Fig. 1

Identification of S. aureus isolated from milk samples from Holstein cows. a Workflow of sample selection. A total of 38 mother-daughter pairs were selected from 1,200 lactating dairy cattle according to pedigree and SCC records. After S. aureus identification from milk samples, four S. aureus-positive and four S. aureus-negative pairs were used for subsequent studies. b Specific PCR and electrophoresis map of the S. aureus thermonuclease (nuc) gene (279 bp). SA: abbreviation of S. aureus. +: S. aureus-positive control; −: S. aureus-negative control. SM: S. aureus mastitis mother; HM: healthy mother; SMD: S. aureus mastitis daughter; HMD: healthy daughter. c Sequence alignment of partial nuc gene. The upper lines were amplified from samples collected from the cows’ milk; the lower line is nuc sequence amplified from one of the S. aureus-positive samples. Identity = 95.68%