Effect of Heat Treating Colostrum
The research team at Penn State University compared the effects of heat treating colostrum using three qualities of colostrum (high 98g/L IgG's, medium 66g/L, low 52g/L). Note that even their lowest quality was above the industry standard of 50g/L for "adequate" colostrum quality.
They varied the heat treatment time - one half was heat-treated for 30 minutes at 60C while the other half was heat-treated for 60 minutes.
Heat treating decreased IgG concentrations but only by a small percentage. An average of 9 percent loss was present when heat-treated for 30 minutes and average loss of 12 percent when heat-treated for 60 minutes. Thus, even when these losses were subtracted from medium and high quality colostrum their values were well above the 50g/L industry threshold.
Heat treating significantly decreased the bacteria both at 30 and 60 minutes of treatment with the longer treatment eliminating nearly all the bacteria.
Further, heat-treating significantly improved the transfer rate of antibodies into the calves blood.
Now. they also confirmed that as colostrum quality went up the total number of antibodies in calves went up - feed more, and more end up in the blood. [By the way, they fed 4 quarts to these calves within 60 to 90 minutes after birth.]
So, feeding high quality colostrum in significant volume shortly after birth actually works! Now, at the same time the percentage of antibodies fed compared to the volume that make it into the blood does take a hit with lots of high quality colostrum. The efficiency of absorption does go down when the gut is flooded with a bizzion (is that a number?) IgG's.
From a practical point of view, I am aiming for the highest IgG level practical calf side on farm. The IgG's not absorbed can be high quality protein for the calf to digest.
Reference: Saldana. D.J., and Others "Effect of different heating times of high-, medium, and low-quality colostrum on immunoglobulin G absorption in dairy calves." Journal of Dairy Science 102:23068-2074 March 2019