Systemic and mammary inflammation and mammary gland development of Holstein dairy cows around dry-off and calving

作者：Jing Gao, T.N. Marins, J.O.S. Calix, Z. Qi, C.G. Savegnago, A.M. Roper, Moges Woldemeskel, J.K. Bernard, Sha Tao · 发表于：Journal of Dairy Science · 年份：2024 · DOI：10.3168/jds.2024-25279 · 被引用次数：10 · 研究领域：Effects of Environmental Stressors on Livestock、Genetic and phenotypic traits in livestock、Reproductive Physiology in Livestock

This study evaluated systemic and mammary inflammation and the immune cell population and developmental pattern of the mammary gland in Holstein dairy cows transitioning from late lactation to the dry period (LTD, n = 6) and from the dry period to early lactation (DTL, n = 7). All cows were healthy and free of mastitis at enrollment. Mammary biopsies, milk or mammary secretions, and blood samples were collected on d -7, 3, 7, and 15 relative to dry-off and on d -8, 3, 7, and 21 relative to calving. After dry-off, LTD cows had increased circulating concentrations of tumor necrosis factor (TNF)-α, haptoglobin, and fibrinogen, suggesting upregulated inflammation. Protein, SCS, and SNF contents in milk or mammary secretions increased during the early dry period but decreased after calving. In contrast, lactose concentrations in mammary secretions decreased in the early dry period and increased following calving. Skim milk concentrations of TNF-α, IL-10, and haptoglobin increased following dry-off. Consistently, mammary tissue mRNA expression of IL1B and IL10 tended to increase on d 7 and 15 following dry-off, respectively. After calving, mammary alveolar and total cells had higher apoptosis rates. Mammary alveolar, stromal, and total cell proliferation rates peaked on d 7 after dry-off in mammary tissue collected from LTD cows and were greater in the late dry period than early lactation. Mammary mRNA expression of HGF increased on d 7 and 15 after dry-off. Mammary tissue collecte...