Milk accumulation and secretion in the rabbit

Over the 24 h period after suckling, total mammary-gland weight increased linearly indicating no reduction in the rate of milk secretion during the relatively long interval between sucklings in the rabbit. Thus, storage capacity is matched to the long storage period. Beyond 24 h in the absence of suckling at 24 h, the rate of milk accumulation declined rapidly. This decline was not prevented by the administration of ovine prolactin or by permitting suckling of sealed teats at 24 h. During the decline in secretory rate after 24 h, milk [Na] and [Cl] increased while [K] and [lactose] decreased, as in other species. It is concluded that the decrease in secretory rate after cessation of suckling is not caused by lack of hormonal stimulation; it is suggested that mammary distension caused by accumulation of milk is responsible.