ROLE OF THE NUTRITIONAL-STATUS OF THE LITTER AND LENGTH AND FREQUENCYOF MOTHER LITTER CONTACT BOUTS IN PROLONGING LACTATIONAL DIESTRUS IN RATS

Food restricting lactating rat dams over the first 2 weeks of lactatio n results in a prolongation of the period of lactational diestrus. Suc h food restriction has not only a direct effect on the dam but also th e pups are undernourished, and the pattern of dam-litter contact is al so changed. In a series of studies, we investigated the effects of nur sing undernourished pups and the change in dam-litter interaction on t he prolongation of lactational diestrus. While nursing undernourished pups in the last 2 weeks of lactation is sufficient to extend lactatio nal diestrus in ad Iib-fed dams nursing well-nourished pups in the las t 2 weeks of lactation is not necessary for the prolongation of lactat ional diestrus seen in food-restricted dams. Further, neither nursing underfed pups nor increased nest time in the first 2 weeks postpartum are necessary factors for the prolongation of lactational diestrus in food-restricted dams. (C) 1995 Academic Press, Inc.