SHORT COMMUNICATION FTO gene variants are associated with growth and carcass traits in cattle D. Jevsinek Skok*, T. Kunej*, M. Kovac*, S. Malovrh*, K. Potocnik*, N. Petric*, S. Zgur*, P. Dovc* and S. Horvat* † *Department of Animal Science, Biotechnical Faculty, University of Ljubljana, Groblje 3, 1230 Dom zale, Slovenia. † National Institute of Chemistry, Hajdrihova 19, 1001 Ljubljana, Slovenia. Summary An important aim in animal breeding is the improvement of growth and meat quality traits. Previous studies have demonstrated that genetic variants in the fat mass and obesity associated (FTO) gene have a relatively large effect on human obesity as well as on body composition in rodents and, more recently, in livestock. Here, we examined the effects of the FTO gene variants on growth and carcass traits in the Slovenian population of Simmental (SS) and Brown (SB) cattle. To validate and identify new polymorphisms, we used sequencing, PCR-RFLP analysis and TaqMan assays in the SS breed and FTO gene variants data from the Illumina BovineSNP50 v1 array for the SB breed. Sequencing of the eight samples of progeny-tested SS sires detected 108 single nucleotide polymorphisms (SNPs) in the bovine FTO gene. Statistical analyses between growth and carcass traits and 34 FTO polymorphisms revealed significant association of FTO variants with lean meat percentage in both breeds. Additionally, FTO SNPs analyzed in SS cattle were associated with fat percentage, bone weight and live weight at slaughter. The FTO gene can thus be regarded as a candidate gene for the marker-assisted selection programs in our and possibly other populations of cattle. Future studies in cattle might reveal novel roles for the FTO gene in shaping carcass traits in livestock species as well as body composition control in other mammals. Keywords fat mass and obesity associated, haplotype, QTL, single nucleotide polymorphism, single nucleotide polymorphism array Many economically important traits in livestock, such as growth and carcass traits, are under the control of multiple genes. Due to growing consumer demand for products with lower fat content, animals with higher growth rate and better carcass composition are of great significance. In addition, excessive fat deposition has an impact on animal productivity and, not least, on consumers’ health. There- fore, molecular markers associated with these traits would be very useful. For biomarker development, web servers are of great assistance. For example, the current version of the obesity gene atlas includes 1736 fat deposition associated loci, including the FTO gene (Kunej et al. 2012). The FTO gene has been studied extensively since 2007, when it was described as a gene affecting body mass index (BMI) in humans in three independent studies (Dina et al. 2007; Frayling et al. 2007; Loos & Bouchard 2008). These associ- ation studies confirmed that genetic variants in the FTO gene have a relatively large effect on some growth and carcass traits in chickens, pigs, rabbits, sheep and cattle (Table S1). The link between the FTO gene and body composition traits appears to be one of the strongest genotype–phenotype associations detected by genome-wide screening techniques (Barab asi 2007). The objective of this study was to experi- mentally validate the already-published FTO polymorphisms, identify new SNPs and test their associations with growth and carcass traits in the Slovenian population of Simmental (SS) and Brown (SB) cattle (Table S2). To evaluate polymorphisms residing within the FTO gene in the two studied populations, two different approaches were used: (i) sequencing, PCR-RFLP analysis and TaqMan Address for correspondences S. Horvat, PhD, Department of Animal Science, Biotechnical Faculty, University of Ljubljana, Groblje 3, Slovenia and National Institute of Chemistry, Hajdrihova 19, 1001 Ljubljana, Slovenia. E-mail: simon.horvat@bf.uni-lj.si and M. Kovac, PhD, Department of Animal Science, Biotechnical Faculty, University of Ljubljana, Groblje 3, Slovenia. Email: milena.kovac@bf.uni-lj.si Accepted for publication 13 November 2015 doi: 10.1111/age.12403 219 © 2015 Stichting International Foundation for Animal Genetics, 47, 219–222