Feeding Horses for Weight Change
By Dr. Chuck Sasse
When horse owners are looking for their horse to either gain or lose weight, most do not know how much to change the amount of daily feed to achieve the desired condition.
Following are some of the most important considerations and guidelines to help your horse gain or lose the weight you want in the time frame you have. Or maybe you will discover that your goal is unrealistic. How important is calorie counting, activity levels, horse weight, hay quality, or stage of maturity of pasture? How safe are high intakes of grain mixes and are their differences among feeds?
For this article, the applications discussed apply to mature healthy horses. Young growing horses will be more efficient and eat more per unit bodyweight. Sick horses will vary tremendously in weight loss or gain depending on the type, severity and stage of disease.
In the healthy mature horse, the nutrient needs for protein, minerals, and vitamins can be met by 3-4 Ib/day of a quality commercial grain mix or 1-2 Ib/day of a commercial concentrate along with sufficient quantity and quality of hay. These needs may also be met for a couple months in the spring by good pasture. A horse that is receiving these daily minimums and is healthy is not likely to respond to adjustments such as the additions of feed supplements, but is going to change weight due to the total calories consumed for the weight and activity level of the horse. Therefore, calories are the focus when a change in weight is desired.
There is at least a three-fold difference in the number of calories a horse requires to maintain a constant body weight (maintenance) depending on the size/weight and the work/activity level of the horse. Table 1 shows the daily energy needs in kcal/lb for 800,1000, and 1200 Ib horses at three activity levels ranging from maintenance such as stalled with little exercise to moderate performance work such as an hour or more per day of exerting more effort than walking. It is immediately obvious that there are dramatic differences in the calories it takes to hold weight constant on different horses. That is why consultants always ask several questions about the horse before giving any feeding recommendations. The 800 Ib horse at maintenance needs 12,800 kcal/day to hold weight with minimal work, whereas the 1200 Ib horse at moderate work needs 28,800 kcal/day to maintain weight. At maintenance activity a horse can frequently hold weight or even gain a little with good quality hay or pasture, but not so for moderate work. For a horse at moderate work, it cannot eat enough pounds of hay to hold weight, so it must eat part of its diet in a more energy dense form, such as a grain mix.
TABLE 1 - Energy Needs (kcal/day to Maintain Weight Activity/Work Level
Horse Wt. Maintenance Light Moderate (kcal/day
800 12,800 16,000 19,200 1000 16,000 20,000 24,000 1200 19,200 24,000 28,800
So to determine first how much of what feedstuffs it takes to hold weight constant, one must know the energy (kcal/lb) in the products available to feed. Table 2 lists the energy content of common commodities used in the area. If you are interested in energy values of Purina Horse Feeds, contact your Gold Dealer of Purina District Rep. It is important to realize that hay is a necessary part of the horse diet which is provided in the commercial feed sometimes as in the Equine Senior, Adult and Junior, Complete Advantage and the Horse Chows, or as baled or cubed product fed separately.
However, nearly all grains and grain mixes contain at least 50% more energy/lb than grass hay. Top commercial grain mixes such as Strategy and the Omolene products may contain twice the energy/lb as the hay fed (Purina's Strategy will have 25-30% more calories than oats.) Also, it is important to
notice the difference in energy/lb between midbloom and mature brome hay. The protein drops from about 12% for midbloom to 5-6% for mature brome. To have top quality brome hay in this area it must be baled by mid-June most years.
TABLE 2 - Energy Content of Common Feeds Feed kcal/lb Oats 1200
Brome hay - midbloom 850 Brome hay - mature 700 Alfalfa 900 Molasses 1080 Corn 1600 Fat 3600
Using the numbers from above and some common sense, feeding programs can be established for maintaining a horse at constant weight. But what else is needed to determine a program for gaining or losing one pound/day, for example? How many calories does it take? Well, that depends on several things, but the most important in a healthy mature horse is the composition of that gain or loss. Short- term, the fill or amount of food in the digestive tract, or the tissue water retention or dehydration can be significant factors in weight change, but the desire is for long-term condition change. A horse that is very thin, been sick, or for other reasons is going to gain muscle mass may be far more efficient for a relatively short time than a horse in good condition that is changing the amount of fat (condition score). Fat has about 2 Y4 times the energy/lb of protein, glycogen or sugar and therefore, requires over twice the calories to gain a pound of fat. But most of the time in our horses, the gain or loss desired is simply a gain or loss of the fat covering the ribs, along the backbone and tail head, and through the shoulder and neck area-area evaluated in condition scoring.
The assumption is made for the following calculations that the horse is in good enough condition that muscle gain is not occurring and the gain or loss is fat! For the mature healthy horse to gain a Ib/day of fat requires about 6000 kcal/day above the energy needed to maintain the horse at constant weight. That requires about 4 extra Ib/day of Strategy, 5 extra Ib/day of oats or 7.5 Ib/day of average brome hay. To lose a Ib/day of fat requires that the total energy/day be reduced by a similar amount from maintenance. If a horse is gaining alb/day and you wish for it to lose a Ib/day, the total energy/day must be reduced by about 12,000 kcal/day. Such a scenario may require limiting the hay a little and using 1
Ib/day of a horse concentrate, like Horse Charge which has no grain or added fat but meets the protein, mineral and vitamin needs.
When adding weight to horses, a constant concern is the safety of using high levels of grain mixes in horses. Horse owners are rightfully concerned about founder and colic with increased grain intake.
Most of the energy in grain is in the form of starch which is digested into sugar and absorbed into the bloodstream. The horse is designed to eat roughages and does not handle high sugar levels as well as species like pigs and chickens. So feeding schemes for horses must be managed more carefully. Sweet feeds require the greatest care because most of the energy is from starch and the sugar in molasses. Most of the energy made available to the bloodstream of the horse from fiber is in the form of volatile fatty acids and have minimal effect on blood sugar levels. Fat in the feed is partially digested and absorbed independent of sugar and starch and has no influence on blood sugar levels.
One of the primary ways to manage elevated levels of grain mix in the diet is to control feeding frequency and size of meal. The horse's stomach is quite small for its body weight and empties rapidly, which has both positive and negative aspects. The positive is that a feeding is eaten and digested quickly and the effect of that meal on the bloodstream levels of metabolites such as sugar are relatively short-lived. This allows for feeding the horse several times a day and largely escaping the effects of the meal.
So if a horse needs to have 12-15 Ib/day of grain mix it is safer to break that into 3 feedings of 4-5 Ib/meal. Even with this scheme it is necessary to gradually increase the pounds per feeding by about % Ib every couple of days.
There are very marked differences from horse to horse at about the same weight and activity level in the calories needed per day. These differences are often related to genetic differences, age, disease past or current, dental health and/or apparent differences due to hay quality. The differences make it very important to know the approximate calories needed by your own horse for maintenance so you can calculate the adjustment needed to gain or lose weight and condition.
In summary, larger than generally expected changes in feeding levels are needed to gain or lose appreciable weight. It requires a change of about 4-5 Ib/day in grain mix to change weight 1 Ib/day assuming the loss or gain is fat. When increasing grain mix, do it gradually and add more feedings/day to avoid feeding more than 4-5 Ib/meal. Calories from fat and fiber are safer since they do no contribute to blood sugar from digestion.
For more details, to ask questions or to apply these principles to your situation, call or visit me at Lloyd's Dog and Horse at 1030 Santa Fe in Olathe, KS (913-764-4626),
