383. Investigations on bovine mastitis.: 4. The association of new infections caused by Streptococcus agalactiae with (a) season and (b) stage of lactation

Abstract

Regular testing at 3-monthly intervals for periods extending to 7 years of some 650 to 850 cows in fourteen herds indicated that the majority of the new infections caused by Sir. agalactiae were recorded in the autumn months, August, September and October.When infections were considered in relation to the stage of lactation, although higher new infection values were recorded at the first test after calving than at later stages, the differences were not statistically significant.We are indebted to Dr D. N. Lawley for advice on the statistical interpretation of the results of this investigation.Acknowledgement is also made to the Agricultural Research Council for grants in aid of the investigation.