FYB1 and mastitis: Moreover, when we analyzed introgression in the Nera di Arbus, we found that some of the PNAbv regions harbor QTLs and genes (e.g., C9, FYB, and MYD88) related to somatic cell count and mastitis resistance, traits essential for udder health (Banos et al. 2017; El-Sayed et al. 2025).