Johne’s disease (JD), caused by the Mycobacterium paratuberculosis (MAP) bacteria, imposes significant burdens on both livestock and producers. Traditionally, when considering JD, most people envision mature animals, typically three to five years old, exhibiting ongoing, severe diarrhoea along with substantial weight loss. However, in many infected herds, these overt clinical signs are less common. This is often because affected animals are culled due to diminished performance, infertility, or other health issues before the classic symptoms become apparent. As a result, an infected herd may not display obvious JD symptoms like diarrhoea but still suffer from production failures that lead to premature culling.
Johne’s Disease – What is the Impact at a Herd Level and Nationally?
By: Liam Doyle
Johne's Disease Programme Manager
An international scientific study, which included data from Ireland alongside other countries (Rasmussen et al., 2021), estimated that approximately 1% of gross milk revenue is lost annually in MAP-infected dairy herds.
(Rasmussen et al., 2021)
The Impact of Johne’s disease (JD)
This situation highlights that JD’s impact on herd economics and animal welfare can be much more subtle than what clinical signs alone reveal. A review of scientific literature on JD underscores its wide-ranging negative effects on farm operations, including:
- Decreased milk yield
- Premature culling, increasing replacement costs
- Lower market value of culled animals
- Elevated lameness levels
- Reduced feed conversion efficiency, leading to higher feed costs
- Compromised herd fertility
- Increased somatic cell counts in milk
- Elevated veterinary expenses and antimicrobial use
Importantly, these losses tend to escalate as the level of infection within a herd increases over time, resulting in greater economic and welfare consequences for affected farms. Conversely, studies show that herds with low JD prevalence experience negligible financial losses, underscoring the importance of monitoring herd JD status and implementing control measures.
One specific area where JD causes economic loss is in milk production. An international scientific study, which included data from Ireland alongside other countries (Rasmussen et al., 2021), estimated that approximately 1% of gross milk revenue is lost annually in MAP-infected dairy herds. For individual cows, this loss translates to about €31 (around US$33) per year. These losses are primarily driven by reduced milk yield and tend to be higher in regions with above-average milk prices and production levels.
The study also compared economic losses across various countries using different assumptions, resulting in an estimated annual cost to the Irish dairy industry ranging from €11.24 million (approximately US$12.09 million) to €23.85 million (about US$25.65 million). A key factor influencing these losses in all scenarios was the prevalence of JD within herds. Specifically, higher infection rates within herds significantly amplify the economic impact.
This evidence strongly supports the implementation of national JD control programs. Lowering the infection prevalence within herds can lead to substantial economic benefits across the industry, alongside improvements in animal welfare. Ultimately, proactive management and control of JD are crucial for safeguarding both the profitability and health of dairy herds.
The Irish Johne’s Control Programme (IJCP)
Remember if you need any more information about the Irish Johne’s Control Programme (IJCP) please refer to the Animal Health Ireland website for further details.
AHI Stakeholders
AHI gratefully acknowledges the financial and other contributions of our stakeholders.
