Infectious Bovine Mastitis

• Published in: Journal of dairy science Vol. 19; no. 10; pp. 641 - 650
• Main Authors: Plastridge, W.N., Anderson, E.O., Weirether, F.J., Johnson, R.E.
• Format: Journal Article
• Language: English
• Published: Elsevier Inc 01.10.1936
• ISSN: 0022-0302; 1525-3198
• DOI: 10.3168/jds.S0022-0302(36)93099-0

Observations on the incidence of streptococcal mastitis in seven experimental herds over periods of from one to six years are described. Data collected before and after the adoption of a program of segregation based on periodic examinations (chiefly bacteriological) and segregation of animals shedding streptococci identified as Streptococcus mastitidis (Group A)*are presented. The results obtained indicate that:1.The annual rate of spread of infectious streptococcal mastitis in infected herds may be reduced from 50 to 100 per cent by the use of the segregation plan described in this paper and in a previous publication (1).2.While the rate of spread of infection is materially reduced by segregating infected animals at one end of the milking string and milking them last, complete separation is necessary to entirely prevent the spread of infection.3.Herds free from Streptococcus mastitidis (Group A) may be established by segregation of the normal animals, disposal of infected individuals, and replacement by first calf heifers that have not been exposed to infection following parturition. The results presented support the opinion that it is possible to establish and maintain a herd free from the organism generally recognized as Streptococcus agalactiae. The writers are indebted to Professors L. F. Rettger and G. C. White for valuable suggestions in planning the work described herein.