Re: Horse too fast!!

[Tivers@aol.com]

In a message dated 2/18/99 4:50:13 AM Pacific Standard Time, qhll@eznet.net
writes:

<< Dear Tom:
         Many thanks for your prompt reply.  My memory is hazy, but I believe
 Kronfeld from UPA (20 years ago) said, 40 % as dry matter basis rather than
 % of energy.
         I am very intrigued by your mention of muscle fiber types.  It
 raises the q.: should horses with different muscle compositions get
 different diets?  Certainly horses vary by breed.  I would assume that dogs
 vary by breed.  Dog sledding is certainly an endurance activity.
 Quentin. >>

Yes. Sled dogs have almost 100% Fast Twitch High Oxidative muscle cells and
thrive on fat as their high energy fuel source. Lewis suggests that an
endurance horse will function at 95% aerobic energy production--which I think
is a little high, but in the ballpark--it ain't aerobic when you're going
uphill at a decent clip. 

In general, endurance horses carry around 60% FT and FTH cells while
racehorses will  demonstrat as high as 90% of the two fast-contracting cell
types. Now, because a cell has oxidative capacity and thus is able to burn
fat, it doesn't necessarily mean that fat is everything--most studies indicate
that fat contributes 40% of the muscular energy needed for endurance--and in
human sport, there is no stopping--you run the whole marathon at once. Still,
marathoners ingest carbohydrate/electrolyte drinks all along the way. In that
situation, as glycogen becomes depleted, then the body is forced to turn to
fat--or muscle protein--to support the work. That's why the carb
supplementation is used. 

ti