5. Bovine Respiratory Disease (BRD)

Feedlot Nutrition and Production: Bovine Respiratory Disease (BRD)

• Bovine Respiratory Disease (BRD) is also known as shipping fever

BRD Aetiology and Pathogenesis

• Infectious challenge plays a minor role in BRD (Martin et al, 1998)
• Research suggests the infectious challenge can be modified by the presence of Bovine Viral Diarrhea Virus Persistent Infections, though results vary (Loneragan et al, 2003; O'Connor et al, 2005)
• An increase in serological responses slightly elevates BRD risk
• Mycoplasma bovis infection potentially increases BRD risk

Clinical Signs and Diagnosis

• Clinical signs are used to determine which animals to pull for treatment

Post-mortem Findings for BRD

• Post Mortem pathological investigations contribute to diagnose BRD in affected livestock

Treatment for BRD

• Common pharmaceuticals for treatment are:
• Tulathromycin
• Tilmicosin
• OTC
• Ceftiofur
• Florfenicol
• Additional treatments include Vitamin C and NSAIDs

Vitamin C as a BRD Treatment

• Acts as an anti-oxidant, and can act as a pro-oxidant at a high concentration
• Cattle are generally though to have endogenous production to meet their requirement
• Morbidity lessens when trade cattle are treated with 5g of vitamin C during BRD treatment (approx. ½, P = 0.04, n = 100)
• A successful dosage rate is 14 mg/kg BW

Infectious Bovine Rhinotracheitis (IBR)

• Aetiology and Pathogenesis is similar to BRD
• Diagnosis depends on animals pulled for treatment for IBR
• Treatments are:
• Antibiotics, as outlined for BRD
• NSAIDs
• Vitamin C

Prevention of Bovine Respiratory Disease

• Prevention strategies include addressing predisposing factors, animal preparation and feedlot management

Predisposing Factors That Increase BRD Incidence

• Risk factors include:
• Season and weather patterns (Australian & North American)
• Dust concentration (US studies)
• Gender, trending towards greater risk in steers (Australian & North American)
• Breed and virus contraction

Climate Data Correlations with BRD Incidence

• Pearson's correlations between climate data and daily incidence of bovine respiratory disease treatments and mortalities were measured from 10/6/2004 to 19/8/2004
• Daily incidence of BRD is correlated with:
• Mean daily Ta (° C) at -25.3 with P value of 0.05
• Minimum daily Ta (° C) at -39.8 with P value of 0.002
• Daily Ta range (° C) at 25.2 with P value of 0.05 Daily rainfall (mm) at -14.5 with P value of 0.26 Mean wind speed (km/h) at -13.4 with P value of 0.30 Maximum wind speed (km/h) at -22.6 with P value of 0.08

National BRD Initiative 2014

• The National BRD Initiative identified the odds ratio and Bayesian P Value for each season
• Seasons as base:
• Summer: 2.4 (1.4 to 3.8) with P Value of 0.001
• Autumn: 2.1 (1.2 to 3.2) with P Value of 0.004
• Winter: 1.6 (1.0 to 2.3) with P Value of 0.03

Breed Contribution to BRD Odds Ratio

• The National BRD Initiative identified the odds ratio and Bayesian P Value for each breed
• Breeds include:
• Hereford 2.0 (1.5 to 2.6) with P Value of less than 0.001
• Shorthorn 1.2 (0.9 to 1.6) with P Value of 0.080
• Brit x 1.2 (1 to 1.4) with P Value of 0.007
• M Grey 0.5 (0.3 to 0.8) with P value of 0.001
• Euro x 0.8 (0.5 to 1.2) with P value of 0.169
• Bos indicus X 0.5 (0.3 to 0.7) with P value of less than 0.001

Serological Contribution to BRD Odds Ratio

• The National BRD Initiative identified the odds ratio and Bayesian P Value for each virus. N = 6477.
• Virus factors include:
• BHV1: 1.4 (1.2 to 1.6) with P value of less than 0.001
• PI3: 1.4 (1.2 to 1.7) with P value of less than 0.001
• BRSV: 1.4 (1.3 to 1.7) with P value of less than 0.001
• BVDV: 1.3 (1.1 to 1.6) with P value of 0.001

Serological Increase To Respiratory Viruses Statistics from the National BRD Initiative

• No. of viruses correlated against the odds ratio and Bayesian P Value
• 1 virus 1.3 (1.1 to 1.6) with P Value of 0.003
• 2 viruses 1.9 (1.5 to 2.3) with P Value of less than 0.001
• 3 viruses 2.1 (1.6 to 2.6) with P Value of less than 0.001
• 4 viruses 1.8 (1.1 to 2.7) with P Value of 0.006

Disease Prevention Through Animal Preparation

• Animal preparation practices with robust supporting evidence include yard weaning and reducing transport time/distance

Yard Weaning

• DAN069 ± vaccination significantly reduced the liklihood of BRD
• US studies have shown similar benefits to weaning with vaccination (P < 0.001) when weaning without vaccination 45 d before feedlot delivery.
• A modified live viral vaccine and a Mannheimia haemolytica toxoid was used

Reducing Transport Time/Distance

• NBRDI (2014) shows transport time is a factor. BRD is more likely if transport is ≥ 6h within 24h of feedlot entry (OR = 1.2 (95% CI = 1.0 to 1.5, P = 0.02)
• IRR increases with each 160km of transport with a IRR of 1.001 with increasing distance (P < 0.001) (Sanderson et al. (2008))
• Distance travelled is also associated with BRD morbidity and overall mortality (Cernicchiaro et al. (2012) with (P < 0.05)

Animal Preparation Practices With Equivocal Supporting Evidence

• Pre-vaccination with Bovilis MH (2 injections) show registration data with epidemiological support
• Epidemiological data supports the practice of pre-vaccination with Pestigard (2 injections)

National BRD Initiative 2014 Vaccination against M. haemolytica and BVDV (2 shots)

• BRD Odds Ratio with selected treatment:
• Bovilis MH - 0.8 (0.6 to 1.0) with Bayesian P Value of 0.02
• Pestigard - 0.8 (0.5 to 1.1) with Bayesian P Value of 0.05

Bovine Respiratory Disease and Bovilis MH Injections

• Single injections of Bovilis MH or Bovishield at feedlot entry (n = 1660) with cattle placed directly in the feedlot
• Increase in ADG with Bovilis MH injection (0.06 kg/hd/d; P = 0.01), Bovishield result intermediate but not significant

Meta-analysis review of bacterial and viral vaccines

• A systematic review and network meta-analysis by O’Connor et al was conducted regarding bacterial and viral vaccines, administered at or near arrival at the feedlot, for control of bovine respiratory disease in beef cattle

Meta Analytic Study Parameters

• 53 initially eligible studies from 5 countries were used, mainly the US and Canada
• The study was cut down to 14 based on single products linked in the largest network to true negative controls
• 17 vaccines and 73 treatment arms were used

Meta-Analysis Conclusion

A study found no evidence that vaccination of beef cattle upon feedlot arrival is effective in reducing BRD incidence

Animal preparation practices with minimal supporting evidence or untested

• Pre-vaccination with Bovishield
• Truck design/exhaust fumes
• Hydration status on arrival at feedlot
• Higher pre-feedlot growth rate

Prevention of Bovine Respiratory Disease through Feedlot Management Practices

• Feedlot management practices with robust supporting evidence include:
• Reducing purchase groups per pen, while avoiding saleyard purchases
• Implementing local backgrounding
• Limiting shared water troughs between pens
• Reducing time to fill a pen with a complete batch of cattle
• Mass medication with antibiotics
• Adhering to an introductory diet
• Management of feed Delivery
• Using dietary vitamin E
• Limiting concurrent Disease
• HGP

Reduction in purchase groups & direct purchase

• Pen group weaning to feedlot entry increased ADG first 37d (DAN.069)
• Greater morbidity & mortality with mixing (Canadian Bruce County)
• Increased BRD with commingling, OR = 3 (95% CI 2.5 to 3.6) (US – O’Connor et al.(2005))
• An IRR = 2 (P < 0.001) with multiple sources in US – Sanderson et al. (2008)
• Increased BRD with saleyards v paddocks (12% v 6%, P < 0.001) (Aus – Croft et al. (2014))

Critical Timing: NBRDI, 2014

• Less mixing and saleyrd exposure can reduce BRD
• Mixing > 27d before feedlot entry transaction Associated with decreased BRD dependent on subsequent mixing, 0.6 to 0.8
• Total effect of saleyard exposure 27 to 13d Before feedlot entry is associated with greater BRD (OR = 1.9, 1.3 to 2.7, P = 0.001)
• Total effect of saleyard exposure ≤ 12d Before feedlot entry is associated with markedly increased BRD OR = 2.6, 95% CI = 1.6 to 4.1, P < 0.001

Attenuation

• Attenuation of Direct effect of saleyard exposure ≤ 12d before feedlot entry, but are still important OR = 1.6, 95% CI 0.9 to 2.6, P = 0.05

Cusack, Bergman, Hay and Morton (2021) on Vaccination Against Bovine Viral Diarrhoea Virus

• 7302 cattle across 6 sites in Australia that were allocated to 8 respiratory vaccine groups, including negative controls, between November 2009 and February 2017 on entry to backgrounding facilities contiguous with each feedlot.
• Conclusions: Accounting for respiratory vaccine effects, financial analysis suggests existing respiratory vaccines are not warrented

Feedlot Management With Minimal to no Benefit

• With minimal evidence to support dietary needs
• Supplementation with: Zinc and Cooper
• Liquid Supplementations - Urea and molasses

Dietary Trace Element Suprasupplementation Notes

• Supra supplementation is defined as an organic or inorganic approach, and is measured for morbidity effect
• Refer to Tables on slides 97-100 to review specific supplements

Dietary needs for Cattle (NRC)

• Diets should account for the basal concentrations of dietary zinc and ensure lower stress handling when preparing meal protocols

Feedlot practices shown not to reduce BRD incidence

• Vitamins A, D & E at feedlot entry
• In-feed Antibiotics
• Urea-molasses liquid supplement in starter pens
• Dietary sweeteners

Atypical Interstitial Pneumonia

• Is is primarily and allergic response to – H2S, NH3, CH4, molds
• Is of low incidence in local Australian feedlots
• Is a Diffuse interstitial emphysema