The occurrence of Campylobacter spp., Listeria monocytogenes and Shiga toxin-producing Escherichia coli in Norwegian dairy cattle farms; a comparison between free stall and tie stall housing systems.

Lene Idland,Erik G Granquist,Marina Aspholm,Toril Lindbäck

doi:10.31220/agrirxiv.2021.00091

Abstract

Abstract Aims: This study explores how different dairy farm operating systems influence the occurrence of zoonotic bacteria in raw milk. Methods and Results: Samples from bulk tank milk, milk filters, feces, feed, teats and teat milk were collected from eleven farms with loose housing and seven with tie-stall housing every second month over a period of 11 months and analyzed for the presence of Campylobacter spp., L. monocytogenes and STEC. Campylobacter spp., L. monocytogenes and STEC were abundant in samples from the farm environment and were also detected in 4%, 13% and 7% of the milk filters, respectively, and in 3%, 0% and 1% of bulk tank milk samples. Four STEC isolates carried the eae gene, which is linked to the capacity to cause more severe human disease. Conclusion: The results indicate a higher prevalence of L. monocytogenes and Campylobacter spp. in samples collected from loose housed herds compared to tie-stalled herds suggesting that the operating system can influence the food safety of raw milk. Significance and Impact of the study: This study highlights that zoonotic bacteria can be present in raw milk independent of hygienic conditions at the farm and what hosing system is used. Altogether, this study provides an important knowledge base for evaluating the risk of drinking unpasteurized milk.

Highlights

Pasteurization of cow milk has been a practice in Europe since the 1880’s to protect consumers from microbial pathogens (Steele 2000)
The results indicate a higher prevalence of L. monocytogenes and Campylobacter spp. in samples collected from loose housed herds compared to tie-stalled herds suggesting that the operating system can influence the food safety of raw milk
This study highlights that zoonotic bacteria can be present in raw milk independent of hygienic conditions at the farm and what hosing system is used

Summary

Introduction

Pasteurization of cow milk has been a practice in Europe since the 1880’s to protect consumers from microbial pathogens (Steele 2000). Serious human diseases such as tuberculosis, brucellosis and diphtheria have dramatically decreased with the introduction of industrial methods for thermal processing of milk (Lucey 2015). Since the beginning of the 21st century, consumption of UPM has grown in popularity in the Western world (Alegbeleye et al 2018). This trend is based on the belief that UPM tastes better, has probiotic effects and is more nutritious compared to its pasteurized counterpart (Claeys et al 2013; Crotta et al 2016). Some farmers and other actors in the agricultural community in Norway have requested relaxed rules for selling UPM (Jørgensen et al 2005)

Methods

Results

Discussion

Conclusion