Date of this Version
The genetic model for fetal effect on production of the dam is described, and studies on genetic and economic implications are reviewed. The effect on production from the sire of the cow has 1.58 to 3.02 times as much economic value as the effect from the sire of the fetus. The use of mate records in evaluating a sire in addition to daughter records could increase economic gain from selection by 1 to 2% depending on the variation from sire of fetus. Mate records alone do not appear valuable for sire selection. About 1% of the variation in milk yield appears to be due to the effect of sire of fetus as indicated by a summary of various estimates and from consideration of the data and methods used to obtain the estimates. The correlation between effects of sire of fetus and sire of cow appears to be nearly zero. A method of joint evaluation of bulls as sires of cows or as sires of fetuses is described.