Predicted transmitting ability (PTA) of milk yield of 529 sires using animal model (MA), sire model (MT) and herdmate contemporary comparison method (MCR) were calculated and compared by means of correlation's rank and values, reliability, differences among PTA and percent of coincidence in the selection of the best bulls. Two sets of data were considered one contained up to five lactation per cow and other with production data at first lactation. Data of 12,762 lactations of 5757 Gyr and crossbred Gyr Holstein cows were analyzed. Allowing up to five lactation per cow, the rank correlation among PTA calculated using MA and MCR was .69; between MA and MT was .96; and between MT and MCR was .73. The rank correlation between PTA using MA up to five lactation per cow, and PTA calculated by MCR, MT and MA using only the first lactation, were: .60, .76, and .79, respectively. Average reliabilities were greater when animal and sire model were used. These two models were similar in the selection of the best sires according to the PTA values. The estimate reliability when the animal model were used was 11 to 47% greater than the estimated by MCR. These maximum differences were 2% when animal model was compared with sire model.
genetic evaluation; dairy cattle; contemporary herdmates; animal model; mixed model; sire model; Gyr breed
