Abstract: Embodiments of this invention include lipid-based immunogenic compositions (adjuvants or carriers) useful for oral or gastrointestinal administration for improving mucosal immune responses in animals vaccinated for a variety of bacterial infections. In certain embodiments, lipid compositions of this invention include a mixture of fatty acids having different chain lengths, thereby providing desired physico-chemical properties. When a bacterial antigen is mixed with a lipid-based adjuvant or carrier, the resulting composition elicits improved mucosal immune responses and thereby decreases infections and sequellae of disease caused by Chlamydia or Helicobacter.