A-Z of nutrition and ingredients

By Clare MacLeod

Ad lib: describes feed given in a free choice manner so there is always some left when the next portion is fed.

Aloe vera – the gel from the large fleshy leaves of the aloe vera plant, which are reputed to have health benefits when used both externally and taken as an oral supplement. Used for wounds, especially burns, and for soothing effects on the gut.

Amino acid: a building block of protein, of which there are twenty five. Ten of these are known as essential, because they must be supplied in the diet. The others – non-essential – can be synthesized in the body from the essential ones.

Antioxidant: a substance that has a neutralising effect on harmful pro-oxidants in the body. Oxidation is a normal part of metabolism, but too much is harmful to body tissues. Some vitamins and many plant components are antioxidants.

As fed – describes a feed as it is fed, fresh, rather than on a dry matter basis (with all the moisture removed). Most feeds – even dried – contain some moisture, e.g. hay is typically 88% dry matter, so as fed, 1 kg of hay provides 880 g of dry matter (actual hay) and 120 g of water.

Ash – an analytical component, which is the residue of a feed after it is burned at very high temperatures. Ash reflects the mineral component of the feed.

Balanced diet – a diet that provides all the essential nutrients every day in just the right amounts, with no net gain or loss. For most horses, diets are balanced by adding nutrients missing from the forage, which makes up the largest part of the diet.

Balancer – in theory, any feed or supplement that balances the horse’s forage diet but in practice, a term used to describe a concentrated feed, usually pelleted, fed in quantities of around 1g per kg bodyweight (500 g for a 500 kg horse), to balance forage.

Betacarotenes – nutrients found in plants, which are converted to vitamin A in the body. Sometimes called provitamin A. Unlike vitamin A, they are not toxic in very high quantities.

Bioflavonoids – a group of antioxidant compounds found in plants, which have anti-inflammatory effects and other health benefits. Found in citrus, soft and stone fruits, herbs including parsley, elderberries, rosemany and thyme, and dark green vegetables.

Biotin – one of the B-complex vitamins, necessary for healthy metabolism and cell growth and helpful to promote healthy hoof horn, skin and hair growth when fed in supraoptimal amounts.

Boswellia – the resin of a tree – also known as frankincense – which is used in herbalism for its therapeutic effects including anti-inflammatory properties.

Branched chain amino acids – the amino acids (building blocks of protein) leucine, valine and isoleucine, all of which are essential and which can be used directly for energy by skeletal muscle. Supplementation may be useful for hard working endurance horses or for horses with muscle challenges.

Calorie – a unit of energy, which is the amount of heat required to raise the temperature of 1 g of water by 1 degree centigrade. The joule (J) is used to describe the energy in horses feed in the UK (1 calorie = 4.184 J), and due to the large quantity of energy horses require, the term megajoule (MJ) is most often used. Sometimes the term calorie will be used in non-technical articles to help readers understand dietary energy.

Coarse mix – compound feed that looks like a muesli, usually consisting of flaked cereal grains, nuts and other ingredients that may include chaff, flaked soya, peas or beans, dried vegetables e.g. carrot and herbs e.g. mint. Formulated to balance typical forage when fed at the full recommended amount.

Cobalt – a micromineral involved in the synthesis of vitamin B12 (cobalamin) by gut micro-organisms, and in enzyme function. Deficiencies are unlikely because most UK forage and feeds contain adequate amounts.

Chasteberry – the fruit of the Agnes Castus shrub, which has been used since the 4th century BC as a female hormone balancer. Also used for horses and ponies with Cushing’s sydnrome.

Chondroitin – a glycosaminoglycan component of cartilage and connective tissue that, when orally supplemented, has been shown in research to promote joint health by counteracting cartilage inflammatory processes. Manufactured from fish or animal cartilage.

Compound feed – a manufactured feed that comprises of a more than two ingredients. Could be a concentrate feed or a chaff.

Concentrate feed – a feed higher in energy and protein per given weight (e.g. per kg) than the natural forage horses evolved to eat. Includes straight grains and blends, manufactured compound feeds and is sometimes used to describe moderately high energy fibre feeds such as sugar beet and quick dried chopped forages.

Copper – a micromineral that is essential for healthy connective tissue, skin and hair, for immune and nerve function and many enzymes processes. Must be supplemented in the diet because UK forage is naturally low and deficient for horses. Copper (Cu) is essential for the use of iron in the blood. It must be balanced with zinc (ideally at a 4:1 Zn to Cu ratio).

Cubes – compound feed that has been formed using a process forcing ground (often cooked) ingredients through the holes of a die. Versions formed by the same basic process are also – loosely depending on shape and size – called nuts, pellets and pencils. Formulated to balance forage when fed at the full recommended amount.

Dry matter – describes feed without its natural moisture content, which is present in all feeds. Most compound feeds and hay are about 88% dry matter (therefore 12% water), which means they contain about 880 g of dry matter and 120 g water per kilo.

Duodenum – the first part of the small intestine, which leaves the stomach. About 1 m long in the mature horse.

Electrolytes – compounds that dissolve into ions in solutes such as water. In the diet – the macrominerals involved in body fluid balance, including sodium, chloride, potassium and also magnesium and calcium. Electrolytes are lost in sweat and must be replaced in the diet. Horses in work cannot replenish enough sodium and chloride from normal diets so must have salts supplemented.

Enzymes – proteins that act as catalysts in chemical reactions. Animal bodies contain about 100,000 different enzymes. They control the rate at which chemical reactions in the body occur, and they also help body cells to communicate with each other.

Fibre – an essential macronutrient for horses, without enough of which they will suffer illness. Fibre is a group of carbohydrates that occur mainly as the cell wall of plants, giving them the rigidity to stand up, but also include various gums and gel-forming substances. Fibre cannot be digested by gut enzymes, and the horse relies on beneficial micro-organisms in the gut to release the nutrients it contains. Most horses should get most of their nutrients from fibre-rich feeds.

Flaxseed and flaxseed oil – Flax seeds are harvested for their high content of oil, which is the richest vegetarian source of health-promoting omega-3 fatty acids. The seed is also rich in protein, of a reasonable quality. High energy supplements, ideal for condition. Traditionally fed to horses for a bloom in the coat, and can reduce itchiness.

Fish oils – oil from the flesh of oily fish including salmon, tuna and mackerel, and from the livers of white fish e.g. cod. Fish oil is rich in the health-promoting omega-3 fatty acids (FA) eicosapentaenoic acid (EPA) and docosahexaenoic (DHA), as well as vitamins A and D. The fish don’t actually make these fatty acids, but instead accumulate them from the algae and plankton they eat. Increasing dietary omega-3 FA can have anti-inflammatory effects and a wide range of health benefits and are commonly supplemented for joint support.

Forage – a term that as used to describe all animal feed (also called fodder) but nowadays generally used to describe fibrous feed or roughages.

Fortified – fortified compound feeds contain the vitamins and minerals missing from the forage in a horse’s diet.

Ginger – a warming spice with anti-inflammatory properties, often found in joint-supporting supplements.

Ginseng – an ancient remedy sourced from a group of plants of the genus Panax. Considered ‘adaptogenic’, or balancing on the body, with different effects depending on the condition. Commonly supplemented for energy, reducing stress, concentration and improved sleep.

Glucosamine – a hexoamine sugar and a building block of the compounds that are constituents of joint cartilage. Sourced from shell fish carapaces, with vegetarian sources becoming more available. Commonly supplemented to horses, humans and dogs for joint support.

Green-lipped mussel extract – an extract from large New Zealand mussels, rich in omega-3 FA and supplemented for its anti-inflammatory effects. Used to support joints and respiratory health.

Haemoglobin – the oxygen carrying molecule found in the blood, in red blood cells.

Hindgut – the large intestine, which consists of the caecum and the large and small colon. The part where most microbial fermentation takes place in the horse, and where otherwise-indigestible fibre is broken down and useful nutrients, which the horse can absorb, are released.

Ileum – the final part of the small intestine, which leads into the caecum (the first part of the large intestine).

Iodine – a micromineral essential for producing thyroid hormone, which is involved in metabolic rate, oxygen consumption, growth and development. Most UK pasture is short in iodine for horses, and the richest feed source is seaweed.

Iron – a micromineral involved in oxygen uptake, transport and storage in the blood and muscles, and in enzymes. Most UK pasture supplies plenty for most horses, and over-supplementation can cause toxicity. Iron deficiency in horses is rare, and most anaemia is not linked to low dietary iron intake.

Isotonic – having the same osmotic pressure e.g. a solution that is isotonic to the blood has the same concentration. A rehydration solution should be isotonic to the blood to ensure it is taken up into the body.

Jejunum – the middle part of the small intestine, extending from the duodenum to the ileium.

Lecithin – a phospholipid also known as phosphatidylcholine, which is a source of choline and inositol. Supplemented for brain support and found in some calming products.

Legume – a family of plants which includes alfalfa, clover, soya beans, peas and field beans. Deeper rooted plants than grass, so contain more minerals. Usually fed in small quantities in the UK, often as quick-dried alfalfa chaff.

Macrominerals – essential minerals needed by the horse in grams per day rather than milligrams. Includes potassium, calcium, phosphorus, magnesium and sodium.

Macronutrients – essential nutrients needed in relatively large amounts daily, e.g. protein, carbohdyrates including fibre, and fats and oils.

Magnesium – a macromineral involved in bone structure, cell membrane structure, enzyme function, genetic material and energy metabolism.UK pasture usually supplies enough for most horses, but some seem to benefit from extra supplementation.

Maintenance – a term used to describe a horse’s requirements when not in work or reproducing.

Manganese – a micromineral involved in enzyme function and important for healthy joint tissue. UK pasture usually supplies enough but it is usually added to multi-spectrum supplements and compound feeds.

Methylsulphonylmethane (MSM) – commonly used in supplements, MSM is a biologically available source of sulphur, and a powerful antioxidant. Supplemented most often to support joint, hoof, hair and skin condition.

Micronutrients – nutrients needed in relatively small amounts per day, including vitamins and minerals.

Myoglobin – the oxygen carrying substance in the muscles, which contains an iron pigment called haem. In cases of tying up (rhabdomyolysis), myoglobin is released from damaged muscles cells and may be seen being passed in the urine.

Osmosis – the movement of solvent from an area of lower concentration to an area of higher concentration, through a semi-permeable membrane.

Peristalsis – the wave-like muscular movement of the gut wall, which propels partially digested food (digesta) through it.

pH – describes the acidity or alkalinity of a substance. pH7 is neutral, lower than 7 is acidic and higher than 7 is alkaline. The measurement is of the hydrogen ion concentration of a solution.

Phosphorus – an essential mineral that is the second most abundant element in the body. Most is involved in structural roles, and 85% is found in the bones and teeth. Phosphorus (P) is also a constituent of genetic material and cell membranes and is involved in energy production. An excess causes calcium (Ca) deficiency, and the unbalanced P to Ca levels in cereal grains and their by-products must be carefully balanced.

Potassium – an essential electrolyte mineral, most of which is found inside the body cells. It plays an important role maintaining pH (acid/alkali) and electrolyte balance, influences muscle (skeletal, gut and heart) contraction and affects nerve function. Potassium is controlled within a narrow range by the body and excesses are easily excreted. UK pasture supplies plenty but shortages may occur from losses in prolonged, excessive sweating.

Prebiotics – a specific type of carbohydrate used in animal feed to boost the beneficial micro-organisms in the gut. Prebiotics are not digested by the animal’s own digestive enzymes, and so are available as a food source for the beneficial bacteria.

Probiotics – live feed additives that promote the beneficial micro-organisms in the gut, and usually used to describe live yeast or bacteria. Live yeast products are thought to create a more favourable environment for the beneficial bacteria in the gut.

Protein – an essential macronutrient made up of amino acids, which have a wide variety of roles in the body including structural, enzymes, hormones, immune compounds and transport compounds. Protein is not used to any great extent for energy in the healthy horse. Protein makes up about 17-19% of the body.

Protein quality – describes the amount of essential amino acids a protein contains. A higher-quality protein contains higher amounts of essential amino acids.

Pro-oxidant – a substance that has a promoting effect on oxidative processed in the body (opposite to an antioxidant). Too much oxidation results in oxidative stress, which is harmful to the body and is believed to be involved in many disease processes. Antioxidants may help to reduce the harmful effects of oxidative stress.

Psyllium – the husks of a type of plantain, which is a rich source of fibre including soluble mucilage. Fed to help clear sand out of the gut and to sooth irritated or inflamed gut cells; used in colitis. May also help stabilised blood glucose.

Ration – the total amount of feed a horse ingests per day.

Roughage – describes fibrous feeds, usually long-fibre feeds such as hay, haylage and straw; also called forages.

Rosehips – the fruit of the rose (Rosa spp) bush, and a rich source of vitamins and antioxidants. Supplemented in horse diets to help promote healthy hooves, and mobile joints.

Selenium – a micromineral that acts as an antioxidant in the body. Most UK forage is short of selenium so it always needs to be supplemented.

Silicon – a micromineral not classed as essential for horses, but plays a role in cartilage and bone metabolism. Horses are thought to obtain enough from any diet due to its frequency in plants and the environment, but some supplements may include it as an ingredient.

Sodium – an essential electrolyte mineral, 30% of which is found on the bone surfaces, the rest of which is found outside body cells in the extracellular fluid. It plays an important role maintaining pH (acid/alkali) and electrolyte balance, as well as being involved in nerve and muscle function. Sodium is controlled within a narrow range by the body and excesses are easily excreted. Requirements depend on workload because sodium is lost in sweat. Most horse diets – especially working – are short in sodium without supplementation.

Straights – single feeds, such as grains (oats, barley, wheat, rye), and grain by-products (bran) but sometimes used to describe sugar beet as well.

Supplement – describes extra feeds that are added in small quantities to the daily diet e.g. vitamins and minerals, probiotics, nutraceuticals such as glucosamine, and herbs. Manufactured supplements that are made from a blend of ingredients are classed as complementary feedingstuffs.

Sward – a description of the mat of grass on turf.

Tincture – an extraction of the active component of a herb, usually with alcohol but sometimes with vinegar such as cider apple vinegar. Tinctures provide a stable and well-preserved way of administering herbs.

Turmeric (and curcumin) – turmeric is a warming spice that is related to ginger. It is rich in the pigment curcumin, which has powerful health-promoting properties that have been the focus of much research.

Vitamins (A, B complex, C, D, E and K) – essential micronutrients that are involved in a variety of body processes; usually split into water-soluble (C and B-complex) and fat-soluble (A, D, E and K). Water-soluble are not retained by the body and are excreted if too much is ingested (with the exception of vitamin B12). Fat-soluble are absorbed in association with dietary fat and rely on adequate bile function. Grass is a rich source of most vitamins but losses occur in drying to hay an haylage should be supplemented.

Yeast – both live and deactivated yeasts are commonly added to horse diets.

Zinc – a micromineral involved in a wide variety of body functions, including enzyme function, hormones, immune function, skin health and wound healing, genetic material, cell and tissue growth and protein synthesis. UK pasture is usually short for horses so zinc must be supplemented. Zinc (Zn) must be balanced with copper, ideally in a 4:1 ratio (4 parts Zn to 1 part Cu)

About Clare MacLeod

Clare MacLeod MSc RNutr is one of the UK’s few registered independent equine nutritionists who also has expertise in health and fitness. She advises private and commercial clients in all sectors of the horse world and is a hands-on horse owner herself. Clare is passionate about correct nutrition as a foundation for good health, without which peak fitness is not possible. She states “Good nutrition isn’t everything, but there’s nothing without it”.