Effectiveness of Subcutaneously Administered Oxytocin upon Removal of Residual Milk

Abstract

Oxytocin was injected subcutaneously into 16 dairy cattle at a level of 20 IU immediately after the pm milking, to obtain residual milk. Intervals of 5, 10, 15, and 20 minutes from injection to harvesting residual milk were tested each for one week on alternate weeks over an eight-week period. Milking time for residual milk was standardized to five minutes. The amount of residual milk and per cent residual milk of normal pm milk increased significantly when delay times of ten minutes or longer were compared to a five-minute delay. Mean per cent residual milk for 16 cows based on six-day averages was 16.8%. Per cent residual milk was higher in low producers than in medium producers, but the percentages within each group increased as the level of production increased. Variations in per cent residual milk showed a skewed distribution, with some cows having as high as 68% residual milk. Milk fat per cent increased in residual milk, but not as much in low producers as in medium producers. Oxytocin treatment to remove residual milk did not result in decreased production at the succeeding am milking.