Erica Perez Marson, José Bento Sterman Ferraz, Flávio Vieira Meirelles, Júlio César de Carvalho Balieiro, Joanir Pereira Eler, Luís Gustavo Girardi Figueiredo, Gerson Barreto Mourão
Published September 6, 2005
Genet. Mol. Res. 4 (3): 496-505 (2005)
About the Authors
Erica Perez Marson, José Bento Sterman Ferraz, Flávio Vieira Meirelles, Júlio César de Carvalho Balieiro, Joanir Pereira Eler, Luís Gustavo Girardi Figueiredo, Gerson Barreto Mourão
Corresponding author
E.P. Marson
Email: epmarson@usp.br
ABSTRACT
A population of 370 European-Zebu composite beef heifers, consisting of six different breed compositions (A-F), were characterized genetically, using RFLP markers of luteinizing hormone receptor (LHR) and follicle-stimulating hormone receptor (FSHR) genes. Our objectives were to genetically characterize this population and to determine the structure and the genetic variability of this hybrid herd. The genotypes were determined through PCR, followed by digestion with restriction endonucleases. The PCR-RFLP analysis made it possible to identify the LHR and FSHR genotypes, as well as to characterize the degree of heterozygosis, which was high for all of the breed compositions, for both loci, except for two combinations for LHR (B and C). The observed heterozygosity (Ho ) was lower than the expected heterozygosity (He ) for compositions C (for LHR) and A and D (for FSHR); however, for the population as a whole, Ho was above He (with a mean of 57 versus 46%, respectively), reflecting the elevated genetic variability in this population and also the informative value of the RFLP mers, which could be useful for population genetic characterization studies. The analysis of the degree of genetic structure of this population, estimated by the Nei’s statistic, for both loci, indicated an elevated total genetic diversity (HT = 47%), with most of this variability being due to intrapopulational diversity (HS = 46%), with a low degree of genetic differentiation among the six breed compositions (GST = 1.2%). The estimates generated by the Wright’s F statistic indicated a non-endogamic population, with excess heterozygotes (FIT = -0.22), which was also observed at the intrapopulational level (FIS = -0.23). The results gave evidence that the genetic selection applied to this European-Zebu composite population did not affect the expected high genetic variability for this type of crossbreeding, which makes it possible to use these animals to obtain economically valuable productive and reproductive traits.
Key words: Composite beef cattle, RFLP, Genetic characterization, DNA.