“I really think to be able to manipulate the microbiota you need to go to the early life of these birds,” Alexandra Smith, Ph.D., manager of microbial ecology and genetics, Arm and Hammer, stated during the Poultry Tech Webinar Series on December 2. Early in the bird’s life, the microbiota succession (the amount of bacterial diversity) is lower, meaning that it is easier to manipulate compared to later in the bird’s life. This leads to a more mature, stable gut health status for younger birds.

Establishing the adult poultry microbiome without the hen

In nature, chicks are hatched, then spend time with their mothers. This helps them establish a mature microbiome quickly, leading to health benefits early on such as resistance to pathogens or the ability to biosynthesize vitamins and amino acids. In modern systems, the eggs are removed from mothers and cleaned, then delivered to farms without adult birds. This means that the bacteria the chick is exposed to first after hatch will most likely establish in the gut.

While some practices expose chicks to bacteria through built-up litter from previous flocks to help establish the microbiome, it is critical that the previous flock was healthy. This situation presents an issue to the modern poultry industry.

The solution

“Improving the microbial succession, I believe is very important because as soon as you get a stable microbiota in the bird, the microbiota can perform functions. Also, you're less likely to get pathogens coming in with mature microbiota,” explained Smith. “When the microbiota is still sort of in flux. It's easier for pathogens to come in and colonize.”


Smith explained different bacteria will create a different gut microbiota in the bird, and it matters which bacteria is first introduced into the gut first. “Our studies have determined that the main effect of what colonizes these birds is what happens at the hatchery. There is some effect from the birds but we're not sure if that is direct transmission of bacteria directly from the hen to the chick through the egg, or if it has to do more with the immune status of the bird.”

In one study Smith presented, a group of chicks were inoculated with adult cecal contents and another group was not, all prior to hatch. It was found that microbiota development of a healthy adult microbiome was accelerated in the chicks that were given the cecal contents.

Smith insisted that even though microbiota succession can be increased, the type of bacteria present in any bird’s gut will be hard to predict. In studies performed by her lab, Smith showed how problematic it is to determine what a healthy microbiota is and what bacteria will be found in it. Significant differences in gut bacteria were found between birds of the same age, in the same environment, and consuming the same feed. However, if the host is healthy, then we shouldn’t care which bacteria it is. This is because the host is going to have predominant bacteria that are specifically suited to it and providing health benefits needed.