Despite the global adoption of the FAIR guiding principles, significant barriers remain in their practical implementation due to the lack of domain-specific standards for “rich metadata”. While generic metadata schemes provide basic information, they often fail to capture the complexity of data quality and the nuances of specialized scientific fields. This gap is particularly evident in veterinary epidemiology, a field characterized by complex, multi-scale data spanning various domains where detailed description of data analysis and modelling tend to be prioritized over raw data description, leading to inconsistent reporting and low data reusability. This paper introduces the first community-developed rich metadata guidelines specifically designed for veterinary epidemiology datasets, accompanied by practical templates and real-world examples. By integrating existing standards with specific guidance on domain-specific attributes and data quality, these guidelines provide a comprehensive, single-source framework accessible to researchers across academic, public, and private sectors. They aim to support researchers and stakeholders in enhancing the reusability of animal health data.

Dairy-beef and veal production play an important role in the North American beef supply, relying almost entirely on surplus calves that are marketed at a young age from dairy farms. However, suboptimal health conditions and improper management, due to their lack of a substantial role in dairy production and limited economic returns, have drawn public attention to the issue of surplus calves. To facilitate optimal care for these calves, crossbreeding and on-farm dairy-beef production have been promoted as strategies to increase the economic value of surplus calves. The objectives of this study were to describe current surplus calf marketing practices, the rationale behind these practices, and any differences between the breeding strategies employed by dairy farmers who raised and finished dairy-beef animals on their farms (referred to as "dairy-beef producers") and those who did not ("non-dairy-beef producers"). An online survey was completed by 70 dairy producers in Atlantic Canada; 66 of these dairy producers answered sufficient questions to be classified as dairy-beef producers or non-dairy-beef producers. There was a moderate number of dairy-beef producers (24.2%) in Atlantic Canada, although most dairy-beef and non-dairy-beef producers marketed some of their surplus calves before weaning (97.0%). On-farm resource availability (i.e., housing, labor, and feeding capacities) and economic factors (i.e., production costs, profitability, quick earnings, and dairy-beef demand) were the primary considerations among producers that influenced their marketing practices. Additionally, the use of sexed frozen dairy semen (43.8%-72.0%) and unsexed frozen beef semen (78.0%-93.08%) on dairy cattle was common among producers, with Aberdeen Angus being the most commonly used breed for crossbreeding (89.5%). The results highlight that dairy producers consider on-farm resource availability and economic factors when managing and marketing surplus calves. Crossbreeding and the use of sexed semen seem to be widely adopted on farms in Atlantic Canada, and on-farm dairy-beef production could be a viable secondary business for some dairy producers in the near future.

The aim of this study was to compare the microbiota diversity captured in individual versus pooled fecal samples from dairy cattle and evaluate the feasibility of using pooled sampling to assess the microbiota of dairy cattle at the herd level. A cross-sectional study used animals from 28 Prince Edward Island (PEI) dairy farms in Canada. The farms were visited between July and December 2020. Both free-stall and tie-stall housing systems were eligible. Manure samples from dry and lactating cows were obtained. Then, approximately 20g of fecal samples from each group were pooled. DNA extractions on all subsamples were performed using the Qiagen PowerMax Soil Kit and submitted for 16S rRNA gene amplification and sequencing. Operational taxonomic units were determined, and four alpha diversity indices were computed. A total of 128 and 132 manure samples from pos and prepartum cows, respectively, were analyzed. Mixed-effects random slope models were employed, incorporating herd-level random effects to estimate the correlation among individual samples and between individual and pooled samples. The estimated Shannon observed features, Pielou evenness and Faith PD were 5.9, 580, 0.93 and 44.1 from the individual and 5.93, 587, 0.93 and 45.5 from the pooled samples, respectively. All alpha diversity metrics were not significantly different between individual and pooled samples. Overall, pooled sampling does not significantly affect diversity and provides comparable results with individual samples, though it tends to show slightly higher diversity in some indices. This sampling strategy could be used in microbiota studies of dairy herds. ### Competing Interest Statement The authors have declared no competing interest.

The study aimed to describe pregnancy losses within the same lactation in a large commercial dairy herd in Argentina. A retrospective study was completed using 25,019 lactation records from 11,263 cows with at least 1 artificial insemination-declared pregnant (AIDP) by ultrasound at 28 to 42 d post AI. Each AIDP was identified according to the corresponding parity number, which was sequentially numbered and related to a pregnancy number within the same lactation. In each lactation, the uterine health events (UTE), retention of fetal membranes, puerperal metritis, and clinical endometritis, as well as the nonuterine health events (NUTE), clinical mastitis, and clinical lameness were recorded. The health status for each lactation was categorized according to the site of inflammation, such as healthy cows, cows with UTE, cows with NUTE records, and cows with both UTE and NUTE. Pregnancy loss was defined by: (1) detection of heat with blue paint rubbed off after having been previously diagnosed pregnant and subsequently diagnosed open by ultrasound at the next herd visit 14 d later; (2) observed abortion; or (3) diagnosis open by ultrasound pregnancy diagnosis 5 mo after AI of pregnancy to reconfirm pregnancy status. The occurrence of pregnancy loss was reported for the whole study period and 21-d periods. The risk of pregnancy loss was analyzed using a Cox proportional hazards model that included parity number, AIDP, season, health status, DIM to AIDP, and daily milk production to AIDP as covariates. Herd persistence was used to assess the risk of cows leaving the herd before the next lactation due to pregnancy loss, with the last pregnancy within each lactation, parity number, and pregnancy loss as covariates. The occurrence of pregnancy loss was 22.5%; the occurrence of pregnancy loss per 21 d was 3.7%. The median day of gestation and median DIM for the first, second, and third pregnancy losses were 98, 108, 121 d and 224, 394, and 552 d, respectively. Cows with UTE diseases had a higher hazard of pregnancy loss than healthy cows (hazard ratio [HR] 1.24, 95% CI 1.13-1.36); conversely, cows in second or third parity did not have a higher hazard of pregnancy loss than first parity cows (HR 1.03, 95% CI 0.95-1.11; HR 1.00, 95% CI 0.92-1.08; respectively). Similarly, cows with 2 and 3 AIDP had a lower hazard of pregnancy loss than cows with only 1 AIDP (HR 0.90, 95% CI 0.83-0.97; HR 0.92, 95% CI 0.85-0.99, respectively). Cows with AIDP in fall and winter had a lower HR of pregnancy loss than those with AIDP in summer (HR 0.84, 95% CI 0.77-0.91; HR 0.82, 95% CI 0.75-0.89). In conclusion, health events during lactation affect pregnancy loss within the same lactation and herd persistence to the next lactation in dairy cows. The risk of pregnancy losses within a lactation may not increase with parity number and higher AIDP, but conversely, it may increase with higher milk production (HR 1.02, 95% CI 1.01-1.02; 1%/1 kg increase in test-day milk yield closest to the AIDP).

Dairy heifer replacement programs (RPs) are crucial for herd health and productivity. Understanding the factors that motivate or limit their implementation could go a long way toward promoting these programs more effectively. This study aimed to quantify the relative importance of such factors among dairy farmers and advisors in the west of Buenos Aires (Argentina). For this, a choice experiment was designed using conjoint analysis (CA). The factors included therein were chosen based on the literature and expert discussions. The participants (48 farmers and 41 advisors) were asked to rank nine motivating and nine limiting profiles, i.e. combinations of factors and their corresponding levels, from 1 (most motivating/limiting) to 9 (least motivating/limiting). The part-worth utility value and relative importance of each factor and level was then estimated through ordinary least squares regression. The results showed that motivating and limiting factors had the same relative importance for farmers and advisors when deciding to adopt/recommend improved RPs. The part-worth utilities for different levels were not significantly different from each other in the advisors' rankings (p-values >0.05), but they were significantly different (p-value <0.05) for the farmers within the factors "Expectations", "External support" and "Investments needed". The highest part-worth utility was assigned to having a feasible program to implement. The lowest values corresponded to having access to public and/or private support and having to invest in regular professional advice. These findings are further evidence that the factors driving or hindering the enhancement of dairy farm management are manifold and often farm-specific.

ABSTRACT: The aim of this study was to assess the prevalence and incidence of canine leptospirosis and brucellosis in Parque Francisco de Assis, a shelter in Lavras, Minas Gerais State, Brazil, as well as the risk factors potentially associated with both diseases. Samples of blood, urine, and sera from all animals were collected in 2019 (n = 329) and 2020 (n = 325 dogs). DNA of Leptospira spp. (urine) and Brucella spp. (urine and blood) were searched by PCR, whereas microagglutination test (MAT) and agar gel immunodiffusion assay (AGID) were performed to identify antibodies anti-Leptospira spp. and anti-rough Brucella spp., respectively. The results showed no positive dogs in PCR for Leptospira spp.; however, a seroincidence of 9.24% was found considering MAT results, with Canicola and Autumnalis being the most common serogroups. The incidence of Brucella spp. PCR-positive animals in the 6 months was 5.62% in the urine and 11.23% in the blood samples, while AGID showed a seroincidence of 11.74% in the period. Overall, our results demonstrated the circulation of Leptospira spp. and Brucella spp. among the dogs from Parque Francisco de Assis, Lavras, Minas Gerais, Brazil, being the weight increase (1.10, 95%CI 1.00-1.21) and neutropenia (3.29, 95%CI 1.60-6.77), the risk factors associated with the occurrence of leptospirosis and brucellosis, respectively. Therefore, brucellosis was identified in the dogs of Parque Francisco de Assis, and the presence of antibodies against Leptospira spp. suggesting contact of the dogs with the pathogen, which represent a risk for the other animals and to the humans in close contact with the positive dogs.

BACKGROUND:Infectious salmon anemia virus is one of the most important pathogens responsible for causing infectious salmon anemia in Atlantic salmon (Salmo salar). Following its first emergence in 1980s in Norway, it has been reported in several salmon producing countries worldwide, with new variants frequently reported. These variants mostly exhibit differences in segments 5 and 6 of the genome, which contribute to the genetic diversity and variability in virulence. Despite the considerable economic losses associated with ISA, there remains a critical gap in available information on genetic diversity and classification. This study aims to provide a comprehensive and up-to-date synopsis of all known ISAV variants worldwide. METHODS:The Population, Concept, Context approach was used to formulate the research primary question. The primary research question of this review is "What variants of ISAV with respect to segment 5 and 6 has been identified globally in Atlantic salmon?" To address this question, four databases: PubMed, CAB Abstracts via (EBSCO host), Scopus, and the Earth, Atmospheric & Aquatic Science Collection via ProQuest will be used for primary literature search with no language and geographical area restrictions. Studies will be screened using predefined inclusion and exclusion criteria and will be imported in COVIDENCE. Two co-authors will independently screen, extract data, and assess the selected studies. Any discrepancies between the authors will be resolved with the assistance of two other co-authors in each stage of the protocol. DISCUSSION:To the best of our knowledge, this protocol outlines the first scoping review which will provide insights into the genetic diversity of ISAV, offering a comprehensive overview of the reported variants and their distribution globally. These findings could enhance our understanding of the genetic diversity of the virus, help customize mitigation strategies based on variants involved and provide foundation to develop a universally accepted nomenclature system.

Accurate classification of gonadal maturity stages is essential to ensure reliable estimates of reproductive indicators. In Peruvian anchovy (Engraulis ringens), two gonadal maturity scales have been used: the empirical scale proposed by Einarsson et al. (1966) and the histologically validated scale developed by Buitrón et al. (2015). The adoption of this scale underscores the need to harmonize or retrospectively adjust historical maturity records, which is essential for analysing long-term changes in anchovy reproductive dynamics. In this study, we evaluate the efficacy of the gonadosomatic index (GSI) in predicting stages and groups of gonadal maturity. Data from 115 research surveys conducted between 1984 and 2022 were analysed. Classification models using different algorithms were applied, with the random forest algorithm demonstrating the highest accuracy and robustness, achieving a mean accuracy of >90% and a logarithmic loss of 0.13. GSI and total length were identified as the most influential predictors of gonadal maturity. The classification of historical data (1984–2014) using the M-5 model (which includes GSI, total length, latitude, distance from the coast and condition factor) demonstrated high concordance with the reproductive patterns observed in recent periods (2015-2022), supporting its predictive reliability. The results indicate that the combined use of GSI and machine learning-based classification models is a valuable tool for identifying gonadal maturity stages from historical data and harmonizing them with the current maturity scale, facilitating the interpretation of variations in the reproductive behaviour of the resource over time.

An inherent issue to the Atlantic salmon aquaculture production is the possible transmission of infectious pathogens due to the transportation of live fish. This study employed network analysis to model the contribution of Atlantic salmon transfers to the spread of pathogens. We used a publicly available salmon transfer dataset covering the period 2015-2022. Official records showed that 812 transfers of Atlantic salmon occurred between various British Columbian (BC) salmon production units in that timeframe. For the purpose of evaluating changes in the network structure of farmed Atlantic salmon movements, the daily networks were aggregated into two-year periods to generate a time-ordered series of biennial movements. The freshwater hatchery and marine netpen sites comprised the two types of facilities that made up the Atlantic salmon transfer network, which consisted of 99 nodes (facilities) and 350 edges (links) overall. All the networks showed both scale-free and small-world topology, which would encourage the persistence and spread of pathogens in the Atlantic salmon facilities while simultaneously making it easier to develop risk-based surveillance techniques by focusing on high centrality nodes. Additionally, the rare occurrence of high betweenness and reach, presence of disassortative mixing, negative correlation between the in- and out-degree and between ingoing and outgoing infection chain of facilities, and the identification of freshwater hatcheries as potential superspreaders all suggest that Atlantic salmon transfers might not play a significant role in the spread of pathogens between facilities in the British Columbian Atlantic salmon farming industry. Community detection revealed two or three communities persistently in the aquaculture management unit (AMU) level network, and it would be more effective to make zoning based on AMU. In conclusion, targeted surveillance efforts on high-centrality facilities can be employed to combat any infectious outbreak in the BC Atlantic salmon industry caused by live Atlantic salmon movement.

Microbiota analyses are key to understanding the bacterial communities within dairy cattle, but the impact of different storage conditions on these analyses remains unclear. This study sought to examine the effects of freezing at -80°C immediately after collection, refrigeration at 4°C for three days and seven days and absolute ethanol preservation on the microbiota diversity of pooled fecal samples from dairy cattle. Examining 16S rRNA gene sequences, alpha (Shannon, Pielou evenness, observed features and Faith PD indices) and beta (Bray-Curtis, βw and Weighted UniFrac) diversity were assessed. The effects of storage conditions on these metrics were evaluated using linear mixed models and PERMANOVA, incorporating the farm as a random effect. Our findings reveal that 7d and E significantly altered the Shannon index, suggesting a change in community composition. Changes in Pielou evenness for 3d and 7d storage when compared to 0d were found, indicating a shift in species evenness. Ethanol preservation impacted both observed features and Faith PD indices. Storage conditions significantly influenced Bray-Curtis, βw, and Weighted UniFrac metrics, indicating changes in community structure. PERMANOVA analysis showed that these storage conditions significantly contributed to microbiota differences compared to immediate freezing. In conclusion, our results demonstrate that while refrigeration for three days had minimal impact, seven days of refrigeration and ethanol preservation significantly altered microbiota analyses. These findings highlight the importance of sample storage considerations in microbiota research.

This retrospective study aimed to evaluate the performance of hormone treatment protocols, determine the factors associated with pregnancy success after hormone treatment, and compare the cost-efficiencies of two types of hormone treatment among cyclic and noncyclic anestrous dairy cows. The clinical records of 279 anestrous cows that received hormone treatment for artificial insemination (AI) from 64 herds in the western region of Thailand were obtained from Kasetsart University Veterinary Teaching Hospital from January to August 2017. The performance of the hormone treatment protocols, fixed-time AI (TAI) and estrus detection before AI (EAI), showed that the pregnancy risk for the TAI protocol was higher than that for the EAI protocol, but pregnancy per AI did not differ significantly between the two protocols in cyclic and noncyclic cows. Multivariate logistic regression analysis showed that cows receiving the TAI protocol were more likely to be pregnant compared to those treated with the EAI protocol. Cows with a 3.00 body condition score (BCS) < 3.75 after treatment and loose-housed cows were more likely to become pregnant. Treatment during winter showed higher pregnancy success than that in the summer and rainy seasons. The cost-efficiency analysis showed that the TAI protocol was the most cost-efficient option for noncyclic cows, whereas the EAI protocol was the most cost-efficient option for cyclic cows.

Salmonellosis is one of the leading causes of gastrointestinal infections in humans. In Canada, it is estimated that approximately 87,500 cases of salmonellosis occur every year in humans, resulting in 17 deaths. In the United States, it is estimated that 26,500 hospitalizations and 420 deaths occur every year. In dairy cattle, infections caused by nontyphoidal Salmonella enterica can cause mild to severe disease, including enteritis, pneumonia, and septicemia. Our study objectives were to determine the proportion of fecal samples positive for Salmonella in dairy cattle in Canada and determine the resistance pattern of these isolates. We used data collected through the Canadian Dairy Network for Antimicrobial Stewardship and Resistance (CaDNetASR). Pooled fecal samples from pre-weaned calves, post-weaned heifers, lactating cows, and manure storage were cultured for Salmonella, and the isolates were identified using matrix-assisted laser desorption/ionization-time of flight mass spectrometry. Antimicrobial susceptibilities were determined using the minimum inhibitory concentration test, and resistance interpretation was made according to the Clinical and Laboratory Standards Institute. A 2-level, multivariable logistic regression model was built to determine the probability of recovering Salmonella from a sample while accounting for province, year, and sample source. The proportion of farms with at least one positive sample were 12% (17/140), 19% (28/144), and 17% (24/144) for the sampling years 2019, 2020, and 2021, respectively. Out of the 113 Salmonella isolates, 23 different serovars were identified. The occurrence of Salmonella appeared to be clustered by farms and provinces. The most common serovars identified were Infantis (14%) and Typhimurium (14%). Overall, 21% (24/113) of the Salmonella isolates were resistant to at least one antimicrobial. Resistance to tetracycline was commonly observed (17%); however, very limited resistance to category I antimicrobials (categorization according to Health Canada that includes third-generation cephalosporins, fluoroquinolones, polymyxins, and carbapenems) was observed, with one isolate resistant to amoxicillin/clavulanic acid. The proportion of Salmonella isolates resistant to 2 and 3 antimicrobial classes was 3.5% and 8.8%, respectively. Our study provided valuable information on the proportion of fecal samples positive for Salmonella, the serovars identified, and associated resistance patterns across CaDNetASR herds, at regional and national levels.

As clinical mastitis (CM) treatments are responsible for a large portion of antimicrobial use on dairy farms, many selective CM treatment protocols have been developed and evaluated against a blanket treatment approach of CM cases. Selective treatment protocols use outcomes of diagnostic tests to exclude CM cases from antimicrobial treatment when they are unlikely to benefit. To tailor interventions to increase uptake of selective treatment strategies, a comprehension of current on-farm treatment practices and factors affecting treatment decisions is vital. Two questionnaires were conducted among 142 farms across 5 provinces participating in the Canadian Dairy Network for Antimicrobial Stewardship and Resistance in this cross-sectional study. Self-reported adoption of selective CM treatments by dairy farmers was 64%, with median of 82% of cows treated in those herds using selective treatment. Using logistic regression models, the odds to implement a selective CM treatment protocol increased with a decreasing average cow somatic cell count. No other associations were identified between use of a selective CM treatment protocol and farm characteristics (herd size, CM incidence, province, milking system, and housing system). Three subsets of farmers making cow-level CM treatment decisions were identified using a cluster analysis approach: those who based decisions almost exclusively on severity of clinical signs, those who used various udder health indicators, and farmers who also incorporated more general cow information such as production, age, and genetics. When somatic cell count was considered, the median threshold used for treating was >300,000 cells/mL at the last Dairy Herd Improvement test. Various thresholds were present among those considering CM case history. Veterinary laboratories were most frequently used for bacteriological testing. Test results were used to start, change, and stop treatments. Regardless of protocol, reasons for antimicrobial treatment withheld included cow being on a cull list, having a chronic intramammary infection, or being at end of lactation (i.e., close to dry off). If clinical signs persisted after treatment, farmers indicated that they would ask veterinarians for advice, stop treatment, or continue with the same or different antibiotics. Results of this study can be used to design interventions targeting judicious mastitis-related antimicrobial use, and aid discussions between veterinarians and dairy producers regarding CM-related antimicrobial use.

The objective of this cross-sectional study was to determine associations between calf management practices, the number of antimicrobial treatments, and antimicrobial resistance in pre-weaned heifers on Canadian dairy farms. A composite of 5 fecal samples from pre-weaned calves was collected from 142 dairy farms in 5 provinces and analyzed for phenotypic antimicrobial susceptibility with the microbroth dilution method. Questionnaires were used to capture herd characteristics and calf management practices used on the farm. Calf treatment records were collected during the farm visits. Escherichia coli was isolated from all 142 fecal samples with the highest resistance to tetracycline (41%), followed by sulfisoxazole (36%), streptomycin (32%), chloramphenicol (28%), ampicillin (16%), trimethoprim-sulfamethoxazole (15%), ceftriaxone (4.2%), cefoxitin (2.8%), amoxicillin-clavulanic acid (2.1%), ciprofloxacin (2.1%), nalidixic acid (2.1%), azithromycin (1.4%), and gentamicin (1.4%). Multidrug resistance was observed in 37% of E. coli isolates. Three-quarters of farms used fresh colostrum as the most common type of colostrum fed to calves. Colostrum quality was checked on 49% of farms, but the transfer of passive immunity was only checked on 32% of farms in the last 12 mo. Almost 70% of farms used straw or hay or a combination as the bedding material for calves. Among the 142 farms, a complete set of calf records were collected from 71 farms. In a multivariable logistic regression model, farms with ≥1.99 – 32.57 antimicrobial treatments/calf-year were 3.2 times more likely to have multidrug resistant E. coli in calf feces compared farms with <1.99 antimicrobial treatments/calf-year. Farms using hay or straw beddings were 5.1 times less likely to have multidrug resistant E. coli compared with those with other bedding materials including shavings or sawdust. Bedding management practices on farms may need to be investigated to reduce the potential impact on disseminating multidrug resistant bacteria.

Teat sealants (TSs) consist of sterile formulations with no antibacterial activity. Alone or in combination with antimicrobial (AM) or non-AM treatments, TSs have been commonly used in dairy cows at dry-off to prevent intra-mammary infections (IMIs) during the dry period. This study aimed to identify and synthesise the available evidence on the efficacy of combining TSs with AM treatments on the incidence and prevalence of IMIs. A comprehensive search of three electronic databases, two relevant conference proceedings, and reference lists of reviews and eligible articles was conducted to retrieve and identify studies that could answer the following question: in dairy cows, how does the efficacy of an AM–TS combination administered at dry-off compare with an AM alone for preventing new IMI? In addition to the general IMIs, bacterial species-specific data were extracted and combined into nine distinct pathogen groups: coagulase-positive and negative staphylococci; S. dysgalactiae; non-dysgalactiae Streptococci; E. coli; non-E. coli Enterobacteriaceae; Corynebacterium spp.; yeast and other frequent mastitis pathogens. The structural relationship between each study's prevalence and incidence, as the new (incidence) and persistent (uncured) infections make up the prevalence, was utilised to approximate a variance-covariance matrix for the within-study correlation between their study-specific log odds ratios (ORs). A bivariate random-effects meta-analysis was employed, utilising the within- and between-study correlations to synthesise both outcomes simultaneously. The risk of bias was assessed using the Cochrane ROBINS-I tool, and the quality of the body of evidence was rated using the GRADE approach. A total of 17 trials (16 studies), providing either IMIs incidence (n = 4), prevalence (n = 3) or both (n = 10), were identified. Overall, quarters infused with AM-TS combinations showed lower odds of new IMIs post-calving (OR=0.70; 95% CI=0.57–0.86; Wald test P < 0.001) than those which received only AMs. Across the pathogen groups, varying levels of reduction of new IMIs were found, where administration of TSs was most effective against S. dysgalactiae (OR=0.47; 95% CI=0.23–0.98), non-dysgalactiae streptococci (OR=0.60; 95% CI=0.49–0.74), E. coli (OR=0.62; 95% CI=0.50–0.77), Corynebacterium spp. (OR=0.68; 95% CI=0.52–0.90) and coagulase-negative staphylococci (OR=0.85; 95% CI=0.76–0.94). However, additional TS infusion did not significantly reduce new IMIs in the remaining pathogen groups. The current meta-analytic evidence supports the efficacy of using TS add-on infusions in dairy cows at dry-off for reducing the incidence and prevalence of IMIs post-calving; however, pathogen group differences should be considered.

Infections with antimicrobial resistant pathogens are a major threat to human and animal health worldwide. Further, reduction of livestock-associated antimicrobial use (AMU) is often identified as an area of focus. Selective dry cow therapy (DCT) warrants consideration as an important way to decrease AMU on Canadian dairy farms. In addition, teat sealants (TS) are a nonantimicrobial alternative for prevention of intramammary infection during the dry period. Therefore, objectives of this study were to determine how antimicrobials and TS are used at dry-off on Canadian dairy farms to determine selective DCT uptake and enacted selection protocols. It was expected that these data will provide a baseline understanding of DCT practices and highlight areas for future intervention to further reduce AMU. An observational study was conducted utilizing 2 in-person questionnaires conducted between July 2019 and September 2021 on 144 participating dairy farms in 5 Canadian provinces (British Columbia = 30, Alberta = 30, Ontario = 31, Québec = 29, and Nova Scotia = 24). Overall, 45 farms (31%) reported adopting selective DCT, 95 (66%) enacted blanket DCT, and 4 (3%) did not provide antimicrobial DCT. Farms enacting selective DCT had approximately 50% less intramammary antimicrobials used at dry-off compared with blanket DCT farms. Cow somatic cell count history was the most common criterion for selective DCT decision-making, followed by previous clinical mastitis history, bacteriological culture, and milk production. A slight majority of farms (56%) applied TS to all cows at dry-off, whereas 17 farms (12%) used TS selectively, and 46 farms (32%) did not use TS. Larger herds more often used TS, and farms with an automatic milking system more often used TS selectively than applied to all cows. Results highlighted the variability in antimicrobial treatment and TS use protocols at dry-off on Canadian dairy farms, and the potential for further antimicrobial reduction with increased adoption of selective DCT.

Antimicrobial resistance in pathogenic bacteria is one of the preeminent concerns for the future of global health. There is a dose-dependent relationship between antimicrobial use (AMU) and the prevalence of antimicrobial-resistant pathogens. As most AMU in Canada is related to animal agriculture, there is a need to reduce overall AMU, which could be accomplished through surveillance of AMU in animal agriculture, including the dairy industry. The objective of this study was to quantify AMU on dairy farms across Canada. This study had two parts: a description of data collected in 2019–2020, and a meta-analysis comparing this data to previous estimates of AMU in the Canadian dairy industry. The first included a garbage can audit (GCA) on 107 farms in four Canadian provinces (British Columbia, Alberta, Ontario, and Nova Scotia) in 2020; AMU data were converted to the dose-based metrics of defined course doses (DCD) and defined daily doses (DDD). Mixed-effect linear models were fit to determine the relationship between province and use of different classes of antimicrobials. On average, for every 100 animals on the farm, 117 DCD of antimicrobials were administered per year (IQR: 55, 158). These treatments amounted to 623 DDD / 100 animal-yr (IQR: 302, 677 DDD/100 animal-years). Penicillins were the most used class of antimicrobials, followed by first-and third-generation cephalosporins. Farms in Ontario used more third-generation cephalosporins than other provinces. The second part of this study compared AMU in 2020 to previously reported Canadian studies through a meta-analysis. A GCA was conducted in 2007–2008 in Alberta, Ontario, Québec, and the Maritime provinces (Prince Edward Island, New Brunswick and Nova Scotia); another GCA was conducted in Québec in 2018. Overall, AMU was lower in 2018–2020 than in 2007–2008, with the exception of third-generation cephalosporin use, which increased.

Supplementing growing cattle grazing native subtropical Campos grasslands during winter improves the low, even negative, average daily weight gain (ADG) typical of extensive animal production systems in Uruguay. Nonetheless, to render the practice profitable, it is crucial to control supplement feed efficiency (SFE), that is, the difference in ADG between supplemented and control animals (ADGchng) per unit of supplement dry matter (DM) intake. Little has been studied specifically on how SFE varies in these systems. The objective of this study was to quantify the magnitude and variation in SFE of growing beef cattle grazing stockpiled native Campos grasslands during winter and assess putative associations with herbage, animals, supplements, and climatic variables. We compiled data from supplementation trials carried out in Uruguay between 1993 and 2018, each evaluating between one and six supplementation treatments. The average ADG of unsupplemented and supplemented animals were 0.13 +/- 0.174 and 0.49 +/- 0.220 kg/animal/day, respectively. In both cases, ADG decreased linearly as the proportion of green herbage in the grazed grassland was lower, but the ADG of unsupplemented animals was further reduced when winter frosts were numerous. Estimated SFE were moderately high, with an average of 0.21 +/- 0.076 ADGchng/kg DM, resulting from average ADGchng of 0.38 +/- 0.180 kg/animal/day in response to an average supplementation rate of 1.84 +/- 0.68 kg supplement DM intake/animal/day (0.86% +/- 0.27% body weight). No association was found between SFE and supplementation rate or type (protein vs. energy-based; P > 0.05), but forage allowance negatively affected it, and herbage mass positively affected it, yet in a smaller magnitude, suggesting that a balance is needed between the two to maximize SFE. Weather conditions during trials affected SFE (P < 0.05), with greater SFE in winters with lower temperatures and more frosts. Daytime grazing time was consistently lower in supplemented animals compared to their unsupplemented counterparts, whereas ruminating time during the day was similar, increasing as the proportion of green herbage decreased. Herbage intake estimated from energy balance suggested the existence of some substitution effect. This agrees with the moderately high SFE and with the total digestible nutrients-to-protein ratio of these subtropical humid grasslands being higher than in semi-arid rangelands and dry-season tropical pastures but lower than in sown pastures. LAY SUMMARY Beef cattle are reared on native grasslands worldwide. In the native Campos-the subtropical humid grasslands part of the Pampa biome in southern South America-animals often lose weight during winter due to insufficient quantity or quality of available forage. Therefore, supplementation with concentrates is advocated. Notwithstanding its productive impact, this practice is unprofitable when supplement feed efficiency (SFE) is low. We collated data from 25 trials carried out from 1993 to 2018 in Uruguay to better understand how and why SFE varies in growing cattle grazing stockpiled Campos. On average, animals gained 0.21 kg of body weight per kg of consumed supplement, but variation was large. Winters with more frosts resulted in greater responses, rendering the practice more efficient. The amount of forage per animal negatively affected efficiency, while overall forage availability positively affected it (yet in a smaller magnitude), suggesting that in order to be more efficient, a balance between them is needed. Protein concentration of supplements was associated with SFE. Nonetheless, the proportion of green biomass in offered herbage did correlate with weight gain and grazing behavior of the cattle. The total digestible nutrients-to-protein ratio of Campos winter herbage-halfway between that of rangelands and sown pastures-would explain the observed relatively high SFE.

Previous studies on winter supplementation of growing cattle grazing stockpiled native Campos grasslands suggest that forage allowance (FA), herbage mass, and weather conditions before and during the supplementation period could all affect supplement feed efficiency (SFE)—that is, the difference or change in average daily gain (ADG) between supplemented (S) and control (C) animals (ADGchng, kg) per unit (kg) of supplement dry matter (DM) intake. In this study, we analyse data from fifteen collated winter supplementation trials carried out in Uruguay between 2004 and 2018. The working hypotheses of this research paper were: (i) that average substitution rates are positive, and (ii) that ADGchng is not constant throughout the supplementation period and that its variation may be attributed to sward, animal or weather variables. There were two main objectives: (i) to estimate the average supplement substitution rate (sSbR, kg forage, f, dry matter, DM intake reduction: kg supplement DM intake) and potential herbage intake substitution rate (hSbR, kg fDM intake reduction: kg fDM intake of control animals), and its association with SFE, and, (ii) to assess the existence of different phases and supplementation response patterns and its association with other relevant variables. Estimated substitution rates were always positive (sSbR = 0.3–1.1 kg/kg; hSbR = 0.1–0.3 kg/kg) and were negatively and moderately associated with SFE. Supplementation proved to be a dynamic process where three possible supplementation responses over the supplementation period were identified (linear, quadratic and Weibull). While linear patterns did not appear distinctly associated with any particular set of variables, quadratic models were mostly associated with herbage biomass and substitution rates, whereas Weibull models were the clearest in their association with frosts. Regardless of the response pattern, at the beginning of the trials it was the animals’ body weight and supplement quality that most influenced supplement response, whereas towards the end, supplementation intake, supplemented animals’ ADG and forage quality played a more relevant role. The estimated parameters and response patterns are expected to be used as inputs in decision support systems for livestock farmers in the future.

Antimicrobial resistance (AMR) in animals, including dairy cattle, is a significant concern for animal and public health worldwide. In this study, we used data collected through the Canadian Dairy Network for Antimicrobial Stewardship and Resistance (CaDNetASR) to: (1) describe the proportions of AMR in fecal E. coli, and (2) investigate the relationship between antimicrobial use (AMU) (intramammary and systemic routes, while ac-counting for confounding by other variables) and AMR/multidrug resistance (MDR - resistance to & GE; 3 antimi-crobial classes) in fecal E. coli from Canadian dairy farms. We hypothesized that an increase of the AMU was associated with an increase in AMR in E. coli isolates. A total of 140 dairy farms across five provinces in Canada were included in the study. Fecal samples from pre-weaned calves, post-weaned heifers, lactating cows, and farm manure storage were cultured, and E. coli isolates were identified using MALDI-TOF MS. The minimum inhibitory concentrations (MIC) to 14 antimicrobials were evaluated using a microbroth dilution methodology. AMU was quantified in Defined Course Dose (DCD -the dose for a standardized complete treatment course on a standard size animal) and converted to a rate indicator -DCD/100 animal-years. Of 1134 fecal samples collected, the proportion of samples positive for E. coli in 2019 and 2020 was 97.1% (544/560) and 94.4% (542/574), respectively. Overall, 24.5% (266/1086) of the E. coli isolates were resistant to at least one antimicrobial. Resistance towards tetracycline was commonly observed (20.7%), whereas resistance to third-generation cephalosporins, fluoroquinolones, and carbapenems was found in 2.2%, 1.4%, and 0.1% of E. coli isolates, respectively. E. coli isolates resistant to two or & GE; 3 antimicrobial classes (MDR) was 2.7% and 15%, respectively. Two multilevel models were built to explore risk factors associated with AMR with AMU being the main exposure. Systemic AMU was associated with increased E. coli resistance. For an increase in systemic AMU equivalent to its IQR, the odds of resistance to any antimicrobial in the model increased by 18%. Fecal samples from calves had higher odds of being resistant to any antimicrobial when compared to other production ages and farm manure storage. The samples collected in 2020 were less likely to be resistant when compared to samples collected in 2019. Compared to previous studies in dairy cattle in North America, AMR in E. coli was lower.