Immune system activation at drying off results in liver damage that is still present at the start of lactation
The negative effects of immune system activation and inflammation in dairy cattle
Immune system activation of dairy cows results in an increased glucose utilization by the immune system81, which reduces dry matter intake. This in turn results in a poor transition to lactation, resulting in health problems, poor lactational performance and poor reproduction of a dairy herd.
The mammary gland is known to cause immune system activation, particularly when clinical mastitis occurs after calving, but also during the dry period. Oxidative stress during the dry period of dairy cows can trigger liver damage. The effects of immune system activation during the dry period of dairy cattle can still be present at the start of the subsequent lactation83. The risk of udder infections is high both at the beginning and end of the dry period87 (Figure 1). Hormonal changes and the stress around calving can have a negative impact on the immune system of dairy cows88,89,90. It has been shown that the majority of clinical mastitis cases early in lactation are caused by infections during the dry period91.