Using antibiotics to enhance growth in food animals is bringing concerns that antibiotic resistant bacteria, which could affect human health, will emerge. Due to public concern, the industry must look for alternatives. Antibiotics are used to prevent infections in the intestine, which in turn will lead to better utilization of nutrients for growth. Spray-dried plasma (SDP) is being added to the diets of post-weaning piglets to dramatically increase feed intake and growth. SDP is thought to provide immunological protection to the pig, which may prevent immune system activation and allow nutrients to be diverted towards growth. In conclusion, SDP appears to be an acceptable form of replacement for antibiotic growth promoters.