OSU/OVMA Summer Seminar

Transcription

1 OSU/OVMA Summer Seminar Stillwater, Oklahoma June 12, 2015 DL Step, DVM, DACVIM Blake Wilson, PhD Clint Krehbiel, PhD Oklahoma State University Stillwater, Oklahoma

2 Ancillary Therapy for Bovine Respiratory Disease

3 Treating Cattle: Discussion goals: Introduction Bovine Respiratory Disease Brief review of industry challenges & immune response Ancillary Therapy for BRD Experiment 1 = Effects of ANC administration in high-risk calves treated for clinical BRD Experiment 2 = Effect of BRD incidence on finishing performance and carcass characteristics Have fun & ask questions

4 Challenge Feeder calf supply available in southeast US Small herds Acquired & commingled with cattle of like size, weight, type, gender Distance & time to reach preconditioningbackgrounding facility in High Plains high risk of exposure & development of BRD

5 Challenge Stressed cattle may not respond with an optimal immune response

6 Pathogenesis Virus + bacteria + stress dz Immunosuppression Or immune response Allows colonization of lower airways by potential bacterial pathogens

7 Review Immune Response Respiratory tract lined with epithelium Continuously exposed to potential pathogens Dynamic response Innate immunity = non-specific, usually rapid Adaptive immunity = specific, generally 1 pathogen

8 Cellular Defense Several cell types Respiratory epithelial cells Lymphocytes Dendritic cells Alveolar macrophages (AM) Polymorphonuclear leukocytes (PMN)

9 Cellular Defense (cont d) Alveolar macrophages & PMNs phagocytose pathogens Alveolar macrophages, PMNs, & epithelium secrete cytokines (chemical messengers) & host-defense peptides Neutralize pathogens Recruit other immune cells Initiate inflammation Coordinate immune function

10 Alveolar Macrophage AMs Comprise approx 80-85% cells in BAL fluid Initiates inflammatory response Production of proinflammatory cytokines induce vascular changes allow PMNs to migrate into the airways

11 B Lymphocytes Plasma cells = secrete large quantities of Igs Igs on respiratory epithelium surface from B cells in the tissues underlying the resp epithelium Ig-producing B cells most numerous in lg airways with # in smaller airways Cattle = > 4 months IgA containing cells ( 65%) most common underlying resp epithelium, followed by = IgG1 ( 20%), IgG2 ( 10%), IgM ( 10%) Memory cells = persist, rapid expansion following potential future exposure to Ag Ig response

12 Predominant Immunoglobulin Isotype Nasal mucosa = IgA BAL fluid = similar [ ] IgG & IgA Serum = IgG Supports role of IgA in local mucosal immunity

13 Approaches NAHMS 2013 Tx protocols vary between feedlots Standard practice = antimicrobial tx BRD 99% used an injectable antimicrobial as primary tx for BRD

14 Ancillary Therapy Treatment in combination with prescribed antimicrobial Primary goal = improve cattle s response Ancillary therapy generally focuses on clinical signs &/or improving immune response

15 Surveys NAHMS 2001, Terrell 2011, NAHSM 2013 Veterinarians & feedlot operators Majority of feedlots administer some form of ANC Frequency varies over time Most common ANC include = Antihistamines B vits Corticosteroids DFMs NSAIDs Viral vax Vitamin C

16 Experiment 1 Evaluation of multiple ancillary therapies utilized in combination with an antimicrobial in newly received high-risk calves treated for bovine respiratory disease Objective = evaluate 3 commonly ANCs in combination with an antimicrobial

17 Materials & Methods Cattle 516 mixed breed steers & bulls Arrival BW = 477lb +/- 44lb (217kg +/- 20kg) Obtained over 1 week period from multiple auction markets in Oklahoma Shipped to WSBRC avg distance = 81 miles (135 km)

18 Materials & Methods (cont d) Cattle commingled into receiving pens Access to prairie hay & water (automatic waterers) Rest prior to processing hrs Standard receiving processing protocol

19 Materials & Methods (cont d) Cattle observed 2X daily DART (Pharmacia Upjohn Animal Health) with modifications Subjective evaluations = Depression, Appetite, Respiratory signs Clinical severity score 1 = mild clinical signs 2 = moderate clinical signs 3 = severe clinical signs 4 = moribund

20 Materials & Methods (cont d) DART (Pharmacia Upjohn Animal Health) with modifications Objective evaluation = Temperature 104⁰F (40⁰C)

21 Materials & Methods (cont d) Steers with clinical score (CS) 1-4 were pulled from home pen, moved to processing facility for rectal temperature & further evaluation Unless reasoned animal would be worse with movement, allowed to stay in home pen & treated (CS = 4)

22 Materials & Methods (cont d) Treatment with antimicrobial and CS = 1 or 2 + rectal temperature 104⁰F Tx CS = 1 or 2 + rectal temperature < 104⁰F NO Tx CS 3 or 4 Tx regardless of rectal temperature All cattle returned to receiving home pen after evaluation following Tx protocol outlined above (case definition)

23 Materials & Methods Antimicrobial Tx protocol for clinical BRD Maximum 4 Txs

24 Experimental Treatments Randomly assigned to 1 of 4 Txs NOAC = antimicrobial only, no ancillary Tx NSAID = antimicrobial + flunixin meglumine 1mg/lb IV (2mL/100lbs BW) VACC = IBR viral vax 2mL dose IN VITC = vitamin C injection 10mL/calf IM 4 pens/ Tx; 80 hd/tx At time of pull = CS, BW, Temp BW all cattle days 28 & 56

25 Analysis MIXED procedure SAS Pen = experimental unit Contrasts were performed Ave 3 ANC (NSAID, VACC, VITC) vs control (NOAC) Deads & removals backed out at calculated maintenance intakes

26 Results Experiment 1

27 Results

28 Results (cont d)

29 Results (cont d)

30 Mortality, Removals No differences (P = 0.55) in % mortality among ANC groups NOAC did exhibit numerically mortality compared to other ANC groups No differences (P = 0.13) in removals among ANC groups However, when ave of 3 ANC contrasted against NOAC, NOAC calves removed from experiment at a greater rate (P = 0.05) mortality + removals resulted in no difference (P = 0.98) of calves able to complete experiment

31 Results (cont d)

32 Summary & Conclusions Exp 1 Cattle experienced natural challenge Morbidity = 66.5% CFR = 13.2%

33 Summary & Conclusions Exp 1 2 positive responses to ANC observed Calves receiving VACC tended to be treated a second time for BRD less frequently Calves receiving NSAID or VITC tended to be treated a third time for BRD less frequently These tendencies for improvements in BRD treatment percentages Likely the result of numerical differences in time intervals Days between BRD treatments Days from arrival or BRD treatment to death

34 Summary & Conclusions Exp 1 NOAC vs ave of 3 ancillary Txs Significant improvement or tendencies for improvement BW, ADG, DMI over multiple intervals ANC treated for BRD No benefit measured to calf health or performance ANC may not be beneficial to calf performance during the receiving period to severely challenged cattle

35 Experiment 2: Finishing ANC Impact of receiving ancillary therapy utilization on steer finishing performance, efficiency, carcass characteristics, and lung scores

36 Objective Exp 2 Evaluate the effect of BRD incidence during the receiving period on subsequent finishing performance, efficiency, carcass characteristics, & lung scores in feedlot steers

37 Materials & Methods (cont d) Calves sorted by # Txs for BRD (BRDX) Never Tx (0X) Tx once (1X) Tx twice (2X) Tx 3 or 4 times (3/4X) Steers allocated to 32 finishing pens; 8 pens per BRDX group)

38 Materials & Methods (cont d) BW finishing period obtained approx 45 day intervals Ultrasound collected on 2 weigh days Last 28 days finishing period fed ractopamine HCl mg/hd/d Steers harvested in 2 groups Carcass data collected at harvest Lung consolidation scores Lung adhesion scores

39 Materials & Methods (cont d) Data analysis using MIXED procedure of SAS Contrasts performed Linear & quadratic contrasts for BRDX Marbling number & % US Prime & Choice carcasses Harvest group included in model statement Mortalities included in analysis (n = 4) Digestives = 3 BRD = 1

40 Results Experiment 2

41 Results BW at arrival for preconditioning did not differ among BRDX (P = 0.17) BRDX during receiving period impacted ADG

42 Results (cont d)

43 Results (cont d)

44 Results (cont d)

45 Results (cont d)

46 Results (cont d)

47 Results (cont d)

48 Results ANC Therapy (cont d)

49 Results ANC Therapy (cont d)

50 BRD Economics Base grid carcass price $199.87/100lb Ration cost DM basis = $301.82/Ton Yardage $0.40/hd/day Actual grid premiums & discounts Actual antimicrobial cost & ave dose Actual DMI & head days Assumed $7.25 labor to Tx BRD

51 Results (cont d)

52 Summary & Conclusions Exp 2 Steers were able to finish to a common physiological endpoint BRDX animal performance during finishing

53 Summary & Conclusions Exp 2 BRDX linear in consolidation of lung tissue linear in HCW, dressing %, & REA tendency to % US Prime & Choice carcasses With BRDX Carcass value

54 Summary & Conclusions Exp 2 Actual antimicrobial cost was <$15.00 for each BRD Tx 2011 NAHMS study = $23.60 Labor? Cattle prices change

55 Summary & Conclusions Exp 2 With additional DOF steers treated multiple times for clinical BRD Can obtain similar physiological end points compared to untreated cohorts Likely never reach the same quality & yield potential loss in carcass value

56 Summary & Conclusions Exp 2 Must also consider Additional Tx costs, labor, yardage, & feed consumption End result = reduction in total value of steers 1X = 2.4% 2X = 8.9% 3/4X = 12.3%

57 Questions