Transition Milk - It's Value for Immunity
Based on a sample of 75 Holstein-Friesian cows (pasture-based dairy Ireland, 2nd lactation and greater) samples were collected for the first 5 milkings after colostrum was harvested.
This is how the transition milk samples compared to colostrum (remember we want a refractometer value of 23 or greater or IgG concentration of 50 or greater for first feeding):
Sample No.Samples Median Median
Brix refractometer (%) IgG Concentration(g//L)
Colostrum 68 25.6 99.6
T#1 63 17.8 43.5
T#2 61 12.6 12.5
T#3 59 11.8 5.3
T#4 53 11.4 1.9
T#5 41 11.2 1.8
Colostrum was great stuff - use for first feeding.
First transition milking (T#1) - Still pretty strong for immunity - use for second feeding. In a pinch, this could be used for first feeding. Refractometer does a good job evaluating for immunity potential. And, for localized immunity in the gut for the first week of life this milking has great potential.
Second transition milking (T#2) - to be fed anytime during the first week of life to promote localized immunity in the gut.
3rd - 5th transition milking - not going to confer a great deal in localize immunity in the gut but super for nutritional value - still higher in solids than market milk and packs a nice extra energy boost from higher milk fat content. Refractometer readings less reliable at these low IgG concentrations compared to colostrum.
Reference: Rayburn, M.C. and Others, "Use of a digital refractometer in assessing immunoglobulin G concentrations in colostrum and the first 5 transition milkings in an Irish dairy herd." Journal of Dairy Science 102:7459-7463 August 2019.