Bovine Immuno-gamma globulin Purified, gamma globulin preparations are isolated from pooled normal serum by fractionation and ion-exchange or gel filtration chromatography. Gamma globulin preparations are provided as lyophilized powders. Purity levels are 67% gamma globulin as analyzed by SDS-PAGE. These preparations are especially useful as a co-precipitant in RIA methods employing polyethylene glycol or ammonium sulfate precipitation steps. The gamma globulin preparations reconstitute to pH 7.0?0.2.