Transcriptome profiling of four candidate milk genes in milk and tissue samples of temperate and tropical cattle.

The expression of four genes involved in milk regulation and production in bovine milk and tissue samples profiled using quantitative PCR to identify differential gene expression. Our goal focussed on the differential mRNA expression of milk genes (KCN, PRL, BLG and PIT-1) in milk samples and different tissues from four different breeds of ecologically adapted and geographically separated cattle species. The mRNA expression identified the four milk genes under studied most upregulated in mammary gland and milk samples as compared with other tissues. The expression of PIT-1 gene in the brain identified to have influenced the expression of PRL and K-CN in the mammary and milk samples. Among the four genes, PRL had the highest mRNA expression (144.19-fold change) in Holstein followed by K-CN with 100.89-fold change, while the smallest relative expression for most genes in this study are in the range from 0.79 to 7.35-fold difference. White Fulani cattle was identified to have a higher expression for K-CN, PRL and BLG compared with Angus and Ndama cattle, while Holstein cattle is on top of the list on the basis of the gene expression and gene regulation for all the four genes in this study. Also, White Fulani and Holstein are in the same cluster based on their mRNA expression for milk genes. Our data showed the first evidence of the molecular identification of indigenous White Fulani cattle ofhaving potential for higher milk production.