Introduction

Every phase of swine production has felt the impact of disease at various levels and for various lengths of time. The system as a whole must be focused on preventing the introduction of new disease and be prepared to minimize the effects of any that penetrate the system. Preventing the introduction of new disease begins at the source of all replacements, both boars and gilts, and their isolation and acclimation prior to entry into the system. Vaccination and monitoring procedures (blood testing), traffic control (both human and animal), animal flow procedures such as all in, all out by site (or at least by barn), and biosecurity are also points of control in the prevention of disease entry into the system. Ultimately, when we do experience an outbreak, we rely on treatment to save us when the system is compromised, as today's production systems are considered to be too large for depopulation - repopulation to be an economically feasible alternative to eliminate disease.

The ideal situation is that our protocol will prevent the entry of diseases, but the reality is that, despite the most stringent procedures for biosecurity, blood testing and vaccination, a disease may still get through and must be dealt with. Unfortunately, many managers and/or owners feel they cannot justify the cost of prevention until it is too late and viewed as hindsight. The risk of entry of any new disease to a production system is reduced dramatically by limiting the number of animals allowed into the system from outside sources. Since the greatest number of new entries are replacement females, the logical choice is to raise all replacement females within the system. This has a number of drawbacks, however, and can be a difficult procedure to manage. A second choice is to utilize artificial insemination (AI) throughout the entire system, eliminating the entry of boars into the system. Since boars are generally sourced from different production farms than gilts, it makes sense to utilize AI, both from a health standpoint as well as a genetic improvement standpoint.

Although there are diseases that can be spread through semen, many can be eliminated as a threat through proper testing and vaccination protocols. For example, the PRRSV complex can be eliminated as a threat by only allowing PRRSV negative animals to enter the system. In the case of the boar stud manager, however, he or she may not have control over the health status of the source and have to deal with boars with positive PRRSV titers. If this is the case, the threat can be reduced by proper monitoring of both blood and semen along with vaccination procedures. It has also been suggested that the PRRSV virus is unstable in extended semen and storage for three to 24 hours renders it incapable of producing infection. Other microorganisms that can cause reproductive failure or be spread through semen include Porcine Parvovirus, Leptospira and Pseudorabies virus. A number of other organisms can be transmitted through semen but are not considered a potential threat due to their absence from the United States swine population (African Swine Fever, Hog Cholera).

With the implementation of AI there is a potential point of production loss throughout the system due to reproductive failure in the sow herd caused by reduced sperm output in the boar stud due to disease. If, for example, 5,000 doses of semen are required each week to maintain the minimum number of matings within a given system for that week, the boar stud should be sized to produce 6,000 doses as a buffer (20% overage). This buffer allows for compensation during minor glitches such as hot weather or minor disease flare-ups and prevents breaks in production. If, however, the stud is completely closed, a contingency plan must be in place to insure that the 5,000 matings per week can still be performed until the stud is back on line. The breeding and farrowing personnel who rely on high quality semen to maintain production levels that will insure a bonus may not be concerned with the quality of the genetics of this replacement semen, although the managers of the nurseries and finishers who depend on the performance of the pigs for their bonus will be. Therefore, it is in the best interest of the owners, managers and all employees throughout the system to have access to the best quality genetics from a disease free source.

Alternate semen sources should be identified as soon as the decision is made to build a stud. The criteria for the alternate source of semen should be the same in terms of health status, isolation, blood testing, vaccination, etc. as that followed by the main stud. Once a source has been identified and a supply agreement has been worked out, a "fire drill" should be conducted to insure that the stud supplying the replacement semen can do its part and the shipping or delivery mechanism chosen is compatible with the breeding farm's schedule.

Maximizing reproductive efficiency and keeping nursery and finisher pens full is the overall goal of the entire swine production system. The utilization of AI to achieve optimum pig performance through the selection and use of superior genetics should be the driving decision to incorporate this technology. The benefits of disease control and potential for increased reproductive performance are additional advantages that alone justify AI's implementation. By reducing the entry of outside animals and controlling the entry of diseases via serum and semen testing and vaccination, AI can be instrumental in preventing reproductive failure in the sow herd.