The effect of food restriction by time-scheduled feeding on the development of body-weight, lifespan and incidence of spontaneous tumours and diseases in male Han:SPRD rats.

Abstract

Food consumption, development of body weight, lifespan and incidence of spontaneous diseases and tumours were investigated in 3 groups of 96 male Han:SPRD rats each maintained in a longevity study from weaning up to their natural death. All rats were fed a commercial cereal-based diet. One group received food ad libitum and was used as control group. Access to the diet was controlled in the other two groups by means of an automatic timer. The rats of one of the latter groups were fed nocturnally (4 x 42 min daily during the dark period) and those of the other adiurnally (4 x 42 min daily, each two times during dark and light period). Time-scheduled feeding caused an evident food restriction compared with the food consumption of the rats fed ad libitum. This food restriction, however, was significantly more pronounced in the younger animals during the first weeks after weaning than in the older rats. The body weight development corresponded to the feed intake. In animals subjected to food restriction the weight remained below that of rats fed ad libitum during all age periods. Furthermore, time-scheduled feeding caused an important increase of the mean life expectancy and a reduction in the incidences of chronic nephropathy and purulent and chronic forms of prostatitis. Only a slight effect of controlled feeding was observed on the incidence of alveolar lipoproteinosis. Time-scheduled feeding did not cause a reduction in the incidence of tumours, but it delayed their occurrence. The risk to develop various types of tumours during the third year of life was significantly higher in the ad libitum group than in the rats fed by a controlled regime. The automaton Han:CHRONOFEEDER, used in this study, has proved to be an appropriate, relatively inexpensive and easily installable feeding system for automatic control of food accessibility. It is suitable to implement controlled feeding and food restriction of rodents in longterm experiments.