Mammary gland immunology around parturition. Influence of stress, nutrition and genetics.

Adequate immune functions are essential for the defence against udder infections. Detailed knowledge about the immune response and important defence factors is essential in order to find new ways for the prevention and treatment of udder infections leading to mastitis. Work should be concentrated on ways of minimising the negative influence on immune functions and/or ways of stimulating these functions, especially during periods of immune suppression. A depression of important immune functions has been reported around parturition and there is a higher prevalence of clinical mastitis and other diseases during this period. Immunosuppression is often associated with high levels of glucocorticoids in blood, a common finding around parturition and during stressful conditions. A number of stressors are present around calving, e.g. parturition, onset of lactation and changes in feeding and management regimes. Adequate management including feeding strategies and routines are important for the immune functions. Metabolic stress as well as deficiencies in vitamins and minerals around parturition and during the first month of lactation can have a negative influence on the immune functions and thereby increase the risks for udder infections and mastitis. There seem to be a genetic variability in certain immune functions among periparturient cows. This might indicate a possibility to find markers for genetic selection of individuals with a well-developed immune system without negative effects on milk productivity.