Asia Pacific Journal of Clinical Nutrition (2002) 11 (Suppl)S274 Comparative changes in glycogen concentrations after exercise in muscle, liver, kidney, skin and duodenum of sheep

Little is known about the repletion of glycogen after exercise in tissues of ruminants other than muscle. Skeletal muscle is the major consumer of glucose in the body (1) and stores glycogen for its own use. Glycogen concentration of muscle is an important determinant of ultimate pH and eating quality of meat (2). However ruminants rely on gluconeogenesis in the liver and to a lesser extent the kidney to supply most of their glucose needs. Anaerobic exercise causes depletion of muscle and liver glycogen and has been used to model the effects of stress on muscle glycogen concentration (3). The aim of this experiment was to compare glycogen concentrations in a range of tissues before and after exercise and at a number of time intervals after exercise. 105 merino wethers that had a mean liveweight of 42.5 kg and had been shorn 3 months previously were used for the experiment. The exercise protocol consisted of running the sheep 4 times around a 2 kilometre track with a 15-minute rest interval between each run (Gardner et al., 2001). Groups of sheep were slaughtered before and after exercise then at 12 hours, 24 hours and 48 hours after exercise. Each plot was replicated 3 times and contained 4 sheep for the pre and post exercise periods, and 3 sheep for the 12 hour, 24 hour and 48 hour post exercise periods. A pelleted diet was used for the experiment that contained lupin seed (25%), cereal hay (35%), barley grain (35%), bentonite (2%), sodium bicarbonate (0.7%), salt (0.5%), dicalcium phosphate (0.1%), vitamin mineral mixture (0.1%), and Bovatec50 TM (0.02%). The pellets contained 12.2 MJ/kg metabolisable energy (ME) and 12.7 % crude protein on a dry matter (DM) basis. Prior to exercise sheep were fe