The Effect of Removal of Residual Milk by Use of Oxytocin upon the Yield and Fat Content of Subsequent Milkings

Abstract

Summary During 5-day control periods, using six cows, the milk was removed from the udders in three approximately equal portions and each portion was weighed and tested. During experimental periods of the same length, the cows were milked in a similar manner, but in addition the residual milk was obtained by injection of oxytocin. It was found that normally drawn milk tested higher in all three portions when oxytocin had not been used at the previous milking than the corresponding portions when oxytocin had been used, indicating that the very high testing residual milk is secured with oxytocin at the expense of the fat content of the subsequent milking. This is interpreted as indicating that the residual milk is not static, but that most of it is secured under normal milking practices at the following milking. There is indication that a substantial part of the fat of milk secured under ordinary milking routine may regularly come from residual milk which was present in the gland at the time of the previous milking.