Determination of candidate genomic regions associated with growth and ultrasonic carcass traits in ramliç - cross lambs

This study aimed to identify candidate genomic regions associated with growth and ultrasonic carcass traits in Ramlıç and Merino cross lambs at different blood levels (F1, BC1 and BC2). The data for the study were obtained from live weight, body measurements, and ultrasonic carcass traits recorded at different terms from 130 lambs born during the 2021–2022 season at Afyon Kocatepe University, Faculty of Veterinary, Education, Research and Practice Farm. The DNA samples were isolated from the blood of 96 lambs after weaning. Genotypic data were obtained from the DNA samples using the Illumina iScan system with the OvineSNP 50K BeadChip whole genome genotyping kit. The overall least squares - means of the body weight at birth, 60th and 90th days, and weaning were 4.640 ± 0.068, 15.221 ± 0.247, 20.503 ± 0.279, and 27.355 ± 0.342 kg, respectively. The means for body and ultrasound measurements at different terms (60 days, 90 days, and weaning) were as follows: withers height 50.460 ± 0.202 cm, 54.679 ± 0.188 cm, and 58.700 ± 0.221 cm; chest circumference 57.099 ± 0.338 cm, 64.210 ± 0.351 cm, and 72.324 ± 0.341 cm; cannon bone circumference 6.641 ± 0.041 cm, 7.089 ± 0.042 cm, and 7.582 ± 0.047 cm; chest width 13.452 ± 0.098 cm, 15.018 ± 0.098 cm, and 16.949 ± 0.114 cm; rump width 10.025 ± 0.080 cm, 11.432 ± 0.079 cm, and 13.151 ± 0.092 cm; rump height 50.790 ± 0.205 cm, 54.968 ± 0.199 cm, and 59.049 ± 0.227 cm; body length 46.478 ± 0.236 cm, 51.538 ± 0.235 cm, and 56.911 ± 0.261 cm; Musculus longissimus dorsi (MLD) area 5.020 ± 0.090 cm², 6.293 ± 0.094 cm², and 7.718 ± 0.106 cm²; MLD depth 1.745 ± 0.020 cm, 2.010 ± 0.021 cm, and 2.293 ± 0.024 cm; and subcutaneous fat thickness 0.395 ± 0.005 cm, 0.423 ± 0.004 cm, and 0.432 ± 0.008 cm, respectively. Lambda (λ) values found in the study were lower than 0.954 in all GWAS analyses. We identified 116 suggestive (p <0.0001), 22 chromosome-wide (p<0,000026), and one genome-wide significant SNP's (p < 0.000001) in GWAS. The genes near significant SNPs were determined based on the genome version of reference to the Oar_3.1 assembly of the Ovis aries genome in the NCBI database. TMEM108, SOX14, PPP1R37, UBE2U, GRID2, NCAM2, and CAMKMT genes should be focused on considering their potential association with multiple traits due to containing or closing to the significant SNPs of suggestive evidence (p<0.0001) as well.