Sustainable livestock production requires the development and implementation of non-toxic natural methods for disease control and modification of production including vaccination and breeding of genetically superior animals. Multi-component vaccines that enable several vaccines to be incorporated into a single injection would help maximise production. However, some of the most advanced livestock vaccines in Australia have been found to be limited by competition for immune response between components (antigens) in the vaccines. As the number of components increases in a single vaccine, functional immunity to each component is reduced. This small project aims to investigate the occurrence of antigenic competition in vaccinated small ruminants in India and to identify differences and similarities in responses of sheep and goats. It will also define the steps in the immune response that cause the phenomenon of antigenic competition and will look for ways to overcome it.