The influence of diets deficient in energy, or in protein, on conceptus weight, and the placental transfer of a non-metabolisable amino acid in the guinea pig.

The effect on the guinea pig conceptus of feeding the mother diets deficient in energy or in protein has been investigated. Fetal uptake of a labelled non-metabolisable amino acid, amino-isobutyric acid, injected into the maternal blood stream, was studied at the end of gestation. Both diets retarded fetal growth, influencing litter number and fetal and placental weight. The relationship between fetal and placental weight was similar in the control and restricted-calorie animals, and the transfer studies showed that placental function and fetal uptake per unit weight was similar in the two. Feeding a low-protein diet caused the ratio between fetal and placental weight to increase; enhanced placental transfer and fetal uptake also suggested the possibility of adaptation when the calorie supply is adequate.