The bioactivity and bioavailability of antibiotics are common parameters assessed for an antibiotic intended for systemic treatment of bacterial infections. This means that the blood or tissue concentrations of antibiotic, given at various doses, are determined at different times after treatment. Similar studies are needed to determine if the antibiotics maintain their bioactivity in semen extender for 1-5 days. Furthermore, the shelf-life or expiry date is clearly printed on the labels of injectable antibiotics. Few, if any, packages of semen extender display the expiry date of its antibiotics.
Bacteria are very adaptable and readily change to develop resistance to antibiotics.
This changing resistance of bacteria to antibiotics likely occurs in boar semen. An obvious recommendation would be to assess the antibiotics for your own AI program and procedures. This includes determining the antibiotic sensitivity of the common contaminants and evaluating the effects of the antibiotics on semen quality, motility and subsequent farrowing rates. Certain viruses, such as PRRS virus, have been isolated from boar semen and these viral infections alter the quality of semen for variable periods of time. The roles of the viruses on conception and fertilization and the potential interaction of the virus with bacterial contaminants remain to be elucidated.