Isolation and Characterization of Contemporary Bovine Coronavirus Strains.

Bovine coronavirus (BCoV) poses a threat to cattle health worldwide, contributing to both respiratory and enteric diseases. However, few contemporary strains have been isolated. In this study, 71 samples (10 nasal and 61 fecal) were collected from one farm in Ohio in 2021 and three farms in Georgia in 2023. They were screened by BCoV-specific real-time reverse transcription-PCR, and 15 BCoV-positive samples were identified. Among them, five BCoV strains from fecal samples were isolated using human rectal tumor-18 (HRT-18) cells. The genomic sequences of five strains were obtained. The phylogenetic analysis illustrated that these new strains clustered with US BCoVs that have been detected since the 1990s. Sequence analyses of the spike proteins of four pairs of BCoVs, with each pair originally collected from the respiratory and enteric sites of one animal, revealed the potential amino acid residue patterns, such as D1180 for all four enteric BCoVs and G1180 for three of four respiratory BCoVs. This project provides new BCoV isolates and sequences and underscores the genetic diversity of BcoVs, the unknown mechanisms of disease types, and the necessity of sustained surveillance and research for BCoVs.

A survey of antimicrobial use practices on veal farms in the United States.

Neonatal veal calves are highly susceptible to bacterial diseases. Occasional sub-optimal early-life care and long-distance transportation result in high disease burden and antimicrobial treatment incidence. Nonetheless, judicious use of antimicrobials is necessary to mitigate the animal and human health impacts of antimicrobial resistance. The objective of this cross-sectional study was to use a clinical vignette-based survey approach to evaluate the potential for reduced group or individual therapeutic antimicrobial use. The survey included items probing the adherence to veterinary-written protocols, antimicrobial use (AMU) at the calf- and group-level, and the treatment actions to case vignettes of calf diarrhoea, pneumonia, and navel infection. The survey was mailed to all veal calf producers within two U.S. production companies (n = 32 producers in Company 1; n = 70 producers in Company 2) in February and December 2019, respectively. The overall survey response rate was 36% (21/59). Although 95% of producers reported having veterinary-written treatment protocols for diarrhoea, pneumonia, and navel infection, veal producers infrequently (<50% of the time) referenced these protocols. Veal producers were primarily trained for disease identification and treatment by observing other personnel "on-the-job" (81%). Veal producers reported a high incidence of calf diarrhoea relative to pneumonia and naval infection, a lower percentage (≤40%) of diarrhoea cases being treated individually with antimicrobials. Using clinical vignettes, our results suggest that AMU decisions among veal producers depend on the severity of clinical signs for diarrhoea and pneumonia, while navel infections are often treated with antimicrobials regardless of sign severity. Nearly two-thirds of veal producers reported treating uncomplicated cases of diarrhoea (watery stool with normal body temperature, activity, and appetite), more than previously reported from dairy producers (37.1%). Findings from this survey suggest that calf producer-focused training to guide antimicrobial treatment decisions and improve producer adherence to veterinary-written treatment protocols may have important impacts on judicious antimicrobial use.

Antimicrobial Use and Resistance in Surplus Dairy Calf Production Systems.

Surplus calves, which consist predominately of male calves born on dairy farms, are an underrecognized source of antimicrobial-resistant (AMR) pathogens. Current production systems for surplus calves have important risk factors for the dissemination of pathogens, including the high degree of commingling during auction and transportation and sometimes inadequate care early in life. These circumstances contribute to an increased risk of respiratory and other infectious diseases, resulting in higher antimicrobial use (AMU) and the development of AMR. Several studies have shown that surplus calves harbor AMR genes and pathogens that are resistant to critically important antimicrobials. This is a potential concern as the resistant pathogens and genes can be shared between animal, human and environmental microbiomes. Although knowledge of AMU and AMR has grown substantially in dairy and beef cattle systems, comparable studies in surplus calves have been mostly neglected in North America. Therefore, the overall goal of this narrative review is to summarize the existing literature regarding AMU and AMR in surplus dairy calf production, highlight the management practices contributing to the increased AMU and the resulting AMR, and discuss potential strategies and barriers for improved antimicrobial stewardship in surplus calf production systems.

Prevalence and Sources of Salmonella Lymph Node Infection in Special-Fed Veal Calves.

ABSTRACT: Peripheral lymph nodes (LNs) have been implicated as potential contaminants of ground beef, yet the source and timing of Salmonella LN infection in cattle is still unclear, limiting targeted intervention. The aim of this study was to leverage the vertical integration of special-fed veal production to identify preharvest environmental exposures, specifically in livestock trailers and harvest facility holding pens where calves spend 30 min to 4 h, that result in Salmonella LN infection. Ten cohorts of 80 to 82 veal calves were followed through the harvest process, and environmental samples were collected in barns, trailers, and holding pens. Mesenteric LNs from 35 calves were collected at harvest, and 25 prefemoral LNs per cohort were pooled. Within the same cohort, for 12 samples for which the serovar of the environmental and calf LN Salmonella isolates matched, the isolates were submitted for whole genome sequencing to determine whether environmental exposure resulted in LN infection. Cohort-level Salmonella mesenteric LN prevalence ranged from 0% (0 of 35 samples) to 80% (28 of 35 samples), and pooled prefemoral LNs were positive for Salmonella in 3 of the 10 cohorts. Salmonella prevalence in samples from barns, livestock trailers, and harvest facility holding pens was 22% (13 of 60 samples), 74% (59 of 80 samples), and 93% (74 of 80 samples), respectively. Some environmental and LN isolates were multidrug resistant. Four instances of Salmonella transmission from trailers and/or holding pens to calf LNs were supported by sequence data. Salmonella serovars Agona, Give, and Muenster were identified in transmission events. One instance of transmission from the livestock trailer, two instances from holding pens, and one instance from either trailer or holding pens were observed. Further research is needed to evaluate the extent of environmental Salmonella transmission in cattle and to determine whether targeted interventions in trailers or holding pens could reduce novel Salmonella LN infection in veal calves before harvest.

A focus group study of Ontario dairy producer perspectives on neonatal care of male and female calves.

Providing optimal calf care remains a challenge on many dairy farms and has important implications for the future health, welfare, and productivity of male and female calves. Recent research suggests that male dairy calves receive a lower quality of care early in life than female calves, but further investigation is required to determine the factors that influence this disparity. The objectives of this study were to understand dairy producer perspectives on neonatal calf care practices and explore differences between male and female calf care. Overall, 23 dairy producers in Ontario, Canada, participated in 4 focus groups about calf care practices that were recorded and evaluated qualitatively using thematic analysis. Major barriers for good calf care included lack of knowledge about the best management practices for calf care and the prioritization of farm resources toward the milking herd. Some producers also noted that farm infrastructure (particularly during challenging weather) and employee training were important limitations. The economic cost of providing good neonatal calf care was important primarily for male calves and acted as a motivation or a barrier depending on the producer's beliefs about calf care and how they chose to market their calves. The primary source of knowledge producers used to develop calf care practices was their own experience, although many also relied on dairy-industry advisors, most often veterinarians. Producers were motivated by social norms, along with intrinsic pride and obligation to provide good calf care, and these motives were influenced by their emotional state. Producers expressed beliefs about which aspects of calf care are most important-notably colostrum management-and appreciated simple and economical solutions to calf-rearing challenges. Calf care practices were varied, and we identified a diversity of knowledge, motivations, and barriers to adopting best management practices, which sometimes differed between male and female calves. Some producers said that they did not know what happened to their male calves after they left the farm and tended to prioritize the care of female over male calves in subtle ways, such as less timely provision of colostrum. The infrastructure investment and other costs associated with caring for male calves often limited their care, but producers were still motivated to provide adequate care for male calves. These findings represent potential targets for additional research and intervention strategies to improve calf care practices on dairy farms.