RÉSUMÉ
The ASAP1 gene is located in a QTL region for meat production traits and to access the role of the ASAP1 gene, the association between a SNP in this gene and production traits in beef cattle was studied. For this, about 270 steers of reference families of Nelore breed were used. The investigation of marker effects on the traits was performed using a mixed model under the restricted maximum likelihood method. Novel association of a SNP in the ASAP1 gene and shear force measured at 24 h post mortem (P≤0.0083) was described in this population of Nelore cattle. This polymorphism accounted for 1.13% of the total additive variance and 17.51% of total phenotypic variance of the trait, suggesting that this marker could be used in marker assisted selection.
Sujet(s)
Protéines adaptatrices de la transduction du signal/génétique , Bovins/croissance et développement , Qualité alimentaire , Viande/analyse , Développement musculaire , Muscles squelettiques/croissance et développement , Polymorphisme de nucléotide simple , Protéines adaptatrices de la transduction du signal/métabolisme , Adiposité , Allèles , Animaux , Lignées consanguines d'animaux , Brésil , Bovins/métabolisme , Fréquence d'allèle , Études d'associations génétiques/médecine vétérinaire , Introns , Mâle , Phénomènes mécaniques , Muscles squelettiques/composition chimique , Isoformes de protéines/génétique , Isoformes de protéines/métabolisme , Résistance au cisaillement , Graisse sous-cutanée abdominale/composition chimique , Graisse sous-cutanée abdominale/croissance et développementRÉSUMÉ
Canchim is a composite cattle breed developed in Brazil for beef production. One of the breeding objectives is to increase fat deposition. QTLs for fat thickness and/or marbling have been reported on BTA4 and BTA14. The IGFBP3 and DDEF1 genes, mapped to BTA4 and BTA14, respectively, affect adipogenesis. We looked for SNPs in the IGFBP3 and DDEF1 genes that could be associated with backfat thickness in Canchim beef cattle. For SNP identification, sires with the highest accuracy were ranked according to expected breeding value for fat thickness; the 12 extremes (six sires with the highest and six with the lowest expected breeding value for the trait) were chosen. Six regions of the IGFBP3 and 14 regions of the DDEF1 were sequenced using the Sanger method. Nine SNPs were identified in IGFBP3 and 76 in the DDEF1. After an initial analysis, two SNPs were selected to be genotyped for the whole population; these were DDEF1g.279401A>G and IGFBP3c.4394T>C(Trp>Arg). We found a significant effect (P ≤ 0.05) of allele substitution on backfat thickness; however, the IGFBP3 SNP did not significantly affect this trait.