Journal of Applied Physiology, Vol 68, Issue 4 1399-1404, Copyright © 1990 by American Physiological Society
Changes in the metabolic profile of equine muscle from birth through 1 yr of age
K. H. Kline and P. J. Bechtel
Department of Animal Sciences, University of Illinois, Urbana 61801.
The purpose of this study was to investigate metabolic changes in equine
muscle from birth to 1 yr of age. Duplicate biopsies from the middle
portion of the gluteus medius were obtained from a depth of 2 cm beneath
the superficial fascia at 1 day, 7 days, 1 mo, 3 mo, 6 mo, and 1 yr of age
in 11 quarter horses and at 1 day, 3 mo, 6 mo, and 1 yr of age in 5
Standardbreds. Muscle enzyme activities determined were citrate synthase,
3-hydroxyacyl-CoA dehydrogenase, phosphorylase, and lactate dehydrogenase.
Percent fast-twitch, fast-twitch high oxidative, and slow-twitch oxidative
fiber types were determined using succinate dehydrogenase and myosin
adenosinetriphosphatase (pH 9.4) histochemical stains. Histochemically
determined muscle fiber-type percents did not change dramatically with
increasing age. However, lactate dehydrogenase activity increased threefold
in quarter horses and twofold in Standardbreds, and phosphorylase activity
increased sixfold in quarter horses and sevenfold in Standardbreds from 1
day to 6 mo of age. Citrate synthase and 3-hydroxyacyl-CoA dehydrogenase
activities decreased during the first 3 mo of age in quarter horses.
