Changes in diet and patterns of feeding activity of developing rats
Redman, R.S.; Sweney, L.R.
Journal of Nutrition 106(5): 615-626
1976
ISSN/ISBN: 0022-3166 PMID: 1262970 Document Number: 101685
Estimations were made of the amount of milk and stock diet eaten by Sprague-Dawley rats during postnatal development and the extent to which they fed in circadian rhythms when weaned by their mothers or artificially at 21 days old. An approach used in 3 experiments was to weigh feed bins at circadian intervals. The second approach was to analyse the stomach contents of rats killed at intervals during 24 h. The stomach contents were inspected, freeze-dried, weighed and chemically analysed for fat. The difference in fat content between rat milk solids and stock diet was the basis for estimating proportions of stock diet and milk. The results indicated that natural weaning occurred progressively from 14 to 30 days of life, with an accelerated phase between 18 and 25 days; the young up to 8 days old and their mothers fed mostly in light and darkness, respectively; circadian variations in feeding were weak and inconsistent in the young 10 to 20 days old and their mothers; at 21 days old the young and their mothers began to feed mostly in the dark; the proportions of food eaten in light and darkness approached those of the adult by the age of 29 days when rats were weaned naturally and by 25 days when weaned at 21 days; and progression into the nocturnal feeding pattern might be disturbed if larger litters were not provided with sufficient space.