This study will investigate the ability of an injectable vaccine to reduce illness and death due to pneumonia in lambs born and raised in a feedlot setting. If the vaccine is effective, it will improve the welfare of the lambs on the farm where the study is conducted, reduce antibiotic usage and costs, and improve profitability for the company that owns the farm. If proven to be effective the study will help to justify the use of this vaccine beyond this population (i.e. other Alberta and Canadian farms) and help to support the use of respiratory vaccines for the livestock industry in general.