Bovine Respiratory Disease Morbidity Research Articles

Bovine respiratory disease (BRD) in postweaning calves with different prevention strategies and the impact on performance and health status

Bovine respiratory disease (BRD) is one of the most common causes of morbidity and mortality in bovine calves, especially around the weaning period, when the calves are usually moved from individual to group housing. BRD has negative perfor­mance and economic consequences that extend well beyond the actual event. Therefore, we aimed to compare BRD morbid­ity, mortality and growth in dairy and dairy beef cross-bred calves during the first commingle groups using 2 different BRD prevention strategies. We hypothesized that one or both pre­vention strategies would reduce BRD morbidity and mortality, resulting in better health status and performance in calves.

175 Effects of Random Metaphylaxis Administered at Feedlot Arrival to 0, 33, 66, Or 100% of High-Risk Beef Cattle on Health Outcomes, Complete Blood Count, and Growth Performance

Abstract Our objective was to evaluate the effects of random metaphylaxis administered on arrival to 0, 33, 66, or 100% of high-risk beef cattle on clinical health, growth performance, and complete blood cell counts during a 35-d receiving period. Crossbred beef steers (n = 216; arrival BW = 197 ± 6.4 kg) were used in a generalized complete block design consisting of 2 source blocks and 4 treatments. Experimental treatments and steers were randomly assigned to pen within source block: 1) negative control, subcutaneous injection with sterile saline (NCON); 2) 33% of steers/pen given metaphylaxis (33M); 3) 66% of steers/pen given metaphylaxis (66M); and 4) positive control; conventional metaphylaxis given to 100% of steers (CONV). Body weight and blood samples for quantification of complete blood count were collected on d 0, 14, and 35. Pen was considered the experimental unit for all analyses. Continuous data were analyzed using PROC MIXED, and categorical data were analyzed as binomial proportions using PROC GLIMMIX. Treatment was included in the model as a fixed effect and source block was a random effect. Complete blood counts were analyzed as repeated measures, where day was the repeated effect and pen within treatment was the subject. The percentage of steers treated with an antibiotic for bovine respiratory disease (BRD) once was greater (P < 0.01) for NCON and 33M than for 66M and CONV. Neither BW on d 35 nor average daily gain from d 0 to 35 differed among treatments (P > 0.65), but dry matter intake (DMI) and DMI as a percentage of BW from d 0 to 35 was greater (P < 0.03) for 66M and CONV than for NCON and 33M. No differences in hematological variables were detected among treatments (P > 0.19), whereas all complete blood count variables were affected by day (P < 0.01), except for mean corpuscular hemoglobin concentration (P = 0.81). Most notably, the neutrophil:lymphocyte ratio was greater (P < 0.01) on d 0 than on d 14 and 35. These data suggest that arrival metaphylaxis can be administered to 66% of cattle at random without increasing BRD morbidity while simultaneously increasing DMI similar to conventional metaphylaxis. Random metaphylaxis may be a viable method to decrease antibiotic use in the feedlot industry, while maintaining health outcomes and growth performance of high-risk beef cattle.

Evaluating the timing of bovine respiratory disease morbidity and mortality in feedlot cattle by first treatment, fatal disease onset, and days from first treatment to death

Little research has evaluated risk factors influencing the timing of bovine respiratory disease (BRD); the main focus of previ­ous BRD research has been on environmental and demographic factors influencing disease frequency. The study objective was to descriptively evaluate typical BRD temporal patterns for cat­tle in U.S. Great Plains feedyard systems.

An Evaluation of Temporal Distributions of High, Low, and Zero Cohort Morbidity of Cumulative First Treatment Bovine Respiratory Disease and Their Associations with Demographic, Health, and Performance Outcomes in US Feedlot Cattle.

Timing and magnitude of bovine respiratory disease (BRD) can impact intervention and overall economics of cattle on feed. Furthermore, there is a need to better describe when cattle are being treated for BRD. The first objective was to perform a cluster analysis on the temporal distributions of cumulative first treatment BRD from HIGH (≥15% of cattle received treated for BRD) and LOW cohorts (>0 and <15% of cattle received treated for BRD) to assess cohort-level timing (days on feed) of BRD first treatments. The second objective was to determine associations among cluster groups (temporal patterns) and demographic risk factors, health outcomes, and performance. Cluster analysis determined that optimal number of clustering groups for the HIGH morbidity cohort was six clusters and LOW morbidity cohort was seven clusters. Cohorts with zero BRD treatment records were added for statistical comparisons. Total death loss, BRD morbidity, average daily gain (ADG), railing rate, days to 50% BRD, cattle received, shrink, arrival weight, and sex were associated with temporal groups (p < 0.05). These data could be used as a tool for earlier identification and potential interventions for cohorts based on the BRD temporal pattern.

Comprehensive Outcomes Affected by Antimicrobial Metaphylaxis of Feedlot Calves at Medium-Risk for Bovine Respiratory Disease from a Randomized Controlled Trial

The objectives were to evaluate the effects of metaphylaxis (META) and pull-and-treat (PT) programs on health, antimicrobial use, beef production, economics, and greenhouse gas emissions in cattle at medium risk for bovine respiratory disease (BRD). A randomized complete block design was used at two US commercial feedlots. Steers and heifers [2366 total; 261 (±11.0) kg initial weight] were blocked by sex and feedlot arrival, and allocated to one of two pens within a block (16 pens total, eight blocks). Pens were randomly assigned to treatment: META, tulathromycin injection at initial processing; or PT, tulathromycin injection only for first clinical BRD treatment. Data were analyzed with linear and generalized linear mixed models. There was greater BRD morbidity in PT than META cattle (17.2% vs. 7.3% respectively; p < 0.01), and greater total mortality (2.5% vs. 1.1% respectively; p = 0.03). Per animal enrolled, 1.1 antimicrobial doses were used for META compared to 0.2 for PT (p < 0.01). Per animal enrolled, final live (p = 0.04) and carcass (p = 0.08) weights were greater for META than PT; however, net returns ($/animal) were not significantly different (p = 0.71). Compared to PT, total lifetime estimated CO2 equivalent emissions from production were reduced by 2% per unit of live weight for META (p = 0.09). While antimicrobial use was reduced with PT, there may be substantial negative impacts on other outcomes if META was not used in this type of cattle population.

Effects of injectable vitamin E before or after transit on receiving phase growth performance, health, and blood parameters of beef steers.

The objective was to determine the effects of injectable vitamin E (VE) before or after transit on feedlot cattle receiving performance, health, and blood parameters. Angus × Simmental steers (n = 196; body weight [BW] = 163 ± 29 kg) were utilized in a randomized complete block design. Steers were blocked by BW and randomly assigned to 1 of 3 treatments: intramuscular injections of saline pre- and post-transit (CON), intramuscular injections of VE (2,000 mg d-α-tocopherol) pre-transit and saline post-transit (PRE), or intramuscular injections of saline pre-transit and VE (2,000 mg d-α-tocopherol) post-transit (POST). Pre-transit injections were administered on day 0, and steers were transported on day 7 for approximately 4 h (348 km). After arrival, steers were fed a common corn silage-based diet in GrowSafe bunks. Final BW tended to be greater (P = 0.08) for CON steers compared with POST steers while PRE steers were intermediate. From days 7 to 63, treatment affected average daily gain (ADG) with PRE and CON steers exhibiting (P = 0.04) greater ADG compared with POST steers. Dry matter intake (DMI), water intake, and gain to feed from days 7 to 63 were not affected (P ≥ 0.17) by treatment. Day 0 serum α-tocopherol concentrations were considered marginal (2.3 ± 0.2 mg/l). A treatment × day interaction (P < 0.01) was observed for serum α-tocopherol concentrations. Serum α-tocopherol concentrations were greatest for PRE steers on day 7 (prior to and post-transit), but greater for POST steers on dys 10 and 14. Plasma ferric-reducing antioxidant potential concentrations increased (P = 0.04) for POST steers compared with CON steers and PRE steers being intermediate. Plasma non-esterified fatty acids (NEFA) concentrations exhibited a treatment × day interaction (P = 0.04) with CON and POST steers being 16% and 14% greater than PRE steers on day 14, respectively. On day 21, NEFA concentrations were greatest for POST steers compared with PRE steers and CON steers being intermediate. There was no main effect (P ≥ 0.14) of treatment on the number of bovine respiratory disease morbidity treatments. Hair cortisol concentrations were decreased (P < 0.01) 14 days after transit for PRE and POST steers compared with CON steers. Overall, injectable VE administered before or after transit increased serum tocopherol concentrations while reducing stress, but did not improve the growth performance of beef steers during the receiving phase.

Tulathromycin metaphylaxis increases nasopharyngeal isolation of multidrug resistant Mannheimia haemolytica in stocker heifers.

Bovine respiratory disease (BRD) is a leading cause of disease in feedlot and stocker calves with Mannheimia haemolytica (MH) as one of the most common etiologies. One of the most effective means of controlling BRD is through metaphylaxis, which involves administering antimicrobials to all animals at high risk of developing BRD. However, increasing prevalence of multidrug resistant (MDR) MH may reduce efficacy of metaphylaxis due to decreased susceptibility to drugs used for metaphylaxis. Primarily, this study aimed to determine the effect of tulathromycin metaphylaxis and subsequent BRD treatment on antimicrobial resistance (AMR) in MH isolated from stocker calves. Secondary objectives included evaluating the effect of metaphylaxis and treatment for BRD on animal health and comparing the genetic relationship of MH isolated. Crossbred beef heifers (n = 331, mean weight = 232, SD = 17.8 kg) at high risk for BRD were randomly assigned to receive tulathromycin metaphylaxis (META, n = 167) or not (NO META, n = 164). Nasopharyngeal swabs were collected for MH isolation, antimicrobial susceptibility testing and whole genome sequencing at arrival and 3 (WK3) and 10 (WK10) weeks later. Mixed-effects logistic regression was used to identify risk factors for isolation of MH and MDR MH (resistant to ≥3 antimicrobial drug classes) at 3 and 10 weeks, BRD morbidity, and crude mortality. Animals in the META group had higher odds of isolation of MDR MH at 3 weeks [OR (95% CI) = 13.08 (5-30.9), p < 0.0001] and 10 weeks [OR (95% CI) = 5.92 (1.34-26.14), p = 0.019] after arrival. There was no difference in risk of isolation of any MH (resistant or susceptible) between META and NO META groups at all timepoints. Animals in the NO META group had 3 times higher odds of being treated for BRD [WK3: OR (95% CI) = 3.07 (1.70-5.52), p = 0.0002; WK10: OR (95% CI) = 2.76 (1.59-4.80), p = 0.0002]. Antimicrobial resistance genes found within isolates were associated with integrative conjugative element (ICE) genes. Tulathromycin metaphylaxis increased risk of isolation of MDR MH and in this population, the increase in MDR MH appeared to be associated with ICE containing antimicrobial resistance genes for multiple antimicrobial classes. This may have important implications for future efficacy of antimicrobials for control and treatment of BRD.

Impact of Water Sources and Shared Fence Lines on Bovine Respiratory Disease Incidence in the First 45 Days on Feed.

Bovine respiratory disease (BRD) is a frequent disease in feedlot cattle, but little is known on the role of pen housing conditions. The objective of this research is to use a retrospective analysis with data from 10 U.S. feedlots to determine potential associations between BRD risk during the first 45 days after arrival with pen-level management factors including the number of water sources, shared water sources, and shared fence lines. Generalized linear mixed models were used to evaluate associations between management factors, cattle demographics, and BRD incidence. The effect of shared water sources on BRD risk was modified by arrival weight and cohort size (p &lt; 0.05). Cattle with two water sources had lower BRD morbidity (5.55% ± 0.98) compared to cattle with one water source (8.80% ± 1.50) when arrival weight was 227 kg to 272 kg, while there were few differences in heavier weight cattle. Cattle with two water sources had lower BRD morbidity (3.11% ± 0.56) compared to one water (5.50% ± 0.10) when cohort size was 100-175 head, but there were no BRD morbidity differences when bigger or smaller cohorts were evaluated. Shared fence lines and water sources were associated with BRD risk; however, no biologically meaningful results were identified. The number of water sources was associated with BRD risk, and effects were modified by cohort size and arrival weight.

13 Supplemental Trace Minerals as Amino Acid Complexed or Inorganic Sources for Beef Cattle During the Receiving Period

Abstract To investigate the effects of inorganic or amino acid-complexed sources of trace minerals (zinc, copper, manganese, and cobalt) on performance and morbidity of beef heifers during the receiving period, crossbred beef heifer calves (n = 287, initial body weight = 231 kg) arriving on 3 delivery dates were used in a 42-day receiving trial. Heifers were processed after arrival and stratified by day -1 body weights and allocated randomly to 8 pens (11 to 13 heifers/pen; total of 24 pens). Within truckload, pens were assigned randomly to dietary treatment (12 pens/treatment). Calves were housed on 0.42-ha grass paddocks, provided ad libitum access to bermudagrass hay and water, and fed grain supplements that served as the carriers of the dietary treatments. Treatments consisted of supplemental zinc (360 mg/d), copper (125 mg/d), manganese (200 mg/d), and cobalt (12 mg/d) from complexed (Availa 4, Zinpro Corporation, Eden Prairie, MN) or inorganic sources (sulfates). Cattle were observed daily for clinical bovine respiratory disease (BRD). If presenting symptoms of BRD and if rectal temperature was ≥ 40°C, cattle were deemed morbid and treated with an antibiotic according to a standard preplanned protocol. Six heifers/pen were bled to determine serum haptoglobin concentrations on days 0, 14, and 28. Statistical analyses were performed using the MIXED and GLIMMIX procedures of SAS 9.4 with truckload as a random effect and pen within truckload specified as subject. There tended to be a treatment by day interaction for body weights (P = 0.07). Body weights did not differ on day 0 (P = 0.82) and day 14 (P = 0.36), but heifers supplemented with complexed trace mineral sources had greater body weights on day 28 (P = 0.04) and day 42 (P = 0.05; 264 vs. 260 kg, SE = 1.8). Overall average daily gains were greater for heifers supplemented with the complexed trace mineral sources (P = 0.05; 0.78 vs. 0.70 kg, SE = 0.03). Cattle supplemented with inorganic trace mineral sources had greater BRD morbidity incidence than cattle supplemented with complexed trace mineral sources (P = 0.03; 58 vs. 46%, SE = 3.6). Medication costs were lower for heifers supplemented with complexed trace mineral sources (P = 0.05; $11.01 vs. $14.90, SE = 1.33). Haptoglobin concentrations decreased throughout the trial (day, P &amp;lt; 0.001), and cattle supplemented with complexed trace mineral sources tended to have lower haptoglobin concentrations (P = 0.07). In conclusion, supplementing cattle for the first 42 days after arrival with amino acid complexed trace mineral sources improved heifer performance as compared to heifers supplemented with inorganic trace minerals.

Impact of preweaning vaccination on host gene expression and antibody titers in healthy beef calves.

The impact of preweaning vaccination for bovine respiratory viruses on cattle health and subsequent bovine respiratory disease morbidity has been widely studied yet questions remain regarding the impact of these vaccines on host response and gene expression. Six randomly selected calves were vaccinated twice preweaning (T1 and T3) with a modified live vaccine for respiratory pathogens and 6 randomly selected calves were left unvaccinated. Whole blood samples were taken at first vaccination (T1), seven days later (T2), at revaccination and castration (T3), and at weaning (T4), and utilized for RNA isolation and sequencing. Serum from T3 and T4 was analyzed for antibodies to BRSV, BVDV1a, and BHV1. Sequenced RNA for all 48 samples was bioinformatically processed with a HISAT2/StringTie pipeline, utilizing reference guided assembly with the ARS-UCD1.2 bovine genome. Differentially expressed genes were identified through analyzing the impact of time across all calves, influence of vaccination across treatment groups at each timepoint, and the interaction of time and vaccination. Calves, regardless of vaccine administration, demonstrated an increase in gene expression over time related to specialized proresolving mediator production, lipid metabolism, and stimulation of immunoregulatory T-cells. Vaccination was associated with gene expression related to natural killer cell activity and helper T-cell differentiation, enriching for an upregulation in Th17-related gene expression, and downregulated genes involved in complement system activity and coagulation mechanisms. Type-1 interferon production was unaffected by the influence of vaccination nor time. To our knowledge, this is the first study to evaluate mechanisms of vaccination and development in healthy calves through RNA sequencing analysis.

337 Effects of Dietary Supplementation of Saccharomyces Cerevisiae-Based Microbial Additive Containing Fermentation Products on Health, and Performance of Weaned Beef Steers During a 35-d Receiving Period

Abstract We examined the effects of dietary supplementation of Saccharomyces cerevisiae-based microbial additive containing fermentation products of multiple micro-organisms on health and performance of newly weaned beef steers during a 35-d receiving period. Crossbred beef steers (n = 80; 12-hour post-weaning; 206 ± 12 kg of BW) were stratified by BW into 4 pens (20 steers per pen) such that each pen had similar BW at the beginning of the experiment. The steers were assigned to receive a corn silage-based diet with no additive (CON; 2 pens) or a diet supplemented with a blend of live S. cerevisiae and the fermentation products of S. cerevisiae, Enterococcus lactis, Bacillus licheniformis, and B. subtilis at an average of 28 g/steer/d for the first 21 d (SYNB; 2 pens). Percentage of steers treated for bovine respiratory disease (BRD) was calculated for each dietary treatment. Daily DMI and weekly body weights were measured. Blood samples collected weekly were analyzed for mRNA expression of 84 immune-related genes and plasma metabolome. Compared with CON, supplemental SYNB increased (P ≤ 0.05) average daily gain (ADG) and DMI during the first 7 d. During the first 21 d, there was no treatment effect (P &amp;gt; 0.05) on final BW, DMI, and ADG. Over the entire 35-d receiving period, beef steers fed supplemental SYNB had greater (P = 0.01) ADG and had reduced percentage (35 vs. 50%) of animals treated for BRD. Whole blood expression of pro-inflammatory genes was downregulated while that of anti-inflammatory genes was upregulated in beef steers fed supplemental SYNB. Six nutrient metabolic pathways of great health benefits were enriched (FDR ≤ 0.05) in beef steers fed supplemental SYNB. This study demonstrated that dietary supplementation of SYNB during the first 21 d of arrival reduced BRD morbidity, improved the performance, immune, and metabolic status of beef steers over a 35-d receiving period.

Risk factors for mid- and late-feeding-stage bovine respiratory morbidity and mortality based on individual animal treatments of beef feedlot cattle

Previously published research on bovine respiratory disease (BRD) has emphasized the initial portion of the feeding phase; yet, little work has investigated risk factors associated with BRD incidence later in the feeding period. Our study objective was to identify risk factors associated with BRD morbidity and mortality timing within the feeding phase. Individual animal records for first BRD treatment (n = 188,437) or BRD mortality (n = 13,991) were classified as early stage, middle stage, or late stage based on the percentage of their cohorts’ feeding phase that was complete at day of event (event days on feed/cohort total days on feed). There were 141,097 early stage, 33,871 middle stage, and 13,469 late stage at first treatments for BRD and 7,821 early stage, 3,625 middle stage, and 2,545 late stage at death. Two ordinal logistic regression models (morbidity, mortality) were used to evaluate the association of cattle demographic factors (arrival weight, arrival lot size, sex, metaphylaxis, quarter of arrival) and the probability of an individual animal first treatment for BRD or mortality from BRD being early, middle, or late stage. All 2-way interactions of cattle demographics for morbidity were significant (P < 0.05), whereas for mortality, main effects of arrival weight and metaphylaxis were significant (P < 0.05) and only the 2-way interactions of sex by quarter of arrival and sex by lot size were significant (P < 0.05). In general, heifers, heavier animals at arrival, and cattle that arrived at the yard in the first and second quarter were the most likely demographic categories to have an initial diagnosis of BRD in the mid or late stage of the feeding phase.

Mycoplasma bovis is associated with Mannheimia haemolytica during acute bovine respiratory disease in feedlot cattle.

Bovine Respiratory Disease (BRD) represents a significant burden to the health of feedlot cattle and the profitability of the beef industry in the US. Mannheimia haemolytica is widely regarded as the primary bacterial pathogen driving acute BRD. While Mycoplasma bovis is most commonly implicated in chronic cases of BRD, this agent's potential role in acute stages of BRD is unclear. Therefore, this study aimed to evaluate potential associations between M. bovis and M. haemolytica during acute BRD in feedlot cattle. Nasal swabs (n = 1,044) were collected over time from feedlot cattle (n = 270) enrolled in an experiment assessing the effect of vaccination for Bovine Respiratory Syncytial Virus (BRSV). Swabs were analyzed for detection of M. bovis, M. haemolytica, Pasteurella multocida, Histophilus somni, and BRSV via multiplex qPCR assays. Data were analyzed using inverse conditional probability weighted (ICPW) logistic regression models to investigate potential effects of M. bovis presence on arrival (d0), day seven (d7) and day 14 (d14) post-arrival on M. haemolytica prevalence on day 28 (d28) post-arrival, adjusting for the previous history of P. multocida, H. somni, BRSV, BRD morbidity, and body weight. The potential association between time-to-BRD detection and M. bovis presence on d0, d7, and d14 post-arrival, was inferred via an ICPW time-to-event model. The presence of M. bovis in nasal swabs collected on d7 post-arrival was significantly associated with an increase in the prevalence of M. haemolytica on d28 (prevalence difference: 45%; 95% Confidence Interval: 31%, 60%; P-value < 0.001). Significant time-varying coefficients for M. bovis presence were detected at d0, d7, and d14 post-arrival in the ICPW time-to-event model (P-value < 0.001). The shortest median time-to-BRD detection was 29 days in cattle that were M. bovis positive on d0, d7, and d14 post-arrival and in those that were positive on d0 and d14 post-arrival. Under the conditions of this study, our findings suggest that M. bovis may be influencing the respiratory environment during the acute phase of BRD, increasing the abundance of M. haemolytica, which could have important impacts on the occurrence of BRD.

Determining relevant risk factors associated with mid- and late-feeding-stage bovine respiratory disease morbidity in cohorts of beef feedlot cattle

Previous bovine respiratory disease (BRD) research has focused on events early in the feeding phase, but the objective of this study was to determine characteristics and risk factors associated with cohort-level BRD morbidity in the middle and late portions of the feeding phase.

Comparing delayed versus on-arrival administration of a modified live viral vaccine in feedlot cattle

PICO question&#x0D; In auction market calves at high risk of developing bovine respiratory disease (BRD), does delayed (14–30 days) vaccination with a modified live vaccine (MLV) for viral respiratory pathogens versus administration of MLV on-arrival (within 24 hours of arrival) to the feedlot, result in a decreased percentage of calves with BRD morbidity diagnosed based on visual signs and rectal temperature &gt;40 degrees Celsius?&#x0D; &#x0D; Clinical bottom line&#x0D; Category of research question&#x0D; Treatment&#x0D; The number and type of study designs reviewed&#x0D; Two papers were critically reviewed. Both are randomised complete block designs&#x0D; Strength of evidence&#x0D; Weak&#x0D; Outcomes reported&#x0D; Delaying administration of a modified live respiratory vaccine to feedlot cattle may result in lower BRD retreatments&#x0D; Conclusion&#x0D; In feedlot calves, delaying modified live vaccine administration for viral respiratory pathogens may result in lower BRD retreatment rates than cattle receiving the vaccine on arrival to the feedlot. Significant statistical data from one study supported this conclusion while another showed numerically less retreatments in calves vaccinated on arrival versus delayed vaccination&#x0D; &#x0D; How to apply this evidence in practice&#x0D; The application of evidence into practice should take into account multiple factors, not limited to: individual clinical expertise, patient’s circumstances and owners’ values, country, location or clinic where you work, the individual case in front of you, the availability of therapies and resources.&#x0D; Knowledge Summaries are a resource to help reinforce or inform decision making. They do not override the responsibility or judgement of the practitioner to do what is best for the animal in their care.&#x0D; &#x0D;

Predicting Bovine Respiratory Disease Risk in Feedlot Cattle in the First 45 Days Post Arrival.

Bovine respiratory disease (BRD) is the leading cause of morbidity in feedlot cattle. The ability to accurately identify the expected BRD risk of cattle would allow managers to detect high-risk animals more frequently. Five classification models were built and evaluated towards predicting the expected BRD risk (high/low) of feedlot cattle within the first 45 days on feed (DOF) and incorporate an economic analysis to determine the potential health cost advantage when using a predictive model compared with standard methods. Retrospective data from 10 U.S. feedlots containing 1733 cohorts representing 188,188 cattle with known health outcomes were classified into high- (≥15% BRD morbidity) or low- (<15%) BRD risk in the first 45 DOF. Area under the curve was calculated from the test dataset for each model and ranged from 0.682 to 0.789. The economic performance for each model was dependent on the true proportion of high-risk cohorts in the population. The decision tree model displayed a greater potential economic advantage compared with standard procedures when the proportion of high-risk cohorts was ≤45%. Results illustrate that predictive models may be useful at delineating cattle as high or low risk for disease and may provide economic value relative to standard methods.

Effects of a multicomponent microbial feed additive containing prebiotics and probiotics on health, immune status, metabolism, and performance of newly weaned beef steers during a 35-d receiving period.

We examined the effects of dietary supplementation of a multicomponent blend of prebiotics and probiotics on health, immune status, metabolism, and performance of newly weaned beef steers during a 35-d receiving period. Eighty newly weaned crossbred steers (12-hour postweaning; 206 ± 12 kg of body weight [BW]) from a single source were stratified by BW into four pens (20 steers per pen) such that each pen had similar BW at the beginning of the experiment. The pens were randomly assigned to receive a corn silage-based diet with no additive (CON; two pens; n = 40 steers) or a basal diet supplemented with SYNB feed additive at an average of 28 g/steer/d (SYNB; two pens; n = 40 steers). The SYNB additive is a blend of live Saccharomyces cerevisiae and the fermentation products of S. cerevisiae, Enterococcus lactis, Bacillus licheniformis, and Bacillus subtilis and was supplemented for the first 21 d only. Percentage of steers treated for bovine respiratory disease (BRD) was calculated for each dietary treatment. Daily dry matter intake (DMI) and meal events (meal frequency and duration) were measured. Weekly BWs were measured to calculate average daily gain (ADG). Blood samples collected on days 0, 14, 21, 28, and 35 were used for ex-vivo tumor necrosis factor alpha (TNF-α) release assay following lipopolysaccharides (LPS) stimulation, plasma metabolome analysis, and mRNA expression analysis of 84 innate and adaptive immune-related genes. Compared with CON, supplemental SYNB increased (P ≤ 0.05) ADG, DMI, and meal events during the first 7 d. At d 21, there was no treatment effect (P > 0.05) on final BW, DMI, ADG, and meal events; however, beef steers fed supplemental SYNB had greater (P = 0.02) meal duration. Over the entire 35-d receiving period, beef steers fed supplemental SYNB had greater (P = 0.01) ADG and feed efficiency, tended to have greater (P = 0.08) meal duration, and had lower percentage (35 vs. 50%) of animals treated for BRD and lower percentage of sick animals treated for BRD more than once (7.15 vs. 45%). Whole blood expression of pro-inflammatory genes was downregulated while that of anti-inflammatory genes was upregulated in beef steers fed supplemental SYNB. Beef steers fed supplemental SYNB had lower (P = 0.03) plasma concentration of TNF-α after LPS stimulation. Six nutrient metabolic pathways associated with health benefits were enriched (false discovery rate ≤ 0.05) in beef steers fed supplemental SYNB. This study demonstrated that dietary supplementation of SYNB during the first 21 d of arrival reduced BRD morbidity, improved the performance, immune, and metabolic status of beef steers over a 35-d receiving period thereby extending the SYNB effect by a further 14 days post supplementation.

Delayed versus on arrival modified live viral vaccination in stocker cattle on bovine respiratory disease

PICO question&#x0D; In auction market calves at high risk of developing bovine respiratory disease (BRD), does delayed (14–30 days) vaccination with a modified live vaccine (MLV) for viral respiratory pathogens versus administration of MLV on arrival (within 24 hours of arrival) to the stocker operation, result in less calves with BRD morbidity diagnosed based on visual signs and rectal temperature &gt;40°C, or less calves with BRD mortality?&#x0D; &#x0D; Clinical bottom line&#x0D; Category of research question&#x0D; Treatment&#x0D; The number and type of study designs reviewed&#x0D; Four papers were critically reviewed. All were randomised complete block designs&#x0D; Strength of evidence&#x0D; Moderate&#x0D; Outcomes reported&#x0D; In stocker calves, delaying administration of a MLV for respiratory viruses may result in numerically lower initial BRD morbidity rates, while giving at arrival may result in numerically lower BRD retreatments. One study shows statistically lower cases of BRD morbidity after the third antimicrobial treatment in cattle vaccinated on arrival with both a clostridial and MLV for respiratory viruses compared to cattle vaccinated on arrival with clostridial vaccine and delayed MLV for respiratory viruses. No conclusion about mortality can be drawn due to inconsistent numerical conclusions between studies&#x0D; Conclusion&#x0D; Due to conflicting evidence and a general lack of statistically significant differences in morbidity and mortality outcomes, a definite answer regarding the impact of delayed MLV respiratory vaccination in stocker calves cannot be made&#x0D; &#x0D; How to apply this evidence in practice&#x0D; The application of evidence into practice should take into account multiple factors, not limited to: individual clinical expertise, patient’s circumstances and owners’ values, country, location or clinic where you work, the individual case in front of you, the availability of therapies and resources.&#x0D; Knowledge Summaries are a resource to help reinforce or inform decision making. They do not override the responsibility or judgement of the practitioner to do what is best for the animal in their care.&#x0D; &#x0D;

Scoping Review on Risk Factors and Methods for the Prevention of Bovine Respiratory Disease Applicable to Cow-Calf Operations.

Simple SummaryBovine respiratory disease (BRD) is common in cattle populations and has been named as one of three diseases where antibiotics are most frequently used in cow–calf operations in California. Antibiotics are typically used to treat or prevent the disease, but recent concerns about antibiotic resistance of pathogens in animals or spreading from animals to people have led to the call for more judicious use of these drugs. The present review summarizes the English scientific literature on articles about risk factors for the disease as well as ways to prevent BRD that are applicable to cow–calf operations. Numerous management and animal factors have been identified as increasing the risk for BRD. Vaccinations, metaphylactic use of antibiotics, and feed supplements are areas of research into the prevention of BRD. Genetics have also been explored to determine the heritability of BRD resistance. While vaccinations and metaphylactic use of antibiotics have been evaluated in multiple systematic reviews and meta-analyses, these types of summaries are missing for commonly studied feed supplements, such as yeast and trace minerals, and the use of nitric oxide releasing substance to prevent BRD. Further, it would be beneficial to summarize the knowledge on management related risk factors in literature reviews.The presented scoping review summarizes the available research evidence and identifies gaps in knowledge for bovine respiratory disease (BRD) prevention. Published literature on BRD from 1990 to April 2021 was searched in online databases, including Medline, CAB s, Scopus, Biosis, and Searchable Proceedings of Animal Conferences. Citations were systematically evaluated in a three-stage approach using commercial software and summarized in a scoping review format. A total of 265 publications were included in this review with herd/farm management (27.9%) as the most prevalent factors studied, followed by metaphylaxis (24.5%), vaccinations (24.1%), diet formulations, and nutritional supplementations (17.7%), animal characteristics (10.2%), and less common interventions and risk factors (6.4%). A high proportion of studies under herd/farm management (73%), metaphylaxis (86%), vaccinations (70%), animal characteristics (78%), and less common interventions and risk factors (59%) showed either significant effects on reducing BRD morbidity or significant differences of BRD between treatments. However, diet and nutritional supplementations reduced BRD only in 30% of research publications. Most studies on BRD were performed in feedlot populations, and more studies in cow–calf populations are needed. We further suggest meta-analyses on the use of yeast and trace mineral supplementation, and nitric oxide-releasing solution for BRD prevention.

86 Effect of Post-metaphylactic Interval on Health and Performance of Steers Administered Tildipirosin for the Control of Bovine Respiratory Disease

Abstract Crossbred beef steers (n = 8160; 294 + 10.4 kg) were used in a randomized complete block designed study to determine the effects of post-metaphylactic interval (PMI) on health, live and carcass performance. Steers were administered tildipirosin for the control of bovine respiratory disease (BRD) before being randomly allocated to PMI treatments (4-, 7-, 10-, or 13-day PMI). Treatments were replicated in forty - 204 head pens with each treatment represented within 10 arrival blocks. Blocks ranged from 4 to 15 unique sources of cattle representing five states (AR, FL, GA, LA, TX). Steers were observed daily (217 + 14 d) by trained pen riders with steers suffering from BRD receiving a common antibiotic therapy across PMI treatment. Data were evaluated using linear, quadratic and cubic contrasts. First pull BRD morbidity decreased linearly (P &amp;lt; 0.01) and tended to decrease quadratically (P = 0.08) as PMI increased with the greatest BRD morbidity at 7 days (12.9%) and the least at 13 days (9.5%). First pull BRD relapses tended to decrease linearly (P = 0.10) with increasing PMI. Total first pull morbidity, for all causes, decreased quadratically (P = 0.02) as PMI increased with the greatest morbidly occurring with a 7-day PMI (15.8%) and the least with a 13-day PMI (11.5%). Mortality caused by BRD (0.73%; P &amp;gt; 0.70) and all causes (1.41%; P &amp;gt; 0.20) or chronicity (1.60%; P &amp;gt; 0.15), resulting from failure to respond to therapy, were not affected by PMI. Final body weight, ADG, DMI, Gain:Feed, and HCW were not affected (P &amp;gt; 0.20) by PMI. Total and BRD morbidity can be reduced by increasing PMI up to 13 days in cattle at moderate risk of developing BRD (15% morbidity, 1% mortality, 1% chronicity) without adversely affecting mortality, chronicity or live and carcass performance.