KATHRYN GOODWIN-RAY MONDAY 12 MAY. 3.20pm. Johne s Management Ltd. Lamb pneumonia How big is the problem? Room 1

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1 KATHRYN GOODWIN-RAY Johne s Management Ltd Kathy Goodwin-Ray is currently working as an epidemiologist for Johne s Management Limited, a company monitoring Johne s disease in New Zealand deer. Her previous post-graduate research at Massey University involved the epidemiology of pneumonia in New Zealand sheep. She completed her PhD in Epidemiology at Massey University in 2006, and has published five peer-reviewed scientific papers. Lamb pneumonia How big is the problem? Pneumonia is a common disease of sheep in all major sheep-producing countries. In lambs it causes mortality, decreased growth and a predisposition to pleurisy, at considerable cost to the industry. A summary of the results of several studies conducted at Massey University between 1999 and 2003 will be presented, including: patterns of pneumonia prevalence and effects on lamb production from 15 farms; the comparison of on-farm factors of low and high pneumonia prevalence farms; the efficacy of a commercially available vaccine; average pneumonia prevalence estimates from three regions involving 1.9 million lambs from 1,719 farms; and an estimate of the cost of pneumonia and pleurisy in lambs to the sheep industry in New Zealand. Pneumonia is not routinely recorded at sheep processing plants but the data collected provides the most representative estimate of lamb pneumonia prevalence in the population of slaughter lambs to date. From December 2000 to September 2001 the pneumonia prevalence of 1.9 million lambs supplied to processing plants in Canterbury, Manawatu and Gisborne was 29%, 22% and 24% respectively. The prevalence of lamb pneumonia, its causes, effects, diagnosis, treatment and control strategies will be discussed. MONDAY 12 MAY 3.20pm Room 1 40 Follow us: #aginnovation

2 Lamb Pneumonia How big is the problem? Dr Kathy Goodwin-Ray

3 Lamb Pneumonia The Facts Common disease of all sheep producing countries Leads to Mortality Reduced Growth Pleurisy Complex disease involving Microbial agents Farming practices Environmental factors

4 Pneumonia Facts Only reliable diagnosis at slaughter Not routinely recorded at processing plants but pleurisy is After weaning, maternal antibodies decrease as lamb susceptibility increases Two recognised types Acute - clinical Chronic subclinical Massey studies focus on subclinical

5 Prevalence in New Zealand Subclinical pneumonia range 21 to 93% (various studies from Kirton et al 1976 to Goodwin-Ray et al 2004) Only prevalence estimate in broader population from January to September in ~2 million lambs (Goodwin-Ray et al 2008) 29% in Canterbury (10% moderate to severe) 22% in Manawatu (13% moderate to severe) 24% in Gisborne (7% moderate to severe)

6 Longitudinal Study 15 farms studied from Northland, King Country and Southland Sampling Procedure Random selection 400 lambs/farm Group A 200 lambs Weigh every 4 weeks Group B 200 lambs Weigh every 4 weeks Random slaughter of 40/month from weaning Slaughtered according to commercial selection criteria

7 Pneumonia prevalence (%) Patterns of Pneumonia Prevalence Randomly selected lambs Southland King Country Northland Dec Jan Feb Mar Apr May

8 Pneumonia category Effect of pneumonia on growth rate in month preceding slaughter of randomly selected lambs Average daily grow th rate (g/day)

9 Number of lambs Chicory vs. Pasture Northland 656 lambs split into two groups - chicory or pasture grazed, 2 farms, random slaughter selection Prevalence not significantly different but more severe pneumonia in pasture-fed Pasture Chicory lambs Pneumonia category

10 Proposed factors predisposing lambs to pneumonia Stress, conditions promoting cross colonisation of pathogens- grouping together of animals (Alley, 1987) Heat, crowding, exposure to inclement weather, poor ventilation, high moisture levels, handling, transport (Knowles et al, 1995) Castration, docking, weaning, changes in diet, exhaustion and hunger during transportation (Cole, 1996) High loads of parasite, mixing of animals from different sources (Martin, 1996) Extensive stressful exercise under experimental conditions (Anderson et al, 1991), and cold temperatures (Diesel et al, 1991) Dust (Davies 1985, Bruere et al 2002)

11 Case Control Study Data collection by AsureQuality meat inspectors in Canterbury, Feilding and Gisborne over 8-10 months Pneumonia classification Minor <10%: Major >10%: lung surface area lung surface area

12 Number of farms Farm selection Total 2,195 farms and 1,083,387 lambs monitored over 3-4 months, farms with <100 lambs total excluded Control farms 253 Case farms Major pneumonia prevalence 191 case farms, 302 control farms sent retrospective questionnaire of farm characteristics and management

13 Risk & Protective factors for pneumonia Shearing lambs at weaning Breeding own ewe replacements Purchase of lambs post weaning Increasing risk of pneumonia large number of lambs sold to meat plants Increased average slaughter age of lambs Set stocking lambs post weaning Vitamin B12 treatment at tailing and weaning?

14 Vaccination Trial Ovipast Plus contains most common bacterial pathogens of pneumonia 7 commercial sheep farms in lower North Island all with a history of pneumonia Within 6 weeks after weaning, half of all lambs within each flock were vaccinated twice (n=8,364) with an interval of 4-6 weeks (vaccinates), the other half were injected simultaneously with a placebo (control group) Lambs weighed at first vaccination, two other times throughout trial and prior to shipment to processing plant

15 Results Pneumonia significant effect on lamb growth rate ADG in month preceding slaughter 136 g/day lambs without pneumonia, 64 g/day lambs with extensive pneumonia No significant effect of vaccination on ADG or pneumonia prevalence at slaughter Pneumonia prevalence 54% Vaccine no longer on the market Other opportunistic microorganisms may fill role of pathogen once immunity to one strain of M. haemolytica is established Vaccine control?

16 Major Pneumonia Prevalence (%) Pneumonia Prevalence estimates per farm over 8-10 months from 1.9 million lambs in Canterbury, Feilding and Gisborne Dec Jan Feb Mar Apr May Jun Jul Aug Sep Canterbury Feilding Gisborne

17 Prevalence Prevalence (%) Prevalence (%) Pleurisy Prevalence compared to Pneumonia Prevalence Major Pnueumonia Canterbury Pleurisy Major Pnueumonia Feilding Pleurisy Dec Jan Feb Mar Apr May Jun Jul Aug Sep Gisborne Major Pnueumonia 0 Dec Jan Feb Mar Apr May Jun Jul Aug Sep Pleurisy Dec Jan Feb Mar Apr May Jun Jul Aug Sep

18 Estimated Cost to Industry Based on: The effect of pneumonia on growth rate prior to slaughter (14 flocks) The prevalence of pneumonia (>10%) and carcasses downgraded due to pleurisy (1,719 flocks) Data of annual slaughter statistics and carcass value in NZ Cost of Pneumonia $37.4 million/annum, Pleurisy $33.3 million/annum Total cost $70.7 million per annum

19 Conclusions Widespread disease in NZ Randomly slaughtered lambs 7% to 82% in Dec to Mar Commercially selected slaughter lambs Major Pneumonia prevalence 1.4% to 33% in Jan to May Average pneumonia prevalence of 2,241 commercial flocks 26% Reduction in growth rate month prior to slaughter 50% if pneumonia >20% lung area Many proposed risk factors, our study (shearing at weaning, breeding own replacements, purchase of lambs post-weaning, increased average slaughter age)

20 Conclusions Vaccines often successful under experimental conditions but not pastoral farming conditions Wide range of micro-organisms capable of causing pneumonia In absence of effective vaccines farm management practices important to reduce the effects of pneumonia Significant economic cost from reduced growth rate due to pneumonia and carcasses downgraded due to pleurisy $70.7 million/annum

21 Control strategies Ensure adequate nutrition and animal health management to provide a robust immune system Minimise stressors Avoid shearing lambs at weaning Market lambs early to avoid peak months of pneumonia March-May Minimise time lambs grouped together Avoid mixing lambs from different sources