Resumo

ARMSTRONG, E. et al. Molecular markers related to marbling in Uruguayan Creole cattle. Arch. zootec. [online]. 2011, vol.60, n.231, pp.707-716. ISSN 1885-4494.  https://dx.doi.org/10.4321/S0004-05922011000300058.

The Uruguayan Creole cattle genetic reserve, located in the department of Rocha, has a high level of genetic variation, as previous studies using polymorphic markers showed. Cattle from this reserve were taken to commercial farms in the North of Uruguay during the 60'. These animals where used in crosses with commercial breeds (Aberdeen Angus, Hereford, Caracú) and zebu (Bos indicus) cattle for meat production. We analyzed a sample of Creole cattle from Rocha and from two crossbred populations from Northern Uruguay (Rivera and Cerro Largo) using three molecular markers associated with marbling: diacyl-glicerol acyl transferase (DGAT1), thyroglobulin (TG) and leptin (LEP). We describe a novel and cost-effective genotyping method based on TETRA-ARMS PCR for LEP polymorphism. The Creole cattle reserve showed higher frequencies of alleles and genotypes associated with low marbling scores in all markers. Both crossbred populations showed the same trend for DGAT1, but higher frequencies for alleles and genotypes associated with higher marbling in TG and LEP. Genetic diversity indexes were low to moderate (minimum He= 0.000 for DGAT1 in Rivera crossbred population; maximum He= 0.632 for TG in Cerro Largo crossbred population). No significant departures from the expected values were detected according to F_IS and Hardy-Weinberg tests, except for one case (TG in Cerro Largo population). F_ST values showed the high genetic similarities between both crossbred populations and their differentiation from the purebred Uruguayan Creole reserve. Genetic introgression of commercial breeds, plus selection objectives tending to increase productivity, had affected the frequencies of the markers analyzed in the crossbred populations. On the other hand, reproductive isolation, absence of artificial selection and the incidence of genetic drift and natural selection had modelled the population parameters of the Uruguayan Creole cattle reserve.

Palavras-chave : Meat quality; Molecular genetics; Genetic resources of Uruguay.

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