Let’s take it back to basics. The foods and liquids we consume enter our digestive tract, which is essentially a tube that goes from our mouth to our anus. The body secretes enzymes and biochemicals into this tube to break down the food to smaller nutrient components. But, this process, which is called digestion, is also dependent on the help of microbes that live in the gut. Our bodies can then absorb these nutrients and use them for the growth, repair, protection – or survival - of the body. The same is true for people and pets.
The availability of nutrients to the body from foods is called digestibility. This varies with food type, ingredients and source. This is why we may run studies where we carefully measure everything that the pet eats and drinks and also collect the faeces and urine. We can use this information to understand the digestibility of a product. We are looking for a diet that a cat or dog can sufficiently break down to access the nutrients, but not too much as some of the less digestible ingredients are important for gut health (1,2).
There are a vast number of bacteria that live in our guts and they are critical for our health. We know they are essential to help break down and extract some of the nutrients in our food that we cannot do without them. But, as scientists explore the complex interaction between these microscopic organisms and us, they are uncovering evidence to show the range of ways that they impact us. For example, our immune response or allergies (3), mental health
or digestive health (1). This may also be true for our pets. By exploring how the bacterial populations change, we are better able to support the health of our pets through specific ingredients or food.
So why faeces?
As the undigested food leaves the body as faeces it takes with it the bacteria that live in last sections of the intestine. By quickly collecting the faeces and taking it to the laboratory, we can use it for experiments.
One option is for us to use the bugs that are alive in the sample to grow in the laboratory with different ingredients. This can give us an idea as to how the microbes in the digestive tract may respond if the pet was fed that food.
We can also extract the DNA from the sample and use this to find out what bacteria are in the sample as well as their proportions. We can also use genetic analysis to find out more about what the bacteria may be doing (2). For example, some bacteria prefer high fibre ingredients as a food source, whereas others prefer protein or sugars.
The good and the bad
Faeces provide a sample of the contents of the last sections of the digestive tract that is easily and readily available. This means we can collect samples without disrupting the pet’s normal activities. This also means we can collect lots of samples from the same pet over short or long periods of time.
However, there are some limitations. The digestive tract is very long and complex, which means that faeces are only comparable to the last parts of the intestine. Also, the environment in the gut is lower in oxygen compared to air and the temperature of the body is tightly regulated. The bacteria in the intestine are well adapted to these conditions, so when they leave the digestive tract they may not be able to survive and die quickly. This is why we have to transfer the samples to the laboratory as quickly as possible for analysis.
The power of poo
Faeces are a powerful research tool and are widely used in pet and human microbiome research to help us learn more about nutrition and health, the digestive tract and how food is digested. These insights help us develop and improve Mars Petcare products and services in support of our Purpose to create: A Better World for Pets.
Further reading and references
1 Baffoni L. (2018) Probiotics and Prebiotics for the Health of Companion Animals. In: Di Gioia D., Biavati B. (eds) Probiotics and Prebiotics in Animal Health and Food Safety. Springer, Cham
2 Dale Fritsch, Susan Wernimont, Matthew Jackson, Dayakar Badri, Chun-Yen Cochrane, Kathy Gross, Select Dietary Fibers Alter GI Microbiome Composition & Promote Fermentative Metabolism in the Lower Gastrointestinal Tract of Healthy Adult Dogs (P20-044-19), Current Developments in Nutrition, Volume 3, Issue Supplement_1, June 2019, nzz040.P20–044–19
3 Strowig T., Thiemann S., Diefenbach A. (2018) Microbiome and Gut Immunity: Innate Immune Cells. In: Haller D. (eds) The Gut Microbiome in Health and Disease. Springer, Cham