Exercise in Merino sheep - the relationships between work intensity, endurance, anaerobic threshold and glucose metabolism
1991
Pethick, D.W. | Miller, C.B. | Harman, N.G. (Murdoch Univ. (Australia). Div. of Veterinary Biology)
Merino ewes were cannulated to study the splanchnic tissues at rest or during each of 8 levels of exercise, defined as km per hour at either 0 or 9 degrees incline. Only exercise well in excess of the anaerobic threshold resulted in ewes showing fatigue. Fatigue was not associated with carbohydrate depletion or lacticacidosis; changes in the CO2 content and pH of blood suggest that thermoregulation is an important component of fatigue. Above the anaerobic threshold, splanchnic blood flow declined, and a pronounced hyperglycaemia occurred. The release of glucose by the liver was consistent with an exaggerated response due to "feed forward" control. The contribution of lactate and glycerol to gluconeogenesis declined only at the highest work load. The requirement for gluconeogenic end products of digestion for animals grazed under extensive conditions would be from 9 to 30 percent greater than for animals not exercising, depending on the intensity of the exercise.
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