Hydrometer test for estimation of immunoglobulin concentration in bovine colostrum.

A practical field method for measuring immunoglobulin concentration in bovine colostrum has been developed from the linear relationship between colostral specific gravity and immunoglobulin concentration. Fourteen colostrums were collected within 24 h postpartum from nursed and unnursed cows and were assayed for specific gravity and major colostral constituents. Additionally, 15 colostrums were collected immediately postpartum prior to suckling and assayed for specific gravity and immunoglobulin concentration. Regression analysis provided an equation to estimate colostral immunoglobulin concentration from the specific gravity of fresh whole colostrum. From this, a colostrometer was developed for practical field use.