The Small RNA sequencing of 12 mammary gland for Chinese Holstein Cattle

Milk protein is one of the most important economic traits in the dairy industry. Yet, the miRNA gene regulatory network for the synthesis of milk protein in mammary is poorly understood. In this study, the hypothesis was that miRNAs have potential roles in bovine milk protein production. Using miRNA-seq and RNA-seq, we investigated the miRNAs profiles of mammary glands from 12 Chinese Holstein cows with six cows at peak of lactation and six in non-lactating period, from which three cows were in high and three in low milk protein percentage. Overall design: Based on Dairy Herd Improvement system (DHI) data, the 12 multiparous and healthy mastitis-free Chinese Holstein cattle with three too high and three low phenotypic values for milk protein percentage peak and non-lactation period were chosen from our study, which has been described in the previous study. All mammary samples were retrieved from the 12 candidate Chinese Holstein cows using a biopsy, then placed in liquid nitrogen until RNA isolation.