Influence of Dairy Cows Bedding Material on the Microbial Structure and Antibiotic Resistance Genes of Milk.

Haoming Wu,Yang Wang,Huiying Li,Bingyao Du,Haiyan Hu,Nan Zheng,Lei Dong,Lu Meng,Jiaqi Wang

doi:10.3389/fmicb.2022.830333

Abstract

The presence of pathogenic bacteria and antibiotic resistance genes (ARGs) in milk are among the most important issues related to the safety of dairy products and the health of consumers. However, despite that dairy cow are housed for long periods of time on different beddings, the effect of different bedding materials on the microbiota and presence of ARGs is unclear. In this study, the composition of microorganisms, and the presence of mastitis pathogens and 33 ARGs targeting seven antibiotics in raw milk produced from farms using sand bedding, rice husk bedding, and recycled manure solids (RMS) bedding were compared by amplicon sequencing and real-time quantitative PCR. The results showed that the microbial composition of milk was related to the microbiota of bedding. None of the mastitis pathogens were detected in milk from cows housed on sand bedding (S-M). The proportion of ARGs was highest in the S-M group and lowest in the milk from cows housed on RMS bedding (RMS-M) group. In general, the content of ARGs in RMS-M was the lowest, however, the RMS bedding may pose a threat to the breast health of dairy cows.

Highlights

Milk is rich in nutrients, which supports human survival, but is a good culture medium for microorganisms (Akindolire et al, 2018; Regasa et al, 2019)
In the milk from cows housed on recycled manure solids (RMS) bedding, rice husks, and sand bedding, an average of 19,233, 51,110, and 52,553 reads were obtained, respectively
The results of this study revealed that no pathogenic bacteria were detected in the milk (S-M) produced from cows housed on sand bedding

Summary

Introduction

Milk is rich in nutrients, which supports human survival, but is a good culture medium for microorganisms (Akindolire et al, 2018; Regasa et al, 2019). In addition to pathogenic bacteria, there may be drug-resistant microorganisms in raw milk (MunschAlatossava and Alatossava, 2007; Caudell et al, 2018). Livestock feces can be used as an important potential source of pollution of pathogenic bacteria and antibiotic resistance genes (ARGs) in the environment. Sand and rice husk are often used as bedding materials for dairy cows. There is a small amount of microbiota in the sand bedding materials, and it has soft and comfortable performance, which can effectively maintain the breast health of dairy cows (Rowbotham and Ruegg, 2016b). Rice husk bedding and other organic materials are easier to make pathogenic bacteria survive and grow (Hogan and Smith, 2012). The effect of bacteria in bedding on the bacteria and ARGs in raw milk remains unclear

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