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The present study was conducted to characterize lifetime performance of Barki ewes, estimating some genetic and phenotypic parameters for total lifetime performance traits and investigate the possibility of improving these traits. Lifetime performance records for 1040 Barki ewes daughters of 194 sires and 729 dams were obtained from 1963 to 2010 from the sheep flock of the Desert Research Centre and used in the present study. Data was analyzed using SAS and MTDFREML programs to carry out analysis of variance and estimate genetic and phenotypic parameters for the studied traits. The current study dealt with lifespan, productive, reproductive and partial lifetime productive traits. Lifespan traits included total lifetime, TLT, productive life, PL and lifetime score. Lifetime productive traits included total number and weight of lambs born and weaned. Lifetime reproductive traits included age at first lambing, AgFL, and lambing interval, LI. Three partial life time productive traits were calculated i.e., after the first lambing, cumulative first two lambing, and cumulative three lambing. Results showed that throughout the lifetime, Barki ewe on the average gave birth to 2.77 lambs weighing 9.74 kg at birth and able to rear 2.53 weaned lambs weighing 49.01 kg at weaning. Barki ewes showed an average TLT of 2301.63 days (i.e., 6.3 years), during which she has 2.71 lambing season. PL represented 37.8% of TLT of the ewe while AgFL, accounted for 39% of TLT. Average LI, was 344.44 days. The present study emphasized on improving reproductive efficiency of Barki ewes in this flock rather than removing nonlambing ewes. Birth year had highly significant effect on all studied traits. Heritabilities were estimated for lifetime productive traits (ranged from 0.24 to 0.31), lifespan traits (ranged from 0.07 to 0.16) and lifetime reproductive traits (ranged from 0.03 to 0.12). Highly significant and positive genetic and phenotypic correlations were obtained between lifetime productive traits and lifespan traits. The partial trait of weight of lambs weaned for the first three lambing was found to be moderately heritable and highly significant positively associated genetically and phenotypically with the total weight of lamb weaned (TWLW) which recommend the utility of this trait as an indirect selection criterion to improve the TWLW throughout the lifetime. Selection based on total weight of lambs weaned after the first lambing is likely to achieve the target at an earlier stage.

RELATIONSHIPS AMONG SOME GROWTH PERFORMANCE TRAITS AND LIFETIME PRODUCTIVITY OF BARKI EWES