Scientists have identified nearly 300 proteins in serum and as advances are made in analytical techniques, at least double that number are likely to be discovered. Among these proteins are certain ‘bioactive proteins’ that provide beneficial functions such as antibacterial and anti-inflammatory effects and improved intestinal barrier function. These bioactive proteins include immunoglobulins, albumin, transferrin, bioactive peptides and growth factors, and can have a positive impact on mucosal surfaces (such as the lining of the intestine) when supplemented in diets for horses.