Description

A cytogenetic study was conducted on 38 Ongole cattle maintained at Livestock Research Station, Lam, Guntur and nearby villages by utilizing short-term lymphocyte culture technique. The normal diploid chromosome number was 60 which consisted of 29 pairs of acrocentric autosomes and one pair of sex chromosomes. The X-chromosome was sub-metacentric and Y chromosome was acrocentric. The morphometric measurements of chromosomes obtained from farm bred animals and those from field animals did not differ significantly. The relative lengths (RL) of chromosomes 1, 5, 6, 15, 16, 17, 18, 23, 24, 25, 26, 27, 28, 29 and X chromosome were significantly different among the sexes. The RL of autosomes ranged from 1.92 ± 0.01 to 5.24 ± 0.02 per cent. The X-chromosome was the longest while Y-chromosome was the shortest and contributed 5.42 ± 0.03 and 1.79 ± 0.02 per cent to the genome. The decline in the RL of the chromosomes was sharp from 1 to 3 and was gradual thereafter. The arm ratio, centromeric index and morphological index for the X-chromosome were 1.87 ± 0.015, 0.35 ± 0.002 and 5.25 ± 0.075, respectively.