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Subject: Animal Genetics and Breeding × Author: SUREKHA, J × End date: 2015 × Start date: 2015 ×
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    ThesisItemOpen Access
    MOLECULAR GENETIC CHARACTERIZATION OF NELLORE SHEEP
    (SRI VENKATESWARA VETERINARY UNIVERSITY TIRUPATI - 517 502. (A.P.) INDIA, 2015-01) SUREKHA, J; Punya Kumari, B(MAJOR); Gnana Prakash, M; Suresh, J
    ABSTRACT : Nellore sheep is the tallest sheep breed of India whose home tract is Nellore and Prakasam Districts of Andhra Pradesh, but distributed throughout Andhra Pradesh and in certain areas of Telangana state. Nellore is a meat type breed known for heat tolerance, disease resistance and thrives well in harsh climatic conditions. The assessment of genetic variation is important to monitor the gene flow in populations, for conservation of breed and also to determine the level of inbreeding in the population. The present study was carried out to characterize Nellore sheep at molecular level to understand the genetic constitution of population, properly asses the value of breeds and to guide decision making in livestock development and breeding programmes. The characterization was done by fifteen microsatellite markers recommended by FAO for population diversity studies in sheep. DNA was isolated from blood samples by phenol-chloroform method and microsatellites were amplified by Polymerase Chain Reaction. The PCR products were resolved using agarose gel electrophorosis. The genotypes were scored and the number, size, frequency of alleles was calculated using POPGENE software. In the sampled population for the fifteen marker loci under investigation a total of 129 alleles were observed. The number of alleles at each locus varied from a minimum of four to a maximum of twelve with a mean of 8.6 alleles across all loci. Allele size ranged from a minimum of 78 bp (OarCP49) to a maximum of 294 bp (HSC), while allele frequency varied between 0.0104 (MAF214) to 0.5102 (OarHH64). The most frequent allele number was eight. The number of effective alleles across fifteen microsatellite loci studied ranged from 2.6027 (OarHH64) to 9.0530 (MAF214). The mean number of effective alleles was 6.766 ± 0.461 across all loci. The expected heterozygosity ranged from 0.6221 (OarHH64) to 0.9022 (OarJMP8) with a mean value of 0.837 ± 0.018, whereas, the observed heterozygosity ranged from 0 (BM827, OarHH41, BM6506 and HUJ616) to 0.3061 (OarCP34) with a mean value of 0.098 ± 0.025. All the fifteen microsatellite loci (100 percent) were found to be highly polymorphic and the PIC values ranged from 0.5465 (OarHH64) to 0.8951 (MAF214). The mean PIC value for all the fifteen loci was found to be 0.819 ± 0.21. The Chi-square test revealed that all the fifteen loci were showing significant deviation from Hardy-Weinberg Equilibrium. The inbreeding estimate values obtained in this study were all positive and ranged from 0.6300 (OarCP34) to 1.000 (BM827, BM6506, HUJ616 and OarHH41). The mean FIS value was 0.919 ± 0.025 indicating the deficiency of heterozygotes.