What's in the Bin? Nutrition for Young Horses

Jul 23
4 min read

Setting young horses up for lifelong soundness

In mature horses we tend to use body condition as the leading indicator to adjust calories. With younger horses we also need to note skeletal development as well as body condition. Feeding young horses should focus on steady growth, and mineral ratios that balance forage, which should be the bulk of a young horse’s diet.

Foals at weaning are especially vulnerable to nutritional imbalances because their growth demands are so high and their digestive systems are still maturing.

We have just taken on two thoroughbred fillies (pictured above) - a weanling and a yearling. We will document their progress on our facebook page Sound Advice Horse Health, if you’re interested in following that.

Many young horses are turned out on pasture alone to grow, and while that’s great for their mental health, socialisation and movement, pasture-only diets can result in deficiencies that can manifest into problematic conditions that would not have arisen if their nutritional requirements were met from the get-go. Alternatively you have situations where owners of performance horses are keen to get going in competition, and overfeeding to promote early maturity.

Neither is ideal.

Key Considerations for Young Horse Nutrition

Copper & Zinc Deficiency: Both are crucial for proper collagen formation and bone mineralisation. Symptoms of deficiency include contracted tendons, poor cartilage development, dull coat, and slow wound healing.

Sound Advice Trace Mixes supply optimal copper and zinc (and iodine and selenium). Biotin Trace Mix is a great option, because it also supports hoof growth and coat quality.

Low Lysine: This essential amino acid is vital for growth and tissue repair. A deficiency can compromise skeletal development. Symptoms include poor muscling, easiest to see across the topline. An easy source of lysine is full fat soy bean meal. A little bit goes a long way. Read more here about amino acids.

Salt: Symptoms like pica (eating dirt or wood), poor hydration, muscle cramps, and fatigue (in young and older horses) are usually a sodium deficiency which is easy to resolve with salt added to the feed and access to a salt block.

Calcium:Phosphorous Imbalance: A skewed ratio (especially excess phosphorus) can disrupt bone remodeling. Calcium and phosphorous are the major minerals in bone and joints, and these are especially important to provide at an adequate level during growth.

This is not just a problem for babies. In mature horses, inadequate calcium intake will result in robbing calcium from the bone, and thereby weakening its composition and integrity.

A ratio of 1.5:1 of calcium to phosphorus is considered ideal, although in foals the ratio can be as high as 3:1. The easiest source of calcium in a feed is lucerne, and for phosphorous a good option is bran. You can read more about that here.

Epiphysitis: The Dietary Development Dilemma

What It Is: Epiphysitis (or physitis) refers to inflammation of the growth plates (epiphyses) in young, fast-growing horses — typically between 4 and 12 months of age. It’s part of the broader spectrum of Developmental Orthopedic Disease (DOD), but epiphysitis stands out for its dietary triggers.

Clinical Clues

Enlarged, warm growth plates around knees or fetlocks

Stiffness or discomfort, especially after exercise

Reluctance to move or shortened stride

Occasionally a “puffy” appearance in the joints with no heat or pain early on

Core Dietary Factors

Energy Overload: Diets too high in calories — especially grain-heavy or sweet feeds — accelerate growth unnaturally. Your horse’s diet can contribute to physitis by over-supplying calories and promoting excessive growth. Avoid excess protein or rapid growth diets, which can overstimulate bone formation without adequate structural support.

We have seen some young horses - particularly quarter horses being prepped for futurities - really struggle as their bone developed faster than tendons and ligaments resulting in significant pain and lameness. This manifests in short stepping, boxy hooves with high heels that look similar to club feet.

If a foal grows at a rate that exceeds the ability of the growth plates to ossify and adapt, structural damage in the bones can occur.

For this reason, fast-growing foals consuming a high level of soluble carbohydrates (grain based or rich pasture) are prone to developing physitis.

Avoid overfeeding young horses “just in case” — growth spurts need slow, steady nutrition.

Consider low-GI grain alternatives like soy hulls, lupins or beet pulp. Forage, whether that’s hay or pasture, should supply the majority of their calories.

Before and After

This is our filly Splendour on the day she arrived, and below, how she looks today.

Here at Sound Advice we always encourage owners to design their diets specific to their particular horse in the current circumstances, which will need tweaking over time. The principles are the same:

The bulk of calories and nutrients are supplied by pasture and hay.

Hard feeds only supply what’s missing from forage.

Minerals, amino acids and extra calories should be supplied as much as possible by feeds.

Supplements should only add what is missing from that.

This reduces costs overall, and encourages optimal horse health naturally.

Here is what we are feeding our two new fillies, meeting all their nutritional requirements for less than $10/day.