Studies on Reproduction In Sheep

Fertility is considered one of the most important performance in sheep and is affected by genetic disturbances.The present work was undertaken on local breed ewes and rams to determine the possibly found chromosomal aberrations in different clinical causes of infertility or sterility.The materials of this work included 48 Ossimi and Rahmani ewes and 24 rams of the same breeds raised in Sharkia Province, Egypt. These animals were grouped according to their reproductive disturbances into 8 groups In addition to the control groups for bo1- Subgroup 1: Sexually normal fertile ewes: This subgroup consisted of 10 sexually normal fertile ewes (30-54months old) and all of them were pregnant at the time of investigation.500 metaphase spreads were examined. The chromosomal complement(2n) was 54,:XX (52 autosomes and 2 sex chromosomes). Three pairs ofthe autosomes were metacentrics while the other 24 pairs were allacrocentric autosomes, including the two sex chromosomes (XX). Thesex chromosomes were the largest acrocentric chromosomes present.Among the total 500 examined metaphases only 14 aberrated cells (2.8%)were obtained. The classification of these abnormalities was as follows;centromeric attenuations (1.0%), deletions (0.4%), gaps (0.8%)