An exploration study of CNS during the dry period in Dutch dairy cows.

Abstract

Coagulase-negative Staphylococcus (CNS) is a minor pathogen, but the prevalence is increasing in cows with a low somatic cell count (SCC) all over the world. And the overall SCC is lowering, because of well performed mastitis control programs. The bacterium is isolated from healthy and sick cows. In this study the risk and the presence of CNS was observed at the beginning and at the end of the dry period.

Part of a dry cow project (whereby farmers could voluntary participate) of the GD (Animal Health Service in the Netherlands), from 445 healthy cows throughout the Netherlands, with a low SCC, milk samples were collected before (D-sample) and after (K-sample) the dry period. From entering the dry period until 100 days in milk the cows were observed for the development of a clinical mastitis (CM).

In total 863 quarter samples were used for this study. With a CNS prevalence of 18,77%, there was no significant correlation between infection with CNS during the dry period and the development of a CM. With an relative risk (RR) smaller than 1, the risk of developing a CM for a quarter with CNS during the dry period was smaller than a quarter without it.

Because samples were taken before and after the dry period, it was also possible to look at the CNS infection development at quarter level during the dry period and the risk of developing a CM. In total 162 quarters were CNS positive, from which 21 were persistent, 50 fainted and 91 gained. So at the end of the dry period there were more quarters with CNS than at the start. But there was no significant correlation between CM and the CNS infection development.

Although the prevalence was high by cows with a low SCC, the risk of CM was low . Because CNS is not a homogeneous group, more strain specific research is needed for understanding and controlling CNS associated CM. This is important because of the risk of using antibiotic treatments without any sense especially regarding the problem of antibiotic resistance.