[The development of the regulation of food intake during ontogenesis--the effect of hyperalimentation on body weight gain in suckling rats].

In an experiment, the number of young rats per nest was reduced to two in time intervals from the 1st to the 6th, from the 6th to the 11th, from the 11th to the 16th, and from the 16th to the 21st day after birth (groups P1, P2, P3 and P4 respectively). The plenty of milk available to the young for a period of five days positively influenced the body weight of the rats in group P2, whereas in the remaining groups the total weight showed no significant change in comparison with normally fed animals. The subsequent normalization of nutrition in the test young (the number of the young in nests was increased to eight) induced a decrease in weight gains in the older test animals (groups P3, P4), whereas in the 6- to 11-day-old rats (P2) the higher weight gains were retained in the next growth stages. The results give evidence that an external interference in the nutrition of rats (hyperalimentation) in the period from the 6th to the 11th day of life can influence, for a longer time, feeding behaviour and weight gains. The relative stability of the body weight of the young after the 11th day of life suggests to the functional involvement of the regulatory mechanisms controlling feed intake in this period of life.