Building a strong horse starts from the moment the foal is born. The first few hours in a foal’s life are crucial because they have to get the colostrum they need to remain healthy. During the first few months of their life they are getting a majority of nutrients from the mare in the form of milk as well as nibbling on some forage and grain that might be fed to the mare.  At or after two months of age you should put the foal on a creep feed diet which, along with the mares milk should keep the foals rate of gain steady, preventing them from experiencing a big growth spurt when placed on the weanling diet. This growth spurt increases their risk of developing an orthopedic disease, such as Physitis, an inflammation of the growth plate, mainly affecting the hock and stifle joints. But what about after you wean them?  Feeding the weanling can be a tricky issue as you have to make sure that they are getting enough forage, grain and water in their diet. Unfortunately, many weanlings are deficient in crucial nutritional requirements and one of the major nutrients they may be deficient in is minerals.  

Water Requirements
The most crucial and most limiting nutrient is water and the weanling needs to consume at least 1 percent of their body weight. It is important to remember that this is just the minimum amount, but it is safe to keep as much water as the weanling wants to drink available as long as it is clean and fresh.  The amount of intake will vary greatly depending on the type of feed you choose to feed your weanling. The water content in hay and pasture can vary greatly in the amount of water they contain. For example, hay and concentrates will contain only about 10 percent moisture which will not cause a decrease in water intake; however, when the weanling is grazing on lush green pasture you may see a decrease in water intake, because the fresh grass may contain up to 80 percent moisture.  So they may be fulfilling some of their needed water intake by grazing lush grass.
Wintertime can pose a threat to the amount of water your weanling will want to consume. Make sure the water is cool in the summer and warm in the winter. Water heaters can be purchased at your local farm supply store which will prevent ice from forming during the winter.

Nutritional Requirements of a Weanling
1.    The total daily requirements (forage/hay and concentrate) for the weanling are 2 to 2.75 percent of their body weight on a dry matter basis.  Keep in mind when you first wean your foal, they might not be consuming this amount due to the stress of being weaned, but this is the percentage that you ultimately want to work towards.      
2.    When the weanling is consuming hay he/she will need to consume 1-1.25 percent of their body weight on a dry matter basis.  
3.    The weanlings concentrate requirement should be around 1-1.50 percent of their body weight on a dry matter basis. To figure out how much you need to feed we have to take into account the water content in the hay first. As a rule of thumb, grass and legume hays, and concentrates contain about 10 percent water and 90 percent dry matter so you need to take the amount on a dry matter basis and divide it by 90 percent, for example 4.6lb/0.9. So the amount that you will need to feed is 4.14 lbs of hay/concentrate per day on an as fed basis.

Nutrient Requirements and Calculations
There are many different minerals that the weanling needs for proper growth and development. The two most important minerals needed are calcium (Ca) and phosphorous (P) fed as a 2:1 ratio, for example if you have 2g of calcium you will need 1g of phosphorous to balance the ratio.  These two minerals are the No. 1 minerals in which weanlings and mature horses are going to be deficient. The weanling needs about 34g of calcium and 18g of phosphorous a day to meet their growth requirement. If you find that your hay will not fulfill your calcium requirement never try to balance the ration by adding more grain, because concentrates are higher in phosphorous than they are in calcium. If you do this, your calcium to phosphorous ratio will be miscalculated, and proper growth will be disrupted.

Mineral Deficiencies in the Weanling
The first and most common mineral deficiency is calcium and phosphorous.  The mineral content of the equine bone is comprised of 34 percent calcium and 17 percent phosphorous. These minerals are required to support skeletal growth and development. A deficiency can cause delayed bone mineralization and delayed growth.  Improper growth during this time may cause lameness issues later in life as well as more fracture potentials of their limbs. Many grasses do not meet the calcium/phosphorous requirements of the weanling and grains definitely do not meet the calcium requirements so supplementation may be essential for your weanling’s health.  
Salt deficiencies can cause decreased appetite, weight loss and can cause pica (ingestion of dirt), which can cause the weaning to become infested with internal parasites; however, to much salt and not enough water can cause salt toxicity and may decrease food intake as well. Selenium deficiencies can cause a decreased immune response and can cause nutritional myopathy (white muscle disease). If your weanling is deficient in selenium, a deficiency in vitamin E may also be present.  However, there is a narrow range between selenium deficiencies and toxicities. Copper and zinc deficiencies can cause risks of developing orthopedic diseases and ossification defects.

To Supplement or Not to Supplement?
You must first choose what type of forage best suits your situation. What you will probably find is that your forages will be deficient in calcium and phosphorous so you will need to provide them with free choice to keep their mineral requirements in check, and do not forget to test the amount of minerals in your water. If you choose to feed hay and grain, first determine what type of forage you will be feeding and test to see what the mineral content is.  If you feed grass hay it will be lower in minerals than legume hay like alfalfa.  The next step is to determine if the hay was cut pre-bloom, slightly mature or mature. You want to feed the pre-bloom alfalfa hay because it will have the most available minerals, protein and digestible energy for your weanling.  Bottom line, know your weanlings weight, amount of nutrients he/she will need to consume and test the forage and water that you have and supplement from there. Most of the time you will need to supplement with a free-choice mineral so read the labels carefully on the bag and determine which one will best suit your weanling’s needs.
Dr. Beth Walker is an animal science professor at Missouri State University. She composed this article in conjunction with Susan Demster and her 2008 Feeds and Feeding class.


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