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Subject: Animal Genetics and Breeding × Author: SUBRAMANYAM, B V × End date: 2013 × Start date: 2012 × Type: Thesis ×
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    ThesisItemOpen Access
    Cytogenetic characterization of Purebred and Crossbred Sahiwal cattle
    (SRI VENKATESWARA VETERINARY UNIVERSITY , TIRUPATI – 517502. (A.P.) INDIA, 2013-03) SUBRAMANYAM, B V; JAYA LAXMI, P (Major); PUNYA KUMARI, B; SIVAKUMAR, A.V.N
    ABSTRACT : A karyological investigation was carried out on Purebred Sahiwal and Jersey X Sahiwal cattle maintained at Department of Livestock Production and Management, College of Veterinary Science, Tirupati to know their chromosomal architecture. Blood samples were collected aseptically into heparinized vaccutainers from thirty two animals of 16 each Sahiwal (8 males and 8 females) and Jersey X Sahiwal (8 males and 8 females). Short-term lymphocyte culture technique was employed for obtaining the metaphase chromosomes. Chromosomes of thirty well spread metaphases from each animal with a total of 960 metaphase spreads from both Purebred Sahiwal and Jersey X Sahiwal Crossbred cattle were screened for chromosomal count and ten metaphases from each animal were taken for karyotyping. The modal diploid chromosome number (2n) in both Sahiwal and Jersey X Sahiwal cattle was found to be 60. All the autosomes were acrocentric and X chromosome was submetacentric in both the Purebred and Crossbred cattle. The Y chromosome was acrocentric in Sahiwal and submetacentric in Jersey X Sahiwal. The effect of genetic group and sex of the animal on all the morphometric measurements were studied. The analysis of variance based on the arcsin transformed data revealed significant (P ≤ 0.01) differences among the relative lengths of individual chromosomes in both Sahiwal and Jersey X Sahiwal cattle indicating that the relative contribution of the chromosomes to the total genome is different. The effect of genetic group and sex of the animal on relative lengths, arm ratio, centromeric index and morphological index of individual chromosomes in both Sahiwal and Jersey X Sahiwal cattle was found to be non significant. The relative length of the autosomes ranged from 1.74 ± 0.01 to 5.28 ± 0.02 per cent in Sahiwal cattle and from 1.72 ± 0.01 to 5.26 ± 0.02 per cent in Jersey X Sahiwal cattle. The first chromosome was found to be the longest chromosome of the karyotype in both the genetic groups. The X chromosome was the second largest chromosome and contributed to 5.07 ± 0.03 percent of the total genome in Sahiwal cattle and 5.06 ± 0.05 percent in Jersey X Sahiwal. The relative length of Y-chromosome was 1.99 ± 0.02 per cent in Sahiwal and 2.20 ± 0.02 percent in Jersey X Sahiwal cattle. The arm ratio, centromeric index and morphological index for the X-chromosome of Sahiwal cattle were 1.89 ± 0.02, 0.35 ± 0.01 and 2.87 ± 0.04, respectively. The arm ratio, centromeric index and morphological index for the X-chromosome of Jersey X Sahiwal cattle were 1.84 ± 0.03, 0.36 ± 0.01 and 2.76 ± 0.04, respectively. The arm ratio, centromeric index and morphological index for the Y-chromosome of Jersey X Sahiwal cattle were 1.63 ± 0.04, 0.35 ± 0.01 and 1.41 ± 0.04, respectively. The chromosome architecture of Sahiwal cattle was found to be similar to that of different recognized breeds of Zebu cattle whereas for Jersey X Sahiwal cattle resembled that of Bos taurus cattle.