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CASE NOTES


Full hand feeding of horses — Suggested rations for horses during droughts

Dr Petrea Wait BSc BVMS (Hons.), District Veterinarian, South East Local Land Services

Introduction

Supplementary feeding, or as is often the case in drought the full hand feeding of horses, is expensive and time-consuming. During droughts feed becomes difficult to source and more costly, and often decisions need to be made about whether to keep horses and feed them or to sell. You may be tempted to do nothing in the hope that a poor season will not turn into a drought. But remember, before you take that option, it is your legal responsibility to ensure that horses do not starve to death or become distressed during a drought.

Ideally horses should be maintained in Body Condition Score of 2 out of 5 or better during a drought to ensure they maintain good health. Horses in poor body condition are more at risk of illness due to a reduced immunity, or injury as they search for food or become weak. Some horses, particularly pregnant and lactating mares, and growing young stock may need their feed increased to meet their needs. Horses should be weighed or condition scored regularly to ensure that feed is adequate and horses are not being overfed or underfed. More information on the condition scoring of horses is available in the DPI Primefact 928 'Estimating a horses condition and weight' at www.dpi.nsw.gov.au .

Information about welfare scoring of horses in poor body condition is available in the DPI publication 'Welfare scoring nutritionally deprived beef cattle, dairy cattle and their crosses, sheep and horses, at www.dpi.nsw.gov.au .

The tables located at the end of this article should be used as a guide to help you develop a suitable diet for your horse when no or limited pasture is available. Remember that every horse is an individual with a different metabolism, and that your horse may require more or less feed than recommended.

Image of horse condition score 2
Figure 1: Horse in Body Condition Score 2. Horses should not fall below this weight

Digestive function in horses

Horses have a unique digestive tract which has adapted to a lifestyle in which they graze almost continuously. Their single stomach is small in size and secretes digestive acids constantly to initiate the digestive process. If there is no food in the stomach then this acid damages the stomach lining leading to ulceration.

Horses also secrete bile constantly from the liver into the small intestine as they do not have a gall bladder to store it in. Bile is responsible, along with other pancreatic enzymes, for the breakdown of fats in the food. Up to 60% of carbohydrate digestion and almost all protein digestion occurs in the small intestine, so the slower the feed moves through this region the more time the digestive tract has to absorb these nutrients. Horses also absorb toxins very readily through the small intestine making them far more susceptible to colic or death than ruminant animals which rely on microbial detoxification in their rumens. Moulds, bacterial toxins such as botulism, high levels of substances such as Nitrates, Prussic acid and urea, and poisonous plants are all particularly dangerous to horses and may be present in feeds that appear to be safe for cattle and sheep.

The hind gut, comprising the large fermentation vats of the caecum and large intestine, is responsible for the breakdown of plant fibres and remaining carbohydrates by microbes into volatile fatty acids which are absorbed through the gut wall. Microbes in the caecum are quite specific to the type of feed they digest and can take 2 – 3 weeks to adjust to a new diet and return to normal digestive function. The caecum is a large sac with a single opening and without sufficient fluid can become impacted with dry food materials. The large colon, where fibre digestion is completed, has a segmented or 'sacculated' structure which is also prone to trapping dry ingesta or twisting under the influence of trapped fermentation gasses resulting in colic.

It is very important that horse owners try to simulate the natural grazing behaviour of horses to prevent digestive upsets. This becomes very difficult when horses are kept in drought conditions where pasture is absent or very limited. The old adage of feeding 'little and often' is never more relevant. At least 50% of the diet of a horse should comprise of roughage, ideally in the form of hay, chaff or silage. To slow consumption this can be provided in slow feeder hay nets for almost ad lib consumption, or placed out 2 – 3 times daily. The practice of placing large round or square bales out in the paddock can be wasteful and expensive as horses tend to pick through the bale and soil the remainder. They may also consume more than they need, and greedy dominant horses may prevent shy feeders from getting their portion.

Image of horse feed pellets and chaff
Image of horse feed pellets and hay
Figures 2 & 3: If concentrates are fed as part of the ration they should be split into two or more meals and diluted with roughage. The pellets are mixed into chaff (top) and spread out over hay (bottom).

The concentrate portion of the ration should also be broken up into at least two feeds per day and ideally diluted with an equal volume of chaff to slow digestion and buffer acid production. Any changes in diet need to be undertaken gradually with the old feed gradually reduced while the new one is proportionally increased over 10 – 14 days. Horses should also have free access to clean water at all times to aid in the passage of ingesta through the gut and prevent dehydration.

Energy

Energy is the most important nutrient for the horse. A horse burns energy every minute of every day just to maintain basic life functions. The more a horse exerts itself, be that through exercise, producing milk for a foal or just growing, the more energy it consumes. This energy needs to be replaced through the diet, and different feeds have different levels of energy. The amount of energy in a feed is expressed as Digestible or Metabolisable Energy (DE or ME) and is measured in megajoules (MJ). Roughage feeds such as hay and chaff generally have low levels of energy while concentrated feeds like grains and oils have higher levels of energy.

A list of average ME's for common horse feeds is attached at the end of this article. Most prepared horse feeds provide the nutritional information on the bag or on the company website. Feed testing to determine exactly what is in the feed you are using is also available through the DPI Feed Quality Service at www.dpi.nsw.gov.au .

Image of horse feed lucerne hay and rye hay
Figure 4: Roughages such as Lucerne hay (left) or rye hay (right) are good options for horse diets

Rations should be formulated to meet a horse's energy needs first. Initially, a roughage source should be selected that is available and of the best quality (highest ME) that you can afford. Using the tables at the end of this article, check how much of this feed type will be needed to meet your horse's energy needs. If this feed alone cannot meet your horse's needs, or is too expensive, you can add to, or supplement, part of the ration with a concentrate feed such as grain or pellets.

The addition of vegetable oil to horse diets is an economical way to increase energy intake. Up to 100ml per 100kg body weight can be fed, but this must be introduced slowly, split into at least two feeds per day, and most horses find more than 250ml per feed unpalatable. Also, the addition of large volumes of oil may hamper the uptake of essential nutrients including vitamins, minerals and amino acids which may result in deficiencies and abnormal growth in young horses. A ration balancing supplement may be required which increases the cost of feeding.

Protein

Protein is also an essential nutrient in horse diets. Fortunately, most feeds produced for horses in Australia meet the needs of adult horses at rest without the need for additional expensive supplements. Only young, growing horses, pregnant mares and horses in intense work will need more protein than a diet based on cereal hay and grains or Lucerne will provide.

The diets suggested in the tables at the end of this article are balanced for both energy and protein, unless stated. If additional protein is required, good sources are Lucerne, lupins (must be crushed or soaked), or soy or linseed meal.

Vitamins and Minerals

Diets based on cereal hay and grain alone are likely to be deficient in calcium, and have a calcium:phosphorous imbalance, particularly in growing horses. This could be overcome by feeding Lucerne hay in place of the grass hay, or exchanging the grain for a pellet formulated for breeding horses, or the addition of ground limestone to the ration at 60g/day for growing and adult horses, and 90g/day for pregnant or lactating horses.

Hay and grain based diets are also low in salt so this may need to be added at a rate of 0.5%, or 5g per 1kg of grain fed. Salt could be provided in a loose lick or a block, but not all animals will get a sufficient intake. Of course if the water supply has a high level of salt or a complete mix or pelleted feed is provided no additional salt will be needed.

Vitamins A and E may also become deficient if horses do not have access to green pasture for more than 3 – 6 months, although only a very small amount of pasture will supply adequate amounts. Recently baled quality hay and yellow maize will contain Vitamin A, and grains and hay may have Vitamin E.

Selenium may also be lacking in the diet if the hay and grain supplied comes from an area with soils deficient in this mineral. Seek veterinary advice if you suspect deficiencies, a blood test may be needed to confirm this, as well as for information about supplementation.

Caution when feeding some hays to horses

A number of grass hays contain high oxalate levels which bind dietary calcium making it unavailable to the animal. These include Setaria, Buffel and Kikuyu grasses which have an oxalate level of greater than 1%, Pangola and Green Panic with almost 1%, as well as Rhodes and Teff grasses which near 0.5%. Diets with greater than 0.5% oxalate content are at risk of causing Nutritional Secondary Hyperparathyroidism or 'Big Head' disease. Avoiding hays with a high oxalate level is advised, or minimising their use and supplementing with at least 2kg of Lucerne hay which contains a horse's daily requirement for calcium. Alternatively additional calcium will need to be provided, ideally in a chelated form, particularly to growing and breeding horses. There are a number of calcium containing supplements commercially available specifically formulated to prevent the disease on high oxalate diets.

Sorghum hays often contain some levels of Prussic acid which may induce a cystitis-ataxia syndrome in horses. Sorghum (sudangrass, johnsongrass), millet (Japanese, German, Foxtail) and canola hays can also contain high levels of Nitrates, particularly if baled when drought or frost stressed. Horses are less susceptible to nitrate poisoning than cattle and sheep but levels above 2% (20,000ppm) could result in toxicity in horses.

Some varieties of vetch are associated with illness in horses. Hairy vetch (Woolly pod or popany) has been responsible for causing systemic granulomatous disease in horses, as well as containing cyanogenic glycoside compounds in the seeds which may result in sudden death or neurological disease. Crown vetch is rarely seen in Australia but is also toxic to horses causing respiratory and cardiac failure. Other vetch varieties can be fed as hay, although there have been reports of colic associated with its feeding and it is recommended to limit the amount fed to 50% of the diet.

Image of woolly pod vetch plant
Figure 5: Hay made from woolly pod vetch varieties can cause serious illness in horses and should be avoided

Feeding silage or haylage

Silage and haylage may also be fed to horses and can be a valuable feed if of good quality and free of mould and contaminants. It is important to remember that silage and haylage have a higher water content than hay, silage contains less than 60% dry matter and haylage contains between 60 – 85% dry matter, while hay is commonly 90% dry matter, thus a larger quantity needs to be fed to provide the same nutritive value as hay.

Changing or introducing new feeds

New feeds, especially grains and pellets, must be introduced into the ration gradually to prevent illness such as colic and laminitis. Even changing from one type of feed to another, i.e. from oats to barley, will require the gradual reduction of one feed type with a concurrent increase in the second feed type over 10 to 14 days.

Horses with special dietary needs

Some horses, especially of pony breeds (although horses of any breed may be affected), are sensitive to diets high in plant sugars known as non-structural carbohydrates (NSC). Cereal hay and grain, grain based pelleted feeds, sugarcane hay, as well as hay made from improved pasture species such as clover and rye can be high in NSC. Feeding large volumes of these feeds may induce illnesses in these horses such as Equine Metabolic Syndrome (EMS), Pars Pituitary Intermedia Disease (PPID), Insulin Resistance (IR) and Laminitis (founder). More information about these diseases is available at thehorse.com.

Low sugar hays such as Lucerne, Teff, Microlena or Rhodes grass should be fed in preference to these horses, if available. Alternatively, high sugar hays can be soaked in water for 30 minutes prior to feeding to reduce the sugar content (discard the water). Beet pulp and copra based feeds manufactured for horses could also be used to replace some of the roughage portion of the diet.

If concentrate feeds need to be included in the ration to increase the energy density for growing, breeding or working horses, or because sufficient roughage is not available, consider the addition of oil to the diet, as mentioned above, or the use of a pelleted ration specifically designed for horses with metabolic related disorders.

Horses with Polysaccharide Storage Myopathy (PSSM) will also benefit from a diet low in NSCs. PSSM is a disease most commonly seen in Quarter Horses and their crosses including Paints and Appaloosas, as well as Warmbloods and Draft breeds. It causes symptoms similar to 'tying-up' such as muscle pain, reluctance to move and sweating, but also muscle tremors and even severe colic. More information about PSSM is available at ker.com .

It may also be difficult to maintain the weight of older horses as their metabolic and digestive efficiency reduces with age. There is no defined age at which a horse becomes a 'senior' but any horse of mature years that is losing weight on its normal feeding regime, showing signs of muscle loss from the back and rump, developing a swayback, or has poor hoof and coat condition can be considered nutritionally aged.

These horses often require more highly digestible sources of energy and a higher protein content in their ration. There are several pelleted feeds designed for older horses to meet these needs or the use of a pellet designed for mares and foals can be suitable. Alternatively, ensuring good quality Lucerne hay and adding oil to the diet should help address their needs.

Image of horse in good condition
Figure 6: Aged horses may require additional care if they are not maintaining condition, being old is not an excuse for a horse being in poor condition. The horse below is a 23 year old Thoroughbred who has lost muscle condition on his topline but maintains good weight and health with the addition of pellets designed for broodmares.

Of course if any horse, aged or not, fails to gain weight on what you believe is an adequate diet veterinary advice should be sought particularly with regard to dental care, worming and possibly a blood test to assess for any underlying disease.

Notes when using the feeding tables

The feeding tables below are designed to simplify preparing rations suitable for a range of different horses. They are formulated based on a single roughage type for horses that have low energy requirements, or a single roughage plus a single concentrate feed type for horses with higher energy requirements. Often during a drought it becomes more cost effective to feed a higher proportion of concentrate as hay prices increase, so the hay plus concentrate rations are designed to safely accommodate this whilst ensuring the ration provides sufficient energy.

To use the table, select the type of horse you are feeding from the column on the left. The table is split into two sections, one for growing horses and one for adult horses. Then, select the type of feed/s you have available from the top row. You will need to know the Metabolisable Energy (ME) of the feed you are using – if you do not have a feed test result or the feed does not come in a bag that provides this information, you can refer to Table 2 which lists feeds commonly available to horses with an average ME for that feed type. For example, if you are feeding Lucerne hay and oats to a 2 year old horse which will have a mature weight of 500kg:

Image of two horses in different condtion
Figure 7: Every horse is an individual and may respond differently to the same diet. These Thoroughbreds of similar age and size are receiving the same ration, and although both are in good condition, the mare on the right is in much better condition compared with the mare on the left.

Figures in red indicate that the diet is not suitable for this class of horse as the animal cannot physically consume enough of the feed to meet its nutritional requirements for energy. This is particularly the case for growing young horses and mares in peak lactation where hay alone will not meet the animal's needs.

The figures in purple indicate that this diet will almost meet the weanling's requirements for energy. Oil could be added to the diet to make up for this deficit. It would be best to avoid the early weaning of foals and to only wean if very high quality hay and grain or pellets is available.

Figures in blue indicate that at peak lactation a diet based on grass hay and grain alone will be mildly deficient in protein. This could be overcome by the supplementation of grass hay with Lucerne or clover hay, or supplementation of 25% of the grain with crushed or soaked lupins, or a pellet formulated for breeding horses.

All figures in black indicate that the diet will provide sufficient energy and protein for that class of horse.

Feed quantities provided below are 'as fed' assuming that all feedstuffs listed are 90% dry matter.

More information

For more information on how to manage livestock during a drought, including drought planning, farm and pasture management, download the NSW Managing Drought Guide at: www.dpi.nsw.gov.au .

For more detailed descriptions of welfare scores, see the NSW DPI's manual, found here: www.dpi.nsw.gov.au .

Visit animalwelfarestandards.net.au for standards and guidelines for land transport of livestock and horses.

References

  1. Feeding Horses with Equine Metabolic Syndrome, Jan 2019. Hygain article viewed 26th Nov 2019 at www.hygain.com.au
  2. Feeding oil to horses: Choose wisely, Mar 2016. Equinews, Kentucky Equine Research, article viewed on 27th Nov 2019 at ker.com
  3. Feeding the Senior Horse, Apr 2019. Hygain article viewed 26th Nov 2019 at www.hygain.com.au
  4. Guide to Poisonous Plants, 2019. James L. Voss Veterinary Teaching Hospital, Colorado State University, viewed on 27th Nov 2019 at csuvth.colostate.edu
  5. Guide to Poisonous Plants, 2019. James L. Voss Veterinary Teaching Hospital, Colorado State University, viewed on 27th Nov 2019 at csuvth.colostate.edu
  6. Huntington, P. 2012. Alternative hays for horses, Equinews, Kentucky Equine Research, article viewed on 27th Nov 2019 at ker.com
  7. Larson, E. Mar 2019. Identifying and Managing Equine Metabolic Syndrome (EMS), The Horse Media Group, viewed 26th Nov 2019 at thehorse.com
  8. Managing and preparing for drought, 2018. Department of Primary Industries, viewed 18th Nov 2019 at www.dpi.nsw.gov.au
  9. Muller, CE. Sept 2018. Silage and haylage for horses, Wiley Online Library, viewed 18th Nov 2019 at onlinelibrary.wiley.com
  10. Nutrient Requirements of horses, 2007. National Research Council, Washington, viewed 25th Nov 2019 at nrc88.nas.edu
  11. Nash, D. 1999. Drought Feeding & Management For Horses, Rural Industries Research and Development Corporation, Kingston , ACT, viewed 21 Nov 2019 at agriculture.vic.gov.au
  12. The horse's digestive system, 30th April, 2019. Hygain, article, viewed 27 Nov 2019 at www.hygain.com.au
  13. Update: PSSM in Horses, Sept 2011. Equinews, Kentucky Equine Research, article viewed on 27 Nov 2019 at ker.com
  14. Waldridge, B. Jan 2010. Nitrate and Nitrite Toxicity in Horses. Equinews, Kentucky Equine Research, viewed 27th Nov 2019 at ker.com

© State of New South Wales through Local Land Services 2021. The information contained in this publication is based on knowledge and understanding at the time of writing December 2021. However, because of advances in knowledge, users are reminded of the need to ensure that the information upon which they rely is up to date and to check the currency of the information with the appropriate officer of Local Land Services or the user's independent adviser. For updates go to www.lls.nsw.gov.au .

Table 1. Suggested rations for horses of different weights, ages and physiological status utilising feeds of different energy values. ( pdf version )

Type of horse: Growing Mature weight (kg) (Est. actual weight) Required Digestible energy (DE) (MJ) Required Crude protein (g) Maximum Consumption kg/day (at 3% of body weight) Low Quality Grass Hay (kg/day) ME 6.0 MJ/kg Medium Quality Cereal/Grass Hay (kg/day) ME 7.0 MJ/kg Lucerne/ Clover / Ryegrass/ Phalaris Hay Only (kg/day) ME 8.5 MJ/kg 50% Hay (8.5 ME) + 50% grain/pellets (13ME) (kg/day) 50% Hay (10 ME) + 50% grain/pellets (14.5ME) (kg/day)
Weanling
(4 months)
400 (135)
500 (170)
600 (200)
56.5
60.2
69.0
675
720
825
4.1
5.1
6.0
10.3
11.0
12.7
8.8
9.5
10.8
7.3
7.8
8.9
3.7 + 2.4
3.9 + 2.5
4.5 + 2.9
3.1 + 2.1
3.3 + 2.3
3.8 + 2.6
Weanling
(6 months, moderate growth)
400 (175)
500 (220)
600 (260)
54.0
62.8
71.1
643
750
850
5.3
6.6
7.8
9.9
11.6
13.1
8.5
9.9
11.0
7.0
8.1
9.2
3.5 + 2.3
4.1 + 2.7

4.6 + 3.0
3.0 + 2.0
3.5 + 2.4
3.9 +2.7
Yearling
(12 months, moderate growth)
400 (260)
500 (320)
600 (385)
65.3
71.9
95.0
700
851
1023
7.8
9.6
11.6
12.0
13.2
17.4
10.2
11.3
15.0
8.5
9.4
12.3
4.2 + 2.8
4.7 + 3.0
6.1 + 4.0
3.6 + 2.5
4.0 + 2.7
5.2 + 3.6
18 months old 400 (310)
500 (390)
600 (465)
66.5
82.8
100.00
716
893
1077
9.3
11.7
14.0
12.2
15.2
18.4
10.5
13.0
15.6
8.6
10.7
13.0
4.3 + 2.8
5.4 + 3.5
6.5 + 4.2
3.7 + 2.5
4.6 + 3.1
5.5 + 3.6
2 years old 400 (345)
500 (430)
600 (515)
64.0
78.7
98.3
650
800
998
10.4
12.9
15.5
11.8
14.4
18.0
10.0
12.3
15.4
8.3
10.3
12.8
4.1 + 2.7
5.1 + 3.3
6.4 + 4.2
3.5 + 2.4
4.3 + 3.0
5.4 + 3.7
Type of horse: Adult Mature weight (kg) Required Digestible energy (DE) (MJ) Required Crude protein (g) Maximum Consumption kg/day (at 3% of body weight) Low quality Grass Hay (kg/day) ME 6.0 MJ/kg Medium Quality Grass/Cereal Hay (kg/day) ME 7.0 MJ/kg Lucerne/ Clover / Ryegrass/ Phalaris Hay Only (kg/day) ME 8.5 MJ/kg 75% Hay (7.0 ME) + 25% grain/pellets (10ME) (kg/day) 75% Hay (9.0 ME) + 25% grain/pellets (13ME) (kg/day)
Maintenance 400
500
600
56.1
68.6
81.2
563
656
766
12.0
15.0
18.0
10.3
12.5
14.9
8.8
10.8
12.8
8.5
8.8
10.5
6.6 + 1.5
8.1 + 1.9
9.6 + 2.2
5.1 + 1.2
6.3 + 1.4
7.4 + 1.8
Pregnant
(9 months)
400
500
600
62.3
76.1
90.0
654
801
947
12.0
15.0
18.0
11.4
14.0
15.2
9.8
12.0
14.2
8.0
9.9
11.7
7.4 + 1.8
8.9 + 2.1
10.1 + 2.5
5.7 + 1.3
7.0 + 1.7
8.3 + 1.9
Pregnant
(11 months)
400
500
600
67.4
82.4
97.5
708
866
1024
12.0
15.0
18.0
12.3
15.1

17.9
10.6
13.0
15.3
8.7
10.7
12.7
7.9 + 1.9
9.7 + 2.3
11.4 + 2.6
6.2 + 1.4
7.6 + 1.8
8.9 + 2.1
Lactating
(foaling to 3 months)
400
500
600
95.8
118.4
141.0
1141
1427
1711
12.0
15.0
18.0
19.4
23.9
28.5
15.1
18.6
22.1
12.4
15.3
18.3
11.3 + 2.6
14.0 + 3.3
16.5 + 3.9
8.8 + 2.0
10.9 + 2.5
12.9 + 3.0
Lactating
(3 months to weaning)
400
500
600
82.4
101.7
120.9
839
1048
1258
12.0
15.0
18.0
15.1
18.7
22.2
13.0
16.0
19.0
10.7
13.2
15.6
9.7 + 2.3
12.0 + 2.7
14.3 + 3.3
7.6 + 1.8
9.3 + 2.2
11.1 + 2.5

Table 2. Nutritive Values of Common Horse Feeds ( pdf version )

Feed type Energy (MJ/kg) MJ/kg as fed Protein % Crude protein
Average Common range Average Common range
Wheat 13 12.5-13.5 12 9-15
Triticale 12 11.5-12.5 11 9-15
Corn 13.5 13-14 9.5 9-10
Barley 13 12.5-13 11 10-12
Lupins 13 11.5-13.5 32 28-36
Peas 13 11.5-12.5 25 20-27
Oats 12.5 11-13 10.5 6-12
Horse pellets (maintenance) 10 9-11 12 8-20
Horse pellets (stud or performance) 13 12-14.5 17 16-22
DDG Pellets 12.6 - 18 -
Wheat Pollard 11 - 15 -
Wheat bran 12 - 15 -
Rice Bran 11 - 14 -
Vegetable oils 38 36-40 0 0
Copra Meal (Max 10% of diet) 15 - 20 -
Lucerne hay 8.5 7-9 18 15-20
Clover hay 9.0 8-11 14 -
Pasture hay 9.5 6-11 12 8-16
Oaten or wheaten hay 8.5 6-10 6 5-10
Oat, barley or wheat straw 5.5 4.5 – 5.5 3.0 -
Grass hay (Teff) 8 6-8.5 11.5 7.5-16.5
Grass hay (Rhodes) 9 7.5-10.5 13 8-18
Grass hay (Native mix) 8.5 7.5 – 9.5 15 8-25
Oat, barley, wheat straw 5.5 4-6 4 3-5
Oat Hulls 5.3 5.3-5.4 3.8 -
Beet Pulp 11 - 8 -

 


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