Proteins in Horse Nutrition Don’t be Confused

Proteins in Horse Nutrition Don't be Confused

There is a lot of confusion about the role of proteins in horse feeds. Can you feed too much protein? Does it cause problems? Does protein cause your horse to heat up? Why proteins are important?

Amino acids are the building blocks of protein and play an important role in muscle development, hoof growth and coat condition as well as immune system, nervous system and hormonal function. In addition, amino acids supply the horse with a valuable source of energy. Most of the amino acids required by the horse can be manufactured in the horse?s body. There are however 10 amino acids that cannot be manufactured by the horse and thus must be supplied in the diet: these are termed the essential amino acids.

Failure to provide the essential amino acids in the diet will slow growth, limit muscle development and reduce the horses feed use efficiency Lysine is the first limiting amino acid in a horses diet (i.e. it is the one most likely to be deficient in the diet). Threonine and methionine are thought to be the second and third limiting amino acids in a horse?s diet

Some important facts

1. Dietary protein is expressed as a % and is calculated by measuring the nitrogen content in the feed and multiplying by 6.25. Most feeds contain proteins, but generally grains supply energy and some protein, hay provides some protein, and the protein meals (cottonseed, canola, sunflower) are used if a source of protein is required). Some feeds such as coconut meal provide both protein and energy.

Feedstuff

Protein %

Cottonseed meal

40

Canola meal

35

coconut meal

20

Lucerne

10-20

Barley grain

10 -12

Oats grain

10 - 12

Wheat

9-14

Corn

9-12

2. Amino acids are only absorbed from the small intestines. Not all the protein is absorbed and Biological Value (BV) is the proportion of the protein that is eaten that is absorbed from the intestines.  In some feeds that have been over heated, or contain compounds such as tannins, the BV is reduced and the protein is not absorbed by the horse. It is necessary therefore to know both the % and the BV of protein in the feed.

3. Calculating protein intake

When looking at the protein content of a feed, you must consider it as part of a complete diet. CoolStance for instance is a high protein feed (21% crude protein), however it is designed to be fed in conjunction with lower protein feeds like grass hay (9% protein). Therefore when considered as part of a complete diet, the total protein is only 10% -13% (see below).  

Protein required and received by a 500 kg horse being fed CoolStance (21%CP) and 9% crude protein (CP) grass hay.


Activity Level

Cool Stance (kg/day)

Grass Hay 9% CP (kg/day)

CP Requirement (g/day)

CP Supplied (g/day)

CP % in total feed

Upper Limit# (g/day)

Spelling

0.5

8.25

656

847

10%

N/A*

Light Work

1

9

820

1020

10%

1600

Moderate Work

2

9.25

984

1252

11%

1800

Heavy Work

3

9.5

1312

1485

12%

2000

Pregnant Mare (Late)

1

7.75

866

907

10%

N/A*

Lactating Mare (Early)

4

8.5

1427

1605

13%

N/A*

4.  Protein can provide a source of energy.

Substrate

Kcal/g

KJ/g

Carbohydrate

4

16

Protein

4

16

Oil

9

38

If you feed high levels of protein it is simply used as an expensive source of energy. At very high protein intakes, the heat increment associated with digesting the protein is high, and this can cause the horse to produce a lot of waste heat and increase the heat load. Under hot conditions this can cause increased sweating and cause electrolyte loss and reduced performance.

5. Can you feed to much protein?
It is often suggested that protein makes my horse hot, i.e. fizzy behaviour?. This is a myth. So why does my horse become 'hot'? It is usually because the feeds contain a level of NSC above 12-15%. The term hot is confused with the heat increment discussed above.

6. Role of proteins in hoof and hair growth.
The coat mane and tail are formed from keratin. Keratin is formed from the sulphur containing amino acids methionine and cysteine. Similarly, the hoof wall is made of keratin, which again is formed from S- amino acids. This is why feed products such as CoolStance coconut, which contain high levels of S-amino acids support good growth hooves, and coat, manes and tail.
7. Protein quality.

It is essential that feeds contain good quality proteins for body function. Most plant proteins contain an adequate balance of amino acids, and horses rarely suffer protein deficiency unless very poor quality feeds are fed. In that case, the horse will be suffering a combination of energy, protein and mineral deficiency.

8. Do energy feeds provide amino acids?
Cereal grains such as barley and oats are commonly used as an energy source in horse feeds. Some oil based energy feeds such as CoolStance coconut meal have a superior essential amino acid profile, and therefore not only provides a readily digestible and 'safe' source of energy, but will make a valuable contribution toward satisfying your horse's essential amino acid requirements to promote muscle development, hoof growth and brilliant coat condition.