Vinoo, R(MAJOR)Muralidhar, MJagadeeswara Rao, SVENKATA PRANEETH, D2018-06-232018-06-232017-01http://krishikosh.egranth.ac.in/handle/1/5810055359ABSTRACT : The primary objective in small animal production is to have higher meat production. The present study is aimed at understanding natural variation of GDF8 locus in Nellore and Macherla Brown sheep genetic groups by using PCR-RFLP. DNA was isolated from 100 sheep blood samples using a modified high salt method. Two sets of primers were designed to amplify regions of exon 3 and intron 1 of GDF8 gene. A total of 100 blood samples from the three sheep populations were used for amplification of exon 3 and 65 samples were used for amplification of intron 1. The PCR products were subjected to RFLP with HaeIII restriction enzyme for exon 3 and HpyCH4V restriction enzyme for intron 1. Based on different genotypes obtained the genotypic and allelic frequencies were determined. In the present study exon 3 is monomorphic in all the samples and hence, further analysis could not be performed on this locus. The intron 1 region was polymorphic representing HH, Hh, hh genotypes. The heterozygosity values for intron 1 region were 0.48, 0.49 and 0.47 for Nellore Jodipi, Nellore Brown and Macherla Brown genetic groups respectively. The PIC values for Nellore Jodipi, Nellore Brown and Macherla Brown are 0.37, 0.37 and 0.36 respectively, suggesting considerable amount of variation exist in these populations. The allelic frequencies of Nellore Jodipi, Nellore Brown and Macherla Brown were 0.59 and 0.41, 0.56 and 0.44, 0.62 and 0.38 for H and h alleles, respectively. Diversity estimates (FIS) were negative for the three populations indicating that there is no differentiation among the three populations. The test for Hardy Weinberg Equilibrium indicated that the three populations are departing from the equilibrium assumptions. No significant (P>0.05) association of a genotype with body weights at different ages was observed in the present study in both the genetic groups of Nellore Jodipi and Nellore Brown. A new PCR-RFLP marker is designed for intron 1 in this study which is found to be polymorphic and useful in population studies.ennullThesis