Influence of maternal dietary protein and fat levels on fetal growth in mice.

The influence of maternal dietary fat and protein levels during gestation on fetal growth was determined in LAF1/J mice. Dams were fed diets containing various levels of casein (ranging from 6 to 20%) and fat (either 5 or 15%). On the 18th day of gestation, all animals were sacrificed. Products of conception were examined, and maternal liver and fetal body compositional analysis was performed. It was found that low protein diets did not depress caloric intake, indicating that observed effects are due to differences in respective nutrient intakes rather than altered caloric intakes. Both the dietary protein and fat levels significantly influenced the fetal cellular growth (cell number rather than cell size) of LAF1/J mice. In addition, dietary fat influenced protein adequacy for satisfactory fetal cellular growth of these mice, probably by altering protein utilization. Optimal fetal cellular growth was obtained with the diet containing 20% casein and 15% fat as indicated by increased fetal protein, DNA, and RNA contents. Normal maternal liver lipid content in animals fed the 20% protein and 15% fat diet also indicates that this diet is optimal for gestational performance of LAF1/J mice.