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This is a long but very interesting article on feeding fats.

I am curious - Dr. G do you agree that a high fat diet still needs grains?
This article (from The Horse) mentions 100-mile endurance horses and the
need to continue feeding grains along with fats.

I was also not aware you needed to task the system on the "new fat" diet for
the body to begin using the fats as energy - very interesting article I
think.

Rusty

Excerpt from Revised Understanding Equine Nutrition: Fats[PARA]by: Karen
Briggs
November 20 2007, Article # 10848




Feeding Fats
If there's a nutritional buzzword for the 21st century, it's fat. We humans
still might not understand fully the differences between saturated and
unsaturated fats, let alone "good" cholesterol and "bad" cholesterol--but we
all know how to count our fat grams! While we struggle to keep our diets as
low-fat as possible, fat has a different focus when it comes to the horse...
because only in recent years have we recognized the value of raising the fat
levels in an equine athlete's diet.
Of course, the average human diet (at least in North America) contains far
more than the maximum 30% fat recommended for good health. In contrast, the
horse's natural diet contains almost no fat at all. Forages and fibers
contribute none, and most grains fed to horses only contain between 2% and
3.5% fat overall. While this leaves the horse at low risk for cardiovascular
clogging, it does mean that, traditionally, carbohydrates have been
considered the obvious and "natural" energy source for performance horses,
and fat has rarely been considered, beyond that little splash of corn oil
that's considered good for a shiny coat. Only in the last couple of decades
have we begun to realize that fat is also a valuable energy source -one with
many advantages.
High-fat diets (anything over and above the 2% to 3.5% supplied by a
standard grain-plus-forage diet) provide several perks, most notably in
terms of energy production for high-level equine performance. Pound for
pound, fat supplies almost two and a half times as much energy as the
equivalent weight of carbohydrates or starches (traditionally supplied by
grains such as oats, corn, or barley). If you wish to supply more energy to
your horse without significantly increasing his overall feed intake,
supplementing the fat in his diet can be an excellent way to accomplish
that.
Also, horses easily metabolize fat despite the fact that their digestive
systems (best adapted for the processing of fiber) didn't really evolve to
deal with it. Studies have shown that as much as 20% overall fat in the diet
is well tolerated by horses, with no ill effects noted. Indeed, fat might
well be easier for horses to digest than carbohydrates. It has been
demonstrated that a fat-supplemented diet, unlike a high-carbohydrate diet,
has no effect on the pH of the cecum (and thus no detrimental effect on the
beneficial microflora inhabiting the large intestine). Fat appears to be
absorbed almost exclusively in the small intestine.
Another interesting fat digestion fact is that horses can use fats well
despite the fact that they have no gall bladder. In most mammals the gall
bladder excretes bile and salts to help break down fats, but in horses the
liver seems to take over that function, with no fat digestion problems that
research has been able to identify.
Fat-supplemented diets also have been shown to decrease the amount of energy
used for heat production in the horse's body. This decreases the horse's
heat load and increases the amount of energy available for physical
activity. In one study, where horses ate a fat-supplemented diet, the
horse's total body heat production decreased by 14%, and the diet had no
effect on the amount of energy needed for maintenance metabolism, therefore
leaving more energy available for performance requirements (or for energy
storage in the form of glycogen or fat). The end result was that over 60%
more energy was available for physical activity (regardless of what the
ambient temperature was or how skinny or plump the horse was at the time).
Some of the most compelling research behind fat is that which demonstrates a
fat-supplemented diet's benefits for high-performance horses (in sports such
as three-day eventing, racing, polo, endurance racing, and cutting). But to
understand how fat acts as a performance enhancer, we first have to
understand some exercise physiology basics.
Dietary Fat for Athletic Performance
Grains, the "traditional" feed for high-level physical activity, supply
carbohydrates and starches--versatile energy substrates that fuel the
horse's muscles for athletic endeavors of all kinds. Fat is also an energy
substrate, which while not as flexible as carbohydrates in terms of the
types of activities it can fuel, might in many ways help the horse's body
use itself with more efficiency and less fatigue.
Two main energy pathways fuel a horse's muscle cells to do work. (A third
pathway, called "anaerobic alactic" metabolism, is a "start-up" system that
only comes into play for bursts of hundredths of a second.) The predominant
energy pathway is aerobic metabolism, which the muscles use whenever they
can, for all low-intensity and endurance activities, especially those
requiring a continuous effort of longer than two minutes (and possibly
lasting many hours). Blood glucose, derived from carbohydrates and starches
when they are broken down in the gut, is the main energy substrate for
aerobic metabolism, and muscle cells will draw on blood glucose as needed.
Oxygen, from the lungs, is the "fuel" used to burn the glucose in order to
produce ATP (adenosine triphosphate, the "energy molecule") along with the
non-toxic byproducts, water and carbon dioxide.
Blood glucose levels are regulated by insulin, which responds to high blood
glucose levels (as happens two to three hours after a high-carbohydrate
meal) by increasing and converting excess glucose to glycogen, the form in
which it is stored in muscle, fat, and liver cells. Another hormone,
glucagon, can reverse the process, converting glycogen back into glucose and
releasing it into the blood. This mechanism, while efficient, is not
foolproof--sometimes insulin might "spike" in response to a large load of
carbohydrates being introduced, causing large amounts of blood glucose to be
converted to glycogen and stored away. This can leave a horse hypoglycemic
(low in blood sugar) and feeling weak and fatigued.
As long as a horse stays below a certain performance threshold (which can
vary somewhat depending on the horse's activity, his conformation and muscle
bulk, and his degree of fitness), he can work aerobically. It's essentially
a "clean-burning" system that horses can maintain indefinitely, as long as
fuel continues to come in on a regular basis. Thus, it's the least taxing to
the system--but as blood glucose drops and as glycogen is drawn upon and
then depleted, fatigue can set in and force the horse's body to switch to
another energy pathway.
During high-intensity exercise of short duration, or when glycogen depletion
no longer allows a horse to work aerobically, his muscles will use anaerobic
lactic metabolism. "Sprint" type activities of about ten seconds to two
minutes in length are typical "anaerobic" activities; barrel racing is a
good example. When the aerobic system is working close to its full capacity,
the anaerobic system also will "kick in" like a supercharger, augmenting
rather than replacing the aerobic metabolism.
The anaerobic lactic system is entirely dependent on stored glycogen in the
muscles as an energy source. It is a far less efficient system than aerobic
metabolism in terms of the ATP produced per molecule of glycogen, and so it
depletes glycogen rapidly.
Here's where fat (finally!) comes in. Fat broken down in the digestive tract
becomes fatty acids--which can fuel aerobic metabolism but not anaerobic.
Adding fat to the diet provides a second source with which the body can
continue to work aerobically, delaying the switchover to anaerobic
metabolism, and thus postponing fatigue and performance deficits.
Studies have indicated that if the horse's system has supplemental levels of
fat available as an energy source, it can "learn" to use it in preference to
glycogen, thus increasing the amount of muscle glycogen the horse maintains.
That's good, because while glycogen stores in the body are limited, fat (in
the form of stored short-chain volatile fatty acids, or VFAs) is the most
abundant energy source in the body. Horses fed a high-fat diet also appear
to have better muscle glycogen utilization during anaerobic (sprint-type)
activities and no change in their blood glucose concentration (and thus
their insulin concentration) while working anaerobically. During aerobic
(endurance-type) activity, the same horses showed less decrease in their
blood glucose concentration than did horses fed a traditional grain diet,
and there was muscle glycogen sparing (less utilization of stored glycogen).
This glycogen sparing helps delay fatigue, an important factor in
performance enhancement. As a racing sage once observed, it isn't so much
which horse is going the fastest at the end of the race--it's more about
which horse is slowing down the least!
Pros and Cons
Horses fed high-fat diets (15% added soy oil) appear to perform better than
those fed either a high-starch diet (40%) or a high-protein (25%) diet for
both high-speed (racing) activities, and moderate-speed activities (fast
trot/slow canter speeds of about five meters a second). Their blood glucose
levels decreased less, and for a shorter duration, than did those horses on
high-carb diets. These benefits might produce only subtle results--but even
a gain of a few feet on a racetrack might result in a Derby win. Even at
lower levels of performance, the change can be valuable. For example, a
low-goal polo player might find that his horse can recover more quickly and
perhaps be able to play one more chukker, than before.
That's not to say that fat is a miracle ingredient. For reasons we don't yet
fully understand, the horse's body must "learn" to use fat as an energy
source, a process requiring considerable metabolic adaptation on the part of
the muscle cells. It can take three to four weeks, and the blood chemistry
might continue to adapt for up to six weeks. What this means is that you
can't just start feeding fat the day of the big race and see results. Not
only do you have to put your horse on the fat-supplemented diet a good month
in advance, but you also have to challenge his system so that it begins to
adapt. For a racehorse, that means you have to race him on the new diet, not
just train him conservatively, in order to help him begin to assimilate the
new energy source.
And as nice as it might be to contemplate improving further on the benefits
of feeding fat by feeding greater amounts--perhaps eliminating grain
altogether--unfortunately, it just doesn't work that way. Remember that only
carbohydrates can fuel the anaerobic system of metabolism, which all horses
use to some degree in their work--and that forages alone provide a minimum
of carbohydrate. (Fed by itself, forages provide plenty of fuel for
maintenance metabolism but not enough for the vast majority of horses to do
the work we ask.) Grain in the diet is an important fuel source for any
performance horse, and study after study has confirmed that high-fat diets
work best in conjunction with fairly high grain diets, for maximum benefit
in hard-working horses (such as 100-mile endurance racers, Thoroughbred and
Standardbred racehorses, and upper-level three-day-event horses). The
exception is horses with a genetic defect called equine polysaccharide
storage myopathy (PSSM), which have difficulty using carbohydrates as an
energy substrate; a prescribed diet in which fats almost completely replace
grains usually allows these horses to continue to perform.
So what level of fat is optimum for a performance benefit? That number is
still under some debate. Some researchers now recommend a level of 10% (by
weight) of the total daily diet for horses working at the extreme end of the
athletic spectrum, though slightly lower levels (about 8%) might be more
appropriate for horses working at a lower level of intensity. The level of
fat you choose might depend somewhat on the activity you're asking your
horse to perform. Some studies have indicated that levels up to 15% are
beneficial for horses involved in intense, long-term endurance activities
(chiefly competitive trail and endurance racing, and upper-level
three-day-eventing). However, even a level of 6% to 8% will result in some
performance benefit for horses involved in more moderate activity.
Feeding fat can also be well worth considering for reasons other than
performance enhancement--good news for the vast majority of us, who are
dealing with horses NOT at the cutting-edge of high performance.
First, it's true that supplemental levels of fat can enhance the quality and
shine of the hair coat, giving your horse a healthy glow that reflects
particularly well in the show ring. Supplemental fat can also help put or
keep weight on a "hard keeper," provided he is not in heavy work. Just as we
do (far too efficiently, sometimes!), horses will store excess fat in the
adipose tissues--so for plumping up a skinny horse, added fat is an
excellent solution that carries far less risk of stomach upset and other
complications than does a switch to a high-carbohydrate diet.
Older horses might benefit from a high-fat diet, too. As the condition of
their teeth starts to deteriorate and their digestive efficiency wanes,
easily digested fat can help prevent them from losing condition and becoming
ribby.
By the same token, broodmares can reap the rewards of added fat. Studies
have indicated that a mare that has recently "gained some condition" (easily
achieved by feeding added fat for a month or two before breeding) might
catch more easily and maintain her pregnancy with less difficulty. In
addition, a high fat diet can help her deal with the stress of lactation,
which can be considerable. A third perk is that her milk will be higher in
fat (mare's milk being fairly low to begin with), and as a result, her foal
will tend to gain weight and condition more easily.
Fat is often touted as an ingredient that provides energy without the
"hotness" that carbohydrates provide--so it is sometimes recommended in an
effort to calm a hot horse. Unfortunately, this one is a myth. As experts in
both human and equine research have noted, carbohydrates are falsely accused
of causing a "sugar high," and so substituting fat for a portion of the
grain being fed will make no difference to a horse's temperament or
attitude. The idea of horses getting "hot" from high-grain diets has more to
do with their being in hard training at the same time their grain ration is
increased, than it does with any physiological effects on a horse's manners.
As most trainers know, when you're exercising vigorously, you feel good and
you have more energy. The fact that you're getting more groceries is
coincidental.
How to Feed Fat
Adding fat to your horse's diet can be done in a number of ways. Practically
any digestible source of fat, either vegetable or animal, might be used. The
only source to avoid is the rumen-protectant variety of fat designed for
cattle, which horses will find at best indigestible and at worst, toxic.
(You won't run into this one unless you ask for it specifically at the feed
store.) It's interesting to note that horses actually can digest fat from
animal sources (such as tallow) very well, despite their vegetarian innards.
> From an economic standpoint, animal-fat products are generally much less
expensive than comparable vegetable fats or oils. But animal fats are seldom
used in horse rations for two reasons: First, they are usually solids at
room temperature, so they must be heated to liquid in order to mix with a
grain ration; and second, their palatability is generally low (try to get a
horse to eat something that smells like bacon grease!).
Of the vegetable sources of fats (which usually come in the form of oils),
corn and soy oil are traditional favorites, and readily available at most
feed mills as well as at many supermarkets. Other vegetable oils are just as
suitable, however, although many horse owners avoid canola oil as its
palatability isn't as good. Top-dressing your horse's grain ration with oil
is a simple process of measuring and pouring--but like any feed additive, it
should be introduced gradually, over a period of two to three weeks.
Other feed additives that are relatively high-fat, most notably rice bran,
have gained considerable popularity in parts of the United States. Rice bran
products, which come either as a powder or as an extruded pellet, are
approximately 22% fat, which means you have to feed considerably more of it
to get the same benefits as you would from a 100% fat product such as
vegetable oil. Rice bran has the advantage of being much more stable,
however, and is often preferred in warm, humid climates where oils and
animal fats tend to go rancid very quickly. Extruded soybeans, another
high-fat product, are good for young growing horses because they are also a
good protein source. for that same reason,they're not as appropriate for
mature animals. Then there's flax seed (30% fat), which because of its
omega-3 content (see sidebar) is an increasingly popular option, although
its small, hard seed coat means it needs to be processed immediately with a
coffee-grinder before feeding to make the fats available for digestion. Or
you can provide some extra fat with black-oil sunflower seeds (the unstriped
kind), which many horses relish as a treat. Sunflower seeds contain between
25% and 40% fat.
One of the simplest ways to add fat to your horse's diet is to choose a
commercial grain ration that is fat-supplemented. Many feed companies now
offer these products, usually as part of their premium line.
Fat-supplemented feeds are often equipped with extra anti-oxidants to
prevent spoilage, a management perk, and have camouflaged the fats with
other ingredients so there is no loss of palatability. Any feed that
contains more than about 3.5% fat is considered to be fat-supplemented. Look
for a crude fat level of 8% to 10% on the label (and if your horse is a
mature animal not being used for breeding, a protein content of 10% to 12%
at most), and introduce it gradually to your horse's diet. If your horse
objects to top-dressed oil or rice bran, a fat-supplemented sweetfeed or
pellet might be the best way to go.
Whatever way you decide to add fat to your horse's diet, you must consider
how it will affect the overall nutrient balance of his daily ration. If you
add fat to your horse's routine but don't increase his exercise level or cut
down on his grain, he's likely to get fat. However, if you cut back on your
horse's grain, you also reduce the concentration of vitamins and minerals he
receives. In contrast to other feeds, oils contribute no incidental nutrient
value--that is, they contain no protein, calcium, phosphorus, or any other
nutrients to speak of beyond the fat calories, though other fat sources such
as rice bran are sometimes supplemented. For this reason, it's important to
work with an equine nutritionist (whom you can contact through your feed
dealer, local veterinary college, or state extension service) to help you
make the necessary adjustments so that your horse doesn't get cheated out of
essential vitamins and minerals. You might have to consider adding a
supplement to compensate for these losses.
If you're feeding a commercial ration that is a "premium" product, you might
not have to worry about deficiencies of vitamins and minerals as many of
these are deliberately designed with an excess of most nutrients. And if you
decide to go with an all-inclusive high-fat feed, the feed company has
likely already done the ration balancing for you. Consult with your equine
nutritionist to be sure.
One thing fat is not going to do is make feeding any cheaper. Pound for
pound, it usually works out to be nearly as expensive, if not a little more
so, than a comparable quantity of carbohydrates. Is it cost-effective?
That's hard to say. But as one researcher points out--if you can move a
racehorse up six feet in a mile and a half, it doesn't really matter what it
costs, does it?



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