What an Ostrich Can Teach Us About Gut Health
By: Sam Westreich
Tags: Biology, Environment, Science, Farming, Microbiome

When we consider the gut microbiome, we usually think of two things: gut-related diseases, such as irritable bowel syndrome (IBS), or probiotic supplements.

(At least, this is what I think about, as a microbiome scientist. Most people that I speak with are not microbiome scientists, and they just give me weird looks when I begin enthusiastically speaking about the gut microbiome.)

But the gut microbiome — the collection of trillions of bacteria, comprised of hundreds of different species, all living in an uneasy balance with each other inside our intestinal tract — isn’t just for humans. Dogs, cats, mice, cattle, and just about every other animal on the planet has their own gut microbiome.

Because we generally care more about curing irritable bowels in people, rather than in mice, most studies of the gut microbiome tend to focus on humans.

Recently, however, researchers in Sweden published a paper looking at the impact of the gut microbiome on juvenile mortality — in ostriches.

Here’s what they found.

Not Only the Good Ostriches Die Young

An ostrich can live for a very long time — if it makes it past childhood.

Most adult ostriches live for at least 40–45 years, with some making it as old as 75 years. This is quite long-lived; ducks and chickens will live 5–10 years and a goose lives 10–15 years, in comparison. (Of course, some other birds, such as parrots, can live even longer — up to 75 years in captivity.)

However, many ostriches don’t make it to even their first birthday. In one study of more than 2,500 chicks, more than three-quarters of them — 78% — didn’t even survive 90 days beyond hatching!

This is a concern for us, not just because it’s sad to know that most baby ostriches don’t make it, but because ostrich farms are a profitable business industry. Ostriches are highly profitable, and have several advantages over raising beef cattle or other birds:

They adapt well and need little shade or protection from the elements;

Unlike chickens, ostriches are capable of aggressively defending themselves from predators;

The meat, eggs, skin (for leather), and feathers of ostriches are all sold for excellent prices;

Ostriches produce more meat for the amount of consumed resources (higher efficiency) than cattle.

If you’re a farmer, a herd of ostriches could be big bucks — if you can keep too many chicks from dying.

Experiments have looked at different ways of incubating and raising ostriches. A more intensive and nurturing system produced fewer dead birds, but it’s not a perfect solution.

So what kills baby ostriches? One possibility — it could be related to their gut microbiomes.

Is an Out-of-Whack Ostrich Gut Linked to Chick Death?

In the research paper, Videvall and her team used a method called 16S rRNA sequencing to look at the composition of different bacteria in the guts of baby ostriches at various time points.

16S rRNA sequencing is a bit like scanning barcodes at a grocery-store checkout line; it looks at a specific gene, called the 16S subunit, in order to identify different bacteria. Each family of bacteria has slight variations in its 16S gene that differentiates it from other types of bacteria. By using computers to match the 16S gene of all the bacteria from a sample to a reference, we can quickly determine which bacteria are present in a sample.

“You’re taking my poop… for WHAT?!?” Photo by Krzysztof Niewolny on Unsplash

The researchers used this 16S sequencing method to take “snapshots” of the gut microbiomes of baby ostriches as they grew — and when they died, from autopsies of the dead birds. They then compared the microbiomes of the surviving ostriches with those of the chicks that died during the first 90 days of life.

What did they find?

Overall, individual birds who passed away had drastically reduced microbe diversity — that is, there were way fewer species of bacteria in their guts. If the healthy birds had an Amazon rainforest of different species thriving in their guts, the sick birds had a cornfield — far fewer different organisms.

Additionally, some species of bacteria seemed to be more prevalent in sick birds, while other species were more present in the healthy birds. It’s not just how many bacteria were present, but the right ones, instead of the wrong ones, seemed to also play a role.

One interesting conclusion that the authors found was not from the birds directly — but from their environment. How did the bacteria that seemed connected with early death get into the birds?

Sequencing of the environment showed that they didn’t come from the food, water, or soil where the birds were raised. Instead, it seemed like small numbers of these “bad bacteria” were in the baby birds from the beginning.

In the healthy birds, other species crowded out these bad bacteria so that they couldn’t take over. But in the sick birds, the lack of diversity let the bad bacteria proliferate, taking over that gut environment.

There’s Always More to Study

Of course, this study isn’t putting the nail in the coffin for the question of why so many baby ostriches die. There are still a bunch of outstanding questions, including:

What mechanism makes some of these bacteria bad, and what’s different in the good bacteria?

Can we reduce the loss of diversity in sick ostrich chicks?

Is this causative? In other words, we see low gut diversity in the sick birds, but is that what’s responsible for their deaths?

When and how would we intervene to restore a more diverse gut microbiome with healthy bacterial species?

These questions aren’t just relevant to ostriches — we have the same questions with many of the bacteria that we see in human gut microbiomes. We’re working on answers, but they’re not present yet.

Interestingly, many of the “bad bacteria” seen in the low-diversity guts of sick ostrich chicks are closely related to bacteria that are found in humans — and that are associated with negative outcomes. Perhaps if we can better figure out how to understand and improve the human gut, we can do the same for ostriches!