Before Vaccinating against Respiratory Diseases, Calculate

by 5m Editor
26 May 2009, at 12:00am

Decisions to vaccinate growing pigs against respiratory disease is usually based on past experiences of clinical problems – or perhaps as a result of adverse British Pig Health Scheme (BPHS) reports – and therefore, the need to protect the next batch of pigs, according to John Richardson from Intervet/Schering Plough Animal Health.

The response to vaccination is usually measured over time in terms of reduced mortality, fewer clinical problems, improved BPHS scores and possibly some considerable time later the measurement via herd records of improved growth rate and feed conversion ratio (FCR).

At least two factors confound this simplistic approach. Firstly, which pathogens are causing the Pig Respiratory Disease Complex (PRDC)? It is most probable that more than one is the cause of the problem, hence which vaccines should be used. Second, can we accurately predict both the improvement in pig performance and profitability as a result of vaccination? It would be ideal if we could calculate this before spending time and money on vaccines.

ResPig® has been developed by Intervet to assist pig veterinarians and their pig farming clients to do exactly this, and much more.

There are three integral components to ResPig, and each is of great value:

  1. A detailed audit of production
  2. Diagnosis of the key respiratory pathogens, and
  3. Economic impact simulation showing the cost of disease and benefits from of an appropriate vaccination regime.

Step 1. Production audit

The audit is done by an experienced person who objectively assesses aspects such as biosecurity, housing, pig-flow, nutrition and management of pigs from post-weaning to sale in each stage of production. A simple scoring system is used for each factor assessed from 0 (very good) to 3 (indicating poor and in need of attention).

Step 2. Diagnosis of respiratory disease

This is a key area and yet so often pig producers are unwilling to invest to enable their vet to conduct a full range of tests to identify when and which pathogens are present.

In support of customers, Intervet will sponsor detailed testing of blood samples for major respiratory pathogens, also the independent post-mortem of three pigs via the Veterinary Laboratories Agency. This information when combined together with recent BPHS reports and a clinical assessment by the farmer's vet enables a precise diagnosis of incidence and degree of severity of disease present on the unit to be made. Each disease is then scored as either 0 (indicating not present), 1 (moderate), 2 (considerable) or 3 (severe).

Step 3. Economic impact simulator

Using the herd's own performance data, costs of production and financial returns, together with the diagnosed severity of disease, the simulator can then show in detail the response to a range of vaccination permutations. These range from no vaccination, single vaccination against either Mycoplasma hyopneumoniae (M-hyo), porcine reproductive and respiratory syndrome (PRRS), porcine circovirus (PCV) or Actinobacillus pleuropneumonia (APP), or any combination of two or more vaccines.

Results are shown as benefit per pig, per pig place, or per herd per year, this is shown both in financial terms as well as the improvement in FCR, growth rate, mortality and throughput.

John Richardson of Intervet Schering Plough, said: "Just as important in terms of showing the benefit of vaccination, the simulator will also show when it is cost-effective not to vaccinate – simply because the return does not justify the cost of vaccination, and cost conscious pig producers need to know this."

As an example of a 600-sow breeder-finisher herd diagnosed with PRRS and M-hyo at the 'considerable' level (score 2) and APP classed as 'moderate' (1), the results based on the unit's current performance and cost structure were as show in the table.

Example calculation
Net Margin (£) No Vacc. PRRS + M-hyo + APP PRRS + M-hyo PRRS + APP PRRS M-hyo + APP M-hyo APP
Per pig 0 2.86 2.82 2.55 2.10 2.05 1.54 0.75
Per pig place per year 0 6.16 5.94 5.37 4.25 4.22 3.04 1.46
Per farm per year 0 33,869 32,675 29,541 23,350 23,200 16,721 8,023

In terms of physical performance relative to the situation without any vaccination, the regime using PRRS and M-hyo vaccination as an example was predicted to give the following improvements: growth rate by 52 g, FCR by 0.22, mortality 4.2 per cent and an increase in the number of pigs sold of 1,514 per year.

A report is then generated showing results from the economic simulator, poor and good areas of production, and advice on how to improve these aspects.

This is a hugely powerful tool from which pig producers looking to overcome PRDC problems can greatly benefit. Pig producers interested in using ResPig – which is available on a restricted basis as it is free of charge – should contact their vet initially. A simplified demonstration version can also be accessed via the Intervet web site [click here].

Further Reading

- Find out more information on the diseases mentioned in this article by clicking here.

May 2009