Identificação de QTL nos cromossomos 10, 11 e 12 associados ao estresse calórico em bovinos

• Autor(a) principal: Columbiano, Virginia de Souza
• Data de Publicação: 2007
• Tipo de documento: Dissertação
• Idioma: por
• Título da fonte: LOCUS Repositório Institucional da UFV
• Texto Completo: http://locus.ufv.br/handle/123456789/4813
• topic: Bovino; Melhoramento genético; Fatores climáticos; Locos de caracteres quantitativos; Marcadores genéticos; Dairy cattle; Breeding; Climate aspects; Quantitative traits locos; Genetic markers; CNPQ::CIENCIAS AGRARIAS::ZOOTECNIA::GENETICA E MELHORAMENTO DOS ANIMAIS DOMESTICOS

Heat stress impacts greatly animal production systems on tropical regions causing economical losses and affects milk production, meat production, physiology, reproduction, calf mortality and utter health. One way to reduce these losses is to use the genetic variation between Bos taurus and Bos indicus breeds for heat tolerance coupled with linked molecular markers as an auxiliary tool in breeding programs to produce thermotolerant and more productive animals. This work aimed to map genomic regions related to heat stress on chromosomes 10, 11 and 12 in a F2 population derived from Holstein x Gyr crosses. The following traits were evaluated: variation of rectal temperature after heat stress (DifTR), variation of skin temperature after heat stress (DifTPele), variation on the rate of respiratory movements after heat stress (DifMR), sweating rate after heat stress (TxSud), fur density (DensidPêlo), fur length (CompPêlo), coat length (CompCapa) and coat thickness (EspessCapa). All traits were evaluated in two seasons (wet-warm and dry-cool) and analyzed separatedly. A total of 17 microsatellite loci were genotyped on 480 animals (31 parents, 73 F1 and 376 F2). Association analysis indicated a QTL (p<0,01) for CompPêlo located at the position 72 cM on chromosome 10 for data collected on the wet-warm season. On chromosome 11 it was found an indication of QTL (p<0,05) for TxSud located at the position 0 cM for data collected on the drycool season. On chromosome 12 it was also found an indication of QTL (p<0,05) for CompPêlo located at the position 28 cM for data collected on the dry-cool season. The strategy of genome scan with microsatellite markers was shown to be effective to identify QTL regions related to heat tolerance traits. These mapped regions need to be refined with additional markers to better understand the QTL effects and to identify candidate genes responsible for the effects on these traits.