Mapeamento de QTL para características de produção de leite no cromossomo 6 em rebanhos Gir Leiteiro

• Autor(a) principal: Silva, Ariosto Ardila
• Data de Publicação: 2009
• Tipo de documento: Tese
• Idioma: por
• Título da fonte: LOCUS Repositório Institucional da UFV
• Texto Completo: http://locus.ufv.br/handle/123456789/1287
• topic: QTL; Microssatélites; QTL; Microsatellites; CNPQ::CIENCIAS AGRARIAS::ZOOTECNIA::GENETICA E MELHORAMENTO DOS ANIMAIS DOMESTICOS

In tropical countries, Gyr (Bos indicus) breed is very important due to their heat and parasite tolerance, and essential to girolando cattle formation (5/8 Holstein, 3/8 Gyr). Dairy Gyr is much more adapted to climate and economical traits in Brazil and with crucial qualities for a good milk production on the tropics. The dairy Gyr was the first Zebu breed in Brazil and the world with a program of genetic evaluation since 1985, through of progeny tested sires. This study was done with the objective of identifying QTL on chromosome 6 for nine milk production characteristics through daughters design. Fourteen families of sire Gyr with 657 daughters were analyzed using 27 microsatellite markers. In the analysis across 14 families and within the largest significant families, four-QTL were detects for milk yield, fat yield, fat percentage and total solids yield, at the 1% chromosome-wide. With families three and nine, a QTL was detected for milk yield, in the position 46 cM, near BMS2508 marker and with F = 9,64; with family three, a QTL was detected for fat yield, in the position 48 cM, near DIK4382 marker and with F = 16,61; the QTL for fat percentage was detected with families three and four, in the position 56 cM, near DIK4482 marker and with F = 15,18; and for total solids percentage, a QTL was detected with the families three and four, in the position 57 cM and with F = 7,61. With the significant families, QTL that affects protein yield, lactose yield and total solids yield, were mapping at the 5% chromosome-wide. The central autosomal region of the chromosome is very problematic for interpretation and localization of data, for possible QTL interference and can present pleiotropic QTL effects. In this study the majority of the QTL were detected in this region. In the middle region of BTA6 next to marker BM143 (53cM) between genes ABCG2 and LAPs are located 6 genes including Osteopontin (OPN), PPARGC1A, FAM13A1 and PKD2. Different groups were investigated the possible association between genes in this region and the milk production characteristics in dairy cattle. The analysis showed the localization of the QTL near this region, which can slow the identification of the candidate genes. The path to solve this problem is doing genetic mapping with precision using molecular markers SNP (Single Nucleotide Polymorphisms).