Phasing out antibiotics in semen extenders with natural antimicrobials from agrifood byproducts

This line aims at replacing antibiotics in semen extenders by using naturally-derived antimicrobials. Reducing the use of antibiotics is a priority in the ecological transition, reflected in strategies such as Farm2Fork and OneHealth, mainly due to the development of antimicrobial resistance (AMR). Artificial insemination (AI) is used extensively in the swine industry (refrigerated semen) and dairy cattle (frozen). The EU applies >12 mill. L/year of seminal extenders (>2 ML/year in Spain). Antibiotics are used to avoid health problems (90/429/EEC) and the loss of reproductive efficiency of the semen. Still, it exposes millions of females to broad-spectrum antibiotics and their release into the environment (dose reflux), contributing to AMR. Alternatives have been proposed, up to now, unsatisfactory for the productive sector.

We propose replacing antibiotics with natural antimicrobial extracts (IMAPOR, Univervity of León), produced with sustainable and environmentally friendly technology developed by LIDSA (University of Santiago de Compostela) from plant residues (grape bagasse and others). This use adds value to RAISE by including the concept of circular bioeconomy. The extracts are characterized, safe for the environment, and have antimicrobial efficacy.

The starting hypothesis is that these natural extracts can effectively and safely replace antibiotics in semen extenders for pigs and bulls. A secondary hypothesis is that the antioxidant properties of the extracts would be beneficial for sperm conservation.
The general objectives for testing this hypothesis are:

  1. Obtain effective diluent-extract formulations against microorganisms of interest in porcine and bovine AI.
  2. Check that the formulations have no toxic effects on pig and bull spermatozoa and, where appropriate, whether there are any beneficial effects.
  3. Verify the effectiveness of the formulations in refrigerated (pig) and cryopreserved (bovine) semen conservation, considering the semen quality and in vitro fertility.

This project addresses a very relevant problem not only for the livestock industry but for the bioeconomy and society in general, allowing progress in reducing the use of antibiotics. The project’s main deliverables will be one or several natural extracts with antimicrobial activity and effective and antibiotic-free seminal diluents. In both cases, with potential for transfer to industry. To this end, the EBT of the ULe Bianor Biotech collaborates with the company specialized in assisted reproduction technologies Magapor and with companies involved in the pig and bovine sector. In addition, the project will value the extracts, with the potential to develop other applications in reproductive biology and bio-health.

This research will benefit the livestock sector, the associated industry, and society in general due to its impact on the circular economy and veterinary and human health (OneHealth concept). In addition to LIDSA, IMAPOR has collaborators that allow it to execute its objectives and increase its scientific and applied impact: i-Grape (production of extracts), BACRESPI (U. de León, microbiological analysis), SERIDA (in vitro fertilization) and the Univ. of Bologna (metabolic studies).