Daily behavioral measures recorded by precision technology devices may indicate bovine respiratory disease status in preweaned dairy calves.

Precision technology devices can measure and detect relative changes in an animal's behavior to possibly create alerts to intervene and to administer treatments. However, the association of relative changes in daily feeding and activity behaviors in calves with bovine respiratory disease (BRD) status is still largely unexplored. The objective of this case-control study was to determine if daily behavioral patterns of preweaning dairy calves (measured by precision technologies) change before BRD diagnosis. This case-control study enrolled 33 pairs of calves (33 BRD calves matched by age, sex, and birthdate to 33 controls) health scored daily for BRD for the preweaning period (until 50 d on the automated feeder). A pedometer (IceQube, Ice Robotics) was attached to the left rear leg to track activity (lying time, lying bouts, total steps, and acceleration activity index). At 3.0 ± 2.0 d of age, calves were trained to use the automated feeder, which recorded milk and calf starter intake, drinking speed, and feeder visits. Calves were allotted a maximum 10 L/d of milk replacer (Cow's Match, Land O'Lakes Animal Milk Products Co.; 140 g/L) and starter (Special Calf Starter and Grower, Baghdad Feeds), ad libitum. Calves were scored daily for signs of BRD using the Wisconsin scoring system, and their lungs were scored with ultrasonography twice weekly. Outward signs of BRD as defined by the Wisconsin scoring system and an area of consolidated lung ≥3.0 cm2 was identified as BRD (d 0). Relative changes in daily behaviors were calculated using d -5 before BRD diagnosis as the baseline for each calf for each behavior. Linear mixed models were used to investigate the association of BRD status with feeding behaviors, activity, and relative changes in calf behavior over a 5-d period before diagnosis, as well as the BRD status × day interaction. Calves with a BRD bout were diagnosed at an average age of 33.0 ± 9.0 d (mean ± standard deviation) and weighed 56.1 ± 9.7 kg. Over the period, BRD calves had reduced milk and starter intake, greater lying times, and fewer lying bouts, step counts, and activity indices when compared with healthy calves. Furthermore, there was a BRD status × day interaction for relative changes in unrewarded visits, and relative changes in calf starter intake. Specifically, BRD calves had a decline in relative changes in their unrewarded visits on d -4, -2, -1, and 0 compared with healthy calves. This study suggests that there is the potential to use feeding and activity behaviors to identify BRD development in preweaning calves. However, utilization of an animals' daily behavioral patterns in real time is fundamental for developing disease detection algorithms, thus we suggest relative changes in unrewarded visits may be useful for algorithm development when d -5 is used as a baseline. Future research should investigate the potential of feeding behavior and activity levels collectively to indicate BRD status in calves using machine learning techniques.

Progression of nasopharyngeal and tracheal bacterial microbiotas of feedlot cattle during development of bovine respiratory disease.

It is generally accepted that as bovine respiratory disease (BRD) develops, bacterial pathogens first proliferate in the nasopharynx and then colonize the lungs, leading to bronchopneumonia. However, such temporal changes have never been definitively demonstrated. Therefore, the objective was to describe the progression of the nasopharyngeal and tracheal bacterial microbiotas of feedlot cattle during development of BRD. Nasopharyngeal swabs and tracheal wash samples were collected from 24 heifers over 20 d after arrival at a feedlot. Heifers were assessed daily and sampled based on reticulo-rumen/rectal temperatures and development of clinical signs of BRD. The study end point for each heifer was either at BRD treatment (BRD group; n = 15) or day 20 if the heifer remained healthy or did not meet BRD treatment criteria (TOL group; n = 9). Total DNA was extracted from each sample and the 16S rRNA gene (V3-V4) sequenced. Alpha and beta diversity were compared between BRD-TOL groups and sampling locations over time. There were no common patterns of change over time in composition or diversity of either the nasopharyngeal or tracheal bacterial microbiotas of cattle that developed BRD. Health status affected bacterial composition (R2 = 0.043; < 0.001), though this effect was low compared to variation among individual animals (R2 = 0.335; < 0.001) and effects of days on feed (R2 = 0.082; < 0.001). Specific bacterial taxa (Moraxella and Mycoplasma dispar) nevertheless appeared to have a potential role in respiratory health.

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.

Evaluation of a Computer-aided Lung Auscultation System for Diagnosis of Bovine Respiratory Disease in Feedlot Cattle.

BACKGROUND: A computer-aided lung auscultation (CALA) system was recently developed to diagnose bovine respiratory disease (BRD) in feedlot cattle. OBJECTIVES: To determine, in a case-control study, the level of agreement between CALA and veterinary lung auscultation and to evaluate the sensitivity (Se) and specificity (Sp) of CALA to diagnose BRD in feedlot cattle. ANIMALS: A total of 561 Angus cross-steers (initial body weight = 246 ± 45 kg) were observed during the first 50 day after entry to a feedlot. METHODS: Case-control study. Steers with visual signs of BRD identified by pen checkers were examined by a veterinarian, including lung auscultation using a conventional stethoscope and CALA that produced a lung score from 1 (normal) to 5 (chronic). For each steer examined for BRD, 1 apparently healthy steer was selected as control and similarly examined. Agreement between CALA and veterinary auscultation was assessed by kappa statistic. CALA's Se and Sp were estimated using Bayesian latent class analysis. RESULTS: Of the 561 steers, 35 were identified with visual signs of BRD and 35 were selected as controls. Comparison of veterinary auscultation and CALA (using a CALA score ≥2 as a cut off) revealed a substantial agreement (kappa = 0.77). Using latent class analysis, CALA had a relatively high Se (92.9%; 95% credible interval [CI] = 0.71-0.99) and Sp (89.6%; 95% CI = 0.64-0.99) for diagnosing BRD compared with pen checking. CONCLUSIONS: CALA had good diagnostic accuracy (albeit with a relatively wide CI). Its use in feedlots could increase the proportion of cattle accurately diagnosed with BRD.

Immunology of bovine respiratory syncytial virus in calves.

Bovine respiratory syncytial virus (BRSV) is an important cause of respiratory disease in young calves. The virus is genetically and antigenically closely related to human (H)RSV, which is a major cause of respiratory disease in young infants. As a natural pathogen of calves, BRSV infection recapitulates the pathogenesis of respiratory disease in man more faithfully than semi-permissive, animal models of HRSV infection. With the increasing availability of immunological reagents, the calf can be used to dissect the pathogenesis of and mechanisms of immunity to RSV infection, to analyse the ways in which the virus proteins interact with components of the innate response, and to evaluate RSV vaccine strategies. Passively transferred, neutralising bovine monoclonal antibodies, which recognise the same epitopes in the HRSV and BRSV fusion (F) protein, can protect calves against BRSV infection, and depletion of different T cells subsets in calves has highlighted the importance of CD8(+) T cells in viral clearance. Calves can be used to model maternal-antibody mediated suppression of RSV vaccine efficacy, and to increase understanding of the mechanisms responsible for RSV vaccine-enhanced respiratory disease.

The effect of respiratory disease and a preventative antibiotic treatment on growth, survival, age at first calving, and milk production of dairy heifers.

Bovine respiratory disease complex (BRD) is a common disease in weaned dairy calves that incurs economic and welfare costs. This study was an extension of a randomized clinical trial in which a single injection of tulathromycin (TUL) or oxytetracycline (TET) was administered at first movement to group housing for the prevention of BRD in the 60 d following antimicrobial treatment (BRD60). Calves treated with TUL were 0.5 times [95% confidence interval (CI): 0.4 to 0.7] as likely to be treated for BRD60 as calves treated with TET. The objectives of the current study were to evaluate the long-term effects of BRD and antibiotic treatment on growth of heifers until breeding age, age at first calving, incidence of dystocia, milk production, and mortality before first calving and mortality before 120 d in milk. At entry to the breeding barn (382 d of age), calves that experienced BRD60 weighed 16.0±2.3 kg less than calves that did not. Survival to first calving was recorded for 98% (1,343/1,392) of the heifers on this trial. For TET and TUL heifers with BRD60, 63% (94/150) and 73% (64/88) survived to first lactation, respectively. For TET and TUL calves without BRD60, 84% (436/517) and 84% (494/588) survived to first lactation, respectively. The median age at first calving for heifers with and without BRD60 was 714 (95% CI: 705-723) and 702 (95% CI: 699-705) days, respectively. Heifers with BRD60 were 1.5 (95% CI: 1.1-2.2) times more likely to have a calving ease score ≥2 at their first calving compared with heifers without BRD60. The administration of TUL at movement to group housing may have a role in the prevention of BRD and in mitigating some of the long-term effects of this disease.

Early detection of bovine respiratory disease in young bulls using reticulo-rumen temperature boluses.

The use of reticulo-rumen temperature boluses to detect bovine respiratory disease (BRD) was investigated in young bulls following their entry into a fattening unit. Twenty-four bulls received a bolus at entry and were observed for 40 days. As soon as a reticulo-rumen hyperthermia (RH) episode was detected using the bolus, clinical examination was performed by a veterinarian and then repeated every 12-24h until the end of RH episode. Fifty-two RH episodes were detected in 22 animals. High rectal temperatures (40.1±0.6°C) were observed during these episodes. BRD was diagnosed on the basis of clinical examination during 38/52 RH episodes in 21 animals (positive predictive value 73%). The onset of BRD signs always occurred after the onset of RH episodes, with a time-lag from 12 to 136 h, depending on BRD signs. Monitoring reticulo-rumen temperature permits early detection of BRD; however, clinical examination is required to confirm BRD.

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.

The effect of treatment with long-acting antibiotic at postweaning movement on respiratory disease and on growth in commercial dairy calves.

Bovine respiratory disease (BRD) is a major concern when raising replacement heifers because of the high incidence and long-term effects of this disease, such as decreased growth and increased time to first calving. The objective of this study was to determine the effect of tulathromycin (TUL) treatment at postweaning movement on the incidence of BRD in dairy replacement heifers. A total of 1,395 heifers were enrolled between November 2006 and June 2007 at a commercial heifer-raising facility. Calves were randomly assigned either to treatment with TUL or to a positive control group treated with oxytetracycline (TET). Calves treated with TUL were 0.5 times (95% CI: 0.4 to 0.7) less likely to be treated for BRD in the 60 d following enrollment than calves treated with TET. For calves that had no history of BRD in the pre-enrollment period, TET calves weighed 4.9+/-0.5kg less than TUL calves after 6 wk in group housing. If calves were treated for BRD in the pre-enrollment period, there was no treatment effect on growth. Calves with clinical BRD in the 60 d following movement weighed 7.9+/-0.6kg less than calves without BRD after 6 wk in group housing. Treatment with TUL at the time of movement to group housing had a beneficial effect on the health and performance through the prevention of BRD in dairy calves with no prior history of the disease. Moreover, BRD after movement to group housing after weaning had a significant effect on the growth of dairy calves.

Evaluation of fixed sources of variation and estimation of genetic parameters for incidence of bovine respiratory disease in preweaned calves and feedlot cattle.

The primary objective of this study was to estimate variance components and heritability of bovine respiratory disease (BRD) incidence in beef calves before weaning and during the finishing phase. The second objective was to investigate the impact of BRD incidence and treatment frequency on performance and carcass traits. Bovine respiratory disease is the biggest and most costly health challenge facing the cattle industry. The 2 populations used consisted of 1,519 preweaned calves and 3,277 head of feedlot cattle. The incidence rate of BRD in preweaned calves was 11.39%, and among treated cattle, 82.1% were treated once, 13.9% were treated twice, and 4.0% were treated 3 times or more. The incidence of BRD (P = 0.35) and the number of treatments (P = 0.77) had no significant effect on weaning BW. Heritability estimates of the entire preweaned population for BRD resistance and number of treatments were 0.11 +/- 0.06 and 0.08 +/- 0.05, respectively. The genetic correlation estimates for BRD incidence with weaning BW and birth BW were low (-0.02 +/- 0.32 and 0.07 +/- 0.27, respectively). The same estimate for the number of BRD treatments with weaning BW and birth BW was 0.25 +/- 0.35 and 0.30 +/- 0.27, respectively. The observed BRD incidence rate for feedlot cattle was observed at 9.43%. Incidence of BRD significantly (P < 0.01) decreased overall and acclimation ADG by 0.06 +/- 0.01 kg/d and 0.28 +/- 0.03 kg/d, respectively. Carcass traits were also significantly (P < 0.05) affected by BRD incidence; untreated cattle had a 9.1 +/- 1.7-kg heavier HCW. Results were similar in the analysis of treatment frequency. The heritability estimate of BRD incidence and the number of treatments were 0.07 +/- 0.04 and 0.02 +/- 0.03, respectively. Estimates of genetic correlations of BRD incidence with production traits were -0.63 +/- 0.22 for acclimation ADG, -0.04 +/- 0.23 for on-test ADG, -0.31 +/- 0.21 for overall ADG, -0.39 +/- 0.21 for final BW, -0.22 +/- 0.22 for HCW, -0.03 +/- 0.22 for LM area, 0.24 +/- 0.25 for fat, and -0.43 +/- 0.20 for marbling score. Similar results for the number of treatments and production traits were -1.00 +/- 0.68 for acclimation ADG, -0.04 +/- 0.39 for on-test ADG, -0.47 +/- 0.41 for overall ADG, -0.66 +/- 0.40 for final BW, -0.58 +/- 0.45 for HCW, -0.12 +/- 0.38 for LM area, 0.42 +/- 0.50 for fat, and -0.32 +/- 0.37 for marbling score. Because of the high economic cost associated with BRD incidence, even these modest estimates for heritability of BRD resistance should be considered for incorporation into beef cattle breeding programs.

Biomarkers for prediction of bovine respiratory disease outcome.

Fatal bovine respiratory disease (BRD) is frequently the result of a primary viral and a secondary bacterial respiratory infection. In cattle, BRD causes more than half of feedlot deaths and has a major impact on financial losses in the cattle industry in North America. It is, therefore, very important to understand the mechanism of this complex disease process as well to predict and identify BRD susceptible cattle to enhance treatment efficacy. We recently established the value of using combinatorial omics approaches to identify candidate biomarkers associated with stress responses, a factor that can increase the severity of BRD. The objective of the present investigation was to experimentally recreate fatal BRD and to use a combinatorial analysis of proteomic, metabonomic, and elemental profiles in serum samples to determine if multimethod analysis of these biomarkers could predict disease outcome. The proteomic studies revealed that changes in the serum proteome were significant on day 4 postviral infection when compared to preinfection (day 0) serum samples. Proteomic studies identified a group of acute phase proteins (haptoglobin and apolipoprotein AI), which could be linked to a primary viral respiratory infection, but there was no significant association observed with fatal BRD. In contrast, metabonomic and elemental analyses identified candidate biomarkers for viral infection (glucose, LDL, valine, phosphorous, and iron) and disease outcome (lactate, glucose, iron). While multivariate analysis of proteomic and metabolite profiles did not discriminate between animals that survived or died postsynergic viral-bacterial infection by analyzing preinfection (day 0) serum samples, analysis of serum elemental profiles prior to infection was, however, predictive of BRD outcome. Furthermore, discriminant analyses of all three methodologies used to profile serum (collected on day 4 postviral but prior to bacterial infection) revealed differential trends between animals that survived or died following synergic viral-bacterial infection. Thus, a combinatorial approach using proteomic, metabonomic, and elemental analyses of serum samples revealed that multimethod analysis could discriminate between the complex biological responses to secondary bacterial respiratory infection and predict disease outcome.

Plasma metabolites of receiving heifers and the relationship between apparent bovine respiratory disease, body weight gain, and carcass characteristics.

Six hundred sixty-five crossbred beef heifers initially weighing 225 kg were used in a completely randomized design to measure plasma glucose, lactate, and urea N concentrations at time of initial processing, determine the incidence of apparent bovine respiratory disease (BRD) in receiving cattle, and evaluate the effect of apparent BRD on subsequent cattle growth and carcass characteristics. Heifers were processed within 24 h of arrival, and processing included vaccination against common viral and clostridial diseases, recording rectal temperature, and sampling whole blood for subsequent measurement of plasma glucose, lactate, and urea concentrations. Heifers were monitored for clinical signs of apparent BRD, including depression, lethargy, anorexia, coughing, rapid breathing, and nasal or ocular discharge. Heifers exhibiting signs of apparent BRD received antibiotic therapy, and the number of times a heifer was treated for apparent BRD was recorded. Following the 36-d receiving period, heifers were transported to native grass pastures and allowed to graze for 136 d. At the end of the grazing season, heifers were transported to a commercial feedlot where they were adapted to a common finishing diet offered for ad libitum consumption. Following the 124-d finishing period, heifers were slaughtered and carcass data were collected. Heifers treated for apparent BRD had decreased plasma glucose (linear, P < 0.01), lactate (linear, P < 0.01), and urea N concentrations (linear, P < 0.06) measured at time of initial processing. Rectal temperature measured at time of initial processing tended to be greater (linear, P < 0.11) for heifers treated for apparent BRD. Heifers treated for apparent BRD during the receiving period had decreased overall ADG (linear, P < 0.10), final BW (linear, P < 0.01), HCW (linear, P < 0.01), fat thickness (linear, P < 0.01), and marbling score (linear, P < 0.03). These data suggest that initial plasma glucose and lactate concentrations might be affected by the health status of receiving cattle and that increased incidence of apparent BRD in cattle decreases ADG and carcass quality.

Effects of commingling beef calves from different sources and weaning protocols during a forty-two-day receiving period on performance and bovine respiratory disease.

The study objective was to determine health and performance of ranch calves from different preconditioning strategies during a 42-d receiving period when commingled with calves of unknown health histories from multiple sources. Steer calves from a single source ranch (RANCH) were weaned and immediately shipped to a feedlot (WEAN, initial BW = 247 +/- 29 kg); weaned on the ranch for 45 d before shipping, but did not receive any vaccinations (WEAN45, initial BW = 231 +/- 26 kg); or weaned, vaccinated with modified live viral vaccine, and held on the ranch for 45 d before shipping (WEANVAC45, initial BW = 274 +/- 21 kg). Multiple-source steers were purchased through auction markets (MARKET, initial BW = 238 +/- 13 kg), and upon receiving, a portion of ranch-origin steers from each weaning group was commingled with a portion of MARKET cattle (COMM). The experimental design was completely randomized with a 2 x 3 +1 factorial arrangement of treatments. Factors were RANCH vs. COMM and weaning management (WEAN vs. WEAN45 vs. WEANVAC45) as the factors; MARKET cattle served as the control. Calves of WEAN, WEAN45, and MARKET were vaccinated on arrival at the feedlot. Ranch-origin calves tended (P = 0.06) to have greater ADG than COMM or MARKET calves, although ADG was not affected (P = 0.46) by weaning management. Across the 42-d receiving period, DMI was not affected (P = 0.85) by cattle origin. However, MARKET, WEAN45, and WEANVAC45 calves consumed more (P < 0.001) DM than WEAN calves. Gain efficiency was not affected (P > or = 0.11) by treatment. Ranch-origin calves were less (P < 0.001) likely to be treated for bovine respiratory disease than MARKET calves; COMM calves were intermediate. Calves that were retained on the ranch after weaning (WEAN45 and WEANVAC45) were also less likely to be treated (P = 0.001) than MARKET or WEAN calves. As expected, differences in morbidity related to differences in health costs. Calves of WEAN45 and WEANVAC45 had less (P < 0.001) health costs than MARKET and WEAN calves. On arrival, serum haptoglobin concentrations were greater (P < 0.001) in MARKET and WEAN compared with WEAN45 and WEANVAC45 calves. Calves from a single source that are retained on the ranch for 45 d after weaning exhibit less morbidity and less health costs during the receiving period at the feedyard than when cattle are commingled or trucked to the feedyard immediately after weaning.

Bovine respiratory disease in feedlot cattle: phenotypic, environmental, and genetic correlations with growth, carcass, and longissimus muscle palatability traits.

Bovine respiratory disease (BRD) is the most costly feedlot disease in the United States. Selection for disease resistance is one of several possible interventions to prevent or reduce the economic loss associated with animal disease and to improve animal welfare. Undesirable genetic relationships, however, may exist between production and disease resistance traits. The objectives of this study were to estimate the phenotypic, environmental, and genetic correlations of BRD with growth, carcass, and LM palatability traits. Health records on 18,112 feedlot cattle over a 15-yr period and slaughter data on 1,627 steers over a 4-yr period were analyzed with bivariate animal models. Traits included ADG, adjusted carcass fat thickness at the 12th rib, marbling score, LM area, weight of retail cuts, weight of fat trim, bone weight, Warner-Bratzler shear force, tenderness score, and juiciness score. The estimated heritability of BRD incidence was 0.08 +/- 0.01. Phenotypic, environmental, and genetic correlations of the observed traits with BRD ranged from -0.35 to 0.40, -0.36 to 0.55, and -0.42 to 0.20, respectively. Most correlations were low or negligible. The percentage of carcass bone had moderate genetic, phenotypic, and environmental correlations with BRD (-0.42, -0.35, and -0.36, respectively). Hot carcass weight and weight of retail cuts had moderate, undesirable phenotypic correlations with BRD (0.37 and 0.40, respectively). Correlations of BRD with LM palatability and ADG were not detected. Low or near zero estimates of genetic correlations infer that selection to reduce BRD in feedlot cattle would have negligible correlated responses on growth, carcass, and meat palatability traits or that selection for those traits will have little effect on BRD susceptibility or resistance.