DISEASE ERADICATION
In this session you will learn: The diseases that are amendable to eradication. Methods of disease eradication: Which method is best suited to which disease. Relative advantages & disadvantages of each.
Quizz: How does disease impact on herd performance? From A woman s guide to car buying
Disease impacts significantly on herd performance by: reducing feed intake reducing growth rate reducing feed efficiency by directing protein toward tissue repair or the immune response increasing mortality rate reducing reproductive performance increasing pre-weaning mortality rates increased medication costs (typically around 10c/kg dressed) impact on staff morale
Where do pathogens come from? 99% of pig diseases enter a herd through the entry of an infected animal 1% aerosol spread (eg. Mycoplasma can travel 2-3km) fomites (dirty boots and overalls) vectors (eg mosquitoes can carry PRRS).
QUIZZ: How then do we keep pathogens out? (Select the 3 best ones!) >3km from other piggeries Shower in and out Use footbaths extensively Have a fence surrounding the farm Clean boots & overalls for visitors Bird-proof sheds
Which pathogens should we target? Mycoplasma hyopneumoniae Actinobacillus pleuropneumoniae Brachyspira hyodysenteriae Sarcoptes scabei Lawsonia intracellularis? Brachyspira pilosicoli?
Which pathogens can t we eradicate (yet)? Erysipelothrix Haemophilus parasuis E coli Streptococcus suis.
Options for disease eradication Depopulation-repopulation Swiss depopulation Segregated early weaning Snatch farrowing Prolonged medication
Which eradication program? What diseases do you wish to eradicate? Do you want to keep your genetics? What time of year is it? What are pig prices like? How big is your herd? Do you have access to off-site facilities?
Depopulation-repopulation Out with the old-in with the new! Minimise the period when no pigs are being sold Eg.. Buy pregnant gilts Maximise the income from dispersal of dirty pigs Eg.. Do it in the last 6 months of the year Optimise income from the first clean pigs
Depopulation-repopulation Sell off stock One-off dispersal sale Targetted dispersal Farrow sows & transfer growers off-site & sell from here (ideal-lowest lowest down time) Stop mating, sell off sows at weaning & sell progeny at normal weights (most common)
Depopulation-repopulation repopulation-an an example Staff Education Stop mating in April-stop selling last week in January Clean & repair Rodent control Staff holidays?? Re-stock with clean pigs
Depopulation-repopulation Be prepared for. Greasy pig Colibacillosis Strep suis Glassers disease Proliferative enteritis
Swiss depopulation From What women want in a car
Swiss Depopulation-what is it? Targetted at Mycoplasma hyopneumoniae Can be combined with mange & SD Based on observations that adults (>10 months of age) do not shed MH Medication + vaccination further reduces the risk
Swiss Depopulation-what are the rules? Close the herd so only adult stock >10mo on site (includes suckers) No farrowings for 14 days during medication period of remaining stock Fully vaccinate all adults B4 Clean & disinfect facilities
Example : Medication program Close the herd so that there are no pigs < 10 months Vaccinate whole herd with MH (2 shots B4 start of Swiss depop) 14-day non-farrowing period Medicate whole herd with Lincomycin @ 8mg/kg for the 14 days Clean and disinfect
Segregated early weaning Popularity fading Is it the segregated or the early? Basics-minimise shedding from sow (medication/vaccination-mew) + wean piglets while they are still protected by maternal antibody Various combinations/permutations
Snatch farrowing Manual removal of piglets at farrowing Clean piglets transferred to clean site Undertaken on a large farm in North Central Victoria in mid 80 s Colostrum-deprivation risk-may result in high piglet losses from Colibacillosis
Prolonged medication Targeted at swine dysentery Assumes: Faeces of carrier pigs are the only source of infection (ie( ie.. rodents are eliminated & the environment cleaned) 3-66 weeks high medication will eliminate SD from the carrier pigs Low medication for a further 8-188 weeks will prevent re-infection as the organism dies out
Prolonged medication Various medication strategies Lincomycin Tiamulin Dimetridazole (DMZ)
Prolonged medication Six Must dos Establish a diagnosis of SD and sensitivity Ensure feed is medicated accurately Implement a system to ensure correct feed delivery Implement good rodent control/eradication Ensure a good clean so all faeces is removed from pens Follow withhold periods for antibiotics
On-farm eradication of Mycoplasma hyopneumoniae,, Actinobacillus pleuropneumoniae and swine dysentery Trish Holyoake BVSc PhD University of Sydney trishh@camden.usyd.edu.au
We need clean pigs but we don t want to compromise our genetics What are our options?
What pathogens were we dealing with? Mycoplasma hyopneumoniae Actinobacillus pleuropneumoniae (strain 7) Brachyspira hyodysenteriae
What were our options for eradication? 1. Depopulation-repopulation - Wanted to keep genotype 2. Snatch-farrowing - High labour requirement - Piglet mortality problems with E coli 3. Swiss depopulation - Will it eradicate APP? 4. Medicated early weaning - Again, what about APP?
What were the principles of the MEW/Swiss depop? Maximise maternal immunity to piglets P2+ sows Vaccinated with MH and APP pre-farrow Minimise pathogen transfer from sow to piglets Ceftiofur (Pulmotil )) to sows @ 15-25mg/kg pre & post farrowing Tiamulin to sows @ 6-16mg/kg 6 pre & post-farrowing Maximum weaning age 10 days Second line of defence Ceftiofur (Excenel )) IM to piglets pre-weaning Tilmicosin (Pulmotil )) in-feed post-weaning
What we did Selected 32 old sows (P2+) from the breeder site These gals were 4 weeks off farrowing Trucked them 300km to an empty farrow/breeder site Placed them directly into farrowing crates Vaccinated them using MH (Suvaxyn( M hyo ) & autogenous APP (Intervet( Intervet) ) vaccines on arrival & 2 weeks later Fed them with a diet containing 1250ppm Pulmotil (15mg/kg+) & 800ppm Tiamulin (6mg/kg+) They had to eat 3kg/day
Cross-parity serology of the sow 7.5 herd for MH Positive 5.0 2.5 Positive/Suspect 0.0 1 2 3 4 Parity MH titres high in some gilt progeny recent infection
Farrowing to weaning Administered PG (Lutalyse( Lutalyse ) to all sows at 113d+ gestation on 1 day Weaned sows off-site when the oldest litter was 10 days of age Administered 1mL Excenel IM to piglets at weaning Piglets reared in farrowing crates until they were 6 weeks of age Fed a non-medicated milk-replacer + creep/weaner diets containing 400ppm Pulmotil
MEW pen with sow & crate removed
MEW runt pen
At the grower site 276 pigs moved to an off-site grower site Non-medicated feed Amoxycillin in-water @ 10mg/kg for 3 days in 21 to prevent proliferative enteritis Processed at 22-23 23 weeks of age
Little pigs & big pigs! MEW grower site
Little pigs & big pigs! MEW grower site
Confirming pathogen freedom Mycoplasma hyopneumoniae Serology low sensitivity in low pressure environment PCR as backup on suspect lungs Actinobacillus pleuropneumoniae 7 Serology sensitivity/specificity? PCR as backup on tonsillar swabs Brachyspira hyodysenteriae No sensitive ante-mortem test in clinically healthy pigs
Vital stats 31 of the 32 sows farrowed 315 piglets born alive (10.2% avg) 29 litters weaned at 9 days of age + 2 litters weaned at 7 days of age 12.4% pre-weaning mortality 7% post-weaning mortality
Carcass weight (HSCW), backfat P2 and ADG (birth to bacon) of pigs Batch Males Females HSCW (kg) Back fat (mm) ADG* (g/d( g/d) HSCW (kg) Backfat (mm) ADG (g/d( g/d) 1 77.77 12.88 673 78.15 13.84 677 2 68.24 14.1 565 73.49 14.69 609
Diagnostics
Necropsy data 6 of the 19 pigs that died were necropsied 4 twists 1 haemorrhagic stomach ulcer 1 meningitis ( (S suis isolated) No pathology consistent with APP or BH at processing 40 suspect MH lungs at processing were submitted for PCR 1 pig had small intestinal pathology consistent with proliferative enteritis at processing
Mycoplasma hyopneumoniae 2/64 bloods collected at processing were positive on Dako ELISA Both were in Well #1 on the ELISA plates lab interpreted negative result 40 suspect lung samples collected at processing were negative by MH PCR
Actinobacillus pleuropneumoniae 7 PCR on tonsillar swabs submitted to DPI & EMAI -tonsillar swabs taken from 21 pigs (8 weeks of age) on a known +tive farm were pooled 3:1 >> 1 pooled sample was positive -tonsillar swabs also taken from 21 pigs (8 weeks of age) on a suspect tive farm were also pooled 3:1 >> 3 pooled samples were positive!! -tonsillar swabs from 21 pigs (11 weeks of age) from the MEW trial pooled 3:1 >> no pooled samples were positive
Serology for APP 7 Sera sent to EMAI for 2 non strain-specific specific ELISAs (ApxIV & 39Kd) 64 bloods from MEW pigs at processing all negative by both tests 10 negative control sera (pre-suckle) all negative by both tests 3 strain 15 +tive+ controls (from a strain 15 pos herd) 1 pos, 2 suspect +tives+ (39Kd test) 1 pos, 2 neg (ApxIV( test) 10 strain 7 +tive+ controls (from a strain 7 pos herd) All neg (39Kd test) 3/10 suspect +tive+ (ApxIV test)
Costs Sows Feed (gestation, lactation, creep, grower) Agistment (rental on breeder & grower farms) Labour Medication (vaccination, medication) TOTAL = $113/pig
Summary We undertook a combined MEW/Swiss depop program to attempt MH, APP and BH eradication To the best of our current diagnostic capabilities, we were successful in our eradication attempt
In this session you should have learnt: The diseases that are amendable to eradication. Methods of disease eradiction: Which method is best suited to which disease. Relative advantages & disadvantages of each.