65ª Reunião Anual da SBPC

C. Ciências Biológicas - 8. Genética - 1. Genética Animal

BOTTLENECK IN A BOVINE BREED OF A CONSERVATION HERD (CURRALEIRO PÉ-DURO) AND ABSENCE IN ANOTHER BOVINE BREED OF A COMMERCIAL HERD (TABAPUÃ)

Ednaldo da Silva Filho - Prof. Dr. Instituto de Ciências Agrárias – UFRA, Belém-PA. Marcone Helmer da Silva - Médico Veterinário do Centro Nacional de Primatas, Ananindeua-PA. Luiz Fernando de Souza Rodrigues - Prof. Dr. Instituto de Saúde e Produção Animal – UFRA, Belém-PA. Luiz Marcelo de Lima Pinheiro - Prof. Dr. Instituto de Ciências Naturais – UFRA, Breves-PA. José Elivalto Guimarães Campelo - Prof. Dr. Departamento de Zootecnia – UFPI, Teresina-PI. Marcos Jacob de Oliveira Almeida - Dr. Empresa Brasileira de Pesquisa Agropecuária (Meio-Norte), Teresina-PI.

INTRODUÇÃO:

Brazil is the largest producer of cattle in the world, with about 210 million animals, but about 80% of animals are destined for meat production. The bovines are distributed in two large groups, zebuine and taurine, where stand out Tabapuã and Curraleiro Pé-Duro breeds, respectively. These breeds are excellent gene source, principally for resistence to high temperatures and parasites, moreover, they are excellent producers of meat in the North and Northeast of Brazil. Howover, some studies of genetic diversity these breeds would contribute in the breeding management as in maintenance of genetic variability and in the conservation of bovine breeds, besides other species. The use of genetic markers is an excellent tool for genetic determination and characterization in populations in risk of extinction, being the DNA microsatellites are markers very used in the population studies, disease diagnosis, paternity exclusion and other.

OBJETIVO DO TRABALHO:

To estimate the possible bottlenecks in two herds of meat cattle of Tabapuã breed (commercial herd) and Curraleiro Pé-Duro breed (conservation herd) based in the DNA microsatellite markers of routine in paternity exams.

MÉTODOS:

A total of 120 animals was evaluated, being 60 of Tabapuã breed of a commercial herd from the Nova Leonita Farm at Paragominas-PA city and 60 of Curraleiro Pé-Duro breed of a conservation herd from Experimental Farm of EMBRAPA Meio-Norte at São João do Piauí-PI city. There were collected 5 mL of blood by venous puncture of caudal vein. Extraction DNA were done by phenolic method. PCRs were realized for a set of eleven microsatellite loci that are recommend for paternity exams: BM1818, BM1824, BM2113, ETH10, ETH225, ETH3, INRA023, SPS115, TGLA122, TGLA126 and TGLA227. PCR products were submitted to automated DNA sequencer ABI 3100 (Applied Biosystems) and the fragments were analyzed by Genotyper software (Applied Biosystems). Statistical analyses were performed by Bottleneck software version 1.2.02. for Sign and Wilcoxon tests under Infinite Alleles Model (IAM), Two-Phase Mutation Model (TPM) and Stepwise Mutation Model (SMM). O MODE-SHIFT foi utilizado para representar as proporções das classes alélicas na forma de L.

RESULTADOS E DISCUSSÃO:

Sign test for the Tabapuã breed must have 6.46, 6.56 and 6.5 loci with excess of heterozigosity under IAM, TPM and SMM, respectively, but they showed 10 (P<0.05), 8 (P>0.05) and 6 (P>0.05). In the Curraleiro Pé-Duro, the number of loci with excess of heterozigosity must be 6.41, 6.53 and 6.48 under IAM, TPM and SMM, respectively, but showed 4 (P>0.05), 7 (P>0.05) and 4 (P>0.05). O Wilcoxon test detected mutation-drift equilibrium under IAM and TPM, but some loci with heterozigosity deficiency in both breeds. Different results were found in some bovine breeds from Hungary and and Austrian as some studies made with buffaloes with same objectives this work. The high number of loci with excesso of heterozigosity reflects the management with the maintenance of genetic variability in the Tabapuã breed, the other way around of Curraleiro Pé-Duro that possibly has lost genetic variability and has experienced a bottleneck recently.

CONCLUSÕES:

Tabapuã breed has not heterozigosity deficiency and maintains mutation-drift equilibrium without have bottleneck because it is from a commercial herd with breeding management with sires rotations, this enables the maintence of genetic variability, while that Curraleiro Pé-Duro, being a conservation herd and it is undergoing by reducing the number of animals due to the introduction of new breeds in Northeastern Brazil, it is losing genetic variability, being necessary to insert some sires of other farms, as well as the breeding technologies and animal improve programs to reinforce the Curraleiro Pé-Duro breed as a importance gene source in Brazil.

Palavras-chave: Genetic variability, Microsatellite, Heterozigosity deficiency.