# Redefining on-farm practices: The perceived effect of a responsible antimicrobial use regulation on dairy farmers

Nikky Millar, Simon Dufour, Hélène Lardé, Jonathan Massé, Maud de Lagarde, Marie Archambault, John Morris Fairbrother, Jean-Philippe Roy, Catherine Belloc, David Francoz, et al.

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## To cite this version:

Nikky Millar, Simon Dufour, Hélène Lardé, Jonathan Massé, Maud de Lagarde, et al. Redefining on-farm practices: The perceived effect of a responsible antimicrobial use regulation on dairy farmers. Journal of Dairy Science, 2024, 107 (9), pp.6913-6929. 10.3168/jds.2024-24667. hal-05014527

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https://hal.inrae.fr/hal-05014527v1

Submitted on 31 Mar 2025

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# Redefining on-farm practices: The perceived effect of a responsible antimicrobial use regulation on dairy farmers

Nikky Millar,<fnref n="1" />,<fnref n="2" />,<fnref n="3" />,<fnref n="4" />* Simon Dufour,<fnref n="1" />,<fnref n="2" />,<fnref n="4" /> Hélène Lardé,<fnref n="7" /> Jonathan Massé,<fnref n="1" />,<fnref n="2" />,<fnref n="4" /> Maud De Lagarde,<fnref n="1" />,<fnref n="8" />,<fnref n="9" />
Marie Archambault,<fnref n="1" />,<fnref n="2" />,<fnref n="9" /> John Morris Fairbrother,<fnref n="1" />,<fnref n="8" />,<fnref n="9" /> Jean-Philippe Roy,<fnref n="4" />,<fnref n="5" /> Catherine Belloc,<fnref n="6" />
David Francoz,<fnref n="4" />,<fnref n="5" /> and Cécile Aenishaenslin<fnref n="1" />,<fnref n="2" />,<fnref n="3" />

## ABSTRACT

The global food animal industry faces a growing concern regarding antimicrobial resistance (AMR), primarily driven by the use of antimicrobials (AM) for the treatment, control, and prevention of diseases. Addressing this challenge requires promoting responsible antimicrobial use (AMU) practices. In 2019, the province of Québec, Canada, took a significant step by implementing a regulation that limits the use of AM of very high importance for human medicine (category I AM as defined by Health Canada) in the food animal industry. However, the implementation of such regulation can significantly influence behavioral shifts among producers, contributing to the wider effort against AMR. Therefore, the objective of this observational study was to describe the perceived changes in dairy producers' knowledge and on-farm practices following the implementation of this regulation, using a cohort design. Data collection involved administering questionnaires to 87 dairy producers from 3 regions of the province of Québec (Estrie, Montérégie, Centre-Du-Québec) before (2017–2018) and after (2020–2021) the implementation of the regulation. The questionnaires explored the descriptive characteristics of farms, the knowledge of producers about the categorization of AM, the on-farm treatment practices,

and the perceived effects of the regulation. Statistical analysis included *t*-tests and McNemar tests to compare the paired data obtained using the 2 questionnaires. The results indicated an increase in the knowledge score (the number of AM correctly categorized by the producers by their importance for human medicine) after the implementation of the regulation, suggesting an improved understanding of the categorization of AM based on their importance for human medicine. Trends in AMU practices for treating clinical mastitis and reproductive diseases suggested that category I AM were less likely to be reported as the primary treatment after the regulation, whereas category II AM were more often reported as primary treatment. Adoption of the selective dry cow therapy method significantly increased, whereas the use of teat sealants remained unchanged. Moreover, producers had divergent perceptions regarding the effect of the regulation on the cure rates and disease frequencies. This disparity emphasizes the need for comprehensive data collection to discern the risks associated with such regulatory shifts. The study acknowledges several limitations, including the potential for recall bias, confirmation bias, and desirability bias. Despite these limitations, this study shows that implementing regulations to encourage responsible AMU drives positive transformations in producers' knowledge and on-farm practices. This underscores the pivotal effect of proactive interventions in combating the escalating threat of AMR within the global food animal industry.

**Key words:** antimicrobial use, dairy, regulation, practices

Received January 11, 2024.

Accepted March 30, 2024.

*Corresponding author: nikky.millar@umontreal.ca

<footnote n="1">¹Department of Pathology and Microbiology, Faculty of Veterinary Medicine, Université de Montréal, Saint-Hyacinthe, J2S 2M2 QC, Canada</footnote>

<footnote n="2">²Groupe de recherche en épidémiologie des zoonoses et santé publique (GREZOSP), Faculty of Veterinary Medicine, Université de Montréal, Saint-Hyacinthe, J2S 2M2 QC, Canada</footnote>

<footnote n="3">³Centre de recherche en santé publique, Université de Montréal et Centre intégré de santé et de services sociaux du Québec du Centre-Sud-de-l'Île-de-Montréal, Montréal, H2L 4M1 QC, Canada</footnote>

<footnote n="4">⁴Regroupement FRQNT Op+lait, Saint-Hyacinthe, J2S 2M2 QC, Canada</footnote>

<footnote n="5">⁵Department of Clinical Sciences, Faculty of Veterinary Medicine, Université de Montréal, Saint-Hyacinthe, J2S 2M2 QC, Canada</footnote>

<footnote n="6">⁶Biologie, Épidémiologie et Analyses de risque en santé animale (BIOEPAR), ONIRIS-INRAE, 44300 Nantes, France</footnote>

<footnote n="7">⁷Department of Clinical Sciences, Ross University School of Veterinary Medicine, PO Box 334 Basseterre, St. Kitts, West Indies</footnote>

<footnote n="8">⁸WOOAH Reference Laboratory for *Escherichia coli*, Faculty of Veterinary Medicine, Université de Montréal, Saint-Hyacinthe, J2S 2M2 QC, Canada</footnote>

<footnote n="9">⁹Swine and Poultry Infectious Research Center (CRIPA-FQRNT), Faculty of Veterinary Medicine, Université de Montréal, Saint-Hyacinthe, J2S 2M2 QC, Canada</footnote>
INTRODUCTION

Antimicrobial resistance (AMR) poses a significant and worldwide concern within the food animal industry, given the frequent use of antimicrobials (AM) for the pre-vention, control (metaphylaxis use of AM), and treatment of bacterial infections (Aarestrup, 2015). Indeed, the use of these drugs can lead to the development of AMR in bacteria circulating in animals, which can then be trans-mitted to humans through direct contact, consumption of contaminated food, or environmental exposure (Tang et al., 2017). The emergence and dissemination of AMR can present significant challenges, leading to treatment de-lays, complexities, and potential threats to the well-being of both animal and human health (Dadgostar, 2019). It is thus essential to implement responsible antimicrobial use (AMU) practices. This includes reducing the inap-propriate use of AM by promoting disease prevention, enforcing guidelines and regulations, enhancing manage-ment practices, establishing monitoring and surveillance programs, and investing in research for the development of alternatives to AM, novel AM, and diagnostic tests. (Leung et al., 2011; Aenishaenslin et al., 2019; Gerber et al., 2021).

Over the last decades, the province of Québec has implemented several measures to address the emergence of AMR. Beginning in 1984, veterinary prescriptions for drugs such as AM and anti-inflammatories were made mandatory in the Canadian province of Québec (Roy et al., 2020). In 2015, a mandatory training course was pro-vided to veterinarians, emphasizing on the judicious use of AM (Roy et al., 2020). More recently, in 2019, a new regulation was introduced, marking another significant step in the province's efforts to combat AMR (Légis du Québec, 2019). This regulation limits the utilization of AM of very high importance for human medicine, catego-rized as category I AM by Health Canada (Government of Canada, 2017). This category of AM encompasses spe-cific AM such as third and fourth generation cephalospo-rins, polymyxin B, and fluoroquinolones. Category I AM hold pivotal roles in addressing severe infections where viable alternatives within human medicine are limited. This regulation mandates limiting the administration of category I AM in the food animal industry to therapeutic purposes and, to some extent, for metaphylaxis purposes within defined limits. Their use requires the prescription of a licensed veterinarian, contingent upon demonstrat-ing that alternative and less critical AM are unsuitable for treating the infection.

As one of the largest agri-food industries in Canada, with 9,739 dairy farms and approximatively 1.4 million lactating cows and heifers across the country in 2022, the implementation of this regulation on dairy farms could hold significant implications for the food animal industry

(Agriculture et Agroalimentaire Canada, 2021). Indeed, the province of Québec accounts for 36% of the revenue of the Canadian dairy industry, and estimates suggest that ~15% of the AM (defined course dose per 100 cows per year) used in Québec's dairy facilities were category I AM before the implementation of the regulation (Agriculture et Agroalimentaire Canada, 2021; Lardé et al., 2021). These latter AM were predominantly third generation cephalosporins administered by injection and designed for managing respiratory illnesses, or as intramammary formulations for addressing lactational and dry-off mas-titis treatments (Lardé et al., 2021). Other veterinary products labeled for use in cattle and containing category I AM (either polymyxins or fluoroquinolones) were also available in Canada during the period. However, the only product containing polymyxins was discontinued early in the study period (intramammary formulation for lac-tating cows), and an earlier study indicated that fluoro-quinolones were not used (Lardé et al., 2021). Research conducted 2 yr after the implementation of the regulation demonstrated a significant decrease in category I AMU across dairy farms in the province (Millar et al., 2022). Additionally, the prevalence of multidrug resistance in *Escherichia coli* isolates from fecal and manure pit samples in dairy farms decreased significantly from 83% to 71% (de Lagarde et al., 2022).

Nevertheless, changing AMU practices remain a complex and multifaceted process. It involves not only reducing AMU and AMR, but also acquiring new knowledge and improving preventive and biosecurity practices (Coyne et al., 2014; McKernan et al., 2021). Several studies have highlighted the concern of produc-ers regarding the potential consequences associated with the implementation of measures aimed at limiting the emergence of AMR, including effects on animal health, welfare, and economic viability (Golding et al., 2019; Millar et al., 2023). However, estimating the magnitude of these effects presents challenges, given the multitude factors that must be considered. These factors include production efficiency, AMU, the avail-ability of AM, resistance patterns among pathogens, the effectiveness of biosecurity measures, or regulatory compliance (Visschers et al., 2015; Tang et al., 2019a). This complexity often results in heterogeneous conclu-sions within the literature. A recent systematic review revealed that regulatory attempts to limit AMU may result in only marginal and temporary effects on animal health (McEwen et al., 2018). In contrast, studies have shown that reducing AMU has the potential to nega-tively affect animal health and well-being and, may po-tentially lead to economic repercussions, particularly if producers fail to adapt their preventive and biosecurity practices on their farms (Collineau et al., 2017; Lhermie et al., 2020).
Therefore, the main objective of this study was to describe changes in dairy producers' knowledge and their on-farm practices, mainly regarding the primary treatment they are considering for the most common diseases encountered on their farm, following the implementation of a regulation restricting the use of category I AM in the province of Québec, Canada. Moreover, we aimed to describe the perceived effects of the new regulation on dairy farms. We hypothesized that the following outcomes would be observed: (1) an increase in knowledge regarding the categorization of AM based on their relevance to human medicine, (2) a shift toward choosing category II AM as the primary treatment of mastitis and respiratory diseases, (3) an increased adoption of selective dry cow therapy and increased use of teat sealants, (4) an increased use of diagnostic tests and systemic signs for assessing the necessity of AM for the treatment of mastitis, (5) a perceived increase in the frequency of diseases, (6) no perceived change in the cure rates of diseases, (7) a negative perception of the regulation, and (8) a difficulty for producers to find alternative AM.

# MATERIALS AND METHODS

## Study Design

Using a cohort study design, questionnaires were administered to dairy producers before and after the implementation of the regulation. The collected data mainly encompassed the level of knowledge of dairy producers regarding AM, on-farm practices related to AMU and the perceived effects of the regulation on major diseases affecting both youngstock (referred to as nonweaned calves and weaned heifers throughout this article) and adult cows (referred to as lactating cows and dry cows throughout this article).

Ethical approval was obtained from the Comité d'éthique de la recherche en santé (CERES) of the Université de Montréal for data collection preregulation (16-163-CERES-D), and from the Comité d'éthique de la recherche en sciences et en santé (CERSES) of the Université de Montréal for data collection postregulation (CERSES-21-006-D).

## Recruitment

Dairy producers were recruited in 2017 through a stratified-random sampling method. The sampling was made from a list of 901 out of 2,187 producers selected randomly from 3 regions in the province of Québec, Canada (Estrie, Montérégie and Centre-du-Québec), which was provided by the Ministère de l'Agriculture, des Pêcheries et de l'Alimentation du Québec (MAPAQ). The recruited producers were originally asked to participate in an exten-

sive AMU and AMR monitoring study (Lardé et al., 2021; Massé et al., 2021; de Lagarde et al., 2022). Due to the data collection method, these regions were chosen based on their proximity to the Faculty of Veterinary Medicine of the Université de Montréal (Saint-Hyacinthe, QC, Canada) and their significance as prominent dairy areas in the province. The participation was on a voluntary basis. The total number of farms recruited was dictated by a sample size estimation described in Lardé et al. (2020) and was set to meet one of the original study objectives: achieving a power of 80% to describe AMU with a precision of ±50 defined daily doses/100 cow-years (Lardé et al., 2020). The number of recruited dairy producers in each region was determined to maintain a representative ratio in relation to the total number of farms in the province (19%, 10%, and 15% for Montérégie, Estrie, and Centre-du-Québec, respectively). Farms were excluded if: (1) replacement animals were not raised on the farm or if some of their animals were housed with cattle from another farm, (2) cessation of activity was planned in the coming 12 mo, or (3) the farm was already used in a pilot stage for the current project. For further insights into the recruitment process, details can be found in Lardé et al. (2021). Producers who participated in the first questionnaire were re-contacted by phone in 2020, ~15 mo after the implementation of the new regulation, to request their participation to a second questionnaire. They had the option to withdraw their participation.

## Data Collection

Data collection involved the use of 2 questionnaires developed by the research team and administered from 2017 to 2018, referred to as the preregulation questionnaire, and from 2020 to 2021, referred to as the postregulation questionnaire. The questionnaires were designed to collect data on various themes, with most questions being the same in the pre- and postregulation questionnaires.

**Descriptive Characteristics of Farms.** The first theme focused on descriptive characteristics of the farms, encompassing open questions about quotas, income related to lactating cows, the number of animals in different age groups (nonweaned calves, weaned heifers, lactating cows, dry cows), the number of veterinary visits for preventive and curative purposes, and the number of animals by breed and number of animals purchased per year. It also included a closed question about organic certification (yes or no).

**Knowledge.** The second theme aimed to assess participants' knowledge about AM through closed questions regarding the categorization of commonly used AM in dairies, categorized according to their importance for human medicine (response options: AM of very high
importance for human medicine, not an AM of very high importance for human medicine, do not know its importance for human medicine, do not know this product). Eight groups of AM were included: (1) intramammary third generation cephalosporins (category I AM); (2) injectable third generation cephalosporins (category I AM); (3) first generation cephalosporins (category II AM); (4) macrolides (category II AM); (5) trimethoprim-sulfonamide combinations (category II AM); (6) penicillin (category II AM); (7) tetracyclines (category III AM); and (8) ionophores (category IV AM). This theme also included a question about previous training on the judicious use of AM (yes/no).

**On-farm Practices.** The third theme aimed to describe on-farm practices related to AMU. It included open questions about their first chosen option for treating common diseases in youngstock (including diarrhea, respiratory diseases, otitis and septic arthritis) and adult cows (including reproductive diseases, clinical mastitis, respiratory diseases, and footrot). Additionally, it included questions about dry cow therapy methods use (blanket, selective or none), the use of teat sealants at dry-off (systematically, occasionally, never) and the use of AM in youngstock's feed or milk (yes or no). Finally, it also included open-ended questions concerning the decision criteria for initiating treatment of common diseases in youngstock (including diarrhea, respiratory diseases, otitis, and septic arthritis) and adult cows (including reproductive diseases, clinical mastitis, respiratory diseases, and footrot). Questions about decision criteria were only asked in the postregulation questionnaire, and producers were required to answer only if they had modified their decision criteria between the pre- and postregulation questionnaires.

**Perceived Effects.** The fourth theme aimed to describe the perceived effects resulting from the implementation of the regulation. It included questions about the perceived change in the cure rate (major improvement, minor improvement, same, minor worsening, major worsening, do not know) and in the frequency of disease (increase a lot, increase a little, same, decrease a little, decrease a lot, do not know) after the implementation of the regulation, and for diseases of nonweaned calves (including diarrhea, respiratory diseases, otitis, septic arthritis, and omphalitis), weaned heifers (including diarrhea, respiratory diseases, otitis, septic arthritis, and omphalitis), as well as for adult cows (including reproductive diseases, diarrhea, clinical mastitis, respiratory diseases, and footrot). It also included questions about the producers' satisfaction with the new regulation (totally agree, agree, disagree, totally disagree). Questions evaluating the perceived effects' theme were only included in the postregulation questionnaire.

**Availability of AM.** The fifth and last theme aimed to describe the problems with the availability of AM (never, rarely, occasionally, often). This latter question was added because between June 2019 and May 2020, many AM (e.g., for clinical mastitis and dry cow therapy, injectable ampicillin, and all injectable tetracyclines) were reported as not available or discontinued (Millar et al., 2023).

The full questionnaires can be found in Supplemental File S1 (preregulation questionnaire, see Notes) and Supplemental File S2 (postregulation questionnaire, see Notes). Both were in French and were reviewed by collaborators and tested with a group of 10 dairy producers (preregulation questionnaire) and 5 dairy producers (postregulation questionnaire). Feedback on question clarity, order and flow, skip patterns, and timing was carefully considered in the process of refining the questionnaires. Adjustments were made to the postregulation and were influenced by insights gathered from consultations with the research team responsible for the preregulation questionnaire. Questionnaires were administered to producers in person by one member of the research team (HL and JM for the preregulation questionnaire, and MDL for the postregulation questionnaire).

## Data Analyses

Raw data collected with the pre- and postregulation questionnaires were transformed to enable comparison between the 2 questionnaires.

**Knowledge about AM.** To evaluate and compare the level of knowledge of producers about AM, a global knowledge score, ranging from 0 to 8, was calculated by summing the scores (0 = incorrect, 1 = correct answer) obtained from the categorization of 8 groups of AM, for each study period. If a producer responded "do not know the importance of this AM for human medicine" or "do not know this AM" for a group of AM, it was considered as an incorrect answer.

**On-Farm Practices.** To describe the change in the first chosen option for treating common diseases, producers were required to name all AM they used to treat a disease for both youngstock and adult cows in the preregulation questionnaire whereas in the postregulation questionnaire, they had to name the most frequently used AM. For initial analysis, when a producer gave more than one answer in the preregulation questionnaire, only the most critical AM (higher category in Health Canada categorization) was kept for analysis. Subsequently, a sensitivity analysis was conducted to evaluate the effect of that latter decision. For this sensitivity analysis, whenever a producer reported 2 different potential treatments for a disease (e.g., a category I AM and a category II AM), it was then categorized as using a combination of category
I AM and category II AM (vs. being labeled as using a category I in the first analysis).

Regarding the use of teat sealants at dry-off, producers who responded that they systematically or occasionally used teat sealants were grouped together in a category “use sealants at dry-off.”

To compare decision criteria for initiating treatments of common diseases of youngstock and adult cows, criteria reported by producers were divided into 5 groups: (1) treatment of all cases, (2) presence of systemic signs (anorexia, lethargic, and fever grouped together as responses), (3) according to results from diagnostic tests (on-farm testing such as the California mastitis test or laboratory testing [e.g., antibiotic susceptibility testing] culture), (4) according to veterinarian's recommendation, and (5) other factors (such as disease duration and additional clinical signs such as inflammation, cough, lameness, or presence of clots in the milk). Producers could be included in more than one group when they mentioned relying on multiple criteria for treatment decision. These groupings were determined by consensus within the research group, aligning with the research objectives.

**Perceived Effects.** To describe the perceived changes in the cure rate and in the frequency of diseases, producers' responses were dichotomized. Responses categorized as “minor worsening” and “major worsening” for the cure rate were merged into a single category referred to as “worsen.” Similarly, responses categorized as “minor improvement” and “major improvement” were combined into a single category referred to as “improve.” Producers who responded “do not know” were excluded from the analysis.

## Statistical Analyses

For continuous variables, descriptive statistics including means and lower and upper quartiles were used to summarize the data. Paired or simple *t*-tests were used to determine if differences between post- and preregulation were significant. For ordinal and nominal variables, the proportion of producers in each category was visualized using stacked bar charts. A CI for the population proportion was estimated when possible (perceived effects of the regulation). For nominal variables, a McNemar test (organic certification, previous training about judicious use of AM, use of teat sealants at dry-off, use of AM in feed and milk) or McNemar-Bowker test (the first chosen option for treating common diseases, dry cow therapy methods, decision criteria for initiating treatment) was performed. For variables with more than 2 categories (decision criteria for initiating treatment), a pairwise McNemar test was performed with a Bonferroni adjustment for multiple comparisons if the McNemar-Bowker

test yielded a *P*-value <0.05. To respect the test assumptions, if fewer than 10 discordant pairs were included in the pairwise comparison, the test was not performed. Regarding decision criteria for initiating treatment, producers who reported using more than one group of criteria were excluded from the analysis to respect assumptions of the McNemar-Bowker test.

A second and similar statistical approach was used for inquiries concerning “first chosen option for treating common diseases” and “decision criteria to initiate an AM treatment.” However, certain changes were made about categorization of responses. This approach entailed segregating responses into 2 groups: one representing utilization of a specific decision criterion or category I AM, and the other signifying the absence of criterion usage or nonutilization of a category I AM. For instance, this distinction could involve comparing the application of a decision criterion such as systemic signs versus its nonapplication, or the use of a category I AM versus its nonuse. McNemar tests were subsequently conducted for each criterion or AM category, facilitating a comparison of outcomes between these 2 groups. All statistical analyses were performed using SAS version 9.4 (SAS Institute Inc., Cary, NC). A significance level of (*P* < 0.05) was used to determine statistical significance.

## RESULTS

### Descriptive Characteristics of Farms

Out of the initial pool of 901 producers provided by the MAPAQ, 238 were reached by phone, and a total of 102 (43%) agreed to participate to the preregulation questionnaire. Among these, 44 were from the Montérégie region, 35 were from the Centre-du-Québec region, and 22 were from the Estrie region. The number of farms per region was fixed to represent the actual region to province ratio. The numbers of lactating cows, owned quota, and amount of milk produced by cow-day were obtained from both the 102 participating producers and the 136 producers who declined to participate. These values were statistically compared and were not significantly different between participating and nonparticipating producers, thus excluding the possibility of a selection bias (see Lardé et al., 2020 for details). Subsequently, of these 102 producers, 1 producer quit the original study early on, and 87 consented to participate to the postregulation questionnaire: 41 producers from the Montérégie region, 29 from the Centre-Du-Québec region, and 17 from the Estrie region. Out of the 14 producers who did not take part in the postregulation questionnaire, 5 had ceased dairy farming, 1 had retired, and 4 declined to participate (reasons included lack of time [n = 1] and lack of interest [n = 3]). Additionally, 4 producers did not participate for
unknown reasons. Consequently, we excluded these 14 producers from further analysis.

Table 1 provides an overview of the characteristics of the recruited farms during the 2 study periods. The study included only one organic farm (1.4%). The average daily dairy quota was 71.8 kg in the preregulation questionnaire and 74.6 kg in the postregulation questionnaire, representing an increase of 2.8 kg (95% CI: 1.6–3.9; Table 1). The average number of lactating cows per farm increased by 2.2 cows (95% CI: 0.4–4.0), from 59.5 to 61.6. The average number of curative veterinary visits per year decreased by 1.9 visits/yr (95% CI: –3.8–0.1) between the 2 periods.

## Knowledge

Seven producers did not complete the corresponding question in the postregulation questionnaire as they indicated before answering the question that they were not familiar with the categorization, resulting in their exclusion from this specific analysis. However, it is worth noting that they did try to respond to the same question in the preregulation questionnaire. The mean number of mistakes decreased from 6.7 mistakes to 0.7 mistakes between the 2 periods with a mean reduction of 5.9 mistakes (95% CI: –6.4 to 5.5; Table 1). The percentage of dairy producers who followed an optional training course about judicious usage of AM increased significantly from 2% (n = 2) to 41% (n = 36) of producers (n = 87; *P* < 0.001) between the 2 periods. Additionally, when estimating the knowledge score difference between pre- and postregulation questionnaires, it was noted that producers who did not attend the training course exhibited a mean difference of –5.9 mistakes (n = 47), whereas those who participated in the training course showed a similar mean difference of –6.1 mistakes (n = 33).

## On-farm Practices

Table 2 presents the significative results of various statistical approaches (McNemar-Bowker test, pairwise McNemar test, and McNemar test comparing the use of category I AM to nonuse of category I AM) used to describe the changes in the first chosen option for treating common diseases. For the treatment of respiratory diseases of youngstock, the proportion of producers choosing a category III AM as a primary treatment, significantly (*P* = 0.049) decrease from 34.5% (30/87) to 23.0% (20/87), and the proportion of producers who reported not using any AM treatment increased significantly (*P* = 0.049) from 19.5% (17/87) to 35.6% (31/87) in the post-regulation questionnaire. The proportion of producers choosing a category I AM as primary treatment of reproductive diseases in adult cows significantly (*P* < 0.001)

decreased from 33.3% (29/87) to 1.3% (1/87). The proportion of producers choosing a category I AM for treating clinical mastitis significantly (*P* < 0.001) decreased from 81.6% (71/87) to 4.6% (4/87), whereas the choice of a category II AM significantly (*P* < 0.001) increased from 4.6% (4/87) to 79.3% (69/87). Producers who chose a category I AM as main treatment of respiratory diseases of adult cows significantly (*P* < 0.001) decreased from 26.4% (23/87) to 0% (0/87). We did not conduct any statistical analysis for otitis (number of respondents = 10 producers), septic arthritis (number of respondents = 20 producers), and footrot (number of respondents = 32 producers). We observed the same trend as described in the sensitivity analysis when considering all treatments reported for a given disease by a producer (data not shown). In brief, we observed a significant decrease (*P* < 0.001) in proportion of producers choosing a category I AM as primary treatment for reproductive diseases, from 19.5% (15/77) to 1.3% (1/77). Additionally, producers who chose a category I AM for clinical mastitis treatment significantly (*P* < 0.001) decreased from 80.9% (68/84) to 11.9% (10/84), whereas the choice of a category II AM significantly (*P* < 0.001) increased from 47.6% (40/84) to 77.4% (65/84). The proportion of producers choosing a category I AM as primary treatment of respiratory diseases in adult cows also decreased significantly (*P* < 0.001), from 11.9% (10/84) to 0.0% (0/84). However, we did not observe a significant decrease in the treatment of major diseases in youngstock.

The proportion of producers choosing blanket dry cow therapy significantly (*P* < 0.001) decreased from 77.0% (67/87) to 57.1% (48/84), whereas those opting for selective dry cow therapy increased significantly (*P* < 0.001) from 22.9% (20/87) to 42.9% (36/84) in the postregulation questionnaire. Three producers did not answer the question in the postregulation questionnaire. The proportion of producers choosing to use teat sealants showed no significant (*P* = 0.405) change (preregulation questionnaire: 39.1% [34/87]); postregulation questionnaire 35.6% (31/87). The use of medicated ingredients in feed decreased significantly (*P* < 0.001) from 47.1% (41/87) to 6.9% (6/87) among producers. Anticoccidal agents remained the most common medicinal ingredient used by producers in both periods (65.9% [27/41] pre-regulation questionnaire and 50.0% [3/6] postregulation questionnaire). Tetracycline (Health Canada categorization: category III) was used by 34.1% (14/41) of the producers and 50% (3/6) of the producers, respectively. In both questionnaires, 43.7% (38/87) of dairy producers fed milk from sick cows to their calves, and 2.6% (2/87) of producers fed their calves with milk from cows recently treated with AM.

Figure 1 (youngstock) and Figure 2 (adult cows) illustrate the changes in decision criteria for initiating
<table><caption>**Table 1.** Sociodemographic characteristics, knowledge, and use of AM of 87 dairy farms from 3 regions of the province of Québec (Estrie, Montérégie, Centre-Du-Québec) before (2017/2018) and after (2020/2021) the implementation of a regulation restricting the use of antimicrobials of very high importance for human medicine in the province of Québec, Canada</caption><thead><tr><th rowspan="2">Item</th><th colspan="3">2017/2018</th><th colspan="3">2020/2021</th><th colspan="3">Simple t-test on the difference<sup>3</sup></th><th colspan="3">IC95%</th></tr><tr><th>Mean</th><th>Q1<sup>1</sup></th><th>Q3<sup>2</sup></th><th>Mean</th><th>Q1<sup>1</sup></th><th>Q3<sup>2</sup></th><th>t-value</th><th>df</th><th>P-value</th><th>Mean difference</th><th>Lower</th><th>Upper</th></tr></thead><tbody><tr><td>Quotas (kg of fat/d)</td><td>71.8</td><td>50.0</td><td>86.0</td><td>74.6</td><td>52.0</td><td>92.0</td><td>4.0</td><td>86</td><td>&lt;0.0001</td><td>2.8</td><td>1.6</td><td>3.9</td></tr><tr><td>Annual income (×1,000 $CAN)</td><td>85.9</td><td>80.0</td><td>98.0</td><td>86.4</td><td>80.0</td><td>100.0</td><td>0.4</td><td>86</td><td>0.70</td><td>0.4</td><td>-1.8</td><td>2.8</td></tr><tr><td>Cows by breed (%)</td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td></tr><tr><td>Holstein</td><td>94.6</td><td>97.0</td><td>100.0</td><td>90.6</td><td>98.0</td><td>100.0</td><td>0.5</td><td>86</td><td>0.65</td><td>0.2</td><td>-0.8</td><td>1.4</td></tr><tr><td>Jersey</td><td>4.0</td><td>0.0</td><td>0.0</td><td>4.3</td><td>0.0</td><td>1.0</td><td>0.9</td><td>86</td><td>0.36</td><td>0.3</td><td>-0.3</td><td>0.9</td></tr><tr><td>Other</td><td>2.7</td><td>0.0</td><td>0.0</td><td>1.9</td><td>0.0</td><td>0.0</td><td>-1.5</td><td>86</td><td>0.13</td><td>-0.7</td><td>-1.6</td><td>0.2</td></tr><tr><td>Cows by age (n)</td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td></tr><tr><td>Youngstock</td><td>25.5</td><td>15.8</td><td>31.5</td><td>25.0</td><td>16.3</td><td>31.8</td><td>0.29</td><td>86</td><td>0.77</td><td>0.2</td><td>-5.0</td><td>5.5</td></tr><tr><td>Lactating cows</td><td>59.5</td><td>42.0</td><td>71.0</td><td>61.6</td><td>44.0</td><td>75.0</td><td>2.4</td><td>86</td><td>0.02</td><td>2.2</td><td>0.4</td><td>4.0</td></tr><tr><td>Dry cows</td><td>8.4</td><td>5.0</td><td>10.0</td><td>8.4</td><td>5.0</td><td>10.0</td><td>.</td><td>86</td><td>.</td><td>0</td><td>0</td><td>0</td></tr><tr><td>Veterinary visits/yr (n)</td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td></tr><tr><td>Curative</td><td>12.0</td><td>6.0</td><td>13.0</td><td>10.0</td><td>5.0</td><td>12.0</td><td>-2.1</td><td>86</td><td>0.04</td><td>-1.9</td><td>-3.75</td><td>-0.09</td></tr><tr><td>Preventive</td><td>16.0</td><td>12.0</td><td>24.0</td><td>16.0</td><td>12.0</td><td>24.0</td><td>0.6</td><td>86</td><td>0.53</td><td>0.4</td><td>-0.88</td><td>1.72</td></tr><tr><td>Animals purchased/yr (n)</td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td></tr><tr><td>Youngstock</td><td>0.1</td><td>0.0</td><td>0.0</td><td>0.3</td><td>0.0</td><td>0.0</td><td>-1.5</td><td>86</td><td>0.14</td><td>-0.7</td><td>0.0</td><td>0.0</td></tr><tr><td>Adult cows</td><td>4.0</td><td>2.0</td><td>6.0</td><td>2.0</td><td>0.0</td><td>1.0</td><td>-0.6</td><td>86</td><td>0.53</td><td>-0.9</td><td>-1.7</td><td>3.3</td></tr><tr><td>Animals transported/yr (n)</td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td></tr><tr><td>Youngstock</td><td>1.1</td><td>0.0</td><td>4.0</td><td>0.8</td><td>0.0</td><td>0.0</td><td>-0.74</td><td>86</td><td>0.45</td><td>-0.3</td><td>0.0</td><td>0.0</td></tr><tr><td>Adult cows</td><td>1.3</td><td>0.0</td><td>1.0</td><td>0.2</td><td>0.0</td><td>0.0</td><td>-2.0</td><td>86</td><td>0.05</td><td>-1.5</td><td>-1.0</td><td>0.0</td></tr><tr><td>Knowledge about AM<sup>4</sup></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td></tr><tr><td>Mistakes (number of mistakes/8)</td><td>6.7</td><td>6</td><td>8</td><td>0.7</td><td>0</td><td>1</td><td>-25.1</td><td>79</td><td>&lt;0.0001</td><td>-5.9</td><td>-6.4</td><td>-5.5</td></tr><tr><td>Number of treatments of category I AM by farm<sup>5</sup>/100 animals-year</td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td></tr><tr><td>Youngstock</td><td>2.2</td><td>0</td><td>0</td><td>0.2</td><td>0</td><td>0</td><td>-1.59</td><td>86</td><td>0.1161</td><td>-1.1</td><td>-2.5</td><td>0.3</td></tr><tr><td>Lactating cows</td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td></tr><tr><td>Injectable AM (n)</td><td>13.8</td><td>5.7</td><td>16.1</td><td>1.1</td><td>0</td><td>0</td><td>-5.67</td><td>86</td><td>&lt;0.0001</td><td>-8.1</td><td>-10.5</td><td>-5.3</td></tr><tr><td>Intramammary AM (n)</td><td>4.5</td><td>0</td><td>6.5</td><td>3.1</td><td>0</td><td>5.0</td><td>-1.60</td><td>86</td><td>0.1127</td><td>-1.3</td><td>-2.8</td><td>0.3</td></tr><tr><td>Dry cows</td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td></tr><tr><td>Injectables AM (n)</td><td>1.1</td><td>0</td><td>0</td><td>0.5</td><td>0</td><td>0</td><td>-0.86</td><td>86</td><td>0.3919</td><td>-0.6</td><td>-2.1</td><td>0.8</td></tr><tr><td>Intramammary AM (n)</td><td>7.1</td><td>0</td><td>0</td><td>0</td><td>0</td><td>0</td><td>-3.21</td><td>86</td><td>0.0019</td><td>-7.1</td><td>-11.6</td><td>-2.7</td></tr></tbody></table>

¹Q1 = first quartile, meaning that 25% of the data falls below the first quartile.

²Q3 = third quartile, meaning that 75% of the data falls below the third quartile.

³t-value = a ratio of the difference between the mean of the 2 sample sets and the variation that exists within the sample sets; IC95% = CI.

⁴Corresponds to any misclassification between very high importance antimicrobials and other categories of antimicrobials. The groups of antimicrobials to be categorized in the questionnaire by their importance for human medicine (Canada Health) were: Category 1 antimicrobials: third generation cephalosporins (injectables), third generation cephalosporin (intramammary); Other categories: trimethoprim-sulfamethoxazole, first generation cephalosporins, macrolides, ionophores, tetracyclines, penicillin.

⁵Category 1 AM = third generation cephalosporin, fluoroquinolones, and polymyxin B.
<table><caption>**Table 2.** Changes in the primary treatment chosen by 87 dairy producers, without a veterinarian exam, for the treatment of common diseases of youngstock (diarrhea and respiratory diseases) and adult cows (reproductive diseases, clinical mastitis, and respiratory diseases) before (2017/2018) and after (2020/2021) the implementation of a regulation restricting the use of antimicrobials of very high importance for human medicine in the province of Québec, Canada†</caption><thead><tr><th rowspan="3">Item</th><th rowspan="3">Category</th><th colspan="7">2020/2021</th></tr><tr><th colspan="6">Other treatment than</th><th rowspan="2">Total (%)</th></tr><tr><th>Category 1 AM (%)</th><th>Category 2 AM (%)</th><th>Category 3 AM (%)</th><th>AM (%)</th><th>No treatment (%)</th></tr></thead><tbody><tr><td rowspan="7">2017/2018 Youngstock</td><td>Diarrhea*†</td><td></td><td></td><td></td><td></td><td></td><td></td></tr><tr><td>Category 1 AM (%)</td><td>0</td><td>1</td><td>0</td><td>2</td><td>3</td><td>7</td></tr><tr><td>Category 2 AM (%)</td><td>0</td><td>15</td><td>3</td><td>6</td><td>5</td><td>29</td></tr><tr><td>Category 3 AM (%)</td><td>0</td><td>0</td><td>0</td><td>0</td><td>1</td><td>1</td></tr><tr><td>Other treatments than AM (%)</td><td>0</td><td>6</td><td>8</td><td>10</td><td>7</td><td>31</td></tr><tr><td>No treatment (%)</td><td>0</td><td>6</td><td>2</td><td>2</td><td>22</td><td>32</td></tr><tr><td>Total (%)</td><td>0</td><td>27</td><td>14</td><td>21</td><td>38</td><td>100</td></tr><tr><td rowspan="7">Adult cows</td><td>Respiratory diseases*</td><td></td><td></td><td></td><td></td><td></td><td></td></tr><tr><td>Category 1 AM (%)</td><td>0</td><td>0</td><td>0</td><td>0</td><td>1</td><td>1</td></tr><tr><td>Category 2 AM (%)</td><td>0</td><td>28</td><td>8</td><td>0</td><td>9</td><td>45</td></tr><tr><td>Category 3 AM (%)</td><td>0</td><td>8</td><td>14</td><td>0</td><td>13</td><td>35</td></tr><tr><td>Other treatments than AM (%)</td><td>0</td><td>0</td><td>0</td><td>0</td><td>0</td><td>0</td></tr><tr><td>No treatment (%)</td><td>0</td><td>6</td><td>1</td><td>0</td><td>13</td><td>19</td></tr><tr><td>Total (%)</td><td>0</td><td>42</td><td>23</td><td>0</td><td>36</td><td>100</td></tr><tr><td rowspan="7">Adult cows</td><td>Reproductive diseases*†</td><td></td><td></td><td></td><td></td><td></td><td></td></tr><tr><td>Category 1 AM (%)</td><td>0</td><td>29</td><td>0</td><td>2</td><td>2</td><td>33</td></tr><tr><td>Category 2 AM (%)</td><td>1</td><td>35</td><td>0</td><td>1</td><td>1</td><td>38</td></tr><tr><td>Category 3 AM (%)</td><td>0</td><td>0</td><td>0</td><td>0</td><td>0</td><td>0</td></tr><tr><td>Other treatments than AM (%)</td><td>0</td><td>5</td><td>0</td><td>0</td><td>2</td><td>7</td></tr><tr><td>No treatment (%)</td><td>0</td><td>17</td><td>0</td><td>1</td><td>3</td><td>22</td></tr><tr><td>Total (%)</td><td>1</td><td>85</td><td>0</td><td>5</td><td>9</td><td>100</td></tr><tr><td rowspan="7">Adult cows</td><td>Clinical mastitis*</td><td></td><td></td><td></td><td></td><td></td><td></td></tr><tr><td>Category 1 AM (%)</td><td>5</td><td>68</td><td>0</td><td>0</td><td>9</td><td>82</td></tr><tr><td>Category 2 AM (%)</td><td>0</td><td>5</td><td>0</td><td>0</td><td>0</td><td>5</td></tr><tr><td>Category 3 AM (%)</td><td>0</td><td>0</td><td>0</td><td>0</td><td>0</td><td>0</td></tr><tr><td>Other treatment than AM (%)</td><td>0</td><td>0</td><td>0</td><td>0</td><td>0</td><td>0</td></tr><tr><td>No treatment (%)</td><td>0</td><td>7</td><td>0</td><td>0</td><td>7</td><td>14</td></tr><tr><td>Total (%)</td><td>5</td><td>79</td><td>0</td><td>0</td><td>16</td><td>100</td></tr><tr><td rowspan="7">Adult cows</td><td>Reproductive diseases†</td><td></td><td></td><td></td><td></td><td></td><td></td></tr><tr><td>Category 1 AM (%)</td><td>0</td><td>14</td><td>0</td><td>0</td><td>13</td><td>26</td></tr><tr><td>Category 2 AM (%)</td><td>0</td><td>6</td><td>0</td><td>0</td><td>3</td><td>9</td></tr><tr><td>Category 3 AM (%)</td><td>0</td><td>0</td><td>0</td><td>0</td><td>0</td><td>0</td></tr><tr><td>Other treatment than AM (%)</td><td>0</td><td>0</td><td>0</td><td>0</td><td>0</td><td>0</td></tr><tr><td>No treatment (%)</td><td>0</td><td>22</td><td>2</td><td>0</td><td>40</td><td>64</td></tr><tr><td>Total (%)</td><td>0</td><td>41</td><td>2</td><td>0</td><td>56</td><td>100</td></tr></tbody></table>

treatments of common diseases. The proportion of producers opting to treat all cases of reproductive diseases and clinical mastitis significantly (*P* < 0.001) decreased between the 2 questionnaires, from 29.8% (25/84) to 10.7% (9/84) and from 34.5% (29/84) to 11.9% (10/84), respectively. For initiating treatment of reproductive diseases, we observed a significant (*P* = 0.049) increase in using systemic signs, from 53.6% (45/84) to 65.5% (55/84). Specifically, the use of fever as a decision criterion increased significantly (*P* = 0.011) from 47.1% (40/84) to 62.0% (52/84), and anorexia or lethargy increased significantly (*P* < 0.001) from 19.0% (16/84) to 24.0% (20/84). Other signs such as disease duration and foul odor of metritis or retained placenta were also considered. Regarding clinical mastitis treatment, the use

of diagnostic tests significantly (*P* < 0.001) increased from 7.1% (6/84) to 28.6% (24/84) as a decision criterion. Producers also considered systemic signs such as fever, anorexia, lethargy, and other disease indicators such as disease duration, udder inflammation, and clots in milk during both periods, with no significant changes observed. We observed no significant changes between the 2 questionnaires in the use of decision criteria for initiating treatment for other diseases in youngstock and adult cows.

Perceived Effects

Figure 3 presents the perceptions of 87 dairy producers regarding the cure rates of various diseases. Among them,

<footnote>*McNemar-Bowker test *P* < 0.05; †*P* < 0.05 for the McNemar test comparing the use of category 1 versus the nonuse of category 1 AM; bold data: *P* < 0.05 for the McNemar test comparing the use of the 2 categories of AM.</footnote>
A

<figure><img src="image_4.png" /></figure>

B

<figure><img src="image_5.png" /></figure>

C

<figure><img src="image_6.png" /></figure>

D

<figure><img src="image_7.png" /></figure>

**Figure 1.** Decision criteria used for initiating antimicrobial treatment for (A) diarrhea; (B) respiratory diseases; (C) otitis; and (D) septic arthritis of youngstock in dairy farms before (2017–2018) and after (2020–2021) the implementation of a regulation restricting the use of antimicrobials of very high importance in animal production in the province of Québec, Canada. No significant changes (*P*-value <0.05) were observed between the pre- and postregulation questionnaires.

10.5% (9/85; IC95%:7.2–14.0) perceived an overall improvement of the cure rates of diseases, whereas 22.4% (19/85; IC95%: 17.7–27.0) felt that the overall cure rate had worsened. Specifically, for nonweaned calves, 14.0% (10/73; IC95%: 9.6–17.9), 11.6% (7/60; IC95%: 7.4–15.9), and 10.0% (3/30; IC95%: 4.4–15.6) noticed improvements in the cure rates of diarrhea, respiratory diseases, and septic arthritis, respectively. Meanwhile, 15.1% (11/73; IC95%: 10.8–19.3), 18.3% (11/60; IC95%: 13.2–23.4), and 30.0% (9/30; IC95%: 21.4–38.6) perceived a worsening in these cure rates. Concerning respiratory diseases of weaned heifers, 9.4% (3/32; IC95%: 4.1–14.7) perceived an improvement of the cure rate, compared with 18.8% (6/32; IC95%: 11.7–25.9) who perceived that the cure rate had worsened. Concerning reproductive diseases in adult cows, 7.2% (6/83; IC95%: 4.3–10.1) reported an improvement, whereas 10.8% (9/83; IC95%: 7.3–14.3)

believed that the cure rate had worsened. Moreover, 9.3% (8/86; IC95%: 6.1–12.5) of producers noted an improvement in the cure rate of clinical mastitis, compared with 44.2% (38/86; IC95%: 38.7–49.7) who perceived that the cure rate had worsened. Regarding footrot, 26.2% (11/42; IC95%: 19.2–33.1) of producers saw an improvement, with none reporting a worsening. Regarding respiratory diseases of adult cows, 9.3% (4/43; IC95%: 4.7–13.8) of producers noted an improvement of the cure rate, whereas 14.0% (6/43; IC95%:8.5–19.4) of producers perceived that the cure rate had worsened. For other diseases affecting nonweaned calves, weaned heifers, and adult cows, less than 30 producers responded to the question or less than 10% of producers noticed improvements or worsening in the cure rates.

Figure 4 presents the producers' perceptions regarding the frequency of various diseases. Out of the 87 produc-
<figure><img src="image_8.png" /><figcaption>B</figcaption></figure>

<figure><img src="image_9.png" /><figcaption>C</figcaption></figure>

<figure><img src="image_10.png" /><figcaption>D</figcaption></figure>

<figure><img src="image_11.png" /></figure>

**Figure 2.** Decision criteria used for initiating antimicrobials treatment for (A) reproductive diseases (B) clinical mastitis; (C) respiratory diseases; and (D) footrot of adult cows in dairy farms before (2017–2018) and after (2020–2021) the implementation of a regulation restricting the use of antimicrobials of very high importance in animal production in the province of Québec, Canada. \*A significant change (P-value < 0.05) between the pre- and postregulation questionnaires.

ers, 77.9% (67/86; IC95%: 73.3–82.5) of producers be-
lieved that the frequency of diseases had not changed. Out
of 87 dairy producers, 10.4% (9/86; IC95%: 7.1–13.8)
reported an increase in the overall disease frequency,
whereas 11.6% (10/86; IC95%: 8.0–15.1) noted a de-
crease. Concerning nonweaned calves, 13.1% (11/84;
IC95%: 9.3–16.9), 20.3% (17/84; IC95%: 15.7–24.7),
8.3% (7/84; 5.2–11.4), and 4.8% (4/84; IC95%:2.4–7.1)
observed increases in diarrhea, respiratory diseases,
septic arthritis, and omphalitis, respectively. Conversely,
17.4% (15/86; IC95%: 13.5–22.1), 17.8% (15/84;
IC95%: 13.5–22.1), 10.7% (9/84; IC95%: 7.2–14.1), and
10.7% (9/84; IC95%: 7.2–14.1) noted decreases in the
frequency of the same diseases. Among weaned heifers,
13.1% (11/84; IC95%: 9.3–16.9) perceived an increase
in respiratory diseases, whereas 15.5% (13/84; IC95%:
11.4–19.5) reported a decrease. Concerning lactating
cows, 13.9% (12/86; IC95%: 10.1–17.8), 25.6% (22/86;

IC95%: 20.7–30.4), 14.0% (12/867; IC95%: 10.1–17.8),
12.8% (11/86; IC95%: 10.1–16.1), and 12.8% (11/86;
IC95%: 10.1–16.1) indicated an increase in the frequen-
cy of reproductive diseases, clinical mastitis, respiratory
diseases, diarrhea, and footrot respectively. Conversely,
13.9% (12/86; IC95%: 10.1–17.8), 18.6% (16/86;
IC95%: 14.3–22.9), 18.6% (16/86; IC95%: 14.3–18.6),
8.1% (7/86; IC95%: 5.1–11.1), and 10.4% (9/86; IC95%:
7.1–13.9) observed decreases in the frequency the same
diseases. For other diseases affecting nonweaned calves,
weaned heifers, and adult cows, less than 30 producers
responded to the question or less than 10% of producers
noticed improvements or worsening in the cure rates.

In the postregulation period, 72.4% (63/87; IC95%: 67.5–77.3) out of the 87 producers expressed overall satisfaction with the new regulation (Figure 5). However, 40.2% (35/87; IC95%: 34.8–45.6) of producers perceived an increase in the complexity of their daily
<figure><img src="image_12.png" /><figcaption>**Figure 3.** Perceptions of 87 dairy producers about the cure rate of major diseases of nonweaned calves, weaned heifers and adult cows after the implementation of a regulation restricting the use of very high importance antimicrobials in animal production in the province of Québec, Canada.</figcaption></figure>

routine (Figure 5), and 67.8% (59/87; IC95%: 62.7–72.9) of producers believed that it had changed their on-farm practices (Figure 5).

## Availability of AM

In general, after the implementation of the new regulation, 42.5% (37/87; IC95%: 31.9–53.1) of producers reported that they had to use a second or third choice of AM due to the unavailability of first choice AM. This led to 10.8% (4/37; IC95: 0.8–20.8) of them sometimes replacing a category II AM with a category I AM, and 13.5% (5/37; IC95%: 2.5–24.5) of them replacing a category III AM with a category II AM. A total of 49.4% (43/87; IC95%: 38.7–60.1) of producers stated that they rarely (13.8%, 12/87) or never (35.6%, 31/87) faced problems with the availability of AM whereas 48.3% (42/87; IC95%: 37.0–59.6) of producers stated that they occasionally (28.7%) or often (19.5%) faced problems with the availability of AM. Two producers did not answer these questions for unknown reasons (missing data). As they did not answer the question, we considered that they did not have a problem with the availability of AM (they were classified with the producers who responded “never”).

## DISCUSSION

The objective of this study was to describe changes in knowledge and on-farm practices among dairy producers, while also providing insights into the perceived effects

following the implementation of a regulation restricting the use of category I AM in the food animal industry in the province of Québec, Canada. To our knowledge, limited studies have assessed the effects of measures aimed at reducing AMU in dairies. In this study, dairy producers were administered the preregulation questionnaire without prior information about the impending regulation. This approach ensured their responses remained unaffected by awareness of the upcoming changes regarding AMU.

## Knowledge

We hypothesized that following the implementation of the regulation, producers' understanding of the categorization of AM based on their importance for human medicine would increase. Specifically, it was anticipated that producers would acquire a more discerning knowledge of which AM fell under category I and which did not because this regulation specifically targets category I AM. Our findings indeed described an increase in producers' knowledge regarding the categorization of category I AM when compared with the preregulation period. One possible explanation is the effect of the regulation itself. Because producers had to limit their use of category I AM, they likely acquired the skills to distinguish them from other AM. Another possible contributing factor to this result is the growing number of producers who underwent a training course about judicious AMU. Indeed, the provincial veterinary association, in collaboration with experts from the Université de Montréal, developed
<figure><img src="image_13.png" /><figcaption>**Figure 4.** Perceptions about the change in the frequency of major diseases of calves, weaned heifers and adult cows in 87 dairy farms after the implementation of a regulation restricting the use of antimicrobials of very high importance for human medicine in animal production in the province of Québec, Canada.</figcaption></figure>

a 3-h course and enlisted trained local veterinarians to deliver it. The primary objective was to educate dairy producers on the responsible and appropriate use of AM. The course emphasized on the significance of targeted therapy for specific diseases such as retained placenta, metritis, mastitis, respiratory diseases, lameness, and calf diarrhea (Roy et al., 2020). Surprisingly, we found a similar mean reduction in the number of mistakes (based on the knowledge score difference between pre- and postregulation questionnaires) among producers who did not attend the training course and those who did. This similarity suggests that the training alone might not have affected the knowledge score among the participants. Producers might also have increased their knowledge through various means other than the training course, such as participating in conferences, referring to publications, collaborating with colleagues, or consulting with their veterinarian. Therefore, further investigation is necessary to comprehensively understand how producers acquire information on AMU and AMR. Additionally, the producers who participated in this study were chosen based on their proximity to the veterinary faculty. They had easy access to veterinary care. They were also participating in an extensive AMU and AMR monitoring study. Therefore, they were possibly more educated about AMU and AMR in general then producers in remote areas. Assessing the knowledge levels of producers in remote areas could provide valuable insights into the dissemination of information in these regions. Understanding these influential factors is crucial for developing more effective

strategies to enhance producers' awareness and practices regarding AMU and AMR. Education plays a pivotal role in increasing awareness, and heightened awareness can foster greater motivation for behavioral changes.

## On-Farm Practices

On-farm practices were a focal point of our study, guided by several hypotheses. Initially, we postulated that because category I AM were predominantly used for treating mastitis and respiratory diseases, there would be a notable shift toward choosing category II AM after the regulation for these conditions. We expected veterinarians to play a pivotal role in educating and encouraging producers not only to reduce the use of category I AM but also to promote other alternative practices aimed at reducing overall AMU. Therefore, we anticipated an increase in the adoption of selective dry cow therapy methods, driven by the necessity for certain producers to reduce their reliance on category I AM and explore alternative approaches. We also hypothesized an increased awareness and application of teat sealants among producers as an additional measure to mitigate AMU, considering their integral role in selective dry cow therapy protocols. Moreover, we hypothesized that the use of diagnostic tests and systemic signs as criteria to use AM would increase.

The study's findings suggest several significant changes in on-farm daily practices related to AMU. Thus, there appears to be a shift from choosing category
I AM as primary treatment toward category II AM for clinical mastitis and reproductive diseases. Category II AM are of lesser importance for human medicine. This finding is consistent with the research conducted by Millar et al. (2022), demonstrating a significant decrease in the sales of category I AM across more than 3,337 dairy farms in the province after the implementation of the regulation, accounting for ~70% of the dairy farms Millar et al., 2022). As mentioned previously, before the regulation, 15% of AM used in the dairy sector were category I AM, mainly consisting of intramammary and injectable formulations (Lardé et al., 2021). Notably, a third-generation cephalosporin (category I AM) was the only AM available without a milk withdrawal period, making it a very convenient choice before the regulation. Surprisingly, we did not observe an increase proportion of producers who reported choosing a category II AM as the main treatment of respiratory diseases in youngstock and adult cows. It is important to note, however, that only 23 producers reported choosing a category I AM as main treatment before the implementation of the regulation. Among them, 11 stated that they did not treat respiratory diseases with any treatment after the implementation, whereas 12 mentioned choosing a category II AM instead. Consequently, the sample size may have been too small to detect any significant difference. Nevertheless, it is worth mentioning that no producers indicated choosing a category I AM as their primary treatment for respiratory diseases after the implementation of regulation, which is a positive outcome. Moreover, it is important to note that these data represent the producers self-reported primary

treatment for a given disease. Acknowledging the potential for recall bias, desirability bias, or confirmability bias in the responses from producers is crucial. The inclination of producers to portray their practices favorably is noteworthy. Briefly, our results suggest a reduction in the proportion of producers indicating choosing a category I and an increase in the proportion of producers indicating choosing a category II AM as the primary treatment of certain diseases. Further investigation is essential to monitor changes in category II AMU over time to prevent unintended consequences such as the emergence of AMR to this category of AM.

Interestingly, we observed a significant increase in the adoption of selective dry cow therapy. Blanket dry cow therapy involves administering an AM treatment to all cows in the herd during the dry period, regardless of their individual udder health status, whereas selective dry cow therapy targets only those cows that have an intramammary infection at dry-off (Kabera et al., 2021). Given the growing concerns surrounding AMR and the overuse of AM, the use of selective dry cow therapy can reduce the use of AM by 66.0% (IC95%: 49.0 – 80.0) when compared with blanket therapy (Kabera et al., 2021). In contrast, it can effectively maintain udder health and milk production without compromising animal welfare only if used simultaneously with teat sealants (Kabera et al., 2021). Most selective dry cow protocols involve placing teat sealants on healthy or all teats to prevent new infections. In our study, we observed no significant increase in the use of teat sealants, and the adoption of selective dry cow therapy remained below 50%. These findings

<figure><img src="image_14.png" /><figcaption>**Figure 5.** Level of agreement in 87 dairy producers about different statements regarding the implementation of a regulation restricting the use of antimicrobials of very high importance for human medicine in the province of Québec, Canada.</figcaption></figure>
may be attributed to various factors influencing producers' attitudes toward these practices, such as their level of education, perceived time commitment, risk perceptions, and economic considerations (Scherpenzeel et al., 2016).

Despite the significant increase in the use of diagnostic tests for clinical mastitis, less than 50% of producers reported using them. A study by Millar et al. (2023) highlighted that the distance between farms and veterinary clinics, as well as delays in receiving test results, acted as barriers to the implementation of diagnostic tests on farms. Therefore, improving access to rapid diagnostic test results on farms is imperative (Nobrega et al., 2020). Establishing small laboratories on farms could also be considered as an option to reduce the delays between sampling and test results (Zeineldin et al., 2021). Moreover, in our study, few producers reported that they were using systemic signs such as fever to guide treatment decisions. Many scale health scoring systems incorporate fever as an important factor in determining whether an animal requires treatment (Berge et al., 2009; Uyama et al., 2022). Therefore, further training and enhanced communication efforts are warranted in this regard. Overall, all these findings concerning changes in daily practices on farms suggest a shift toward more targeted and prudent AMU within the dairy animal industry. It is essential to sustain efforts to promote the judicious use of AM and the adoption of selective dry cow therapy in combination with teat sealants, and to continue to enhance producers' use of the decision criteria for initiating treatments of diseases.

## Perceived Effects and Availability of AM

For this study, we supposed that there would be a perceive increase the frequency of disease and the cure rates would remain unchanged. It is important to highlight that it was self-reported effects. As in another study, the perceptions of certain producers may have been influenced by their beliefs, with many expressing concerns that the regulation would lead to increased diseases frequencies and have economic consequences (Millar et al., 2023). This could have led to an overestimation of the number of cases, introducing both confirmation and desirability bias into their responses (Schumm, 2021).

According to the producers' perceptions, the frequency of most diseases of youngstock and cows did not change, and the cure rate remained the same. It's worth noting that a significant number of producers could not estimate the cure rate, emphasizing that these results originated from subjective perceptions. However, some producers believed that the frequency of clinical mastitis had increased and that the cure rate had worsened. One possible explanation for these results is the discontinuation of a specific intramammary formulation containing a

category I AM after the regulation's implementation; an intramammary product containing 4 AM (penicillin G procaine, dihydrostreptomycin, novobiocin, and polymyxin B sulfate) combined with hydrocortisone acetate, and hydrocortisone sodium succinate, which was commonly used to treat clinical mastitis. The addition of the hydrocortisone component often resulted in rapid reduction of redness and inflammation, giving producers the impression that the clinical mastitis had been successfully resolved. Moreover, ~50% of producers faced challenges in accessing AM. Indeed, following the implementation of the new regulation, various AM (e.g., those used for clinical mastitis and dry-off treatments, injectable ampicillin, and all short action injectable tetracyclines) were unavailable or discontinued for various reasons, including commercial decisions and the effect of the COVID-19 pandemic. As alternative treatments to category I AM may not have been readily available, this situation may have potentially affected the cure rate of clinical mastitis or other infections. Obtaining data on disease frequency on farms poses a challenge in Canada. Producers must maintain disease records on their farms under the pro-Action initiative, a national quality assurance program for the Canadian dairy sector (Dairy Farmers of Canada, 2023). However, not all producers accurately complete these records, and no centralized database exists, making data not easily accessible (Lardé et al., 2021). Enhancing animal disease surveillance would facilitate access to more accurate data on diseases' frequency. Further studies are needed to evaluate the consequences of AMU restrictions on animal health and well-being (Collineau et al., 2017; Tang et al., 2019b).

## Lessons Learned from Québec's Case

Lessons learned from Québec's case reveal both successes and challenges in the implementation of regulations aimed at reducing AMU within the dairy industry. Although the regulation has indeed led to a significant reduction in the utilization of Category 1 AM within the province (Millar et al., 2022), its execution has encountered barriers, as highlighted by Millar et al. (2023). Negative perceptions among producers, feelings of injustice compared with other provinces, alongside concerns regarding animal welfare, have presented significant barriers to the adoption of the regulation. Despite these challenges, this study underscores a shift in producers' practices toward more judicious AMU practices. However, sustaining and enhancing this momentum requires further efforts, particularly in motivating producers to adopt new practices. Effective measures should consider the socio-economic context, recognizing the myriad factors influencing producers' decisions. Moreover, the scarcity of data on the effects of measures aimed at cur-
tailing AMU poses a significant challenge. The lack of comprehensive data on the effect of a regulation is potentially an obstacle to the efforts to motivate producers toward compliance with regulations. Hence, additional research efforts are imperative to fully understand the true effect on disease frequency, which could serve as a significant motivator for producers.

## Limitations

This study has several limitations that require careful consideration. First, relying on producers' perceptions introduces the potential for recall bias, where their memory of specific information may influence outcomes in various ways. Additionally, desirability and confirmation biases may have affected the recollection process, potentially emphasizing certain information while neglecting others. Furthermore, the use of Likert-scale questions poses a limitation, as the interpretation of distance between each value may vary among producers. This discrepancy could affect the accuracy and consistency of responses, warranting caution in the interpretation of results. However, Likert scales provide a structured approach to measuring attitudes and perceptions, allowing for quantitative analysis and comparison across respondents (Pell, 2005; Willits et al., 2016). Despite these limitations, they remain a widely used tool in social science research due to their ease of administration and ability to quantify attitudes and perceptions.

Moreover, the aim of this study was to describe the changes in practices among dairy producers following the implementation of a regulation. However, it is essential to clarify that the estimates provided do not arise from an examination of associations, and we did not control for confounding variables. Thus, it remains inconclusive whether the observed changes directly resulted from the regulation or were influenced by other factors.

Another noteworthy limitation is the computation of the AM knowledge score, as the exclusion of 7 producers might result in an overestimation of the overall score. However, including them could also have introduced a bias, as they did not respond to the question in the postregulation questionnaire, whereas in the preregulation questionnaire, some of these producers did make efforts to categorize some of the AM. Furthermore, the slightly different structure of the 2 questionnaires represents a significant limitation. These changes may have influenced the interpretation of the questions by some producers, thereby potentially limiting the accuracy of the results. Selection bias is also a concern, as producers engaged in both questionnaires may have had heightened awareness due to their involvement in a broader project focusing on AMR and AMU. Furthermore, the subset of producers from 3 specific regions of Québec may not

entirely represent the diversity of producers across the province.

## CONCLUSIONS

This study has described significant increase in knowledge and significant changes of on-farm practices following the implementation of a regulation restricting the use of category I AM in the province of Québec, Canada. A shift toward choosing a category II AM as the primary treatment for reproductive diseases and clinical mastitis was observed. The adoption of selective dry cow therapy increased, alongside an increased use of diagnostic test for mastitis. However, we observed no change in the use of teat sealants and, for most diseases, and we observed no increase in the use of systemic signs as decision criteria to treat animals with AM. Although some producers reported minimal effects on disease frequency, a subset perceived an increase the frequency of clinical mastitis and reproductive diseases. The case of Québec serves as a valuable example for understanding the necessary steps to reduce AMU. Addressing the challenges encountered while capitalizing on the successes achieved so far is necessary in navigating the complexities of changing long-standing AMU habits.

## NOTES

Author NM was supported during this work by scholarships from the NSERC-CREATE in Milk Quality Program (465641-2015), and from CRSNG (BESC D-579128-2023; Ottawa, Canada). Agriculture and Agri-Food Canada (Ottawa, Canada) et ministère de l'Agriculture, des Pêcheries et de l'Alimentation (Québec, Canada), Programme Innov'Action (IA119542 et IA115330; Québec, Canada) also financed this project. The research team sincerely thank all producers who participated in this study. Without them, we would not have been able to do this work on the effect of the regulation restricting the use of category I AM in dairies. Also, the authors thank Catherine Dupuis-Bernier, Laurence Desjardins, and Sandra Botelho for their help in entering the data in a Microsoft Access Database before analysis. Supplemental material for this article is available at https://doi.org/10.6084/m9 figshare.26087929 (File S1) and https://doi.org/10.6084/m9 figshare.26087932.v1 (File S2). The author contributions were as follows: HL, CA, MDL, SD, DF, and JPR contributed to the conception and design of the study; HL, JM, and MDL collected data; NM analyzed the data and wrote the first draft of the manuscript. All authors contributed to the revision of the manuscript. Ethical approval was obtained from the Comité d'éthique de la recherche en santé (CERES) of the Université de Montréal for data collection preregula-
tion (16–163-CERES-D), and from the Comité d’éthique
de la recherche en sciences et en santé (CERSES) of the
Université de Montréal for data collection postregulation
(CERSES-21–006-D). The authors have not stated any
conflicts of interest.

Nonstandard abbreviations used: AM = antimicrobials; AMR = antimicrobial resistance; AMU = antimicrobial use; IC95% = CI; MAPAQ = Ministère de l'Agriculture, des Pêcheries et de l'Alimentation du Québec; Q1 = first quartile; Q3 = third quartile; t-value = a ratio of the difference between the mean of the 2 sample sets and the variation that exists within the sample sets.

REFERENCES

Aarestrup, F. M. 2015. The livestock reservoir for antimicrobial resistance: A personal view on changing patterns of risks, effects of interventions and the way forward. Philos. Trans. R. Soc. Lond. B Biol. Sci. 370:20140085. https://doi.org/10.1098/rstb.2014.0085.

Aenishaenslin, C., B. Häsler, A. Ravel, J. Parmley, K. Stärk, and D. Buckeridge. 2019. Evidence needed for antimicrobial resistance surveillance systems. Bull. World Health Organ. 97:283–289. https://doi.org/10.2471/BLT.18.218917.

Agriculture et Agroalimentaire Canada. 2021. Overview of Canada's Dairy Industry [WWW Document]. Government of Canada. Accessed Apr. 28, 2023. https://agriculture.canada.ca/.

Berge, A. C. B., D. A. Moore, T. E. Besser, and W. M. Sischo. 2009. Targeting therapy to minimize antimicrobial use in preweaned calves: Effects on health, growth, and treatment costs. J. Dairy Sci. 92:4707–4714. https://doi.org/10.3168/jds.2009-2199.

Collineau, L., C. Rojo-Gimeno, A. Léger, A. Backhans, S. Loesken, E. O. Nielsen, M. Postma, U. Emanuelson, E. Beilage, M. Sjölund, E. Wauters, K. D. C. Stärk, J. Dewulf, C. Belloc, and S. Krebs. 2017. Herd-specific interventions to reduce antimicrobial usage in pig production without jeopardising technical and economic performance. Prev. Vet. Med. 144:167–178. https://doi.org/10.1016/j.prevetmed.2017.05.023.

Coyne, L. A., G. L. Pinchbeck, N. J. Williams, R. F. Smith, S. Dawson, R. B. Pearson, and S. M. Latham. 2014. Understanding antimicrobial use and prescribing behaviours by pig veterinary surgeons and farmers: A qualitative study. Vet. Rec. 175:593. https://doi.org/10.1136/vr.102686.

Dadgostar, P. 2019. Antimicrobial resistance: Implications and costs. Infect. Drug Resist. 12:3903–3910. https://doi.org/10.2147/IDR.S234610.

Dairy Farmers of Canada. 2023. ProAction [WWW Document]. ProAction. Accessed Feb. 6, 2023. http://www.dairyfarmers.ca/proaction.de_Lagarde,M.,J. M.Fairbrother,M. Archambault,S. Dufour,D. Francoz,J. Massé,H. Lardé,C. Aenishaenslin,M.-È. Paradis,and J.-P. Roy. 2022. Impact of a regulation restricting critical antimicrobial usage on prevalence of antimicrobial resistance in *Escherichia coli* isolates from fecal and manure pit samples on dairy farms in Québec, Canada. Front. Vet. Sci. 9:838498. https://doi.org/10.3389/fvets.2022.838498.

Gerber, M., S. Dürr, and M. Bodmer. 2021. Reducing antimicrobial use by implementing evidence-based, management-related prevention strategies in dairy cows in Switzerland. Front. Vet. Sci. 7:611682. https://doi.org/10.3389/fvets.2020.611682.

Golding, S. E., J. Ogden, and H. M. Higgins. 2019. Shared goals, different barriers: A qualitative study of UK veterinarians' and farmers' beliefs about antimicrobial resistance and stewardship. Front. Vet. Sci. 6:132. https://doi.org/10.3389/fvets.2019.00132.

Government of Canada. 2017. Responsible use of medically important antimicrobials in animals. Accessed Jan. 9, 2020. https://www.canada.ca/en/public-health/services/antibiotic-antimicrobial-

-resistance/animals/actions/responsible-use-antimicrobials.html.

Kabera, F., J.-P. Roy, M. Afifi, S. Godden, H. Stryhn, J. Sanchez, and S. Dufour. 2021. Comparing blanket vs. selective dry cow treatment approaches for elimination and prevention of intramammary infections during the dry period: A systematic review and meta-analysis. Front. Vet. Sci. 8:688450. https://doi.org/10.3389/fvets.2021.688450.

Lardé, H., S. Dufour, M. Archambault, D. Léger, D. Loest, J.-P. Roy, and D. Francoz. 2020. Assignment of Canadian defined daily doses and Canadian defined course doses for quantification of antimicrobial usage in cattle. Front. Vet. Sci. 7:10. https://doi.org/10.3389/fvets.2020.00010.

Lardé, H., S. Dufour, M. Archambault, J. Massé, J.-P. Roy, and D. Francoz. 2021. An observational cohort study on antimicrobial usage on dairy farms in Quebec, Canada. J. Dairy Sci. 104:1864–1880. https://doi.org/10.3168/jds.2020-18848.

Légis du Québec, 2019. Légis du Québec, Loi sur la protection sanitaire des animaux, Chapitre P-42

Leung, E., D. E. Weil, M. Raviglione, and H. Nakatani. 2011. The WHO policy package to combat antimicrobial resistance. Bull. World Health Organ. 89:390–392. https://doi.org/10.2471/BLT.11.088435.

Lhermie, G., P. Sauvage, L. W. Tauer, L. V. Chiu, K. Kanyiamattam, A. Ferchiou, D. Raboisson, H. M. Scott, D. R. Smith, and Y. T. Grohn. 2020. Economic effects of policy options restricting antimicrobial use for high risk cattle placed in U.S. feedlots. PLoS One 15:e0239135. https://doi.org/10.1371/journal.pone.0239135.

Massé, J., H. Lardé, J. Fairbrother, J.-P. Roy, D. Francoz, S. Dufour, and M. Archambault. 2021. Prevalence of antimicrobial resistance and characteristics of *Escherichia coli* isolates from fecal and manure pit samples on dairy farms in the province of Québec, Canada. Front. Vet. Sci. 8:654125. https://doi.org/10.3389/fvets.2021.654125.

McEwen, S. A., F. J. Angulo, P. J. Collignon, and J. M. Conly. 2018. Unintended consequences associated with national-level restrictions on antimicrobial use in food-producing animals. Lancet Planet. Health 2:e279–e282. https://doi.org/10.1016/S2542-5196(18)30138-4.

McKernan, C., T. Benson, S. Farrell, and M. Dean. 2021. Antimicrobial use in agriculture: Critical review of the factors influencing behaviour. JAC Antimicrob. Resist. 3:dlab178. https://doi.org/10.1093/jacamr/dlab178.

Millar, N., C. Aenishaenslin, H. Lardé, J.-P. Roy, C. Fourichon, D. Francoz, M.-È. Paradis, and S. Dufour. 2022. Evidence of a decrease in sales of antimicrobials of very high importance for humans in dairy herds after a new regulation restricting their use in Quebec, Canada. Zoonoses Public Health 69:370–381. https://doi.org/10.1111/zph.12929.

Millar, N., S. Dufour, H. Lardé, J.-P. Roy, C. Belloc, D. Francoz, M.-È. Paradis, M. Archambault, J.-M. Fairbrother, and C. Aenishaenslin. 2023. Barriers and facilitators to implementing a new regulation restricting antimicrobial use in dairy production in Québec, Canada: A qualitative study. Front. Vet. Sci. https://doi.org/10.3389/fvets.2023.1025781.

Nobrega, D. B., S. A. Naqvi, S. Dufour, R. Deardon, J. P. Kastelic, J. De Buck, and H. W. Barkema. 2020. Critically important antimicrobials are generally not needed to treat nonsevere clinical mastitis in lactating dairy cows: Results from a network meta-analysis. J. Dairy Sci. 103:10585–10603. https://doi.org/10.3168/jds.2020-18365.

Pell, G. 2005. Use and misuse of Likert scales. Med. Educ. 39:970. https://doi.org/10.1111/j.1365-2929.2005.02237.x.

Roy, J.-P., M. Archambault, A. Desrochers, J. Dubuc, S. Dufour, D. Francoz, M.-È. Paradis, and M. Rousseau. 2020. New Quebec regulation on the use of antimicrobials of very high importance in food animals: Implementation and impacts in dairy cattle practice. Can. Vet. J. 61:193–196.

Scherpenzeel, C. G. M., S. H. W. Tijs, I. E. M. den Uijl, I. M. G. A. Santman-Berends, A. G. J. Velthuis, and T. J. G. M. Lam. 2016. Farmers' attitude toward the introduction of selective dry cow therapy. J. Dairy Sci. 99:8259–8266. https://doi.org/10.3168/jds.2016-11349.

Schumm, W. R. 2021. Confirmation bias and methodology in social science: An editorial. Marriage Fam. Rev. 57:285–293. https://doi.org/10.1080/01494929.2021.1872859.
Tang, K. L., N. P. Caffrey, D. B. Nóbrega, S. C. Cork, P. E. Ronksley, H. W. Barkema, A. J. Polachek, H. Ganshorn, N. Sharma, J. D. Kellner, S. L. Checkley, and W. A. Ghali. 2019a. Comparison of different approaches to antibiotic restriction in food-producing animals: Strati-fied results from a systematic review and meta-analysis. *BMJ Glob. Health* 4:e001710. https://doi.org/10.1136/bmjgh-2019-001710.

Tang, K. L., N. P. Caffrey, D. B. Nóbrega, S. C. Cork, P. E. Ronksley, H. W. Barkema, A. J. Polachek, H. Ganshorn, N. Sharma, J. D. Kellner, S. L. Checkley, and W. A. Ghali. 2019a. Examination of unintended consequences of antibiotic use restrictions in food-producing animals: Sub-analysis of a systematic review. *One Health* 7:100095. https://doi.org/10.1016/j.ohcalt.2019.100095.

Tang, K. L., N. P. Caffrey, D. B. Nóbrega, S. C. Cork, P. E. Ronksley, H. W. Barkema, A. J. Polachek, H. Ganshorn, N. Sharma, J. D. Kellner, and W. A. Ghali. 2017. Restricting the use of antibiotics in food-producing animals and its associations with antibiotic resistance in food-producing animals and human beings: A systematic review and meta-analysis. *Lancet Planet. Health* 1:e316–e327. https://doi.org/10.1016/S2542-5196(17)30141-9.

Uyama, T., D. F. Kelton, E. I. Morrison, E. de Jong, K. D. McCubbin, H. W. Barkema, S. Dufour, J. Sanchez, L. C. Heider, S. J. LeBlanc, C. B. Winder, J. T. McClure, and D. L. Renaud. 2022. Cross-sectional study of antimicrobial use and treatment decision for preweaning Canadian dairy calves. *JDS Commun.* 3:72–77. https://doi.org/10.3168/jdsc.2021-0161.

Visschers, V. H. M., A. Backhans, L. Collineau, D. Iten, S. Loesken, M. Postma, C. Belloc, J. Dewulf, U. Emanuelson, E. Beilage, M.

Siegrist, M. Sjölund, and K. D. C. Stärk. 2015. Perceptions of anti-microbial usage, antimicrobial resistance and policy measures to reduce antimicrobial usage in convenient samples of Belgian, French, German, Swedish and Swiss pig farmers. *Prev. Vet. Med.* 119:10. https://doi.org/10.1016/j.prevetmed.2015.01.018.

Willits, F. K., G. L. Theodori, and A. E. Luloff. 2016. Another look at Likert scales. *J. Rural Soc. Sci.* 31:6. https://egrove.olemiss.edu/jrss.vol31/iss3/6/.

Zeineldin, M., A. A. Elolimy, P. R. K. Reddy, M. Abdelmegeid, M. Mel-lado, M. M. M. Y. Elghandour, and A. Z. M. Salem. 2021. On-farm point-of-care diagnostic technologies for monitoring health, welfare, and performance in livestock production systems. Pages 209–232 in *Sustainable Agriculture Reviews* 54: Animal Biotechnology for Livestock Production 1, Sustainable Agriculture Reviews. V.K. Yata, A.K. Mohanty, and E. Lichtfouse, ed. Springer International Publishing. https://doi.org/10.1007/978-3-030-76529-3_7

ORCIDS

Nikky Millar https://orcid.org/0009-0008-9794-7933

Simon Dufour https://orcid.org/0000-0001-6418-0424

Hélène Lardé https://orcid.org/0000-0002-8742-8303

Jonathan Massé https://orcid.org/0000-0002-4583-8515

Marie Archambault https://orcid.org/0000-0002-5206-9531

Jean-Philippe Roy https://orcid.org/0000-0002-0444-2303

David Francoz https://orcid.org/0000-0002-1634-0507