Milk availability modulates weaning in the Norway rat (Rattus norvegicus).

Beginning on Day 14 postnatally, 368 Sprague-Dawley rat pups were exposed to different levels of milk supply by changing litter size of 10 dams from 8 to 4 or 12 (Exp I) or limiting temporally Ss' access to a lactating dam (1 of 36) to 8, 14, or 24 hrs/day (Exp II). Both manipulations accelerated weaning in milk-deprived Ss. By adding solid food and water to their diet, early weaning Ss compensated for the negative energy consequences of milk reduction and achieved premanipulation growth rates. Milk availability thus appears to affect weaning, and it is suggested that the developmental changes in the nutritive energy balance between mother and offspring contribute to the emergence of independent ingestion. (43 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)