An analysis of blood serum total protein values (this dairy blood samples all calves between 36 and 48 hours) showed a significant decline in the proportion of calves above the 5.5 reading during the past three months compared to earlier this year.
However, no permanent record was kept of colostrum quality. The farm protocol was to have each batch (no pooling of colostrum) checked with a Brix refractometer. As the colostrum was bottled it was marked for first-feeding heifers (greater than 22 reading on the Brix) or for bulls or second- feeding for heifers (below 22 on the Brix).
No written record was kept of these readings.
You have already figured out the nature of the problem? Yes, you are correct. The two workers in charge of checking colostrum quality were "too busy" to check every batch after the AM and PM milking of fresh cows.
They checked it visually and said, "This colostrum looks good to me," and marked the bottles according to this visual assessment.
If the colostrum was yellow and thick it was marked for first-feeding heifers. Nope, color doesn't give a valid value of antibody concentration. Nope, thickness or viscosity doesn't give a valid value of antibody concentration.
Visual assessment only works for very bloody colostrum or the thin watery stuff from a sick cow.
What is planned for this dairy? There is now a clipboard in the utility room near where the colostrum is brought for bottling and chilling before it goes into the refrigerator. Yes, you guessed right - each batch is going to be recorded with cow number and the Brix value.
By the way, this dairy periodically samples "as-fed" colostrum for bacteria culturing. After having several high bacteria count samples a year ago and adding a chilling step between collection and refrigeration they consistently have low colostrum bacteria counts.