Effects of frequent milking on milk secretion and mammary blood flow in the goat.

When goats were milked every hour for 8 h without the use of exogenous oxytocin, milk ejection each hour appeared to be more complete than had previously been reported. Moreover, the rate of milk secretion increased by 15% over the period of hourly milking. There were no major changes in the composition of the aqueous phase of milk. Mammary blood flow was not apparently changed when goats were milked hourly: there was no significant effect of time of day (between 09.00 and 17.00 h) on blood flow. These results are discussed in relation to the mechanism by which frequent milking increases the rate of milk secretion.