Nitrogen utilization and metabolic responses of ponies to intense anaerobic exercise

Abstract

Summary Eight mature pony geldings with an average weight of 161 kg were randomly assigned to either control (no exercise) or treatment groups to examine the effects of intense anaerobic exercise on metabolic responses to treadmill exercise-tolerance tests and nitrogen utilization. Treated ponies pulled a weighted sled for 10 min/day, 5 day/wk for 6 weeks. Total weigh pulled ranged from 79 to 147 kg and was adjusted when necessary to maintain heart rates of 170 to 190 beats/min throughout each work session. All ponies were subjected to a 30 minute standard exercise-tolerance test on an equine tread-mill on Days 0, 21, and 42 of conditioning. There were no treatment differences in the metabolic parameters measured (heart rate, respiration rate, blood lactate concentration and rectal temperature). Six day nitrogen balance trials were conducted on both groups prior to conditioning and at Days 1 to 6 and 37 to 42 of conditioning. There were no significant treatment differences in fecal and urinary nitrogen excretion or nitrogen balance. Nitrogen intake was highly correlated with fecal and urinary nitrogen excretion, nitrogen balance, and nitrogen absorbed. It appears that nitrogen balance was affected more by nitrogen intake than by anaerobic exercise training.