Dr Nielsen gives us an insight into the diet and daily lifestyle of his successful racing Quarter Horse gelding, ‘Lambeau’.  Born, raised and trained at home, and kept permanently on pasture with his mom and sister, he is the shining example of why friendship, forage and freedom are simple, yet critical components of a happy, healthy, and successful horse. 

We’ll discover how long Dr Nielsen has been advocating forage only diets, consider the implications of such on performance horses, and discover why a forage only diet really is fit for the sport of kings.

This article was first published in the June 2013 issue of Horses and People magazine.

“Twenty years ago I would have never believed you could race horses straight out of pasture, and on an all-forage diet.  Now I know you can.”

Forage only diets are not a new concept. In fact, the horse has been surviving and thriving on large amounts of grass and other browse, for millions of years. Yet this approach is often far from the norm when it comes to feeding our horses in their domesticated setting.

After a flurry of research reporting the benefits of forage only diets for performance horses, we decided to investigate how this dietary approach holds up against the rigors and tradition of the racing horse world.

How long have you been feeding forage only diets, and what made you decide to go against the ‘grain’ of traditional performance feeding and management practices?  

When I arrived at Michigan State University in 1996, I was already preaching the benefits of turn-out time for racehorses to prevent unsoundness.  The University was racing horses and, instead of just making sure they got some turn-out each day, they opted to leave them outside on pasture. Turns out, they won the first two races that they were in that year!  Given that they had not won any races in several years, it was shown that you could win races with horses turned out all the time.

Then the question came up as to whether they should be getting fed any grain; it just seemed strange to not provide any grain to a racehorse! At the beginning of the season the horses were a bit chubby (probably a body condition score of 6 on a 9-point scale). Since the primary reason to give grain to a racehorse is to help meet energy demands, and the horses were already overweight from consuming too much energy on pasture alone, providing more in a grain ration made no sense. So, the first two wins for the University were with horses kept on an all-pasture diet and housing management system- a completely different feeding and management regime than what had been done for several years, with minimal success.

Do you have all of your horses on a forage only diet?

As far as is practically possible, yes. I have nothing against feeding grain if needed, but there are many horses that just don’t need it!  Previously, I have had lactating mares and growing horses that received a concentrated ration, and there are times when I have racehorses that require some grain supplementation to meet huge energy demands.

However, this is only if the pasture is not growing much, and the hay being fed is of lower energy density.

Often during the race season, which in this area occurs in the summer months, my pasture is good enough.

Here, the main concern is taking in too much energy, and the horses getting fat!  During this time, there is just no need for me to supplement their diet with grain.

With all that fiber, don’t your horses have a ‘hay belly’, and doesn’t his affect performance?

A hay belly is a concern. Typically though, as you begin to put speed on a horse, they get ‘tucked up’ and have less of a ‘belly’ on them.  However, they can still have a larger abdomen from carrying around extra fiber (and water that goes with it), and this can be detrimental to speed, particularly for the longer distances. For example, with the sprinters, you don’t want them carrying extra weight, but doing so over 250 or 300 yards is less of a concern, than with those racing a mile and a quarter.

On the positive side, there is mounting evidence to show that a ‘hay belly’ can help an endurance horse to stay hydrated. Water binds with fiber and is slowly released during a long ride to help cool the horse. While carrying the extra weight for great distances uses more energy, having water available and stored in the hind gut may prove much more valuable for the horse. This is particularly beneficial for horses in hot and humid climates.

Do you have to withhold hay before a race so he has less to carry in his gut?

Once I load my horses to head to the track (usually about five hours or so before they race), they don’t get any more food, unless I need to provide some hay just to keep them occupied. While there is research to suggest advantages of restricting hay a few days before a race to limit gut fill and reduce weight (as opposed to allowing them unlimited access to hay), in my pasture setup, dietary restriction is not possible. I’m not willing to stall my horses to restrict intake – I tried that, and it made the horses upset so I turned them back out.  Now I don’t bother stalling them at all, except for when we arrive at the track. I do believe gut weight would be a bigger issue if I was feeding hay during racing season, but with the immature forages they are consuming out on pasture, I don’t believe it is much of an issue.

What improvements, if any have you seen in your horses on forage only diet?

With my set-up it isn’t so much the forage only diet that brings in the obvious positive changes, it’s the constant access to being turned out. My horses are allowed to socialize, run, and play as much as they want; they have hardly any issues with lameness from training, and are much more content. They are also used to performing and living in all kinds of elements.

A few years back we won a race when we had 6 inches of rain during the weekend. Despite being drenched and racing in really deep conditions, my horse performed great. I believe living outside (yes, he had access to shelter if he wanted it – but horses often opt to stay out in the elements!) meant that he wasn’t bothered by the water on the track, and the rain in his face

Another benefit of the pasture housing setup is I rarely have sicknesses, particularly those associated with stalled horses in poorly ventilated environments.  For horses that are kept in stalls, a predominantly forage-only diet is even more critical to ensure they can at least benefit from eating for longer periods.  Compared to the traditional performance horse diet, high in concentrates & minimal forage, a high forage diet helps to prevent boredom and stereotypies, is critical for gut health, and reduces the likelihood of colic & gastric ulcers.

Have you received any negative feedback from others involved in the industry with regard to your feeding protocol? 

At the track, I don’t mention what I do as I’m sure they would believe it is the wrong way to manage a racehorse. I do mention it to my students though. I think more of them are realizing it is okay and a good thing to feed less concentrates, and that there are a lot of horses out there (including performance horses) that can do very well on an all-forage diet.

What does your horse’s daily diet consist of?

It’s pretty simple. During summer months when the pasture is growing well, that pretty much is it, along with a salt block of course. I don’t have a problem with supplementing with hay or concentrate if I feel he needs it – it’s just that most of the time, he doesn’t!!

Is it possible for all horses to be fed a forage only diet?

Yes, it is possible, it just may not be recommended for all horses. For example, horses that have high nutrient demands, may not be able to perform as well (whether it is in growth or athletic performance) if they receive a forage-only diet. The forage would need to be of very high quality to make this attainable, and not deficient in any of the nutrients.  In some locations that may not be possible.

With the type of work my horse does, will he be getting enough energy from the forage?

Many horses will, but some will not, it depends on the horse, the workload, and the forages being fed.  This is the reason why it is critical to body condition score your horse. Of all the nutrient requirements, energy is the only one you can look at your horse and see whether you are meeting their requirements.

What would a typical forage only diet look like for different classes of horses?

Growing youngsters, as well as a broodmares, need much higher quality forages than mature horses at maintenance, or even pleasure horses in light work.  Grazing pasture alone may present fewer options than being able to choose a variety of higher quality conserved forages. A good quality legume hay, such as Lucerne would be a good choice for those horses with a higher nutrient requirement, compared to mature horses that are relatively idle.

The less active and non-growing horses may be able to get by on a much poorer quality hay, with a protein, vitamin and mineral balancer to make up for any deficiencies in the forage.

As for senior horses, it totally depends on the individual.  We’ve done research examining nutrient digestibility of old horses versus middle-aged healthy horses and found there was no difference. However, if they are having health issues or have poor dentition, having a higher quality forage becomes much more critical, as does the fibre for component to ensure continued gut health.

With all horses, it is important to monitor body condition score to get an estimate of fat cover, and make sure that it is staying in the ideal range.

Will my horse be meeting his daily vitamin and mineral requirements?

Here is one of the most important aspects of evaluating whether an all-forage diet for a horse is possible: The forage must be analysed for nutrient composition, and evaluated against the nutrient requirements for that individual horse. There is no other way to assess the likelihood that the animal is getting sufficient vitamins and minerals.

If feeding hay, then you should only have to get a single batch analysed once, to know what you are providing. That’s useful if you are purchasing a large batch that could last you for an extended period. However, if buying in smaller batches, it can be impractical to analyse each batch. Likewise, pasture is always changing and it would not be practical to test every month for the average horse owner. From a practical standpoint, at least analysing your pasture once per year to determine mineral concentrations may be warranted.

Once you have a forage analysis, it is then possible to compare it with the requirements, as provided by the 2007 Nutrient Requirements of Horses by the National Research Council (commonly referred to as the 2007 Horse NRC).  The NRC also has a website that will allow you to input information about your horse and it’s feeding program, to determine if the diet is meeting the requirements of some of the major nutrients. If you see your forage is low in a given mineral, it may mean you need to supplement with some type of ration balancer.

Are there different types of forage with better vitamin/mineral contents to choose from?

Typically there are some that are better than others, but their nutrient content will vary greatly due to a number of factors such as location, growing conditions, soil quality, harvesting and storage. Truly, the only way to really know is to have the forage analysed. Forages that look and smell great can be poor in nutrient content, and forages that look poor can actually be good. One of the reasons feeding concentrates is popular, is that feed companies add additional vitamins and minerals to help ensure that requirements are met – regardless of the quality of the hay. It becomes a bit more risky if you leave concentrates out of the diet and don’t have your forage analysed.

Will I have to have my horse’s blood tested to see if his diet is lacking?

Blood testing is not that useful for most nutrients. The better approach is to analyse the feed and compare it to the animal’s requirements.

Is it going to be more expensive to feed forage over mixed ration?

Typically it is cheaper. If you compare it on a cost per pound, or cost per kg basis, usually roughages are cheaper. Truthfully, the more appropriate way to compare it is on a cost per nutrient basis. So, how much does it cost you per kg of protein, or per Mcal of digestible energy? That provides the truest way to determine which is cheapest. In most cases, the forage only diet is less expensive, but this may not hold true in all locations or with all forages.

Forage is not always the most palatable feed.  How do I introduce this to my existing horses, and those that are new to the property horses without them losing weight? Good forage is extremely palatable and horses often will hunt out forage if on a high grain diet. That being said, if given the choice between hay and grain, a horse will typically chose the grain. If given a choice between fresh green pasture and grain, the choice isn’t quite so obvious. Typically though, if they are not given the option, they will eat when they get hungry. It is like little kids, if you give them a choice between candy and healthy food, they will choose candy. But not given the option, when they get hungry, they will eat!  The problem is that many parents like to give their kids candy as the kids like to eat it, and it makes the parent feel good. Same with horses and their owners! People often give grain to their horses just because they know their horses like grain, and they want to make them happy.

Will my horse be more likely to colic on forage-only diet?

Generally, it is the opposite. An all forage diet (assuming there is nothing wrong with the forage and they have plenty of water available) is less likely to cause colic. One advantage is that to consume a forage diet, the horse has to chew more often.  Saliva release in the horse is linked to chewing, the more they chew, the more saliva that is produced. That saliva is useful in preventing colic and also buffering the acid in the stomach which helps to prevent gastric ulcers.

Can you condition a thin horse on forage alone?

If the forage is of good quality, probably, yes, although it may take longer. In fact, with starvation horse cases, a forage-only diet is critical in the early stages of rehabilitation.

Can my horse have a shiny coat on forage alone?

There are many things that can help to give a shiny coat. Dietary fat or oil can help but there won’t be much in an all-forage diet. A good brushing can do it, but that is up to the owner and is independent of diet.

However, horses can have a shiny coat on an all-forage diet too, especially if it consists of healthy green pastures. There are a lot of horses that dapple out and look wonderful when out on pasture consuming an all-forage diet. It is arguably a bit harder to achieve if it is an all hay diet. There is a saying that “Grass is alive and hay is dead”, and when forage is cut to be dried and made into hay, there is a decrease in nutrient content that continues gradually as hay ages. That shiny coat will be harder to achieve on an all hay diet, but if it is good hay and you put in some elbow-grease, it can be achieved!

Can I feed my laminitic, insulin resistant (IR), overweight horse a forage only diet? 

What special considerations should I take into account?  This type of horse will actually benefit from this type of diet, though horse owners need to make sure it is of lower quality (in this case, meaning lower energy). This type of horse can get into trouble on lush green, rapidly growing pastures as they are high in easily fermentable carbohydrates.

Avoiding the feeding of such to these horses is strongly suggested, but going for an all forage diet makes a lot of sense. It takes longer for hays to be digested so blood glucose does not rise as quickly when feeding hay as compared to grain, so the resultant increase in insulin is lower. For many horses, especially athletic horses, this is not a concern, but it certainly is for IR horses – those with cresty necks and a high body condition score.

Are there any other important management factors that should be taken into consideration?

The main thing is that you analyse the forage to make sure it meets requirements. That is probably the biggest concern, along with trying to ensure the right quantities are consumed. This can be easier said than done.

What are the advantages of a forage only diet?

The biggest advantages are that it matches up with how the horse evolved. They were designed to eat constantly, rather than in meals. On an all forage diet, that is generally how they are eating.  It is good for their health and for their behaviour. When eating, they are not bored. If kept in a stall a lot and provided a high grain diet with little forage, the odds are the horse is going to get bored and develop some stall vices, or stereotypies. If they can be kept outside, that is even better as they will likely have more exercise than when in a stall. That should aid in preventing unsoundness issues and respiratory problems, and also help with weight management.

Are there any disadvantages of a forage only diet?

It can be challenging to limit intake, especially when on pasture. I have raced horses that were overweight and that could have probably been faster if they lost a fair bit.  If their performance was more critical to me, than them being happy and healthy, I might be tempted to stick some of the overweight ones in stalls and limit what they eat. However, with my management system, I believe my horses are much healthier and happier the way things are, and that’s far more important to me.

Any more final thoughts on forage only diets?

I am privileged in that my horses do not have to be successful in order for me to feed my family. While my goal is to make money, I race horses as I enjoy working with them, and it allows me to experiment with ideas that may prove useful to the horse industry. Twenty years ago I would have never believed you could race horses straight out of pasture, and on an all-forage diet.  Now I know you can. Might my horses perform better on a high grain diet and stuck in a stall?  Maybe, but, maybe not. We’ve won our fair share of races straight off pasture, and on forage alone.

Managed this way, I know my horses are healthy and happy, and that is far more rewarding to me, than winning more races. Other than some of my horses carrying extra weight as they have taken in more calories on pasture than what is burned off through racing, I don’t think it has hurt at all, and I can argue it has probably helped a bunch, if for no other reason than I haven’t spent a lot of money on grain!

Top Tips for Feeding a Forage-Only Diet

  • Horses are bulk and roughage eaters and require a continuous supply of forage to ensure behavioural and gastrointestinal health.
  • The horse will consume between 1.5 to 3% of his bodyweight, in food, daily.  The majority, it not all, should be forages.  Feeding less than 1.5% of bodyweight in forage daily, is a welfare concern, and not advised; less than 1% will result in significant compromise to gut function.
  • Determine body condition score and monitor regularly to ensure your feeding program is meeting energy requirements.
  • Make all changes to the diet slowly, over a period of at least two weeks.  This is particularly important in forage based diets, to allow the gut micro flora to adjust to dietary change.
  • Ideally, forages should be offered on a free choice basis, and most horses will learn to self-regulate if given the chance.  Consult with an equine nutritionist and/or veterinarian to determine if your horse has any issues that may require a restricted or more closely monitored diet.
  • Start slowly with pasture and/or a low NSC, grass hay.  More nutrient dense legume hays, such as Lucerne, can be fed if necessary.  They offer a protein and digestible energy boost as part of nutritious forage feeding plan, but are very palatable, and should not be fed on a free choice basis.  Sugar beet pulp is another excellent forage-like feed, and can be used to supplement lower quality pasture and hay in a formulated nutrition plan.
  • Clean fresh water should be available at all times.  Rule of thumb: if you wouldn’t drink it, don’t expect you horse too!
  • Always, provide free access to salt, in the form of a white salt block.  If your horse avoids a block (and many do due to the roughened licking surface), provide 2 tablespoons of white table salt per day, divided between two feeds.
  • Have your forage analysed, it is the only way to know if there are any deficiencies or imbalances in your horse’s diet.  A vitamin/mineral/protein balancer may need to be fed, depending on your forage analysis results
  • Enjoy seeing your horse healthier, happier, and better behaved!

Dr Nielsen teaches senior-level courses in Equine Exercise Physiology and Advanced Horse Management, and also regularly guest lectures in the College of Veterinary Medicine and in the Department of Animal Science. His research focuses on the growth and development of the equine athlete with an emphasis on the prevention of skeletal injuries to performance horses through management, training, and nutrition. He is a Diplomat in the American College of Animal Nutritionists and recently served on the National Academy of Sciences Committee on Nutrient Requirements of Horses, and a licenced racehorse trainer.