Investigation and Application of Methods for Measuring Energy Expenditure Rate and Selected Physiological Changes Due to Exercise in Horses

120 p.Thesis (Ph.D.)--University of Illinois at Urbana-Champaign, 1980.The research for this dissertation had three major objectives: (1) to evaluate certain physiological parameters adapted from studies on human athletes in measuring selected physiological changes due to exercise in horses, (2) to accurately determine and factor the energy expenditure rate during physical work in horses, and (3) to apply these physiological parameters during racing and conditioning in horses.I. Methods for Measuring Energy Expenditure Rate and Physiological Changes Due to Exercise in Horses. (A) Two pony foals were placed in a metabolism chamber for indirect calorimetric measurement of standard metabolic rate (SMR) and the energy expenditure rate of standing-fed subjects. Determined SMR approached calculated SMR using metabolic body weight (kg('.75)). The increase in energy expenditure rate for a standing-fed subject over SMR averaged 149 percent. (B) Two two-year-old pony geldings were used to evaluate methods for collection of respiratory gas samples, heart rates and muscle lactic acid concentrations on exercising equines. A specially designed face mask afforded energy expenditure rates on exercising animals that approached corresponding values obtained in the metabolism chamber and NRC (1978) estimations for exercising animals. Energy expenditure rate increased by 3.21 kcal hr('-1) kg('-1) for walking over standing and 4.53 kcal hr('-1) kg('-1) for trotting over standing. Respiratory quotients tended to decrease due to training, during long term submaximal exercise and remained low during recovery. Heart rate recovery measured with a single-channel electrocardiograph tended to increase due to training. Muscle lactic acid concentrations increased during bouts of walking but decreased during bouts of trotting.II. Effect of Training Method - Walker, Riding or Treadmill on Selected Physiological Parameters in the Yearling Quarter Horse. Six yearling Quarter Horses were used to compare to effects of three popular training methods on conditioning and efficiency of performing approximately equal amounts of work. All horses carried 63.5 kg of weight.Riding horses had lower mean after-exercise heart rates than the other methods. Heart rate was increased on all methods for all exercise bouts. Respiratory quotients tended to decrease due to training, during exercises investigated and remained low during recovery. Energy expenditure rate was higher and corrected partial efficiency of work lower for riding horses than for treadmill and walker horses after 10 to 15 minutes of trotting.III. Effects of Training, Racing and Diet on Selected Physiological Parameters in Two-and Three-Year Old Quarter Horses. The two-year old and two three-year old Quarter Horse fillies were used in a two year replication of a simple reversal study. One filly of each age was fed either corn or oats, plus hay. Diets were formulated to be isocaloric and isonitrogenous as fed. The fillies were trained on the diets, match raced once a week for four weeks, then the diets were reversed for 30 days and the fillies were again match raced once a week for four weeks.Mean energy expenditure rate increased 3.4 times and mean heart rate increased 2.3 times over values at rest after a 348 m race. Resting heart rate and respiratory quotient tended to decrease due to training. A significant linear effect of age, race, diet sequence and age x race interaction was observed on after race RQ. A significant linear effect of age was observed on after-race heart rate. A significant linear effect of age, race, diet sequence and race x diet sequence on racing time was also observed. The change in muscle lactic acid concentration over resting after the race was greater in the reversal series of races than in the initial series.U of I OnlyRestricted to the U of I community idenfinitely during batch ingest of legacy ETD