CYTOGENETIC CHARACTERIZATION OF MACHERLA BROWN SHEEP

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Date
2014-08
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SRI VENKATESWARA VETERINARY UNIVERSITY TIRUPATI - 517 502. (A.P.) INDIA
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ABSTRACT : A karyological study was conducted on Macherla Brown sheep maintained in four districts namely Prakasam, Guntur, Krishna and Nalgonda districts of Andhra Pradesh. Blood samples were collected from 80 animals (40 males and 40 females) of field flocks to analyse the chromosomal profiles by employing the short term lymphocyte culture technique. The modal diploid chromosome number was found to be 54 (2n = 54, XY). The first three pairs of the autosomes were found to be submetacentric and the remaining 23 pairs of autosomes were acrocentric. The X-chromosome was the longest acrocentric, while the Y-chromosome was the smallest biarmed chromosome in the karyotype. The effect of sex on all the morphometric measurements was studied. The analysis of variance based on the arcsin transformed data revealed that sex had no significant effect on the relative length of chromosomes. The mean relative lengths based on raw data for the autosomes varied from 1.80 ± 0.01 to 9.76 ± 0.03. The X-chromosome constituted 5.05 ± 0.01 percent to the total genome, whereas the Y chromosome constituted 1.57 ± 0.01 percent to the total genome. The overall mean arm ratios for the first three biarmed autosomes based on raw data varied from 1.20 ± 0.02 to 1.23 ± 0.01, while the mean arm ratios based on transformed data varied from 6.30 ± 0.01 to 6.37 ± 0.01 and found that sex had no significant effect on arm ratios of first three biarmed autosomes. The overall mean centromeric indices (C.I.1) for the first three biarmed autosomes based on raw data are 0.452 ± 0.01, 0.452 ± 0.01 and 0.460 ± 0.01, respectively. Significant differences were observed among the chromosomes but sex had no significant effect on centromeric indices. (C.I.1). The overall mean centromeric indices (C.I.2) for the first three biarmed autosomes based on raw data are 0.548 ± 0.01, 0.550 ± 0.01 and 0.544 ± 0.01 respectively. The effect of sex was not evident on centromeric indices for the first three biarmed autosomes. The overall mean morphological indices for the first three biarmed autosomes based on transformed data varied from 14.82 ± 0.05 in third biarmed autosome to 16.65 ± 0.06 in first biarmed autosome and sex had no significant effect on morphological indices, while significant differences exists between chromosomes.
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