The Bacterial Flora of Normal Cows Udder

The data presented in this bulletin represent studies carried on over a period of two years. The investigation was divided into two main parts as follows: Part I. Studies of the number of bacteria normally inhabiting the udder. Under this division were included total counts, distribution among the quarters, relation of bacterial counts to cell counts, relation of bacterial counts to the reduction of methylene blue, effect of age, stage of lactation, comparison of different portions of the milking and bacterial counts of colostrum. Part II. Studies of the characteristics of udder bacteria together with the type of fermentation they produce in milk. Under this division were included a study of types of total acidity produced in milk by these bacteria, amounts and kinds of volatile acids produced, action of udder micrococci on the proteins of milk, effect of germicidal activity on udder organisms compared with other types, thermal death point of these bacteria and odors and flavors produced in the milk