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Title:Nitrogen Metabolites During Exercise in the Horse
Author(s):Miller-Graber, Peggy Ann
Doctoral Committee Chair(s):Lawrence, Laurie,
Department / Program:Animal Science
Discipline:Animal Science
Degree Granting Institution:University of Illinois at Urbana-Champaign
Subject(s):Agriculture, Animal Culture and Nutrition
Abstract:In experiment one, eight Quarter Horse mares were intravenously infused prior to exercise with either sodium acetate (control) or ammonium acetate to determine the effect of elevated ammonia (NH$\sb3$) levels on fatigue development and muscle metabolism. The horses were exercised on an 11% grade treadmill at 4.4 m/s, carrying 27 kg of lead. Time to fatigue was not (P $>$.05) different between groups. Middle gluteal muscle (im) NH$\sb3$ and lactate increased (P $$.05). Treatment did not (P $>$.05) affect plasma or im ala, glu or gln. Urinary orotic acid/creatinine ratio was not (P $>$.05) affected by exercise or treatment and suggests that the urea cycle was not impaired during exercise. These results did not show any metabolic evidence for a role of increased blood NH$\sb3$ in fatigue development at the level of the central nervous system.
In a second experiment, six mature Quarter Horse mares were used in a crossover design to assess the effect of dietary protein level on energy and nitrogen metabolism during exercise. After a 2-wk adaptation to either a 9.0% (control) or an 18.5% crude protein (high-protein: HP) diet, each mare performed an exercise test (ET). The ET was performed in the absorptive stage of digestion and consisted of a 15 min exercise period at 4.5 m/s on an 11% grade treadmill. The dietary treatment did not (P $>$.05) affect heart rate or oxygen uptake; however, exercise resulted in an increase (P $$.05) effects due to treatment. A diet by exercise interaction (P $<$.01) occurred for plasma ala, being lower in the HP horses. Plasma urea-N, the urinary urea-N/creatinine and orotic acid/creatinine ratio were higher (P $<$.001) in the HP group. The excretion of urea-N in sweat was also higher (P $<$.001) in the HP group. Substrate utilization during exercise was not altered by excess dietary protein; however, excess protein stimulated nitrogen metabolism in the horse at rest, during submaximal exercise and during recovery.
Issue Date:1988
Description:239 p.
Thesis (Ph.D.)--University of Illinois at Urbana-Champaign, 1988.
Other Identifier(s):(UMI)AAI8908780
Date Available in IDEALS:2014-12-15
Date Deposited:1988

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