All new breeding animals should come from a single source, using a genetic-pyramid production system, say Johnna Seaman and Thomas Fangman, DVM, University of Missouri.
In a pyramid system, the purebred animals at the top (nucleus herd) are the highest level of biosecurity and health status. Commercial production animals are at the bottom of the pyramid, with multiplier animals in between. Replacement animals for your herd should come from as high a level in the pyramid as possible.
When using artificial insemination and purchasing semen from an outside source, there’s still a risk of transmitting disease through the semen, especially reproductive viruses. While this risk is not as high as bringing in actual animals, it’s important to purchase semen from a boar stud that has a strict biosecurity program in place. The biosecurity for a boar stud is much the same as that of a production unit, including isolation and acclimatization of new boars.
Isolation facilities should be located at least 500 yards from the main herd. A minimum of 30 days isolation and 30 days acclimatization are necessary for biosecurity, although there may be reasons for longer periods. During isolation, the new animals should be blood tested and observed for signs of disease.
If animals crossing state lines, animals must be tested for pseudorabies and brucellosis. Additional disease tests often include Mycoplasma hyopneumonia, porcine respiratory and reproductive syndrome, TGE, swine influenza, Leptospirosis and Actinobacillus pleuropneumoniae. Be sure to evaluate test results with your veterinarian before moving any animals from isolation.
Acclimatization may be done in the same facility as isolation, but it should involve only one group of animals at a time. During this period, new animals should be exposed to the pathogens that are present in the main herd. You can do this by placing manure from the main herd into the facility or brining in cull animals or failure-to-thrive nursery pigs.
You need to know the main herd’s current disease profile. You or your veterinarian should check with the supplier to ensure that the herd has not broken with any diseases since you received animals. The specific vaccination schedule for replacement animals should be arranged with your herd veterinarian.