Cytogenetic characterization of Coimbatore sheep

The present study was conducted to assess the chromosome profile and morphometric characteristics of Coimbatore sheep. The diploid chromosome number was found to be 54 (2n). The first three pairs of autosomes were bi-armed, metacentric and the remaining 23 pairs of autosomes were acrocentric. The X-chromosome was the largest acrocentric and the Y-chromosome was the smallest metacentric. The mean relative length varied between 1.83 and 9.18. The biarmed autosomes contributed 24.9% of the total genome while X- and Y-chromosomes contributed 5.12 and 1.80%, respectively. The morphometric characteristics viz. arm ratio, centromeric indices (CI₁ and CI₂) and morphological index confirmed the metacentric nature of biarmed chromosomes. The GTG-banding patterns of chromosomes were similar and on par with the standard karyotype (ISCNDB, 2000) and facilitated easy pairing and identification of chromosomes.