ESTIMATION OF THE DIRECT AND INDIRECT EXPECTED GENETIC IMPROVEMENT DEPENDING ON THE PHENOTYPIC PERFORMANCE OF AWASSI SHEEP AT WEANING

Abstract

The aim of this study was to investigate the estimation of direct and indirect genetic response dependent on phenotypic values for weaning weight (WWT), number of lambs weaned (LNO) and economic value (EV) of both traits. This study was carried out at the Sheep and Goat Research Station, State Board for Agricultural Research (20 km west of Baghdad), and over the period from 1/7/2008 to 31/1/2009. Data of 603 records of 379 ewe, sired by 48 rams were analyzed. Different criteria of selection program (90, 80, 70, 60 and 50 %) were used to select ewes from the flock. The selection depend on phenotypic values WWT, LNO and EV. The percentage of direct genetic response for WWT were 1.31, 2.19,2.93,3.59 and 4.20% from the flock mean at the selection percentage 90 , 80 , 70 , 60 and 50 % respectively. Direct genetic response of LNO corresponding were 0.57 , 1.14 , 1.79 , 2.53 and 3.27 %, and direct genetic response of EV were 1.20 , 1.97 , 2.60 , 3.19 and 3.72 % respectively. The selection at 50 % of ewes showed a high of direct genetic response 4.20, 3.27, 3.72 for WWT, LNO and EV respectively. The direct selection for LNO showed increase in the percentage of indirect genetic response for WWT and EV (1.70 and 1.52%) at the selection criteria 70%. However the direct selection for WWT and EV showed a decrease in the percentage for LNO at all selection criteria. In conclusion, a positive genetic response dependent on direct selection was found.