Abstract :
Three Egyptian sheep breeds (Rahmani, n = 40; Barki, n = 50; Ossimi, n = 36) were used to
investigate the effect of backfat thickness of ewes, at mating, on their subsequent reproductive
and productive performances. Ewes were assigned to four groups, according to their
backfat thickness (<1; 1 to <1.5; 1.5 to <2;
≥2 mm) respectively. The experimental design
was thus completely randomized with the 12 groups arranged factorially (3
×
4), according
to breed and backfat thickness. Ewe breeds did not significantly affect the studied reproductive
and productive traits. However, the backfat thickness of the ewes significantly affected
all the reproductive and productive traits, except for ewes conceived/ewes joined, and
lambs born/ewe lambing. Superior performances were recorded for ewes with a backfat
thickness of 1.5 to <2 mm and those having
≥2 mm – where the lambs weaned/ewe joined
increased from 43% in the lowest backfat thickness group (<1 mm) to 73% and 77% in the
higher backfat thickness groups (1.5 to <2 mm and
≥2 mm groups, respectively). The kg
lamb weaned/ewe joined increased gradually by increasing the backfat thickness of the
ewes from 6.2 kg in the lowest backfat thickness group, to 14 kg in the highest backfat
thickness group. However, no significant differences were recorded for ewes with a backfat
thickness of 1.5 to <2 mm, and those having
≥2 mm regarding all the reproductive and
productive traits, except for ovulation rate. Therefore, to optimize the profitability in sheep
flocks, it is recommended to control the backfat thickness of ewes at mating between 1.5
and 2 mm.
