Trust Your Gut – the importance of nutrition for health, performance and longevity
/Article by Dr. Richard McCormick, M.V.B., Dip. Eq.Sc., M.R.C.V.S.
The science of equine nutrition is really quite simple – The horse is a flight animal and in the wild, needs to be able to escape from predators using a short burst of energy. Nutrition and subsequent ‘energy’ for survival is all provided by grass which has the required balance of vitamins, minerals, immune supportive nutrients and fiber to maintain a healthy gut microbiota and keep the horse in adequate health for reproduction. Proper functioning of the gastro-intestinal tract (GIT) in horses is dependent on a broad range of micro-organisms and more than half of the energy requirement for their survival comes from the microbial fermentation occurring in their enlarged caecum and colon (Chaucheyras-Durand et al 2022). The bacterial populations resident in the various compartments of the horses intestinal tract vary greatly (Costa et al 2015) and there is more DNA in the bacteria located in the gastro-intestinal tract than there is in the entire body. Because of this, having a healthy gut flora is critical to having a healthy immune system.
In modern times, our demands of horses for performance for our pleasure rather than their survival has led to their need for increased energy that cannot be provided from grass alone. Because of this, the intricacies of diet (in particular the consumption of starch, fiber and fat) has come under scrutiny. Equine feed manufacturers have looked for additional sources of starch, a carbohydrate and a natural component of grass that is ‘essential to provide energy, fiber and a sense of fullness’ (Seitz 2022). Today, most horses and rapidly growing foals are commonly fed diets with >50% of total ration by weight in the form of grain ‘concentrates’ and carbohydrates from oats, maize, soya, barley and wheat. These grain based feeds contain high concentrations of soluble, easily fermentable starches but can be deficient in certain minerals and vitamins so getting an optimally balanced feed ‘right’ is difficult.
Too much of a good thing
With advances in scientific knowledge, we now know that when a horse is exposed to surplus starch, the hydrogen ion concentration of their gut increases promoting the production and absorption of lactic acid, acetate and propionate through the activity of fermentation (Ralston 1994). The process is quick, with lactic acid entering the bloodstream within 3 hours of feeding and calcium subsequently being excreted in the urine. In order to combat this nutrient loss, the horses’ hormone system triggers the release of parathyroid hormone into the bloodstream, activating the release of stored calcium (to maintain optimal blood levels) but unfortunately causing bone demineralisation. Clinically, the horse experiences health consequences of varying degrees including digestive diseases (eg: gastric ulcers, diarrhea, colic or colitis), muscle dysfunction (eg: rhabdomyolysis (known as ‘tying up’), defective bone mineralization (expressed as increased incidence of stress fractures and developmental orthopedic diseases), systemic diseases (such as laminitis, equine metabolic syndrome and obesity (Chaucheyras-Durand et al 2022) as well as potential causes of fatigue.
The ideal equine diet
There is little equine focused research available on the benefits of individual nutrients (due to limited numbers in trials and their subsequent evaluation) of grain ‘concentrates’. But we do know that ingredient availability and quality is regularly influenced by market pressures.
The table (fig 1) below outlines the sugar, starch and fiber components of the various ingredients commonly found in horse feeds. The optimal grain for equine nutrition with its efficient energy source through lower starch content (relative to other grains) and its high level of soluble fiber (relative to other grains) are oats.
The healing power of omegas and short chain fatty acids
While grass provides optimal equine nutrition in its own right, the ‘curing process’ when making hay depletes the valuable omegas 3 and 6 intrinsic in grass. These ‘healing’ nutrients naturally protect the lining of the gastro-intestinal tract by increasing mucous production and alleviating ‘auto digestion’ (via hydrochloric acid). For horses, bacterial fermentation in the hind gut also results in the production of Short Chain Fatty Acids (SCFAs), namely acetic, proprionic and butyric acids. These SCFAs ‘cross talk’ with the gut immune system providing local immunity in the gut as well as protection of the respiratory system, the brain and other tissues against disease. In human medicine, it has been repeatedly established that a dysfunctional gut microbiome is associated with respiratory problems. This is evidenced by the fact that when gut disorders such as Irritable Bowel Syndrome (IBD) or Coeliac disease exist in humans, they are commonly associated with a higher incidence of respiratory infections and related asthmatic like conditions. Barragry (2024) explores the relationship (Fig 2) between gut microbiome and the immune system's ability to support health and combat disease in cattle. A scenario mirrored in the equine.
The stabled horse should be provided with SCFAs daily to support proper functioning gut microbiome. This critical dietary consideration should ideally be provided in the form of flaxseed which has the highest ratio of omegas 3 and 6 (in the ideal ratio 4:1) in the plant world and is most suitable for the equine herbivore.
The health benefits of flaxseed for both humans and equines has been recognized as early as 3,000 BC. Flaxseed was used for various medicinal purposes such as the treatment of gastric disorders, as a soothing balm for inflammation and as a laxative (Judd, 1995). Horsemen (who relied heavily on their equines) and trainers (who sought optimal performance from their charges through natural means) also used flaxseed as a way to supplement the diet with omega-3’s and fiber to produce high quality proteins. Now, thirteen centuries later, we have research to substantiate the knowledge of our ancestors. The renowned German researcher of ‘fats’ and pioneer in human nutrition, Dr. Joanna Budwig, as early as the 1950’s reported that “the absence of highly unsaturated fatty acids causes many vital functions to weaken". Dr. Budwig’s life’s work focused on the dietary ‘imbalance’ between omega-3 and omega-6 fatty acids in humans has been a cornerstone to the exploration of the role of inflammation and the development of many diseases of the coronary, respiratory, metabolic and immune system.
The small seed of the flax plant is also an excellent source of high-quality protein (exceeding that of soybeans and fish oils) and potassium (a mineral that’s important for cell and muscle function). But, the true power of flaxseed lies in three key components:
Omega-3 essential fatty acids – Also known as "good" fats, omegas enhance the oxygen usage of cells and in combination with alpha-linolenic acid (ALA) are anti-inflammatory in their effect within the body.
Lignans – Flaxseed contains 750 - 800 times more lignans than other plant foods (McCann 2007, Yan 2014). Lignans are a group of compounds with antioxidant properties which also contain plant estrogen. Lignans are linked to a reduced risk of developing osteoporosis, heart disease and cancer.
Fiber - Flaxseed contains both the soluble and insoluble types of fiber essential for maintaining ‘gut’ health.
In equines, adding flaxseed to the diet has the immediate benefits of a shiny, healthy coat and fewer skin allergies. Consistent use of flaxseed has multiple long term benefits including strong hoof quality, improved joint health, reduced muscle soreness, faster healing of ulcers (Sonali et al 2008) and significantly impacts inflammation associated with chronic skin conditions (commonly known as ‘sweet itch’). In breeding stock, increased Omega-3 levels in mares’ milk leads to boosted immunity in foals with higher stallion fertility and improved conception rates in broodmares documented (Holmes, 2015).
How diet can influence performance
It is easy to think that ‘providing more is better’ when it comes to using nutrition to support performance. But having excess levels of essential vitamins and minerals being processed by the horses’ sensitive gut has a direct impact on their behavior and willingness to perform. Today, we have greater ‘choice’ at the feed store with a broad range of commercial feeding offerings available including mixes, mashes and supplements but the discerning horse owner can be forgiven for being overwhelmed by the range of diet options for every ailment and stage of life.
In modern times, despite advances in nutrition offerings, we have seen a falloff in performance (Fig 3). During the late 1960s, the U.S. Jockey Club stats noted that racehorses averaged 12 starts per year – a far cry from today's horses racing in the U.S. where the average of 3 ‘starts’ was highlighted by leading US Trainers in 2020 (www.ownerview.com). Unfortunately, this is not just a U.S. based problem, but a phenomenon noted worldwide.
The first equine pelleted feed was formulated in the US by the Cistercian monks in Gethsemani, Kentucky in 1957. Prior to this, all horses were fed ‘straights’ (primarily oats as their energy source and flaxseed as their protein source). My own understanding of the link between modern feeding practices and compromized performance since the 1960s has been curated off an understanding of “what was different” then, as well as a career of observations, clinical practice and scientific review. Fact is, the equine diet of the 1960s was lower in starch and high in fiber. It consisted of oats, minerals, and flaxseed as the “norm”. Hay was the preferred forage (Fig 4).
Today, soya (with one fifth of the omega 3 content of flaxseed) has practically replaced flaxseed as the protein source in equine nutrition. This small change has seen a significant drop in omega-3 and 6 (needed for prostaglandins) in the diet with consequential gastro-intestinal and joint issues. Other dietary changes include those recommended by the National Research Council (NRC) in 1978, who suggested doubling the recommended calcium levels for horses with a subsequent increase in levels of Osteochondrosis (OCD) and Osteopetrosis in the equine population (Krook and Maylin, 1989). Additional moisture in the diet too has led to excess mould formation in convenience feeds and with severe exposure causes liver damage (Buckley et al 2007). Stabled racehorses today mostly lack the nutritional protection afforded a previous generation of horses. The impact has been noted clinically in the widespread increase in equine gastric issues and as stated by J.E. Anthony “Racing fans are missing about half of what they once enjoyed in racing.”
The role of the gut bacteria in the prevention of disease
The gut microbiome begins populating and diversifying from the moment of birth. Though ‘sterile’ in utero, gut derived DNA immediately drives immune health with exposure to nutrition. Recent research suggests that the gut microbiome can be stimulated by using proven probiotics with a track record in enhancing gut health (Barragry 2024). But it is the protective power of SCFAs to allow ‘cross talk’ between the lungs and the gut microbiome that is critical to supporting horses through their life span.
Nutrition using grain ‘concentrates’ is currently at approximately 99% saturation in today’s equine population so a return to feeding ‘straights’ is a swim against the tide of modernity. But, knowing the influence of nutrition on health, performance and longevity it falls on horse owners to be mindful of the consequential impacts such convenience feeds have on the gut microbiome and immune system. Random supplementation and high starch feeds are leading to dietary health issues such as gastric ulcers, hyperinsulinemia and hyperlipaemia (obesity) as well as increased risk of laminitis . So trust your gut and keep it simple – a diet of oats, flaxseed, a multi-vitamin balancer and ad lib hay will not only meet your horses’ energy needs but will keep them happy and healthy too.
REFERENCES
Barragry. TB (2024) WEB https://www.veterinaryirelandjournal.com/focus/254-alternatives-to-antibiotics-probiotics-the-gut-microbiome-and-immunity
Buckley T, Creighton A, Fogarty (2007) U. Analysis of Canadian and Irish forage, oats and commercially available equine concentrate feed for pathogenic fungi and mycotoxins. Ir Vet J. 2007 Apr 1;60(4):231-6. doi: 10.1186/2046-0481-60-4-231. PMID: 21851693; PMCID: PMC3113828.
Budwig, Dr. J (1903-2008) WEB https://www.budwig-stiftung.de/en/dr-johanna-budwig/her-research.html
Chaucheyras-Durand F, Sacy A, Karges K, Apper E (2022). Gastro-Intestinal Microbiota in Equines and Its Role in Health and Disease: The Black Box Opens. Microorganisms. 2022 Dec 19;10(12):2517. doi: 10.3390/microorganisms10122517. PMID: 36557769; PMCID: PMC9783266. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9783266/
Holmes, R (2015) Feeding for stallion fertility. WEB
https://www.theirishfield.ie/feeding-for-stallion-fertility-172113/
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Ralston, S VMD, PhD, ACVN (1994) The effect of diet on acid-base status and mineral excretion in horses in the Journal of Equine Practice. Vol 16 No. 7. Dept of Animal Science, Rutgers University, New Brunswick, NJ 08903
Seitz, A (2022) What to know about starch_Medically reviewed by Seitz, A - MS, RD, LDN, Nutrition — WEB https://www.medicalnewstoday.com/articles/what-is-starch#benefits
Sonali Joshi, Sagar Mandawgade, Vinam Mehta and Sadhana Sathaye (2008) Antiulcer Effect of Mammalian Lignan Precursors from Flaxseed, Pharmaceutical Biology, 46:5, 329-332, DOI: 10.1080/13880200801887732
![[Headline]Scientific research quantifies the impact different pads have on the horse’s performance [Standfirst]The use of pads under the saddle has been common for years, but now scientists are using dynamic testing technology to discover how well they really work [INTRO]In everyday yard situations where multiple horses use the same saddle, putting one or more pads under has been seen as a way of providing cushioning and comfort for the horse, or even relieving pain. However, there has never been any research in racehorses to demonstrate whether this reduces saddle pressures or provides comfort. Furthermore, there is limited scientific evidence to suggest which type of pad is most effective. A recent study suggests that, depending on the material and design, using a pad beneath the saddle might not always achieve the desired pressure-relieving effect. And using multiple ineffective pads under the saddle might not only be a waste of time and money, but it could potentially cause areas of high pressures, compromising the horse’s locomotor apparatus and affecting race performance. [CROSSHEAD] Material matters[FIGURE 1] caption:Peak pressure of more than 35kPa were recorded in two of the three pads. Peak pressure of >35 kPa can cause compression of the capillaries, leading to soft tissue and follicle damage (ischemia) which, in extreme or prolonged cases, results in white hairs, muscle atrophy, skin ulcerations and discomfort. A recent published study evaluated saddle pressure distribution in sports horses using pads made from sheepskin, viscose gel and a medical-grade closed-cell foam. When using a gel pad, the peak and mean pressures increased in the front region of the saddle in trot and canter. This is possibly due to the gel’s lack of ability to dissipate shear forces compared to wool or foam. Similar findings were seen in a pilot study of thoroughbreds galloping at half speed over ground. The same dynamic testing was used (see Technology & Anatomy panel) to compare the forces and peak pressures under polyfill pads, as well as viscose gel and medical-grade closed-cell foam. From the initial trials, the overall forces recorded were significantly higher than those seen in the sports horse study. This seems reasonable, given the difference in locomotion and speed (see Speed & Force panel). Preliminary findings show the forces were 75% lower, and peak pressures were 65% lower under the medical-grade closed-cell foam pad than those recorded under the gel pad. Interestingly the polyfill pad, which deforms to the touch, reduced the forces and peak pressures by 25% and 44% respectively compared to the viscose gel pad. The role of the pad is to act as a dampening layer between the horse and the saddle, reducing pressures and absorbing the dynamic forces which occur during locomotion.Based on findings from the sports horse study, and initial findings from the racehorse study, it appears that the medical-grade closed-cell foam pad is superior in its effectiveness at acting as a pressure-reducing layer between the saddle and the horse. [CROSSHEAD] Pressure to perform Reducing saddle pressures improves gallop locomotion. Horses will still perform when asked, despite areas of high pressures induced by the saddle and pad; but they develop a compensatory locomotor strategy in an attempt to alleviate any discomfort. To increase speed, a galloping horse will either increase stride frequency or increase stride length. Both mechanisms can be used, but the horse will have a natural preference. Published pressure studies have shown that stride length is increased when saddle pressures are reduced. Now, new research is underway quantifying whether a stride frequency approach, which has higher peak forces, could be a compensatory strategy in response to discomfort caused by pressure. Forces are influenced by speed and weight and are produced when the hoof comes in contact with the ground. At racing speeds of 38 mph, the hoof hits the ground approximately 150 times a minute. Stride frequency is an important consideration because a study has suggested that horses have around 100,000 gallop strides before the soft tissues fail. Therefore, any reduction in loading cycles (number of strides) could potentially help reduce injury risk. Harder, faster, longerEvery stride impacts the horse’s joints, causing wear and tear (see Speed & Force panel), so fewer longer strides is the preference for optimum training efficiency. Although horses have a naturally imprinted option, the pressure studies demonstrate that they switch between the two in response to certain extrinsic factors, such as high saddle pressure. Our task as trainers is to optimise the horse’s locomotor efficiency by removing any impediment that might force it to adopt the shorter-stride compensatory gait. We speculate that equipment which increases pressure (such as an unsuitable design of saddle, bridle, girth or saddle pad) will be counterproductive because it may encourage an increase in stride frequency and compromise natural locomotor efficiency. [CROSSHEAD] Contouring is key[FIGURE 2] caption: A saddle pad that is shaped to follow the contours of the back is able to maintain better spinal clearance under the saddle when galloping. In both studies, the saddle pads that were designed to follow the contour of the horse’s back and withers performed better than those that were flat with no shaping. Furthermore, pads with a midline seam connecting the two sides were able to maintain traction and position, providing spinal clearance even at speed. In contrast, pads that were flat without any contouring or with no central webbing seam were observed to slip in response to the horse’s movement, drawing down against the spine under the saddle. This was seen even when the pads were pulled up into the saddle channel before setting off. Quality vs quantityIn an attempt to improve comfort, it’s standard practice to use multiple pads under an exercise saddle. However, adding more shapeless padding can lead to instability and potentially saddle slip. This feeling of instability can encourage the jockey to overtighten the girth in an attempt to keep the saddle still. One study demonstrated a relationship between increased girth tension and a reduced run-to-fatigue time on a treadmill, indicating that girth tension can affect the breathing of the galloping horse. In addition, bulk under the saddle puts a feeling of distance between the horse and rider. This compromises the close contact feel and balance all jockeys strive to achieve and hinders the lowering of the jockey’s centre of mass relative to the horse. Age concernIt’s worth noting that the ability of a material to absorb pressure can be significantly compromised with use and washing, as well as changes in climate. As some materials age, they degrade and lose any initial shock-absorbing qualities. For example, wool loses its ‘crimp’ over time and becomes less effective, so a well-used wool pad may not absorb as much pressure as a new one. The medical-grade closed-cell foam used in the saddle pad studies was developed to prevent capillary damage in bed-ridden hospital patients and the pressure relieving properties are not affected by extremes of weather or machine washing. Saddle systemIt is becoming clear that the saddle, pad and girth operate best when they are viewed as a complete system. When choosing a pad, it’s worth bearing in mind that these pressure studies were carried out under correctly fitted saddles with wide channels and ample spinal clearance. The benefits of a pressure-relieving pad are diminished by a badly fitting or poorly designed saddle with a narrow channel and limited spinal clearance. Likewise, trainers who are experiencing the performance gains associated with advances in saddle design will not reap the full benefits of a pressure-relieving saddle if the fit and effectiveness are compromised by poorly performing pads underneath. [PANEL] Speed & force [FIGURE 3] caption: The hoof exerts a force against the ground, and the ground exerts a force against the hoof, which is transferred through the muscles and tissues of the forelimb. In gallop, the forelimbs have to support two-and-a-half times the horse’s body weight with every motion cycle (stride). In each motion cycle, a fast-moving front foot interacts with the stationary ground and, as the hoof comes to an abrupt halt, the forelimb has to absorb these forces. The forces are transmitted through the soft tissues and muscles to the thoracic vertebrae in the region where the saddle and jockey are positioned. These thoracic vertebrae in front of T16 (the anticlinal vertebra) are responsible for force transmission from the forelimbs, head and neck. The horse’s back does not just have to deal with the large forces from the forelimbs (and hindlimbs) but also the dynamic forces of the jockey, which can be in excess of two-and-a-half times the jockey’s body weight. As speed increases, so do pressures beneath the saddle and pad. There’s a 5% pressure increase when the walk speed rises by 10%, and in trot it goes up to 14%. As the racehorse is travelling at a faster pace the forces involved are inevitably increased and, at gallop with the jockey ‘up in his pedals’, approximately 80% of his weight is focused on the front part of the saddle—the T10-T13 region (see Technology & Anatomy panel). If the saddle pad draws down along the spine during locomotion and creates restrictive pressure, this will interfere with muscle activation and force transmission, potentially causing the horse to adopt the compensatory short-stride gait.The horse will not only need more strides to cover the same distance, but it will also experience more forelimb loading every stride due to the increased speed of each cycle.Studies are ongoing into the long-term impact of this extra limb loading, but we speculate it will potentially result in poor performance and increased risk of injury.[END PANEL] [ PANEL] Stability in Motion[FIGURES 4a,b,c caption: The three axes of rotation]The spine rotates in three directions, providing stability, forcing transmission and generating power efficiently. Lateral bending – left to right Flexion-extension – up and down Axial rotation – rolling one side to the other For optimum locomotor efficiency, the vertebral column needs to be dynamically stable. Stability is the combination of strength and suppleness; it isn’t stiffness. The muscles in the back and neck must be strong so they can support the spine but flexible enough to allow the necessary range of movement and transmission of the dynamic forces required during locomotion.Studies have shown that when the saddle and rider are stable and symmetrical, the horse’s back can stabilise through the cranial thoracic spine at T13 (see Technology & Anatomy), allowing the efficient transfer of forces from the hindlimb.A saddle pad that is causing pressure is likely to compromise this dynamic stability. From a preliminary study, it appears that high pressures are associated with increased spinal instability. This instability is likely to cause the horse to seek a compensatory locomotor strategy and adopt a posture where the back is stiffened. Previous research has shown that back function and gallop kinematics are compromised by a stiffened spine.[END PANEL] [PANEL] Technology & Anatomy[FIGURE 5] caption: Pressure mapping and 3D motion capture are used to quantify the effects of saddle pads on performance at gallop on the track. Thanks to extensive research, scientists now have a greater understanding of the importance of the area around the 10th-13th thoracic vertebrae (T10- T13). This is the location of a high concentration of muscle activity related to posture and movement. Repeated studies have demonstrated how pressure at T10-T13 compromises the locomotor apparatus of the horse and consequently performance. Relieving pressure here affects the mechanics of the whole back, allowing the transfer of propulsive forces from the hindlimb, creating increased power and longer stride length. Testing equipmentResearch teams employ pressure mapping (using a mat with 128 sensor cells on each side of the spine) and 3D gait analysis (using Inertial measuring units) to show precisely how changes in pressure affect spinal movement. The measuring units (IMUs) quantify flexion-extension, axial rotation and lateral bending. The combination of these state-of-the-art measuring systems allows researchers to prove that relieving pressure has a direct effect on spinal kinematics. Long-term trials using pressure testing and gait analysis have demonstrated that back discomfort associated with pressure can affect the development of the horse’s posture, gallop stride and potentially long-term back health. [END BOX OUT] FURTHER READINGR Murray, Journal Equine Vet Science 2019 81 102795 K von Peinen, Vet Journal 2010 538 650-3 S Latif, Equine Vet Journal 2010, 42 630-6 R MacKechnie-Guire, Journal of Equine Veterinary Science 2020ML Peterson, Racing Surfaces white paper, http://www.racingsurfaces.org/bulletins 2012](https://images.squarespace-cdn.com/content/v1/517636f8e4b0cb4f8c8697ba/1619171002004-MBXCIWLV6YDQRJDIHBBU/OPENING+SHOT+%281%29.jpg)
