Maternal Influence on Body Weight

A cross-nursing experiment in mice was employed to study the relative contributions of prenatal and postnatal factors to body weight at 5, 12 and 21 days and 6 weeks. Postnatal maternal influence was found to be the most important single factor in determining weight through weaning. The weight at 12 days was largely controlled by postnatal factors which suggested its use as a measure of lactation performance in the dam. Postnatal maternal influences accounted for 71.5% of the variance in the 12-day weight of litters of six mice. The prenatal influences accounted for an additional 9.7% of the variance in 12-day litter weight.