Factors affecting mammary gland immunity and mastitis susceptibility

College of Veterinary Medicine, Michigan State University, East Lansing, Michigan, USA
Livestock Production Science 05/2005; 98:89-99. DOI: 10.1016/j.livprodsci.2005.10.017

ABSTRACT Dairy cattle are more susceptible to mastitis during the periparturient period. It is well established that the incidence of mastitis with respect to lactation stage are directly related to changes in the composition, magnitude, and efficiency of the mammary gland defense system. There exist numerous genetic, physiological, and environmental factors that can compromise host defense mechanisms during the functional transitions of the mammary gland. For example, physiological stresses associated with rapid differentiation of secretory parenchyma, intense mammary gland growth, and the onset of milk synthesis and secretion are accompanied by a high energy demand and an increased oxygen requirement. This increased oxygen demand augments the production of oxygen-derived reactants, collectively termed reactive oxygen species (ROS). The excessive accumulation of ROS can lead to a condition referred to as oxidant stress that plays a central role in mediating uncontrolled inflammatory responses and causing tissue injury. While the last two decades have seen major progress in understanding the bovine mammary gland defense system and its function in preventing disease, diminished host defenses and increased susceptibility to mastitis continue to be a problem for dairy cattle during transition periods. This paper provides an overview of mammary immunobiology and describes those factors known to influence important mammary gland defenses during the periparturient period.

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Available from: Lorraine M Sordillo, Jun 29, 2015
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    ABSTRACT: The health of dairy animals, particularly the milk-producing mammary glands, is essential to the dairy industry because of the crucial hygienic and economic aspects of ensuring production of high quality milk. Due to its high prevalence, mastitis is considered the most important threat to dairy industry, due to its impacts on animal health and milk production and thus on economic benefits. The MG is protected by several defence mechanisms that prevent microbial penetration and surveillance. However, several factors can attenuate the host immune response (IR), and the possession of various virulence and resistance factors by different mastitis-causing microorganisms greatly limits immune defences and promotes establishment of intramammary infections (IMIs). A comprehensive understanding of MG immunity in both healthy and inflammatory conditions will be an important key to understand the nature of IMIs caused by specific pathogens and greatly contributes to the development of effective control methods and appropriate detection techniques. Consequently, this review aims to provide a detailed overview of antimicrobial defences in the MG under healthy and inflammatory conditions. In this sense, we will focus on pathogen-dependent variations in IRs mounted by the host during IMI and discuss the potential ramifications of these variations.
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