Reminder: Heifers Can Have High Quality Colostrum
This week I reviewed research dealing with colostrum composition. One of the reports documented variation of antibody (IgG) concentration by lactation number of the dam. [S.I. Kehoe and Others, "Comparison of immunoglobulin G concentrations in primiparous and multparous bovine colostrum." Professional Animal Scientist 27 (2011):176-180.]
Three central Pennsylvania herds provided the colostrum samples. They were well-manged herds ranging in production from 19,500 to 26,900 rolling herd averages. Colostrum was collected in the range of 2 to 6 hours post calving. Average IgG concentration by lactation showed:
1. All lactations averaged well above the minimum threshold for colostrum to use for first feeding (>50g/l).
2. By lactation the values were:
4th + 113.3g/l
Note that 1st lactation average was far above the 50g/l threshold for first feeding.
"So," you say, "why should I bother to check colostrum for IgG concentration?
At the 4-quart yield level including colostrum from all lactations the lowest IgG value was 20g/l and the highest value was 200g/l. Even on dairies like this roughly one batch of colostrum out of ten had substandard IgG concentrations.
If you are using a Brix refractometer to check colostrum quality you may want to read this resource sheet with tips for getting valid readings. Click HERE for the Brix resource.