Protein Bioavailability For Horses


This table lists the bio-availability of the various feeds used for additional protein in horses but they are based on human studies.  Values that have a range is because of different information available.

The bio-availability of proteins can vary between different horses and can even differ in one horse depending on factors such as gut inflammation and fasting.  I think it safe to assume that horses with gut inflammation or who are on medications (especially proton pump inhibitors – ulcer medication) will definitely have a reduced absorption and bio-availability of proteins.  In addition, horses in carbohydrate dependency (fed sugar every day of the year) will also be self consuming their own proteins (top line loss).  Feeding excessive amounts of proteins may also cause the horse to convert the fed proteins into sugar in the gut when the amount of daily carbohydrates in excess of needs are not reduced..

Basically, this list is to show you that in testing conditions, not all proteins are absorbed equally.  Feeding the best quality protein (no hulls, no fiber, no sugar, no oils) with the best bio-availability AND offering several protein sources will give your horses the best chance of absorbing all the amino acids to produce a great top line, a robust immune system, and a strong connective tissue system.

Protein Bioavailability (approx)
Egg White 100%
Whey Concentrate 96%
Soybean whole 96%
Soybean Meal 80%
Flaxseed Meal 77%
Dried Split Peas 65%
Wheat Gluten 64%
Grass and Legume Hay 50 – 56%
Hemp Seeds 33 – 87%
Sunflower Meal 30%
Chia Seeds 29%



  1. Hello, Does bioavailability equate to total digestible nutrition? My horse gets fed coastal hay as his main forage. I cannot find the bioavailability of it, but can find the TDN. Thank You.

    1. Sorry for the delay – a glitch. But the bioavailability for most hays are around 50%. I will update this chart to say not just alfalfa but grass and legume hays. Thanks

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