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ARS Home » Research » Publications at this Location » Publication #97367
Title: IMMUNE MECHANISMS IN THE BOVINE LACTATING UDDER

Author
item BURVENICH, C - BELGIUM
item DOSOGNE, H - BELGIUM
item HOEBEN, D - BELGIUM
item Guidry, Albert
item Paape, Max

Submitted to: French Society of Buiatrics
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/10/1999
Publication Date: N/A
Citation: N/A

Interpretive Summary: The main cause of mastitis is bacterial invasion and growth within the udder. The incidence of mastitis is usually highest at drying off and around calving. At these times there are many physiological and immunological changes that affect the animal's ability to defend against invading bacteria. At calving white blood cells, the cow's major defense against invading bacteria, are directed towards the uterus. This results in immature cells, that are less effective in destroying bacteria, to be released into the circulation. Also, cells, that produce antibodies that enhance the destruction of bacteria by white blood cells, are greatly impaired. At same time colostrum fosters the growth of bacteria. To what extent these changes are related to defense of the mammary gland remains to be explored. The higher incidence of mastitis at drying off could be attributed to, i.e., decreased ability of mammary secretions to support white blood cell defenses and cessation of the milking process, which eliminates the flushing out of the udder twice a day. However, it is not clear to what extent these various factors put the cow at risk. But, these limiting factors may be overcome by enhancing various aspects of the immune mechanisms via vaccines and factors which modulate the immune system. Also, a better understanding of the influence of the physiology and metabolism of high producing cows could lead to means of improving management conditions so as to improve the cows resistance to bacterial infection of the udder.

Technical Abstract: The main cause of bovine mastitis is bacterial invasion and growth within the udder. The incidence of mastitis is usually highest at drying off and around calving. At calving neutrophils migrate from the circulation to the uterus causing an influx of immature neutrophils from the haemopoetic system. These immature cells are less chemotactic and phagocytic, and produce fewer free radicals. Also, lymphocyte blastogenesis is depressed, IgM production is impaired and helper T-cell function is lost. An increase in IgG1 inhibits the opsonic activity of IgG2 and IgM and Ig binding to neutrophils is decreased. At the same time colostrum fosters the growth of bacteria. To what extent these changes are related to defense of the mammary gland remains to be explored. The higher incidence of mastitis at drying off could be attributed to, i.e., decreased ability of mammary secretions to support phagocytosis and cessation of the milking process. It is not clear to what extent positive energy balance, lower cortisol, somatotrophin and prolactin and high steroid levels in the second half pregnancy have on the mammary defense mechanisms. These limiting factors may be overcome by enhancing various aspects of the immune mechanisms via vaccines and immunomodulators. Also, a better understanding of the influence of the physiology and metabolism of high producing cows could lead to means of improving management conditions so as to improve the cows resistance to bacterial infection of the udder.