Peptides replace antibiotics in boar semen for bacteria-free artificial insemination With swine semen for artificial insemination having to be refrigerated and stored for days, and antibiotics soon illegal, an EU team found an antimicrobial-peptide substitute. Food and Natural Resources © ECOEXTENDER Artificial insemination was first demonstrated in the late 18th century. The technique offers numerous advantages for animal breeders. Since semen can be much more easily transported than animals, a single breeding male can sire a virtually unlimited number of offspring in many remote females. Today, approximately 90 % of livestock pregnancies in Europe are initiated artificially. In more than 99 % of cases, insemination is achieved using fresh semen, rather than frozen. The semen is used as quickly as possible but may still require storage for up to 3 days at 15–17 °C. Stored at this temperature, the semen may be subject to bacterial contamination. Breeders have been controlling such growth with antibiotics. However, the use of antibiotics in animal husbandry is a major cause of antibiotic resistance. Therefore, use is strongly discouraged in Europe, and it will be completely banned by 2022. Breeders need an alternative way of preventing bacterial growth in stored semen. Antimicrobial peptides The EU-funded ECOEXTENDER project developed such an alternative, focused on swine. Researchers developed hygienic methods for the collection, storage and use of refrigerated semen. “To achieve this goal,” says Xavier Barrera, project coordinator, “we explored the replacement of current commercial preservation media with alternatives that do not contain antibiotics.” Key to the development is an antimicrobial peptide. A peptide is a string of amino acids; several such strings make up a protein. Many types of organism naturally produce antimicrobial peptides, as defence against bacterial, fungal and viral attack. Antibiotics do not kill bacteria, they merely suppress reproduction. Resistance evolves from mutant individuals for which the suppression does not work, which are then able to reproduce unhindered. In contrast, antimicrobial peptides do kill bacteria. They do so by disrupting the bacterial cell membranes. First swine semen study “The use of these peptides has been well studied in plants,” adds Barrera, “but their use in boar semen had been unstudied prior to the ECOEXTENDER project.” Specifically, the team evaluated the effect of antimicrobial peptides on swine sperm quality. Researchers also assessed the bacterial load, and examined whether bacteria had developed resistance to the peptides. Further considerations were the effectiveness of the peptide treatment according to season, and other environmental factors such as concentration. Project personnel also assessed whether the peptides affected the sperm’s potency. The research yielded a working protocol, which details effective use of the peptides. The team is currently looking to artificially synthesise peptides having the same properties as those studied in this research. These should prove more economical, and more suited to large-scale application, than peptides obtained from natural sources. Project researchers are looking for technical partners to help with the synthesis. Swine semen is diluted with a medium that will eventually contain the peptides. According to the project’s marketing study, the current Spanish market for the diluent is over EUR 2 million per year, whereas the European market is over EUR 12 million. A new diluent, when it is ready for commercial release, should be able to take over most of this market. The ECOEXTENDER team is attempting to attract new customers worldwide. Keywords ECOEXTENDER, semen, antibiotic, swine, antimicrobial peptide, boar semen, artificial insemination, diluent
