Timing Blood Draw for Checking on Passive Transfer of Immunity
It is possible to get too eager to draw blood for checking on passive transfer of immunity from colostrum feeding.
With my own calves I had a routine of collecting blood the second day they were with me. All the calves born in the previous 24 hours were delivered to my calf hutches late every morning. They then received a PM milk feeding that same day and another feeding the next morning.
After cleaning up all the milk feeding equipment I went back to the calves to feed calf starter grain. It was convenient time to draw blood on the new arrivals from the previous day. All of them had at least 24 hours since they were fed colostrum. Blood antibodies levels should have peaked.
What can go wrong?
Not waiting at least 24 hours between colostrum feeding and drawing blood.
Let's say I drew blood every afternoon, 1 or 2PM. What if a calf was fed colostrum at 6AM, moved to her hutch at 11AM and I drew blood the same afternoon? The antibodies would not have a chance to fully migrate into the blood in that short time between 6AM and 2PM. Test results would be invalid.
The resource, Passive Transfer of Immunity: When to Test, goes over all these points. You can go to it by clicking HERE.