The incidence of infection of the udder in a herd of cows over a period of years.
D000818:Animals; D002417:Cattle; D002418:Cattle Diseases / Q000453:epidemiology*; D005260:Female; D008321:Mammary Glands, Animal / Q000382:microbiology*; D013203:Staphylococcal Infections / Q000453:epidemiology / Q000662:veterinary*; D013290:Streptococcal Infections / Q000453:epidemiology / Q000662:veterinary*