The process of colostrum production in the udder begins several weeks before calving and stops abruptly when the calf is born. During this time, large amounts of IgG and other immune factors are selectively transferred from the bloodstream of the cow into colostrum. This starts approximately five weeks prior to calving and is maximised in the last two weeks before calving (Maunsell, 2014) when a cow is in the close-up dry cow group. So, the way that the dry cow is managed can greatly impact the quality of colostrum produced. When thinking about the environmental impact the dry period has on colostrum, stress is one of the biggest factors. Stocking rate, feed availability, temperature, group changes, all have an impact on oxidative stress in the cow, which impacts immunity and possibly the quality of colostrum produced.