Membrance Material Isolated from Milk of Mastitic and Normal Cows

Abstract

The appearance of two types of milk membrane material after high-speed centrifugation of milk was followed in a group of disease-free cows exposed to pathogenic organisms. Milk membrane appeared as a fluffy layer in those quarters which became infected. In uninfected quarters only, a thin layer of material covering the sedimented casein was observed. Acid phosphatase activity was recorded in both types of material but was higher in the fluffy layers from mastitic milk. In most cases the fluffy layer disappeared following treatment of infected quarters with antibiotic. Acrylamide gel electrophoresis patterns of the proteins from the membrane material of normal and mastitic milk were similar and showed some major milk fat globule membrane proteins. Morphological examination of the two types of milk membrane revealed that they contained the same structural elements but in different proportions. The material apparently originated from leukocytes, mammary gland cells, and milk fat globule membrane. Mastitic milk membrane contained a larger proportion of mammary gland cell and leukocyte-derived material than normal milk membrane.