Regulation of milk ingestion in the infant rat.
The aim of this study was to differentiate between maternal and offspring factors involved in the control of milk ingestion. Specifically, we investigated: (1) the temporal pattern of milk ingestion in fasted and non-fasted sucklings; (2) the amount of milk released as compared to that of milk available; and (3) the roles of the age of pups and the lactational stage of the dam as determinants of milk release. There were three general findings. First, the temporal pattern of milk letdown following a 5-hr accumulation consisted of an initial rapid phase followed by a slow "maintenance" phase. Second, a limiting factor in the amount of milk released is the dam's sensitivity to the suckling stimulus which changes as lactation progresses. Third, the age of the pups does not appear to play a determining role in milk release, but the degree of their deprivation does. In summary, it is suggested that compensation for weight loss during a fast in infant rats depends on an interplay between the pups' ability to increase their own intake, the milk availability, and the maternal sensitivity to suckling.
D000367:Age Factors; D000828:Animal Population Groups / Q000502:physiology*; D000818:Animals; D000833:Animals, Suckling / Q000502:physiology*; D001835:Body Weight; D005247:Feeding Behavior / Q000502:physiology*; D005260:Female; D005508:Food Deprivation / Q000502:physiology; D007774:Lactation; D011247:Pregnancy; D051381:Rats; D011919:Rats, Inbred Strains