Mammary Transcriptome Profile during Peak and Late Lactation Reveals Differentially Expression Genes Related to Inflammation and Immunity in Chinese Holstein.

Ziyin Han,Yongliang Fan,Juan J Loor,Yi Yang,Zhangping Yang

doi:10.3390/ani10030510

Abstract

Somatic cell count (SCC) in milk is widely used in the dairy industry, as an indicator of the health of mammary gland. While the SCC of dairy cattle was higher in late lactation than in peak lactation, its association with gene expressions of mammary gland were largely unknown. In this study, a transcriptomic sequencing approach and bioinformatics analysis were used to investigate the differential expressed genes (DEGs) associated with inflammation and immunity between peak and late periods of lactation in Chinese Holstein. A total of 446 DEGs (padj < 0.05 and fold change >2) were identified, 50 of which belonged to seven pathways and five terms related to inflammation and immunity. Our data suggested that the activation of nuclear transcription factor-κB (NF-κB) pathway and Toll-like receptor signaling pathway caused inflammatory response, and the activation of chemokine signaling pathway and cytokine-cytokine receptor interaction signaling pathway caused a protective immune response to ensure dairy cows health during late lactation. Our findings deepen the understanding of the molecular mechanism and physiological functions of mammary inflammation in Chinese Holstein during late lactation.

Highlights

The somatic cell count (SCC) referred to as the total number of somatic cells per milliliter of milk is widely used to measure the health status of dairy cows and the quality of milk [1]
Escherichia coli was identified in the positive cultures
The results showed genes expression trends wereconsistent consistentbetween betweensequencing sequencing data data and thatthat the the genes expression trends were that the thethe genes expression trends were between sequencing results

Summary

Introduction

The somatic cell count (SCC) referred to as the total number of somatic cells per milliliter of milk is widely used to measure the health status of dairy cows and the quality of milk [1]. The quality and yield of milk was negatively associated with SCC [2], which is an important indicator of clinical and subclinical bovine mastitis. The United States stipulates that SCC in bovine milk must be less than. 400,000/mL, and China’s standard is that SCC in bovine milk must be less than 500,000/mL [3,4]. Previous studies have focused on the interfering factors of SCC and its association with the quality and yield of milk [2,5,6]. Several studies have demonstrated that the SCC was higher in late lactation than that in peak lactation [7,8,9,10,11]. The autoimmune reaction and the innate immune response of dairy cattle protect them from mastitis during lactation, especially in the late stage [12], the changes in gene expression level in mammary gland tissue at different stages of lactation are largely unknown

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