Expression analysis of candidate genes for chronic subclinical mastitis in Norwegian Red cattle

摘要

Chronic subclinical mastitis (SCM) is characterizedby a long-term inflammation in the udder with highsomatic cell count (SCC) in milk. Previously, severalnovel alternative SCM traits for Norwegian Red (NR)cattle have been defined to improve breeding strategiesagainst chronic SCM. Quantitative trait loci andcandidate genes affecting chronic SCM in NR havebeen identified. The aim of this study was to analyzethe expression profiles of 14 selected candidate genes(RAD17, ACOT2, ACOT4, FOS, CXCL1, CXCL8,CCNB1, CDK7, TGFB3, SEL1L, STAT4, C6, GLI2,and SLC18A2). Twenty healthy NR cows with officialgenomic estimated breeding values (GEBV) for lactationaverage somatic cell scores (LSCS) were selected.Ten cows had high GEBV for LSCS (cows with lowprobability to have high SCC in milk during lactation)and 10 cows had low GEBV for LSCS (cows with highprobability of having high SCC in milk). We isolatedRNA from unstimulated peripheral blood mononuclearcells from these. Two out of the 14 analyzed genesshowed significantly different results between groups.The group with high GEBV for LSCS displayed significantlyhigher expression of the CXCL1 gene than thelow GEBV group. Grouping by lactation stage revealedsignificant differential expression of the FOS gene, withhigher expression in early lactation (2–3 mo after calving)compared with late lactation (7–8 mo after calving).In addition, flow cytometry was performed on theperipheral blood mononuclear cells samples to analyzeif number and type of isolated cells influenced the geneexpression in the groups. The results in the currentstudy provide identified genes that can be considered aspossible candidate genes for chronic SCM in NR cows.