Relationship between the slaughter yield of intensively fattened lambs and genomic loci in sheep breeds raised in Latvia

Improving the economic efficiency of sheep farming depends significantly on increasing animal productivity. In meat sheep breeds, one key productivity indicator is slaughter yield, a trait influenced by numerous biological parameters and regulated by multiple genes involved in diverse molecular pathways. Genetic variation in these pathways can be utilized through molecular marker-assisted selection, especially when markers show significant associations within specific populations.

This study aimed to identify potential molecular markers associated with slaughter yield in intensively fattened lambs of sheep breeds raised in Latvia. A total of 160 lambs (59.5% Latvian Dark-Head breed) from the most common local breeds were included in a controlled fattening program. Slaughter yield (%) was measured (44.45±2.52%) at age 149.65±14.26 days, and genotyping of 57 SNPs across eight candidate genes was conducted. Association and regression analyses were performed to assess the relationship between genotypes and slaughter yield.

Among the analyzed SNPs, 23 (40.35%) showed statistically significant associations with slaughter yield in the Latvian sheep population. The strongest associations were found for two SNPs in the UPC2 gene (rs412180048 A>G and rs405808821 C>T) and two in the MTOR gene (rs419418343 C>T and rs160776285 T>C). In both UPC2 SNPs, the highest slaughter yields were observed in lambs homozygous for the common allele, although this genotype was rare in the Latvian population. In the case of MTOR, the highest yield was found in both homozygous common and heterozygous genotypes, which were present in only 25% of the sampled animals.

These results suggest that SNPs in UPC2 and MTOR genes have strong potential as molecular markers for improving slaughter yield through marker-assisted selection in Latvian sheep breeding programs.

Acknowledgements: This research was supported by the Latvian Council of Science (LZP-2021/1-0489) and the University of Latvia Postdoctoral Project No. 1.1.1.9/LZP/1/24/027 “Genetic markers as a basis for the excellence of carcass quality traits in the Latvian dark-headed sheep breed”.