Effects of frequent teat stimulation on antimicrobial component production in mammary glands of lactating goats

Various antimicrobial components, such as lactoferrin, S100 calcium-binding protein A7 (S100A7), and IgA, produced by epithelial cells and leukocytes in lactating mammary glands are important for host defense against invading pathogens. Increase in milking frequency enhances milk yield in ruminants and implies an increase in frequency of teat stimulation. However, the influence of frequent teat stimulation on the production of antimicrobial components remains unclear. In this study, we investigated the effect of frequent teat stimulation, with and without milk removal, on the lactoferrin, S100A7, and IgA concentrations in milk of lactating Shiba goats in Japan. The lactoferrin, S100A7, and IgA concentrations in milk were measured using ELISA. We found that lactoferrin concentration decreased by frequent teat stimulation with milk removal, although concentrations of IgA and S100A7 increased. Frequent teat stimulation without milk removal also altered the lactoferrin, IgA, and S100A7 concentrations. Furthermore, frequent teat stimulation increased IL-22 concentration, which has been reported to upregulate S100A7 production in cultured human keratinocytes. Thus, these findings indicate that frequent teat stimulation, with or without milk removal, affects antimicrobial components in milk and may be useful for the prevention and treatment of mastitis in ruminants.