7 minute read
Foran Equine advertorial
Gut instinct
Written by: Nichola Reynolds, MSc. Nutritionist at Foran Equine and Connolly’s Red Mills
ANYONE WITH A vested interest in optimising the equine athlete’s health, welfare, and performance will be aware of the important role that the hindgut plays in all these things, and how its functioning can impact everything from behaviour and performance, right through to immune health.
Over recent years advancing research techniques have allowed a better understanding of how different management regimes can affect the hindgut and its resident microbial population (the microbiome).
Owners and trainers have seen first-hand how specific improvements to management regimes can improve hindgut health and in turn have a direct impact on condition and performance.
What is the microbiome?
The equine microbiome is a population of micro-organisms that colonise the hindgut; it is made up of bacteria, fungi, and protozoa.
This population of microbes has many functions, but primarily they are there to ferment (digest) fibre through fermentation. A healthy, balanced microbiome is essential for efficient fibre digestion and utilisation.
Over recent years we have gained a better understanding of how critical the microbiome is to a healthy immune system, balancedtemperament, and overall wellbeing.
Research in the human field has already shown connections between our microbiome and its relationship with performance, recovery, long-term health, emotional well-being, and mental clarity.
The healthy and balanced microbiome that we are striving for in our horses relies on a varied and plentiful supply of fibre from forages, including different grasses and conserved forages, such as hay or haylage.
Horses naturally forage either in the wild or some domesticated settings. This natural foraging provides a vast array of plant material to satisfy this internal population of microbes and ensures that the fibrolytic, or fibre loving bacteria, remain the dominant microbe.
This results in a robust microbiome, which is more capable of resisting certain disruptions, for instance those caused by management changes and environmental stressors, more readily.
For horses where their microbiome is less healthy and more unstable, certain management factors could potentially lead to a much more damaging disruption and thus increased risk of problems including hindgut acidosis.
What is hindgut acidosis?
Put simply hindgut acidosis occurs when the pH (see Box 1) in the hindgut is shifted down the scale to less than pH 6.
This change in pH is usually due to a shift in the bacterial population in favour of more lactic acid producing bacteria as well as an increase in the production of Volatile Fatty Acids (VFAs).
The change may occur suddenly and cause acute problems, or it may be more of a repeated insult causing a more chronic set of problems, such as:
• Decreased forage utilization
• Changes to body condition (usually a loss of condition)
• Changes to behaviour and demeanour
• Intermittent discomfort
• Inappetence
• Colic
• Decreased absorption of nutrients
• Laminitis
• Diarrhoea/colitis
How and why does it occur?
Firstly, it’s necessary to understand the function of the hindgut, which is made up of the caecum, large colon, small colon and rectum.
It is the most important part of the equine digestive system as it is where fibre is gradually fermented by microbes. This process produces VFA’s, which permeate the lining of the caecum and colon, travelling in the bloodstream and eventually being utilised as an energy source for the horse.
VFA’s are a major contributor to the horse’s daily energy demands, even in racehorses where traditionally we tend to rely more heavily on cereals to provide energy. The microbiome works best when their environment, including the pH, remains fairly constant.
Certain factors associated with racehorse management increase the risk of the hindgut pH becoming too acidic (i.e. hindgut acidosis) these include:
1) Low forage intake. Adequate forage intake is essential to maintain the population of beneficial fibre fermenting bacteria in the hindgut.
These fibre-loving bacteria like a pH of 6.5 to 7.0 and require a steady supply of forage in order to maintain their population. Where forage intake is limited the number of beneficial bacteria decreases as does the pH.
This lowering of the pH favours the growth of lactic acid producing bacteria, whilst also further contributing to a decline and reduced efficacy of the fibre-loving bacteria.
This shift in the hindgut environment can result in irritation and inflammation along the intestinal mucosa, damaging its absorptive capacity, which if left unresolved will lead to a list of issues as discussed.
2) High cereal/starch diets and large individual meals. In theory the small intestine should be able to manage the digestion of starch efficiently via enzymes such as amylase.
However, when the diet contains large amounts of cereals, particularly if these are fed in large meals, inevitable undigested starch makes its way into the hindgut. Here the hind gut microbes easily ferment the starch.
Consequently, production of VFA’s is rapidly increased, as is the production of lactic acid, both of which result in a sharp decrease in pH and a much more acidic environment.
3) Increased stress levels.
A degree of stress is unavoidable in the racehorse’s day-to-day life.
However, where possible minimising stress is important as it can have a major effect of hindgut health. This is not only because stressed horses are less likely to eat, but also because stress can affect the levels of certain hormones (e.g.cortisol) in the body.
These alterations to hormonal balance can directly impact gut motility, gastric and hindgut pH, the health and variety of the microbiome.
How can I tell if my horse has hindgut acidosis?
Identifying the factors that put a horse at risk of developing hindgut acidosis is clear, but confirming whether it is present is not quite so straightforward.
A thorough examination of the horse, including a faecal assessment (pH and bacterial profiles), as well as knowing their history and management will assist you and your vet.
Various new methodologies are being researched, including biosensors.
The hope is that these advancing technologies will enabling early detection of developing problems, thereby allowing any necessary dietary or management changes to be implemented early and quickly before any serious issues occur.
How to limit or prevent hindgut acidosis?
Addressing the management factors which may be predisposing your horse to developing this condition is the best and most appropriate way to limit the damage or prevent the condition altogether.
With modern racehorse management, ensuring a robust microbiome exists through natural foraging and maximum forage intake is incredibly challenging, and almost impossible. Whilst we can provide more forage to the racehorse it is not always readily consumed and the nature of commercially produced forages isn’t always all that diverse anyway.
From a concentrate feed perspective feeding smaller meals (less than 2kg at any onetime) of low starch feeds, will effectively reduce the risk of undigested starch entering the hindgut, resulting in less, if any, disruption to the more favourable fibrolytic bacteria and ultimately avoiding hindgut acidosis.
Likewise choosing feeds that have been formulated to specifically contain ingredients, such as prebiotics and yeast, to support gut health is prudent.
Finally, there are some exceptionally well-formulated and scientifically backed supplements designed to support digestive health (see Box 2).
Sorcha O’Connor MVB, MSc, lead veterinarian in this study, commented: “Nutri-Gard contains 12 key ingredients to support gastrointestinal health including postbiotics, prebiotics, pectin, beta-glucan, key amino acids and B-vitamins.
“I believe the reason we have seen such positive results is because of this unique combination of the ingredients and the way they support the entire digestive system.”
Supplementation proves beneficial
A recent field study by a team of vets and nutritionists examined the effect of feeding a digestive health supplement (Nutri-Gard, manufactured by Foran Equine) to racehorses in full work.
The results showed that when compared to the control group (i.e. those not receiving the supplement) supplementation improved:
• faecal pH, indicating a reduction in hindgut acidosis
• body condition
• faecal consistency
• trainers also noted improvements in temperaments, attitude and energy levels
