Colostral constituents including immunoglobulins in the first three milkings postpartum.

Colostral changes in immunoglobulin (IgG), dry matter, ash, total protein, and whey protein were studied over the first three milkings postpartum. Immunoglobulin IgG concentration in colostrum from Holstein cows beginning their first, second, or third lactation was similar. However, older animals had more IgG in colostrum. Its rate of disappearance from colostrum was greater in younger animals. Dry matter, ash, total protein, and whey protein concentrations decreased from the first to the third milking (24 h) postpartum. Protein was the most variable constituent between cows at the same postpartum time.