AJP - Regulatory, Integrative and Comparative Physiology, Vol 246, Issue 1 96-101, Copyright © 1984 by American Physiological Society
Role of dietary preferences in the weaning pattern of the rat
H. H. Blake, C. T. Okuhara and S. J. Henning
Weaning in the rat begins on postnatal day 17 and is completed by day 26.
To evaluate the contribution of dietary preferences and/or aversions to
weaning progression, choice experiments utilizing isocaloric liquid diets
were conducted. In experiment 1, both consumption records and behavioral
studies showed that pups choosing between two diets differing only in the
nature of the carbohydrate (CHO) (glucose vs. lactose) had a strong
preference for the glucose diet. In experiment 2, pups chose between diets
differing in the relative proportions of CHO and fat. When the CHO was
glucose, the preference was for the high-CHO diet, whereas when the CHO was
lactose, the preference was for the low-CHO diet. The sweetness preference
and/or lactose aversion of these experiments was present from day 17 onward
and therefore cannot explain the gradual transition seen in normal weaning.
In experiment 3, behavioral testing showed that pups choosing between
suckling from their anesthetized dam or drinking a liquid diet strongly
preferred to suckle at day 17 but to drink by day 24. The gradual
transition displayed in this experiment suggests that the decline of
interest in suckling plays an important role in the process of weaning.
