Simple hard feeds

Characteristics of the main concentrated feeds

Like other herbivores, the horse’s digestive tract is optimised for microbial digestion of forage in the large intestine. Concentrated feeds which are incorporated into the ration are for the main part digested by the enzymes in the small intestine, located before the large intestine in the digestive tract.

Concentrates, and especially cereals which are mainly composed of starch, represent a high source of energy. However, their protein, mineral and trace-element contents are variable, often needing mixing with other feeds to balance the daily ration, according tp the type of forage fed. For example, legumes (grain or dehydrated forage) can be associated to brans to balance the Ca/P ratio.

avoine germée — Germinated oats © L. Le Masne

orge aplatie — Crushed barley © L. Le Masne

maïs floconné — Maize flakes © L. Le Masne

In addition, a mineral and vitamin supplement (MVS) should be incorporated, if there is a mineral and vitamin deficiency in the feed, with regard to the animal’s needs.

Composition of the main simple concentrates
Simple hard feeds		Energy in UFC*/gross kg of feed	Protein in MADC*/ gross kg of feed	Calcium (Ca) and Phosphorous (P)	Characterisitic nutrients, vitamins and trace-elements	Balance of the ration
Cereal grain (barley, oats, maize, wheat, rice, rye, triticale)		0,87 to 1,16 UFC • high energy content • High starch content (except oats) • low cellulose content (except oats)	55 to 102 g MADC • Low digestible protein content • Low essential amino acids content (EAA)	• well endowed with P (Phytic P not absorbed during digestion) • poor in Ca	• well endowed with vitamin B • Poor in vitamin s A and D	Need to supplement in protein, Ca and P (to a lesser extent) and MVS
Cereal by products (brans= husks of wheat or corn from flour mills, remilled rice ofr rice flour)		0,77 to 1,10 UFC • Less energycontent • High cellulose content • Lower strach content	106 -116 g MADC High Nitrogen content	• Well endowed in P • Poor in Ca	Well endowed in Mg (except maize)	Do not use for more than 30 % of the ration, otherwise the Ca/P imbalance is increased
Dehydrated forage	Sugar beet	0,76 UFC • Rich in highly digestible fibers • Poor in starch and soluble sugars	26 g MADC	• Very rich in Ca • Poor in P	-	Should be balanced with cereal or bran to increase the P content of the ration
Dehydrated forage	Dehydrated alfalfa	0,57 to 0,70 UFC • Fiber rich • no starch	86 to 146 g MADC • Rich in essential amino acids • rich in lysine	Very rich in Ca	-
Legume / protein oil plant seeds (field beans, lupin, peas, broad beans)		0,92 to 0,96 UFC High energy content	161 to 257g MADC • Very high protein content • Well balanced in Essential amino acids	• well endowed in Ca and P (lupin, linseed) • poor in Ca (field beans)	• Low in sulphur AA • Lupin very rich in manganese (Mn)	Should be given to supplement cereal as the ratio MADC to UFC is very high, leading to an excess of nitrogen (protein) in the ration if too much is fed (over sollicits the liver and kidneys)
By products from oil plants (soya , linseed, groundnut, sunflower, rapeseed, copra, palm kernel meal)		0,52 to 0,91 UFC • Rich in energy • No starch in meals	119 à 413 g MADC • High protein content • Well balanced essential amino acid content	Well endowed in Ca and P	Poor in sulphur AAI
Vegetable oils (rapeseed, maize, soya)		2,96 UFC Very high energy content	Does not supply any protein	Does not supply any minerals	Rapeseed, sunflower and soya oils very rich in essential fatty acids (EFA : omega 3 and 6)	Very digestible when entering between 10 % to 15 % of the ration

* UFC = Unité fourragère cheval (horse forage unit), represents the energetic worth of a feed

* MADC = Matières azotées digestible cheval (digestible proteins), represents the protein worth of a feed

Feed values of some cereals, legumes and oils

According to INRA charts, 2010
	Oats	Barley	Maize in grains	Wheat bran	Field beans	Soya meal (48)	Oil
Dry matter DM (%)	88,1	86,7	86,4	86,6	86,1	87,6	100
Gross cellulose (%)	12,8	4,6	2,2	9,2	87	68	0
UFC (g/ gross kg)	0,87	0,99	1,12	0,77	0,95	0,83	2,96
MADC (g/gross kg)	69	71	57	112	209	383	0
Ca (g/kg of DM)	1,1	0,7	0,4	1,4	1,7	3,9	0
P (g/kg of DM)	3,2	3,4	2,6	9,9	5,5	7,1	0

Mode and order in which to feed

Dividing up the ration

Correctly feeding one’s horse, requires that cereals be given in portions throughout the day to avoid creating any disorders in the large intestine. Mixing the different cereals with forage distribution in the daily ration helps to balance the nutritional elements. A ration should contain at least 15% of raw cellulose to ensure good digestive hygiene.

Order

It is best to favour giving forage before concentrates. This prevents the sweeping of the concentrates by the forage towards the large intestine. Digestion of concentrates should primarily take place in the small intestine.

When should one give concentrates with regard to exercise ?

It is better to give a meal of concentrates at least two hours before exercise, this can even be extended to 4 to 6 hours before an important competition (racing, endurance racing, eventing). Indeed, exercise causes a decrease in the volume of blood due to a movement of fluids towards the digestive tract, thus compromising the operation of the heart and heat regulation.

During intense exercise, supplying sugar and starch in the ration just before work, causes a burst of insulin (2 hours later) which then stops the horse from mobilising the muscle glycogen, and fat reserves required to feed the muscles during efort. This leads to premature tiredness during intense effort.

However, fasting before exercise is not good either, as it can predispose to, ulcers (increase in acidity in the stomach). Some studies also show that stereotypical behaviour (cribbing, windsucking) can be linked to ulcers.

Therefore, small quantities of forage (1-2kg, or more) given 1-3h before exercise can be beneficial. This will have minimal effect on the availability of substrates and oxidation during sustained effort.

After the competition, hay can be given ad lib, and a high starch content feed given 2 to 4 hours after, not going above 0,3 % of the horse’s body weight.

It is imperative to regularly weigh (e.g. at each new delivery) the measure used to distribute the feed. Moreover, do not substitute one cereal for another at equal volumes. For example a liter of oats has two times less energy content than a liter of maize.

Preparing the feed

Any cereal can be given whole. However for the harder grain (maize, barley, wheat), it is better to crush or roll , particularly for older horses. Digestibility in the small intestine (enzyme digestion) is better when the grain is transformed (crushing, rolling, soaking, cooking….).

Mixing chopped fibers with concentrates

Adding chopped fibers in the ration of concentrates slows down ingestion, and increases saliva production, improving the buffer role of the stomach, this limits the risk of blockage of the oesophagus in greedy horses, and other digestive diorders (colic, ulcers….).

Excess of starch and glycemic index of a ration

When high quantities of cereals are given per meal, part of the starch which is not digested in the small intestine, transits towards the large intestine where it will ferment. This fermentation process will lead to metabolic disorders due to acidification, and will cause colic and laminitis. In the long term it can also lead to reducing sensitivity to insulin (regulating glycemia in the body), the animal then becomes insulin-resistant, which is one of the characteristics of horses suffering from equine metabolic syndrome. Excess of energy content in a foal’s ration can also be a factor contributing to the development of osteoarticular disorders such as osteochondrosis.

The glycemic index represents the amount of glucose released following the digestion of feeds which will lead to high glycemia (amount of sugar in the blood) and a burst of insulin at mealtimes. The role of insulin is to maintain a balance in blood sugar levels, by having it used following digestion, by the body tissues (muscles, fatty tissues…) and to decrease the production by the liver.

The feed for horses with high energy requirements (top level competition horses) lead to an increase in the part of soluble sugars, which are digested quickly in the small intestine (in the form of cereals, starch), to the detriment of carbohydrates present in foage and mainly digested by th large intestine. As a result, diets with a high soluble sugar content, have a high glycemeic index.
The glycemic index is variable depending on the feed and on the individual.

L'index glycémique est variable selon les aliments.

Variability of the glycemic index according to the type of feed and animal (according to Cerdan 2012)
	Low glycemic index	High glycemic index
Type of feed	• Hay • Feeds with a high fiber content (rice bran, wheat bran, sugar beet, soya bean pods) • Oils	• Cereals : oats > Maize > Barley • Crushed cereals > whole cereals • Thermomechanically processed cereals (flaked, extruded, pelleted, cooked) > unprocessed cereals

The glycemic index also varies according to the physiological state of the horses. The glycemic response for the same food will be higher for foals, mares at the end of gestation, obese or sedentary horses.

Glycemic response according to the physiological state of horses (from Cerdan, 2012)
	Low glycemic index	High glycemic index
Comparison of the glycemic response between two different physiological states for the same food	Adult	Young foal
	Normal adult	Obese horse
	Lactating mare	Gestating mare
	Horse in training	Sedentary horse

A low glycemic index ration should be favoured.

Carbohydrates represent the greatest source of energy to cover the requirements of a horse in intense work. A high glycemic index ration will therefore be favored for exercise of short duration and high intensity. A low glycemic ration will be more suited to endurance work.
However, incorporating oils (to supplement or to replace cereals) is a very good way to increase the energy levels without the drawbacks of high starch content feeds. Oil can be used for horses subject to endurance work.

Maximum quantities of cereal to be given per meal and per day for a 500 kg horse

To respect the maximum intake of:

1g of starch/kg of body weight/meal
2g of starch/kg of body weight/day

Aliment	Starch content (in g/gross kg) (INRA, 2011)	Maximum quantity to be given per meal (in gross kg of food)	Maximum quantity to be given per day (in gross kg of food)
Oats	362	1,4	2,7
Barley	521	0,96	1,9
Maize	641	0,78	1,56
Rice	758	0,66	1,31

Calculation details for the barley example: The starch concentration of barley is 602 g/kg DM (with 86.7% DM), or 602 x 0.867 = 521 g/kg gross. For a 500 kg horse, the quantity of starch must not exceed 1 g of starch/kg of live weight/meal, ie 500 g or 0.5 kg of starch per meal. Barley contains 521 g of starch/gross kg, i.e. 0.521 kg of starch/gross kg, so to respect 0.5 kg of starch, you will need 0.5 / 0.521 = 0.96 kg gross maximum of barley per meal.

To avoid any starch excess, it is advisable not to exceed the equivalent of 2 kg of barley/day, which corresponds to approximately 6L of crushed barley.

Ce qu'il faut retenir

• Feeding hay in the daily ration is essential.
• Feed concentrates to the horses who really need it.
• Be mindful of excess starch ! it is advisable not to exceed the following :
     ► 1g of starch/kg of body weight/meal
     ► 2g of starch/kg of body weight/day
    • Avoid too much volume per meal, fraction the ration into small portions.
    • Balance the Ca/P ratio.