Demografia e estrutura populacional da raça caprina Moxóto com base em análise de pedigree

Abstract

Among the several locally adapted genetic groups of goats from Northeast of Brazil, the Moxotó breed stands out. Despite its importance, the breed has been suffering a genetic dilution and, consequently, its currently considered as endangered. An important factor to understand the existing genetic variability is the study of demography and populational structure, which allows the determination of the level of risk of the breed. The definition of the degree of endangerment of a breed is essential for the definition of efficient genetic enhancement and conservation programs. The present study aimed to evaluate the demography and populational structure of Moxotó breed using the pedigree analysis. Were used information from 571 animals, from 5 herds. The data collection was done between 1981 and 2007. Were estimated the endogamy (ΔF), average kinship coefficient (AR), effective number of founder animals ( ), effective number of ancestors ( ), Wright’s F-statistics (Fis, Fit e Fst), the genetic contribution of the herds and the generation intervals (IEG). The statistical analysis was done with the support of Endog® v4.8 software. It was observed a value of 31 for , close to the value of (36). From the total pedigree information, only 15,76% had information about the father and, 15,41% had information about the mother. Due to the amount of incomplete information on the pedigree it was not possible to calculate the average inbreeding coefficient (F) for the population nor for generations. A significantly low value of ancestors (N=12) explain 50% of the genetic variability of the population. The Fit value (-0,001483) indicates the presence of genetic variability in the population. The Fst value (0,004396) indicates the existence of genetic diversity among subpopulations. The -0,005905 of FIS indicates the existence of genetic variability inside the population. Despite the reduced effective number, there is still genetic diversity inter and intra-population that can be used by genetic conservation and genetic enhancement programs. Under this conditions, programs of genetic enhancement should be avoided until the effective numbers are fully recovered.