title: Genetic markers of body  composition and carcass quality in grazing Brangus steers.
abstract: The  somatotropic axis is a major regulatory pathway of energy metabolism during  postnatal growth in mammals. Genes involved in this pathway influence many  economically important traits. The association of selected SNPs in these genes  with carcass traits was examined in grazing Brangus steers. These traits  included final live weight, ultrasound backfat thickness (UBFT), rib-eye area,  kidney fat weight, hot carcass weight, and intramuscular fat percentage (%IMF).  Genomic DNA (N = 246) was genotyped for a panel of 15 tag SNPs located in the  growth hormone receptor (GHR), insulin-like growth factor I, insulin-like  growth factor-binding protein 6, pro-melanin-concentrating hormone, suppressor  of cytokine signaling 2, and signal transducer and activator of transcription 6  (STAT6) genes. Allelic and haplotype frequencies were compared with those of a  sample of European breeds (N = 177 steers). Two tag SNPs in the GHR affected  %IMF; one of them (ss86273136) was also strongly associated with UBFT (P <  0.003). The frequency of the most favorable GHR haplotype for %IMF was lower in  Brangus steers. Moreover, the haplotype carrying two unfavorable alleles was  present at a frequency of 31% in this group. Four tag SNPs on STAT6 had a significant  effect on UBFT. One of these, SNP ss115492467, was also associated with %IMF.  The STAT6 haplotype, including all the alleles favoring UBFT, was the most  abundant variant (34%) in the European cattle, while it had a frequency of 14%  in the Brangus steers. The four less favorable variants (absent in the European  cattle) were found at a frequency of 38% in the Brangus steers. These results  support the association of GHR and STAT6 SNP with carcass traits in composite  breeds, such as Brangus, under grazing conditions.
authors.affiliation: Departamento de Producción Animal, Facultad de Ciencias Agrarias, Unidad Integrada Balcarce, Universidad Nacional de Mar del Plata, Balcarce, Argentina.
authors.forename: M C
authors.initials: MC
authors.lastname: Baeza
authors.forename: P M
authors.initials: PM
authors.lastname: Corva
authors.forename: L A
authors.initials: LA
authors.lastname: Soria
authors.forename: G
authors.initials: G
authors.lastname: Rincon
authors.forename: J F
authors.initials: JF
authors.lastname: Medrano
authors.forename: E
authors.initials: E
authors.lastname: Pavan
authors.forename: E L
authors.initials: EL
authors.lastname: Villarreal
authors.forename: A
authors.initials: A
authors.lastname: Schor
authors.forename: L
authors.initials: L
authors.lastname: Melucci
authors.forename: C
authors.initials: C
authors.lastname: Mezzadra
authors.forename: M C
authors.initials: MC
authors.lastname: Miquel
mesh_terms: D000273:Adipose Tissue / Q000737:chemistry; D000483:Alleles; D000818:Animals; D001118:Argentina; D001823:Body Composition / Q000235:genetics*; D001837:Body Weights and Measures; D001947:Breeding; D002417:Cattle / Q000033:anatomy & histology* / Q000235:genetics; D056726:Genetic Association Studies; D005819:Genetic Markers; D005838:Genotype; D006239:Haplotypes; D018969:Insulin-Like Growth Factor Binding Proteins / Q000235:genetics; D007334:Insulin-Like Growth Factor I / Q000235:genetics; D008460:Meat; D018482:Muscle, Skeletal / Q000737:chemistry; D010641:Phenotype; D020641:Polymorphism, Single Nucleotide; D011986:Receptors, Somatotropin / Q000235:genetics; D050800:STAT6 Transcription Factor / Q000235:genetics; D015430:Weight Gain / Q000235:genetics*
chemical_list: D005819:Genetic Markers; D018969:Insulin-Like Growth Factor Binding Proteins; D011986:Receptors, Somatotropin; D050800:STAT6 Transcription Factor; D007334:Insulin-Like Growth Factor I