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reduced value at slaughter (20 percent), loss due to idle production facilities (3 percent), and unrealized future income based on age at culling and prior production (43 percent). Groenendaal and Galligan (1999) used simulation models to predict average losses of $35 per cow per year, increasing to $52 and $71 per cow per year after 10 and 20 years, respectively. Finally, Ott and colleagues (1999) calculated average annual losses of $22–$27 per cow. The variations in these estimates are partly the result of differences in prevalence, herd size, management practices, and the varying assumptions that underlie the calculations. In all estimates of the economic impact of JD, however, the losses are significant.
JD is spread most effectively through the movement of infected animals that contaminate a new environment, thus setting the stage for widespread exposure of more animals. Map also can be isolated from semen and embryos from affected breeding stock, although the effectiveness of this route of transmission is unknown. Consequently, JD has serious implications for domestic and international trade of live animals and germplasm. The identification of Map in animal products also can affect trade, especially if a link between Map and Crohn’s disease is demonstrated conclusively.
There are currently no federal limitations on intrastate movement of animals between premises. Participants in voluntary JD status programs can agree to the limitations on introduction of new animals as a requirement for maintaining existing status in state programs. Current control programs allow only animals from herds of equal or higher JD status to enter participating herds without conditions.
Interstate movement requires that animals be accompanied by a certificate of veterinary inspection stating that they show no clinical signs of any disease (U.S. Department of Agriculture [USDA], 2001b), including JD. Rule changes promulgated by USDA’s Animal and Plant Health Inspection Service-Veterinary Services (USDA/APHIS/VS) in 2000 also prohibit interstate movement of animals with a positive result to an official JD test, except movement directly to slaughter. Official JD tests detect the Map organism and must be completed by a laboratory approved by USDA/APHIS/VS/National Veterinary Services Laboratories. However, the rule changes refer only to animals with known test results and do not require JD testing of domesticated animals before interstate movement. Some states broadly prohibit entry of animals known to be affected by or exposed to any infectious or contagious communicable disease. Kentucky specifically defines communicable disease to include JD (Kentucky, 2002). However, no state currently requires Map testing or any specific certification as to the Map exposure status of the animal or its herd or flock of origin.