|Da silva, Marcos|
|Do rosario, Millor|
Submitted to: Genetics and Molecular Biology
Publication Type: Peer reviewed journal
Publication Acceptance Date: 10/24/2006
Publication Date: 3/1/2007
Citation: Miyata, M., Gasparin, G., Coutinho, L.L., Martinez, M.L., Machado, M.A., Da Silva, M.V., Campos, A.L., Sonstegard, T.S., Do Rosario, M.F., Regitano, L.C. 2007. Quantitative trait loci (QTL) mapping for birth weight on bovine chromosome 14. Genetics and Molecular Biology, Vol 30, No.2, pp 364-369. Interpretive Summary: Identification of QTL in tropically adapted, crossbred dairy cattle is an important step to understanding how genetic variation affects production in these diverse environments. The QTL on Chr 14 identified in this study affects birth weight with the allele associated with increased birth weight being derived from Holsteins. Birth weight is an important trait correlated with reproductive efficiency. Selection for lower birth weight in crossbred replacement heifers potentially could led to longer herd life and increased reproductive efficiency. Further map refinement of this QTL is needed before selection of this QTL becomes tenable for genetic improvement.
Technical Abstract: Quantitative Trait Loci (QTL) mapping in livestock allows the identification of genes that determine the genetic variation affecting traits of economic interest. Diverse QTL for growth traits are described in literature, indicating the possibility of QTL mapping for these traits through the scan of bovine chromosomes. In this work, we conducted analysis of QTL for birth weight in a F2 resource population, on bovine chromosome 14 (BTA14), using seven microsatellite markers. Phenotypes were derived from 346 F2 progeny produced from crossing Gyr X Holstein F1 parents. Polymorphism information content was calculated for each marker, where the markers CSSM066 and BMC1207 had the highest and lowest values, 0.824 and 0.385, respectively, reflecting the number of alleles of each marker. Interval analysis to detect QTL for birth weight, revealed the presence of a QTL (P < 0.05) at 1 cM from the centromere, with additive effect of 1.210 +/- 0.438 kg. The QTL allele that increases the weight at birth was inherited from the Holstein parental breed.