B vitamins – Vitamin B1, Thiamine

B vitamins – Vitamin B1, Thiamine
9 September 2019 | Foran Equine

Vitamins are crucial for health and body function in the equine diet, with roles in performance, growth, reproduction, energy maintenance and immune system function. B vitamins are a group of water-soluble vitamins that each have unique chemical names and functions which are collectively known as the B vitamin complex, find out more here. The B vitamins play an important role in energy metabolism through the utilisation of protein, carbohydrates and fats as well as nerve transmission and red cell production.

What is B1?

Vitamin B1, also known as thiamine, is important in processing carbohydrates, protein and fats as well as playing a role in nerve stimulation and transmission. Three enzymes that are important in carbohydrate metabolism require B1. Two of them help to break down glucose which eventually becomes adenosine triphosphate (ATP). ATP is a small energy-carrying molecule found in the cells of all living things and is the main source of energy for most cellular processes. The third enzyme is required in the pentose phosphate pathway. This pathway has several functions, the most important of which is to provide cells with nucleic acids which make up DNA.

Where does my horse get B1?

B1 is well supplied in grass and is one of the few vitamins that can be found in cereal grains. Barley contains the most B1, followed by wheat and then oats. By-products, such as rice and wheat bran, are also high in B1. Brewer’s yeast is often found in feedstuffs and has high levels of B vitamins, including B1.

As with other B vitamins, B1 is synthesised in the hindgut and horses can usually produce adequate levels. However, many factors can influence a horse’s ability to synthesise B vitamins such as during times of stress or high exertion (e.g. travelling, racing, competing), horses with diets low in fibre or those with reduce appetite. These horses that are unable to synthesise sufficient levels of B1 may benefit from it being supplemented in the diet.

What happens if my horse gets too much or not enough B1?

As a water-soluble molecule, B vitamins are not stored by the body and any excess supply is excreted in the urine. Consequently, over-supply or toxicity is extremely rare, but this also means B vitamins must be consumed in the diet in sufficient quantities. Whilst clinical deficiency is uncommon, deficiencies in B1 can include reduced growth rate, a lack of appetite leading to weight loss and nervousness. Horses that are B1 deficient can seem nervous or stressed, so B1 can often be found in calming supplements.

If you’d like to find out more about B vitamins or discuss your horse’s diet, get in touch with one of our experts.



Manthe, B. N. and Youngs, C. R. (2013) An Overview of Vitamin Requirements of the Domestic Horse. Natural Sciences Education, 42(1), 179-184. DOI: 10.4195/nse.2012.00002



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