The calf is born immunocompetent but devoid of immunoglobulins (in cattle, they do not cross the placental barrier). The transfer of passive immunity between the cow and the young calf takes place after birth through colostral drunkenness. But this must be done as early as possible, before the closure of the intestinal barrier (36h).
How to check this immune transfer? Blood sampling on healthy calf between 2 and 6 days, on dry tube or heparinized tube. Measurements made in the laboratory are:
- Total proteins: they are an indicator of the amount of colostrum absorbed by the calf. The value must be greater than 55 g/l.
- Imunoglobulin G (IgG): the concentration must be greater than 10 g/l (predictive value of calf survival, see graph). If the transfer is insufficient, then it is necessary to control the colostrum: sent to the laboratory for assay of IgG and total proteins. The IgG content must be greater than 100 g/l and the total protein greater than 180 g/l. Control of colostrum also allows you to select the best donors: if you want to freeze colostrum as much as it is good!