In 2024, the board of directors of the Minnesota Pork Board adopted five foundational strategic pillars, one of which is the enhancement of animal well-being. Intrinsic to animal well-being are animal health, disease prevention and ultimately, disease elimination from pig populations.
With the leadership and directive of Minnesota Pork, a working group was tasked with providing direction and guidance with the goal of arriving at an action plan consistent with the goals under the foundational pillar of animal well-being. The recommendation from this group was for Minnesota pork producers to lead the nation in the elimination of the endemic disease, and to pursue the goal of the elimination of Mycoplasma hyopneumiae at the state level. From this beginning, the Minnesota Animal Health Task Force was created and has provided the leadership and direction, including the submission of a resolution to the US Swine Health Improvement Plan with subsequent approval by the House of Delegates, for the creation of a working group to explore the potential for certifying Mhp within the program.
Why Mhp?
Mhp, which causes what is referred to as enzootic pneumonia, has also been identified as one of the pathogens involved in Swine Respiratory Disease Complex. Persistent cough, growth retardation and increased susceptibility to other respiratory infections are signs of enzootic pneumonia, resulting in the need for increased antibiotic use in the grow-finish phase. Estimates of the burden of disease range from a few, to over $10 per market pig depending on factors including co-infections with porcine reproductive and respiratory syndrome virus and influenza.
Mhp elimination programs were initiated in several European countries in the late 1980s, with successful outcomes at both the regional and national level. In the U.S., beginning in the early 2000s, protocol and programs were developed to eliminate Mhp at the herd and production system level. These protocols have been improved upon, with the research into exposure methods, duration of shedding of positive pigs to susceptible populations and closure time requirements providing guidance to veterinarians and producers. The observation that the goal of achieving Mhp-negative status at the breeding herd and production system levels with herd closure is attainable has been a catalyst for producers and veterinarians to work toward Mhp elimination.
One important aspect to highlight is that a producer can pursue Mhp-negative status and be confident that this status can most probably be maintained regardless of the Mhp status of neighboring pigs. The observations and empirical evidence over the past 10-15 years suggest that the reinfection rate of breeding herds with Mhp is low, approaching 2 to 3% incidence in breeding herds. Additionally, the rate of lateral transmission of Mhp among growing pig populations, based on observation of clinical signs consistent with Mhp also suggests a very low incidence of spatially-associated transmission of Mhp in growing pig populations. In contrast, the Morrison Swine Health Monitoring Project data indicate a 20 to 35% annual incidence of PRRSV in breeding herds in that database. Several studies investigating the incidence of PRRSV in growing pig populations suggest a 50 to 90% incidence in this phase of production.
What is the current Mhp status of Minnesota producers?
Based on initial an initial survey of Minnesota-based MSHMP participants, 96 of 107 sow farms, representing 62% of the Minnesota breeding herd inventory, report a current negative Mhp status. Of the eleven reporting a positive status. three of these farms are under closure to eliminate Mhp.
Why pursue Mhp-negative status?
The job of the producers, the consulting veterinarians and those working in research is to constantly work toward improved animal well-being and sustainability on our farms. The research has been conducted and the evidence produced, documenting the burden of disease from Mhp. Additionally, researchers, veterinarians and producers have demonstrated that Mhp-negative status can be achieved and maintained, and the higher likelihood of successful elimination of Mhp from the breeding herds and growing pig populations. Working toward elimination of Mhp, first at a state level and ultimately at the national level is the right thing to do in the interest of animal well-being and sustainability.
The MAHTF, with members including consulting veterinarians, subject matter experts and the Swine Disease Eradication Center of the University of Minnesota will be offering guidance and leadership to both the state initiative as well as the US SHIP working group. We look forward to witnessing the long-term benefits of this initiative to the Minnesota and U.S. swine industry.
This article was written by Mark Schwartz of the University of Minnesota for the National Hog Farmer.