Browsing by Author "Kathiravan, P"
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ArticleItem Open Access Genetic architecture and bottleneck analyses of Salem Black goat breed based on microsatellite markers(2014-09) Thiruvenkadan, AK; Jayakumar, V; Kathiravan, P; Saravanan, R; TANUVASAim: The present study was undertaken in Salem Black goat population for genetic analysis at molecular level to exploit the breed for planning sustainable improvement, conservation and utilization, which subsequently can improve the livelihood of its stakeholders. Materials and Methods: Genomic DNA was isolated from blood samples of 50 unrelated Salem Black goats with typical phenotypic features in several villages in the breeding tract and the genetic characterization and bottleneck analysis in Salem Black goat was done using 25 microsatellite markers as recommended by the Food and Agricultural Organization, Rome, Italy. The basic measures of genetic variation were computed using bioinformatic software. To evaluate the Salem Black goats for mutation drift equilibrium, three tests were performed under three different mutation models, viz., infinite allele model (IAM), stepwise mutation model (SMM) and two-phase model (TPM) and the observed gene diversity (He) and expected equilibrium gene diversity (Heq) were estimated under different models of microsatellite evolution. Results: The study revealed that the observed number of alleles ranged from 4 (ETH10, ILSTS008) to 17 (BM64444) with a total of 213 alleles and mean of 10.14±0.83 alleles across loci. The overall observed heterozygosity, expected heterozygosity, inbreeding estimate and polymorphism information content values were 0.631±0.041, 0.820±0.024, 0.233±0.044 and 0.786±0.023 respectively indicating high genetic diversity. The average observed gene diversities (He) pooled over different markers was 0.829±0.024 and the average expected gene diversities under IAM, TPM and SMM models were 0.769±0.026, 0.808±0.024 and 0.837±0.020 respectively. The number of loci found to exhibit gene diversity excess under IAM, TPM and SMM models were 18, 17 and 12 respectively. Conclusion: All the three statistical tests, viz., sign test, standardized differences test and Wilcoxon sign rank test, revealed significant deviation of Salem Black goats from mutation-drift equilibrium under IAM and TPM models, however, nonsignificant deviation under SMM model. The qualitative test of mode shift analysis supported the results under SMM indicating the absence of the genetic bottleneck in the recent past in Salem Black goats.ArticleItem Open Access GENETIC DIVERSITY AND BOTTLENECK ANALYSIS OF SHEEP BASED ON MICROSATELLITE MARKERS(Indian Society for Sheep and Goat Production and Utilization, 2019) Selvam, R; Kathiravan, P; TANUVASThe genetic diversity of Madras Red sheep at Post Graduate Research Institute in Animal Sciences, Kattupakkam (Tamil Nadu) and Mecheri sheep at Mecheri Sheep Research Station, Pottaneri (Tamil Nadu) was analysed using FAO recommended microsatellite markers. Genetic variation at 10 microsatellite loci, population structure and genetic bottleneck analysis were done to provide genetic information. A total of 98 and 86 alleles were scored for Madras Red and Mecheri sheep, respectively. The polymorphism information content ranged from 0.609 to 0.902 for all the microsatellite loci. The overall observed and estimated heterozygosity for all loci combined were 0.972 and 0.785 for Madras Red and 0.982 and 0.774 for Mecheri sheep, respectively. The average and total heterozygosity of subpopulation was 0.779 and 0.821, respectively. The coefficient of gene differentiation was 0.049 between the breeds which indicates that the genetic diversity is low between the Madras Red and Mecheri breeds of sheep with respect to microsatellite loci studied. The study revealed no genetic bottleneck in recent past and this was confirmed by mode shift test which gave L-shaped distribution for proportion of alleles, indicating that the population is stable with respect to population size. The panel of microsatellites used was highly informative for molecular characterization and could be used for exploitation of genetic diversity of the related breeds for conservation.ArticleItem Open Access Microsatellite based genetic characterization of Kanni Adu, Kodi Adu and Salem Black goats of Tamil Nadu(ICAR, 2014-09) Jeyakumar, M; Thiruvenkadan, AK; Saravanan, R; Kathiravan, P; Panneerselvam, S; Malmarugan, S; TANUVASGoat is a multi-functional animal and plays a significant role in the economy and nutrition of landless, small and marginal farmers in India. India has 23 recognized goat breeds adapted to different agro-climatic conditions. These different goat breeds represent important genetic resources because of their special economic and ecological characteristics. Tamil Nadu is situated in southern part of India and bestowed with Kanni Adu, Kodi Adu and Salem Black goat breeds (Acharya 1982, Thiruvenkadan et al. 2000, Thiruvenkadan and Karunanithi 2006, Thiruvenkadan 2012). These breeds are well adapted to their environment and are important economic resource. Genetic variation within and between breeds is warranted to differentiate them on a genetic basis. The resulting genetic information may assist in choosing the best conservation and improvement options for these genetic resources. Advances in biotechnology offer possibilities of improving, utilizing and conserving present domestic animal diversity. Molecular markers have been shown to be an efficient tool in quantification of genetic diversity of various populations. Microsatellite markers are best suited to characterize the genetic variability within and between populations because of their high variability, distribution throughout the genome, co-dominant inheritance and neutrality to selection (Boyce et al. 1996).ArticleItem Open Access Microsatellite- based phylogeny of Indian sheep breeds(Agricultural Research Communication Center, 2015) Ramachandran, A; Thiruvenkadan, AK; Kathiravan, P; Panneerselvam, S; Elango, A; TANUVASGenetic diversity of south Indian meat type breeds was investigated by means of 15 ovine microsatellite markers. All used microsatellites amplified well and exhibited polymorphisms. A wide range of genetic variability was observed as allele varied from 4 to 10 in Madras Red; 4 to 10 in Mecheri; 4 to 12 in Pattanam; and 3 to 12 in Nellore sheep breeds. The mean number of alleles observed in Madras Red, Mecheri, Pattanam and Nellore breeds were 6.5, 6.7, 7.0 and 7.2 respectively. Average observed and expected heterozygosities over the different breeds were 0.23 to 0.87 and 0.347 to 0.827 respectively. The most diverse sheep breed was Nellore breed and the least diverse breed was Madras Red, which had the lowest total number of alleles (na=98) and lowest average observed (Ho=0.576) and expected (Ho=0.594) heterozygosities. The multi-locus mean between-population variability (FST) values indicated that about 5.60% of the total genetic variation was explained by population differences, whereas, the remaining 94.40% is due to differences among individuals within breeds. The values of FIT in the sub population for the most of markers were positive which showed the deficiency of heterozygotes. The DA genetic distance and FST distances between pairs of breeds revealed that the lowest distance was between Madras Red and Mecheri and the highest between Mecheri and Nellore breeds. Analysis of individual genotypes provided valuable information for understanding intra and inter-population genetic differences and helps in planning genetic improvement and conservation strategies for further improvement and sustainable utilization.ArticleItem Open Access SEX RATIO AND REPRODUCTIVE PERFORMANCE OF MADRAS RED SHEEP UNDER FIELD CONDITIONS(2011) Balasubramanyam, D; Jaishankar, S; Kathiravan, P; Sivaselvam, SN; TANUVASThe sex ratio and reproductive performance of Madras Red sheep under field condition was recorded during the period 1997 - 2009. The lambing percentage ranged from 80.32 to 90.56 with an overall of 86.01 ± 0.91%. The total number of lambing recorded during the period of study was 27,967. Out of these 99.936% were born single, 0.060% births were twins and only one was triplet (0.004%). The male : female sex ratio of overall births recorded was 47.82 : 52.18 The male : female sex ratio of single births, twin births and triplet births recorded in the present study were 48.07 : 51.93, 44.12 : 55.88 and 66.67 : 33.33 respectively.