H2020 ECOEXTENDER Project: An alternative to antibiotics in doses of boar semen

Peptides replace antibiotics in boar semen for bacteria-free artificial insemination. Since boar semen for artificial insemination must be refrigerated and stored for days, and antibiotics will soon be illegal, an EU team found an antimicrobial peptide substitute. Artificial insemination was first demonstrated in the late 18th century. This technique offers numerous advantages for animal breeders. Since semen is much more easily transported than animals, a single breeding male can father a virtually unlimited number of offspring on many remote females.

Today, approximately 90% of cattle pregnancies in Europe are initiated artificially. In more than 99% of cases, insemination is achieved with fresh, rather than frozen, semen. The semen is used as soon as possible, but may require storage for up to three days at 15–17°C. Stored at this temperature, semen can be exposed to bacterial contamination. Breeders have controlled this growth with antibiotics. However, the use of antibiotics in livestock farming is a major cause of antibiotic resistance. Therefore, their use is strongly discouraged in Europe and will be completely banned by 2022. Breeders need an alternative way to prevent bacterial growth in stored semen. Antimicrobial peptides. The EU-funded ECOEXTENDER project developed such an alternative, focusing on pigs. Researchers developed hygienic methods for the collection, storage, and use of refrigerated semen. "To achieve this goal," says Xavier Barrera, project coordinator, "we are exploring the possibility of replacing current commercial preservation methods with antibiotic-free alternatives."

An antimicrobial peptide is key to this development. A peptide is a chain of amino acids; several of these chains form a protein. Many organisms naturally produce antimicrobial peptides as a defense against bacterial, fungal, and viral attacks. Antibiotics do not kill bacteria, but simply inhibit their reproduction. Resistance develops from mutant individuals in which suppression does not work, and which can reproduce without problems. In contrast, antimicrobial peptides do kill bacteria, altering bacterial cell membranes. First study of boar semen “The use of these peptides has been extensively studied in plants,” adds Barrera, “but their use in boar semen had not been studied before the ECOEXTENDER project.”

Specifically, the team evaluated the effect of antimicrobial peptides on porcine sperm quality. The researchers also assessed bacterial load and examined whether the bacteria had developed resistance to the peptides. The efficacy of peptide treatment was also considered based on season and other environmental factors such as concentration. Project staff also evaluated whether the peptides affected sperm potency. The research resulted in a working protocol detailing the effective use of the peptides. The team is currently seeking to artificially synthesize peptides with the same properties as those studied in this research. These should be cheaper and more suitable for large-scale application than peptides obtained from natural sources. Project researchers are seeking technical partners to assist with the synthesis.

The boar semen is diluted with a medium containing the peptides. According to the project's market research, the current Spanish market for the extender exceeds €2 million annually, while the European market exceeds €12 million. A new extender, when ready for commercialization, should capture most of this market. The ECOEXTENDER team is currently seeking to attract new clients worldwide.