Chemical Composition of Mammary Gland During Experimental Mastitis

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Abstract
Water, fat, Na, K, Cl, DNA, RNA, histamine, and glycogen were determined on sheep udder to characterize tissue changes occurring during induction of mastitis with Escherichia coli and Staphylococcus aureus. Inoculations were made on one udder half and chemical changes determined in initial inflammatory stages. One-half to 5 hours after inoculation treated halves showed great increases in size and weight. This resulted in dilution of adipose tissue from 20% of total weight in control to 10% in mastitic glands. Water content increased markedly, from 83 to 88%. The response was very similar in glands from estrus or luteal ewes, while ovariectomized ewes showed a lesser response. Na and Cl increased greatly and K decreased, indicating an inflammatory edema. Histamine concentration of inoculated glands decreased. The most dramatic change occurred in glycogen, which increased three- to fourfold in inoculated glands. This glycogen response appeared to be correlated with leukocytic invasion. Chemical changes induced by S. aureus were not marked as after E. coli infection.