Poultry biodiversity is considered one of the most endangered genetic resource. The determination of within-populations genetic characterization is a basic step in the evaluation of local breeds as genetic resources. Microsatellites markers are a convenient and powerful tool in heterozygosity and genetic distances determination at DNA level. Information about traditional Italian chicken breeds characteristics is scarce and the investigation of their genetic make-up plays an important role in conservation programmes supplying objective selection supports. Valdarnese Bianca (VB) is a traditional white feathered breed from Tuscany, cock weight 3.13.5Kg, hen weight 2.5-3.0Kg. Eggshell: white, average egg weight: 50g, average number of egg per year: 135, hen age at first egg: 7 months, slaughter age for broiler: 120d or more. 83 VB birds from 10 different breeding-farms were analysed (4-13 birds/farm), 3 Livornese Bianca (LB) and 3 Golden Comet (GC) (commercial hybrid) samples were added in the analysis as control groups. Genomic DNA was extracted from blood samples using classic procedures. All birds were genotyped at 8 microsatellite loci (ADL102, ADL158, ADL176, ADL181, ADL210, ADL267, ADL136, ADL 171). PCR amplification: 10μl volumes with 25 ng of template DNA. PCR products were separated by electrophoresis in 4.2% denaturing polyacrylamide gels on ABI Prism 377 DNA Sequencer equipped with Genescan and Genotyper softwares (Applied Biosystems). Allele frequencies and deviation from Hardy-Weinberg equilibrium (P-value) at the eight microsatellite loci were calculated using the GENEPOP statistic package; in case of less than five alleles, an extract P-value, by the complete enumeration method was calculated, while for more than five alleles a Markov-Chain method was computed. The heterozygosities (HO, HE) were calculated by FSTAT. Factorial analysis three-dimensional distribution was carried out using the GENETIX program (12 populations). A total of 73 alleles was detected across the 8 loci. The lowest allele number was calculated in ADL 181 and ADL 210 (6 alleles). The highest allele number was calculated in ADL 136 (15 alleles). HO ranged from 0.355 (ADL 210) to 0.654 (ADL 181).The test for H-W equilibrium revealed significant deviations (P<0.05); 5 farmpopulations of VB were in equilibrium. Genetic differences within VB breeding stocks were detected. ___________________________________________________________________________
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