title: The Small RNA sequencing of mammary gland for Chinese Holstein Cattle: High milk protein percentage phenotype in lactation
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 and subsequently stored at -80 C until RNA isolation.