Antibody absorption

From this graph, you can see the importance of getting the colostrum into the calf as soon as possible. By 24 hours old, the calf’s ability to absorb antibodies has rapidly declined. This decline starts 30 minutes after birth which stresses the importance of feeding calves colostrum as soon as they are born. (graph source: Penn State)

The mighty immune system

This graph shows how long the passive immunity from colostrum lasts when the calf is given the correct quality and quantity of colostrum. By day 14 the calf has entered into the risk period for sickness. At this time the calf is starting to activate its own immune system rather than the immunity gained from the colostrum. (graph source: Penn State)