INDICATORS FOR EQUINE WELL-BEING AND THEIR RELATIONSHIP WITH NUTRITION

Por

COBY BOLGER

Equine Nutritionist and of Founder Horse1, Equine Nutrition Centre

[email protected]

Revista General de Derecho Animal y Estudios Interdisciplinares de Bienestar Animal / Journal of Animal Law & Interdisciplinary Animal Welfare Studies 3 (2019)

ABSTRACT: Humanity has enjoyed existence-altering advantages from the horse/human relationship, and horses have also benefited as a species. In the current political climate, horse welfare and ethical treatment is fast becoming a flashpoint. European animal welfare mandates are applicable to equids, but their practical implementation is difficult, as that of other laws and guidelines, since it is currently subjective, largely undefined and varies between countries and between type of horse. Different national associations and entities related with the equines have varying requirements and the fact that the horse is both considered a pet, an athlete and consumed as food makes defining equine welfare a challenge. The aim of this article is to explore how the extensive base of existing scientifically proven research, as related to equine nutrition, can simplify the creation of a series of objective well-being indicators or guidelines that will serve equine enthusiasts, commercial horse meat producers and legislators. The equine digestive tract is so sensitive that if the horse is provided with indigestible feedstuffs or the ration is managed incorrectly, the animal in question will quickly suffer from depression, reduced performance, illness or death. An initial outline of horse welfare checkpoints related to equine nutrition could include: 1) Evaluating corporal fat deposition on the horse; 2) Ensuring sufficient daily fiber and water intake; 3) Ensuring that the feedstuffs provided are appropriate for the equid digestive tract; 4) Ensuring the correct timing of feeding; 5) Monitoring variations in daily ingesta of feedstuffs and/or water; 6) Monitoring the use of cereals in the diet; 7) Evaluating strategies related to the ration; 8) Evaluating the hygiene and correct storage of the feedstuffs; 9) Evaluating the social groups, size of living spaces and the interactions between individuals when feeding; and 10) Evaluating how and where the feeds stuffs are provided both on an individual level and within social groups.

KEY WORDS: equine nutrition, horse welfare, digestive tract, health.

CONTENTS: I. INTRODUCTION. II. The History of Humanity and the Horse. III. Modern thoughts about human responsibility to the animals on our planet. IV. The Difficulty OF Interpreting the “FIVE Freedoms.” V. A way forward. VI. What is well-being? VII. CURRENT LEGISLATION RELATED TO NUTRITION AND EQUINE WELFARE. VIII. Why nutrition and the digestive tract ARE important to equine welfare. IX. Modern equine nutrition. X. Typical illnesses and problems related to the incorrect management of the equine digestive tract. XI. Vices, stereotypies and horse welfare. XII. How to develop a dashboard of equine welfare indicators? XIII. Condition scoring and horse welfare. XIV. How much does a horse eat? XV. How can we determine a horse’s weight? XVI. Basic functions of the horse’s digestive tract and the relationship to equine welfare. 1. The equine mouth and esophagus. 2. The equine stomach. 3. The small intestine. 4. The equine hindgut or large intestine. 5. Other details about the equine digestive tract. 5.1. Hydration of the horse. 5.2. The relationship between the well-being of the gut and physical activity. 5.3. Social contact and digestive pathologies. XVII. What Is the difference between a competition horse’s diet, a pleasure horse’s diet and a feral horse’s diet? XVIII. In SUMMARY. BIBLIOGRAPHY.

INDICADORES DE BIENESTAR EQUINO RELACIONADOS CON LA NUTRICIÓN

RESUMEN: La humanidad se ha beneficiado de las ventajas que ha supuesto la relación caballo/ser humano para su existencia, al igual que lo han hecho los caballos, como especie. En el clima político actual, el bienestar y el tratamiento ético de los caballos se están convirtiendo en una cuestión crítica. Los mandatos de bienestar animal de los países de la Unión Europea se aplican a los équidos, pero su implementación práctica es difícil, dado que, al igual que la de otras normas y directrices, es actualmente bastante subjetiva e indefinida, y varía entre países e incluso según el tipo de caballo. Las diferentes asociaciones y entidades nacionales relacionadas con los équidos exigen distintos requisitos y el hecho de que el caballo sea considerado tanto animal de compañía, como atleta, o que se consuma como alimento, hace que definir el bienestar equino sea un desafío singular. El objetivo de este artículo es explorar cómo los resultados de la investigación de sólida base científica, relacionados con la nutrición equina, pueden simplificar la creación de una serie de indicadores o pautas de bienestar objetivos, que sirvan tanto a los amantes del caballo como a los productores comerciales de carne y a los legisladores. El tracto digestivo equino es tan sensible que si se le suministra comida no digerible o si se manejan de manera incorrecta las raciones, el animal de que se trate sufrirá rápidamente depresión, disminuirá su rendimiento, o tendrá enfermedades, llegando incluso a morir. Un resumen inicial de los puntos de control del bienestar equino relacionados con la nutrición podría incluir: 1) evaluar la acumulación de grasa en el caballo; 2) asegurar la suficiente ingesta diaria de fibra y agua; 3) asegurar que la alimentación es adecuada a las necesidades de su aparato digestivo; 4) asegurar la disponibilidad temporal correcta del alimento; 5) monitorear las variaciones del alimento y del agua ingerido diariamente; 6) monitorear los cereales incluidos en la dieta; 7) evaluar las estrategias a utilizar para calcular las raciones adecuadas; 8) evaluar la higiene y el correcto almacenamiento del alimento; 9) evaluar los grupos sociales que se forman para alimentarse, el tamaño de sus espacios vitales y las interacciones entre los distintos caballos cuando se están alimentando; y 10) evaluar cómo y cuándo se suministra el alimento a cada individuo y como arte de un grupo.

PALABRAS CLAVE: nutrición equina, bienestar equino, tracto digestivo, salud.

I. INTRODUCTION

Evolution of human civilization leads us to reflect on our responsibility to the planet and the living creatures around us. Specifically, the close relationship between human beings and the horse is being closely evaluated. There is a myriad of opinions about what horses need and want.

Current legislation is often controlled by different entities, from local and national governments, as well as international organizations. Also, private entities, like the International Equestrian Federation or the Jockey Club, national federations for Sport, the Olympic Committee, breeding federations, etc. have rules that apply to their affiliates or non-mandatory guidelines that are used by decision-makers as standards of conduct. The list is never-ending.

Each of these entities has a separate set of rules, regulations, licenses, equine identification papers, passports, microchip requirements, movement requirements and permissions, sanitary and hygiene information, parasite control, vaccines, health controls and competition history. Of course, there is a monetary cost related to every detail.

None of the entities have the same goals or definition of equine welfare. Horses, in some circles, are considered pets, even a part of the family that should never be ridden. They are also used as athletic partners, as livestock for other multiple uses, or are eaten for dinner on Sunday! This is an enormous challenge for legislation.

In spite of the huge infrastructure and business related to the equine industry, formal education is not easily available. Low pay scales and the physical danger related to the equine sector as well as the practice of apprenticeships to train professional riders, reduce the incentive to create university level degrees. Like singers and actresses, many aspire to ride professionally but few make the grade to win the big prize money or sell expensive animals. Although many books and articles are written on the subject of equine welfare, the horse industry is plagued by “experts” who can set up shop as advisors or consultants with literally no training or experience.

Perception, outside the horse industry, of how equines interrelate with humanity, consistently underestimates the economic strength and growing opportunity within the sector. Few resources are channeled into the sector to develop much-needed professionals.

Public opinion is ever more demanding of ethical treatment of all animals, including horses. Given the interest in welfare of this complex combination of interest groups (horse enthusiasts, equine sport organizations and equine meat producers) legislators and regulators are facing an increasingly difficult political climate that demands intelligent decision-making.

The objective of this article is to explore information related to equine nutrition and nutrition management that demonstrates how scientific study could be utilized to objectively define equine welfare indicators based on well-being and specific wellness. This contrasted information and process could form part of a coherent equine welfare “dashboard” for use by equine enthusiasts, equine meat producers or legislators and regulators as needed.

II. THE HISTORY OF HUMANITY AND THE HORSE

The history of the relationship between the horse and human beings is documented from around 5,500 years ago in Kazakhstan (Gaunitz et al. 2018). Archaeologists determined – and geneticists have confirmed – that the Botai tribe were the earliest known humans to tame and breed the horse (De Barros Damgaard et al. 2018). To put this in context, horses were interacting with humans, providing meat, milk and transport before the existence of organized government (Maisels 1993).

Human admiration and the history of collaboration between human and horse is well documented and even idolized through mythology, legend, folklore, literature, poetry and artwork. There are drawings of horses in the Altamira and Lascaux caves, paintings in Egyptian tombs, stories of Arab mares living in the tents of the Bedouins. People feel an indescribable loyalty and kinship to their animals and especially their horses. In France, the stables at the castle of Chantilly were enhanced by Louis Henri, Duc de Bourbon, because he believed he would be reincarnated as a horse.

As our ancestors are important to us, we also give great importance to horse ancestry. Bedouins tracked the ancestry of their horses through an oral tradition. “Asils,” the purest of the Arab horses, were strictly controlled and it was forbidden to breed these valuable mares with non-Asil horses. Written pedigrees for Arab horses are first recorded in 1330 AD (B.S. Lewis 2006). Today’s thoroughbred horses can easily be traced back 300 years to three foundation sires (Milner 1990). As Emerson once said, “each creature is only a modification of the other; the likeness in them is more than the difference, and their radical law is one and the same” (2009 [1836], 8). Horses were and continue to be considered powerful and magical, a source of beauty and a workmate to man.

Before World War II, the well-being of the horse was the key to the well-being of its humans. The reliance of humans on their horses was literally life and death. Without horses, humans would not have farmed, hunted, travelled or engaged in war in the same way. According to the Food and Agriculture Organization (FAO), while feral populations of horses do exist, there are many more domestic horses. Where other animal populations have faltered, the close relationship with humans has allowed the domestic horse population to remain strong.

People within the equine industry refer to themselves as “horsemen,” “horsewomen,” or the gender approved “horseperson.” Riders have to “earn their spurs.” Good riders describe “holding the reins as if they were silk threads.” Families with horses (my own included) require the children to take care of the horses before anything else is done. Sportsmanship and kindness to horses is given priority over winning ribbons. Horses always eat before the family. This is not considered odd or unreasonable.

It is common for people outside the horse world to underestimate this intimate link between horses and humanity.

III. MODERN THOUGHTS ABOUT HUMAN RESPONSIBILITY TO THE ANIMALS ON OUR PLANET

Thinkers, educators and the general public are pondering the relationship between the horse and human. Is this relationship with the domestic horse based on symbiosis, slavery or collaboration? There is introspection as to what responsibility humans have to guarantee the well-being and even happiness of the horse now, and in the future.

There is movement toward legislating this responsibility both for the horse and for all animals: domestic, feral and wild. Countries like France, the Netherlands and Denmark have taken the lead in enacting formal legislation requiring a highly defined infrastructure for prospective horse owners and equine installations.

The United Kingdom and the European Union, continuing with this trend, set forth the following rules, known as the “Five Freedoms” regarding farm animals, which include horses (FAWC 2009):

Freedom from hunger and thirst

Freedom from discomfort

Freedom from pain, injury and disease

Freedom from fear and distress

Freedom to express normal behavior

This interest in horse welfare is echoed by article 13 of the Treaty of Amsterdam 1999 on the Functioning of the European Union, which states that: “ . . . the Union and the Member States shall, since animals are sentient beings, pay full regard to the welfare requirements of animals, while respecting the legislative or administrative provisions and customs of the Member States . . .” Article 13 is clearly the early stage of a major change in our perception of the animals in our lives. Is it ethical to ride a horse? Can we contemplate the idea of eating a sentient being? Is a horse a farm animal? Is it a pet? Is it an athlete? Or should it be treated as a wild thing and observed from afar?

Animal rights activists are pushing forward, advocating that animals should not be considered property or economic assets. For the moment, habeas corpus, a legal recourse for avoiding illegal confinement for animals, has been turned down in several legal cases in Europe and the United States, but there are cases still under appeal (Economist, 2018). The mere idea of these cases was unthinkable twenty years ago.

If scientific research continues to confirm the existence of animal cognition, we will eventually be forced to reassess our relationships with all animals, including our horses.

IV. THE DIFFICULTY OF INTERPRETING THE “FIVE FREEDOMS”

In my opinion, to properly interpret the initial “Five Freedoms” for the horse, which are the minimum that should be taken into account regarding equine welfare, humans have a responsibility to incorporate science-based and peer-reviewed best practices that properly evaluate the horse’s physical and psychological needs. Following this logic, the next practical step is to study or use existing research on horses’ feral and domestic ethology and physiology to come to findings that can be shared, taught and, if necessary, legislated.

There are conflicting opinions about the correct way forward. As is so typical, different interest groups consisting of horse owners, the general public or farmers producing horses for meat have adopted extreme and, in some cases, dogmatic views. Animal welfare is set to turn into a political battleground in the coming decades.

To further complicate this debate, it must be noted that human relationships with animals have become distorted in modern times. It is estimated that between six and eight million horses were killed in World War I (Johnson 2006, Dassanayake 2015, IMH 2019, War Archives 2012). And notwithstanding motorization in the interwar period, the number of horses used in World War II was still quite substantial, in particular those used by the German and Soviet army (Street 2017, Johnson 2006, Dunn 2005).Growing urbanization and the more widespread use of the car and tractor after the wars, further increased the separation between humans and horses, both conceptually and spatially.

Human day-to-day existence has ceased to depend directly on the well-being of our equines. A sick horse no longer means an unplowed field or not being able to travel to town or to the doctor. Today, horses are our pets, animals used for therapy, a partner in sports or maybe a meal.

The great divide between man and animal is reflected clearly in the anthropomorphism and romanticism directed toward the horse. We have gone from sharing our tents, caves and sustenance with our horses to tucking them up with blankets at night in a closed stable or admiring them in fields from afar, never asking them to work, believing that to be mistreatment. Horses, in many circumstances, have become mollycoddled pets, living in small box stalls, alone, with mere minutes of access to the outdoors, sometimes being closed in days on end. Other horses are kept outside, in small, unprotected paddocks or barren fields, their hooves soft from standing in muck. Living, according to their owners, “a natural life.” Both types of horse owners, if asked, will insist that their horses are perfectly cared for and happy.

Mini-courses of equine study that promise professional level experience in a few hours or a weekend cause us to underestimate the complexity of acquiring in-depth knowledge. Our impatient “Twitter generation” is unused to dedicating time to slowly acquired understanding of intricate and inter-related subjects like equine care and behavior.

The extreme opposite situation exists with horses destined for slaughter. Minimal legislation has been developed to control these horses’ diets for health purposes, as these horses may be introduced into the human food chain. Some measures have been legislated to reduce their stress in transport and limit undue cruelty during slaughter (Animal Transport Guides 2017). However, equine welfare is clearly put into question by horrific published articles claiming that horse slaughter is controlled by organized crime or that sick or lame horses are transported illegally to slaughterhouses and end up in the human food chain (Duffin 2013).

These topics are easily politicized and the emotional images of mistreatment can create an environment of “knee jerk” reactions. To further complicate this issue, horse owning and riding is often perceived by the public as elitist and cruel by a non-horse populace (Abadi 2018; Emerson 2016; G.G. 2012). It is easier for officials to close stables, reduce access to horse activities or even ban the endeavors altogether to avoid negative press (Bissinger 2012).

V. A WAY FORWARD

If the objective of developing horse welfare guidelines is to aid horse lovers, owners, horse meat producers and possibly future legislators, to improve the health and well-being of these animals, one can take a more pragmatic approach to avoid current and future political landmines.

Recommendations can be based on a research related to horse ethology and physiology, ration management and the physical requirements of the equine digestive tract. It is important to be able to defend any recommendations with a body of serious research and we must be able to adjust these recommendations in an agile manner when further investigation is produced and receive general consensus. The horse’s popularity among the public and the monetary value of the breeding and sport horse has justified a large base of expensive scientific and peer-reviewed investigations. This body of research can be used as a foundation for decision-making.

Several countries with large horse populations have formed investigative laboratories or groups to study the horse and create a depository of knowledge. The United States, through the National Academy of Sciences National Research Council (NRC), established in 1863, has published several versions of nutritional requirements for horses and equids. The latest version was published in 2007 (NRC 2007). France, Germany, England and the Netherlands also have similar national publications: The French National Institute for Agricultural Research (INRA), the German Society for Nutritional Physiology "Gesellschaft für Ernährungsphysiologie" (GfE), the Animal Research Council (ARC) in Great Britain or the Dutch Centraal Veevoederbureau (CVB).

Investigators in Holland have developed initial quality evaluations for equine housing and pasture management (Van Dierendonck 2017) that are adopted voluntarily in some stables, although they have not yet been integrated within legislation or official education. Size of stables and paddocks, how the diet is managed and how the horses are divided socially is taken into account. There are many scientists working worldwide toward understanding the horse.

Professional associations, universities, private equine investigation centers and periodically organized conferences exist that are dedicated to furthering equine investigation. These associations are focused on keeping scientists, vets, industry professionals and the interested horse owner updated on current research and discussions. Examples of some well-known associations and investigative laboratories dedicated to science and equine welfare are: World Organization for Animal Health (OIE), Middleburg Agricultural Research Centre from Virginia Tech (MARE Center), Kentucky Equine Research (KER), Equine Studies Group at Waltham Centre for Animal Studies, The Animal Health Trust (AHT), European Workshop on Equine Nutrition (EWEN), The British Society of Animal Science (BSAS), European Society of Clinical Veterinary Ethology (ESVCE), the American Association of Equine Practitioners (AAEP) or the International Society for Applied Ethology (ISAE), among others.

In Europe, Australia, New Zealand and the United States, there is a formal requirement to broaden skills and maintain professional competence known as Continuing Professional Development. This requires professionals such as veterinarians, equine nurses and nutritionists to dedicate a certain amount of time to formal lifelong learning after graduating. For example, veterinarians in the UK are required to receive an average of 35 hours per year and 105 hours over any 3-year period of time (RCVS). Professionals have the responsibility of keeping a Professional Development Record and keeping track of continuing education, the type and total hours along with the official certificates from the courses and activities. These scientific meetings, workshops, presential and online courses are legalized as official continuing studies that can be applied to this requirement. At the writing of this article, the CPD requirement is not applied in Spain.

Horse owners trust veterinarians and rely on them for nutritional and management advice (J. Murray et al. 2018). As veterinarians often work directly with the public, and at every level of the equine industry as well as within government, training this group of professionals may be the key to getting current and newly introduced welfare information applied on a practical level.

VI. WHAT IS WELL-BEING?

The definition of well-being, taking, as example, how the Merriam-Webster defines it since 1561 (“the state of being happy, healthy, or prosperous”), implies a complex and subjective exercise when applied to a horse. Other paths to assess welfare might use more concrete values like lifespan and the definition of the quality of life. However, a formal strategy for checking horse welfare, in particular when related to health, can be relatively simple.

Many of the indicators directly associated with both welfare and well-being are related to the horse’s diet and diet management. The horse’s digestive tract is so sensitive that even relatively slight mismanagement can cause serious physical and psychological problems that can result in the horse’s illness or death. So, the obvious first priority to guarantee horse welfare is to not kill the horse by mistake. We can then proceed to measures of less priority although not of lesser importance related to well-being. These requirements can be applied to all equids.

If we take well-being one step further to attempt, beyond health, to include happiness or satisfaction, we once again enter into the realm of nutrition and management. How the feedstuff is given throughout the day is as important as what feedstuff is included in the ration. The easiest way to begin is to try to mirror the activity of feral horses, which has been well studied (Van Dierendonck and Wallis 1996; Van Dierendonck et al. 1996). Horses need to keep busy foraging for at least 13 hours a day in numerous feeding bouts (Ellis 2010). Fasting is not natural behavior for horses (Ellis 2010). During a 24-hour period a horse will have feeding bouts throughout the day and night (Ellis 2010; Mayes and Duncan 1988). Insisting on human feeding habits and mealtimes is probably one of the main causes of equine mistreatment related to nutrition.

Another significant detail, to avoid absurd situations that arise through incorrect interpretation of different guidelines, is to differentiate how and where these rules should be applied. An acceptable level of care, which may be appropriate for the horse destined for slaughter, is certainly not an optimal level of care, and this must be clearly understood. There is a huge abyss between minimum requirements for well-being that should be legislated, a sort of minimum “well baby check” that a trained layman can perform, and the state of true well-being of a horse, which requires a polished and thoughtful day to day strategy.

VII. CURRENT LEGISLATION RELATED TO NUTRITION AND EQUINE WELFARE

Animal welfare in general and welfare specifically related to equids in Europe is documented as beginning in the mid-1800’s with the establishment of the Society for the Prevention of Cruelty to Animals (SPCA) in 1824 and the publication of the novel Black Beauty by Anna Sewell in 1877. In France the Grammont Law was passed in 1850 (Pierre 2007).

European Union (hereinafter EU) legislation does not regulate the nutrition of horses as it relates to welfare beyond the very general statements of Council Directive 98/58/EC of 20 July 1998 concerning the protection of animals kept for farming purposes, and Regulation (EU) 2018/848 of the European Parliament and of the Council of 30 May 2018 on organic production and labelling of organic products which most likely refers to equid meat production. The general references in article 3 of the said Council Directive 98/58/EC declare that the law of the member States should have due regard for their “physiological and ethological needs in accordance with established experience and scientific knowledge,” remanding explicitly to provisions set out in the Annex whose point 14 states that “no animal shall be provided with food or liquid in a manner, nor shall such food or liquid contain any substance, which may cause unnecessary suffering or injury.” Regulation 2018/848 states in its introductory reasoning nº44 that “organic livestock housing conditions and husbandry practices should satisfy the behavioral needs of the animals and should ensure a high level of animal welfare,” further establishing some nutrition requirements for ecological production of equines in point 1.9.1.1 of Part II of its Annex II. While these statements are correct, it would be impossible to use them to actually formulate or check a ration of any equid or know if its welfare needs were being met.

This problem is also reflected in the words used in the new “Animal Health Law” of the EU,(1) which codifies most of the current multiple legislation on the field and which will enter into force on April 21, 2021. The wording of some of its the statements, such as that “all animals must have access to feed at intervals appropriate to their physiological needs” or “no animal shall be provided with food or liquid in a manner, nor shall such food or liquid contain any substance, which may cause unnecessary suffering or injury,” while sounding welfare-conscious and may be of some use in prosecuting cases of abuse, does not supply enough particulars to be of any real help in practical matters.

As a nutritionist, I believe that the complexity of writing legislation yokes most authors into using ambiguous terms that must later be interpreted. As the majority of legislators are unfamiliar with the importance of fiber in the equid diet, and how fiber and different forages are defined and measured in terms of equid ingesta, there is the fear that some, currently unknown, new and modern feedstuff will come along in the future and change everything; this is why the recommendations are so vague as to be useless.

The discussion over what horses should and should not eat is not new. An equine ration book published in 1908 lists some typical ingredients used at the time including kilthi, gram, moth, urad and mung (Indian beans/peas) (Harris 1998 2698S). Another equine nutrition book, written for the military in Great Britain and published in 1927, lists hay, straw, oats, maize, beans or dried grains as the staple diet of horses. Yet another publication mentions that meat, cut up into small pieces and rolled in bran was fed successfully during the battle of Metz. Still today, Icelandic ponies may still be fed herring in the winter. None of these texts mention any comparison in the number of digestive problems or change in lifespan related to these feeding regimes. The equids were fed then and continue to be fed now what was available locally and what did not quickly kill them.

And that common catchphrase, “in accordance with scientific knowledge” (as seen in the above cited Council Directive 98/58/EC of 20 July 1998), as well as the one included in Article 6 of the European Convention for the Protection of Animals kept for Farming Purposes of 10 March 1976 (as amended by a subsequent Protocol of 1992), which declares that only substances that are “demonstrated by scientific studies of animal welfare . . . [to be] not detrimental to the health or welfare of the animal” are a convenient way for officials to sidestep legislative responsibility to recognize traditional and long-used feeding solutions. If we ignore the negative aspects and limits in scientific testing protocols, in many cases the legislation only serves to burden commercial hay and feed producers, often family owned small businesses, with undue or disproportionate costs related to testing requirements on feedstuffs that has been naturally produced using the same procedure for thousands of years.

The machines have changed, but hay is still produced the same way.

Photo by Coby Bolger, EWEN Meeting (Sweden 2018).

Scientific testing is all well and good; however, it is limited and it is costly. This may sound hard-hearted, but one must question how much testing and research is reasonable on traditionally produced feedstuffs for a relatively small number of animals dedicated to sport or pleasure.

In the end, feeds and commercial products appear on the market that do end up being unsafe for the domestic horse. They usually disappear if the animals exhibit health problems or poor performance, or they disappear because they are expensive or difficult to produce or because there is no notable difference in performance of the horse.

The majority of legislation related to equine nutrition is set forth in order to protect humans if or when an equid enters the human food chain (see Regulation (EC) No 767/2009 of the European Parliament and of the Council of 13 July 2009 on the placing on the market and use of feed). Currently there is no differentiation in feeding requirements between equids destined for sport and those produced for slaughter. In the rest of Europe, horse owners can declare on the horse’s domestic sport horse passport that the horse is “not intended for human consumption” (VMD-DEFRA). This declaration is irrevocable. In Spain, this option is not available upon the writing of this paper and although the equid will never enter the human food chain, there is no change on the legislation related to nutrition.

This creates an undue cost and administrative burden for businesses catering to feeding the sport horse. For example, Spanish feed suppliers by law must track each and every bag of feed to the consumer or distributor by batch and bag number, a costly task that is more stringent than requirements placed on supermarkets. This obviously has nothing to do with equid welfare, as the majority of equids who eat expensive commercial feeds are used for pleasure or sports.

The above cited new EU “Animal Health Law,” which will enter into force on April 21, 2021, nevertheless continues to separate the concepts of equine welfare, food hygiene and public health.

In the end, the responsibility of enforcing these mandates falls on the shoulders of some local officials, who have to interpret the guidelines using whatever knowledge they may have. Some may be openhanded and leave the local horse owners to their own devices, relying on condition scoring, evaluation of installations and consumer complaint to monitor welfare. Others, however, may force local supplement shops, hay and feed business or riding schools into bankruptcy by compelling them to justify each and every nutrition related decision (how the feedstuffs are stored, the wording on the feed labels, etc.) and subjecting them to constant inspections and tracking of batches.

It is not difficult to set forth general strategies for basic nutrition to ensure equine welfare. It is fiendishly difficult to set forth specific nutrition related mandates for horses in work. Once horses reach an exercise level that requires them to receive higher caloric intakes provided by commercial feedstuffs, the business of feeding horses inevitably takes over.

Horses compete for raw materials with other farm animals. The costs of raw material such as oats, barley and soy, typically used in equine feeds, as well as costs related to vitamin and mineral premixes, bag cost and transport to the farm will mark the cost of producing the product and end user price. As is expected with commercial interactions, the manufacturer or distributor will try to improve sales margins, sometimes ethically by reducing transport costs or changing bag types or service strategies, or sometimes less ethically, by varying the raw materials, protein sources or vitamin and mineral correctors according to price fluctuations, even if this may result in lower quality or indigestibility of feedstuffs (for the general issues concerning the costs of protein, availability and supply, see Chadd et al. 2002).

Legislation is also difficult because of the varying levels of quality among different raw materials and the many types of manipulation of these feedstuffs offered by feed mills (Ralston 2008) that have an effect on digestibility. There are types of nutrients that do not absorb well in the equid; however, this may be improved or diminished by the manipulation of raw materials using heat or water. Digestibility is also affected by the proportion and total amounts of the combination of raw materials (Geor 2002; Ralston 2008). For example, an excess of calcium (which is relatively inexpensive) in a feed may reduce the absorption of more expensive microminerals such as copper or zinc (Huntington 2011).

However, strict legislation may not be necessary in this instance. As was stated at the beginning of this paper, incorrect nutrition will quickly reflect in the horse’s performance and with the horse in work, the objective is the ability to work. The key to equine welfare related to feed management and quality on this level may be educating the horse owner to identify digestible raw materials within commercial products and to understand the basis of scientific studies that will prove the efficacy of the feed or supplement. The owner will notice if the horse is not doing well on a feeding regime and change the ration. And as is the way of horse people the world over, word of mouth will do the rest (KER 2012).

Concerning the international standards set forth by the OIE Terrestrial Animal Health Code for the improvement of animal health and welfare and veterinary public health worldwide, within its 27th edition (which incorporates modifications agreed on at the 86th OIE General Session, May 2018), there is a text included in Chapter 7.12 on “Welfare of Working Equids” which focuses on feeding, behavior and management.(2) The Code defines the 8th measurable criteria (fitness to work) as the “the state or condition of being physically sound and healthy, especially as a result of exercise and proper nutrition, to perform work well.” This document also fittingly mentions that in many populations the working equids are fed incorrectly because of lack of knowledge or resources. These statements are all correct; however, there may be a perception from local citizens that this type of directive is paternalistic and insensitive to local economic conditions.

How efficient are global directives on equid welfare in situations of dire poverty?

These Guatemalan children make a living taking tourists to go up the mountain to see the live volcano on horseback. Tourists are not recommended to visit this area because of the high risk of crime (OSAC 2018).

More detailed and in-depth well-being criteria can certainly be devised for some situations. Regarding domestic equids, in areas with clearly sufficient resources, a quality evaluation system for installations can be defined for use by riders, owners, legal officials, etc. A system akin to the stars applied to restaurants or hotels that can be easily interpreted by everyone can be implanted. It would be relatively simple to put the process in motion and educate the public with an organized strategy.

However, in countries where there are few resources, precarious finances and little education, the solution to equid welfare is not so simple. Gaining awareness and buy-in related to equid welfare within these communities will have to be addressed differently, possibly in parallel with improving the circumstances of the human population. In the end, education may be more effective than legislation.

VIII. WHY NUTRITION AND THE DIGESTIVE TRACT ARE IMPORTANT TO EQUINE WELFARE

The well-being of the horse is inextricably entwined with what and how it eats. Although horses have been intimately involved with human activities for thousands of years, the equine digestive tract still requires similar types of fiber-based nutrient sources as their ancestors millions of years ago.

During the numerous cycles of Pleistocene and Holocene glaciations, some of them covering almost three quarters of the land mass in Europe, many species, including humans and horses, survived by moving to “refuge areas” in the Balkans, Iberia and Italy (Arroyo et al. 2004, 32). It was still cold, but they were able to incorporate strategies to survive. Humans sought refuge in caves or simple dwellings and, as is shown by the enzymes present in our own digestive tracts today, were able to eat a wide range of food with more or less success. Our ancestors ate everything from plants to fish and crustaceans, or mammals, snakes and insects. We adopted a philosophy of nutritional trial and error, often detrimental to our health and lifespans, but humans were able to survive and reproduce.

The horse survived by adopting a different strategy. Horses were able to paw through snow and ice to eat the forage underneath. The horse’s digestive tract is still only adapted to a limited range of foodstuffs. You will not find a horse happily digging in to a steak. It just does not have the digestive enzymes or intestinal flora needed to absorb it.

Although historically there is limited information published solely on horse nutrition, there are many mentions in antique military and veterinary tomes referencing equine diets and how those diets were managed (Ejercicio de la Guerra y el Arte Militar 1735; Pinto Pacheco Pello 1670). The first reference we have about horse feed is dated to Roman times and related to war horse nutrition. A type of barley “cookie” for the horse was provided to increase its energy level and capacity for physical performance (Hyland 1990, 41).

Library Real Maestranza de Cabellería de Ronda, Spain.

Photo by Coby Bolger.

Interestingly, the same concepts and challenges we have today with domestic horses are mentioned in these ancient texts. There are diets to increase horses’ weight, muscle mass and energy. There are diets meant to calm nervous horses and prevent illness, such as colic, skin problems or laminitis. There are numerous references to the capacity or incapacity of horses to digest different feedstuffs, evaluating horse health and physical ability. The medical interpretation is often incorrect, and there is talk of the four “humours” and other ideas that have been long since been proven wrong. But our ancestors’ observations on horse health showed great perspicacity.

Many of the solutions used then are exactly the same strategies that have been scientifically proven as effective today. Solutions like increasing digestibility by cooking barley or corn, increasing the fiber in the diet or adding oil and salt were concepts used both then and now (Luthersson and Nadeau 2013, 561; Vervuert et al. 2007; Julliand et al. 2006; McLean et al. 2000; Granfeldt et al. 1994).

Horse feces and urine recollection diaper for equine nutrition digestibility studies.

Photo used with the permission of Kentucky Equine Research Investigations.

IX. MODERN EQUINE NUTRITION

Today, interested horse owners or equine managers can easily inform themselves through books, courses and research. With the information in hand, correct equine nutrition can be formulated at home by the owner or is easily available commercially.

However, many riders and managers base their horse’s nutrition on their own philosophies regarding nutrition, as well as on rumors and marketing messages that are rife within social media. Careful observation of horse health and performance is not always used. Different feedstuffs are routinely demonized and then just as mysteriously brought back into favor. Equine nutritionists field requests for “organic non-gm feed,” “no sugar feed,” “no oats feed,” “no molasses feed,” “natural herbal feed,” and a never-ending list of other requirements from owners who have little to no understanding of the nutritional concepts they are asking for.

Industrialization of animal feeds and the use of by-products originally used for human consumption have taken the priority away from the value of nutrition and the direct connection with the horse. Some feed manufacturers, in their relentless desire for profit, or possibly in ignorance or lack of respect for the horse, offer horse owners feeds formulated for other species, or even allow horse owners without any nutrition training to formulate their own feeds. These facilities often lack feedstuffs or mineral correctors specific to horses and produce bovine or porcine feeds on the same manufacturing lines, without appropriate hygiene protocols. Cross contamination or incorrect formulation can cause serious, life-threatening pathologies (FDA 2018). Horses have very precise nutrition requirements. Specific digestibility of the feedstuffs and correct nutrient balancing is crucial to equine health and requires extensive training.

Almost laughably, many of these owners will believe that their horses are eating a “natural or traditional diet,” without any idea about what either of those concepts means for a horse. While riding has been homogenized and is easily contrasted in competition on a worldwide level, much of the historical information on training and nutrition has been lost or is misunderstood. Modern scientific studies are often twisted to buttonhole simplified marketing messages.

Ideas on horse and ration management have been introduced that are clearly not in the best interest of the horse. The historic loss of our constant daily contact with the horse has caused eighty years of a “dark age” in equine nutrition.

X. TYPICAL ILLNESSES AND PROBLEMS RELATED TO THE INCORRECT MANAGEMENT OF THE EQUINE DIGESTIVE TRACT

Incorrect ration management, indigestible feedstuffs or sudden changes of diet can increase the risk of certain pathologies related to the digestive system. Specifically, colic, a general term that refers to an equine stomach-ache, has been identified by the US Department of Agriculture (USDA) National Animal Health Monitoring System as the second leading cause of death in horses (USDA 2001). Statistically, in a study published in 2000, with over 1,026 horse operations, incidence of colic was 4.2 events/100 horses. Of those colic incidences, 1.4% resulted in surgical intervention and the fatality rate for all colic events was 11% (USDA 2001).

Laminitis, an inflammation of the laminae in the feet caused by a metabolic crisis due to a debilitated digestive microbiota, among other reasons, is also a common ailment (Pollitt and Visser 2010). This extremely painful pathology can leave the horse permanently lame or cause death. Laminitis is caused by abrupt changes in the feeding or exercise regime, changes in pH in the large intestine, certain medications, starch or fructan overload of the gut (Davidson and Harris 2007; Cuddeford 1999). In other words, the majority of cases of laminitis are directly related to the nutrition the horse receives.

Another typical digestive disorder is stomach ulcers, recorded in up to 90% of the population of performance horses (Sykes et al. 2018; Andrews et al. 2005). Caused by fasting, stress or diets with an excess of starch (Andrews et al. 2015; Sykes et al. 2018; Luthersson et al. 2009), symptoms may include signs of discomfort and bad humor, weight loss, lack of appetite, teeth grinding and other vices (Videla and Andrews 2009; M. Murray et al. 1989). If the ration and management is not changed during and continued after veterinary treatment, re-incidence of this pathology is extremely high (Luthersson et al. 2017 and 2019, Kerbyson et al. 2016).

These pathologies, directly related to equine nutrition and management, are serious and can result in the long-term illness or death of the horse. They are clearly and directly related to horse well-being. Studies have recorded, through veterinarian reports, the statistical incidence of these and other pathologies in domestic horses. Use of modern technology, “Big Data systems” and the use of identification microchips would make it possible to compile this information to contrast groups of populations against base welfare statistics to identify patterns of incorrect management or abuse.

XI. VICES, STEREOTYPIES AND HORSE WELFARE

One of the “Five Freedoms” that define horse welfare is “freedom from distress.” Many causes of distress are directly related to feeding practices of domestic horses. Anxiety, boredom, solitude and tension, sometimes linked to stressful weaning (separation of the mare from the foal), or competitive feeding environments or incorrect levels of nutrients in the diet, are related directly to vices or stereotypies (Nicol 1999). Weaving, coprophagy, pawing or cribbing are all common vices in the horse.

Horses do not eat meals or compete aggressively for forage in the wild (Harris 1999; Berger 1986, 158-159; Rubenstein 1986). Weaning the feral foal is done when the mare is gestating the next foal. Milk is no longer provided; the mare turns away and does not give the foal access, but there is no social separation within the family unit. Crib biting and wood chewing are not seen in feral horses. This is clear proof that stabling practices can cause these vices and are directly related to the welfare of the horse (Wickens and Heleski 2010).

Vices usually become chronic, so prevention is the key. These vices are long-term and have a serious effect on the well-being of the horse. Horses with vices have problems maintaining their weight, suffer more colics and wear down their teeth to the point that they cannot chew properly.

Management strategies to prevent the problems should be introduced. Actions like turning the horse out, ensuring that the horse has constant forage intake available, or giving the horse a stablemate become key to reducing or controlling these serious problems (McGreevy and Nicol 1998; McGreevy et al 1995; Marsden 1993).

XII. HOW TO DEVELOP A DASHBOARD OF EQUINE WELFARE INDICATORS

Although there are no longer herds of wild horses, there are multiple groups of feral equines that have been studied and can be easily studied in the future. Care must be taken with the protocols used when conducting these investigations. Feral horse populations often fall under unclear legal circumstances. Lack of stability in the herds can lead to incorrect or misleading study results. For example, feral herds are often made up of both feral and semi-feral horses. When the owners of the semi-feral horses take their horses away for personal use, the herd populations become unstable and the feral horses become accustomed to interaction with humans. Their behavior can no longer become considered strictly “feral.” It becomes almost impossible to develop study protocols that will be accepted as providing statistically significant results.

If we combine the studies on feral equine herds and contrast them with studies of domestic equines, it is clear that there are certain concepts that we can accept as true right now and can logically be used to make practical suggestions related to horse welfare. Care must be taken to maintain a flexible, transparent environment related to the decision-making process for posterior adjustment when new information becomes available. Reviewing and possibly incorporating new research should be done regularly. For example, the following are some typical habits that have been observed in feral and domestic horses:

Horses are social animals and maintain relatively stable groups (Heitor et al. 2006; Keiper and Receveur 1992; Keiper 1988).

Horses consume high amounts of fibrous, nutrient-poor forage in numerous feeding bouts, during an average of 13 or 14 hours per day (Ellis 2010).

Feral horses do not compete aggressively among each other for feed (Berger 1986; Rubenstein 1986).

Horses interact among each other, grooming, socializing between feeding bouts (Heitor et al. 2005; Keiper and Receveur 1992; Keiper 1988).

Horses are active throughout the day and night, resting during only short intervals (Ellis 2010).

If allowed ad lib access to forage, horses will eat between 1.8% and 3% bodyweight (Dulphy et al. 1997; Kern and Bond 1972), as expressed in Dry Matter (DM).

Horses ingest large amounts of water in short periods of time and will drink between 25 and 40 liters of water per day, depending on the ambient temperature and the level of physical activity (Cymbaluk 2013).

As can be seen, many of the habits of feral and domestic horses are related directly to their daily nutrition and nutrition management. While respecting natural nutrition habits will not solve every welfare question, these well-studied behaviors can be used as a base to develop strategies to improve horse welfare.

XIII. CONDITION SCORING AND HORSE WELFARE

The easiest way to begin an equine welfare evaluation is to objectively assess if the horse is fat or thin. The fat deposition or lack thereof will depend on how much energy the horse receives and if that energy is from a source that can be absorbed by the equine digestive tract. If a horse receives appropriate energy levels in the diet, it will maintain a correct body condition.

Too much energy will increase the horse’s weight to above a healthy level. A lack of energy will reduce the horse’s weight and body condition, which eventually will lead to malnourishment. The digestibility of the energy source is important. If the feedstuff is not digestible, although the horse will receive calories, it will not be able to absorb them.

There are several formal systems used to objectively assess equine body condition. Body condition scoring is the technical term that refers to applying a number to define the deposition of fat and muscle in the horse. The Henneke body condition scoring system, one of the most well-known methods, was developed by Don Henneke in the University of Texas A & M in 1983 (Henneke et al. 1983). This system scores the fat deposition of a horse on a scale from 1 to 9. 1 refers to an emaciated horse, 5.5 or 6 would be typical for a pleasure or a competition horse, while 9 would be defined as an obese animal. As this Henneke score is often used in scientific studies, using the same system throughout makes it is easier to transfer scientific studies to practical applications.

The body condition of feral horses varies greatly depending on the season and the availability of pastures (Irvine and Alexander 1994). In the spring and fall, these horses will gain body condition, taking advantage of pasture growth and growing sometimes quite fat. During the winter they will become thin if there is a lack of forage. The feral horse’s metabolism changes according to the season to conserve energy during the cold months (Irvine and Alexander 1994). It is possible that our current stabling systems, which maintain the horse’s condition score throughout the year, may interfere with this annual biological rhythm and may affect horse health as related to insulin resistance. Most horses are considered healthy with a condition score between 5 and 7 with small variations according to their specific situation related to growth, breeding, gestation, lactation or sport (Henneke et al. 1983).

The first indicator in a welfare check is the condition score of the horse.

Photo by Coby Bolger.

Body condition scoring is commonly used by humane societies, law enforcement officers and legal courts in the United States as an initial indicator for horse welfare. A body score of less than 3.5 without a certificate that the horse is under veterinary treatment constitutes a clinical sign of malnutrition with suspicion of neglect. The horse can be confiscated to a rescue center or put under mandatory veterinary care.

Formal training and practice are needed to correctly evaluate an equine condition score. The fat deposition of the entire horse must be taken into account. Like humans, horses can accumulate fat on their necks or hindquarters, but lack condition or muscling in other areas. Foals under eight months accumulate fat first on the withers and hindquarters. The ribs are often visible in small foals even when they are in good condition. Some breeds or very fit horses may appear fat or thin, but this may be normal for their body type. Unless the horse is clearly malnourished or obese, it is usually necessary to physically palpate the horse to make the best determination on its condition score.

Condition scoring requires training and experience.

Photo by Coby Bolger.

There have been cases recorded of overzealous horse protection volunteers that have unfairly accused horse owners of neglect or mistreatment through lack of experience (Henneke 2012).

It would be interesting to investigate the possibility of using Big Data capabilities or even automatically triggered sensors to objectively evaluate condition scores. There is a legal requirement in many countries to identify equines by microchip, so it would be relatively simple to develop a system that would automatically communicate with a horse owner, if their horse were identified with an inappropriate condition score. An automated, non-intrusive system to evaluate condition scoring would be useful in monitoring the well-being of feral horses in the winter.

XIV. HOW MUCH DOES A HORSE EAT?

An adult horse will ingest a total ration of between 1.8% and 3% of its live bodyweight as expressed in dry matter (DM) (Bolger 2013, 68). What type of feedstuff the horse will eat will depend on what is available. If the horse is feral, it will choose different grasses and plants throughout the day and night. If the horse is domestic, its diet will be controlled by its owner, stable owner or trainer.

The domestic horse should receive as much of the diet as possible in pasture, forage or fiber. Many horses live perfectly well on a diet of 100% forage. The minimum daily amount of fiber in the diet should be 1.5% of its bodyweight, measured in dry matter (DM) (Dugdale et al. 2010; Harris et al. 2013; Harris and Geor 2014). Unless the horse has excess body condition, ad lib forage available throughout the day is recommended. Straw is not considered an acceptable base of forage for horses. Straw increases the risk of impaction colic and gastric ulcers (Luthersson et al. 2009).

An efficient management strategy to allow ad lib access to forage, preventing waste and maintaining hygiene.

Photo by Coby Bolger.

If it is necessary to provide cereals to increase energy levels to meet the horse’s activity requirements, the maximum amount of cereals the horse should receive is 1% of the total bodyweight or a maximum of 2gr/kg bodyweight of starch per day (as expressed in dry matter) (Sykes et al. 2018). All cereals, except oats, should be heat processed in order to be absorbed efficiently by the horse’s digestive tract (Vervuert et al. 2007; Julliand et al. 2006; McLean et al. 2000; Granfeldt et al. 1994). Cereals are high in soluble carbohydrates and should be used sparingly in the diet (Luthersson et al. 2009; Nadeau et al. 2000).

When checking an equine installation, if the horses have no access to pasture, it is easy to calculate if there is enough forage on the premises to feed the horses and for how long. The average weight for an adult horse is around 500 kg. If the horse eats a minimum of 1.5% of its bodyweight in forage, every animal will eat a minimum of 7.5 kg per day. An average size bale of hay will weigh between 18 to 25 kg, so a bale will last around 3 days per horse. It is easy to extrapolate how much hay you have and how much hay you will need.

It is easy to evaluate and weigh hay to calculate how many bales will be required.

Photo by Coby Bolger.

XV. HOW CAN WE DETERMINE A HORSE’S WEIGHT?

When expressing amounts for equine diets, we refer to an amount in kilograms of feedstuff in dry matter relative to a percent in bodyweight (NRC 1989). For example, a 500 kg horse will eat 1.5% of its bodyweight in fiber per day, so it will eat 7.5 Kg (DM) of hay per day. This means that a horse owner needs to know how much their horse weighs to correctly estimate the horse’s diet. Luckily, there are several methods for weighing domestic adult horses. Any horse owner, veterinarian or manager can estimate their horse’s weight in minutes to correctly estimate the horse’s feed ration.

Mobile live animal scales weighing as little as 70 kg are available for use in large stables. This is the most effective method for weighing a horse.

There are also several mathematical formulas for estimating a horse’s weight. A common formula is: BW (kg) = CG3 x 80, where CG refers to the heart girth or thoracic perimeter in cm after respiratory expiration and the number 80 is constant (Marcenac and Aublet 1964).

A standardized weight tape is an inexpensive solution to estimating an adult horse’s weight (Ellis and Hollands 2002). Studies have been conducted to compare the weight tape results against live animal scales with good results (Ellis and Hollands 1998). It should be noted that weigh tapes cannot be used effectively with ponies, broodmares or foals of under twenty-four months (Gee and Harris 2005). If the horse has a non-standard conformation, the weigh tape weight estimate will be less reliable (Gee and Harris 2005).

Photo by Mars Horsecare (2002).

Although there may be slight discrepancies in estimating the weight of the horse with a weigh tape, if the owner observes the weight in combination with the body condition score over time, the diet can be correctly adjusted when necessary. Taking into consideration the varying nutritional contents in feedstuffs, different workloads, variable metabolisms between individuals and breeds, weight estimation is used as one of several tools to better understand the total nutritional picture. A good rider or competent owner will learn to understand the subtleties of ration adjustment with time and experience.

Daily hay rations should be weighed and calculated according to the horse’s weight.

Photo by Coby Bolger.

XVI. BASIC FUNCTIONS OF THE HORSE’S DIGESTIVE TRACT AND THE RELATIONSHIP TO EQUINE WELFARE

1. The equine mouth and esophagus

The digestive process begins in the horse’s mouth. The horse’s lips are mobile and able to select different plants according to preference and availability (Harris and Dunnett 2018). The horse’s circular chewing pattern, head position when eating as well as the horse’s strong jaw is well adapted for crushing fibrous forage into small particles.

Equine teeth are anchored firmly in the jaw, and continually erupt and wear down with the constant chewing throughout the life of the horse (Easley et al. 2011, 4, 9). This wear can provoke the formation of hooks, protrusions or sharp edges (Dixon and Dacre 2005; Easley and Caddel 1991) that may irritate the tissue in the horse’s mouth or limit the horse’s capacity to grind foodstuffs into small particles that will be efficiently digested (Carmalt 2007; Pagliosa et al. 2006; Dixon and Dacre 2005). Eventually, in an older horse, the teeth may wear away to the point where the horse is unable to chew certain feedstuffs (Ralston and Harris 2013, 290).

Periodic evaluation and care by an equine dentist or specialized veterinarian, and in some cases, the introduction of alternate feedstuffs may be necessary to ensure comfortable chewing patterns, especially for the senior horse.

Senior horses with dental issues can be managed with fiber-based mash type diets that require little to no chewing.

Photo by Coby Bolger.

Unlike humans, the horse only produces saliva when chewing (Durham 2009; Luthersson et al. 2009; Elia et al. 2010). Saliva acts as a pH buffer and is needed to coat each feed particle for the formation of a feed bolus (Al Jassim and Andrews 2009; Elia et al. 2010). We can confidently state that the horse needs to chew feedstuffs for as much time as possible to produce as much saliva as possible.

Chewing time for different feedstuffs has been measured in several studies (Ellis 2010; Müller 2009; Ellis and Hill 2002; Meyer et al. 1975, 1986). The average chewing time for 1 kg of hay and other long stem types of forage takes some 40 minutes to chew and will produce between 3 and 4 liters of saliva (Ellis 2010; Frape 2004, 2; Carson and Wood-Gush 1983). Fiber with higher fiber content requires longer chewing times. The average chewing time of only 5 or 10 minutes for 1 kg of oats will produce only limited amounts of saliva (Ellis 2010; Frape 2004, 3; Carson and Wood-Gush 1983). This is detrimental to the digestive process and can result in feedstuffs that are not absorbed in the digestive tract.

Satiety, if the horse feels “full” or satisfied with the diet, is also related to feeding time (Wilson et al. 2007; Willard et al. 1977). Horses are defined as “trickle-feeders” who ingest small amounts of fibrous feedstuffs in numerous feeding bouts for around 13 to 15 hours per day (Ellis 2010).

If the feedstuff has been efficiently broken down in the mouth and each particle is covered in saliva, the feed bolus will pass easily through the esophagus and arrive to the stomach, ready to be further broken down and absorbed into the digestive tract.

2. The equine stomach

The size and shape of the stomach is similar to a rugby ball, with a constant presence of acid in the bottom portion, known as the glandular area. Proportionally to the size of the horse, the stomach is small. For a 500 kg horse, the typical capacity of the stomach is only 5 to 15 liters (Auer and Stick 2012, 22; Nickel et al. 1979). The size and function of the stomach lends itself to the constant entry of fiber, typical in the diet of a feral horse.

Forage, as mentioned earlier, is ingested slowly and so arrives in small quantities to the stomach to be efficiently broken down for digestion. The equine stomach is adapted to receive small amounts of food constantly (NRC 2007) and it is rare for the stomach to be absolutely empty (Santos et al. 2011; Jansson 2013).

The speed with which a horse can ingest cereals or other commercial feeds is a crucial factor. If such food is provided in large amounts and ingested too quickly, it can overfill the stomach increasing the risk of colic and other digestive pathologies (Davidson and Harris 2007). The human habit of several meals eaten quickly during the day is not appropriate for horses because of the physiology of the digestive tract.

Due to the presence of the cardiac sphincter at the entrance of the stomach, vomiting or reflux is a very rare occurrence (Al Jassim and Andrews 2009; Davidson and Harris 2007). It is important that the horse does not ingest poisonous feedstuffs, as they cannot be easily eliminated.

The main trigger of the increased release of gastric acid is the hormone gastrin (Campbell-Thompson and Merritt 1990). It is believed that the release of gastrin is produced by the stimulus triggered by the stretching of the stomach wall (Sandin et al. 1998), which is an effective design if we take into account the constant ingestion of horse forage in the wild (M. Murray and Grodinsky 1989).

The secretion of acid continues even when the stomach is empty (Hembroff 2006; Lester 2004; Merritt et al. 2003; Campbell-Thompson and Merritt 1990). Although the tissue in the glandular portion of the stomach does have some protection, the very low pH and constant presence of acid makes it necessary for the horse to avoid fasting (Feige et al. 2002; M. Murray and Eichorn 1996). Also, the use of pH base feedstuffs or feedstuffs with high calcium content, such as alfalfa, has been suggested to reduce the risk of gastric ulcers (Lybbert et al. 2007; Nadeau et al. 2000).

If the stomach is empty when the horse is active, the pressure caused by the movement of the cardiorespiratory system can push acid into the non-glandular region (Lorenzo-Figueras and Merritt 2002; Royn et al. 2005; Orsini et al. 2009). The tissue in this area of the stomach is more delicate than the glandular area, so contact with stomach acid can cause damage. As little as 250 g of fiber ingesta, before physical activity, can form a protective barrier between the glandular and non-glandular area of the stomach, thus reducing the risk of non-glandular ulcers.

As little as 250 gr of fiber will create a “mat” between the stomach acid present in the glandular area of the stomach and the sensitive non-glandular tissue.

Photo with permission from Dr. Nanna Luthersson (Hestedoktoren, Denmark).

3. The small intestine

The feed ingesta in the stomach then passes into the small intestine. This organ, which measures some 20 meters in length and is very narrow, is the site of rapid, enzymatic based absorption of the energy provided by the starch and oil in the horse’s diet, as well as the amino acids and some vitamins and minerals (Coenen 2013; Zeyner and Harris 2013).

The feedstuffs will pass through the small intestine quickly, in approximately 60 to 90 minutes (Julliand et al. 2006). This speed makes the horse singularly maladapted to absorb large amounts of starch from cereals in the diet. Simply put, a horse in the wild has never found 2 kilos of oats on the ground for it to eat all at once.

In order for the horse to properly absorb the nutrients, it is of upmost importance that the feed arrives to the small intestine in small amounts after having been efficiently broken down into small particles by the horse’s teeth, the digestive enzymes present in the saliva and the stomach acid. Otherwise the undigested particles will pass into the hindgut and the nutrients will not be absorbed.

Studies have been carried out that confirm the presence of the digestive enzymes lipase, with small amounts of amylase and trypsin, among others (Gore et al. 2008, 370; Lorenzo-Figueras et al. 2007; Hembroff 2006; Frape 2004, 15; Kienzle et al. 1994). This provides the horse with the ability to digest certain feedstuffs better than others. For example, the relatively small amount of amylase suggests that the horse is not able to tolerate large amounts of starch in its diet (Hinchcliff et al. 2008, 309; Richards et al. 2004; Cuddeford 1999).

The activity of the enzyme related to the absorption of lactose, lactase, decreases with age and from about four years of age is non-existent in the equine digestive tract (Roberts et al. 1973). That is, the adult horse will no longer efficiently digest dairy products and, if included in the diet, can cause digestive upset.

Lipase, the enzyme necessary to absorb oil as an energy source, is present in sufficient amounts to allow the horse to efficiently convert oil into energy (Lorenzo-Figueras et al. 2007). However, studies have shown that it will take up to twelve weeks for the horse to adapt to an oil-based diet and efficiently metabolize the energy (Dunnett et al. 2002).

Blood testing and analysis of CO2 exhaled by the horse during exercise can increase our understanding of how horses can metabolize different feedstuffs as energy sources.

Images supplied with permission from Kentucky Equine Research.

Amino acids, the building blocks for protein, are absorbed in the small intestine (Almeida et al. 1999). Some amino acids are produced directly by the horse, and others, known as essential amino acids, must be provided in the horse’s diet. There are ten essential amino acids. If there is a lack of one or more amino acids in the diet, proteins cannot be formed and the amino acids will be excreted without being utilized by the horse (Almeida et al. 1999). An excess of protein is innocuous and eliminated through the urine.

Microvilli, small fingerlike protuberances in the digestive tract, increase the absorption surface, located in the epithelia. These allow the effective absorption of the nutrients from the ingesta into the bloodstream. The microvilli are fragile and can be damaged by substances like lectins (Weinman 1989), contained in raw beans, or wheat germ agglutinin and many other causes. This accelerating cell loss or shortening of the length will diminish the efficiency of nutrient absorption. The epithelium is renewed every four to five days in healthy animals. However, studies have shown that severe or repeated mucosal injury may seriously harm the horse and increase the risk of digestive pathologies (Blikslager et al. 2018).

4. The equine hindgut or large intestine

The hindgut, also known as the large intestine, is made up of two major compartments, the caecum and the colon, and acts as a complex fermentation vat, storing large amounts of water in combination with a complex microbiota (Julliand et al. 2016). The hindgut comprises around 60% of the entire digestive tract (Al Jassim et al 2009) and serves to absorb structural carbohydrates like cellulose and hemicellulose found in fresh grass, hay and other fibers (Al Jassim and Andrews 2009; Stevens and Hume 1995, 22).

The microbiota is the combination of bacteria, fungi, virus and mold found throughout the body of horses and humans as well as other animals (Julliand and Grimm 2016, Edwards 2019). The microbiota is specific to each individual and a diverse aerobic microbiota is directly related to the health of the organism (Hooper et al. 2012). The microbiota is passed from the mother to baby, or from the dam to the foal. The microbiota is specific to the environment and diet received (Varloud et al. 2007).

Although the microbiota, known as “the forgotten organ” (O’Hara et al. 2006), is only in the initial phase of investigation, we do know that a robust microbiota is related to a strong immune system (Hooper et al. 2012). The microbiota of the horse is concentrated in the hindgut, producing energy in the form of volatile fatty acids and several types of vitamins, especially the full range of B vitamins (Julliand and Grimm 2016; Zeyner and Harris 2013).

The microbiota, each organism with its own DNA, is sensitive to variations in diet, to changes in the pH, heat, stress or certain medications (Costa et al. 2015). An unstable microbiota can directly cause numerous digestive problems resulting in sickness or the death of the horse animal (Santos et al. 2011; Drogoul et al. 2000; Julliand et al. 2001; Frape 2004, 125; Clarke et al. 1990; L.D. Lewis 1995; Harris 1999). Small details in the daily routines of equine feeding and management contribute to a balanced microbiota. The quality of fiber that the horse receives and the hydration status are also important factors to take into account.

Starch based feedstuffs (like oats, barley or corn) that pass into the large intestine undigested, will destabilize the pH, producing a chain reaction through the production of lactic acid that sets off an alteration in the microbiota that, in turn, can lead to colic, laminitis or diarrhea (Pollitt and Visser 2010; Al Jassim and Andrews 2009; Durham 2009; Julliand et al. 2001; Harris 1999; L.D. Lewis 1995; Clarke et al. 1990). This underlines the importance of the quality and type of feedstuffs provided and the efficiency of the rest of the digestive process.

If the horse cannot chew its food properly, or if, because of overfeeding of cereals or fasting cycles, the feedstuffs with high starch content cannot be properly absorbed in the small intestine, the undigested starch will pass into the large intestine and damage will occur to the microbiota (Drogoul et al. 2000; Julliand et al. 2001).

Correct motility is also of crucial importance to the health of the horse. Rhythmic contractions in the hindgut serve to mix the feedstuffs with the microbiota and move it through the digestive tract (Jansson 2013). The speed of the contractions varies according to the ingestion of feedstuffs. Once again, fasting cycles and feeding times will affect the motility in the digestive tract (Jansson 2013).

5. Other details about the equine digestive tract

5.1. Hydration of the horse

Dehydration, even at subclinical levels, will result in less water available for the production of saliva or for storage in the large intestine. This will negatively affect the horse’s microbiota and be detrimental to nutrient absorption. Risk of colic due to impaction or the inability of the digestive tract to move the ingesta will increase even if the horse is only slightly dehydrated (Archer and Proudman 2006).

As previously stated at the beginning of section XI., a 500 kg horse will ingest between 25 liters to 40 liters of water per day, depending on the environment and activity (Cymbaluk 2013). Horses have a preference for the temperature of the water. If the water is too cold or hot, some horses will drink less (Cymbaluk 2013). As horses are prey animals, they drink large quantities of water in very short periods of time. Modern automatic waterers are designed in many cases incorrectly and do not allow the horse to drink naturally.

Horses should be checked every day for signs of dehydration and the hydration status should be monitored during hard work. The easiest way for a non-veterinarian to assess the hydration status of the horse is to execute a “pinch test.” This refers to the practice of pinching a small piece of skin on the neck or shoulder area of the horse. If the skin stays “tented” for more than a few seconds, the horse is around 5% to 7% dehydrated. There are differences between horses as individuals so the horse owner should be familiar with the horse (Adam 2012).

Another procedure for checking the hydration status is to observe the capillary refill in the horse’s gums. The horse’s gums should be pink and moist. If you push your thumb against the gums, a white spot will appear, but the color will return quickly. If the gums do not return quickly to the normal color, the horse is seriously dehydrated (Adam 2012).

Procedures to re-hydrate a horse are to offer it water (electrolytes should not be offered to a dehydrated horse) or feedstuffs that contain water, for example, haylage or mashes. In emergency situations, the veterinarian can rehydrate the horse using fluid therapy (Adam 2012).

5.2. The relationship between the well-being of the gut and physical activity

Movement is of utmost importance to maintain gut motility. The horse’s entire digestive tract shifts rhythmically like a pendulum as the horse walks, trots and canters. This aids in transporting the ingesta through the gut and so prevents colic. Although this has not been well studied, we do know that statistically the stabled horse runs a higher risk for colic, laminitis and other digestive pathologies because of this lack of movement.

Veterinarians always refer to more calls related to digestive problems on days off and holidays. Horse owners sometimes use automatic horse walkers or turnout in small paddocks to solve this problem and it will help with certain horses. But other horses require more vigorous activity to avoid digestive problems.

5.3. Social contact and digestive pathologies

Horses are social animals. Feral horses live in stable herds for long periods of time (Heitor et al. 2006; Keiper and Receveur 1992; Keiper 1988). Gastric ulcers, shown in some studies to affect more than 90% of the performance horse population (Sykes et al. 2018; Andrews et al. 2015), are believed to be reduced when the horses interact with other horses.

Even stallions, who can be more difficult to manage, can be socialized. It may not be possible to turn out all horses in groups to have unlimited direct physical contact, but stables and paddocks can be built in such a way that the horses have direct eye contact and partial physical contact. It is true that there is a risk of injury related to kicks, bites and accidents related to aggression, especially if the horses are shod. This risk should be intelligently managed so that the horses can participate in daily safe social interaction. Group housing and pasture distribution can be developed to optimize safe social contact.

This haynet design is an example of a strategy to allow constant slow intake of fiber in a social non-competitive environment.

Photo by Coby Bolger.

It is easy for humans to underestimate the stress of travel or change of social circle or stables on horses. Owners often only notice this stress when the horse stops eating, loses weight or is diagnosed with an ulcer.

Some equids, such as mules, are stoic in nature, so identifying stress can be quite difficult. Some horses will show no outward signs of stress or the signs are so slight as to be imperceptible, unless the horse falls ill. An important aspect of correct horse management is to introduce solutions (like maintaining the social circle, or introducing familiar routines during travel) that help the horse cope with change and thus reduce the risk of digestive upset.

Daily free movement and social contact with other horses will reduce risk of digestive pathologies.

Photo by Coby Bolger.

XVII. WHAT IS THE DIFFERENCE BETWEEN A COMPETITION HORSE’S DIET, A PLEASURE HORSE’S DIET AND A FERAL HORSE’S DIET?

Like the feral horse, or any pleasure horse, the competition horse or racehorse’s diet must be based primarily on forage. The only difference between the animals is the variation on the amount of energy, the type of energy and nutrients needed in the diet. That sounds like a big difference, but in reality, it is an adjustment in the proportions in the diet. The feedstuffs themselves do not vary much.

Growing horses that are bred for competition or racing will need higher levels of certain nutrients like copper, manganese and zinc plus good quality protein to promote maximum growth and to aid in the formation of bone (NRC 2007). Lack of certain nutrients like biotin will result in problems related to, for example, hoof quality (NRC 2007).

A feral horse does not have the same body size, and is not required to do the same physical activity or cope with the same levels of stress. As long as they have sufficient quantity of a diet based on a wide range of fibrous plants and plenty of water, they will do fine.

Hoof quality of the feral horse is generally quite good, even though they have no access to fancy feeds and supplements. Good multi-plant forage has enough digestible protein and nutrients to maintain hoof quality. The other essential requirement for good feet is constant movement over different terrain to stimulate hoof circulation. From that perspective, of course, the feral horse lives in idyllic circumstances.

When a horse is competing, it will expend a higher amount of energy and be subject to higher stress levels (NRC 2007). The constant contact with other animals, bacteria, virus and parasites is also a stress on the immune system. The owner will have to source forages with higher energy contents, for example, hays cut closer to flower than seed, sugar beet fiber or soy hulls to add to a balanced base diet. Oil and starch sources like oats can be supplemented if needed to increase the horse’s energy to maintain a correct body condition score. Vitamin and mineral levels will have to be adjusted. Minimum and optimal nutrient levels are discussed in numerous research publications worldwide and easily available to the public.

Equine nutritionists encourage riders and breeders to always test their forage for nutrient levels and total energy to then be able to calculate the correct nutrient and energy levels of the ration.

Feed manufacturers, or at least the feed manufacturers who produce higher energy feeds for equids in hard work, will supply the energy level of the feed, expressed in kilocalories and megajoules per kilo DM as well as the soluble carbohydrate level (expressed as starch, sugar or water soluble carbohydrates) to understand the glycemic index of the ration, which can affect the capacity of the horse to carry out different types of exercise. An owner or rider with the correct training can gather the information and calculate the correct ration, or an equine nutritionist can supply that service.

Some feed manufacturers supply computer generated ration calculation tools for free on-line (KER MicroSteed and Cavalor FRASC).

A typical diet evaluation for a 550 kg horse in medium work receiving a ration consisting of alfalfa hay, meadow hay, corn, oats and barley. The diet is calorie dense, but does not supply a correct level of micro-nutrients and vitamins.

Used with permission of Kentucky Equine Research.

There are endless amounts of supplements available for the horse, but in general, a good fortified base diet formulated to respect current scientifically defined nutritional levels is sufficient. In certain circumstances related to stress, for example, when the horse travels or is stabled in unfamiliar environments, anti-oxidants can be added into the diet to support the immune system. If the horse is sweating while working, electrolytes can be added to the ration.

It must be noted that the rules for feeding are exactly the same among all horses, whatever their activity. If you can keep your horse busy eating a base of good quality forage for most of the day, maintain activity and social behavior, adding only the extra energy and nutrients required for health and energy expenditure, most of the battle is won.

Social management may be a bigger challenge for the competition horse. A good manager will maintain the horses within their familiar herd even while travelling in order to reduce stress. Many riders will travel with several horses to shows and stable them together.

Riders form a part of the horse social herd during competition. Many riders will set up table and chairs around the stables and spend quite a lot of time with their horses to maintain a familiar climate and to reduce stress for everyone. Stable doors can be left open, using leadropes or cloth barriers to allow the horse to look out. All of this reduces nerves and lowers the risk of digestive upset.

Riders will organize themselves at a show to promote social behavior, avoid fasting and to reduce stress.

Photo by Coby Bolger.

It is important to understand the role of fitness for the competition horse, although I will not undertake to explain the details of this complex correlation in the present text. Horses should not enter into fatigue when competing, so physical fitness is deemed vital to horse well-being. A correct diet is not an effective solution to a lack of fitness.

It is estimated that a fitness cycle takes between four to seven months, depending on the horse’s age, discipline and level of activity (Steinkraus 1997, 99). The energy levels and nutrients in the diet should be adjusted throughout to accompany the fitness process. There are numerous systems available to evaluate equine fitness. Pulsometers, specialized software and lactic acid testing have been calibrated to be used by equine exercise specialists.

Riders can use pulsometers while they are working the horse to evaluate the horse’s effort and fatigue levels.

Photo by Coby Bolger.

XVIII. IN SUMMARY

We live an existence of privilege that allows us the luxury to ponder questions related to humanity and our responsibilities to the flora and fauna around us. Our relationship with horses is part of this reflection.

We must recognize that the human brain is good at certain tasks and limited at others. Specifically, our brains are rather faulty when it comes to objective decision-making and so we have to question our underlying assumptions and bias (Kahneman 2012, 1). It is important to incorporate tools that allow us to correctly interpret information and objectively look for solutions, thus overcoming our tendency to jump to conclusions according to subjective interests.

Many of the characteristics that define equine well-being are related to nutrition and nutrition management. We can use the physiological characteristics of the equine digestive tract and eating behavior of the feral and domestic horse to set forth some simple recommendations to ensure horse welfare and improve horse well-being in all environments. If we insist on proactively and transparently using scientifically contrasted studies to support these recommendations, riders can ensure the treatment of their horses is optimized and officials and legislators can make intelligent decisions, thus avoiding political landmines related to the opinions of different interest groups. These welfare indicators can be used for educational purposes for owners and riders, or as a guideline to develop well thought-out legislation that will protect the domestic and feral equid now and in the future.

Equine nutrition studies provide an initial base of information for these recommendations, but other information related to behavior and health will need to be utilized as well. A round table of technical experts from all areas of study with access to the latest research should work to develop a full range of welfare indicators with a schedule of periodic reviews to continue the process on an ongoing basis.

Indicators should be developed for different aspects of horse welfare; for the horse on an individual level; for hygiene, health and nutrition parameters, as well as for minimum requirements and “grading systems” for equine installations, paddocks and means of transport.

An initial list of checkpoints related to equine nutrition and nutrition management could be the following:

(i).- Dietary rules:

Horses should receive a base diet of between 1.5% and 2.5% of their bodyweight DM in digestible forage.

Horses should have unlimited access to fresh water.

Cereal rations should be provided sparingly to provide starch-based energy only when necessary.

Cereal based rations should be spaced throughout the day in quantities not over 2 to 2.5 kg per meal to avoid overwhelming the stomach and lowering the pH (for a 500 kg adult horse).

If a horse requires cereals in its diet, it should not receive more than 2 gr of starch per kg bodyweight per day as a maximum and not more than 1 gr of starch per kg bodyweight per meal.

If a horse requires cereals in its diet, it should not receive more than 1% of their bodyweight in cereals per day divided in several meals.

If a horse requires cereals in its diet, the cereals (except oats) should be cooked or heat-treated in some way to increase the digestibility of the starch.

Horses should not fast for more than 3 hours.

The horse requires a diet based on slow-intake forage and should not be subjected to human meal times or a competitive feed environment. Small quantities of forage should be provided throughout the day and night to mimic natural eating patterns.

Changes of the diet should be introduced slowly over a 15-day period of time in order to maintain a stable microbiota.

(ii).- Requirements related to equine well-being and the diet:

Horses should be between 4.5 and a maximum of 7 on the Henneke Conditon Scale.

There should be no sign of dehydration. Horses should be checked on a daily basis with the skin “pinch test.” The horse’s teeth should be inspected regularly by a trained technician. Records should be kept for each horse in the stable.

The horse owner should be aware of how much the horse usually eats and drinks, in order to note variations that may be caused by illness or distress.

If the horse has some “vice,” such as weaving or cribbing, strategies must be introduced to reduce the problems. For example, keeping the horse busy with sufficient fiber in the diet and ensuring that the horse has plenty of access to social interactions with herd mates.

(iii).- Requirements for a stables and equine management:

Stables and paddocks must be large enough to permit free movement.

Another horse should be stabled on the premises and within eyesight.

Horses should be allowed daily social interaction with other horses to reduce stress.

Horses should have access to daily vigorous physical activity to help with digestive motility.

Horses eat approximately 2% of their bodyweight in a combination of forage and possibly some type of feed (expressed in dry matter). Sufficient forage should be present in the stables, either in the form of pasture or hay.

Water should be provided at all times in drinking sources that allow for natural drinking behavior.

I have never met a horse owner or rider who did not aspire to treat its horses well. Equine and animal well-being is fast becoming a political flashpoint. We will need to develop balanced strategies to come to decisions and forge an ethical way forward. In my opinion, certain decisions are relatively simple, as there is a general level of consensus based on a solid underpinning of investigation. As scientific research is constantly providing us with new information that can be incorporated into our foundation of knowledge, we must be careful to develop procedures that will allow professional workgroups to monitor these new investigations and to adjust existing recommendations or incorporate new ones, once consensus is met.

Equine nutrition contributes a good base for horse well-being, but it is not the only topic that needs to be taken into account regarding horse welfare. The best way forward is to incorporate experts with a direct relationship to the field of equine studies such as ethologists and veterinarians.

Horses, at some point, decided to cooperate with humans. We do not know if this was a conscious decision or a lucky stroke of fate for both of us. We cannot yet determine how happy the horse is with its lot, but it is clear that humanity does not have the same relationship or fascination with other equids, like zebras or other ungulates, like antelopes. Our collaboration with the horse is unique and not destined to disappear anytime soon.

Going forward, as humans wrestle with the meaning of our existence, it now comes time to defend horses’ rights to decent treatment and intelligently safeguard their well-being. Human beings can now physically survive without horses, but in our hearts and souls, a world without an alliance between horse and human would be a lesser world. Humanity’s twenty-first-century challenge is clear. We must aspire to meet the challenge of ethical and respectful treatment of horses, all living creatures and our planet.

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NOTAS:

(1).

(2). http://www.oie.int/index.php?id=169&L=0&htmfile=chapitre_aw_working_equids.htm