There’s increasing recognition dairy cattle nutrition has an impact on udder health and, subsequently, milk quality. As producers and their advisors meet in the conference room (or kitchen), the conversation should lead to a better understanding of this relationship.
By Dr. Mike Socha
As somatic cell count (SCC) limits become more stringent, producers continue to look for opportunities to improve milk quality. The role of trace mineral nutrition in lowering SCC is one area receiving renewed interest, as research is well-documented when considering the positive impact improved trace mineral status has on mammary health and immune competence. Dairy producers and their nutritionists have many things to consider as they evaluate solutions to improve milk quality.
1) Which trace minerals are important?
Zinc, copper, manganese and selenium each play critical roles in skin and mammary health, somatic cell count function and disease resistance (immunity). For example, 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.
• Zinc helps maintain the health and integrity of skin due to its role in cellular repair and replacement. It also plays a critical role in formation of the keratin plug in the teat canal, which traps bacteria and prevents it from moving up into the mammary gland.
• Copper affects the killing ability of white blood cells such as neutrophils (somatic cells) to kill pathogens. 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 the highest concentration 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 IM bacterial challenge and increased cellular kill of ingested bacteria by neutrophils.
Ask your nutritionist to monitor the levels of each mineral being fed, and determine whether the source of each trace mineral is highly bioavailable (easily absorbed). Quality and performance do matter, and not all trace mineral products are the same.
2) When is trace mineral supplementation most effective?
In a summary of 14 trials, research showed feeding a combination of highly bioavailable complexed zinc, manganese, copper and cobalt, beginning in the dry period and continuing through lactation decreased SCC by 25%. In comparison, in the trials when the same complexed trace minerals were fed only during the lactation period (not pre-partum), SCC only decreased by 8%.
Ask your nutritionist to investigate data on this kind of performance, and discuss how feeding highly available forms of trace minerals during the dry period and throughout lactation can positively impact SCC, mammary health and immune function.
3) What role does stress play in the development of mastitis?
Stress can be a major player in the development of mastitis. Research at Ohio State University showed the times of greatest risk for mastitis were at dry-off and again at calving, both times of significant stress.
Stress causes an increase in systemic (whole body) inflammation that may put an unnecessary drain on energy reserves and/or on the immune system. When an animal becomes stressed, cortisol is released into the blood stream as a means of reprogramming the animal’s metabolism to fight the stressor. However, that cortisol release ultimately changes the animal’s metabolism and the nutrients needed by the immune system (immune cells) to fight infection are redirected toward escaping the stressful event or maintaining organ function to survive the stress challenge.
Stress also changes how an animal absorbs and retains nutrients, such as trace minerals. Research at Colorado State University demonstrated that the negative effect of stress on absorption and retention of trace minerals in cattle was minimized when trace minerals were fed in the complexed form rather than the ordinary inorganic form. This means that more nutrients will be available to immune cells before and after stressful events to help fight mammary infections.
Ask your nutritionist to evaluate potential cattle stressors on your dairy. Discuss how those stressors might be impacting nutrient metabolism and trace mineral absorption and retention. Discuss what form of trace minerals are being fed to optimize immune function, helping fight mammary infections.
• Dr. Mike Socha is the dairy research team leader at Zinpro Corporation. Contact him via phone: 800-445-6145; or e-mail firstname.lastname@example.org.