ESTUDO DA VARIABILIDADE GENÉTICA DE RESISTÊNCIA A NEMATÓDEOS GASTRINTESTINAIS EM OVINOS DA RAÇA CORRIEDALE COM MARCADORES RAPD RAPD MARKERS TO STUDY GENETIC VARIABILITY TO GASTROINTESTINAL NEMATODES IN CORRIEDALE BREED SHEEP

The genetic variability for resistance of 117 Corriedale Iambs naturally infected with gastrointestinal nematodes, as a starting point for the selection of breeds, was analysed by clustering procedures through Average Linkage and Principal Component analyses, using data from 68, 135, 211 and 264 RAPD markers. Analyses of Variance and Correlations were also performed. The animals were spread into a normal distribution within three phenotypic classes of LogEPG, where the LogEPG highest values were 100-fold superior to the lower values. There are sex, parent and challenge effects on the Iamb LogEPGs. From the higher number of markers it is possible to identify up to five genetic groups where the majority of Iambs present equal response to the endoparasites. The results allowed to conclude that there is genetic variability for resistance to gastrointestinal nematode parasites in Corriedale lambs, as detected by the RAPD technique, discriminating individuals with distinct responses when more than 250 markers were applied.