280. The relationship of methods of bacteriological examination to the eradication and control of mastitis (Streptococcus agalactiae): I. The use of an enrichment technique in revealing streptococcal infections of the cow's udder: II.Streptococcus agalactiaeinfection in heifers

Abstract

In the course of attempts on a field scale to eradicate or controlStr. agalactiaeinfections, comparisons of the efficiency of several bacteriological methods have been made. It has been found that by using a method of enrichment, many cases of infection with small numbers ofStr. agalactiaecan be demonstrated in animals which give negative results by other methods. The frequency of examination has been shown to have an important influence upon the number of positive cases discovered.Light infections have been, proved to persist for long periods. Light infections withStr. dysgalactiaeandStr. uberishave also been found in many cases.Str. agalactiaehas been shown to be present in no less than 21 % of animals in their first lactation and 4·5 % of heifers were found to harbour this organism whilst in isolation before joining the herd. The bearing of these findings on the theory of contagion inStr. agalactiaeinfections has been discussed.