Potential Cost at Slaughter of Vaccination Lesions

Dr Jeff Eppleston, Central Tablelands RLPB - Meat and Livestock Australia

Type: Research Paper
Knowledge level: Advanced

Farm Table says:

New Zealand suggests that the greatest discounts are applied to trimmed high value lamb carcases that are destined for export in whole carcase form as a result of downgrading to a lower quality grade.

 

Caused by Gudair vaccine to the Australian sheep industry

What is the Problem?

Gudair vaccine was registered for use in Australia for the control of OJD in April 2002 and its use is expanding within the Australian sheep flock.

This study aims to document the magnitude and extent of discounts due to vaccination site lesions in New Zealand and to use this information to predict whether similar discounts could be applied either now or in the future in the Australian sheep meats market.

What did the research involve?

The development of lesions at the injection site following vaccination against JD has been recognized in sheep and cattle for many years.

Two types of lesion can develop following vaccination with JD vaccine:

  • in the tissue surrounding the site of vaccination itself
  • in the lymph nodes draining the injection site, particularly in the pre-scapular region

The total cost to a sheep industry of vaccination site lesions at slaughter can in simple terms be considered as the product of 3 factors:

  • the magnitude of the discount applied to affected carcasses
  • the proportion of carcasses entering the market that are vaccinated
  • the prevalence and severity of lesions on vaccinated carcasses

What were the key findings?

3.5.1 Historical aspects
Neoparasec a JD vaccine manufactured in France using the live Weybridge strain of Map was first licensed for use in New Zealand in 1987.

3.5.2 The magnitude of discounts reported in New Zealand
There are frequent anecdotal reports from New Zealand suggesting that the discounts applied to some vaccinated sheep can be significant.

3.5.3 The proportion of carcasses discounted
In general, downgrades are only applied to animals destined for export in the form of whole carcasses.

3.6 Factors likely to affect the impact of vaccination site lesions at slaughter in Australia

Given the lack of objective information on the real cost of vaccination lesions to the New Zealand industry, it is difficult to predict the potential impact in Australia as vaccination use increases.

3.6.1 Factors affecting the magnitude of the discount applied
Based on New Zealand experience significant discounts are applied only when carcasses that are destined for export whole are downgraded to a lower grade.

3.6.2 Factors affecting the number of vaccinates entering the market
The number of lambs vaccinated in Australia will depend on many factors, particularly the future direction taken by the industry in managing the disease.

3.6.3 Factors affecting the prevalence and severity of the lesions in vaccinates

Several factors may influence the prevalence and size of lesions in vaccinated carcasses, which in turn will affect the proportion of vaccinated carcasses requiring trimming and potentially attracting a discount.

3.6.4 Live sheep trade

The export of live sheep is a small but valuable market for Australian slaughter sheep with 6 million sheep valued at $400 million being sent live to the Middle East in 2002.

Final Comment

However, this study was conducted at a time of low sheep supply in carcasses vaccinated at the recommended site and caution should be exercised in extrapolating these results to oversupplied market situations or in sheep vaccinated at alternate sites.”

2004 - Dr Jeff Eppleston, Central Tablelands RLPB - Meat and Livestock Australia
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