Mastitis continues to be one of the top two health issues (lameness is the first) in US dairy farms, and one of the main culling reasons. Mastitis is the result of either contagious or environmental bacteria causing inflammation in the udder. Contagious bacteria are spread from a cow with an infected udder to a healthy cow. Environmental bacteria come from the cow’s environment (bedding, soil, manure, etc.) and thus are highly influenced by management practices.