Who Wants More Muscle? Part 2

The previous article was about the 3 things you need to build muscle in your horse; work, to stimulate the muscle to want to grow; leucine, the branch chain amino acid that switches on muscle protein synthesis; and a ready supply of the other amino acids needed to build new muscle.

Which left us with the question of which feed ingredients contain the best source of leucine to help switch on the muscle protein synthesis process.

The best ingredients to help your horse build muscle

1. Whey protein concentrate. This ingredient contains around 80% crude protein (depending on the brand) and has over 10 grams of leucine per 100 grams. Certainly, the richest source of leucine (and all of the other important essential amino acids) you can get. It works, but it is not cheap. If you use whey protein, be sure to use it very strategically and feed it to your horse within 15 to 30 minutes of finishing a work session.

2. Soybean. Soybean is well known to be the richest plant source of essential amino acids, including leucine. Soybean meal contains 47% crude protein and will give you 3.5 grams of leucine per 100 grams of meal. Full fat soybean is 36 to 38% crude protein and will give you about 2.7 grams of leucine per 100 gram serve.

3. Brewer’s Yeast. Brewer’s yeast is also a handy source of leucine. It contains 50% protein and will give you 3.2 grams of leucine per 100 gram serve. Like whey though, it’s a relatively expensive option.

Other common feedstuffs and their protein and leucine content are shown in the table below.

There are also of course BCAA supplements available (for humans and horses) that can be used. You should be able to find information on these in FeedXL, in the Blue ‘Supplements’ tab, under ‘Protein & Amino Acid Supplements’.