondary metabolites inhibitory to APEC strains. This probiotic was administered to chicks in a single dose at the hatchery. A study comparing the probiotic against the antibiotic gentamycin, indicated that both the probiotic and the antibiotic reduced APEC levels in two-week old broilers compared to untreated birds. A second study showed a reduction in levels of APEC at day 7 as well as more uniform flocks as the coefficient of variability at harvest was reduced. The probiotic is therefore an effective alternative for antibiotics to establish a healthy microbiota and control APEC when applied at the hatchery.

Abstract presented at the 3rd International Symposium on Alternatives to Antibiotics 2019.