Fat, Protein and the Performance Horse

By Dr. Karen E. Davison, Ph.D., Purina Mills, LLC

In recent years, much attention has been paid to dietary fat and protein levels for performance horses. The question continues to be what is the perfect combination of these two nutrients. The answers are as varied as the performance horses themselves. One reason for the variability is the differences between types of performances. When considering performance of a predominately aerobic nature, such as endurance horses, higher levels of dietary fat may indeed help support the energy demands of the work. On the other hand, when the performance is primarily anaerobic work, such as sprint racers, glycogen will more likely be the limiting factor to performing at a high level.

Desired protein levels in feeds for performance horses have come full circle over the past 20 or so years. For years, more was considered better. Many "high performance" feeds were 16% protein or higher. In the last few years, high protein levels have begun to be considered as a performance liability. In many cases that is just as wrong as feeding too much protein. The concern about high protein feeds comes from the idea that excess protein must be broken down in the system and this costs energy. Also, horses on high protein diets tend to urinate more frequently to flush out the excess protein. For horses that are sweating profusely over several hours, the increased urine output compounds the difficulty in keeping these horses hydrated. This is usually not a concern in anaerobic type performance horses, who work at high intensity for short duration. These horses may certainly sweat a great deal, but usually it is not over a period of several hours. In addition, anaerobic athletes may also have a greater protein requirement to repair damage to muscle tissue that is more likely during anaerobic-work than during the longer, lower-intensity exercise of aerobic work. Obviously, this is not a simple question with a simple answer.

When deciding on a feeding program for a performance horse, the following are important considerations:

1. How old is the horse?
2. What is the type and level of performance?
3. Look deeper than fat and protein levels and terms like "higher" and "lower". Determine totalamount of nutrient in the diet vs. percent protein in the feed, protein sources (i.e. amino acid balance), energy level of the feed, nutrient balance in the total diet, quality and consistency of product.

How old is the horse?

Consider that a young performance horse is still growing and therefore has different protein requirements than a mature performance horse. The quality of protein, meaning the amino acid balance provided, is critical to support the building of tissues for growth. A low protein feed will not provide adequate amino acid balance, unless it is fortified with the amino acids themselves. Typical lower protein ingredients such as oats and corn will not have adequate lysine, methionine or other necessary amino acids to support optimum growth. Depending on the breed and the individual, the horse may still be growing into his 4th year and even into his 5th and 6th year for some breeds. Therefore, a 2-year-old race horse has different protein requirements than a 12-year-old jumper.

What is the type and level of performance?

Anaerobic exercise (maximum effort for short duration, such as jumping, cutting cattle, barrel racing, sprint racing, etc.) results in more muscle breakdown and need for repair than aerobic exercise (submaximal effort for long duration). They also don’t typically have the same difficulty remaining hydrated as do endurance or competitive trail horses. So, protein levels that may be excessive for a mature competitive trail horse, may just be adequate for a 3-year-old reining horse. Also, a weekend hunter/jumper will not be taxed by any potential physiological burden of excess protein the same as a 100-mile endurance horse.

Look deeper—amount vs. percent

Oats - 10 lbs X 11.5% protein = 1.15 lbs of protein

Omolene 200 - 7.5 lbs X 14% protein = 1.05 lbs of protein

Note that the horse eating oats, the lower-protein feed, consumes more total protein than the horse eating Omolene 200, when feeding rates are considered. Omolene 200 will provide a better amino acid balance than oats, but less total protein.

Total amount of nutrient in total diet

Pretend that in the previous example, the horse would eat 10 pounds of Omolene 200. Also assume that horse will eat 15 pounds of hay.

Oats: 10 lbs X 11.5% protein = 1.15 lbs protein

Omolene 200: 10 lbs X 14% protein = 1.4 lbs protein

Hay: Grass 15 lbs X 9% protein = 1.35 lbs protein

Alfalfa 15 lbs X 18% protein = 2.7 lbs protein

Oats + Grass Hay = 2.5 lbs protein

Omolene 200 + Grass Hay = 2.75 lbs protein

Oats + Alfalfa Hay = 3.85 lbs protein

Omolene 200 + Alfalfa Hay = 4.1 lbs protein

.25 pounds of protein difference between the 11.5% feed and the 14% feed, regardless of type of hay. Much bigger difference between hay types. Horse will not be burdened by the additional .25 pound of protein and, in some cases, may be helped.

Look at the total diet and consider both protein and calories:

NRC requirements

1100-pound mature horse, intense work = 2.9 lbs protein
                                                                                32,800 calories

14 lbs Oats + 20 lbs Grass Hay = 32,800 calories
                                                              3.41 lbs protein

10.5 lbs Om 200 + 20 lbs Grass Hay = 32,800 calories                                                                        3.27 lbs protein

10 lbs "10/10"* + 20 lbs Grass Hay = 32,800 calories
                                                                    2.85 lbs protein **

2-year-old in training = 2.46 lbs protein
                                          26,300 calories

12 lbs Oats + 15 lbs Grass Hay = 26,300 calories
                                                              2.72 lbs protein

9 lbs Om 200 + 15 lbs Grass Hay = 26,300 calories
                                                                 2.6 lbs protein

8.5 lbs "10/10"* + 15 lbs Grass Hay = 26,300 calories
                                                                     2.2 lbs protein**

                                              * 10% fat/10%protein feed
                                              ** falls short of protein requirement

In both of the above cases, Omolene 200 or Strategy would come closest to meeting the protein requirements without being excessive, and also take care of amino acid requirements. The "10/10" feed would fall short of protein requirements and would surely fall short of amino acid requirements. Exercising horses who are deficient in protein could suffer a variety of problems ranging from anemia to poor muscle tone, depending on the degree of deficiency, level of exercise and the length of time fed the deficiency.

If the above examples were done with alfalfa hay instead of grass, protein requirements would be exceeded by 35 to 40%. Obviously, if excess protein is a concern, a horseman would not feed straight alfalfa hay. If the hay causes protein to be that much too high, 2 -3% protein range in the grain wouldn’t even be noticed by the horse, other than to insure adequate amino acid intake.

Unless you add additional amino acids, such as lysine and threonine, to a 10% protein feed, the amino acid balance will be deficient for growing horses and probably most performance horses. This would be especially true with higher energy feeds, such as a 10% fat would be. Adding adequate amino acids is more expensive than simply increasing the protein to 12 or 14%.

Potential Problems from Excess Protein:

• Horse expends needed energy to metabolize and eliminate excess protein
• Excess protein is eliminated in the form of ammonia in the urine. Results in increased urination, therefore increasing water requirements. In a horse doing endurance type work, hydration is extremely important and difficult to maintain due to sweating and not being able to drink enough water. For other types of horses, drinking additional water results in wetter and often smellier stalls. There is some thought of risk of respiratory problems associated with this, but not documented. Increases cost of bedding stalls.

Potential Problems from Deficient Protein:

• Depressed appetite
• Poor hair coat
• Reduced hoof growth
• Slow, inefficient growth in young horses
• Anemia

It appears obvious that there is more to be concerned with in deficient protein diets than in excess protein in the diet.

Fat - Is more better?

More is not always better, sometimes it is just more. Fat is only one ingredient in a formulated feed. In order to achieve benefits from fat-added diets, it must be blended with adequate amounts of other necessary nutrients. Additional fat in the diet increases requirements for some nutrients such as Vitamin E and possibly B Vitamins. Also, adding fat changes the nutrient to calorie ratios, therefore, it may be necessary to increase the levels of all nutrients to insure adequate intake of all nutrients. Adding fat to a marginal diet doesn’t make it a high-performance diet. It just makes it a marginal diet with fat on it.

How much is enough?

We don’t really know the upper limit of fat for horses over long-term feeding conditions. More research needs to be done. As far as improving performance is concerned, we know we see improvements in performance from horses fed Omolene 200 or Strategy over other feeds. Could we get better performance with more fat? We are looking into that, but it is safe to say that it will probably depend much on other ingredients in the diet, total nutrient balance, type of exercise required by the performance and type of horse concerned. For instance, we may have reached the maximum performance improvement from adding fat for anaerobic performance horses (jumpers, reiners, cutters, quarter and TB race horses, etc.), as they use primarily glycogen during work. They use some fatty acids during warm-up and during performance, but the limiting factor for their performance is probably glycogen, not fat. For aerobic performers (endurance horses) there may be benefit to higher levels of fat, if all other requirements are being met as well.

We are striving for a level of performance, NOT a nutrient level on a tag.