Effect of Interrupted Nursing on Lactation in Rats1

Interruption of suckling in rats for a single period of up to 12 hr in the immediate postpartum period or on day 10 of lactation had no significant effect on subsequent litter weights or mammary nucleic acid content. Interruption for 24 hr in both early and midlactation reduced litter weights and mammary gland RNA content but had no significant effect on weight of anterior pituitary, adrenal, or mammary gland DNA content. The results suggest that the effect of interrupted nursing is to reduce mammary gland metabolic activity without altering cell number and furthermore, that the effect probably occurs locally within the mammary gland.