Hiya,
Somewhere back in the archives is a more detailed explanation of why,
but basically, I don't recommend feeding any sort of grain or processed
grain product (which would include Equine Senior) less than six hours of
so before the start of a ride. Hay SHOULD be fed free choice, as it
maintains gut motility and provides a reservoir of water and
electrolytes in the gut.
Any sort of highly soluble carbohydrates, to one extent or another,
however, are broken down fairly quickly in the stomach and small
intestine and absorbed as simple sugars into the bloodstream, where they
quickly raise blood glucose levels. This, in and of itself, isn't a bad
thing, except that most riders don't need any additional rocket fuel at
the beginning of the race.
However, the elevated blood glucose will immediately trigger a large
release of insulin, the pancreatic hormone which helps remove glucose
from the blood and pack it away into storage as glycogen and fat. Keep
in mind that at the same time that insulin is removing glucose from the
blood, you're trotting along, and also expending glucose through
exercise. Blood glucose levels drop sharply and rather than having more
glucose available from having fed grain, you actually have LESS
available in the blood. Not what you want considering the miles you
have to travel that day.
In addition, insulin has an inhibiting effect on beta-oxidation, the
burning of fats for energy. Fats are the primary source of energy for
sub-maximal exercise such as endurance, and the last thing you want to
do is do anything to slow down that metabolic pathway.
Bottom line, feeding grains semi-immediately before a ride is going to
result in high glucose and energy at the start (when you don't need it)
and reduced energy production later on down the road (when you do need
it).
This isn't the only school of thought on feeding endurance horses before
a ride, but it's pretty much the accepted one among equine exercise
physiologists. Theoretically, you could maintain relatively high
glucose levels if you could supply a continual stream of soluble carbos
throughout the day, but doing so also has a tendency to affect the
acid-base balance of the hindgut, which can also be detrimental.
Without sounding melodramatic, sometimes extremely detrimental.
There have been some pretty exhaustive discussions on beet pulp lately,
so I won't go into those yet again, except to say that in addition to
feeding hay (and, as Gayle pointed out the other day, wet hay is even
better) at every opportunity, I like feeding SOAKED beet pulp because it
provides additional energy without causing the glucose/insulin spikes
that more soluble carbohydrates do. You might consider trying your
horse on some beet pulp during rides in place of pre-processed feeds and
see how he does.
Regarding processed feeds specifically, Dr. Sarah Ralston at Rutgers did
a nifty study on glycemic/insulin response in ponies that were fed
highly soluble carbohydrtaes pellets vs a low soluble carbohydrate
pellet (and thanks for sending it to me, Dr. Ralston! :-). The
responses found were more or less as described above (soluble carbos
produce a higher glucose/insulin spike) but the differences weren't as
dramatic as would be expected. Because the carbohydrates portion of the
ration was in a pelleted form, it was suggested that possibly simply
processing the feed into pellets makes the carbohydrates more available,
thus producing the higher glucose/insulin response.
So, I would suspect that even though Equine Senior contains a
substantial proportion of hay, it may overall behave more like a soluble
carbohydrate than it would if the roughage portion were provided in
regular flake hay form. As a result, the pellets MIGHT be more likely
to produce glucose/insulin responses that you really don't want. My
suggestion would be to provide a moderate (not "extra") meal of his
Equine Senior pellets the night before (this "fills the gas tanks" while
the attendent glucose/insulin effects occur while the horse is just
standing around, not exercising). Also provide free-choice hay all
night to maintain gut motility during the ride. During the ride itself,
provide soaked beet pulp, mixed with SOME, not a ton of, Eq Senior
pellets throughout the day, along with wet hay. After the ride, provide
plenty of hay and only pellets after he's well recovered and has good
gut sounds, and even then, don't overdo the grains.
Hope this helps,
Susan Garlinghouse