When evaluating nutrition solutions to improve milk quality, research has shown that trace mineral nutrition plays a critical role in skin and mammary health, somatic cell count (SCC) function and disease resistance (immunity). In a summary of 14 studies1, research shows that feeding a combination of complexed zinc, manganese, copper and cobalt beginning in the dry period and continuing through lactation decreased SCC by 25 percent. By comparison, in studies where the same complexed trace minerals were fed only during lactation (not pre-partum), SCC only decreased by 8 percent.
Role of key trace minerals
Zinc helps maintain the health and integrity of skin due to its role in cell replication and repair, which is an important part of the natural defense mechanism of the mammary gland. It also plays a critical role in keratin formation, helping entrap bacteria in the teat canal and prevent bacteria from moving up into the mammary gland.
Copper is also considered to have strong effects on the immune system as it is active in neutrophil (somatic cell) production and affects phagocyte (white blood cell) killing ability. It is also required for antibody development and lymphocyte (white blood cell) replication.
Manganese helps improve immune function through enhanced macrophage (white blood cell) killing ability. Macrophages are one of the types of somatic cells released into the mammary gland in high concentrations to help protect against intramammary infections (IMI).
Selenium plays a vital role in immune response and has an associated role with vitamin E in protecting the mammary gland. Selenium also allows for more rapid neutrophil (somatic cell) influx into milk following an IMI bacterial challenge and increased cellular kill of ingested bacteria by neutrophils.
In addition, all four minerals help to protect cellular membranes from damage by removing superoxide radicals (free radicals) from the body. Superoxide radicals are normal by-products of cellular protection against infection. However, these radicals disrupt cellular membranes and cause cellular damage leaving the mammary gland more susceptible to infection, scarring and lost milk production. Trace minerals have fundamental roles in eliciting rapid and effective immune responses to pathogens. Minimizing the incidence, extent and duration of IMI helps decrease milk somatic cell counts, which will ultimately create opportunity for improved dairy profitability.
1 Kellogg et. al., 2003. Prof. Anim. Sci. 19:1; Kincaid and Socha, 2004. Prof. Anim. Sci. 20:66; Ferguson et. al., 2004. J. Dairy Sci. 87 (Suppl.1):117 (Abstr.); Monardes et. al., 2002. J. Dairy Sci. 85 (Suppl.1):265 (Abstr.); Nocek et. al., 2006. J. Dairy Sci. 89:2679; Hackbart et. al., 2008. J. Dairy Sci. 91 (Suppl.1):482 (Abstr.); DeFrain et. al., 2009. Prof. Anim. Sci. 25:709.