CYTOGENETIC STUDIES IN DOMESTIC PIG (SUS SCROFA)
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Date
2011-08
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Sri Venkateswara Veterinary University, TIRUPATI – 517 502,A.P
Abstract
ABSTRACT :
A karyological study was undertaken on Crossbred pigs (15 males 15 females) maintained at All India Coordinated Research Project on Pigs (AICRP), College of Veterinary Science, Tirupati and on indigenous pigs (15 males and 15 females) present in and around Tirupati to study their chromosomal profile by employing the short term peripheral blood lymphocyte culture technique.
The modal chromosome number (2n) in both crossbred and indigenous pigs was found to be 38 and a fundamental number of 64 as in the exotic. Among autosomes, first 5 pairs were submetacentric (first chromosome was the longest pair), next two pairs were sub telocentric (6-7), subsequent 5 pairs were metacentric (8-12) and remaining six pairs were telocentric (13-18) and the thirteenth pair was the second largest in the karyotype of the pig. The X chromosome was metacentric and Y chromosome was smallest metacentric among all the members of the karyotype. The effects of genetic group and sex on all the morphometric measurements were studied. The analysis of variance based on the arcsin transformed data revealed that genetic group had a significant effect on the relative length of chromosomes 2, 3, 4, 5, 6, 8, 9, 10, 12, 13, 15, 16, 17 and allosomes, while sex had no significant effect on the relative length of any one of the chromosomes in both genetic groups. The overall means of relative lengths based on raw data for the autosomes and allosomes ranged from 2.03 ± 0.04 to 10.99 ± 0.21 and 1.99 ± 0.01 to 11.23 ± 0.09 percent in crossbred and indigenous pigs, respectively.
Genetic group had significant effect on arm ratio of first 12 pairs of autosomes (except seventh chromosome), X and Y-chromosome while, the sex had no influence on arm ratios of all the chromosomes. The arm ratio among autosomes and allosomes ranged from 1.02 ± 0.06 to 2.90 ± 0.09 and 1.04 ± 0.05 to 2.95 ± 0.02 in crossbred and indigenous pigs, respectively.
Significant differences were observed in centromeric indices of autosomes (2 and 9) and allosomes between two genetic groups, while the influence of sex on centromeric indices of all the chromosomes was found to be non significant. The mean centromeric indices ranged from 0.52 ± 0.08 to 0.74 ± 0.01 in crossbred and 0.51 ± 0.14 to 0.75 ± 0.09 in indigenous pigs.
Morphological indices of all the autosomes were significantly influenced by the genetic group, whereas, sex had no significant effect on morphological indices of all the chromosomes. The overall mean morphological indices ranged from 2.07 ± 0.06 to 7.57 ± 0.16 in crossbred and 2.08 ± 0.07 to 8.08 ± 0.15 in indigenous pigs.
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Keywords
PIG; CYTOGENETIC STUDIES