What is a hen's gut microbiome?
“Healthy guts make happy hens”
What is a hen's gut microbiome?
A microbiome is the collection of organisms in a particular environment. Therefore, a hen's gut microbiome is the collection of different microorganisms, the microbiota, inside her gut. The microbes making up this microbiota consist of different types of bacteria, viruses, fungi and protozoa. The number and type of different organisms differs from one part of the gut to another. For example, microbes in the caecum are responsible for fermentation.
You may think it's only the skin of a bird which contacts the outside world, but actually their intestines are constantly exposed to the outside world too. Intestines are designed to maximise absorption of nutrients from the gut into the blood stream by having a very large surface area despite their relative small size. There is only a thin layer between the food inside and the blood stream within the intestinal walls. This creates a huge surface area inside the bird that is continuously exposed to the outside environment, and at risk of invasion. The intestines are exposed to food and treats, or microbes, molecules and compounds present on surfaces that the hens peck on and to feathers that they groom.
What affects the gut microbiome in hens?
The composition of a hens gut microbiome changes depending on breed, age, diet and even the environment that they live in. For example, hens who range outside will develop a different microbiome after prolonged periods of housing. This is one way that hens adapt to their environment.
What types of bacteria can be found within the gut of a healthy hen?
A normal hen gut microbiome is dominated by the following types of bacteria - Proteobacteria, Firmicutes, Bacteroidetes, Fusobacteria, and Actinobacteria.
Does the bird "pay" to have a microbiome?
Yes. Microbes need energy and protein, which they take from the food ingested at a cost to the bird. Therefore, it is essential to ensure the bird is getting the most work out of its microbiota at the lowest cost to itself by encouraging a healthy microbiome.
What does a healthy microbiome do?
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Bacteria in the caecum ferment undigestible substances which the bird cannot digest using the enzymes The enzymes ferment these undigestible substances, like some plant material fibres, and produce molecules the bird can absorb and use. Examples are short chain fatty acids (acetate, propionate, and butyrate), organic acids (e.g. lactic acid) and some vitamins (Vitamin K and some B Vitamins).
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Gut microbiota attach to the lining of the intestines. Healthy gut microbes make it difficult for pathogens to attach and invade then hen, thus preventing disease simply by reducing the space available for invasion.
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Healthy gut bacteria compete for food with bacteria which can cause illness in humans, such as Salmonella and Campylobacter, making it harder for these pathogens to flourish inside the bird.
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The presence of microbes stimulates the hen to protect itself against invasion. The hen's intestine produces a mucus barrier, which protects the bird from invasion by pathogenic microbes.
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Some short chain fatty acids produced by gut bacteria have antibacterial properties. Bacteria produce these to protect themselves from other bacteria, but their production also helps protect the bird from pathogens.
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Microbes in the gut can communicate with the host's intestinal cells by producing molecules that can communicate between them, including short chain fatty acids.
