Gut Reactions: Exploring The Microbiome

Tuesday, September 26, 2023

Tiny particles pack a punch.

By Geoff Geddes

The world offers much to marvel at: Childbirth; space travel; a massive group of fungi. The last one might sound out of place, but how else to describe trillions of tiny organisms working in concert?

These collections of bacteria, viruses, fungi, and many other single-cell germs are called microbiota, or microbiome when referring to the organisms and their genes. They exist throughout the body of humans and animals to support a range of functions. Some of these roles are creating vitamins and amino acids, breaking down food compounds that could be toxic, stimulating the immune system, and competing with bad bacteria.

Of particular interest to the pork sector today is the gut microbiome and maximizing its potential to benefit pigs and producers.

With the growing demand for food on a global level, anything that softens the blow of feed costs, disease and performance issues is welcomed by industry to enhance yield, pork quality and profitability. In part, this explains the desire for greater study of the pig's gut microbiome and its relationship to animal health and nutrition.

"A key focus for science is the role of the gut microbiome in pig health and performance," says Dr. Vahab Farzan, research scientist in the Ontario Veterinary College at the University of Guelph (UoG).

Strive to thrive

With the huge expense posed by feed, especially at the grower-finisher stage, keeping pigs healthy and thriving is critical to protecting the producer's investment. That can be a challenge at weaning, as the animals transition from a safe, secure environment with their mother to a mixed pen and different diet. For some, it can be like moving from a five-star hotel to a hostel, and the resulting stress may alter the gut microbiome and invite bacteria to bring disease.

"One of the most damaging diseases at this stage is postweaning diarrhea (PWD), mostly caused by enterotoxigenic E. coli," says Farzan. "It may wreak havoc on a farm and is difficult to combat. Pigs at that age often have immature immune systems that don't respond to vaccines, and in-feed additives like high level of zinc oxide aimed at preventing PWD can harm the environment."

Fortunately, there is some evidence that the gut microbiome can boost vaccine effectiveness in certain cases.

Though science hasn't pinpointed the exact mechanism at work, "we are seeing an indication that the microbiome could improve immune response," says Dr. Matheus Costa. Dr. Costa is an assistant professor, Large Animal Clinical Sciences at the Western College of Veterinary Medicine, University of Saskatchewan.

You really ARE what you eat

To realize its full potential, the microbiome may be assisted to thrive during the challenges that modern production systems face. For example, diet heavily influences the microbiome composition and function, and weaning piglets means they go from a liquid to a solid diet.

"By allowing pigs to eat solid food before weaning, we help them mature their microbiome sooner, making it more stable and resilient against the challenges ahead," says Costa. "Taking this route gives them a head start and renders them less susceptible to disease during that critical period."

The benefits of such an approach reinforce the need to transition what pigs consume prior to weaning.

As many yogurt eaters would attest, probiotics, composed of so-called good bacteria that exist in the body, are another means of nurturing the gut microbiome. Humans and animals have both good and bad bacteria, and probiotics can help restore the balance between the two when disruption occurs.

"Factors like stress and disease may harm that delicate balance and allow the bad bacteria to dominate," says Farzan. "Through work on promoting good bacteria in the gut, science looks to even the odds and perhaps even turn them in favour of the beneficial type of bacteria. This could lead to performance enhancement in pigs through things like better growth and improved feed conversion."

On another front, with science exploring the genetic basis of disease resistance, it sees the microbiome as playing a major part.

"As we study these microbial communities more closely, we're working towards selecting for pigs that naturally grow better and fare better because of their microbiome," says Dr. Brandon Lillie, associate professor/chair, Department of Pathobiology, Ontario Veterinary College, University of Guelph. "Is this something we could add to genetic selection parameters in addition to other elements already included for swine production?"

Multiple choices

Of course, if this stuff was easy, we'd all be dabbling in genetics. Selecting for certain traits involves SNPs (also known as single nucleotide polymorphisms). An SNP is the most common type of genetic variation within a species, but these differences don't occur in a vacuum. When science tries to enhance one trait, such as marbling, it can have a negative effect on another trait such as fetal development.

"It often comes down to a cost-benefit analysis," says Lillie. "Does the improvement in the microbiome, for example, justify sacrificing a bit of lean yield? What is mathematically better for the producer in the end?"

While our knowledge of the microbiome is growing daily, there is still much to learn and explore. Scientists are examining the relationship between the sow's and piglet's microbiome, and how the latter changes over time. They also want to get a clearer picture of how those changes relate to pig health and performance later in life.

Daring to be different

Another area of interest is diversity and its impact on the functioning of the microbiome. As with your investments, the goal is having enough diversity to bring stability, but not so much as to spark chaos.

"Diversity of content in the microbiome is a very important element," says Farzan. "At birth, piglets have limited diversity. This starts to change as they are exposed to the sow and the environment in which they live. Though that increase in diversity is a good thing, we don't want anarchy."

With each bit of information gleaned about the microbiome, more questions arise, underlining the need to continually add to our knowledge base in this area. For example, science talks about good and bad bacteria, yet it's not always that simple.

"A proper understanding of the bacterial content in the gut is vital," says Farzan. "We think of E. coli (a common bacteria residing in the gut) as harmful because some strains cause serious infections. Other bacterial strains, however, perform positive acts, like helping to digest food. Those good bacteria are ones we want to support and foster so they can occupy a 'seat' at the table and leave their bad counterparts without a place to sit."

There is also the matter of timing. What is the ideal stage to intervene in the pig's microbiome? Should it take place at weaning or at an earlier age?

Thanks to advances in technology, industry is finding even more avenues of exploration.

Overlooked and underrated

"Some gut bacteria appear with less frequency or abundance, yet they can still play a key role," says Farzan. "The Conservatives and Liberals constantly battle it out, while the NDP never gets to govern in Ottawa. The NDP may fail to gain a majority, but the party serves a clear purpose and may even determine the government at times."

A decade ago, these bacteria went undetected because of their sparsity. Fast forward 10 years, and genetic sequencing makes it possible to pinpoint them and, one day, determine their value to the microbiome.

Like any facet of life, the microbiome involves both possibilities and limitations. Just as its dynamic nature may present roadblocks to discovery, its essence is cause for hope.

"The biggest misconception about the microbiome is that it's stable throughout life," says Costa. "If you took a swab from a pig's mouth every day, the microbiome would look different each time, as transient members come and go. That being said, there is always a core portion that doesn't change very much, and it is likely this part that is responsible for some of the health benefits in pigs."

The challenge of change

It is also worth noting that the microbiome is not easily modulated. Antimicrobials in large, regular doses could spark rapid change, but that is not feasible as countries look to limit antibiotic use. Other options include probiotics (microorganisms that help shape the makeup and function of gut bacteria), prebiotics (nutrients which are used by good bacteria and/or alter the gut condition in favor of good bacteria), and postbiotics (bioactive compounds that are essentially the products of probiotic bacteria, yet offer various health benefits to the body).

"The various '-biotics' can lead to alterations; however, it takes a concerted effort for this approach to result in long term change," says Costa. "This is similar to humans consuming yogurt: You can't just eat it one morning and expect it to make you regular. It is the same with pigs, where things like probiotics must be taken on a daily basis. You must be constantly seeding the field so that whatever needs to grow, will grow."

According to experts like Costa, science is just starting to grasp what the microbiome is all about.

Dialed in

"Compared to other fields like oncology or vaccines, we are merely scratching the surface right now with the microbiome. It includes so many functions and consequences, so you turn one dial and something happens, then you turn another dial and 200,000 things change."

Against this backdrop, producers, veterinarians and swine scientists should guard against seeing the microbiome as a cure-all. Instead, they are encouraged to consider their unique situation and what they're trying to accomplish. From there, it comes down to the old cliché that "knowledge is power." Oh, and that other cliché: "patience is a virtue."

"Science is examining a wide array of strategies for protecting pigs and investments," says Costa. "The microbiome shows promise, but we shouldn't view it as the Holy Grail. Your approach should reflect the challenges you face in your operation."

If pigs are receiving enough feed and water, a balanced diet, and sufficient housing, their microbiome might evolve and mature properly on its own.

"We keep trying to modify so many aspects of the business, and sometimes we create problems for ourselves, yet it's not always necessary," says Costa. "Wild boars don't wean until 60 days of age; with piglets, we do it at 21 days."

In the competitive pork sector, producers are used to doing their homework before fully adopting something new, and the same applies with the microbiome.

"Tools such as probiotics have their critics and supporters, and there is research to support both sides at the moment," says Costa. "Are they a waste of money or a good investment? If I was a producer, before adopting any approach, I would make sure to collect data that shows this approach will make a difference in my specific case."

Just as you wouldn't rush out and buy a certain tractor just because your neighbour has it (well, hopefully not), Costa suggests running your own test on-farm.

"You don't want to spend money on a particular probiotic, only to discover that your pigs already have plenty of that material in their gut. Instead, you could work with your veterinarian or nutritionist: With your next batch of pigs, feed the probiotic to only one half. If that half grows faster, has less diarrhea or doesn't develop skin disease, you may be on the right track.

"Right now, there is a hundred times more effort being expended on human health compared to pig health, and it was only recently that the first official microbiome treatment was licensed for use in people," says Costa.

"Don't get overly excited, and remember that there is a lot of information on the microbiome out there. If it is an area of interest for you, take the time to educate yourself, critically review any information and be ready when opportunity knocks."

Given the ultimate potential of the microbiome, it should be time well spent. BP