Immunoglobulins are thermolabile. Exposure to temperatures of 75 °C can reduce detectable isolated bovine IgG by 40% in 5 min, and by 100% at 95 °C for 15 s [208] . Heat exposure causes conformational changes in the IgG molecule [212] . Antigen-binding activity of bovine IgG also is reduced after heat treatment [209, 213] . This is consistent with studies that suggest that the antigen-binding region of the immunoglobulin molecule is more thermolabile than the other regions of the molecule [209, 214] . Detectable IgG in colostrum or colostral whey also are reduced by heat treatment, however at a slower rate than for isolated IgG. Thermal protectants such as sugars or glycerol can increase the stability of isolated IgG to heat treatment [208, 215] .