FLOCK DYNAMICS OF DESERT BARKI SHEEP IN RELATION TO AGE STRUCTURE

Abstract

Data utilized in the present st•Jdy were obtained from Ras­ Elhekma and Maryout research stations of the Desert Research Center. The reproductive data of 8689 ewe records spread over 40 years (from 1960 to 2000) representing 2952 breeding ewes were utilized for this study. The .study was designed to assess the flock . dynamic of Barki sheep with different age - structures. The overall means of the studied traits Epj, LBJ, Lw1• L8p, LwP, LEii• dam mortality, dam disposal, and ewe lambs mortality were 79%, 81.6%, 65.9%, 1.033, 1.024, 0.275, 9.3, 14.9%, and 10.5'%, respectively. Age of ewe exerted a significant influence on all sJ;Udied traits except LEii and ewe lambs' mortality. Mating season had significantly effect on all studied traits except dam mortality and ewe lambs mortality. Location exerted a significant effect on dam disposal rate, Lw1 and L8p. The annual replacement rates were 19.2%, 16.3%, 16.4% and 19.1% for summer mating season, autumn mating season, Ras-Elhekma and Maryout research stations, re.spectively. The values of R, for the optimum age structure were 1.013, 1.107, 1.101 and 1.014 with 5, 4, 4, 5 age groups for summer mating season, autumn mating season, Ras-Elhekma and Maryout research stations, respectively. The intrinsic rate of increase (rm) were zero or more when the flock consisted of 5, 4, 4, and 5 age groups for summer mating season, autumn mating season, Ras-Elhekma and Maryout research stations, respectively.