Genomewide association study for carcass and meat quality traits in Italian Simmental

Genetic improvement of meat traits in cattle is usually carried out on growth performances and muscularity score of young bulls in performance test stations. In Italian Simmental (IS), genetic and genomic estimated breeding values for meat and milk traits are combined in a dual-purpose selection index. However, carcass and nutritional quality traits are excluded because expensive to measure and recorded after slaughtering. Our objective was to search for genomic variants associated with technological and nutritional quality of meat. To this aim, 119 IS young bulls were genotyped using GGP-HD v.2–150K that simultaneously interro gate about 139K single nucleotide polymorphisms (SNP). After data editing, 117 calves and 120,188 SNPs on 29 chromosomes (chr) were analysed. The animals were unselected young bulls at performance test station at Fiume Veneto (Italy) slaughtered between 16 and 18 month of age. After measuring 7 carcass traits, longissimus thoracis m. was sampled and analysed for assessing meat quality (12 traits) and fatty acid composition (31 Traits). The traits examined were live weight at slaughterhouse (LW), Carcass Yield (CY, %) and centesimal composition, SEUROP, pH (48 h), Colour (48h, L*, a*, b*, c and h), cooking loss (CL7) and Warner-Bratzler share force 7 d post-slaughtering (WB7), the profile of 26 fatty acid (%) and their relevant sum and ratio (5 traits). Genome-wide association study (GWAS) were conducted using GenABEL package implemented in R software (v. 3.6.1) and candidate genes in QTL regions ± 250kb interval were retrieved from Genome Browser (https://genome.ucsc.edu/). LW and CY [page 184] [Ital J Anim Sci vol.22:s1, 2023] 25th Congress of Animal Science and Production Association were 664.8±42.6 kg and 56±2.2%. GWAS allows to detect QTL regions in 24/50 analysed traits and to suggest 238 candidate genes on 21 chr(s). The SNPs associated to pH, colour (b*, c) and fat% allows to target 34 genes. The fatty acid composition traits harboured the largest number of QTL. In summary, 196 genes in QTL region were retrieved for saturated, mono/poly-un saturated fatty acids and relevant sum/ratios. SNP genotypes close to the FANS gene (chr19) were associated C14:0 and 5 genes located on BTA5 were related to 4 poly-unsaturated fatty acid (C20:2w6, C20:3w6, C20:4w6 and C22:4w6). In conclusion, GWAS allowed to identify a number of QTL region harbouring gene pos sibly affecting meat nutritional quality