A ‘good doer’ describes a type of horse/pony that seems to live on fresh air but is prone to multiple health issues related to metabolism. The ‘good doer’ tends to clash with the modern management system to the extent that owners find them often almost impossible to manage at certain times of the year, particularly spring and autumn.
Health issues can cause the good doer to spend long periods in the stable or on a bare patch because exposure to pasture or certain foods can exacerbate any symptoms associated with metabolism.
Often the ‘good doer’ is a native pony, originally bred to survive a mountain or moorland environment, where he would have access to, what we would describe as low-quality forage in the winter months (which may account for almost half the year in a period extending from the beginning of November until the end of March and often into May).
As a ‘good doer’ he possesses several important survival mechanisms described in the post ‘please don’t over-rug this winter’. https://www.facebook.com/groups/1862115997153052
How the Microbiome Helps the Host Survive
Now new gene technology has helped to identify an extra crucial mechanism that has developed together with the host over hundreds of years, to help him survive and adapt to long winter months.
Two of the most popular of the UK’s native ponies have evolved out of two of the UK’s bleakest environments.
The Shetland pony was bred to survive on a diet foraged from blanket bogs- containing heather, cotton grass, crowberry and bilberry, sphagnum moss plus access to the aquatic plants of freshwater lochs and marshes.
The Welsh Mountain pony was bred to thrive and survive on the alpine meadowlands of Snowdonia, the breed is thought to originate in Roman times and has been ‘improved’ by the addition of arabian blood (another tough survivalist originating from the desert).
How Modern Management Systems Have Changed
Over the last 40 years, these two native ponies (along with the others from the UK) now often receive more calories than they require, eat from fertilised monoculture pastureland (97% of the type of grazing needed to sustain ‘good doer’ health has gone), and are protected from extreme weather conditions with stabling and rugs.
Mixed meadows provide high levels of antioxidants from low- quality fibrous forbs and herbs.
Since 2016 we have been analysing the gut microbial communities of many different populations of horses and ponies using genomic sequencing and it is now possible to identify the enterotype of some, including that of the ‘good doer’. We can also identify the changes and probable consequences to the microbiome from an alteration of living conditions.
What is an Enterotype?
The gut microbiome is a vast and complex community, in the horse it is common to see between 1,000 and 1,500 distinct species. Many of these species are transient and pass through the microbiome from the soil and plants the horse eats, and others form part of a permanent core.
The make-up of the microbial community differs between horses, no two are the same, and the gut microbiome has approx. 100 times as many genes as the equine genome (estimated at 20,000). The main duty of the microbiome is to degrade indigestible dietary polysaccharides and make, SCFA’s, amino acids and vitamins.
The term enterotype was proposed in 2011 when a researcher analysed 33 samples from different human populations and found that they could be divided into three distinct types i.e. predominantly Bacteroides (enterotype 1), Prevotella (enterotype 2), and Ruminococcus (enterotype 3).
Similarly, it is possible to define enterotypes in populations of horses, thoroughbreds have an enterotype that is predominantly clostridium.
The microbiome can change rapidly in response to dietary, environmental, and medical interventions, these changes in the short term do not alter the enterotype permanently though the enterotype will change over a longer period, as a process of evolution.
Native pony enterotype
The Native pony enterotype is represented by higher levels of treponema, prevotella and verrucomicrobiales, (an increase in verrucomicrobia has been associated with laminitis).
Alternatively, the Thoroughbred enterotype is represented by clostridium, sutterella, verrucomicrobiales (an increase in verrucomicrobia in a thoroughbred racehorse is a marker of fitness and performance).
As our population database has grown and with the benefit of an AI platform it has been possible to identify enterotypes based on breed. The Welsh Mountain, Shetland and Carneddau ponies share a similar microbial profile. This is interesting because the Welsh and Shetland samples analysed, were from ponies no longer grazing on moorland, whilst the Carneddau ponies remain in their native environment (Snowdonia National Park) which has been their home for hundreds of years.
Dysbiosis
Though the ponies all share an enterotype there are differences between them relating to negative impacts or dysbiosis.
In a paper published in 2020, Garber et al., identified four changes in the microbial population that had a negative impact on the microbiome. When we looked further into the datasets of all 3 breeds of ponies, the ‘modern living’ Welsh and Shetland ponies had 3 out of four of the listed differences whilst the Carneddau didn’t have any at all.
Listed changes
1 A decrease in microbial diversity and richness
2 A decrease in Lachnospiracea and Ruminococcaceae (gut homeostasis)
3 An increase in Lactobacillus and Streptococcus
4 A decrease in lactic acid utilising bacteria.
5 A decrease in butyrate-producing bacteria with anti-inflammatory properties.
All of these negative impacts will make the host more prone to a range of diseases including laminitis and EMS see references at the bottom of the article.
How do the bacteria within the enterotype extract more nutrients from low grade food items.
In a published paper (Hongjin Liu et al 2022) examined the enterotype of the Tibetan wild asses (Equus kiang) from the Qinghai-Tibet Plateau, the ass has a similar digestive system to the horse but is even more efficient at digesting and extracting nutrients from indigestible fibre than the horse.
They identified a similar enterotype to the native ponies defined by the presence of Treponema, Prevotella and Verrucomicrobia. (the same enterotype as the uk native ponies). They also found a microbiome with high microbial diversity, supporting the digestion of forage and prolific short-chain fatty acid production.
The researchers discovered that when forage was sparse (winter months or drought) the wild asses made metagenomic alterations to target the use of nitrogen and to further increase the production of short-chain fatty acids. Bacteria species such as cellulolytic strains (Prevotella ruminicola, Ruminococcus flavefaciens, Ruminococcus albus, Butyrivibrio fibrisolvens, and Ruminobacter amylophilus) were higher, plus an increase in carbohydrate metabolism genes (GH43, GH3, GH31, GH5, and GH10) and enzymes (β-glucosidase, xylanase, and β-xylosidase, etc).
They concluded that it is the gut microbiota can improve the adaptability of the host through increased digestion and harvesting of nutrients when food is sparse.
Conclusions
The native pony enterotype Treponema, Prevotella, Verrucomicrobia is extremely efficient at extracting nutrients from food. The host has the genetic capacity to adapt further to process woody fibrous types of material. Removal from a wide, complex, diverse, high fibre diet may cause negative impacts on the microbiome, the most important of the negative impacts is a loss of diversity.
Coleman, M. C., Whitfield-Cargile, C. M., Madrigal, R. G., & Cohen, N. D. (2019). Comparison of the microbiome, metabolome, and lipidome of obese and non-obese horses. PLoS One, 14(4), e0215918.
Biddle, A. S., Tomb, J. F., & Fan, Z. (2018). Microbiome and blood analyte differences point to community and metabolic signatures in lean and obese horses. Frontiers in veterinary science, 5, 225.
Garber, A., Hastie, P., & Murray, J. A. (2020). Factors influencing equine gut microbiota: Current knowledge. Journal of Equine Veterinary Science, 88, 102943.