Abstract: Lactoferrin（LF） is one of the defense factor in breast tissue， which plays an important role in bodys resistance to mastitis. The polymorphism of LF gene in 303 Holstein cattle in Ningxia was detected by PCRSSCP， and the effects of LF gene g.4388G>C locus mutation on daily milk yield， milk fat， milk protein percentage and somatic cell score （SCS） were analyzed via general linear model. It was shown that there was a significant relationship between LF gene g.4388 G>C locus mutation and milk yield， milk fat and SCS （P<0.05）. The GC genotype had significantly lower SCS compared with GG and CC genotypes （P<0.01）. Therefore， GC gene as a superior genotype against mastitis would be applied in dairy cattle breeding.

Key words:  Holstein cattle, LF gene, genetic polymorphism, mastitis, milk traits