Genome-Wide Association Study Identifies New Candidate Markers for Somatic Cells Score in a Local Dairy Sheep

Abstract

In the Mediterranean basin countries, the dairy sheep production is usually based on local breeds, which are very well-adapted to their production systems and environments and can indeed guarantee income, employment, and economic viability in areas where production alternatives are scarce or non-existent. Mastitis is still one of the greatest problems affecting commercial milk production. However, genetic evaluation of mastitis is particularly difficult because of its low heritability and the categorical nature of the trait. The aim of this study was to identify genomic regions putatively associated with somatic cells count (SCC) in the local economically important Valle del Belice sheep breed using of deregressed breeding values (DEBV) as response variables. All the samples were genotyped using the Illumina OvineSNP50K BeadChip. Genome-wide association analysis was carried out based on regression of DEBV. A total of eight markers were found to be significantly associated with log-transformed SCC. Several candidate genes associated with SCC were identified related to immunity system and udder conformation. The results can help improving the competitiveness of the local Valle del Belìce breed. Further studies considering a higher sample size or independent population will be needed to confirm our results.

Genome Wide Association Study of Beef Traits in Local Alpine Breed Reveals the Diversity of the Pathways Involved and the Role of Time Stratification

“…Also, the negative genetic correlations occurring between dairy and beef traits make the genetic improvement of both aptitudes in dual-purpose populations far from its optimum ( Frigo et al, 2013 ; Mazza et al, 2016 ; Sartori et al, 2018 ). Moreover, such breeds often present unique characteristics that allow them to adapt to harsher conditions ( Krupová et al, 2016 ; Sutera et al, 2021 ) and better respond to environmental shifts or challenges ( Biscarini et al, 2015 ). Thus, these dual-purpose local breeds represent an unexploited source of diversity for the animal breeding sector and a rare opportunity to conduct GWAS on key economic traits that have not been under excessive specialization.…”

Potential Novel Biomarkers for Mastitis Diagnosis in Sheep

“…The most significant SNP associated with SCC is located in the region of SERP 1 (stress-associated endoplasmic reticulum protein 1). Moreover, these results suggest that individuals with the GG genotypes at rs401598547, CC at rs161717499, and AA at rs403091159, rs422960374, and rs426621433, could be selected to reduce the content of the somatic cell in milk [39]. On the other hand, research conducted by Banos et al [40] confirmed the presence of animal genetic variability in mastitis resistance and identified genomic regions associated with specific mastitis traits in the Chios sheep.…”

“…However, in milk contained >200 × 10 3 /mL somatic cells, they detected 508 bp (DRB1) and 272 (DRB2) alleles more often. Additionally, Sutera et al [39] identified few candidate genes associated with SCC in Valle del Belice sheep related to immunity system and udder conformation. They detected eight significant SNPs (single nucleotide polymorphisms) for SCC located in five different chromosomes, and among these, only one marker reached the genome-wide significance threshold.…”

Genome-Wide Association Study Reveals Additive and Non-Additive Effects on Growth Traits in Duroc Pigs

“…Therefore, in this study, DEBVs obtained from genetic evaluations were used as response variables to improve the detecting power of GWAS. In recent years, much GWAS research has used DEBVs as pseudo-phenotypes, particularly in work on livestock animals [ 31 , 32 ].…”