Abstract
Days open (DO), number of service per conception (NOS), birth weight of dams and their heifers (EW1, BW2) were used as variables in heifers selection subindices. A 3225 complete lactation record of 812 cows were involved in construction of dam-heifer selection subindices (I-1: all the four traits were included, I-2: only BW1, BW2 and DO, and I-3. only BW1, BW2 and NOS). Cows were daughters of 185 sires. Number of cow; per sire ranged from 4 to 5. Variance and covariance estimates as well as fixed random effects were estimated by mixed model of Maximum Likelihood Procedures. The selection subindices and traits were estimated according to their effect on genetic gain Relative efficiency of I2 and I3 to I1 were 84.18% and 84.27% in selection for DO, respectively and 163.84% and 77.84% in selection for NOS in the same order. The best subindices for DO and NOS improvement were I1 and I2. The expected genetic gain in NOS and DO per generation were low and ranged between 0.8993 to 0.9563 services and 7.81 to 9.28 days respectively.