Effects of bovine respiratory disease on the plasma metabolome of beef steers during the receiving period

The study aimed to investigate the impact of Bovine Respiratory Disease (BRD) on the metabolism of beef steers during a 35-d receiving period using plasma metabolomics. In this study, 77 newly weaned crossbred (Angus × Hereford) beef steers (BW = 206 ± 12 kg and age = 180 ± 17 days) were categorized into two groups: Healthy and Sick groups. The Sick group comprised beef steers diagnosed with BRD at any time during the 35-day period (n = 31), while the Healthy group did not show any signs of BRD (n = 46). Blood samples were collected from the coccygeal vessels on day 35, and plasma samples were subjected to targeted metabolomics analysis using Nuclear Magnetic Resonance spectroscopy. Data and statistical analyses, including biomarker and pathway enrichment analyses, were performed using Metaboanalyst 5.0. Results of the growth performance showed that sick steers had lower (p ≤ 0.05) ADG (1.44 vs. 1.64 kg/d) and higher (p = 0.01) feed:gain ratio (3.57 vs. 3.13) compared to healthy steers. A total of 50 metabolites were quantified. The partial least squares discriminant scores plot showed a slight separation between the two groups of steers, indicating some metabolic differences. Furthermore, the plasma concentrations of four metabolites (sarcosine, methionine, dimethyl sulfone, and L-histidine) were greater (p ≤ 0.05) in healthy steers compared to sick steers. Among these metabolites, sarcosine and methionine qualified as candidate biomarkers associated with BRD infection based on an area under the curve >0.70. Additionally, quantitative enrichment analysis revealed that cysteine and methionine metabolism was enriched in healthy steers compared to sick steers. This suggests that these metabolic pathways may play a role in the response to BRD infection. The findings of this study highlight the altered plasma metabolome in steers with BRD during the receiving period. Understanding these metabolic changes can contribute to the development of effective management strategies and nutritional interventions to mitigate the negative impact of BRD on beef cattle health and immune function.

GWAS and genetic and phenotypic correlations of plasma metabolites with complete blood count traits in healthy young pigs reveal implications for pig immune response

Introduction: In this study estimated genetic and phenotypic correlations between fifteen complete blood count (CBC) traits and thirty-three heritable plasma metabolites in young healthy nursery pigs. In addition, it provided an opportunity to identify candidate genes associated with variation in metabolite concentration and their potential association with immune response, disease resilience, and production traits.

Methods: The blood samples were collected from healthy young pigs and Nuclear Magnetic Resonance (NMR) was used to quantify plasma metabolites. CBC was determined using the ADVIA® 2120i Hematology System. Genetic correlations of metabolite with CBC traits and single step genome-wide association study (ssGWAS) were estimated using the BLUPF90 programs.

Results: Results showed low phenotypic correlation estimates between plasma metabolites and CBC traits. The highest phenotypic correlation was observed between lactic acid and plasma basophil concentration (0.36 ± 0.04; p < 0.05). Several significant genetic correlations were found between metabolites and CBC traits. The plasma concentration of proline was genetically positively correlated with hemoglobin concentration (0.94 ± 0.03; p < 0.05) and L-tyrosine was negatively correlated with mean corpuscular hemoglobin (MCH; −0.92 ± 0.74; p < 0.05). The genomic regions identified in this study only explained a small percentage of the genetic variance of metabolites levels that were genetically correlated with CBC, resilience, and production traits.

Discussion: The results of this systems approach suggest that several plasma metabolite phenotypes are phenotypically and genetically correlated with CBC traits, suggesting that they may be potential genetic indicators of immune response following disease challenge. Genomic analysis revealed genes and pathways that might interact to modulate CBC, resilience, and production traits.

NMR-based metabolomics of plasma from dairy calves infected with two primary causal agents of bovine respiratory disease (BRD)

Each year, bovine respiratory disease (BRD) results in significant economic loss in the cattle sector, and novel metabolic profiling for early diagnosis represents a promising tool for developing effective measures for disease management. Here, ¹H-nuclear magnetic resonance (¹H-NMR) spectra were used to characterize metabolites from blood plasma collected from male dairy calves (n = 10) intentionally infected with two of the main BRD causal agents, bovine respiratory syncytial virus (BRSV) and Mannheimia haemolytica (MH), to generate a well-defined metabolomic profile under controlled conditions. In response to infection, 46 metabolites (BRSV = 32, MH = 33) changed in concentration compared to the uninfected state. Fuel substrates and products exhibited a particularly strong effect, reflecting imbalances that occur during the immune response. Furthermore, ¹H-NMR spectra from samples from the uninfected and infected stages were discriminated with an accuracy, sensitivity, and specificity ≥ 95% using chemometrics to model the changes associated with disease, suggesting that metabolic profiles can be used for further development, understanding, and validation of novel diagnostic tools.

Treatment with 2 commercial antibiotics reduced clinical and systemic signs of pneumonia and the abundance of pathogenic bacteria in the upper respiratory tract of preweaning dairy calves

The aim of this study was to evaluate the effect of therapeutically administered tildipirosin or florfenicol + flunixin meglumine for the treatment of bovine respiratory disease (BRD) accompanied by fever in calves before weaning compared with diseased and untreated animals. As specific objectives, we evaluated the composition of the bacterial microbiota of the upper respiratory tract (URT) and blood and health parameters of the animals. Preweaning Holstein female calves diagnosed with naturally acquired pneumonia were randomly assigned to one of the following experimental groups on the day of diagnosis (d 0): (1) TLD (n = 36): single subcutaneous injection with 4 mg/kg tildipirosin; (2) FLF (n = 33): single subcutaneous injection with an antimicrobial (40 mg/kg florfenicol) combined with a nonsteroidal anti-inflammatory drug (2.2 mg/kg flunixin meglumine); and (3) NEG (n = 35): no treatment within the first 5 d following enrollment. The NEG treatment group was closely monitored for 5 d, and calves were removed from the study following a standardized late treatment protocol, when necessary, to minimize health concerns. Healthy untreated calves (CTR; n = 31) were also selected for the study and used as controls. Blood samples used for biochemical analysis and nasopharyngeal swabs used for evaluation of URT microbiota were collected daily from d 0 until d 5 and then weekly until weaning. Next-generation sequencing of the 16S rRNA gene was used to assess the URT microbiota at the phylum and genus levels. Clinical signs associated with pneumonia and otitis media were assessed daily, as was the need for antibiotic interventions. Calves in the TLD and FLF groups had faster recovery from fever within the first 5 d after enrollment. In addition, antibiotic-treated calves reached the same serum haptoglobin levels as healthy calves on d 2 after diagnosis, whereas calves in the NEG group had higher haptoglobin levels than the CTR group until at least d 5 after BRD diagnosis. Calves in the TLD and FLF groups had a lower risk of treatment for pneumonia (FLF = 22.8%; TLD = 27.7%) from d 5 to weaning than calves in the NEG group (54.7%). Furthermore, FLF treatment had a significantly lower risk of nasal discharge, otitis media, and treatment failure compared with the NEG group, but did not differ from the TLD group. Differences in the composition of the URT microbiota were found between groups, and the genus Mycoplasma was the most abundant in samples collected from the URT of calves with and without pneumonia. Both drugs were effective in reducing the mean relative abundance (MRA) of important genera associated with pneumonia (Mannheimia and Pasteurella), although an increase in Mycoplasma MRA was observed for tildipirosin-treated calves. In conclusion, both drugs were effective in reducing the inflammatory signs of pneumonia and the need for antimicrobial treatment after enrollment compared with no treatment. In addition, both TLD and FLF were effective in reducing the MRA of important bacterial genera associated with pneumonia; however, TLD treatment was associated with increased Mycoplasma MRA compared with healthy and untreated calves.

Associations of carcass weight and trimming loss with cull dairy cow health observations collected at slaughter

Cull dairy cows account for around 27 percent of total head EU beef and veal production. For the Netherlands specific, even 42 percent (European Commission, 2022). As they are primarily kept to produce milk, red meat production is an additional source of revenue for dairy farmers. Insights in postmortem health observations that are not always visible on the living animal such as heart or liver issues, bruises, adhesions and injuries on the locomotor system, may contain valuable information for farmers to increase revenue and reduce losses in red meat production from cull dairy cows. Our goal was to obtain insights in the association of postmortem health observations with carcass weight and trimming losses. Data of 592,268 slaughter cows were available for analysis and models were built to explain carcass and trimming loss by the postmortem health observations. Carcass weight is lower for younger cows (-3.2 to -84.9 kg), cows with multiple health observations (-7.4 to -34.3 kg) and specific observations for the locomotor system (-16.7 to -22.7 kg), back (-17.9 kg), hindquarter (-21.6 kg) and chest and ribs (-15.5 to -27.6 kg). Total number of health observations (+2.0 to +6.5 kg), observations on the locomotor system (+3.3 to +5.4 kg) and on the chest and ribs (+2.2 to +9.8 kg) were the main predictors for trimming loss. Carcass weight is more affected by systemic health issues and diseases prior to slaughter leading to a negative energy balance and consequently reduced carcass weight. Trimming loss is more a consequence of the focus on meat quality and food safety in the slaughter process. Better understanding of the effect of on-farm management, on health, carcass weight and trimming loss will provide new insights for farmers and veterinarians but will also give them more action perspective to improve dairy farm preventive management and reduce losses at slaughter.

Integrative Analysis of the Nasal Microbiota and Serum Metabolites in Bovines with Respiratory Disease by 16S rRNA Sequencing and Gas Chromatography/Mass Selective Detector-Based Metabolomics

Bovine respiratory disease (BRD) continues to pose a serious threat to the cattle industry, resulting in substantial economic losses. As a multifactorial disease, pathogen infection and respiratory microbial imbalance are important causative factors in the occurrence and development of BRD. Integrative analyses of 16S rRNA sequencing and metabolomics allow comprehensive identification of the changes in microbiota and metabolism associated with BRD, making it possible to determine which pathogens are responsible for the disease and to develop new therapeutic strategies. In our study, 16S rRNA sequencing and metagenomic analysis were used to describe and compare the composition and diversity of nasal microbes in healthy cattle and cattle with BRD from different farms in Yinchuan, Ningxia, China. We found a significant difference in nasal microbial diversity between diseased and healthy bovines; notably, the relative abundance of Mycoplasma bovis and Pasteurella increased. This indicated that the composition of the microbial community had changed in diseased bovines compared with healthy ones. The data also strongly suggested that the reduced relative abundance of probiotics, including Pasteurellales and Lactobacillales, in diseased samples contributes to the susceptibility to bovine respiratory disease. Furthermore, serum metabolomic analysis showed altered concentrations of metabolites in BRD and that a significant decrease in lactic acid and sarcosine may impair the ability of bovines to generate energy and an immune response to pathogenic bacteria. Based on the correlation analysis between microbial diversity and the metabolome, lactic acid (2TMS) was positively correlated with Gammaproteobacteria and Bacilli and negatively correlated with Mollicutes. In summary, microbial communities and serum metabolites in BRD were characterized by integrative analysis. This study provides a reference for monitoring biomarkers of BRD, which will be critical for the prevention and treatment of BRD in the future.

A systematic review of the utility of biomarkers as aids in the early diagnosis and outcome prediction of bovine respiratory disease complex in feedlot cattle

Bovine respiratory disease complex (BRDC) is a common, serious problem in feedlot cattle worldwide. Early diagnosis and outcome prediction are critical for making decisions to prevent economic loss and to limit antimicrobial use. Diagnosing BRDC is commonly based on visual signs and behavioral changes; both assessments are considered to have low diagnostic accuracy. Biomarkers are important for supporting the diagnosis of BRDC, determining the necessity and potential outcomes of treatment, and assisting in research in which differentiating diseased animals is required. There are few reviews summarizing the biomarkers available and utilized. We systematically evaluated the detection and prognostic potential of biomarkers from the literature published between January 1990 and December 2020. We performed a descriptive analysis of 5 biomarker categories: acute-phase proteins, stress-related hormones, other blood biomarkers, omics biomarkers, and non-blood biomarkers. The retrieved articles consisted of studies or trials that assessed the detection value and treatment and/or outcome prediction efficacy of biomarkers for BRDC in feedlot cattle; 23 manuscripts for review and analysis satisfied the selection criteria. Based on our review, we cannot recommend a specific biomarker as the sole method for the early detection or outcome prediction for BRDC, given that the application and efficacy of biomarkers varies in different situations. Our systematic review may serve as a reference for clinical and research investigations of early detection and outcome prediction of BRDC.

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.

Feeding Saccharomyces cerevisiae fermentation products lessens the severity of a viral-bacterial coinfection in preweaned calves

We have previously reported that supplementation with Saccharomyces cerevisiae fermentation products (SCFP) ameliorates clinical signs and lung pathology following experimental bovine respiratory syncytial virus (BRSV) infection in preweaned dairy calves. The objectives of this study were to determine the effect of SCFP supplementation on the metabolic and endocrine responses, and disease outcome of a viral-bacterial coinfection in preweaned calves. Twenty-seven, 1- to 2-d-old Holstein-Angus cross calves were enrolled in the study; one SCFP calf was removed from the trial during the pre-challenge phase due to complications from nephritis. Calves were assigned to two treatment groups: control or SCFP-treated, base milk replacer with 1 g/d SCFP (Smartcare, soluble formula) and calf starter top dressed with 5 g/d SCFP (NutriTek, insoluble formula). Calves were infected with BRSV on day 21, followed 6 d later by intratracheal inoculation with Pasteurella multocida (PM). Calves were euthanized on day 10 post-viral infection. Calves receiving SCFP had reduced thoracic ultrasonography scores on day 7 post-viral infection (P = 0.03) and a tendency toward reduced scores on day 10 post-viral infection (P = 0.09). Calves receiving SCFP also had less severe lung pathology scores at necropsy (P = 0.06). No differences between treatments were observed in lung viral loads (P = 0.48) or bacterial lung recovery (P = 0.34); however, there was a distinction in the lung location for PM recovery, with PM isolated more frequently from the cranial lobes in SCFP-treated calves, but more frequently from the caudal lobes of control calves. Calves treated with SCFP tended (P = 0.07) to have higher serum IL-6 concentrations following the coinfection. Calves treated with SCFP had lower concentrations of serum nonesterified fatty acids and beta-hydroxybutyric acid compared with controls following experimental challenge (P = 0.03 and P = 0.08, respectively), suggesting metabolic changes favoring growth and development. There were no differences between groups in gene expression of insulin receptor, insulin-like growth factor 1 (IGF-1), IGF-1 receptor (IGF-1R), growth hormone receptor, or haptoglobin in the liver. Results from this study suggest that supplementing with SCFP may moderate the impact of a respiratory viral-bacterial coinfection on preweaned calves through metabolic and immune modifications.

Heritability and genetic correlations of plasma metabolites of pigs with production, resilience and carcass traits under natural polymicrobial disease challenge

Metabolites in plasma of healthy nursery pigs were quantified using nuclear magnetic resonance. Heritabilities of metabolite concentration were estimated along with their phenotypic and genetic correlations with performance, resilience, and carcass traits in growing pigs exposed to a natural polymicrobial disease challenge. Variance components were estimated by GBLUP. Heritability estimates were low to moderate (0.11 ± 0.08 to 0.19 ± 0.08) for 14 metabolites, moderate to high (0.22 ± 0.09 to 0.39 ± 0.08) for 17 metabolites, and highest for l-glutamic acid (0.41 ± 0.09) and hypoxanthine (0.42 ± 0.08). Phenotypic correlation estimates of plasma metabolites with performance and carcass traits were generally very low. Significant genetic correlation estimates with performance and carcass traits were found for several measures of growth and feed intake. Interestingly the plasma concentration of oxoglutarate was genetically negatively correlated with treatments received across the challenge nursery and finisher (− 0.49 ± 0.28; P < 0.05) and creatinine was positively correlated with mortality in the challenge nursery (0.85 ± 0.76; P < 0.05). These results suggest that some plasma metabolite phenotypes collected from healthy nursery pigs are moderately heritable and genetic correlations with measures of performance and resilience after disease challenge suggest they may be potential genetic indicators of disease resilience.

Genomic Heritability and Genome-Wide Association Studies of Plasma Metabolites in Crossbred Beef Cattle

Metabolites, substrates or products of metabolic processes, are involved in many biological functions, such as energy metabolism, signaling, stimulatory and inhibitory effects on enzymes and immunological defense. Metabolomic phenotypes are influenced by combination of genetic and environmental effects allowing for metabolome-genome-wide association studies (mGWAS) as a powerful tool to investigate the relationship between these phenotypes and genetic variants. The objectives of this study were to estimate genomic heritability and perform mGWAS and in silico functional enrichment analyses for a set of plasma metabolites in Canadian crossbred beef cattle. Thirty-three plasma metabolites and 45,266 single nucleotide polymorphisms (SNPs) were available for 475 animals. Genomic heritability for all metabolites was estimated using genomic best linear unbiased prediction (GBLUP) including genomic breed composition as covariates in the model. A single-step GBLUP implemented in BLUPF90 programs was used to determine SNP P values and the proportion of genetic variance explained by SNP windows containing 10 consecutive SNPs. The top 10 SNP windows that explained the largest genetic variation for each metabolite were identified and mapped to detect corresponding candidate genes. Functional enrichment analyses were performed on metabolites and their candidate genes using the Ingenuity Pathway Analysis software. Eleven metabolites showed low to moderate heritability that ranged from 0.09 ± 0.15 to 0.36 ± 0.15, while heritability estimates for 22 metabolites were zero or negligible. This result indicates that while variations in 11 metabolites were due to genetic variants, the majority are largely influenced by environment. Three significant SNP associations were detected for betaine (rs109862186), L-alanine (rs81117935), and L-lactic acid (rs42009425) based on Bonferroni correction for multiple testing (family wise error rate <0.05). The SNP rs81117935 was found to be located within the Catenin Alpha 2 gene (CTNNA2) showing a possible association with the regulation of L-alanine concentration. Other candidate genes were identified based on additive genetic variance explained by SNP windows of 10 consecutive SNPs. The observed heritability estimates and the candidate genes and networks identified in this study will serve as baseline information for research into the utilization of plasma metabolites for genetic improvement of crossbred beef cattle.

Identification of biomarkers measured upon arrival associated with morbidity, mortality, and average daily gain in grain-fed veal calves

There is a strong need for management strategies that help reduce the incidence of disease and subsequent antimicrobial use in the veal industry. Biomarkers could serve as useful tools that allow producers to take preventative measures before clinical problems occur. The objective of this prospective cohort study was to identify biomarkers measured upon arrival associated with morbidity, mortality, and average daily gain (ADG) in grain-fed veal calves. Upon arrival at a grain-fed veal facility in Ontario, Canada, calves were weighed and health-scored using a standardized health-scoring system. Several metabolites were measured including creatine kinase (CK), cholesterol, haptoglobin, manganese, serum total protein, iron, cobalt, zinc, selenium, molybdenum, and IgG. Farm personnel treated calves according to their farm protocol and weighed them at 78 d after arrival. Performance, treatment, and mortality records from the facility were used for analysis. Multivariable Cox proportional hazard models were created to evaluate metabolic biomarkers associated with morbidity and mortality. A mixed linear regression model was created to determine biomarkers associated with ADG. A total of 992 male dairy calves were evaluated at arrival from January to December 2017. Of the calves evaluated, 74 calves (7.5%) died and 877 (88.4%) were treated for illness over the 11-wk period under observation. Higher levels of haptoglobin and molybdenum were associated with a greater hazard of morbidity, whereas higher weight upon arrival and higher levels of both CK and IgG were associated with a reduced hazard of morbidity. For mortality, higher weight upon arrival and higher levels of cholesterol and IgG were associated with a lower hazard of mortality occurring over the 78-d period of observation. Higher weight, cholesterol, copper, CK, iron, and IgG were associated with increased ADG, whereas increased zinc and haptoglobin were negatively associated with ADG. These results demonstrate that certain biomarkers could be used to identify high-risk calves when measured upon arrival at a veal facility. Future research should focus on determining the utility of these biomarkers to selectively target intervention strategies to improve ADG and reduce morbidity and mortality.

Bovine Respiratory Disease Influences on Nutrition and Nutrient Metabolism

Bovine respiratory disease (BRD) complex remains one of the greatest challenges facing beef cattle producers, veterinarians, and feedlot managers. In receiving, stocker/backgrounding, and feedlot cattle, BRD has been associated with decreased dry matter intake and daily gain, resulting in economic losses during the feeding period. Inflammation associated with BRD has the potential to decrease carcass yield and quality. Newly received calves are at various risks to contract BRD. Proper nutrition for newly received calves is key to recovery from stress associated with weaning and transport. This article reviews nutrient impacts on BRD and BRD impacts on nutrient metabolism.

Immune and metabolic responses of beef heifers supplemented with Saccharomyces cerevisiae to a combined viral-bacterial respiratory disease challenge

Two treatments were evaluated in heifers to determine the effects of a yeast supplement on immune and metabolic responses to a combined (tandem viral-bacterial) respiratory disease challenge. Thirty-two beef heifers (325 ± 20.1 kg BW) were selected from a larger population previously assigned to one of two treatments: Control (CON), receiving no yeast supplement in the diet, or yeast (YST), CON diet plus a combination live yeast (2.5 g·heifer^-1·d^-1) and yeast cell wall (2.5 g·heifer^-1·d^-1) supplement (Phileo Lesaffre Animal Care, Milwaukee, WI). Heifers were maintained on treatments for 31 d prior to the challenge. On day -3 all heifers were fitted with an indwelling vaginal temperature recording device, received an intranasal challenge with 2 × 10⁸ plaque-forming units of bovine herpesvirus-1 (BHV-1), and placed in outdoor pens. On day 0, all heifers were fitted with an indwelling jugular catheter, challenged intratracheally with an average dose of 3.0 × 10⁷ colony-forming units (cfu) of Mannheimia haemolytica in 100 mL media, and were transferred into individual stanchions in an enclosed, environmentally controlled barn. Whole blood samples were collected at -72 h and at 0, 2, 4, 6, 8, 12, 24, 36, 48, 60, and 72 h (hematology) and at 0, 1, 2, 3, 4, 5, 6, 7, 8, 12, 24, 36, 48, 60, and 72 h (serum isolation) relative to M. haemolytica challenge (0 h). Data were analyzed using the MIXED procedure of SAS specific for repeated measures with fixed effects of treatment, time, and the treatment × time interaction. Vaginal temperature and cortisol concentrations were similar between treatments (P ≥ 0.39). Although total leukocyte count following BHV-1 challenge was similar between treatments (P = 0.21), there was a tendency (P = 0.07) for CON heifers to have greater neutrophil counts than YST heifers. Serum haptoglobin concentration was similar between treatments (P = 0.13). Heifers in the YST treatment had similar serum glucose concentrations (P = 0.25) and decreased serum concentrations of urea nitrogen compared to CON (P = 0.03). Dietary treatment did not affect serum nonesterified fatty acid concentrations (P = 0.37). Nasal lesion score severity (0-4) tended (P = 0.07) to be decreased in YST compared to CON (2.5 vs. 3.19 ± 0.26), while water intake tended to be increased in YST (P = 0.06). Feeding a yeast supplement had little effect on the acute-phase response but improved metabolic outcomes in heifers during a respiratory disease challenge.

Evaluating Potential Biomarkers of Health and Performance in Veal Calves

Veal calves undergo many challenges in the early stages of their life. Such challenges, including mixing procedures and transportation of calves to the veal farm, may have a negative influence on growth rate, feed intake, metabolism, immunity and disease susceptibility of calves. As a consequence, many hematological, physiological, metabolic and immunological parameters of stressed calves might be altered on arrival at the veal farm. Some of these response variables might be useful as biomarkers of performance of calves at the veal farm as they might provide information about an ongoing disease process, or may predict future diseases. Biomarkers might be helpful to group and manage calves in different risk categories after arrival. By adopting treatment decisions and protocols on a risk-group or individual basis, it would be possible to improve animal health and reduce both disease incidence and antibiotic use. Moreover, the use of biomarkers might be an economically feasible approach as some of them do not need invasive techniques and others can be measured in blood already taken during routine checks. Previous literature mainly assessed the physiological responses of calves to transportation. However, information on the link between on-farm arrival data and future health and performance of veal calves is limited. This review, therefore, examined a wide range of papers and aimed to identify potential biomarkers of future health and performance.

Association of preweaning and weaning serum cortisol and metabolites with ADG and incidence of respiratory disease in beef cattle

The objectives of this experiment were to determine the association of circulating cortisol, lactate, and glucose at, and prior to, weaning with ADG and incidences of bovine respiratory disease (BRD) in beef cattle. A blood sample was collected approximately 3 wk prior to weaning and at weaning from genetically diverse steers and heifers ( = 451). Cattle were weighed periodically throughout the study and ADG was calculated for the preweaning period (152 ± 15 d), the receiving period (45 d postweaning), the finishing period (200 d), and total postweaning ADG. Incidences of BRD were recorded and analyzed as a binary trait. Lung lesions were recorded at slaughter. Preweaning serum cortisol concentrations were positively associated ( = 0.040) with receiving ADG and explained 0.74% of the variance of receiving ADG. Preweaning glucose concentrations were positively associated ( < 0.001) with preweaning ADG and negatively associated with receiving ( = 0.003), finishing ( = 0.008), and total postweaning ADG ( = 0.002) and explained 2.0% of the variance in total postweaning ADG. Variation in preweaning serum glucose concentrations could be indicative of variation in milk consumption, and therefore indicate calves receiving less milk grow slower prior to weaning, but experience compensatory gain postweaning. Cattle that were diagnosed with BRD ( = 130) grew slower during the receiving phase ( = 0.004), but total postweaning ADG was not different from cattle not diagnosed with BRD ( = 0.683). Additionally, cattle that were diagnosed with BRD in the feedlot tended ( = 0.062) to have slightly lower preweaning serum glucose concentrations. Using a logistic regression analysis, none of the serum variables measured at or before weaning were predictive of developing BRD ( > 0.180). Weaning serum glucose concentrations tended to be predictive of the presence of lung lesions at weaning ( = 0.060). These data indicate that glucose measured early in life is associated with growth rate, and could indicate that carbohydrate metabolism could contribute to variation in ADG.

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.

Effect of health status on fattening performance in young crossbred polish Holstein-Friesian × Limousin Bulls and steers

The aim of this study was to determine the effect of disease incidence on selected parameters of cattle fattening performance and carcass quality, and the fatty acid profile of beef. The experimental materials comprised 16 bulls and 16 steers, Polish Holstein-Friesian × Limousin crossbreeds (including 10 healthy and six treated animals of each category). At 5 weeks of age, bloodless castration was carried out using a rubber elastrator. The calves were fed milk replacer provided in automatic feeding stations. Until 540 days of age, the animals were fattened in an Animal Research Laboratory equipped with the Roughage Intake Control (RIC) system (Insentec, the Netherlands). In comparison with healthy (untreated) bulls and steers, sick (treated) animals had lower average body weight at 180 days of age, by 37 kg (P ≤ 0.05) and lower average final body weight at 540 days of age, by 56 kg (P ≤ 0.05). Sick animals were characterized by lower feed intake and worse feed efficiency (not statistically significant differences). Hot carcass weight reached 318 kg in healthy animals and 258 kg in treated bulls (P ≤ 0.05). In treated steers, the percentage of lean meat and bones in the three-rib section was higher and the percentage of fat was lower, compared with their healthy counterparts (P ≤ 0.01). There was a category × health status interaction for carcass tissue composition. There were no significant influences of type of sickness on analyzed traits. In comparison with healthy steers, intramuscular fat of Musculus longissimus dorsi (MLD) from treated steers had significantly (P ≤ 0.05) higher concentrations of polyunsaturated fatty acids (n-6 and n-3) and a lower content of conjugated linoleic acid.

Haematological and blood biochemical alterations associated with respiratory disease in calves

Respiratory diseases of cattle, particularly in young animals, represent the most important health and economic problem of cattle rearing. The aim of the present study was to evaluate the changes of selected blood indices in 25 calves aged 2–9 months suffering from etiologically undifferentiated chronic respiratory diseases. Blood samples were analysed for haematological indices and selected serum biochemistry variables. The results found in sick animals were compared with results from 25 healthy animals of the same age, housing and feeding system. Significant differences in means between the groups of clinically healthy and sick calves were found in 13 out of 24 evaluated indicators. In sick animals we found significantly higher mean concentrations of haemoglobin and total number of white blood cells (P < 0.05 and P < 0.01, respectively), as well as higher mean activity of AST and LDH (P < 0.01), concentrations of total proteins and total immunoglobulins (P < 0.001). Significantly lower mean values were recorded in the serum concentrations of albumin, creatinine and glucose (P < 0.001), as well as in the concentration of Mg (P < 0.01), P (P < 0.001), Fe and Zn (P < 0.05). The presented results suggest the effect of respiratory diseases in calves on several changes of haematological and selected serum biochemical indicators. They indicate that respiratory diseases did not lead only to direct disturbance of gas exchange and acid-base balance, but they also indirectly affect some other variables of blood biochemistry.

Assessment of L-lactatemia as a predictor of respiratory disease recognition and severity in feedlot steers

The bovine respiratory disease complex (BRD) is a major health issue in feedlot cattle and one of the primary reasons for antimicrobial use in the North American feedlot industry. The purpose of the present study was to assess blood L-lactate levels of feedlot steers at high risk of developing BRD during the early feeding period. Blood samples were obtained at initial processing and again after BRD confirmation (using bronchial lavage or thoracic ultrasound exam). The study involved 232 recently weaned steers received at a single research feedlot that were processed without metaphylactic antimicrobial treatment. Blood samples were obtained for determination of L-lactatemia and temperament scores (very quiet or stoic [score 1], average [score 2] and very excited [score 3]) were systematically assigned at initial processing. A subsample of calves that were later confirmed as cases of BRD were sampled at first pull (day 0), and at subsequent observation points on days 3, 6, 9 and 15 following initial BRD diagnosis for blood lactate determination as a potential indicator of subsequent death. The clinical BRD cumulative incidence in the cohort was 38% (87/232). Temperament was associated with the probability of becoming a BRD case during the early feeding period. Stoic or very excited calves showed 2.2 times higher odds (95%CI: 1.3, 3.8) of becoming BRD cases compared to calves with average temperament. The impact of L-lactatemia differed by temperament strata. In calves with a temperament score of 2 (average temperament) every 1-log unit increase of lactatemia at processing resulted in 1.9 times higher odds (95% CI: 1.2, 3.1) of becoming a BRD case; this relationship was not significant in calves with a score of either 1 or 3. Twenty-nine confirmed BRD cases were studied for the dynamic lactate assessment analysis. L-lactate at first pull was not significantly different between survivors (median 3.3mmol/L; range 0.8-7.8mmol/L) and non-survivors (median 2.7mmol/L; range: 1.6-5.4mmol/L) steers. However, the dynamic assessment of L-lactatemia was associated with the hazard of death using Cox proportional hazard survival analysis. A 1-log increase of lactatemia increased the hazard of dying prior to the next observation by a factor of 36.5 (95% CI: 3.5-381.6). For calves showing a normal temperament score (i.e. temperament score of 2), a misclassification cost term analysis was conducted to identify potential L-lactate test thresholds for identifying future BRD steers. When planned test usage was for informing decision of administering or not a metaphylactic treatment at processing, experts agreed that false-negative (not treating a calf that would have benefit from treatment) to false-positive (wrongfully treating a calf that would have remained healthy) health costs ratio ranged from 8:1 to 20:1. In this situation, a threshold of 5mmol/L would have best informed treatment decision. When using L-lactate for informing the type of antimicrobial used at processing, false-negative to false-positive health costs ratio ranging from 1:1 to 3:1 could be expected and, again, a L-lactate threshold of 5.0mmol/L would have minimized the costs associated with calves' misclassification and could be used to identify calves that would benefit from a more efficient metaphylactic treatment. This study provides an interesting perspective on the potential application of chute-side markers or diagnostic tests to stratify the risk of future pull for BRD in cattle during processing in order to adapt antimicrobial treatments accordingly.

Growth and Development Symposium: Impacts of inflammation on cattle growth and carcass merit

Inflammation caused by bovine respiratory disease (BRD) continues to be one of the greatest challenges facing beef cattle producers and feedlot managers. Inflammation decreases DMI, ADG, and G:F in feedlot calves, decreasing growth rate and increasing days on feed, which results in economic losses during the feeding period. During the past decade, marketing of feedlot animals has changed from selling cattle on a live basis to a grid-based marketing system. When cattle are marketed on a live basis, the economic effects of BRD stop at increased health cost and decreased feedlot performance, carcass weight, and death loss. However, when cattle are marketed in a grid-based system, inflammation has the potential to also affect carcass cutability and quality. The effects of inflammation on feedlot cattle in regards to performance are well understood; however, specific effects on cattle growth and ultimately carcass merit are not as well described. Recent studies in feedlot cattle have indicated that the incidence of BRD decreases both HCW and marbling; however, mechanisms are not understood. Research in other species has demonstrated that during the acute phase response, pro-inflammatory cytokines promote skeletal muscle catabolism to supply AA and energy substrates for immune tissues. Further, during this early immune response, the liver changes its metabolic priorities to the production of acute phase proteins for use in host defense. Together these dramatic shifts in systemic metabolism may explain the detrimental effects on performance and carcass traits commonly associated with BRD in feedlot calves. Moreover, recent studies relative to human health have revealed complex multilevel interactions between the metabolic and immune systems, and highlighted inflammation as being a significant contributor to major metabolic diseases. The objective of this paper is to review data to help explain the economical and physiological effects of inflammation on cattle growth and carcass merit.

Effect of bovine respiratory disease during preconditioning on subsequent feedlot performance, carcass characteristics, and beef attributes

Heifers with expected increased risk of bovine respiratory disease (BRD; n = 360; initial BW = 241.3 +/- 16.6 kg) were assembled at a Kentucky order-buyer facility and delivered to Stillwater, OK, in September 2007 to determine the effects of clinical BRD observed during preconditioning on subsequent feedlot performance, carcass characteristics, and meat attributes. During a 63-d preconditioning period, morbidity and mortality attributed to BRD were 57.6 and 8.6%, respectively. Immediately after preconditioning, heifers were grouped according to health outcome category and allotted to finishing pens (5 to 7 heifers/pen). Heifers were never treated for BRD (0X; n = 9 pens), treated 1 time (1X; n = 9 pens), 2 times (2X; n = 6 pens), 3 times (3X; n = 6 pens), or designated as chronically ill (CI; n = 2 pens). Arrival BW was not different (P = 0.21) among treatment categories. However, disease incidence during preconditioning decreased (P < 0.001) growth, resulting in BW of 318, 305, 294, 273, and 243 kg for 0X, 1X, 2X, 3X, and CI, respectively, at the start of the finishing phase. Estimates on the LM, taken by ultrasound on d 65 and 122, were combined with BW and visual appraisal to target common average endpoint within category and block. On average, heifers were slaughtered on d 163 for 0X, 1X, and 2X, d 182 for 3X, and d 189 for CI (P < 0.01). Final BW was similar (P > or = 0.18) for heifers treated 0, 1, 2, or 3 times, but heifers deemed CI weighed less (P = 0.01) than 3X heifers. Considering the finishing phase only, ADG was linearly increased (P < 0.001) with increasing BRD treatments, but was linearly decreased (P = 0.003) as BRD treatments increased from arrival to slaughter. Therefore, G:F was greater (P = 0.007) for CI than 3X and linearly increased (P = 0.002) from 0X to 3X. Similar to BW, HCW was less (P = 0.03) for CI than 3X. Marbling score tended (P = 0.06) to decrease linearly as the number of treatments increased, but no other differences (P > or = 0.24) in carcass traits were detected. No differences were observed in beef tenderness (P = 0.65), and no consistent trends were noted in retail display or palatability data. Less than 20 additional days on feed were required for heifers treated 3 times to have similar BW and carcass characteristics to heifers never treated for BRD. Segregating animals with multiple BRD treatments and feeding them to an acceptable carcass endpoint may be a viable strategy for increasing value of animals treated for BRD.