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Subject: Animal Genetics and Breeding × Author: SATISH KUMAR, ILLA × End date: 2013 × Start date: 2012 × Type: Thesis ×
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    ThesisItemOpen Access
    CYTOGENETIC CHARACTERIZATION OF VIZIANAGARAM SHEEP
    (Sri Venkateswara Veterinary University, TIRUPATI – 517 502,A.P, 2012-01) SATISH KUMAR, ILLA; PUNYA KUMARI, B (Major); GNANA PRAKASH, M; SURESH, J
    ABSTRACT : A study was carried out on 60 Vizianagaram sheep (30 males and 30 females) for cytogenetic characterization. The modal diploid chromosome number was found to be 54. The first three pairs of the autosomes were submetacentric and the remaining 23 pairs of autosomes were acrocentric in nature. The X – chromosome was the longest acrocentric, while the Y – chromosome was the smallest biarmed chromosome. The effect of sex was not evident on the morphometric measurements of all the chromosomes, while, the differences among the chromosomes were significant among all the chromosomes for all the morphometric measurements. The mean relative length of autosomes varied from 1.54 ± 0.04 to 9.59 ± 0.12 percent. The X – chromosome constituted 5.06 ± 0.02 percent to the total genome, while the Y – chromosome constituted 1.81 ± 0.17 to the total genome. Sex had no significant effect on the relative length of any one of the chromosomes in the karyotype. The mean arm ratios for the first three biarmed autosomes based on raw data varied from 1.24 ± 0.07 to 1.31 ± 0.07, while the mean arm ratios based on transformed data ranged from 6.34 ± 0.01 to 6.58 ± 0.01. The sex had no influence on arm ratios of any one of the chromosomes under study. The overall mean centromeric indices based on raw data for the first three chromosomes are 0.565 ± 0.07, 0.550 ± 0.04 and 0.545 ± 0.04, respectively. Significant differences were observed in centromeric indices of first three biarmed autosomes, while the influence of sex on centromeric indices of all the chromosomes was found to be non -significant. The overall mean morphological indices based on transformed data ranged from 13.31 ± 0.05 in third chromosome to 15.88 ± 0.08 in first chromosome. The effect of sex was not evident on the morphological indices of the first three chromosomes, while, the differences among the chromosomes are significant.