Antibodies: Alternatives to Antibiotics in Improving Growth and Feed Efficiency

The consolidation of poultry since the 1950s largely depended upon two primary management tools: vaccination and antibiotics. These two tools allowed for the prevention of both bacterial and viral infections that could greatly impact poultry raised in large numbers. Antibiotics were also found to improve poultry growth and feed efficiency over 10% when fed below therapeutic levels. Hence, by the late 1950s, the use of antibiotics for improving growth and feed efficiency in consolidated poultry flocks was commonplace. Early in the discovery of antibiotics, the development of resistance was always a concern, particularly in humans’ consuming animal products that were fed antibiotics. While science never conclusively supported this concern, advocate groups persuaded users of poultry products to avoid foods derived from animals fed antibiotics. Scientists studied the theories supporting the mechanism(s) by which antibiotics improve growth. Products to improve animal performance in the absence of antibiotics have included: enzymes, competitive microbial species, precolonization of the gastrointestinal tract with favorable microbial species, and dietary additives that inhibit microbial attachment to the intestinal mucosa. A recent addition to dietary substances that improve growth and feed efficiency in poultry and other species are egg antibodies that specifically target processes involved in the immune regulation of growth. Antibodies to neuropeptides and the rate-limiting enzyme, phospholipase A₂, in eicosanoid synthesis are presented, along with the hypothesized mechanism of action. Evidence suggested that egg antibodies offer a new strategy in improving the efficiency of animal performance.