Cytogenetic studies on Japanese quail.

Fifteen male and fifteen female black Japanese quails and 45 embryonated eggs obtained from the Poultry Experimental Station, College of Veterinary Science, Hyderabad, were utilized for the present study. The chromosome number varied from 76 to 81 with a modal chromosome number of 78. Five pairs of autosomes were macrochromosomes, which were sub-metacentric while the remaining were microchromosomes, whose morphology could not be ascertained. The Z-chromosome was identified as the fifth largest unpaired bi-armed chromosome in females and paired in males, while the W-chromosome was identified as the microchromosome in the size class of 7 to 8 chromosomes. Sex of the bird and the technique of obtaining metaphases had significant effect on the morphometric measurements of some chromosomes. The overall means of relative length, arm ratio, centromeric index and morphological index for the autosomes ranged from 0.95±0.0004 to 10.58±0.0015 percent, 1.20±0.02 to 2.38±0.07, 0.54±0.005 to 0.70±0.007 and 5.98±0.14 to 7.90±0.24, respectively. The mean relative lengths of Z- and W-chromosomes were 4.66±0.0006 and 2.47±0.0005 percent, respectively. The arm ratio, centromeric index and morphological index of the Z-chromosome were found to be 1.04±0.01, 0.51±0.002 and 7.14±0.19, respectively. Among the autosomes, the five macrochromosomes contributed 36.08 per cent to the genome.