They Are What They Eat

January 7th, 2016 8:32 PM | No Comments

[Originally published in the 2016 Breeders' Guide]

Screen Shot 2016-01-07 at 9.20.48 PMKnowing what to feed a broodmare and her developing foal can be a bit overwhelming with all of the options currently out there.  Most people know that they have vastly different nutritional requirements from active adult horses, but where do you start from there?  You might have questions like “Do they need to be on additional supplements?” “What supplements do they need to be on?” “Can they have too much or too little of a particular mineral or vitamin?” or “What should be my foal’s first solid food?”

The world of equine nutrition can be very confusing, but fortunately a lot of research has been done in the field over the years and both veterinarians and scientist understand nutritional needs better than they ever have before. 

Show Horse Today sat down with Dr. Josie Coverdale of Texas A&M University to get answers to some of our biggest questions about properly feeding broodmares and foals.  Dr. Coverdale teaches courses in equine nutrition in Texas A&M’s highly acclaimed Equine Science department and focuses much of her research on this topic. 

How do the nutritional needs of a mare in foal differ from a mare that isn’t pregnant? Do they change throughout the pregnancy?

The nutrition needs of a mare change as pregnancy progresses.  During the first two trimesters of pregnancy (first seven months) there is minimal foal growth and the mare can be fed a diet based off good quality forage and the minimal incorporation of grain.  While the amount of grain fed during pregnancy should not be high, the balance of nutrients is important. 

Resist the temptation during this time to mix feeds and create your own diets.  Choose a high quality feed formulated for the needs of a pregnant mare.  When approaching the beginning of the third trimester, it is important to gradually start increasing the amount of grain in your mare’s diet.  This is in preparation for the majority of fetal growth that takes place in the third trimester. 

The best way to monitor the success of your mare’s nutritional program is to determine her body condition score.  Broodmares should ideally be a body condition score (BCS) of 6, and maintain this score throughout pregnancy.  This is relatively easy during the first two trimesters when fetal growth in minimal, but once the third trimester starts, the mare will begin to pull nutrients from her own body if her diet is not ideal.    

Screen Shot 2016-01-07 at 9.20.27 PMWhat is an ideal feeding program for a mare in foal to make sure the foal develops properly and the mare has adequate nutrition throughout gestation? What deficiencies are most common and what are their signs, and how can they affect the mare and her developing foal?

The most important aspects of a mare’s feeding program are quality forage and a well-formulated grain.  Mare owners should consider testing their hay and/or pasture for nutrient content.  This information can then be discussed with a local veterinarian or equine nutritionist to determine if you have any nutrient deficiencies.  The most common problems are low protein and mineral imbalances. 

Many problems with mineral content in forage can be due to geographical location.  Testing your hay and pasture gives you an idea of whether the forage can meet the needs of your mare during early pregnancy, and if not, how much grain you should supplement to meet her needs.  Choosing a commercial ration designed for pregnant mares ensures you are meeting nutrient requirements of both the mare and foal.  These formulations contain high quality protein and careful mineral balance.  Once again, the ideal way to monitor the success of your diet is through the mare’s BCS.  If your mare has less than a score of 6, your program is not meeting her energy needs.  If greater than 6, you are over feeding.  

Before breeding a mare (either a broodmare or maiden mare), are there any changes that should be made to their current feeding program?

Prior to breeding, a mare should ideally be a BCS of 6.  If not, the owner should be increasing her nutrition to help her reach this desired score.  Research is clear that mares at a BCS of 6 or greater have improved reproductive efficiency.

What are some of the most common mistakes or misconceptions about feeding broodmares?

In the industry I see two common problems; mares that are over fed and those that are underfed.  Many well-meaning owners think at the time of conception that the mare “is eating for two” and needs lots of supplemental nutrition.  We are still fully researching the effects of over feeding mares during pregnancy, but early work suggests it is not beneficial, and it is expensive. 

When do foals usually begin to eat solid food in addition to their mother’s milk, and what is the best feed to provide?

Most foals begin to investigate and consume solid feed in the first week of life.  After two months of age, milk production in the mare begins to decline, and foals must start to consume solid feed to meet their nutritional needs. 

Ideally, foals should have access to solid feed in the first month of life in order to adapt to it before mare milk production starts to decline.  This first diet of solid feed should consist of a commercial diet formulated for foals (often called creep feed) and quality forage.  The most important aspect of creep feeding is management.  Ideally, creep feed should be provided free choice to foals in an area where mares cannot reach it. 

Screen Shot 2016-01-07 at 9.29.38 PMHow do the nutritional needs of  foals change from the time they are weanlings to when they begin training and go on to begin their performance careers? What is the adequate protein/fat/calorie intake range, and what vitamins/minerals do growing horses need?

Yes, young horses do require a change in diet as they progress from foal to weanling to yearling.  In general, nutrient requirements decrease as horses age because the rate of growth is slower.  However, this does not necessarily mean you need to change diets.  Choosing a commercial diet formulated for growth is key to success! 

Typically, weanlings receive diets high in grain and low in forage, while older horses can better utilize forage and require less grain in their diet.  Commercial diets formulated for growth contain a balance of carbohydrate and fat for energy and a careful mix of minerals to support bone and joint development.  Minerals such as calcium, phosphorus, copper, zinc, and manganese are all important for proper growth and must be provided in adequate amounts and ratios. 
What are some common growth complications and developmental disorders associated with inadequate nutrition and deficiencies? Can any of these be corrected by adjusting the feeding program, or is the damage already done?

The incidence of developmental disorders in our industry is high, and nutrition can certainly play a role in these issues.  The important thing to strive for during the development of young horses is consistent growth.  Many owners pay little attention to the nutritional programs of their weanlings, and then, attempt to make up the difference by feeding high grain diets to long yearlings in training. 

There is no stage of growth that is more important than the others, and special attention must be paid to young horses while they are rapidly growing.  Providing consistent nutrition and monitoring growth rate (weight, BCS, height) are important.  Early signs of joint disorders may not be able to be “fixed” by nutritional changes, but certainly we can help adjusting the diet to the needs of the horse. 

How has nutritional knowledge for broodmares and developing young horses changed over the years?

I do not think we have made any large changes, but rather the research has more accurately defined requirements for pregnancy and growth.  Diets now have a mixture of calories from fat and carbohydrate, reducing dietary starch while still maintaining growth rates.  This helps keep meal sizes small for mares and colts.  In the growing horse, we have learned more about amino acid needs, mineral requirements, and the potential impact of nutrition during pregnancy on the resulting foal.  Our formulations are now geared towards optimal performance of the mare and foal, not simply meeting nutrient requirements. 


While there is never a one-size-fits-all feeding program for any horse, knowledge of the key basics and nutritional needs gives breeders a good place to start.  If you have additional questions and concerns, contact your veterinarian to develop a diet that suits the specific needs of your mare and your foal. 

About Dr. Coverdale

Dr. Josie Coverdale is an assistant professor at Texas A&M in the Equine Science department.  She has focused much of her career teaching both graduate and undergraduate equine nutrition courses, and has made it a focus of her research. Some of her research projects have included forage utilization and hindgut fermentation, use of by-product feeds, probiotic effectiveness, passive immunity in foals, as well as nutritional influences on equine exercise physiology.  Future research plans include investigating nutritional requirements for optimal growth and development, energy metabolism during exercise, and nutritional influences on reproduction.

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