Relationships between novel nucleotide variants within the colony-stimulating factor 1 receptor (CSF1R) gene and mastitis indicators in sheep.

Colony-stimulating factor 1 receptor (CSF1R) plays an important role in the process of innate immunity and inflammation, thus it was hypothesized that the CSF1R gene might affect the occurrence of mammalian mastitis. The purpose of this study was to investigate the association between nucleotide variations of CSF1R gene and mastitis in Australian white sheep (AUWs). Two indel variants (Intron5-27 bp and Intron5-22 bp) within the CSF1R gene have been found in AUWs. The Chi-square test for different mastitis symptoms demonstrated that individuals without symptoms of mastitis had higher 'I' allele frequencies and 'II' genotype frequencies (p < 0.01). We found strong correlation between mastitis and lactation score through Pearson correlation analysis. Therefore, we also analyzed the relationship between the two indel loci and lactation, we found that the lactation ability of individuals with type II was stronger than that of DD genotype at the Intron5-22 bp (p < 0.05). Additionally, we found that the combined genotype of the two loci was significantly associated with mastitis (p < 0.01). These findings indicated that CSF1R mutations were significantly associated with mastitis, and could affect lactation performance, suggesting that two deletion sites could be used as the effective molecular markers against mastitis in sheep breeding.