Swiss Dairy Farmers' Perceptions Surrounding the Disposal of Waste Milk Containing Antibiotic Residues and Antibiotic Resistance.

Véronique Bernier Gosselin,Mireille Meylan,Vivianne H M Visschers,Michèle Bodmer

doi:10.3389/fvets.2021.787828

Abstract

The feeding of waste milk containing antibiotic residues (WMA) to calves has been associated with the shedding of antibiotic-resistant bacteria by calves. However, little is known regarding farmers' intrinsic factors affecting this practice, and on which it would be relevant to intervene in order to change this practice. The objectives of this study were (1) to describe the farmers' intrinsic factors, such as perceived benefits, risks, and social norms related to the feeding of WMA to calves, antibiotic resistance, and antibiotic use, and (2) to evaluate how the feeding of WMA to calves is related to farmers' personal values and perceptions related to WMA feeding and antibiotic resistance. Answers to an online survey were collected from 233 Swiss dairy producers (38.3% response rate). The proportion of respondents who fed WMA to calves was 48.3%. In a hierarchical logistic regression model, only perception factors extracted by factor analysis were associated with the feeding of WMA to calves, namely (in decreasing order of magnitude): farm-level benefits of WMA feeding, the interaction of farm-level benefits with support from governmental authorities, and causes and threats of antibiotic resistance. The results suggest that, in order to reduce the feeding of WMA to calves, communications to dairy producers should focus on changing the perceived benefits of this practice in comparison to those of alternative WMA disposal methods carrying a lower risk of antibiotic resistance. The involvement of veterinarians and governmental authorities in these communications and in supporting producers may increase the successful adoption of alternative WMA disposal methods.

Highlights

Treatment of lactating dairy cows with most antibiotic drugs results in the production of waste milk containing antibiotic residues (WMA), which must be withheld from sale during the course of treatment and for a withdrawal period thereafter
Perceptions on Waste Milk Disposal come under scrutiny, as it has been associated with the selection of antibiotic resistance (AR) in the calves’ commensal microbial flora (8, 9)
The efficacy of WMA treatment or disposal methods in inactivating antibiotic residues has been reviewed (8, 11), but the implementation of these methods may be hindered by their limited on-farm applicability, high cost, or both

Summary

Introduction

Treatment of lactating dairy cows with most antibiotic drugs results in the production of waste milk containing antibiotic residues (WMA), which must be withheld from sale during the course of treatment and for a withdrawal period thereafter. On dairy farms in numerous countries, it is common practice to feed WMA to dairy calves (1–6). In a recent study in Switzerland, 47.3% of surveyed dairy producers used this WMA disposal method (7). This practice has Perceptions on Waste Milk Disposal come under scrutiny, as it has been associated with the selection of antibiotic resistance (AR) in the calves’ commensal microbial flora (8, 9). In Switzerland, the use of enzymes to inactivate antibiotic residues in milk is not permitted, and the disposal of WMA in biogas facilities requires important logistics from the producers, while only the feeding to calves allows to use the nutritional value of the milk (12). In order to decrease the impact of feeding WMA to calves on the development of AR on dairy farms, a better understanding of the factors affecting this practice is required

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Conclusion