Westside Enterprises

Trace Minerals and Udder Health

by dr. Noélle Steyn, Westside

Between 2009 and 2015 the Dutch have managed to decrease the use of antibiotics in the dairy sector with 47% (MARAN, 2012, 2016). Interestingly over the same period a reduction in the national average bulk tank somatic cell count (SCC) was also recorded. SCC is often used by veterinarians and farmers as a measure of udder health. Poor udder health affects SCC and milk yield and is correlated with the clinical incidence of mastitis within herds.

Mastitis, lameness, and fertility problems are conditions with a severe economical impact as they lead to poor production and reproduction, as well as increased management costs. These conditions generally require additional veterinary visits and are often treated with the help of antibiotics. With the ongoing pressure to reduce our usage of antibiotics, we should make use of other available resources to improve cow health and to reduce the incidence of these conditions.

Improved nutrition, hygiene, milking routine, management at calving and biosecurity all come to mind. However, for the purpose of this article we will focus on trace mineral nutrition only.

Trace Minerals

The value of supplying a good quality, highly available trace mineral shouldn’t be overlooked. Inclusion of Se, Mn, Cu and Zn, at the correct levels, is required to optimize health and production in lactating and periparturient cows. The transition period is a physiologically stressful time which affects the efficiency of the immune system, making cows more vulnerable to infections such as mastitis and metritis. Trace minerals are required to maintain proper immune function, mostly by acting as antioxidants. By reducing the amount of free radicals, antioxidants protect cells from damage. Free radicals are produced as part of normal physiological processes but production increases during times of increased metabolic demand, such as calving and peak lactation.

Selenium received much attention recently as a shift towards organic selenium yeast was seen in the market. Observed advantages of supplementing dairy cows with adequate organic selenium includes improved antioxidant status, reduction in occurrence and severity of mastitis and metritis cases, decreased udder oedema and fewer retained placentas.

The udder

If we want to prevent mastitis we should understand how the udder defence mechanisms work and what they require to function optimally. The first line of defence is the teat canal. The teat canal is lined by keratin which also has antibacterial properties. The teat canal can be thought of as a barrier to prevent bacteria from entering the udder. The second line of defence is the white blood cells (WBC), within the udder. WBCs remove bacteria by phagocytosis (ingesting bacteria) and killing bacteria inside the WBC. The amount of WBC and the ability of these cells to kill bacteria is influenced by trace mineral status.

Se, Cu and Zn

Selenium and vitamin E status will determine how many WBC reach the site of infection, in this case the mammary gland. Copper status then affects the number of bacteria that can be killed, through a process known as phagocytosis. Phagocytosis can be thought of as bacteria being eaten by WBCs, once inside the WBC a complex reaction takes place to kill the bacteria. During this killing reaction various enzymes, that require zinc and copper, remove harmful by-products, and convert them to less harmful products. Selenium is once again important in this final step where hydrogen peroxide, which can cause oxidative damage to cells, is converted to water. Zinc is also required to form the keratin lining in the teat canal. If we consider the function of these three elements within the udder, the importance of adequate trace mineral supplementation is evident.