Re: Carbs - only part of the picture

[Tivers@aol.com]

For those of you who are enthralled with the older nutrition science, a couple
of quotes from Lon Lewis' "Feeding and Care of the Horse":

"Crude fiber is primarily celluose. It is the most poorly utilized source of
energy. Much of the crude fiber ingested is excreted in the feces. Thus, the
higher the fiber content of the feed, the lower the amount of energy that feed
will provide, and the poorer the quality of the feed."

Lewis suggests that a horse working at a fast trot and cantering requires .29
lbs of Total Digestible Nutrient per 100 lbs body weight per hour, with hay at
41% TDN. A 900 lb horse, then, should be consuming 2.7 lbs of TDN per hour. If
that was strictly hay, then in 6 hours the horse should consume 36 lbs of hay.
If fed strictly grain or a grain mix, then the TDN would hover around 75% and
the horse should consume about 19 lbs of grain in those six hours. If you fed
half that amount of hay, and half that amount of grain, by weight, you'd be
short about 5-6 lbs of grain. Thus, 18lbs of hay and 13-14 lbs of grain should
sustain a 900lb horse for 6 hours of strenuous trotting or cantering. Lewis
suggests that the ratio should be nearer to 50% hay, 50% grain. So, 15 lbs of
each might be appropriate for 6 hours of reasonably strenuous work.

At a slow trot, the horse requires .12 lbs of TDN per hour per 100 lbs body
weight. So a 900 lb horse working very slowly for 6 hours requires 6.48 lbs of
TDN. That would be about 14 lbs of hay or something in the neighborhood of 9
lbs of grain. 

Lewis also states that carbohydrates are digested in the stomach and that this
digesta passes into the small intestine where carbohydrate (50%) digestion
continues and proteins and other nutrients digested and absorbed. Most
feedstuffs leave the stomach (2-3 gallon capacity) within 30 minutes. 

Lewis, in 1981, had no data concerning the near 100% digestibility and
carbohydrate content of glycogen loaders.    Lewis cites 109 references. 

ti