Energy/protein interrelation in experimental food restriction.

The effects of restriction of energy and/or protein intake were studied in rats during pregnancy and lactation and in adult mice. Three approaches were employed: sucrose stimulus-induced reduction in the intake of an adequate diet given simultaneously; restriction of intake of a complete food by 30% of ad libitum levels and selective protein or energy restriction of a high protein diet and a non-protein diet. Casein or lactalbumin was the protein source. During lactation the rat's natural food intake regulatory mechanism prevailed over the sucrose stimulus. Restricted intake of the complete food and selective restriction of protein or energy, variably influenced gestational and lactational performance and weight of young at weaning. A distinct regulation in the intake of protein and energy during pregnancy and lactation was observed on selective energy or protein restriction. Restricted feeding of the composite diet starting in the second year of life, to mice previously ad libitum fed a lab chow of constant composition, promoted the highest survival rate.