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Why Feed More Than Hay? Part II: Vitamins and Minerals

Another common reason to supply your horse with more than pasture and/or hay is to enrich their diet with vitamins and minerals. Most, if not all, forages lack proper levels of certain trace minerals, so every single horse owner should find a way to offer these to their horse(s). There are many ways to do so- read on...

If you have not already read "Why Feed More Than Hay Part 1: Calories", HERE IS THE LINK.

At no time is vitamin and mineral nutrition more important than in pregnant mares and growing foals! In this article, we're going to explore how a local grass mix does or does not meet the vitamin and mineral requirements of this little guy- an adorable, 6 month old Paint weanling named Zephyr. Zephyr's owner contacted me before she had even brought him home wanting to know how to best meet his nutrient needs. She was new to baby horses and new to the temperate region of Montana. By taking steps to understand the local grass hay and pasture, she is now providing Zephyr with the right levels of critical nutrients for long term immune health, skeletal soundness, muscle development and more!

Zephyr was weaned in the late summer of 2021 and moved to his new home in Montana where he has companionship, plenty of fresh water, lots of room to run, and excellent nutrition provided by one simple product.

Understanding Zephyr's Primary Forage

Zephyr's owner, in an excellent move to take the guesswork out of his diet, sampled two lots of hay that she had acquired for the winter- a local 1st and 2nd cutting mixed meadow grass hay. This forage is perfectly meeting his caloric needs, so we can move immediately to the second most common reason to feed more than hay- vitamins and minerals. You're going to see the results of those forage tests below, and I will point out some of the mineral results. Instead of breaking down every single nutrient that Zephyr is known to require, I'm going to focus on the most important basics. For most young horses without unique special needs, covering these basics well will be more than adequate for ensuring good growth and health long term.

#1: The Calcium and Phosphorus Ratios

As we all know, the major minerals calcium and phosphorus are principle components of bone which is growing quickly in young horses. What you might not know is that the body requires a ratio of these minerals for proper assimilation; more phosphorus than calcium can cause disease and vice versa. A mature adult horse can handle ratios of calcium to phosphorus anywhere between 1.5:1 to 8:1, but it is thought that this window narrows in the young horse- ideally closer to 2:1 or 3:1.

First and foremost, we need to ensure that there is ALWAYS more calcium than phosphorus in the young horse diet. Therefore, one of the very first things that I check on a forage test is this ratio. As you can see below, the first cutting grass mix has a ratio of about 1.5:1. This is definitely borderline, so it's very important that we do not add any high phosphorus ingredients to Zephyr's diet such as beet pulp, grains, or rice bran. An easy way to balance this ratio better is to offer a small amount of alfalfa hay as part of the forage balance since alfalfa hays always have very high calcium to phosphorus ratios. We could also provide a ration balancer with added calcium.

1st Cutting Local Grass Hay Mix- Check calcium and phosphorus ratios

#2: Trace Minerals

The next thing to check for on this forage test are the levels of 3 VERY critical trace minerals; zinc, copper and selenium. Every horse owner needs to memorize these three trace minerals and ensure that they are being provided in the supplemental diet, because I have yet to come across a forage result that was adequate in all three. These three trace minerals are extremely important for the parts of the horse that we see- the skin, coat, and hooves. They are also very important for the systems that we can not see such as immunity and reproductive health.

I've provided a chart below that shows what 10 pounds of 2nd cutting grass hay is providing Zephry (roughly 2.2% of his current body weight in hay). *We are also assuming that he is getting a couple pounds per day from the pasture. Compared to his 6 month of age requirement (assuming 1,100 lb mature body weight) the hay is NOT providing anywhere near his zinc, copper or selenium levels. Therefore, it is absolutely critical that we provide him a daily supplement that provides these trace minerals. There are many ways to do this for Zephyr or any mature adult horse for that matter- jump past the chart and forage result to find out your options.

Note: Though selenium was not actively measured in this forage test, we can assume due to location and regional averages that there is little to no selenium. This may not be the case is in parts of Central USA and other hot spots of selenium around the country. Find out more at U.S. Geological Survey website.

Trace Mineral

Requirement in Milligrams (6 mn; mature weight of 1,100 lbs)

Contained in 10 lbs of 2nd Cutting Tested Grass Hay (mg)

Difference (mg)




146 mg (32% of req't)




34 mg (37% of req't)



Unknown- assumed zero

-0.54 mg

#3: Protein

A quick note about this forage test result. At 8.7% and 10.4% crude protein, I believe these forages to be inadequate for a young growing horse. A crude protein report is just that- CRUDE. We do not know the individual amino acid content and quality, but with relatively low crude protein levels, low digestibility of first cutting, and Zephyr's future in mind, I would highly suggest a ration balancer for this young horse (any brand). In my opinion, a simple vitamin and mineral product will not suffice.

2nd Cutting Local Grass Hay Mix- Check Trace Mineral & Protein Levels


There are several ways to meet a horse's trace mineral requirements. What you choose will depend on your horse's requirement, management situation, your budget, and product availability more than anything else. There is a TREMENDOUS amount of diversity out on the marketplace too including various nutrient levels, sources of nutrients (i.e. organic vs inorganic compounds), and serving sizes. If you need help weeding through all those products and options, you can schedule a FREE 15 Minute Discovery Call now. Otherwise all these products can basically be divided into...

  1. Trace Minerals Supplements (loose or pelleted): provide only significant levels of trace minerals needed in milligrams per day; usually come with a small scoop and feed <8oz/day. Examples include HorseGuard, Vermont Blend, Cal Trace, ect to infinity ;). Check out my reviews at Rate My Horse Supplement.

  2. Ration Balancer: a pelleted product complete with trace minerals PLUS enough volume to provide critical amino acids and major minerals too. Will feed between 1-3lbs per day for average horse. Again, this is my TOP recommendation for Zephyr considering the relatively low crude protein of this forage test.

  3. Lick Tubs: There are several lick tubs on the market today designed for horses out on large pastures in herd groups. There is some unique management required of these products and there are many formulas, but they are a good solution for big herds.

Zephyr at 6 months! His owner will see his coat really bloom and hooves grow strong as he develops in the coming year on a ration balancer.


For many reasons beyond the scope of this article, Zephyr's owner chose the Purina Enrich ration balancer to supply him with trace minerals and protein lacking in the forage. One note that I wanted to make is the importance of reading the feeding directions for ration balancers. The nutritionists behind these products do a good job of calculating for you and providing specific directions for inclusion as the young horse develops over time. It may surprise some of you to know that the youngest horses need the largest amounts of key vitamins and minerals. Due to the extremely low zinc and copper levels in the forage, Zephyr's unknown mineral status, and his age and weight, I recommended that he get the full 2.5 pounds per day. On this simple, affordable, yet nutritionally robust diet, Zephyr's winter coat will shed into a beautiful summer coat, his hooves and bone will grow strong, and his immune and digestive systems will be healthy! One or more of these health blocks could easily be missed if Zephyr was only fed hay, but with a little effort and planning his owner has set him up for success!

Directions for Feeding Purina Enrich Plus Ration Balancer

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