The effects of delays between restraint and sampling on some blood parameters in sheep

Twenty three non pregnant, non lactating aged Merino and Border Leicester ewes were subject to four jugular venipunctures one hour apart (times 0, 1, 2 and 3). Four different delay intervals of 12.5, 64.0, 128.0 and 252.9 seconds between catching and sampling (delays 1, 2, 3 and 4) were used on each sheep in a random manner. Estimates were made of packed cell volumes (PCVs), plasma and erythrocyte sodium and potassium concentrations. The mean PCV at time 0 of 35.4 per cent was significantly higher than the levels of 33.1, 31.8 and 32.2 per cent at times 1, 2 and 3 respectively. There was no significant difference between the means at times 1, 2 and 3. The mean plasma potassium concentrations at time 0 of 4.37 mmol/l was significantly higher than the levels of 4.16 and 4.14 mmol/l at times 1 and 3 respectively. Delays had no significant effects on the means of any of the parameters studied. The findings strongly suggest that sheep become excited by initial handling but not by subsequent venipunctures and that a delay between catching and sampling of between 12.5 and 252.9 second has no effect on the blood constituents studied.