Economic effects of bovine respiratory disease on feedlot cattle during backgrounding and finishing phases1

Comprehensive time-course gene expression evaluation of high-risk beef cattle to establish immunological characteristics associated with undifferentiated bovine respiratory disease

Bovine respiratory disease (BRD) remains the leading infectious disease in beef cattle production systems. Host gene expression upon facility arrival may indicate risk of BRD development and severity. However, a time-course approach would better define how BRD development influences immunological and inflammatory responses after disease occurrences. Here, we evaluated whole blood transcriptomes of high-risk beef cattle at three time points to elucidate BRD-associated host response. Sequenced jugular whole blood mRNA from 36 cattle (2015: n = 9; 2017: n = 27) across three time points (n = 100 samples; days [D]0, D28, and D63) were processed through ARS-UCD1.2 reference-guided assembly (HISAT2/Stringtie2). Samples were categorized into BRD-severity cohorts (Healthy, n = 14; Treated 1, n = 11; Treated 2+, n = 11) via frequency of antimicrobial clinical treatment. Assessment of gene expression patterns over time within each BRD cohort was modeled through an autoregressive hidden Markov model (EBSeq-HMM; posterior probability ≥ 0.5, FDR < 0.01). Mixed-effects negative binomial models (glmmSeq; FDR < 0.05) and edgeR (FDR < 0.10) identified differentially expressed genes between and across cohorts overtime. A total of 2,580, 2,216, and 2,381 genes were dynamically expressed across time in Healthy, Treated 1, and Treated 2+ cattle, respectively. Genes involved in the production of specialized resolving mediators (SPMs) decreased at D28 and then increased by D63 across all three cohorts. Accordingly, SPM production and alternative complement were differentially expressed between Healthy and Treated 2+ at D0, but not statistically different between the three groups by D63. Magnitude, but not directionality, of gene expression related to SPM production, alternative complement, and innate immune response signified Healthy and Treated 2+ cattle. Differences in gene expression at D63 across the three groups were related to oxygen binding and carrier activity, natural killer cell-mediated cytotoxicity, cathelicidin production, and neutrophil degranulation, possibly indicating prolonged airway pathology and inflammation weeks after clinical treatment for BRD. These findings indicate genomic mechanisms indicative of BRD development and severity over time.

Determining the Economically Optimum Metaphylactic Strategy for Cattle Cohorts of Varied Demographic Characteristics

Metaphylactic antibiotic use in feeder cattle is a common practice to control respiratory disease. Antimicrobial stewardship is important to ensure continued efficacy and to protect animal welfare. The objective of this study is to identify characteristics of cohorts of cattle that had not received metaphylaxis that would have benefited economically from the use of metaphylaxis. Cohorts (n = 12,785; 2,206,338 head) from 13 feedlots that did not receive metaphylaxis were modeled using an economic model to estimate net returns for three metaphylactic options. Logistic regression models with covariates for entry weight, sex, average daily weight gain, number of animals per cohort, and days on feed, with feedlot as a random effect, were used to determine the model-adjusted probability of cohorts benefiting economically from metaphylaxis. Most (72%) cohorts in this data set that had not received metaphylaxis at arrival would not economically benefit from metaphylaxis. Sex, entry weight category, number of cattle in the cohort, and average daily weight gain were associated with the likelihood of benefitting economically from metaphylaxis. The results illustrated that cattle cohort demographics influenced the probability that cohorts would benefit economically from metaphylaxis and the type of metaphylaxis utilized, and integrating this information has the potential to influence the metaphylaxis decision.

Effect of bovine respiratory disease on the respiratory microbiome: a meta-analysis

Background

Bovine respiratory disease (BRD) is the most devastating disease affecting beef and dairy cattle producers in North America. An emerging area of interest is the respiratory microbiome's relationship with BRD. However, results regarding the effect of BRD on respiratory microbiome diversity are conflicting.

Results

To examine the effect of BRD on the alpha diversity of the respiratory microbiome, a meta-analysis analyzing the relationship between the standardized mean difference (SMD) of three alpha diversity metrics (Shannon's Diversity Index (Shannon), Chao1, and Observed features (OTUs, ASVs, species, and reads) and BRD was conducted. Our multi-level model found no difference in Chao1 and Observed features SMDs between calves with BRD and controls. The Shannon SMD was significantly greater in controls compared to that in calves with BRD. Furthermore, we re-analyzed 16S amplicon sequencing data from four previously published datasets to investigate BRD's effect on individual taxa abundances. Additionally, based on Bray Curtis and Jaccard distances, health status, sampling location, and dataset were all significant sources of variation. Using a consensus approach based on RandomForest, DESeq2, and ANCOM-BC2, we identified three differentially abundant amplicon sequence variants (ASVs) within the nasal cavity, ASV5_Mycoplasma, ASV19_Corynebacterium, and ASV37_Ruminococcaceae. However, no ASVs were differentially abundant in the other sampling locations. Moreover, based on SECOM analysis, ASV37_Ruminococcaceae had a negative relationship with ASV1_Mycoplasma_hyorhinis, ASV5_Mycoplasma, and ASV4_Mannheimia. ASV19_Corynebacterium had negative relationships with ASV1_Mycoplasma_hyorhinis, ASV4_Mannheimia, ASV54_Mycoplasma, ASV7_Mycoplasma, and ASV8_Pasteurella.

Conclusions

Our results confirm a relationship between bovine respiratory disease and respiratory microbiome diversity and composition, which provide additional insight into microbial community dynamics during BRD development. Furthermore, as sampling location and sample processing (dataset) can also affect results, consideration should be taken when comparing results across studies.

Determining Frequency of Common Pulmonary Gross and Histopathological Findings in Feedyard Fatalities

Pulmonary disease is often associated with feedlot cattle mortality, and the most common syndromes include bronchopneumonia, acute interstitial pneumonia, and bronchopneumonia with an interstitial pneumonia. The study objective was to utilize gross necropsy and histopathology to determine the frequency of pulmonary lesions from three major syndromes and agreement between gross and histopathological diagnosis. A cross sectional, observational study was performed at six U.S. feedyards using a full systematic necropsy to assess mortalities during summer 2022. A subset of mortalities had four lung samples submitted for histopathological diagnosis. Gross necropsy was performed on 417 mortalities, 402 received a gross diagnosis and 189 had a histopathological diagnosis. Descriptive statistics were used to evaluate pulmonary diagnosis frequency based on method (gross/histopathology), and generalized linear mixed models were used to evaluate agreement between histopathological and gross diagnoses. Using gross diagnosis, bronchopneumonia represented 36.6% of cases with acute interstitial pneumonia and bronchopneumonia with an interstitial pneumonia representing 10.0% and 35.8%, respectively. Results identified bronchopneumonia with an interstitial pneumonia as a frequent syndrome which has only been recently reported. Histopathological diagnosis had similar findings; bronchopneumonia represented 32.3% of cases, with acute interstitial pneumonia and bronchopneumonia with an interstitial pneumonia representing 12.2% and 36.0%, respectively. Histopathological diagnosis tended (p-VALUE = 0.06) to be associated with gross diagnosis. Pulmonary disease was common and both diagnostic modalities illustrated three primary syndromes: bronchopneumonia, acute interstitial pneumonia, and bronchopneumonia with an interstitial pneumonia with similar frequencies. Improved understanding of pulmonary pathology can be valuable for evaluating and adjusting therapeutic interventions.

Evaluation of First Treatment Timing, Fatal Disease Onset, and Days from First Treatment to Death Associated with Bovine Respiratory Disease in Feedlot Cattle

Bovine respiratory disease (BRD) is a frequent beef cattle syndrome. Improved understanding of the timing of BRD events, including subsequent deleterious outcomes, promotes efficient resource allocation. This study’s objective was to determine differences in timing distributions of initial BRD treatments (Tx1), days to death after initial treatment (DTD), and days after arrival to fatal disease onset (FDO). Individual animal records for the first BRD treatment (n = 301,721) or BRD mortality (n = 19,332) were received from 25 feed yards. A subset of data (318–363 kg; steers/heifers) was created and Wasserstein distances were used to compare temporal distributions of Tx1, FDO, and DTD across genders (steers/heifers) and the quarter of arrival. Disease frequency varied by quarter with the greatest Wasserstein distances observed between Q2 and Q3 and between Q2 and Q4. Cattle arriving in Q3 and Q4 had earlier Tx1 events than in Q2. Evaluating FDO and DTD revealed the greatest Wasserstein distance between cattle arriving in Q2 and Q4, with cattle arriving in Q2 having later events. Distributions of FDO varied by gender and quarter and typically had wide distributions with the largest 25–75% quartiles ranging from 20 to 80 days (heifers arriving in Q2). The DTD had right-skewed distributions with 25% of cases occurring by days 3–4 post-treatment. Results illustrate temporal disease and outcome patterns are largely right-skewed and may not be well represented by simple arithmetic means. Knowledge of typical temporal patterns allows cattle health managers to focus disease control efforts on the correct groups of cattle at the appropriate time.

Hematological and gene co-expression network analyses of high-risk beef cattle defines immunological mechanisms and biological complexes involved in bovine respiratory disease and weight gain

Bovine respiratory disease (BRD), the leading disease complex in beef cattle production systems, remains highly elusive regarding diagnostics and disease prediction. Previous research has employed cellular and molecular techniques to describe hematological and gene expression variation that coincides with BRD development. Here, we utilized weighted gene co-expression network analysis (WGCNA) to leverage total gene expression patterns from cattle at arrival and generate hematological and clinical trait associations to describe mechanisms that may predict BRD development. Gene expression counts of previously published RNA-Seq data from 23 cattle (2017; n = 11 Healthy, n = 12 BRD) were used to construct gene co-expression modules and correlation patterns with complete blood count (CBC) and clinical datasets. Modules were further evaluated for cross-populational preservation of expression with RNA-Seq data from 24 cattle in an independent population (2019; n = 12 Healthy, n = 12 BRD). Genes within well-preserved modules were subject to functional enrichment analysis for significant Gene Ontology terms and pathways. Genes which possessed high module membership and association with BRD development, regardless of module preservation (“hub genes”), were utilized for protein-protein physical interaction network and clustering analyses. Five well-preserved modules of co-expressed genes were identified. One module (“steelblue”), involved in alpha-beta T-cell complexes and Th2-type immunity, possessed significant correlation with increased erythrocytes, platelets, and BRD development. One module (“purple”), involved in mitochondrial metabolism and rRNA maturation, possessed significant correlation with increased eosinophils, fecal egg count per gram, and weight gain over time. Fifty-two interacting hub genes, stratified into 11 clusters, may possess transient function involved in BRD development not previously described in literature. This study identifies co-expressed genes and coordinated mechanisms associated with BRD, which necessitates further investigation in BRD-prediction research.

Predictive Models for Weekly Cattle Mortality after Arrival at a Feeding Location Using Records, Weather, and Transport Data at Time of Purchase

Feedlot mortality negatively affects animal welfare and profitability. To the best of our knowledge, there are no publications on predictive models for weekly all-cause mortality in feedlot cattle. In this study, random forest models to predict weekly mortality for cattle purchase groups (n = 14,217 purchase groups; 860,545 animals) from arrival at the feeding location (Day 1) to Day 42 and cumulative mortality from Day 43 until slaughter were built using records, weather, and transport data available at the time of purchase. Models were evaluated by calculating the root mean squared error (RMSE) and accuracy (as defined as the percent of purchase groups that had predictions within 0.25% and 0.50% of actual mortality). The models had high accuracy (>90%), but the RMSE estimates were high (range = 1.0% to 4.1%). The best predictors were maximum temperature and purchase weight, although this varied by week. The models performed well among purchase groups with low weekly mortality but performed poorly in high mortality purchase groups. Although high mortality purchase groups were not accurately predicted utilizing the models in this study, the models may potentially have utility as a screening tool for very low mortality purchase groups after arrival. Future studies should consider building iterative models that utilize the strongest predictors identified in this study.

Galyean Appreciation Club Review: Revisiting nutrition and health of newly received cattle - What have we learned in the last 15 years?

Our objective was to review the literature related to the health and management of newly received cattle published since a previous review by Duff and Galyean (2007). Bovine respiratory disease (BRD) continues to be a major challenge for the beef industry. Depending on disease severity, animals treated for BRD have decreased performance and lowered carcass value. Diagnosis of BRD is less effective than desired, and progress on developing real-time, chute-side methods to diagnose BRD has been limited. Systems that combine lung auscultation with temperature and BW data show promise. Assessment of blood metabolites and behavior monitoring offer potential for early identification of morbid animals. Vaccination and metaphylaxis continue to be important tools for prevention and control of BRD, but antimicrobial resistance is a concern with antibiotic use. Dietary energy concentration and roughage source/level continue to be important topics. Mineral supplementation has received considerable attention, particularly the use of organic vs. inorganic sources and injectable minerals or drenches given on arrival. Use of probiotics and prebiotics for newly received cattle has shown variable results, but further research is warranted. Health and nutrition of newly received cattle will continue to be an important research area in the years to come.

Prevalence of three Mycoplasma sp. by multiplex PCR in cattle with and without respiratory disease in central Mexico

This study aimed to identify Mycoplasma bovis, Myc. dispar, and Myc. bovirhinis, which are involved in bovine respiratory disease through a multiplex PCR as an alternative to culture's features that hamper Mycoplasma isolation. Nasal swabs were taken from 335 cattle with and without respiratory disease background (RDB) from dairy herds in the central region of Mexico. Each sample was divided in two; the first part was processed for the direct DNA extraction of the nasal swab and the second for Mycoplasma isolation, culture, and then the multiplex PCR was performed. In the nasal swabs, Myc. bovis was identified in 21.1%; Myc. dispar, in 11.8%; and Myc. bovirhinis, in 10.8% in cattle with RDB. Isolates were identified as Myc. bovis, 20.1%; Myc. dispar, 11.8%; and Myc. bovirhinis, 6.1%. There is a strong correlation between the presence of Mycoplasma identified by PCR and the clinical history of the disease (ρ < 0.0000). In animals without RDB, Myc. bovirhinis was the only species detected in 6.1% of the samples processed directly for multiplex PCR, and in 2% of the isolates. There is an excellent correlation (kappa 0.803) between the isolation and the 16S PCR and a high correlation (kappa 0.75) between the isolation and the multiplex PCR. Therefore, we conclude that the PCR multiplex test is highly sensitive and may be used for the diagnosis and surveillance of the three species in biological samples and mycoplasma isolates.

Multipopulational transcriptome analysis of post-weaned beef cattle at arrival further validates candidate biomarkers for predicting clinical bovine respiratory disease

Bovine respiratory disease (BRD) remains the leading infectious disease in post-weaned beef cattle. The objective of this investigation was to contrast the at-arrival blood transcriptomes from cattle derived from two distinct populations that developed BRD in the 28 days following arrival versus cattle that did not. Forty-eight blood samples from two populations were selected for mRNA sequencing based on even distribution of development (n = 24) or lack of (n = 24) clinical BRD within 28 days following arrival; cattle which developed BRD were further stratified into BRD severity cohorts based on frequency of antimicrobial treatment: treated once (treated_1) or treated twice or more and/or died (treated_2+). Sequenced reads (~ 50 M/sample, 150 bp paired-end) were aligned to the ARS-UCD1.2 bovine genome assembly. One hundred and thirty-two unique differentially expressed genes (DEGs) were identified between groups stratified by disease severity (healthy, n = 24; treated_1, n = 13; treated_2+, n = 11) with edgeR (FDR ≤ 0.05). Differentially expressed genes in treated_1 relative to both healthy and treated_2+ were predicted to increase neutrophil activation, cellular cornification/keratinization, and antimicrobial peptide production. Differentially expressed genes in treated_2+ relative to both healthy and treated_1 were predicted to increase alternative complement activation, decrease leukocyte activity, and increase nitric oxide production. Receiver operating characteristic (ROC) curves generated from expression data for six DEGs identified in our current and previous studies (MARCO, CFB, MCF2L, ALOX15, LOC100335828 (aka CD200R1), and SLC18A2) demonstrated good-to-excellent (AUC: 0.800–0.899; ≥ 0.900) predictability for classifying disease occurrence and severity. This investigation identifies candidate biomarkers and functional mechanisms in at arrival blood that predicted development and severity of BRD.

Assessment of bovine respiratory disease progression in calves challenged with bovine herpesvirus 1 and Mannheimia haemolytica using point-of-care and laboratory-based blood leukocyte differential assays

Blood leukocyte differentials can be useful for understanding changes associated with bovine respiratory disease (BRD) progression. By improving turnaround time, point-of-care leukocyte differential assays (PCLD) may provide logistical advantages to laboratory-based assays. Our objective was to assess BRD progression in steers challenged with bovine herpesvirus 1 and Mannheimia haemolytica using point-of-care and laboratory-based blood leukocyte differentials. Thirty Holstein steers (average body weight of 211 kg + 2.4 kg) were inoculated intranasally on day 0 with bovine herpesvirus 1 and intrabronchially on day 6 with Mannheimia haemolytica. Blood leukocytes differentials were measured using both assays from study days 0 to 13. Linear mixed models were fitted to evaluate the associations between: (1) the type of assay (laboratory-based or PCLD) with respect to leukocyte, lymphocyte, and neutrophil concentrations; (2) study day with cell concentrations; and (3) cell concentrations with lung consolidation measured at necropsy. Point-of-care leukocyte, lymphocyte, and neutrophil concentrations were significantly associated (P < 0.05) with the respective cell concentrations obtained from the laboratory-based leukocyte differential. Cell concentrations reported by both assays differed significantly (P < 0.05) over time, indicating shifts from healthy to viral and bacterial disease states. Lymphocyte concentrations, lymphocyte/neutrophil ratios obtained from both assays, and band neutrophil concentrations from the laboratory-based assay were significantly associated (P < 0.05) with lung consolidation, enhancing assessments of disease severity. The PCLD may be a useful alternative to assess BRD progression when laboratory-based leukocyte differentials are impractical.

Early prediction of respiratory disease in preweaning dairy calves using feeding and activity behaviors

Bovine respiratory disease (BRD) represents one of the major disease challenges affecting preweaning dairy-bred calves. Previous studies have shown that differences in feeding and activity behaviors exist between healthy and diseased calves affected by BRD. The aim of this study was to develop and assess the accuracy of models designed to predict BRD from feeding and activity behaviors. Feeding and activity behaviors were recorded for 100 male preweaning calves between ~8 to 42 d of age. Calves were group housed with ad libitum access to milk via automatic milk feeders, water, starter diet, and straw. Activity was monitored via a leg-mounted accelerometer. Health status of individual calves was monitored daily using an adapted version of the Wisconsin Scoring System to identify BRD. Three models were created to predict disease: (1) deviation from normal lying time based on moving averages (MA); (2) random forest (RF), a machine learning technique based on feeding and activity variables; and (3) a combination of RF and MA output. For the MA model, lying time was predicted based on behavior over previous days (3- and 7-d MA) and the expected value for the current day (based on calf age; measured using accelerometers). Data were not split into training and test data sets. Occasions when the actual lying time increased >9% of predicted lying time were classified as a deviation from normal and a disease alert was provided. Both feeding and activity behaviors were included within the RF model. Data were split into training (70%) and test (30%) data sets based on disease events. Events were classified as 2 d before, the day(s) of the disease event, and 2 d after the event. Accuracy of models was assessed using sensitivity, specificity, balanced accuracy, and Matthews correlation coefficient (MCC). If a positive disease prediction agreed with an actual disease event within a 3-d rolling window, it was classified as a true positive. Stand-alone models (RF; MA) showed high specificity (0.95; 0.97), moderate sensitivity (0.35; 0.43), balanced accuracy (0.65; 0.64), and MCC (0.25; 0.29). Combining outputs increased accuracy (specificity = 0.95, sensitivity = 0.54, balanced accuracy = 0.75, MCC = 0.36). The work presented is the first to demonstrate the use of modeling data derived from precision livestock farming techniques that monitor feeding and activity behaviors for early detection of BRD in preweaning calves, offering a significant advance in health management of youngstock.

A Retrospective, Observational Study on Antimicrobial Drug Use in Beef Fattening Operations in Northwestern Italy and Evaluation of Risk Factors Associated with Increased Antimicrobial Usage

Simple Summary

Antimicrobial usage in veterinary medicine is thought to be a source of antimicrobial resistance, with possible implications for human health. Certain antibiotics are considered critical for human health, and their use is being judiciously reduced in animal productions. The monitoring of antimicrobial consumption in animal production is key to lowering the risk of the development of antimicrobial resistance. With this study, we quantified antimicrobial usage in beef fattening operations in northwestern Italy before the implementation of a program intended to control antimicrobial usage in veterinary medicine. We found that antimicrobials defined as critical for human health (e.g., fluroquinolones) were often used also for metaphylactic treatment.

Abstract

The abuse or misuse of antimicrobials in animal production is thought to be a potential factor in the development of antimicrobial resistance in veterinary and human medicine. With this study, we wanted to quantify antimicrobial usage in beef fattening operations in northwestern Italy and to identify factors potentially influencing antimicrobial usage. The sample was composed of 26 beef fattening operations that import heifers and bulls from France. Data were extracted from the 2014 and 2015 treatment registers kept by the farmers. The mean (±SD) number of animal daily doses per animal (nADDa) per year for each farm was 3 (±2.1) during the study period (2014–2015). Group antimicrobial treatments (57.5% of all treatments) were often administered orally (70.5%) and consisted overwhelmingly of doxycycline (97%). Individual treatments (42.5% of all treatments) were administered parenterally (98.1%) and the most often used active substances were florfenicol (19.9%), marbofloxacin (19.5%), and tylosin (12.4%). There was a negative correlation between the nADDa for total and group treatments and average batch weight at arrival and between the amount of straw added per animal per day and the nADDa (p ≤ 0.05). Our data show that antimicrobials critical for human medicine were often used in beef fattening operations in northwestern Italy before the European guidelines for the prudent use of antimicrobials in veterinary medicine were issued. Additionally, the use of antimicrobials as a preventive group treatment was still widespread, mostly in lighter weight animals.

Economic impact of digital dermatitis, foot rot, and bovine respiratory disease in feedlot cattle

Digital dermatitis (DD) has emerged in North American feedlots, although production and economic impacts are not fully understood. Objectives of this study were to: (1) estimate the economic impact of a single case of DD, foot rot (FR), and bovine respiratory disease (BRD) in feedlot cattle and (2) determine its impact on average daily gain (ADG). Feedlot cattle health and production records were available from two feedlots for a 3-yr interval. The dataset consisted of 77,115 animal records, with 19.3% (14,900) diagnosed with a disease. Diseased animals were categorized into five groups: DD, FR, BRD, other diseases (OT), and two or more diseases (TM), with a treatment cumulative incidence of 6.0%, 59.1%, 10.7%, 12.7%, and 11.5%, respectively. FR was the disease with the highest cumulative incidence in both heifers and steers (58.8% and 59.6%, respectively). Of all fall-placed cattle diagnosed with any disease, 48.1% of the cases were FR. DD affected the partial budget in five out of the eight groups of cattle, with the highest impact of DD seen in grass yearling heifers and grass yearling steers: $-98 and $-96 CAD, respectively, relative to their healthier counterparts. Healthy cattle had a significantly higher ADG when compared with DD cattle in five of the eight categories, ranging from 0.11 kg/d in winter-placed heifers to 0.17 kg/d in fall-placed steers. In the economic analysis, it was concluded that on an individual animal basis, BRD was the most impactful of all analyzed diseases, whereas DD was second, marking the importance of controlling and mitigating this foot condition. Identifying differential effects of diseases on a partial budget analysis and ADG of the types of cattle stratified by sex enables feedlot producers to focus control and mitigation strategies on specific groups.

Impact of bovine respiratory disease in U.S. beef cattle

Bovine respiratory disease (BRD) is one of the most common and costly diseases of beef cattle. Much research has been conducted to understand prevention, treatment, and economic impacts of this syndrome. Impacts from BRD occur in multiple phases of the beef industry including both pre- and post-weaned calves. This disease causes negative impacts due to production losses, treatment costs, and cattle mortality. The large scope of BRD impacts merits further research on effective prevention and intervention technologies to limit deleterious impacts to the cattle industry.

Economic effects of policy options restricting antimicrobial use for high risk cattle placed in U.S. feedlots

The rising public health threat of antimicrobial resistance, the influence of food service companies, as well as the overall lack of positive image of using medical products in intensive farming are major drivers curbing antimicrobial use. In the future, government policies may affect practices of antimicrobial use in beef production in feedlots, a prominent current user of antimicrobials in animal agriculture, but also the agricultural industry generating the highest cash receipt in the U.S. Our objective was to estimate the cost effect from the following policies in feedlots: 1) using antimicrobials for disease prevention, control, and treatment; 2) using antimicrobials only for treatment of disease; and 3) not using antimicrobials for any reason. We modelled a typical U.S. feedlot, where high risk cattle may be afflicted by diseases requiring antimicrobial therapy, namely respiratory diseases, liver abscesses and lameness. We calculated the net revenue loss under each policy of antimicrobial use restriction. With moderate disease incidence, the median net revenue loss was $66 and $96 per animal entering the feedlot, for not using antimicrobials for disease prevention and control, or not using any antimicrobials, respectively, compared to using antimicrobials for disease prevention, control, and treatment. Losses arose mainly from an increase of fatality and morbidity rates, almost doubling for respiratory diseases in the case of antimicrobial use restrictions. In the case of antimicrobial use prohibition, decreasing the feeder cattle price by 9%, or alternatively, increasing the slaughter cattle price by 6.3%, would offset the net revenue losses for the feedlot operator. If no alternatives to antimicrobial therapy for prevention, control and treatment of current infectious diseases are implemented, policies that economically incentivize adoption of non-antimicrobial prevention and control strategies for infectious diseases would be necessary to maintain animal welfare and the profitability of beef production while simultaneously curbing antimicrobial use.

The Effect of Market Forces on Bovine Respiratory Disease

Bovine respiratory disease (BRD) is a persistent negative economic impact on beef and dairy industries and the inability to show any progress in controlling BRD is a source of increasing frustration among animal health professionals and the industry. The complex economic structure of the cattle industry leads to market failures in which cow-calf producers do not have sufficient economic incentive to invest in improved BRD control. This leads to higher costs for stocker and feedlot sectors. An industry-wide comprehensive effort is needed to coordinate and motivate enhanced BRD control focusing on producing healthy calves with less morbidity rather than treatment.

An evaluation of the economic effects of bovine respiratory disease on animal performance, carcass traits, and economic outcomes in feedlot cattle defined using four BRD diagnosis methods

Bovine respiratory disease (BRD) causes significant economic losses to the feedlot industry due to decreased production and increased costs associated with treatment. This study aimed to assess the impacts of BRD on performance, carcass traits, and economic outcomes defined using four BRD diagnosis methods: number of BRD treatments an animal received, pleural lesions at slaughter, lung lesions at slaughter, and clinical BRD status defined using both treatment records and lung and pleural lesions. Crossbred steers (n = 898), with an initial body weight of 432 kg (± SD 51), were followed from feedlot entry to slaughter. Veterinary treatment records were collected and lungs scored at slaughter for lesions indicative of BRD. There was an 18% morbidity rate and a 2.1% BRD mortality rate, with an average net loss of AUD$1,647.53 per BRD mortality. Animals treated ≥3 times for BRD had 39.6 kg lighter carcasses at slaughter and returned an average of AUD$384.97 less compared to animals never treated for BRD (P < 0.001). Animals with severe lung lesions at slaughter grew 0.3 kg/d less, had 14.3 kg lighter carcasses at slaughter, and returned AUD$91.50 less than animals with no lung lesions (P < 0.001). Animals with subclinical and clinical BRD had 16.0 kg and 24.1 kg lighter carcasses, respectively, and returned AUD$67.10 and AUD$213.90 less at slaughter, respectively, compared to healthy animals that were never treated with no lesions (P < 0.001). The severity of BRD based on the number of treatments an animal received and the severity of lung and pleural lesions reduced animal performance, carcass weight and quality, and economic returns. Subclinical BRD reduced animal performance and economic returns compared to healthy animals; however, subclinical animals still had greater performance than animals with clinical BRD. This information can be used to plan for strategic investments aimed at reducing the impacts of BRD in feedlot cattle such as improved detection methods for subclinical animals with lesions at slaughter and BRD treatment protocols.

Performance of multiple diagnostic methods in assessing the progression of bovine respiratory disease in calves challenged with infectious bovine rhinotracheitis virus and Mannheimia haemolytica1

The objective of this study was to evaluate the diagnostic performance of chute-side diagnostic methods for detecting physiological and pathological changes as indicators of early bovine respiratory disease (BRD) in calves experimentally inoculated with infectious bovine rhinotracheitis virus (IBR) and Mannheimia haemolytica (Mh). A challenge study was performed over 14 d in 30 Holstein steers [average weight (±SEM) = 211 kilograms (kg) ± 2.4 kg] inoculated on day 0 with IBR and on day 6 with Mh. Diagnostic methods included clinical illness scores (CIS), lung auscultation using a computer-aided stethoscope (CAS), rectal temperature, facial thermography, pulse oximetry, and bilateral thoracic ultrasonography. Animals were randomized into 1 of 5 necropsy days (days 6, 7, 9, 11, and 13) when the percentage of lung consolidation was estimated. The effect of study day on the results of the diagnostic methods and associations between each diagnostic method's values with lung consolidation measured at necropsy were determined with mixed models. Values for all diagnostic methods differed significantly (P < 0.01) by day. During the IBR phase (days 0 to 6) calves had "normal" to "moderate" CIS, whereas during the Mh phase (days 6.5 to 13) scores were predominantly "severe" to "moribund." Similarly, CAS scores were "normal" and "mild acute" during the IBR phase and "mild acute" to "moderate acute" after the Mh challenge. Oxygen saturation did not differ significantly between days 0, 1, 2, 4, and 6; however, significantly decreased 12 h after inoculation with Mh (P < 0.05). Mean lung consolidation between animal's right and left side recorded by ultrasound was 0.13% (±0.07) before the inoculation with Mh. However, during the Mh phase, mean consolidation increased significantly over time (P < 0.05). The percentage of lung consolidation at necropsy ranged from 1.7% (±0.82) on day 6 to 55.4% (±7.49) on day 10. Clinical illness scores, rectal temperature, facial thermography, oxygen saturation, and ultrasonography were significantly associated (P < 0.05) with lung consolidation at necropsy. In addition, there was a significant trend (P = 0.07) between CAS and lung consolidation scores at necropsy. These chute-side diagnostic methods are useful for detecting disease progression on animals with early stages of BRD.

Comparative evaluation of ultrasonography with clinical respiratory score in diagnosis and prognosis of respiratory diseases in weaned dairy buffalo and cattle calves

Background

Respiratory troubles have economic impacts in countries where livestock industry is an important segment of the agricultural sector, as well as these problems may cause significant economic losses for bovine producers. Various practical methods are used to assess diseases that affect the bovine respiratory system. Ultrasonography is a noninvasive tool that has been used frequently in diagnosis of various animal diseases. The present study was designed to establish whether thoracic ultrasonography is a diagnostic tool for detection of respiratory troubles in weaned buffalo and cattle calves, as well as to assess its prognostic value in comparison with clinical respiratory scores. Thirty five (15 buffalo and 20 cattle) calves were included. Twelve (6 buffalo and 6 cattle) clinically healthy calves were enrolled as controls.

Results

Based on physical examinations, clinical respiratory scores (CRS), ultrasound lung scores (ULS) and postmortem findings, animals were classified into 4 groups as pulmonary emphysema (n = 8), interstitial pulmonary syndrome (n = 7), bronchopneumonia (n = 12), and pleurisy (n = 8). The mean values of CRS and ULS were significantly higher in diseased calves (P < 0.01). In calves with pulmonary emphysema and interstitial syndrome, thoracic ultrasonography revealed numerous comet-tail artifacts, which varied in numbers and imaging features. Furthermore, variable degrees of pulmonary consolidation with alveolograms and bronchograms were noticed in bronchopneumonic calves. In addition, thick irregular or fragmented pleura with pleural effusions and fibrin shreds were imaged in calves with pleurisy. A weak correlation was calculated between CRS and ULS (r = 0.55, P < 0.01). Hematologically, the counts of white blood cells, activities of aspartate aminotransferase and partial tensions of carbon dioxide were significantly increased in all diseased groups. Serum concentrations of total globulins were higher in claves with bronchopneumonia (P < 0.05). The partial tension of oxygen was decreased in all diseased calves (P < 0.05).

Conclusions

Thoracic ultrasonography is a diagnostic tool for various lung troubles and assessment the grade and severity of pulmonary diseases, as well as it can be used as a follow-up tool for evaluating the prognosis of respiratory troubles and monitoring the efficacy of therapies.

Effect of suckler cow vaccination against glycoprotein E (gE)-negative bovine herpesvirus type 1 (BoHV-1) on passive immunity and physiological response to subsequent bovine respiratory disease vaccination of their progeny

The study objectives were: 1) to characterise the development of immunocompetence in beef suckler calves from birth to three months of age, and 2) to trace glycoprotein E (gE)-negative bovine herpesvirus type 1 (BoHV-1) antibodies from dam to calf and subsequent vaccination against pneumonia. Thirty multiparous beef suckler, spring-calving cows, consisting of two genotypes were involved; Limousin × Friesian (LF) and Charolais × Limousin (CL). Cows were immunised against the inactivated antigen strain of BoHV-1 (gE- (IBR marker vaccine) at day − 84 and received a booster at day − 56 relative to the expected calving date (d 0). Calves were immunised at 14 and 42 days of age against PI-3 virus, BRSV and Mannheimia (Pasteurella) haemolytica serotype A1 using a commercial vaccine administered subcutaneously. Additionally, calves were immunised against BoHV-1 at 42 days of age, using 1 dose of a live commercial vaccine administered intranasally. Blood samples were collected from all calves (n = 30) via jugular venipuncture at birth, prior to colostrum feeding (0 h), at 12 h (h), 24 h, 72 h and 168 h after the initial feeding of colostrum, and at d 7, 14, 28, 42, 56 and 84 post birth. The mean ratio of gE negative antibodies circulating in the blood of LF and CL dams pre-partum scored negative to gE ab (S/N ≥ 0.70). Antibody levels of BoHV-1 (wild type (wt)) peaked at 12 h post-birth in calves and declined thereafter, as the maternal antibodies decayed. There was no difference in BoHV-1 and BRSV antibody levels in calves post vaccination.

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Greater decrease in cow serum IgG concentration in LF cows than CL cows pre-partum.

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Progeny of LF cows have a greater pre-weaning ADG than the progeny of CL cows.

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Maternally derived antibodies affects response to vaccination in suckled beef calves.

Linking disease epidemiology and livestock productivity: The case of bovine respiratory disease in France

Concerns are growing over the impact of livestock farming on environment and public health. The livestock industry is faced with the double constraint of limiting its use of natural resources and antimicrobials while ensuring its economic sustainability. In this context, reliable methods are needed to evaluate the effect of the prevention of endemic animal diseases on the productivity of livestock production systems. In this study, an epidemiological and productivity model was used to link changes in Bovine Respiratory Disease (BRD) incidence with the productivity of the beef and dairy cattle sectors in France. Cattle production parameters significantly affected by BRD were selected through literature review. Previous field study results and national cattle performance estimates were used to infer growth performances, mortality rates and carcass quality in the cattle affected and not affected by BRD. A steady-state deterministic herd production model was used to predict the productivity of the dairy and beef sector and their defined compartments (breeding-fattening, feedlot young bulls, and feedlot veal) in case of BRD incidence reduction by 20%, 50% or 100%. Results suggested that BRD should be controlled at a priority in beef breeding farms as eradication of BRD in beef calves would increase the whole beef sector's productivity by 4.7-5.5% while eradication in other production stages would result in lower productivity gain in their respective sectors. However, the analysis performed at compartment level showed that, in both the beef and dairy sector, young bull and veal feedlot enterprises derive more economic benefits from BRD eradication for their own compartment (increase in productivity of 8.7-12.8% for beef young bulls) than the breeding farms (increase in productivity of 5.1-6% for beef calves), which may limit the investments in BRD control.

Pathogens, patterns of pneumonia, and epidemiologic risk factors associated with respiratory disease in recently weaned cattle in Ireland

We examined the pathogens, morphologic patterns, and risk factors associated with bovine respiratory disease (BRD) in 136 recently weaned cattle ("weanlings"), 6-12 mo of age, that were submitted for postmortem examination to regional veterinary laboratories in Ireland. A standardized sampling protocol included routine microbiologic investigations as well as polymerase chain reaction and immunohistochemistry. Lungs with histologic lesions were categorized into 1 of 5 morphologic patterns of pneumonia. Fibrinosuppurative bronchopneumonia (49%) and interstitial pneumonia (48%) were the morphologic patterns recorded most frequently. The various morphologic patterns of pulmonary lesions suggest the involvement of variable combinations of initiating and compounding infectious agents that hindered any simple classification of the etiopathogenesis of the pneumonias. Dual infections were detected in 58% of lungs, with Mannheimia haemolytica and Histophilus somni most frequently recorded in concert. M. haemolytica (43%) was the most frequently detected respiratory pathogen; H. somni was also shown to be frequently implicated in pneumonia in this age group of cattle. Bovine parainfluenza virus 3 (BPIV-3) and Bovine respiratory syncytial virus (16% each) were the viral agents detected most frequently. Potential respiratory pathogens (particularly Pasteurella multocida, BPIV-3, and H. somni) were frequently detected (64%) in lungs that had neither gross nor histologic pulmonary lesions, raising questions regarding their role in the pathogenesis of BRD. The breadth of respiratory pathogens detected in bovine lungs by various detection methods highlights the diagnostic value of parallel analyses in respiratory disease postmortem investigation.

Illumina MiSeq 16S amplicon sequence analysis of bovine respiratory disease associated bacteria in lung and mediastinal lymph node tissue

Background

Bovine respiratory disease (BRD) is caused by growth of single or multiple species of pathogenic bacteria in lung tissue following stress and/or viral infection. Next generation sequencing of 16S ribosomal RNA gene PCR amplicons (NGS 16S amplicon analysis) is a powerful culture-independent open reference method that has recently been used to increase understanding of BRD-associated bacteria in the upper respiratory tract of BRD cattle. However, it has not yet been used to examine the microbiome of the bovine lower respiratory tract. The objective of this study was to use NGS 16S amplicon analysis to identify bacteria in post-mortem lung and lymph node tissue samples harvested from fatal BRD cases and clinically healthy animals. Cranial lobe and corresponding mediastinal lymph node post-mortem tissue samples were collected from calves diagnosed as BRD cases by veterinary laboratory pathologists and from clinically healthy calves. NGS 16S amplicon libraries, targeting the V3-V4 region of the bacterial 16S rRNA gene were prepared and sequenced on an Illumina MiSeq. Quantitative insights into microbial ecology (QIIME) was used to determine operational taxonomic units (OTUs) which corresponded to the 16S rRNA gene sequences.

Results

Leptotrichiaceae, Mycoplasma, Pasteurellaceae, and Fusobacterium were the most abundant OTUs identified in the lungs and lymph nodes of the calves which died from BRD. Leptotrichiaceae, Fusobacterium, Mycoplasma, Trueperella and Bacteroides had greater relative abundances in post-mortem lung samples collected from fatal cases of BRD in dairy calves, compared with clinically healthy calves without lung lesions. Leptotrichiaceae, Mycoplasma and Pasteurellaceae showed higher relative abundances in post-mortem lymph node samples collected from fatal cases of BRD in dairy calves, compared with clinically healthy calves without lung lesions. Two Leptotrichiaceae sequence contigs were subsequently assembled from bacterial DNA-enriched shotgun sequences.

Conclusions

The microbiomes of the cranial lung lobe and mediastinal lymph node from calves which died from BRD and from clinically healthy H-F calves have been characterised. Contigs corresponding to the abundant Leptotrichiaceae OTU were sequenced and found not to be identical to any known bacterial genus. This suggests that we have identified a novel bacterial species associated with BRD.

Electronic supplementary material

The online version of this article (doi:10.1186/s12917-017-1035-2) contains supplementary material, which is available to authorized users.

Effect of bovine respiratory disease during the receiving period on steer finishing performance, efficiency, carcass characteristics, and lung scores

Bovine respiratory disease (BRD) is responsible for the majority of morbidity, mortality, and production losses occurring in feedlots. This experiment evaluated the effects of BRD incidence on subsequent finishing performance, efficiency, carcass characteristics, and lung scores of steers. Crossbred steers (n = 516) were monitored daily for clinical signs of BRD (BRD attributed morbidity and mortality were 66.5 and 13.2%, respectively). A subset of calves (n = 174) were grouped by the number of times treated for BRD (BRDX) and randomly allocated to finishing pens. The BRDX experimental groups included never treated for BRD (0X; 8 pens) and treated 1 time (1X; 8 pens), 2 times (2X; 8 pens), or 3 or 4 times (3/4X; 8 pens). Arrival BW was not different among BRDX groups (P = 0.17); however, BRDX during the receiving period decreased performance, resulting in BW of 324, 316, 285, and 260 kg for 0X, 1X, 2X, and 3/4X, respectively, at the start of finishing (P < 0.001). Ultrasound estimates, BW, and visual appraisal were used to target a common body composition (average days on feed = 182). With increasing BRDX, days on feed increased linearly (P = 0.002), whereas HCW, DP, rib eye area, QG, and unconsolidated lungs decreased linearly (P ≤ 0.03). These results suggest that with additional days on feed, calves treated multiple times for BRD are able to reach similar compositional endpoints as their untreated cohorts; however, it may not be possible for these calves to reach the same QG and carcass yield.

Determination of value of bovine respiratory disease control using a remote early disease identification system compared with conventional methods of metaphylaxis and visual observations

Mitigation of the deleterious effects of bovine respiratory disease (BRD) is an important issue in the cattle industry. Conventional management of calves at high risk for BRD often includes mass treatment with antimicrobials at arrival followed by visual observation for individual clinical cases. These methods have proven effective; however, control program efficacy is influenced by the accuracy of visual observation. A remote early disease identification (REDI) system has been described that monitors cattle behavior to identify potential BRD cases. The objective of this research was to compare health and performance outcomes using either traditional BRD control (visual observation and metaphylaxis) or REDI during a 60-d postarrival phase in high-risk beef calves. The randomized controlled clinical trial was performed in 8 replicates at 3 different facilities over a 19-mo period. In each replicate, a single load of calves was randomly allocated to receive either conventional management (CONV; total = 8) or REDI (total = 8) as the method for BRD control. Cattle were monitored with each diagnostic method for the first 30 d on feed and performance variables were collected until approximately 60 d after arrival. Statistical differences ( < 0.10) were not identified in common performance (ADG) or health (morbidity, first treatment success, and mortality risk) among the treatment groups. Calves in the REDI pens had a lower ( < 0.01) average number of days on feed at first treatment (9.1 ± 1.2 d) compared with CONV pens (15.8 ± 1.2 d). There were no statistical differences ( > 0.10) in risk of BRD treatment and REDI calves were not administered antimicrobials at arrival; therefore, REDI calves had a lower ( < 0.01) average number of doses of antimicrobials/calf (0.75 ± 0.1 doses) compared with CONV calves (1.67 ± 0.1 doses). In this trial, the REDI system was comparable to conventional management with the potential advantages of earlier BRD diagnosis and decreased use of antimicrobials. Further research should be performed to evaluate the longer-term impacts of the 2 systems.

Comparison of tulathromycin and tilmicosin on the prevalence and severity of bovine respiratory disease in feedlot cattle in association with feedlot performance, carcass characteristics, and economic factors

The objectives of this study were to 1) quantify effects of metaphylactic treatment for bovine respiratory disease (BRD) on growth performance, carcass characteristics, and lung lesion prevalence and severity; 2) evaluate the association of lung lesion prevalence and severity with carcass characteristics; and 3) evaluate effects of therapeutic treatment on carcass characteristics and lung lesion prevalence and severity. The study was conducted at a commercial feedlot in the Texas Panhandle in which steers (n = 2,336) initially weighing 312.1 ± 9.6 kg were sourced from auction markets and allocated in a randomized complete block design to 1 of 3 treatments (no metaphylactic [no antimicrobial drug {ND}] treatment, tilmicosin at 10 mg/kg BW [TIL], and tulathromycin at 2.5 mg/kg BW [TUL]). Lungs of all steers were evaluated during harvest to assess presence and severity of pneumonic lesions in the anteroventral lobes and the presence and severity of pleural adherences. Compared to the ND treatment, steers treated via metaphylactic therapy had greater (P < 0.05) metaphylactic cost, ADG, shrunk final BW, dressed carcass yield, HCW, 12th rib fat, calculated empty body fat (EBF), and gross revenue, concurrent with reduced (P < 0.05) BRD treatment costs and financial losses from BRD death and railed cattle, cumulatively resulting in greater financial returns. Lung lesions were present in 64.3% of lungs and were distributed similarly between metaphylactic treatments (63.9%) and ND (65.1%) cattle. Steers with advanced lung lesions present at harvest were associated with reduced (P < 0.05) HCW, KPH, 12th rib fat, calculated yield grades, marbling scores, and calculated EBF as compared to steers without lung lesions. Steers pulled for BRD had increased (P < 0.01) incidence of advanced lung lesions, mortality, and railers with decreased (P < 0.05) HCW, 12th rib fat, KPH, marbling score, calculated EBF, and percentage choice carcasses when compared to non-BRD event steers. From the results of this study, controlling BRD through the use of metaphylactic treatments on arrival in heavier cattle improved financial returns primarily driven by reductions in cost of death loss and railers.

Relationship between rectal temperature at first treatment for bovine respiratory disease complex in feedlot calves and the probability of not finishing the production cycle

OBJECTIVE-To determine the relationship between rectal temperature at first treatment for bovine respiratory disease complex (BRDC) in feedlot calves and the probability of not finishing the production cycle. DESIGN-Retrospective data analysis. ANIMALS-344,982 calves identified as having BRDC from 19 US feedlots from 2000 to 2009. PROCEDURES-For each calf, data for rectal temperature at initial treatment for BRDC and various performance and outcome variables were analyzed. A binary variable was created to identify calves that did not finish (DNF) the production cycle (died or culled prior to cohort slaughter). A mixed general linear model and receiver operating characteristic curve were created to evaluate associations of rectal temperature, number of days in the feedlot at time of BRDC diagnosis, body weight, quarter of year at feedlot arrival, sex, and all 2-way interactions with rectal temperature with the probability that calves DNF. RESULTS-27,495 of 344,982 (7.97%) calves DNF. Mean rectal temperature at first treatment for BRDC was 40.0°C (104°F). As rectal temperature increased, the probability that a calf DNF increased; however, that relationship was not linear and was influenced by quarter of year at feedlot arrival, sex, and number of days in the feedlot at time of BRDC diagnosis. Area under the receiver operating characteristic curve for correct identification of a calf that DNF was 0.646. CONCLUSIONS AND CLINICAL RELEVANCE-Rectal temperature of feedlot calves at first treatment for BRDC had limited value as a prognostic indicator of whether those calves would finish the production cycle.